Transphorm (TGAN) S-1 20 Jan 21 IPO registration Financial data

Cover

Cover	Jun. 01, 2020
Cover [Abstract]
Document Type	S-1
Entity Registrant Name	Transphorm, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1858829
Entity Address, Address Line One	75 Castilian Drive
Entity Address, City or Town	Goleta
Entity Address, Postal Zip Code	93117
City Area Code	805
Local Phone Number	456-1300
Entity Central Index Key	0001715768
Amendment Flag	false
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Address, State or Province	CA
Entity Ex Transition Period	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents		$ 4,369	$ 2,875	$ 3,069
Accounts receivable, net, including related parties		1,125	709	280
Inventory		1,372	990	852
Prepaid expenses and other current assets		1,743	783	624
Total current assets		8,609	5,357	4,825
Property and equipment, net		1,432	1,770	2,132
Goodwill		1,362	1,325	1,306
Intangible assets, net		1,062	1,313	1,958
Other assets		401	497	278
Total assets		12,866	10,262	10,499
Current liabilities:
Accounts payable and accrued expenses		2,687	2,383	1,351
Deferred revenue		178	0
Development loan		10,000	5,000	0
Revolving credit facility, including accrued interest		10,153	10,458	10,346
Deferred revenue			0	3,000
Unfunded commitment to joint venture		1,684	1,688	659
Accrued payroll and benefits		1,325	1,159	1,172
Total current liabilities		26,027	20,688	16,528
Development loans, net of current portion		0	10,000	0
Promissory note		16,327	16,169	15,852
Total liabilities		42,354	46,857	32,380
Commitments and Contingencies
Convertible preferred stock, shares outstanding (in shares)			31,850,304
Convertible preferred stock, shares issued (in shares)			31,850,304	31,850,304
Convertible preferred stock, authorized (in shares)			31,850,304
Total convertible preferred stock		0	$ 85,658	$ 85,658
Stockholders’ deficit:
Common stock			4	4
Additional paid-in capital			22,400	21,829
Additional Paid In Capital, After Merger Adjustments		128,385	22,404
Accumulated deficit		(157,112)	(143,915)	(128,632)
Accumulated other comprehensive loss		(765)	(742)	(740)
Total stockholders’ deficit		(29,488)	(122,253)	(107,539)
Total liabilities, convertible preferred stock and stockholders’ deficit		$ 12,866	$ 10,262	$ 10,499
Series 1 Preferred Stock
Current liabilities:
Convertible preferred stock, shares outstanding (in shares)		0	12,433,953	12,433,953
Convertible preferred stock, shares issued (in shares)		0	12,433,953	12,433,953
Convertible preferred stock, authorized (in shares)		0	12,438,704	12,438,704
Total convertible preferred stock		$ 0	$ 39,658	$ 39,658
Series 2 Preferred Stock
Current liabilities:
Convertible preferred stock, shares outstanding (in shares)		0	7,499,996	7,499,996
Convertible preferred stock, shares issued (in shares)		0	7,499,996	7,499,996
Convertible preferred stock, authorized (in shares)		0	7,507,699	7,507,699
Total convertible preferred stock		$ 0	$ 30,000	$ 30,000
Series 3 Preferred Stock
Current liabilities:
Convertible preferred stock, shares outstanding (in shares)		0	4,000,000	4,000,000
Convertible preferred stock, shares issued (in shares)		0	4,000,000	4,000,000
Convertible preferred stock, authorized (in shares)		0	4,000,000	4,000,000
Total convertible preferred stock		$ 0	$ 16,000	$ 16,000
Stockholders’ deficit:
Common stock	$ 4		$ 0

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Convertible preferred stock, authorized (in shares)	31,850,304
Convertible preferred stock, shares issued (in shares)	31,850,304	31,850,304
Convertible preferred stock, shares outstanding (in shares)	31,850,304
Common stock, shares authorized (in shares)	29,012,034	29,012,034
Common stock, shares issued (in shares)	4,220,998	4,219,606
Common stock outstanding (in shares)	4,220,998	4,219,606
Common stock, par value (in usd per share)	$ 0.0001	$ 0.001
Series 1 Preferred Stock
Convertible preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Convertible preferred stock, authorized (in shares)	12,438,704	12,438,704
Convertible preferred stock, shares issued (in shares)	12,433,953	12,433,953
Convertible preferred stock, shares outstanding (in shares)	12,433,953	12,433,953
Series 2 Preferred Stock
Convertible preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Convertible preferred stock, authorized (in shares)	7,507,699	7,507,699
Convertible preferred stock, shares issued (in shares)	7,499,996	7,499,996
Convertible preferred stock, shares outstanding (in shares)	7,499,996	7,499,996
Series 3 Preferred Stock
Convertible preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Convertible preferred stock, authorized (in shares)	4,000,000	4,000,000
Convertible preferred stock, shares issued (in shares)	4,000,000	4,000,000
Convertible preferred stock, shares outstanding (in shares)	4,000,000	4,000,000
Common Stock
Convertible preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Convertible preferred stock, authorized (in shares)	29,012,034	29,012,034
Convertible preferred stock, shares issued (in shares)	4,220,998	4,219,606
Convertible preferred stock, shares outstanding (in shares)	4,220,998	4,219,606

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue, net	$ 1,929	$ 994	$ 9,358	$ 2,011	$ 11,934	$ 1,358
Operating expenses:
Cost of goods sold	2,043	1,625	4,746	4,211	6,492	4,601
Research and development	1,071	2,041	4,131	6,245	8,146	9,351
Sales and marketing	547	572	1,593	2,098	2,609	3,626
General and administrative	2,688	1,270	7,838	4,015	6,606	5,675
Total operating expenses	6,349	5,508	18,308	16,569	23,853	23,253
Loss from operations	(4,420)	(4,514)	(8,950)	(14,558)	(11,919)	(21,895)
Interest expense	191	191	569	567	758	710
Loss in joint venture	1,943	777	5,218	3,004	3,703	2,404
Changes in fair value of promissory notes	709	17	46	101	167	1,060
Other income, net	(523)	(53)	(1,586)	(513)	(1,264)	(271)
Loss before tax expense	(6,740)	(5,446)	(13,197)	(17,717)	(15,283)	(25,798)
Tax expense	0	0	0	0	0	0
Net loss	$ (6,740)	$ (5,446)	$ (13,197)	$ (17,717)	$ (15,283)	$ (25,798)
Net loss per share - basic and diluted	$ (0.19)	$ (0.19)	$ (0.39)	$ (0.63)	$ (3.62)	$ (6.11)
Weighted average common shares outstanding - basic and diluted	35,156,918	28,153,555	34,072,176	28,153,555	4,219,656	4,219,606

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,740)	$ (5,446)	$ (13,197)	$ (17,717)	$ (15,283)	$ (25,798)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	6	5	(23)	7	(2)	2
Other comprehensive (loss) income, net of tax	6	5	(23)	7	(2)	2
Comprehensive loss	$ (6,734)	$ (5,441)	$ (13,220)	$ (17,710)	$ (15,285)	$ (25,796)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Deficit - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Income
Beginning balance (in shares) at Dec. 31, 2017		4,219,606
Beginning balance at Dec. 31, 2017	$ (82,328)	$ 4	$ 21,244	$ (102,834)	$ (742)
Stock-based compensation	585		585
Other comprehensive income	2				2
Net loss	(25,798)			(25,798)
Ending Balance at Dec. 31, 2018	$ (107,539)	$ 0	21,833	(128,632)	(740)
Ending balance (in shares) at Dec. 31, 2018	4,219,606	4,219,606
Ending balance at Dec. 31, 2018	$ (107,539)	$ 4	21,829	(128,632)	(740)
Stock-based compensation	435		435
Other comprehensive income	7				7
Net loss	(17,717)			(17,717)
Ending Balance at Sep. 30, 2019	$ (124,814)	$ 0	22,268	(146,349)	(733)
Ending balance (in shares) at Sep. 30, 2019		4,219,606
Beginning balance (in shares) at Dec. 31, 2018	4,219,606	4,219,606
Beginning balance at Dec. 31, 2018	$ (107,539)	$ 4	21,829	(128,632)	(740)
Beginning Balance at Dec. 31, 2018	$ (107,539)	$ 0	21,833	(128,632)	(740)
Stock options exercised (in shares)	1,392	1,392
Stock options exercised	$ 5		5
Stock-based compensation	566		566
Other comprehensive income	(2)				(2)
Net loss	(15,283)			(15,283)
Ending Balance at Dec. 31, 2019	$ (122,253)	$ 0	22,404	(143,915)	(742)
Ending balance (in shares) at Dec. 31, 2019	4,220,998	4,220,998
Ending balance at Dec. 31, 2019	$ (122,253)	$ 4	22,400	(143,915)	(742)
Beginning balance (in shares) at Jun. 30, 2019		4,219,606
Beginning Balance at Jun. 30, 2019	(119,532)	$ 0	22,109	(140,903)	(738)
Stock-based compensation	159		159
Other comprehensive income	5				5
Net loss	(5,446)			(5,446)
Ending Balance at Sep. 30, 2019	$ (124,814)	$ 0	22,268	(146,349)	(733)
Ending balance (in shares) at Sep. 30, 2019		4,219,606
Beginning balance (in shares) at Dec. 31, 2019	4,220,998	4,220,998
Beginning Balance at Dec. 31, 2019	$ (122,253)	$ 0	22,404	(143,915)	(742)
Stock options exercised (in shares)	6,821	6,821
Stock options exercised	$ 27		27
Stock-based compensation	820		820
Conversion of shares in connection with the Reverse Merger (in shares)		23,933,949
Stock Issued During Period, Value, Conversion of Convertible Securities	85,658	$ 3	85,655
Shares redeemed (in shares)		(52,773)
Stock Repurchased During Period, Value	(211)		(211)
Shares issued in connection with the Reverse Merger (in shares)		1,650,000
Stock Issued During Period, Value, New Issues Related To Merger	(50)		(50)
Issuance of common stock, net (in shares)		5,380,000
Stock Issued During Period, Value, New Issues	19,741	$ 1	19,740
Other comprehensive income	(23)				(23)
Net loss	(13,197)			(13,197)
Ending Balance at Sep. 30, 2020	$ (29,488)	$ 4	128,385	(157,112)	(765)
Ending balance (in shares) at Sep. 30, 2020	35,266,496	35,266,496
Ending balance at Sep. 30, 2020	$ (29,488)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	127,501
Beginning balance (in shares) at Feb. 11, 2020	50,325,662
Shares redeemed (in shares)	(52,773)
Shares issued in connection with the Reverse Merger (in shares)	1,650,000
Ending balance (in shares) at Feb. 12, 2020	4,171,571
Beginning balance (in shares) at Jun. 30, 2020		35,135,520
Beginning Balance at Jun. 30, 2020	$ (23,352)	$ 4	127,787	(150,372)	(771)
Stock options exercised (in shares)	3,475	3,475
Stock options exercised	$ 14		14
Stock-based compensation	584		584
Other comprehensive income	6				6
Net loss	(6,740)			(6,740)
Ending Balance at Sep. 30, 2020	$ (29,488)	$ 4	$ 128,385	$ (157,112)	$ (765)
Ending balance (in shares) at Sep. 30, 2020	35,266,496	35,266,496
Ending balance at Sep. 30, 2020	$ (29,488)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	127,501

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Statement) ¥ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net loss	$ (13,197,000)	$ (17,717,000)	$ (15,283,000)	$ (25,798,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Capitalized interest cost	(193,000)	455,000	608,000	496,000
Depreciation and amortization	632,000	920,000	1,216,000	1,374,000
Inventory write-off	274,000	0	155,000	0
Stock-based compensation	820,000	435,000	566,000	585,000
Loss on disposal of property and equipment			0	75,000
Loss in joint venture	5,218,000	3,004,000	3,703,000	2,404,000
Changes in fair value of promissory notes	46,000	101,000	167,000	1,060,000
Changes in operating assets and liabilities:
Accounts receivable	(562,000)	(45,000)	(429,000)	(280,000)
Inventory	(656,000)	(288,000)	(293,000)	(669,000)
Prepaid expenses and other current assets	(965,000)	(236,000)	(154,000)	396,000
Other assets	96,000	(51,000)	(42,000)	16,000
Accounts payable and accrued expenses	304,000	(766,000)	509,000	(323,000)
Deferred revenue	178,000	3,000,000	(3,000,000)	3,000,000
Accrued payroll and benefits	166,000	(136,000)	(13,000)	(21,000)
Net cash used in operating activities	(12,693,000)	(11,324,000)	(12,290,000)	(17,685,000)
Cash flows from investing activities:
Purchases of property and equipment	(46,000)	(155,000)	(203,000)	(332,000)
Investment in joint venture	(5,327,000)	(1,696,000)	(2,698,000)	(1,852,000)
Net cash used in investing activities	(5,373,000)	(1,851,000)	(2,901,000)	(2,184,000)
Cash flows from financing activities:
Proceeds from issuance of development loans	0	13,000,000	15,000,000	0
Proceeds from Stock Options Exercised	32,000	0
Payments for Repurchase of Common Stock	(211,000)	0
Repayments of Other Debt	(50,000)	0
Proceeds from Issuance of Common Stock	19,741,000	0
Proceeds from issuance of revolving credit facility			0	10,000,000
Principal payments on promissory notes			0	(13,000,000)
Proceeds from issuance of Series 3 convertible preferred stock			0	16,000,000
Net cash provided by financing activities	19,512,000	13,000,000	15,000,000	13,000,000
Effect of foreign exchange rate changes on cash and cash equivalents	48,000	17,000	(3,000)	(35,000)
Net decrease in cash and cash equivalents	1,494,000	(158,000)	(194,000)	(6,904,000)
Cash and cash equivalents at beginning of year	2,875,000	3,069,000	3,069,000	9,973,000
Cash and cash equivalents at end of year	4,369,000	2,911,000	2,875,000	3,069,000
Supplemental disclosures of cash flow information:
Interest expense paid	762,000	496,000	496,000	328,000
Private placement offering cost			$ 177,000	$ 0
Supplemental non-cash financing activity:
Financing Receivable, Credit Loss, Expense (Reversal)	146,000
Licensing Revenue From Related Parties	(5,000,000)
Notes Reduction	$ 5,000	$ 0

Business and Basis of Presentat

Business and Basis of Presentation	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Transphorm, Inc. (“Parent”) develops gallium nitride (“GaN”) semiconductor components used in power conversion and is headquartered in Goleta, California. Parent’s wholly owned-subsdiary, Transphorm Technology, Inc., was incorporated in the State of Delaware on February 22, 2007. Throughout these notes, “the Company,” “Transphorm,” “we,” “us” and “our” refer to Parent and its direct and indirect wholly-owned subsidiaries. Transphorm Technology and its subsidiaries hold all material assets and conduct all business activities and operations of the Company. Transphorm Technology’s activities to date have been primarily performing research and development, establishing manufacturing infrastructure, market sampling, product launch, hiring personnel, and raising capital to support and expand these activities. Transphorm Japan, Inc. was established in Japan in February 2014 to secure Transphorm’s production capacity and establish a direct presence in Asian markets. Transphorm Aizu, Inc. was established in Japan to manage the financial transactions around Aizu Fujitsu Semiconductor Wafer Solution Limited, Transphorm’s joint venture wafer fabrication facility located in Aizu Wakamatsu, Japan (“Aizu”). Transphorm Japan Epi, Inc. was established in Japan in 2019 to enable the operational capacity of the reactors held in Aizu. In management’s opinion, the accompanying unaudited condensed consolidated financial statements of Transphorm reflect all adjustments of a normal and recurring nature that are necessary for a fair presentation of the results for the interim period ended September 30, 2020, but are not necessarily indicative of the results that will be reported for the entire year or any other interim period. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with Accounting Principles Generally Accepted in the United States of America (“GAAP”) have been condensed or omitted. The aforementioned unaudited condensed consolidated financial statements are prepared in conformity with GAAP and in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission. The interim information should be read in conjunction with the audited financial statements and notes thereto included in the Company’s Amendment No. 2 to Form 8-K filed on March 31, 2020. The consolidated balance sheet as of December 31, 2019 is derived from those audited financial statements. The preparation of interim unaudited condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Material estimates subject to change include, among other items, the determination of allowance for loan and lease losses and allowance for off-balance sheet items, other-than-temporary impairment, securities valuations, the fair value of other assets and liabilities acquired in a business combination and income taxes. Actual results could differ from those estimates. Reverse Merger On February 12, 2020, our wholly-owned subsidiary, Peninsula Acquisition Sub, Inc., a corporation formed in the State of Delaware (“Acquisition Sub”), merged with and into Transphorm Technology (formerly known as Transphorm, Inc.), the corporate existence of Acquisition Sub ceased, and Transphorm Technology became our wholly-owned subsidiary (such transaction, the “Merger”). As a result of the Merger, we acquired the business of Transphorm Technology. The Merger was effective as of February 12, 2020, upon the filing of a certificate of merger with the Secretary of State of the State of Delaware. Immediately after completion of the Merger, we adopted Transphorm Technology’s former company name, “Transphorm, Inc.”, as our company name. The Merger was treated as a recapitalization and reverse acquisition for financial reporting purposes, and Transphorm Technology is considered the acquirer for accounting purposes. As a result of the Merger and the change in our business and operations, a discussion of the past financial results of our predecessor, Peninsula Acquisition Corporation, is not pertinent, and under applicable accounting principles, the historical financial results of Transphorm Technology, the accounting acquirer, prior to the Merger are considered our historical financial results. At the effective time of the Merger, (i) each share of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger was converted into the right to receive (a) 0.08289152527 shares of our common stock (in the case of shares held by accredited investors) or (b) $4.00 multiplied by 0.08289152527 (in the case of shares held by unaccredited investors), with the actual number of shares of our common stock issued to the former holders of Transphorm Technology’s common stock equal to 4,171,571, (ii) 51,680,254 shares of Transphorm Technology’s Series 1 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 12,433,953 shares of our common stock, (iii) 38,760,190 shares of Transphorm Technology’s Series 2 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 7,499,996 shares of our common stock, and (iv) 31,850,304 shares of Transphorm Technology’s Series 3 preferred stock issued and outstanding immediately prior to the closing of the Merger were converted into 4,000,000 shares of our common stock. As a result, 28,105,520 shares of our common stock were issued to the former holders of Transphorm Technology’s issued and outstanding capital stock after adjustments due to rounding for fractional shares. Immediately prior to the effective time of the Merger, an aggregate of 682,699 shares of our common stock, owned by the stockholders of Peninsula Acquisition Corporation prior to the Merger, were forfeited and cancelled. In addition, pursuant to the Merger Agreement, (i) options to purchase 29,703,285 shares of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger under Transphorm Technology’s 2007 Stock Plan (the “2007 Plan”) and 2015 Equity Incentive Plan (the “2015 Plan”) were assumed and converted into options to purchase 2,461,923 shares of our common stock, (ii) warrants to purchase 186,535 shares of Transphorm Technology’s common stock issued and outstanding immediately prior to the closing of the Merger were assumed, amended and converted into warrants to purchase 15,461 shares of our common stock, and (iii) Transphorm Technology’s outstanding convertible promissory note was amended to be convertible at the option of the holder, into shares of our common stock at a conversion price of $5.12 per share, with 3,076,171 being the maximum number of shares of our common stock issuable upon conversion of the convertible promissory note. As of September 30, 2020, there was $15.0 million of principal and $448 thousand of accrued and unpaid interest outstanding on the convertible promissory note. All per share and share amounts for the three and nine months ended September 30, 2019 have been retroactively adjusted to reflect the effect of the Merger. Going Concern The accompanying unaudited condensed consolidated condensed financial statements have been prepared assuming that the Company will continue as a going concern. As included in the accompanying unaudited condensed consolidated financial statements, the Company has generated recurring losses from operations, sustained negative cash flows from operating activities, and has an accumulated deficit and has a working capital deficiency. These factors raise substantial doubt about the Company’s ability to continue as a going concern for the next twelve months from the issuance of these financial statements. Management plans to raise additional working capital to fund operations through the issuance of stock to investors, license of intellectual property and/or issuance of notes payable. The Company raised $19.7 million from the sale of common stock in February 2020 as described in Note 9 - Stockholders’ Equity. However, there is no assurance that the Company will be successful in raising additional capital. The ability of the Company to continue as a going concern is dependent on its ability to raise significant additional capital to fund operating losses until it is able to generate liquidity from its business operations. To the extent sufficient financing is not available, the Company may not be able to, or may be delayed in, developing its offerings and meeting its obligations. The Company will continue to evaluate its projected expenditures relative to its available cash and to evaluate financing alternatives in order to satisfy its working capital and other cash requirements. The accompanying unaudited condensed consolidated financial statements do not reflect any adjustments that might result from the outcome of these uncertainties. Impact of COVID-19 on Our Business The COVID-19 pandemic has adversely disrupted and will further disrupt the operations at certain of our customers, partners, suppliers and other third-party providers for an uncertain period of time, including as a result of travel restrictions, adverse effects on budget planning processes, business deterioration, and/or business shutdowns, all of which has impacted our business and results of operations. Some of our customers have experienced delays in their internal development programs and design cycles with our GaN products due to the effects of COVID-19, which have led to postponements of their orders of our products and postponements of determinations that our products will be used in their designs for new products under development with corresponding delays in their market introduction and our revenues. The future impact of COVID-19 cannot be predicted with certainty and may make it more difficult or preclude us from raising additional capital, increase our costs of capital and otherwise adversely affect our business, results of operations, financial condition and liquidity. Significant Accounting Policies Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of the Parent and its wholly-owned subsidiaries, Transphorm Technology, Transphorm Japan, Inc., Transphorm Japan Epi, Inc. and Transphorm Aizu, Inc. Upon consolidation, all significant intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates and assumptions on historical experience, knowledge of current conditions, and its belief of what could occur in the future, given available information. Actual results could differ from those estimates, and such differences could be material to the condensed consolidated financial statements. Estimates are used for, but not limited to, the determinations of fair value of stock awards and promissory notes, accrual of liabilities, revenue recognition, inventory reserve, and useful lives for property and equipment. Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported condensed consolidated financial statements. Cash and Cash Equivalents The Company considers all highly-liquid investments with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist principally of bank deposits and money market funds. Other assets in the condensed consolidated balance sheets as of September 30, 2020 and December 31, 2019 include cash of $75 thousand. Foreign Currency Risk The Company is exposed to foreign currency risk due to its operations in Japan. Assets and liabilities of the operations are re-measured into U.S. currency at exchange rates in effect at the balance sheet dates through the condensed consolidated statements of comprehensive income. Gains or losses resulting from foreign currency transactions are re-measured using the rates on the dates on which those elements are recognized during the period and are included in other income or expense in the unaudited condensed consolidated statements of operations. As of September 30, 2020 and December 31, 2019, the Company had foreign cash and cash equivalents of $41 thousand and $55 thousand, respectively, which represented 0.9 percent and 1.9 percent, respectively, of total cash and cash equivalents. Concentrations of Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the financial institution holding its cash. The Company’s investment policy restricts investments to high-quality investments and limits the amounts invested with any one issuer, industry or geographic area. Risks associated with cash holdings in excess of insured limits are mitigated by banking with high-quality institutions. To date, the Company has not experienced any significant losses on its cash and cash equivalents. The Company periodically evaluates the relative credit standing of these financial institutions. The Company is subject to risks common in the power conversion components industry, including, but not limited to, technological obsolescence, dependence on key personnel, market acceptance of its products, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed. Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes the impact of foreign currency translation adjustments. Accounts Receivable Accounts receivable are analyzed and allowances for uncollectible accounts are recorded, as required. Provisions for uncollectible accounts, if any, are recorded as bad debt expense and included in general and administrative expenses in the accompanying unaudited condensed consolidated statements of operations. The process for determining the appropriate level of allowances for doubtful accounts involves judgment, and the Company considers such factors as the age of the underlying receivables, historical and projected collection trends, the composition of outstanding receivables, current economic conditions and regulatory changes. An account is fully reserved when reasonable collection efforts have been unsuccessful and it is probable that the receivable will not be recovered. No significant losses on accounts receivable have been recorded as of September 30, 2020 and December 31, 2019. Inventory Inventory is stated at the lower of cost (first-in, first-out method) or net realizable value. The Company periodically reviews the value of items in inventory and records write-downs or write-offs based on its assessment of slow moving or obsolete inventory. The Company maintains an inventory reserve for obsolete inventory and generally makes inventory value adjustments against the inventory reserve. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally ranging from three The Company evaluates the carrying amount of its property and equipment whenever events or changes in circumstances indicate that the assets may not be recoverable. An impairment loss would be recognized when estimated future cash flows expected to result from the use of an asset or asset group and its eventual disposition are less than the carrying amount of the asset or asset group. To date, there have been no such impairment losses. Goodwill Goodwill arose for the acquisition of a business in February 2014 based in Japan and was accounted for as the purchase of a business. Goodwill generated from business combinations and deemed to have indefinite lives are not subject to amortization and instead are tested for impairment at least annually in December unless certain events occur or circumstances change. Goodwill represents the excess of the purchase price over the fair value of the net assets and other identifiable intangible assets acquired. We test for goodwill impairment annually or earlier if events or changes in circumstances indicate goodwill might possibly be impaired. Impairment exists when the carrying value of the goodwill exceeds its implied fair value. An impairment loss would be recognized in an amount equal to that excess as a charge to operations in the unaudited condensed consolidated statements of operations. For the three and nine months ended September 30, 2020 and 2019, no impairment charge was recorded related to goodwill. Intangible Assets Intangible assets that are not considered to have an indefinite useful life are amortized over their estimated useful lives, which generally range from three If it is determined that the carrying values might not be recoverable based upon the existence of one or more indicators of impairment, the Company performs a test for recoverability using various methodologies, such as the income approach or cost approach, to determine the fair value of intangible assets depending upon the nature of the assets. If assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds their respective fair values. For the three and nine months ended September 30, 2020 and 2019, no impairment charges were recorded related to intangible assets. Revenue Recognition Revenue Recognition Policy The Company derives its revenues from sales of high-powered GaN-based products manufactured utilizing the Company’s proprietary and patented epiwafer technology and wafer fabrication and other assembly processes, sales of GaN epiwafers for the radio frequency (“RF”) and power markets, and sales of licenses to use such patented proprietary technology, as well as enabling EPI wafer growth services and products to our strategic partners. Revenues are recognized when control of these products or licenses are transferred to the Company’s customers in an amount that reflects the consideration it expects to be entitled to in exchange for those products and licenses. Sales and other taxes the Company collects concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense. The Company does not have any significant financing components associated with its revenue contracts, as payment is received at or shortly after the point of sale. Disaggregation of Revenue from Contracts with Customers Revenue consists of licensing revenue, government contract revenue from our contract with the U.S. Navy and product sales, with applicable performance obligations satisfied at a point in time. Products are sold to distributors and end-users in various sectors such as, but not limited to, the automotive, gaming, industrial, IT, and consumer products industries. As part of the Collaboration Arrangement (Note 2 - Nexperia Arrangement) executed with Nexperia on April 4, 2018, the Company agreed to grant Nexperia the perpetual exclusive right to use the Company’s existing Gen-3 manufacturing process technology. License fees are received upon satisfaction of contractual milestones and recognized upon delivery of the perpetual license or transferred technology without any remaining performance obligations. The Company recognized $0 and $5.0 million of licensing revenue for the three and nine months ended September 30, 2020, respectively, and no licensing revenue for each of the three and nine months ended September 30, 2019. Additionally, pursuant to agreements entered into in October 2019, during the three and nine months ended September 30, 2020 and 2019, the Company recognized $280,000 and $0 of revenue from the sale of EPI Gen 4 wafer growths. Government contract revenues are principally generated under research and development contracts. Contract revenues are derived primarily from research contracts with agencies of the U.S. government. We believe credit risk related to accounts receivable arising from such contracts is minimal. These contracts may include cost-plus fixed fee and fixed price terms. All payments to us for work performed on contracts with agencies of the U.S. government are subject to adjustment upon audit by the Defense Contract Audit Agency. The Company received new government authorized rates for billing purposes which allowed for retroactive application since inception. The cumulative impact of this rate change was $505 thousand in the third quarter of 2020. The Company will use the new approved rates on go-forward basis. Performance Obligations For performance obligations related to the sale of products, control transfers to the customer at a point in time. The Company’s principal terms of sale are free on board shipping or destination and the Company transfers control and records revenue for product sales upon shipment or delivery to the customer, respectively. For performance obligations related to the licensing of patented technology in perpetuity, control also transfers to the customer at a point in time. The Company transfers control and records revenue for licensing fees once the Company has (i) provided or otherwise makes available the patented technology to the customer and (ii) the customer is able to use and benefit from the patented technology. Variable Consideration The nature of the Company’s arrangement with Nexperia gives rise to variable consideration in the form of milestone and royalty payments. The royalties qualify for the sales and usage-based royalty exception, as the license of intellectual property is the predominant item to which the royalty relates and are recognized upon the subsequent sale occurring. The variable amounts are received upon satisfaction of contractually agreed upon development targets and sales volume. Research and Development The Company is a party to research grant contracts with the U.S. government for which the Company is reimbursed for specified costs incurred for its research projects. These projects include energy saving initiatives for which the U.S. government offers reimbursement funds. Such reimbursements are recorded as an offset to research and development expenses when the related qualified research and development expenses are incurred. Reimbursable costs are recognized in the same period the costs are incurred up to the limit of approved funding amounts on qualified expenses. Grant reimbursement of $81 thousand and $0 was recorded as an offset to research and development expense for the three months ended September 30, 2020 and 2019, respectively. Grant reimbursement of $380 thousand and $0 was recorded as an offset to research and development expense for the nine months ended September 30, 2020 and 2019, respectively. Stock-Based Compensation All share-based payments, including grants of stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”), are measured at the fair value of the share-based awards on the grant date and recognized over their respective vesting periods, which is generally one The Black-Scholes-Merton option pricing model requires inputs such as the fair value of common stock on date of grant, expected term, expected volatility, dividend yield, and risk-free interest rate. Further, the forfeiture rate also affects the amount of aggregate compensation expense. These inputs are subjective and generally require significant analysis and judgment to develop. Volatility data is obtained from a study of publicly traded industry peer companies. The forfeiture rate is derived primarily from the Company’s historical data, and the risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues commensurate with the expected term. Management generally uses the simplified method to calculate the expected term for employee grants as the Company has limited historical exercise data or alternative information to reasonably estimate an expected term assumption. The simplified method assumes that all options will be exercised midway between the weighted average vesting date and the contractual term of the option. Stock-based compensation expense recognized in the Company’s condensed consolidated financial statements is based on awards that are expected to vest. These expense amounts have been reduced by using an estimated forfeiture rate. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company evaluates the assumptions used to estimate forfeitures annually in connection with the recognition of stock-based compensation expense. Loss Per Share Basic loss per share is calculated by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted loss per share is calculated by dividing the net loss attributable to common stockholders by the sum of the weighted average number of common shares outstanding plus potential dilutive common shares outstanding during the period. Potential dilutive securities, comprised of stock warrants, restricted stock units and stock options, are not reflected in diluted loss per share because such shares are anti–dilutive. Dilutive impact of potential common shares resulting from common stock equivalents is determined by applying the treasury stock method. For the three and nine months ended September 30, 2020, there were 3,155,064 shares, consisting of 2,327,423 stock options, 812,180 restricted stock units and 15,461 stock warrants, that were not included in the computation of diluted loss per share because their effect would be anti-dilutive. For the three and nine months ended September 30, 2019, there were 2,469,273 shares, consisting of 2,453,812 stock options and 15,461 stock warrants, that were not included in the computation of diluted loss per share because their effect would be anti-dilutive. Fair Value Measurement Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying values of the Company’s financial instruments such as cash equivalents, accounts receivable, revolving credit facility, accounts payable and accrued liabilities approximate fair values due to the short-term nature of these items. The Company has elected the fair value option for its promissory notes. See Note 3 - Fair Value Measurements. Income Taxes The Company accounts for income taxes in accordance with Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”). ASC 740 prescribes the use of the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement carrying amounts and the tax basis of assets and liabilities and are measured using the enacted statutory tax rates in effect at the balance sheet date. The Company records a valuation allowance to reduce its deferred tax assets when uncertainty regarding their realizability exists. Equity Method Investments The Company uses the equity method to account for investments in entities that it does not control, but in which it has the ability to exercise significant influence over operating and financial policies. The Company's proportionate share of the net income or loss of these companies is included in consolidated net loss. Judgments regarding the level of influence over each equity method investment include consideration of key factors such as the Company's ownership interest, representation on the board of directors or other management body and participation in policy-making decisions. Segment Reporting The Company’s operations and its financial performance is evaluated on a consolidated basis by the chief operating decision maker. Accordingly, the Company considers all of its operations to be aggregated in one reportable operating segment. For the three months ended September 30, 2020, total revenue was $1.9 million, of which $1.6 million was from U.S. operations and $289 thousand was from Japan operations. For the three months ended September 30, 2019, total revenue was $994 thousand, of which $988 thousand was from U.S. operations and $6 thousand was from Japan operations. For the nine months ended September 30, 2020, total revenue was $9.4 million, of which $9.0 million was from U.S. operations and $321 thousand was from Japan operations. For the nine months ended September 30, 2019, total revenue was $2.0 million, of which $2.0 million was from U.S. operations and $25 thousand was from Japan operations. Recently Issued Accounting Standards Adopted Fair Value - In August 2018, the Financial Accounting Standard Boards (“FASB”) issued Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 removes certain disclosures, modifies certain disclosures and adds additional disclosures. ASU 2018-13 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. The Company adopted this standard effective January 1, 2020. The adoption of ASU 2018-13 did not have a material effect on the condensed consolidated financial statements. Statement of Cash Flows - In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows : Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). This guidance addresses eight specific cash flow issues with the objective of reducing existing diversity in practice. ASU 2016-15 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. The Company adopted this standard effective January 1, 2020, using the modified retrospective approach. The adoption of ASU 2016-15 did not have a material effect on the condensed consolidated financial statements. Recently Issued Accounting Standards under Evaluation Leases - In June 2020, the FASB issued ASU 2020-05, which amends the effective dates of the FASB’s standards on leasing (ASC 842) to give immediate relief to certain entities as a result of the widespread adverse economic effects and business disruptions caused by the COVID-19 pandemic. In February 2016, the FASB issued ASU 2016-02, Leases , which, for operating leases, requires the lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, on its balance sheet. The guidance also requires a lessee to recognize single lease costs, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. The leasing standard’s effective dates were the fiscal year beginning after December 15, 2019 as originally issued (ASU 2016-02) and the fiscal year beginning after December 15, 2020 as amended by ASU 2019-10. As amended by ASU 2020-05, the leasing standard’s effective date is now the fiscal year beginning after December 15, 2021. The Company is currently evaluating the impact of this new standard on its condensed consolidated financial statements. Financial Instruments - FASB ASU 2020-03, Codification Improvements to Financial Instruments , makes clear the determination of the contractual life of a net investment in leases in estimating expected credit losses under ASC 326, Financial Instruments – Credit Losses. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). The standard changes the methodology for measuring credit losses on financial instruments and the timing of when such losses ar	Business Transphorm, Inc. develops gallium nitride (“GaN”) semiconductor components used in power conversion. Transphorm was incorporated in the state of Delaware on February 22, 2007. Transphorm, Inc’s activities to date have been primarily performing research and development, establishing manufacturing infrastructure, market sampling, product launch, hiring personnel, and raising capital to support and expand these activities. Transphorm, Inc. is headquartered in Goleta, California. Transphorm Japan, Inc. was established in February 2014 to secure Transphorm, Inc’s production capacity and establish a direct presence in Asian markets. Transphorm Aizu was established to manage the financial transactions around the Joint Venture. Transphorm Epi. was established in 2019 to enable the operational capacity of the reactors held in Aizu. Transphorm, Inc., Transphorm Japan, Inc. and Transphorm Japan Epi, Inc. and Transphorm Aizu are collectively referred to “Transphorm,” the “Company” or “our” in these notes. Stock Conversion On February 12, 2020, the Company entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”). See Note 18 - Subsequent Events for more information. As a result of the Merger, the Company’s stock immediately prior to the closing of the Merger included herein was retroactively restated for the effect of the stock conversion as follows: • Series 1 convertible preferred stock: 51,700,000 shares authorized and 51,680,254 shares issued and outstanding were converted into 12,438,704 shares authorized and 12,433,953 shares issued and outstanding, respectively, as of December 31, 2019 and 2018; • Series 2 convertible preferred stock: 38,800,000 shares authorized and 38,760,190 shares issued and outstanding were converted into 7,507,699 shares authorized and 7,499,996 shares issued and outstanding, respectively, as of December 31, 2019 and 2018; • Series 3 convertible preferred stock: 31,850,304 shares authorized, issued and outstanding were converted into 4,000,000 shares authorized, issued and outstanding as of December 31, 2019 and 2018; and • Common stock: 350,000,000 shares authorized were converted into 29,012,034 shares authorized as of December 31, 2019 and 2018. 50,921,951 shares issued and outstanding were converted into 4,220,998 shares issued and outstanding as of December 31, 2019 and 50,905,160 shares issued and outstanding were converted into 4,219,606 shares issued and outstanding as of December 31, 2018. The stock conversion did not change the par value of our stock. Stock price per share was adjusted in proportion to the decrease in shares to maintain equal value. In addition, stock options and stock warrants are reduced at 1 for 12.063959 rate pursuant to the Merger Agreement and the reduced stock options and stock warrants were retroactively restated for the effect of the stock conversion. Going Concern The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern. As included in the accompanying consolidated financial statements, the Company has generated recurring losses from operations and has an accumulated deficit and has a working capital deficiency. These factors raise substantial doubt about the Company’s ability to continue as a going concern for the next twelve months from the issuance of these consolidated financial statements. Management plans to raise additional working capital to fund operations through the issuance of stock to investors, license of intellectual property and/or issuance of notes payable. The Company raised $19.7 million from the sale of commons stock in February 2020 as described in Note 18 - Subsequent Events. However, there is no assurance that the Company will be successful in raising additional capital. The ability of the Company to continue as a going concern is dependent on its ability to raise adequate capital to fund operating losses until it is able to generate liquidity from its business operations. To the extent sufficient financing is not available, the Company may not be able to, or may be delayed in, developing its offerings and meeting its obligations. The Company will continue to evaluate its projected expenditures relative to its available cash and to evaluate financing alternatives in order to satisfy its working capital and other cash requirements. The accompanying consolidated financial statements do not reflect any adjustments that might result from the outcome of these uncertainties.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements include the accounts of the Transphorm, Inc. and its wholly-owned subsidiaries, Transphorm Japan, Inc., Transphorm Japan Epi, Inc. and Transphorm Aizu, Inc. Upon consolidation, all significant intercompany accounts and transactions have been eliminated. Use of Estimates The preparation of consolidated financial statements in conformity with Accounting Principles Generally Accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates and assumptions on historical experience, knowledge of current conditions, and its belief of what could occur in the future, given available information. Actual results could differ from those estimates, and such differences could be material to the consolidated financial statements. Estimates are used for, but not limited to, the determinations of fair value of stock awards and promissory notes, accrual of liabilities, revenue recognition, inventory reserve, and useful lives for property and equipment. Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported consolidated statements of operations. An adjustment has been made to the consolidated statements of cash flows for the year ended December 31, 2018, to reclass interest expense of $150 thousand to capitalized interest cost. This change in classification does not affect previously reported net cash used in operating activities in the consolidated statements of cash flows. Cash and Cash Equivalents The Company considers all highly-liquid investments with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist principally of bank deposits and money market funds. Other assets in the consolidated balance sheets as of December 31, 2019 and 2018 include cash of $75 thousand. Foreign Currency Risk The Company is exposed to foreign currency risk due to its operations in Japan. Assets and liabilities of the operations are re-measured into U.S. currency at exchange rates in effect at the balance sheet dates through the consolidated statements of comprehensive income. Gains or losses resulting from foreign currency transactions are re-measured using the rates on the dates on which those elements are recognized during the period and are included in other income or expense in the consolidated statements of operations. As of December 31, 2019 and 2018, the Company had foreign cash and cash equivalents of $55 thousand and $264 thousand, respectively, which represent 1.9 percent and 8.6 percent, respectively, of total cash and cash equivalents. Concentrations of Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the financial institution holding its cash. The Company’s investment policy restricts investments to high-quality investments and limits the amounts invested with any one issuer, industry or geographic area. Risks associated with cash holdings in excess of insured limits are mitigated by banking with high-quality institutions. To date, the Company has not experienced any significant losses on its cash and cash equivalents. The Company periodically evaluates the relative credit standing of these financial institutions. The Company is subject to risks common in the power conversion components industry, including, but not limited to, technological obsolescence, dependence on key personnel, market acceptance of its products, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed. Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes the impact of foreign currency translation adjustments. Accounts Receivable Accounts receivable are analyzed and allowances for uncollectible accounts are recorded, as required. Provisions for uncollectible accounts, if any, are recorded as bad debt expense and included in general and administrative expenses in the accompanying consolidated statements of operations. The process for determining the appropriate level of allowances for doubtful accounts involves judgment, and considers such factors as the age of the underlying receivables, historical and projected collection trends, the composition of outstanding receivables, current economic conditions and regulatory changes. An account is fully reserved when reasonable collection efforts have been unsuccessful and it is probable that the receivable will not be recovered. No significant losses on accounts receivable have been recorded as of December 31, 2019 and 2018. Inventory Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value. The Company periodically reviews the value of items in inventory and records write-downs or write-offs based on its assessment of slow moving or obsolete inventory. The Company maintains an inventory reserve for obsolete inventory and generally makes inventory value adjustments against the inventory reserve. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally ranging from three The Company evaluates the carrying amount of its property and equipment whenever events or changes in circumstances indicate that the assets may not be recoverable. An impairment loss would be recognized when estimated future cash flows expected to result from the use of an asset or asset group and its eventual disposition is less than the carrying amount of the asset or asset group. To date, there have been no such impairment losses. Goodwill Goodwill arose for the acquisition of a business in February 2014 based in Japan and was accounted for as the purchase of a business. Goodwill generated from business combinations and deemed to have indefinite lives are not subject to amortization and instead are tested for impairment at least annually in December unless certain events occur or circumstances change. Goodwill represents the excess of the purchase price over the fair value of the net assets and other identifiable intangible assets acquired. We test for goodwill impairment annually or earlier if events or changes in circumstances indicate goodwill might possibly be impaired. Impairment exists when the carrying value of the goodwill exceeds its implied fair value. An impairment loss would be recognized in an amount equal to that excess as a charge to operations in the consolidated statements of operations. For the years ended December 31, 2019 and 2018, no impairment charge was recorded related to goodwill. Intangible Assets Intangible assets that are not considered to have an indefinite useful life are amortized over their estimated useful lives, which generally range from three If it is determined that the carrying values might not be recoverable based upon the existence of one or more indicators of impairment, the Company performs a test for recoverability using various methodologies, such as the income approach or cost approach, to determine the fair value of intangible assets depending upon the nature of the assets. If assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds their respective fair values. For the years ended December 31, 2019 and 2018, no impairment charges were recorded related to intangible assets. Revenue Recognition Revenue Recognition Policy The Company derives its revenues from sales of high-powered GaN-based products manufactured utilizing their proprietary and patented epiwafer technology and wafer fabrication and other assembly processes, and sales of GaN epiwafers for the RF and power markets, as well as sales of licenses to use such patented proprietary technology. Revenues are recognized when control of these products or licenses are transferred to its customers in an amount that reflects the consideration the Company expects to be entitled to in exchange for those products and licenses. Sales and other taxes the Company collects concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense. The Company does not have any significant financing components associated with its revenue contracts, as payment is received at or shortly after the point of sale. Disaggregation of Revenue from Contracts with Customers Revenue for the years ended December 31, 2019 and 2018 consists of licensing revenue, government contract revenue from our contract with the U.S. Navy and product sales, with such performance obligation satisfied at a point in time. Products are sold to distributors and end-users in various sectors such as, but not limited to, the automotive, gaming, industrial, IT, and consumer products industries. As part of the Collaboration Arrangement (Note 3 - Nexperia Arrangement) executed with Nexperia on April 4, 2018, the Company agreed to grant Nexperia the perpetual exclusive right to use the Company’s existing Gen 3 manufacturing process technology. License fees are received upon satisfaction of contractual milestones and recognized upon delivery of the perpetual license or transferred technology without any remaining performance obligations. For the year ended December 31, 2019, the Company received the remaining $6.0 million and recognized a total of $9.0 million, including $3.0 million received in 2018, as licensing revenue upon satisfaction of contractual milestones and delivery of the perpetual license and transferred technology without any remaining performance obligations. For the year ended December 31, 2018, the Company did not recognize any revenue related to the process transfer or technology development performance obligations. The $3.0 million contract liability related to cash received in 2018 from Nexperia is included in deferred revenue. Government contract revenues are principally generated under research and development contracts. Contract revenues are derived primarily from research contracts with agencies of the United States Government. We believe credit risk related to accounts receivable arising from such contracts is minimal. These contracts may include cost-plus fixed fee and fixed price terms. All payments to us for work performed on contracts with agencies of the U.S. Government are subject to adjustment upon audit by the Defense Contract Audit Agency. Performance Obligations For performance obligations related to the sale of products, control transfers to the customer at a point in time. The Company’s principal terms of sale are free on board shipping or destination and the Company transfers control and records revenue for product sales upon shipment or delivery to the customer, respectively. For performance obligations related to the licensing for the use of patented technology in perpetuity, control also transfers to the customer at a point in time. The Company transfers control and records revenue for licensing fees once the Company has (i) provided or otherwise makes available the patented technology to the customer and (ii) the customer is able to use and benefit from the patented technology. Variable Consideration The nature of the Company’s arrangement with Nexperia gives rise to variable consideration in the form of milestone and royalty payments. The royalties qualify for the sales and usage-based royalty exception, as the license of intellectual property is the predominant item to which the royalty relates and are recognized upon the subsequent sale occurring. The variable amounts are received upon satisfaction of contractually agreed upon development targets and sales volume. Research and Development The Company is a party to research grant contracts with the U.S. federal government for which the Company is reimbursed for specified costs incurred for its research projects. These projects include energy saving initiatives for which the U.S. federal government offers reimbursement funds. Such reimbursements are recorded as an offset to research and development expenses when the related qualified research and development expenses are incurred. Reimbursable costs are recognized in the same period the costs are incurred up to the limit of approved funding amounts on qualified expenses. There were no material reimbursements during the years ended December 31, 2019 and 2018 related to cost reimbursement contracts. Stock-Based Compensation All share-based payments, including grants of stock options, are measured based on the fair value of the share-based awards at the grant date and recognized over their respective vesting periods, which is generally four years. The estimated fair value of stock options at the grant date is determined using the Black-Scholes-Merton pricing model. The Company recognizes the fair value of share-based payments as compensation expense for all expected-to-vest stock-based awards over the vesting period of the award using the straight-line attribution method provided that the amount of compensation cost recognized at any date is no less than the portion of the grant-date fair value of the award that is vested at that date. The Black-Scholes-Merton option pricing model requires inputs such as the fair value of common stock on date of grant, expected term, expected volatility, dividend yield, and risk-free interest rate. Further, the forfeiture rate also affects the amount of aggregate compensation expense. These inputs are subjective and generally require significant analysis and judgment to develop. Volatility data is obtained from a study of publicly traded industry peer companies. The forfeiture rate is derived primarily from the Company’s historical data, and the risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues commensurate with the expected term. Management generally uses the simplified method to calculate the expected term for employee grants as the Company has limited historical exercise data or alternative information to reasonably estimate an expected term assumption. The simplified method assumes that all options will be exercised midway between the weighted average vesting date and the contractual term of the option. Stock-based compensation expense recognized in the Company’s consolidated financial statements is based on awards that are expected to vest. These expense amounts have been reduced by using an estimated forfeiture rate. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company evaluates the assumptions used to estimate forfeitures annually in connection of recognition of stock-based compensation expense. Loss Per Share Basic loss per share is calculated by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated by dividing the net income attributable to common stockholders by the sum of the weighted average number of common shares outstanding plus potential dilutive common shares outstanding during the period. Potential dilutive securities, comprised of the convertible preferred stock, stock warrants and stock options, are not reflected in diluted net loss per share because such shares are anti–dilutive. Dilutive impact of potential common shares resulting from common stock equivalents is determined by applying the treasury stock method. For the year ended December 31, 2019, there were 26,422,608 shares, consisting of 23,933,949 convertible preferred stocks, 15,461 stock warrants and 2,473,198 stock options, that were not included in the computation of diluted loss per share because their effect would be anti-dilutive. For the year ended December 31, 2018, there were 26,337,286 shares, consisting of 23,933,949 convertible preferred stocks, 26,157 stock warrants and 2,377,180 stock options, that were not included in the computation of diluted loss per share because their effect would be anti-dilutive. Fair Value Measurement Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying values of the Company’s financial instruments such as cash equivalents, accounts receivable, revolving credit facility, accounts payable and accrued liabilities approximate fair values due to the short-term nature of these items. The Company has elected the fair value option for its promissory notes. See Note 4 - Fair Value Measurements for more information. Income Taxes The Company accounts for income taxes in accordance with Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”). ASC 740 prescribes the use of the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement carrying amounts and the tax basis of assets and liabilities and are measured using the enacted statutory tax rates in effect at the balance sheet date. The Company records a valuation allowance to reduce its deferred tax assets when uncertainty regarding their realizability exists. Equity Method Investments The Company uses the equity method to account for investments in entities that it does not control, but in which it has the ability to exercise significant influence over operating and financial policies. The Company's proportionate share of the net income or loss of these companies is included in consolidated net earnings. Judgments regarding the level of influence over each equity method investment include consideration of key factors such as the Company's ownership interest, representation on the board of directors or other management body and participation in policy-making decisions. Segment Reporting The Company’s operations and its financial performance is evaluated on a consolidated basis by the chief operating decision maker. Accordingly, the Company considers all of its operations to be aggregated in one reportable operating segment. For the year ended December 31, 2019, total revenue was $11.9 million , of which $11.9 million was from U.S. operations and $28 thousand was from Japan operations. For the year ended December 31, 2018, total revenue was $1.4 million, of which $1.3 million was from U.S. operations and $49 thousand was from Japan operations. Recently Issued Accounting Standards Adopted In July 2017, the Financial Accounting Standards Boards (“FASB”) issued Accounting Standards Update (“ASU”) 2017-11, Earnings Per Shares (Topic 260), Distinguishing Liabilities from Equity (Topic 480) and Derivatives and Hedging (Topic 815). ASU 2017-11 changes the classification analysis of certain equity-linked financial instruments, such as warrants and embedded conversion features, such that a down round feature is disregarded when assessing whether the instrument is indexed to an entity’s own stock under Subtopic 815-40. As a result, a down round feature no longer requires an instrument to be remeasured at fair value through earnings each period, although all other aspects of the indexation guidance under Subtopic 815-40 continue to apply. ASU 2017-11 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company adopted this standard, which did not have a material effect on the consolidated financial statements. Stock Compensation - In May 2017, the FASB issued ASU 2017-09, Compensation -Stock Compensation (Topic 718) (“ASU 2017-09”), which clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. ASU 2017-09 is effective for the Company’s 2018 fiscal year, although early adoption is permitted. The Company adopted this standard, which did not have a material effect on the consolidated financial statement. Recently Issued Accounting Standards under Evaluation Income Tax - In December 2019, the FASB issued ASU 2019-12, which modifies ASC 740 to simplify the accounting for income taxes. The ASU’s amendments are based on changes that were suggested by stakeholders as part of the FASB’s simplification initiative (i.e., the Board’s effort to reduce the complexity of accounting standards while maintaining or enhancing the helpfulness of information provided to financial statement users). ASU 2019-12 is effective for the Company’s 2021 fiscal year. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Fair Value - In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 removes certain disclosures, modifies certain disclosures and adds additional disclosures. ASU 2018-13 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Statement of Cash Flows - In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). This guidance addresses eight specific cash flow issues with the objective of reducing existing diversity in practice. ASU 2016-15 is effective for the Company's 2020 fiscal year. The guidance is to be adopted retrospectively unless impracticable upon which the guidance is to be adopted prospectively. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Financial Instruments - In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). The standard changes the methodology for measuring credit losses on financial instruments and the timing of when such losses are recorded. ASU 2016-13 is effective for the Company’s 2021 fiscal year. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Leases - In February 2016, the FASB issued ASU 2016-02, Leases , which, for operating leases, requires the lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, on its balance sheet. The guidance also requires a lessee to recognize single lease costs, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. This guidance will be effective for the Company in fiscal year 2021 and must be adopted using a modified retrospective transition approach. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements.

Nexperia Arrangement

Nexperia Arrangement	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nexperia Arrangement	Nexperia Arrangement Nexperia Transaction On April 4, 2018, the Company entered into a multi-element commercial arrangement with Nexperia B.V. (“Nexperia”) to obtain financing in exchange for the sale of equity instruments and performing certain technology and product development activities for Nexperia (collectively, the “Collaboration Arrangement”). Nexperia specializes in designing, manufacturing and selling a broad range of small discrete semiconductor devices that utilize components such as those manufactured by the Company. Financing under the Collaboration Arrangement is comprised of the following elements: • $16 million Series 3 preferred stock issuance • $9 million license fee for transfer of the Gen-3 manufacturing process • $5 million development loan, originally maturing March 31, 2020 and subsequently extended to June 30, 2020 intended to pre-fund the Gen-4 (Tranche A) technology development (the “Tranche A Loan”) • $10 million development loan maturing March 31, 2021 intended to pre-fund the Gen-5 and 1200V technology development (the “Tranche B Loan”) • $10 million revolving loan (the “Tranche C Loan”) The Company has to use the funds to operate the business in a manner consistent with or reasonably related to those business activities as carried out on or prior to April 4, 2018, the effective date of Collaboration Arrangement. In addition to the multiple elements outlined above, the Company and Nexperia entered into a Supply Agreement requiring that the Company be Nexperia’s primary supplier of specified components until September 30, 2020 on a best efforts basis. By entering into this Collaboration Arrangement, Nexperia will gain access to technology that allows for production of high power semiconductors for use in electric vehicles. Further, Nexperia will obtain an exclusive license and market access to automotive customers outside of Japan and a sole license (non-exclusive of the Company), as well as market access to customers in other parts of the power market. Nexperia has a lien on certain of the Company’s U.S. patents not relating to metal organic chemical vapor deposition (“MOCVD”) or epiwafer technology, per the agreement. On March 31, 2019, the Company executed Amendment No. 1 to the Loan and Security Agreement (the ”LSA”), pursuant to which the Tranche B Loan was bifurcated into the following two separate sub-tranches: • $8 million development loan intended to pre-fund the Gen-5 (Tranche B) technology development (the “Tranche B Loan”) • $2 million development loan intended to pre-fund the 1200V technology development (the “Tranche B-1 Loan” and, together with the Tranche B Loan, the “Tranche B Loans”) On February 7, 2020, Amendment No. 2 to the LSA was executed to acknowledge the then-pending Merger, reaffirm the terms of the loans and confirm the waiver for the late delivery of the Company’s 2018 audited financial statements. On April 8, 2020, Amendment No. 3 to the LSA was executed to extend the maturity of the Tranche A Loan to April 30, 2020. On April 28, 2020, Amendment No. 4 to the LSA was executed to further extend the maturity of the Tranche A Loan to June 30, 2020. All other terms set forth under the original LSA remained unchanged following the amendments. The Tranche A and Tranche B Loans represent pre-funding for Gen-4 (Tranche A), Gen-5 (Tranche B), and 1200V (Tranche B-1) technology development for Nexperia. The specific development activities and associated performance milestones are contained within a Statement of Work (“SoW”) between the Company and Nexperia. The SoW may be modified from time to time based upon mutual business interests. This promise to perform the technology development is a good/service provided to a customer in exchange for consideration in the form of the technology development license fees that offset the Tranche A and Tranche B Loans outstanding. The Development Loans are recognized as a liability equal to the cash proceeds received. In relation to the license fee for the transfer of the Company’s Gen-3 manufacturing process to Nexperia, the Company received $3 million (the first of three tranches) in October 2018, $3 million (the second of three tranches) in April 2019, and $3 million (the third of three tranches) in October 2019. The Company recognized $9.0 million as licensing revenue during 2019 upon the completion of the transfer of the Company’s Gen-3 manufacturing process technology and mutual sign off between Nexperia and the Company. In January 2019, the Company received the $5 million Tranche A Loan. In June 2020, Nexperia agreed that the $5 million Tranche A Loan was permanently satisfied in full in connection with the Company transferring its Gen-4 technology development to Nexperia, at which point the Company recognized $5 million as licensing revenue. In June and July 2019, the Company received the $8 million Tranche B Loan. In December 2019, the Company received the $2 million Tranche B-1 Loan. The Company received the full $10 million Tranche C Loan under the credit facility during the year ended December 31, 2018. See Note 6 - Debts.	Nexperia Arrangement Nexperia Transaction On April 4, 2018, the Company entered into a multi-element commercial arrangement with Nexperia to obtain financing in exchange for sale of equity instruments and performing certain technology and product development activities for Nexperia (collectively, the “Collaboration Arrangement”). Nexperia specializes in designing, manufacturing and selling a broad range of small discrete semiconductor devices that utilize components such as those manufactured by the Company. Financing under the Collaboration Arrangement is comprised of the following elements: • $16 million Series 3 preferred stock issuance • $9 million license fee for transfer of the Gen 3 manufacturing process • $5 million development loan maturing March 31, 2020 intended to pre-fund the Gen 4 (Tranche A) technology development (the “Tranche A Loan”) • $8 million development loan maturing March 31, 2021 intended to pre-fund the Gen 5 (Tranche B), 1200V (Tranche B1) technology development (the “Tranche B Loan”) • $2 million development loan maturing March 31, 2021 intended to pre-fund the 1200V technology development (the “Tranche B-1 Loan”) (together with the Tranche A and Tranche B Loans, the “Development Loans”) • $10 million revolving loan (the “Tranche C Loan”) The Company has to use the funds to operate the business in a manner consistent with or reasonably related to those business activities as carried out on or prior to the Effective Date. In addition to the multiple elements outlined above, the Company and Nexperia entered into a Supply Agreement requiring that the Company be Nexperia’s primary supplier of specified components until June 30, 2020 on a best efforts basis. By entering into this Collaboration Arrangement, Nexperia will gain access to technology that allows for production of high power semiconductors for use in electric vehicles. Further, Nexperia will obtain an exclusive license and market access to automotive customers outside of Japan and a sole license (non-exclusive of the Company), as well as market access, to customers in other parts of the power market. Nexperia has a lien on certain US patents not relating to Metal organic chemical vapor deposition (“MOCVD”) or epiwafer technology, per the agreement. On March 31, 2019, the Company executed Amendment No. 1 to the Loan and Security Agreement (the “First Amendment to the LSA” or the “Amendment”). Under this First Amendment to the LSA, the Tranche B Loan is bifurcated into the following two separate sub-tranches: • $8 million development loan intended to pre-fund the Gen 5 (Tranche B), 1200V (Tranche B1) (Ron/2) technology development (the “Tranche B Loan”) • $2 million development loan intended to pre-fund the 1200V technology development (the “Tranche B-1 Loan” and, together with the Tranche B Loan, the “Tranche B Loans”) All other terms set forth under the original agreement remain unchanged and in full effect. The Tranche A and Tranche B Loans represent pre-funding for Gen 4 (Tranche A), Gen 5 (Tranche B), 1200V (Tranche B1) and 1200V technology development for Nexperia. The specific development activities and associated performance milestones are contained within a Statement of Work (“SoW”) between the Company and Nexperia. The SoW may be modified from time to time based upon mutual business interests. This promise to perform the technology development is a good/service provided to a customer in exchange for consideration in the form of the technology development license fees that offset the Tranche A and Tranche B Loans outstanding. The Development Loans are within the scope of ASC 730-20, Research & Development Arrangements and are recognized as a liability equal to the cash proceeds received. In relation to the transfer of Gen 3 manufacturing process, the Company received $3 million, 1st of the three tranche, in December 2018, $3 million, 2nd of the three tranches, in April 2019, and $3 million, 3rd of the three tranches, in October 2019. Deferred revenue of $3 million was recorded as of December 31, 2018 and the Company recognized this revenue during 2019 upon the completion and mutual sign off between Nexperia and the Company. See Note 17 - Related Party Transactions. In January 2019, the Company received a $5 million development loan maturing March 31, 2020 intended to pre-fund the Gen 4 (Tranche A) technology development (the Tranche A Loan). In June and July 2019, the Company received a $8 million development loan maturing March 31, 2021 intended to pre-fund the Gen 5 (Tranche B), 1200V (Tranche B1) (Ron/2) technology development (the Tranche B Loan). In December 2019, the Company received a $2 million development loan maturing March 31, 2021 intended to pre-fund the 1200V technology development (the “Tranche B-1 Loan”). The Tranche C revolving loan of the full $10 million available under this credit facility was received during the year ended December 31, 2018. See Note 9 - Debts for more information.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements FASB ASC 820, Fair Value Measurements and Disclosures, establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 - Unadjusted quoted prices in active markets for identical assets and liabilities. Level 2 - Inputs (other than quoted prices included within Level 1) that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data of substantially the full term of the related assets or liabilities. Level 3 - Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Inputs are unobservable for the asset or liability. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The following table summarizes the Company’s liabilities measured at fair value as of September 30, 2020 and December 31, 2019, by level within the fair value hierarchy (in thousands) : Level 1 Level 2 Level 3 September 30, 2020 Promissory note $ — $ — $ 16,327 December 31, 2019 Promissory note $ — $ — $ 16,169 The following table includes the changes in fair value of the promissory note which are Level 3 on the fair value hierarchy (in thousands) : 2020 Fair value at January 1, $ 16,169 Interest expense accrued 112 Increase in fair value 46 Fair value at September 30, $ 16,327 2019 Fair value at January 1, $ 15,852 Interest expense accrued 150 Increase in fair value 167 Fair value at December 31, $ 16,169 The Company recorded interest expense of $38 thousand for each of the three months ended September 30, 2020 and 2019, and interest expense of $112 thousand for each of the nine months ended September 30, 2020 and 2019. Fair value of promissory note increased $709 thousand and $17 thousand for the three months ended September 30, 2020 and 2019, respectively, and fair value of promissory note increased $46 thousand and $101 thousand for the nine months ended September 30, 2020 and 2019, respectively. There were no changes to our valuation techniques used to measure assets and liability fair values during the nine months ended September 30, 2020 and 2019. The valuation techniques for the items in the table above are as follows: Level 3 borrowings, which consist of a promissory note, are measured and reported at fair value using a Monte Carlo simulation valuation model. The models can include assumptions related to the value of the notes that are based on the estimated timing and amounts of future rounds of financing, including the estimated timing of a change in control of the Company, and estimated market interest rates, which represent significant unobservable inputs. Assumptions used are (1) the Company is worth today what it can generate in future cash to the Company, (2) cash received today is more than an equal amount of cash received in the future, and (3) future cash flows can be reasonably estimated.	Fair Value Measurements FASB ASC 820, Fair Value Measurements and Disclosures, establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 - Unadjusted quoted prices in active markets for identical assets and liabilities. Level 2 - Inputs (other than quoted prices included within Level 1) that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data of substantially the full term of the related assets or liabilities. Level 3 - Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Inputs are unobservable for the asset or liability. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The following table summarizes the Company’s liabilities measured at fair value as of December 31, 2019 and 2018, by level within the fair value hierarchy ( in thousands ): Level 1 Level 2 Level 3 December 31, 2019 Promissory note $ — $ — $ 16,169 December 31, 2018 Promissory note $ — $ — $ 15,852 The following table includes the changes in fair value of the promissory notes which are Level 3 on the fair value hierarchy ( in thousands ): 2019 2018 Fair value at January 1, $ 15,852 $ 27,756 Interest expense accrued 150 364 Principal and interest expense paid — (13,328) Increase in fair value 167 1,060 Fair value at December 31, $ 16,169 $ 15,852 There were no changes to our valuation techniques used to measure assets and liability fair values during the year ended December 31, 2019 and 2018. The valuation techniques for the items in the table above are as follows: Level 3 borrowings, which consist of promissory notes, are measured and reported at fair value using a Monte Carlo simulation valuation model. The models can include assumptions related to the value of the notes that are based on the estimated timing and amounts of future rounds of financing, including the estimated timing of a change in control of the Company, and estimated market interest rates, which represent significant unobservable inputs. Assumptions used are 1) the Company is worth today what it can generate in future cash to the Company, 2) cash received today is more than an equal amount of cash received in the future; and 3) future cash flows can be reasonably estimated.

Concentration of Credit Risk an

Concentration of Credit Risk and Significant Customers	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Risks and Uncertainties [Abstract]
Concentration of Credit Risk and Significant Customers	Concentration of Credit Risk and Significant Customers The Company manages its credit risk associated with exposure to distributors and direct customers on outstanding accounts receivable through the application of credit approvals and other monitoring procedures. Credit sales, which are mainly on credit terms of 30 to 60 days, are only made to customers who meet the Company's credit standards, while sales to new customers or customers with low credit ratings are usually made on an advance payment basis. The Company closely monitors the aging of accounts receivable from its distributors and direct customers, and regularly reviews their financial positions, where available. Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following table: Revenue for the Nine Months Ended September 30, Accounts Receivable As of 2020 2019 September 30, 2020 December 31, 2019 Customer A 67.3% 14.6% 44.0% 60.0% Customer B 26.0% 51.1% 36.1% 20.4% Customer A is a related party and Customer B is a government agency. See Note 11 - Related Party Transactions.	Concentration of Credit Risk and Significant CustomersThe Company manages its credit risk associated with exposure to distributors and direct customers on outstanding accounts receivable through the application of credit approvals and other monitoring procedures. Credit sales, which are mainly on credit terms of 30 to 60 days, are only made to customers who meet the Company's credit standards, while sales to new customers or customers with low credit ratings are usually made on an advance payment basis. The Company closely monitors the aging of accounts receivable from its distributors and direct customers, and regularly reviews their financial positions, where available. Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following: Revenue for the Year Ended December 31, Accounts Receivable As of December 31, 2019 2018 2019 2018 Customer A * 44.0% * 22.7% Customer B * 17.6% * 43.7% Customer C * 16.0% * * Customer D 79.6% * 60.0% 19.3% Customer E 13.3% * 20.4% * * Less than 10% of total Customer B and D are related parties and customer E is a government agency. See Note 17 - Related Party Transactions for more information.

Inventory

Inventory	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory consists of the following as of September 30, 2020 and December 31, 2019 (in thousands) : As of September 30, 2020 December 31, 2019 Raw materials $ 546 $ 412 Work in process 396 258 Finished goods 430 320 Total $ 1,372 $ 990 An inventory write-off of $112 thousand and $274 thousand was recorded for the three and nine months ended September 30, 2020, respectively. For the three and nine months ended September 30, 2019, no inventory write-off was recorded.	Inventory Inventory consists of the following as of December 31, 2019 and 2018 ( in thousands ): As of December 31, 2019 2018 Raw materials $ 412 $ 258 Work in process 258 270 Finished goods 320 324 Total $ 990 $ 852 For the year ended December 31, 2019 an inventory write-off of $155 thousand was recorded. For the year ended December 31, 2018, no inventory write-off was recorded.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment as of December 31, 2019 and 2018 consists of the following ( in thousands except years ): As of December 31, Estimated Useful Life 2019 2018 Machinery and equipment $ 14,892 $ 14,551 5 Computer equipment and software 876 787 3 Furniture and fixtures 186 185 7 Leasehold improvements (1) 4,954 4,952 7 Construction in progress 6 263 Property and equipment 20,914 20,738 Less: accumulated depreciation and amortization (19,144) (18,606) Property and equipment, net $ 1,770 $ 2,132 (1) Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the related remaining lease term.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The carrying values of intangible assets as of December 31, 2019 and 2018, respectively, consists of the following ( in thousands except years ): December 31, 2019 Gross Accumulated Amortization Foreign Exchange Rate Changes Net Estimated Useful Life Patents $ 2,963 $ (1,679) $ — $ 1,284 10 Developed technology - 150V 560 (519) (34) 7 6 Developed technology - 600V 1,701 (1,575) (104) 22 6 Total $ 5,224 $ (3,773) $ (138) $ 1,313 December 31, 2018 Gross Accumulated Amortization Foreign Exchange Rate Changes Net Estimated Useful Life Patents $ 2,963 $ (1,383) $ — $ 1,580 10 Developed technology - 150V 560 (425) (41) 94 6 Developed technology - 600V 1,701 (1,291) (126) 284 6 Total $ 5,224 $ (3,099) $ (167) $ 1,958 The Company recorded amortization expenses related to intangible assets of $653 thousand and $646 thousand for the years ended December 31, 2019 and 2018, respectively. Estimated future amortization expenses related to intangible assets at December 31, 2019 are as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 325 2021 296 2022 296 2023 296 Thereafter 100 Total $ 1,313

Debts

Debts	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Debts	Debts Development Loans On April 4, 2018, the Company entered into a Loan and Security Agreement (“LSA”) and Development and License Agreement (“DLA”) with Nexperia. The LSA provided for term loans in an aggregate principal amount of up to $15.0 million, which term loans were available in tranches (Tranche A, Tranche B and Tranche B-1) and subject to the satisfaction of specified conditions. The Tranche A Loan of $5.0 million initially was scheduled to mature on the earlier of the date a specified report is required to be delivered under the DLA or March 31, 2020. On April 8, 2020, the maturity of the Tranche A loan was extended to April 30, 2020 and, on April 28, 2020, the maturity of the Tranche A Loan was further extended to June 30, 2020. On June 29, 2020, the Tranche A Loan of $5.0 million was satisfied in full when the Company transferred its Gen-4 technology development to Nexperia. The Tranche B Loan of $8.0 million and Tranche B-1 Loan of $2.0 million mature on the earlier of the date a specified report is required to be delivered under the DLA or March 31, 2021, subject to extension as provided in the LSA. See Note 2 - Nexperia Arrangement. As of September 30, 2020 and December 31, 2019, $10.0 million aggregate principal amount of term loans were outstanding under the LSA. Revolving Credit Facility The LSA also provided a $10.0 million revolving loan (Tranche C Loan) maturing at the earlier of (i) April 3, 2021, and (ii) the date a Change of Control (as defined in the LSA) of the Company occurs. Interest payable by the Company accrues on the outstanding principal amount of the loans during such period at a rate of 6% per annum. The credit facility is secured against certain of our U.S. patents not relating to MOCVD or epiwafer technology. See Note 2 - Nexperia Arrangement. The Tranche C Loan is recorded based on principal in the amount of $10.0 million and accrued interest (6% interest per annum). The Company recorded interest expense of $153 thousand for each of the three months ended September 30, 2020 and 2019, and interest expense of $457 thousand and $455 thousand for the nine months ended September 30, 2020 and 2019, respectively. The Company paid interest expense of $762 thousand during the three months ended September 30, 2020. As of September 30, 2020 and December 31, 2019, the total balance of the revolving credit facility was $10.2 million and $10.5 million, respectively. Promissory Note The Company’s promissory note obligation at September 30, 2020 and December 31, 2019 consists of the following (in thousands) : Stated Value at Interest Rate Due Date September 30, 2020 December 31, 2019 Yaskawa Note 1.00% September 2022 $ 15,448 $ 15,336 Pursuant to ASC 825-10-15-4, the Company elected to apply the fair value option for the promissory note. As of September 30, 2020 and December 31, 2019, the Company determined the fair value for the note, as compared to the face value, including accrued interest, as follows (in thousands) : Fair Value at September 30, 2020 December 31, 2019 Yaskawa Note $ 16,327 $ 16,169 Fair value of promissory note increased $46 thousand for the nine months ended September 30, 2020 and increased $167 thousand for the year ended December 31, 2019. In October 2017, the Company issued an unsecured subordinated convertible promissory note to Yaskawa Electric Corporation (the “Yaskawa Note”) for $15.0 million. The stated interest rate of the Yaskawa Note is 1.0%, and principal plus interest is due on the earlier of September 30, 2022, or the date of the occurrence of an Event of Default, Change of Control or an Initial Public Offering (all terms as defined in the Yaskawa Note). In connection with the Merger, the Yaskawa Note was amended to be convertible at the option of the holder into a maximum of 3,076,171 shares of our common stock at a conversion price of $5.12 per share. In connection with its promissory note obligation, the Company recorded interest expense of $38 thousand for each of the three months ended September 30, 2020 and 2019, and interest expense of $112 thousand for each of the nine months ended September 30, 2020 and 2019. In accordance with the terms of the promissory note, interest is added to the principal balance and is reflected in the carrying value on the condensed consolidated balance sheet. As of September 30, 2020 and December 31, 2019, accrued interest on the promissory note was $448 thousand and $336 thousand, respectively. In February 2020, the Company entered into a letter of intent (“LOI”) with Yaskawa that will form the basis for a mutually beneficial cooperation agreement between the Company and Yaskawa, which is expected to be finalized by the end of 2020. Under the LOI, Yaskawa intends to enter into a long-term cooperation and development agreement with the Company to use the Company’s GaN power device products for a variety of industrial power conversion applications, which will initially focus on servo motor drive applications. Yaskawa also intends to provide at least $4.0 million to fund the Company’s development activities from which amount Yaskawa intends to provide $1.0 million in 2020 in connection with the ongoing development activities. As of September 30, 2020, the scheduled maturity on the development loans, revolving credit facility and promissory note was as follows (in thousands) : Year Ending December 31, Amount 2020 $ 10,153 2021 10,000 2022 15,748 Total $ 35,901	Debts Development Loans On April 4, 2018, the Company entered into a Loan and Security Agreement (“LSA”) with Nexperia. The LSA provided for term loans in an aggregate principal amount of up to $15.0 million, which term loans are available in tranches (Tranche A, Tranche B and Tranche B-1) and subject to the satisfaction of specified conditions. The Tranche A Loan matures on the earlier of the date a specified report is required to be delivered under the DLA or March 31, 2020, subject to extension as provided in the LSA. The Tranche B Loan and Tranche B-1 Loan matures on the earlier of the date a specified report is required to be delivered under the DLA or March 31, 2021, subject to extension as provided in the LSA. See Note 3 - Nexperia Arrangement for more information. For the year ended December 31, 2019, the Company had drawn the full $15.0 million available under the LSA and, as of December 31, 2019, $15.0 million aggregate principal amount of term loans were outstanding under the LSA. Revolving Credit Facility The LSA provided a $10.0 million revolving loan (Tranche C Loan) maturing at the earlier of (i) the third anniversary of April 3, 2018, and (ii) the date a Change of Control (as defined in the Loan and Security Agreement) occurs. Interest payable by the Company will accrue on the outstanding principal amount of the loans during such period at a rate of 6% per annum. The credit facility is secured against certain of our US patents not relating to MOCVD or epiwafer technology. See Note 3 - Nexperia Arrangement for more information. The Nexperia debt is recorded based on principal of $10.0 million and accrued interest (6% interest per annum). The Company recorded interest expense of $608 thousand and $346 thousand for the years ended December 31, 2019 and 2018, respectively. The Company paid interest expense of $496 thousand and zero for the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019 and 2018, total balances of the revolving credit facility were $10.5 million and $10.3 million, respectively. Promissory Note The Company’s promissory note obligation at December 31, 2019 and 2018 consists of the following ( in thousands ): Stated Value at December 31, Interest Rate Due Date 2019 2018 Yaskawa Note 1.00% September 2022 $ 15,336 $ 15,186 Pursuant to ASC 825-10-15-4, the Company elected to apply the fair value option for the promissory note. As of December 31, 2019 and 2018, the Company determined the fair value for the note, as compared to the face value, including accrued interest, as follows ( in thousands ): Fair Value at December 31, 2019 2018 Yaskawa Note $ 16,169 $ 15,852 The changes in fair value of $167 thousand and $1.1 million were recorded in changes in fair value of promissory notes in the accompanying consolidated statements of operations for the years ended December 31, 2019 and 2018, respectively. Prior to January 1, 2016, the Company issued promissory notes to Semiconductor Components Industries, LLC, a semiconductor components manufacturer (the SCI Note), for $10.0 million and to IIDA Electronics Co, Ltd., a Japanese electronics company (the IIDA Note) for $3.0 million. The stated interest rate of the SCI Note is 6.0%, and principal plus interest was due on the earlier of October 2, 2017 or the occurrence of an Event of Default or a Change of Control (both terms as defined). The stated interest rate of the IIDA Note is 1.0%, and principal plus interest is due on the earlier of April 1, 2018, or the date of the occurrence of an Event of Default or a Change of Control (both terms as defined). The IIDA Note was convertible at the option of the holder into shares of common shares at an exercise price of $9.82380 per share. The SCI Note and IIDA Note do not have embedded conversion option as they are accounted for at fair value. In April 2018, both the SCI Note and IIDA Note were paid in full, including accrued interest. In October 2017, the Company issued an unsecured subordinated convertible promissory note to Yaskawa Electric Corporation, (the Yaskawa Note), for $15.0 million. The stated interest rate of the Yaskawa Note is 1.0%, and principal plus interest is due on the earlier of September 30, 2022, or the date of the occurrence of an Event of Default, Change of Control or an Initial Public Offering (all terms as defined). The Yaskawa Note is convertible at the option of the holder into shares of preferred stock upon the consummation of a preferred stock financing, whose aggregate gross proceeds are at least $10.0 million (Qualified Financing), under the terms of such financing, with the following conversion price per share: a) upon the first Qualified Financing that occurs and prior to a second Qualified Financing, a price per share equal to the price per share paid by the purchasers of the preferred stock and b) each subsequent Qualified Financing, a price per share equal to eighty percent (80%) of the price paid by the purchasers of the preferred stock, subject to a upper and lower limit of $250.0 million and $160.0 million estimated enterprise value, each, respectively, divided by the Fully Diluted Capitalization, as defined, of the Company. In connection with its promissory note obligation, the Company recorded interest expense of $150 thousand and $364 thousand for the years ended December 31, 2019 and 2018, respectively. In accordance with the terms of the promissory notes, interest is added to the principal balance and is reflected in the carrying value on the consolidated balance sheet. As of December 31, 2019 and 2018, accrued interest on the promissory notes was $336 thousand and $186 thousand. As of December 31, 2019, the scheduled maturity on the development loans, revolving credit facility and promissory note was as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 15,458 2021 10,000 2022 15,748 Total $ 41,206

Investment in Aizu Fujitsu Semi

Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited ("AFSW")	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investment in Aizu Fujitsu Semiconductor Water Solution Limited ("AFSW")	Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited (“AFSW”) The Company has a 49% interest in AFSW and is a party to a joint venture agreement (the “JVA”) with Fujitsu Semiconductor Limited (“FSL”), the 51% owner of AFSW. AFSW manufactures semiconductor products exclusively for its owners under manufacturing agreements at prices estimated to cover the cost of production. AFSW was determined to be a variable interest entity (“VIE”) as the equity at risk was not believed to be sufficient. AFSW depends on its owners for any additional cash. The Company extended $5.3 million and $2.7 million to AFSW to fund AFSW’s operations for the nine months ended September 30, 2020 and the year ended December 31, 2019, respectively. The Company’s known maximum exposure to loss approximated the carrying value of its investment balance, which included the financing. Potential future losses could be higher than the carrying amount of the Company’s investment, as we are liable, along with the other owner, for other future operating costs or obligations of AFSW. In addition, because Transphorm is currently committed to purchasing GaN wafers and production-related services from AFSW at pre-agreed pricing based upon the Company’s second generation products, the Company may be required to purchase products at a higher cost for its newer generation products. Unfunded commitment to AFSW was $1.7 million as of September 30, 2020 and December 31, 2019. On April 1, 2020, FSL exercised its put option under the JVA and notified us that FSL intended to exit the joint venture by selling its 51% interest in AFSW to us. Under the terms of the JVA, the aggregate purchase price for FSL’s interest in AFSW is expected to be one Japanese Yen. While the agreement provides that completion of the transaction was to take place as soon as 60 days from the date of the exercise notice, such transaction will be subject to regulatory and other approvals in Japan, which we believe will take an additional three The Company’s investment activities in AFSW for the nine months ended September 30, 2020 and the year ended December 31, 2019 are summarized below (in thousands) : For the Nine Months Ended September 30, 2020 For the Year Ended December 31, 2019 Beginning balance $ (1,688) $ (659) Investment 5,327 2,698 Loss (5,218) (3,703) Effect of exchange rate change (105) (24) Ending balance $ (1,684) $ (1,688) Summarized financial information (unaudited) of AFSW for the periods indicated, as provided by the controlling owner, are as follows (in thousands) : As of September 30, 2020 December 31, 2019 Current assets $ 1,138 $ 3,733 Long-term assets $ 5,412 $ 5,101 Other current liabilities $ 2,557 $ 931 Due to controlling owner $ 19,633 $ 17,913 Due to Transphorm $ 10,910 $ 5,349 Net deficit $ (26,550) $ (15,359) Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Sales $ 492 $ 2,613 $ 2,278 $ 8,864 Gross loss $ (3,170) $ (835) $ (8,515) $ (4,002) Net loss $ (3,965) $ (1,585) $ (10,649) $ (6,130)	Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited (“AFSW”) On May 23, 2017, Transphorm acquired a 49% interest in AFSW for 1,000,000 Japanese Yen ($9,000 USD). In connection with the transaction, Transphorm entered into a Joint Venture Agreement (“JVA”) with the 51% owner, Aizu Fujitsu Semiconductor Limited, a subsidiary of Fujitsu Semiconductor Limited. AFSW manufactures semiconductor products exclusively for its owners under manufacturing agreements at prices estimated to cover the cost of production. In connection with the JVA, the Company seconded certain employees from AFSW and entered into a Manufacturing Agreement with AFSW. The JVA provides for certain put and call rights on February 1, 2020 and continue for 180 days thereafter. The 51% owner has the right to put their interest to the Company and the Company can call the other owners interest in AFSW, in either case, for a price, based upon the greater of a formula based upon the increase in net book value or 1 Yen. The Company expects that if either option were to be exercised the price would be 1 Japanese Yen. The Company has determined that the fair value of the put right is not material. The JVA provided that the Company was responsible for the costs and expenses to procure the equipment for wafer processing if solely required for the Company’s gallium nitride products. The JVA provided for monthly payments during the term of the manufacturing agreement for specified equipment and at the conclusion of the payments ownership will transfer to the Company. AFSW was determined to be a variable interest entity (“VIE”) as the equity at risk was not believed to be sufficient. AFSW depends on its owners for any additional cash. In 2019 and 2018, the Company extended $2.7 million and $1.9 million, respectively, to AFSW to fund their operations. The Company’s known maximum exposure to loss approximated the carrying value of our investment balance, which included the financing. Potential future losses could be higher than the carrying amount of the Company’s investment, as they are liable, along with the other owner, for other future operating costs or obligations of AFSW. In addition, because Transphorm is currently committed to purchasing our GaN wafers and production-related services, at pre-agreed pricing based upon our second generation products, the Company may be required to purchase products at a higher cost for its newer generation products. Unfunded commitment to AFSW was $1.7 million and $659 thousand as of December 31, 2019 and 2018, respectively. The Company has determined that they do not have the characteristics of a primary beneficiary in the VIE, and therefore, account for our interest in AFSW using the equity method of accounting. On a quarterly basis the Company will reassess whether our interest in AFSW gives us a controlling financial interest in AFSW. The purpose of this quarterly reassessment is to identify the primary beneficiary of AFSW. The Company determined that they were not the primary beneficiary of the VIE, by virtue of shared non-controlling power with the other owner within AFSW’s Board of Directors, thereby not having the power to direct the activities of AFSW that most significantly impact its economic performance. The Company’ investment activities in AFSW for the years ended December 31, 2019 and 2018 are summarized below ( in thousands ): 2019 2018 Beginning balance at January 1, $ (659) $ (98) Investment 2,698 1,852 Loss (3,703) (2,404) Effect of exchange rate change (24) (9) Ending balance at December 31, $ (1,688) $ (659) Summarized financial information of AFSW as of December 31, 2019 and 2018 and are as follows ( in thousands ) as provided by the controlling owner: As of December 31, 2019 2018 Current assets $ 3,733 $ 4,096 Long-term assets $ 5,101 $ 4,194 Other current liabilities $ 931 $ 961 Due to controlling owner $ 17,913 $ 12,031 Due to Transphorm $ 5,349 $ 2,960 Net deficit $ (15,359) $ (7,662) Year Ended December 31, 2019 2018 Sales $ 11,599 $ 22,283 Gross loss $ (4,849) $ (2,523) Net loss $ (7,557) $ (4,906)

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitment with a Government Agency In connection with a contract with a government agency, the Company entered into a commitment to acquire equipment and services from vendors totaling $6.7 million, all of which is reimbursable. For the three and nine months ended September 30, 2020, the Company received reimbursements of $1.4 million and $5.3 million, respectively, from the government agency. As of September 30, 2020, the remaining commitment under the contract was approximately $1.4 million. For the three and nine months ended September 30, 2020, the Company paid $616 thousand and $4.1 million, respectively, for equipment purchases. As of September 30, 2020, the remaining accounts payable to the vendors was approximately $798 thousand. Operating Leases The Company leases office and fabrication space in Goleta, California, and office spaces in San Jose, California and in Japan under noncancelable operating lease agreements. The terms of certain leases provide for escalating rental payments through the term of the lease. The Company recognizes rent expense on a straight-line basis over the lease term and accrues for rent expense incurred but not paid. As of September 30, 2020, future minimum operating lease commitments were as follows (in thousands) : Year Ending December 31, Amount 2020 $ 180 2021 571 2022 163 Total $ 914 The Company recorded rent expense, net of rental income, which includes common area maintenance fees in addition to the base rent, of $228 thousand and $233 thousand for the three months ended September 30, 2020 and 2019, respectively, and $655 thousand and $672 thousand for the nine months ended September 30, 2020 and 2019, respectively. Rental income from a noncancelable sublease was $45 thousand for each of the three months ended September 30, 2020 and 2019, and $136 thousand for each of the nine months ended September 30, 2020 and 2019. As of September 30, 2020, the future minimum rental payments to be received under the noncancelable sublease are $78 thousand through February 2021. Contingencies During the ordinary course of business, the Company may become a party to legal proceedings incidental to its business. The Company accrues contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. Legal cost is expensed as incurred. The Company is not aware of any material legal claims or assessments. Although the results of litigation and claims are inherently unpredictable, management believes there was not at least a reasonable possibility that the Company had incurred a material loss with respect to any loss contingencies as of September 30, 2020 and through the issuance of these financial statements. Indemnification The Company from time to time enters into types of contracts that contingently require the Company to indemnify parties against third-party claims. These contracts primarily relate to: (1) real estate leases, under which the Company may be required to indemnify property owners for environmental and other liabilities and for other claims arising from the Company’s use of the applicable premises; (2) agreements with the Company’s officers, directors, and employees, under which the Company may be required to indemnify such persons from liabilities arising out of their relationship; (3) indemnifying customers in the event of product failure; and (4) agreements with outside parties that use the Company’s intellectual property, under which the Company may indemnify for copyright or patent infringement related specifically to the use of such intellectual property. Historically, the Company has not been required to make payments under these obligations, and no liabilities have been recorded for these obligations in the Company’s condensed consolidated financial statements.	Commitments and Contingencies Operating Leases The Company leases office and fabrication space in Goleta, California, and office spaces in San Jose, California and in Japan under noncancelable operating lease agreements. The terms of certain leases provide for escalating rental payments through the term of the lease. The Company recognizes rent expense on a straight-line basis over the lease term and accrues for rent expense incurred but not paid. As of December 31, 2019, future minimum operating lease commitments were as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 705 2021 489 2022 163 Total $ 1,357 The Company recorded rent expense, net of rental income, which includes common area maintenance fees in addition to the base rent, of $897 thousand and $915 thousand for the years ended December 31, 2019 and 2018, respectively. Rental income from noncancelable sublease was $182 thousand and $121 thousand for the years ended December 31, 2019 and 2018. As of December 31, 2019, the future minimum rental payments to be received under the noncancelable sublease is $217 thousand through February 2021. Contingencies During the ordinary course of business, the Company may become a party to legal proceedings incidental to its business. The Company accrues contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimable. Legal cost is expensed as incurred. The company is not aware of any material legal claims or assessments, although the results of litigation and claims are inherently unpredictable, management believes there was not at least a reasonable possibility that the Company had incurred a material loss with respect to such loss contingencies as of December 31, 2019 and through date of this report. Indemnification The Company from time to time enters into types of contracts that contingently require the Company to indemnify parties against third-party claims. These contracts primarily relate to: 1) real estate leases, under which the Company may be required to indemnify property owners for environmental and other liabilities and for other claims arising from the Company’s use of the applicable premises; 2) agreements with the Company’s officers, directors, and employees, under which the Company may be required to indemnify such persons from liabilities arising out of their relationship; 3) indemnifying customers in the event of product failure; and 4) agreements with outside parties that use the Company’s intellectual property, under which the Company may indemnify for copyright or patent infringement related specifically to the use of such intellectual property. Historically, the Company has not been required to make payments under these obligations, and no liabilities have been recorded for these obligations in the Company’s consolidated financial statements.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Convertible Preferred Stock	Convertible Preferred Stock As of December 31, 2019 and 2018, the Company’s convertible preferred stock consists of the following ( in thousands, except share and per share data on a post conversion basis ): Authorized Shares Outstanding Shares Carrying Value Par Value per Share Preference Value Series 1 12,438,704 12,433,953 $ 39,658 $ 0.001 $ 40,000 Series 2 7,507,699 7,499,996 30,000 $ 0.001 30,000 Series 3 4,000,000 4,000,000 16,000 $ 0.001 16,000 Total 23,946,403 23,933,949 $ 85,658 $ 86,000 Series 1 and 2 Preferred Stock KKR Phorm Investors L.P. (KKR) purchased 12,433,953 shares of Series 1 preferred stock, par value $0.001 per share, at a per share price of $3.217 for an aggregate purchase price of approximately $40 million. KKR and other investors with a small percentage (~0.02%) purchased 7,499,996 shares of Series 2 preferred stock, par value $0.001 per share, at a per share price of $4.00 for an aggregate purchase price of approximately $30 million. Series 3 Preferred Stock On March 26, 2018, the Company entered into a stock purchase agreement and related contracts in order to effectuate the issuance of its Series 3 preferred stock to Nexperia. Pursuant to the terms of the stock purchase agreement, Nexperia purchased 4,000,000 shares of Series 3 preferred stock, par value $0.001 per share, at a per share price of $4.00, for an aggregate purchase price of approximately $16 million equating to a total ownership stake of approximately 9.9% on a fully-diluted basis. The Company has reserved shares of common stock, par value $0.001 per share, for issuance upon conversion of the Series 3 preferred stock (the conversion shares). The Series 3 preferred stock issued is substantially pari passu with the Company’s Series 1 and Series 2 preferred stock previously issued to KKR with a small percentage (~0.02%) issued to other investors. Each share of Series 1, Series 2 and Series 3 preferred stock are convertible at the option of the holder into such number of shares of common stock as is determined by dividing the original issue price (OIP) of the Series 1, Series 2 and Series 3 preferred stock by the conversion price in effect at the time of the conversion. The conversion price of the Series 1, Series 2 and Series 3 preferred stock is subject to adjustment for certain events. Each share of Series 1, Series 2 and Series 3 preferred stock automatically converts into common stock immediately upon the closing of an underwritten public offering of the Company’s common stock in which the aggregate net proceeds are at least $40 million and the offering price per share is not less than 1.5 times the OIP of the Series 1, Series 2 and Series 3 preferred stock (a Qualifying Public Offering). The rights, privileges, and preferences of the Series 1, Series 2, and Series 3 convertible preferred stock are as follows: Liquidation Rights - In the event of any liquidation, dissolution, or winding up of the Company, either voluntary or involuntary, the holders of convertible preferred stock will be entitled to receive, prior and in preference to any distribution of any assets of the Company to the holders of common stock, an amount per share equal to $3.217 per share for Series 1, $4.00 per share for Series 2 and $4.00 per share for Series 3, plus any declared but unpaid dividends. If, upon the occurrence of such an event, the assets and funds thus distributed among the holders of the convertible preferred stock are insufficient to permit the payment of the preferential amounts, the entire assets and funds legally available for distribution will be distributed ratably among the holders of convertible preferred stock in proportion to the full amount to which they would otherwise be respectively entitled. If, upon satisfaction of the convertible preferred stock preferences, there are any remaining assets and funds available for distribution, they will be ratably distributed among the holders of common stock. Conversion - The convertible preferred stock is convertible at the option of the holder at any time into common stock on a one-for-one basis, subject to certain adjustments for anti-dilution. Each share of convertible preferred stock automatically converts into common stock in the event of an initial public offering (IPO) in which the proceeds are at least $40 million, net of the underwriting discount and commissions, and the offering price per share is not less than 1.5 times the original issue price of the convertible preferred stock unless otherwise agreed to by the shareholders. Dividends - The holders of convertible preferred stock are entitled to receive, out of funds legally available, cash dividends at the rate of $0.25736 per annum for Series 1, $0.32 per annum for Series 2 and $0.32 per annum for Series 3 on each outstanding share. Such dividends are payable when, as, and if declared by the Board of Directors and are noncumulative. Through December 31, 2019, no such dividends have been declared. Voting - The holders of Series 1 convertible preferred stock shall be entitled to the number of votes equal to ten times the number of shares of common stock into which such shares could be converted, and the holders of Series 2 convertible preferred stock shall be entitled to the number of votes equal to the number of shares of common stock into which such shares could be converted. Each holder of Series 3 preferred stock shall be entitled to the number of votes equal to ten times the number of shares of common stock into which the shares of Series 3 preferred stock held by such holder could be converted as of the record date. Due to certain provisions in liquidation and conversion rights the company has presented the convertible preferred stock outside of stockholders deficit as mezzanine equity.

Stockholders' Equity

Stockholders' Equity	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock In March 2018, the Company amended the Certificate of Incorporation, to increase the number of authorized shares of common stock from 24,867,458 to a new total of 29,012,034 shares of $0.001 par value common stock. Common stockholders are entitled to dividends, as and when declared by the Board of Directors, subject to the priority dividend rights of the holders of other classes of stock. There have been no dividends declared to date. The holder of each share of common stock is entitled to one vote. At December 31, 2019, the Company has reserved shares of common stock for future issuance as follows: Conversion of convertible preferred stock 23,946,403 Stock option plans 4,023,826 Common stock warrants 15,461 Total 27,985,690 Common Stock Warrants At December 31, 2019, the following warrants to purchase common stock were outstanding: Number of Shares Exercise Price Expiration Date 6,046 $34.74 November 2020 6,046 $34.74 5 years after an initial public offering of the Company 3,369 $54.41 5 years after an initial public offering of the Company 15,461	Stockholders’ Equity On February 12, 2020, in connection with the Merger, shares of Transphorm Technology’s convertible preferred stock and common stock issued and outstanding immediately prior to the closing of the Merger were converted into shares of the Company’s common stock as follows: • Series 1 convertible preferred stock: 51,680,254 shares issued and outstanding were converted into 12,433,953 shares issued and outstanding; • Series 2 convertible preferred stock: 38,760,190 shares issued and outstanding were converted into 7,499,996 shares issued and outstanding; • Series 3 convertible preferred stock: 31,850,304 issued and outstanding were converted into 4,000,000 shares issued and outstanding; and • Common stock: 50,325,662 shares issued and outstanding were converted into 4,171,571 shares issued and outstanding. In addition, on February 12, 2020, the Company issued 1,650,000 shares in connection with the Merger with Peninsula Acquisition Corporation and redeemed 52,773 shares from unaccredited investors. All per share and share amounts for all periods presented have been retroactively adjusted to reflect the effect of the Merger. In December 2019, the Company amended its certificate of incorporation to authorize two classes of stock, to be designated, respectively, common stock and preferred stock. The total number of shares of stock that the Company shall have authority to issue is 755,000,000 shares, of which 750,000,000 shares are common stock, $0.0001 par value per share, and 5,000,000 shares are preferred stock, $0.0001 par value per share. As of September 30, 2020, 750,000,000 shares of common stock are authorized, of which 35,266,496 shares of common stock were issued and outstanding, and 5,000,000 shares of preferred stock are authorized, none of which were issued and outstanding. The Company’s Board of Directors has the ability to designate the rights, preferences and privileges for the preferred stock. Private Placement On February 12, 2020 and February 27, 2020, we sold an aggregate of 5,380,000 shares of common stock pursuant to closings of a private placement offering (the “Private Placement”) at a purchase price of $4.00 per share. We granted to the investors in the Private Placement registration rights requiring us to register those shares of common stock for public resale. The then existing stockholders of Transphorm Technology also became entitled to such registration rights. The aggregate gross proceeds from the closings of the Private Placement were $21.5 million (before deducting placement agent fees and expenses of such closings, which were an aggregate of $1.8 million). The issuance of common stock in the Private Placement was not registered under the Securities Act, in reliance upon the exemption from registration provided by Section 4(a)(2) of the Securities Act and Rule 506 of Regulation D promulgated by the SEC. The common stock issued in the Private Placement was sold to “accredited investors,” as defined in Regulation D, and was conducted on a “reasonable best efforts” basis. Common Stock Common stockholders are entitled to dividends, as and when declared by the Company’s Board of Directors, subject to the priority dividend rights of the holders of other classes of stock. There have been no dividends declared to date. The holder of each share of common stock is entitled to one vote. At September 30, 2020, the Company has reserved shares of common stock for future issuance as follows: Equity incentive plans 5,042,525 Common stock warrants 15,461 Total 5,057,986 Common Stock Warrants At September 30, 2020, the following warrants to purchase common stock were outstanding: Number of Shares Exercise Price Expiration Date 6,046 $34.74 November 2020 6,046 $34.74 5 years after an initial public offering of the Company 3,369 $54.41 5 years after an initial public offering of the Company 15,461

Stock Option Plans

Stock Option Plans	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock Option Plans	Stock Based Compensation The 2020 Equity Incentive Plan (the “2020 Plan”) was approved by Transphorm Technology’s board of directors on February 10, 2020 and Transphorm Technology’s stockholders on February 12, 2020, and became effective on the business day immediately prior to the closing of the Merger. Our stockholders approved the 2020 Plan on February 11, 2020. We assumed the 2020 Plan in connection with the Merger. As of September 30, 2020, there were 1,902,922 shares available for grant and 816,180 restricted stock units outstanding under the 2020 Plan. The 2020 Plan provides for the grant of incentive stock options, within the meaning of Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”), to our employees and our parent and subsidiary corporations’ employees, and for the grant of nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units (“RSUs”), performance units, and performance shares to our employees, directors, and consultants and our parent and subsidiary corporations’ employees and consultants. Subject to the adjustment provisions of the 2020 Plan, and the automatic increase described in the 2020 Plan, the maximum aggregate number of shares of our common stock that may be issued under the 2020 Plan is 5,050,000 shares of our common stock, which includes (i) 2,588,077 shares initially reserved for issuance, plus (ii) any shares of our common stock subject to issued and outstanding awards under the 2007 Plan or 2015 Plan that were assumed in the Merger and that, on or after the closing of the Merger, expire or otherwise terminate without having been exercised or issued in full, are tendered to or withheld by us for payment of an exercise price or for tax withholding obligations, or are forfeited to or repurchased by us due to failure to vest, with the maximum number of shares to be added to the 2020 Plan pursuant to this clause (ii) equal to 2,461,923 shares. Subject to the adjustment provisions of the 2020 Plan, the number of shares of common stock available for issuance under the 2020 Plan will also include an annual increase on the first day of each fiscal year beginning with our 2022 fiscal year and ending on (and including) our 2030 fiscal year, in an amount equal to the least of: 5,000,000 shares of our common stock; five percent (5%) of the outstanding shares of our common stock on the last day of the immediately preceding fiscal year; or such number of shares of our common stock as the administrator of the 2020 Plan may determine. Stock Options The following table summarizes stock option activity and related information for the three months ended September 30, 2020 and 2019: Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value (1) (in thousands) Balance at July 1, 2020 2,454,687 $ 4.74 6.33 $ — Options exercised (3,475) $ 3.80 Options canceled (123,789) $ 5.91 Balance at September 30, 2020 2,327,423 $ 4.68 6.16 $ 167 Exercisable at September 30, 2020 2,211,723 $ 4.74 6.08 $ 111 Balance at July 1, 2019 2,342,440 $ 4.84 7.16 $ — Options granted 125,183 $ 3.14 Options canceled (13,811) $ 4.58 Balance at September 30, 2019 2,453,812 $ 4.69 7.06 $ — Exercisable at September 30, 2019 1,984,257 $ 4.95 6.85 $ — (1) Intrinsic value represents the excess of the fair value on the last trading day of the period, which was $4.00 as of September 30, 2020, over the exercise price, multiplied by the number of options. The following table summarizes stock option activity and related information for the nine months ended September 30, 2020 and 2019: Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in thousands) Balance at January 1, 2020 2,473,130 $ 4.67 6.84 $ — Options authorized — $ — Options exercised (6,821) $ 3.78 Options canceled (138,886) $ 5.72 Balance at September 30, 2020 2,327,423 $ 4.68 6.16 $ 167 Exercisable at September 30, 2020 2,211,723 $ 4.74 6.08 $ 111 Balance at January 1, 2019 2,377,180 $ 4.83 7.46 $ — Options granted 183,109 $ 3.14 Options canceled (106,477) $ 4.34 Balance at September 30, 2019 2,453,812 $ 4.69 7.06 $ — Exercisable at September 30, 2019 1,984,257 $ 4.95 6.85 $ — (1) Intrinsic value represents the excess of the fair value on the last trading day of the period, which was $4.00 as of September 30, 2020, over the exercise price, multiplied by the number of options. Restricted Stock Restricted Stock Awards RSAs are grants of shares of our common stock that vest in accordance with terms and conditions established by the Company’s Board of Directors. Recipients of RSAs generally will have voting and dividend rights with respect to such shares upon grant without regard to vesting, unless the RSA agreement provides otherwise. Shares of restricted stock that do not vest are subject to forfeiture. In September 2020, we granted 123,501 RSAs outside of our 2020 Plan. Seventy percent of these RSAs was vested on the date of grant and the remainder is scheduled to vest 120 days following the grant date. The following table summarizes RSA activity and related information for the three and nine months ended September 30, 2020: September 30, 2020 Three Months Ended Nine Months Ended Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Balance at beginning of period — $ — — $ — Granted 123,501 $ 4.00 123,501 $ 4.00 Vested (86,450) $ 4.00 (86,450) $ 4.00 Balance at end of period 37,051 $ 4.00 37,051 $ 4.00 Restricted Stock Units RSUs are grants of shares of our common stock that vest in accordance with terms and conditions established by the administrator of the 2020 Plan. Subject to the provisions of the 2020 Plan, the administrator determines the terms and conditions of RSUs, including the vesting criteria. We granted 816,180 RSUs during the third quarter of 2020, 4,000 of which were fully vested on the date of grant. The remainder of the RSUs are scheduled to vest as follows: one third will vest on each of January 1, 2022, January 1, 2023 and July 1, 2023, in each case subject to the RSU holders’ continued status as a service provider to the Company through each vesting date. The following table summarizes RSU activity and related information for the three and nine months ended September 30, 2020: September 30, 2020 Three Months Ended Nine Months Ended Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Balance at beginning of period — $ — — $ — Granted 816,180 $ 4.00 816,180 $ 4.00 Vested (4,000) $ 4.00 (4,000) $ 4.00 Balance at end of period 812,180 $ 4.00 812,180 $ 4.00 Stock-Based Compensation The accompanying condensed consolidated statement of operations and comprehensive loss includes stock-based compensation expense as follows (in thousands) : Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenue $ 17 $ 24 $ 43 $ 44 Research and development 62 60 148 146 Sales and marketing 11 8 23 24 General and administrative 494 67 606 221 Total $ 584 $ 159 $ 820 $ 435 Unrecognized Stock-Based Compensation Unrecognized stock-based compensation expense was as follows (in thousands) : As of September 30, 2020 As of September 30, 2019 Unrecognized Expense Average Expected Recognition Period Unrecognized Expense Average Expected Recognition Period Stock options $ 113 0.87 years $ 573 1.34 years Restricted stock $ 3,297 2.64 years — — Total $ 3,410 2.43 years $ 573 1.34 years	Stock Option Plans In 2007, the Board of Directors adopted the 2007 Stock Option Plan (the 2007 Plan). The 2007 Plan provides for the granting of incentive and non-statutory stock options to employees, officers, directors and consultants of the Company. Stock options are generally granted with terms of up to 10 years and with a strike price equal to or greater than the fair value on the date of grant, as determined by the Board of Directors. The 2007 Plan provides for standard vesting of stock options of 25% after 12 months and 1/36th of the remaining balance monthly. Effective June 2015, no additional grants were available under the 2007 Plan. As of December 31, 2019, 165,983 shares were issued and outstanding under the 2007 plan. In June 2015, the Board of Directors adopted the 2015 Equity Incentive Plan (the 2015 Plan). The 2015 Plan provides for the granting of incentive and nonstatutory stock options to purchase the Company’s common stock, stock appreciation rights, restricted stock and restricted stock units to employees, directors and consultants of the Company. Under the terms of the 2015 Plan, stock options and stock appreciation rights may be granted with terms of up to 10 years at exercise prices of no less than 100% of the fair market value of the Company’s common stock on the grant date. As of December 31, 2019, 2,307,215 shares were issued and outstanding under the 2015 plan. The following table summarizes stock option activity under the 2007 Plan and 2015 Plan and related information: Number of Shares Available for Grant Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value Balance at January 1, 2018 1,589,381 2,435,837 $ 4.80 8.38 $ — Options granted (46,005) 46,005 $ 4.34 Options canceled 104,662 (104,662) $ 4.70 Balance at December 31, 2018 1,648,038 2,377,180 $ 4.79 7.46 $ — Options granted (209,908) 209,908 $ 3.14 Options exercised — (1,392) $ 3.86 Options canceled 112,498 (112,498) $ 4.34 Balance at December 31, 2019 1,550,628 2,473,198 $ 4.67 6.84 $ — Exercisable at December 31, 2019 2,079,809 $ 4.95 6.65 $ — Stock-based compensation expense is determined based on the fair value of the Company’s common stock as determined by the Board of Directors and assumptions such as volatility, expected term, risk-free interest rates, and other factors. Changes in the deemed fair value of the common stock, the underlying assumptions in the calculations, the number of options granted or the terms of such options, the expected forfeiture rate, the treatment of tax benefits and other changes may result in significant differences in the amounts or timing of the compensation expense recognized. The assumptions and estimates are made as follows: • Fair Value of Common Stock - The fair value of the shares of common stock underlying the stock options has been determined by the Board of Directors, utilizing valuation studies performed by third-party advisors. Because there has been no public market for the Company’s common stock, the Board of Directors has determined fair value of the common stock at the time of grant of the options by considering a number of objective and subjective factors, including valuations of comparable companies, sales of convertible preferred stock to unrelated third parties, operating and financial performance, the lack of liquidity of capital stock, and general and industry-specific economic outlook. The Company has not granted stock options with an exercise price that is less than the fair value of the underlying common stock as determined at the time of grant by the Board of Directors. • Expected Volatility - The Company utilizes the historical volatility of representative public companies to determine its expected volatility, as there is no public trading of the Company’s common stock. • Estimated Forfeitures - The Company adopted ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting and has elected to account for forfeitures as they occur and therefore, stock-based compensation expense for the year ended December 31, 2019 has been calculated based on actual forfeitures in the statements of operations, rather than our previous approach which was net of estimated forfeitures. The net cumulative effect of this change was not material. • Expected Dividend Yield - The Company has not issued any common stock dividends; therefore, a dividend yield of zero was used. • Risk-Free Interest Rate - The Company bases the risk-free interest rate used in the Black- Scholes-Merton option pricing model on the implied yield currently available on United States Treasury zero-coupon issues with an equivalent expected term. • Expected Term - The expected term of stock options represents the period that the Company’s stock options are expected to be outstanding. The Company generally uses the simplified method to calculate the expected term for employee grants. The assumptions used to value options granted to employees during the year ended December 31, 2019 and 2018, were as follows: Year Ended December 31, 2019 2018 Weighted average expected life (in years) 5.46 5.84 Risk-free interest rate 1.34% - 1.94% 2.51% - 2.52% Expected volatility 39.4% - 39.8% 38.1% - 38.2% Weighted average grant date fair value $1.04 $0.84 Dividend yield —% —% As of December 31, 2019, there was $464 thousand of unrecognized stock-based compensation cost related to stock options granted to employees under the 2007 Plan and the 2015 Plan. The unrecognized compensation cost is expected to be recognized over an estimated weighted average amortization period of 1.2 years. The accompanying consolidated statement of operations includes stock-based compensation expense as follows ( in thousands ): Year Ended December 31, 2019 2018 Cost of revenue $ 60 $ 41 Research and development 196 186 Sales and marketing 30 45 General and administrative 280 313 Total $ 566 $ 585

401(k) Savings Plan

401(k) Savings Plan	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
401(k) Savings Plan	401(k) Savings Plan    The Company has a 401(k) savings plan (the 401(k) plan). The 401(k) plan is a defined contribution plan intended to qualify under Section 401(k) of the Internal Revenue Code. All full-time employees of the Company are eligible to participate pursuant to the terms of the 401(k) plan. Contributions by the Company are discretionary, and the Company made no contributions during the years ended December 31, 2019 and 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the year ended December 31, 2019, the Company reported a worldwide consolidated pre-tax loss of $15.3 million, which consisted of a pre-tax loss from U.S. operations of approximately $10.6 million and pre-tax loss from Japan operations of approximately $4.7 million. The pre-tax loss from Japan operations consists of a $1.0 million pre-tax loss from Transphorm Japan, Inc., a $3.7 million pre-tax loss from Transphorm Aizu, Inc. and a $1 thousand pre-tax income from Transphorm Epi, Inc. For the year ended December 31, 2018, the Company reported a worldwide consolidated pre-tax loss of $25.8 million, which consisted of a pre-tax loss from U.S. operations of approximately $22.1 million, pre-tax loss from Transphorm Japan, Inc. operations of approximately $1.3 million and a pre-tax loss from Transphorm Aizu, Inc. operations of approximately $2.4 million. There is no U.S. federal or foreign provision for income taxes because the Company has incurred operating losses since inception and is in a full valuation allowance position. For the years ended December 31, 2019 and 2018, the Company has recorded a state income tax provision of $1 thousand which represents minimum taxes. Deferred income taxes reflect the net tax effects of the net operating losses and the temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets and deferred tax liabilities are as follows ( in thousands ): As of December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 43,973 $ 42,181 Tax credits 4,535 3,808 California capitalized research and development 343 290 Depreciation — 153 Others, net 602 318 Total deferred tax assets 49,453 46,750 Valuation allowance (49,403) (46,749) Deferred tax asset, net of valuation allowance 50 1 Deferred tax liabilities: Others, net — (1) Fixed assets (50) — Total deferred tax liabilities (50) (1) Net deferred tax assets $ — $ — As of December 31, 2019 and 2018, the Company had no assurance that future taxable income would be sufficient to fully utilize the net operating loss carryforwards and other deferred tax assets in the future. Consequently, the Company determined that a valuation allowance of approximately $49.4 million and $46.7 million as of December 31, 2019 and 2018, respectively, was needed to offset the deferred tax assets resulting mainly from the net operating loss carryforwards. As such, for the years ended December 31, 2019 and 2018, the Company recorded an additional valuation allowance of $2.7 million and $6.4 million, respectively. The Company files income tax returns in the U.S. federal, California, and Oregon jurisdictions and is subject to U.S. federal, state, and local income tax examinations by tax authorities. Generally, the statute of limitations is 3 years for U.S. federal income tax and 4 years for state and local taxes. The statute of limitations may be extended for tax years where a corporation has a net operating loss carryforward or by agreement with the jurisdictional taxing authority. Accordingly, all of the Company's U.S. federal, state and local income tax years since inception remain open to examination by tax authorities. The Company is not currently under audit by any taxing authority. The Company follows the provisions of uncertain tax positions as addressed in ASC 740-10. The Company recognized no increase or decrease in the liability for unrecognized tax benefits for any period presented. The Company recognizes interest accrued related to unrecognized tax benefits in interest expense and penalties in operating expenses. No such interest or penalties were recognized during the period presented. The Company had no accruals for interest and penalties at December 31, 2019 and 2018. The utilization of the Company’s net operating loss and tax credit carryforwards is dependent on the future profitability of the Company. Further, the Internal Revenue Code imposes substantial restrictions on the utilization of such carryforwards in the event of an ownership change of more than 50%, as defined, during any three-year period (Section 382 and 383 limitations). The Company has determined that several ownership changes have occurred, which have resulted in substantial limitations on the Company’s ability to utilize its pre-ownership change net operating loss and tax credit carryforwards. These substantial limitations are expected to result in both a permanent loss of certain tax benefits related to net operating loss carryforwards and federal research and development credits, as well as an annual utilization limitation. The Company performed an analysis through a private placement offering and anticipates no further Section 382 and 383 limitations. As of December 31, 2019, the Company has federal net operating loss carryforwards of $234.8 million, of which $207.5 million will begin to expire in 2027 unless previously utilized, and the Company has state net operating loss carryforwards of $152.7 million which will begin to expire in 2028 unless previously utilized. The Company also has foreign net operating loss carryforwards of approximately $4.6 million which will begin to expire in 2024. The federal net operating loss generated for the years ended 2019 of $8.8 million and 2018 of $18.5 million can be carried forward indefinitely. However, the federal deduction for net operating losses incurred in tax years beginning after January 1, 2018 is limited to 80% of annual taxable income. The state net operating loss generated for the years ended 2019 of $5.1 million and 2018 of $15.3 million can be carried forward 20 years. As of December 31, 2019, the Company has federal research and development credit carryforwards of $4.1 million, which will begin to expire in 2032 unless previously utilized, and the Company had California research and development credit carryforwards of $2.7 million, which do not expire. Deferred tax assets have not been established for net operating and tax credit carryforwards that are deemed to have no value due to the Section 382 and 383 limitations discussed above and, therefore, are not reflected in the table of deferred tax assets presented above. Future ownership changes, if any, may further limit the Company’s ability to utilize its remaining net operating losses and tax credit carryforwards. The Company performed an analysis through a private placement offering and anticipates no further Section 382 and 383 limitations. Reconciliation between federal statutory tax rate and the effective tax rate is shown in the following table: Year Ended December 31, 2019 2018 Federal statutory income tax rate 21.00% 21.00% Research and development credit 4.76% 1.61% Nondeductible expenses (3.18)% (1.81)% Loss in joint venture (7.44)% (1.99)% Foreign income tax rate difference 2.99% (1.04)% Others, net (0.78)% 0.02% Valuation allowance (17.35)% (17.79)% Effective tax rate —% —%

Related Party Transactions

Related Party Transactions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions During the year ended December 31, 2019, the Company entered into the following related party transactions: • Recorded $211 thousand in cost of goods sold for services, recorded research and development expense of $695 thousand, of which $195 thousand was reimbursable, recorded $444 thousand in other expense for commitment for services, and incurred $14 thousand for employees and their related benefits seconded from the joint venture with AFSW; • Sold $241 thousand of products to non-controlling common stockholders of the Company and incurred $200 thousand of license maintenance fee from a non-controlling common stockholder of the Company; • Incurred $21 thousand for employees and their related benefits seconded from a common stockholder of the Company; and • Recorded $9.2 million in license fee income, recorded $195 thousand reimbursement for research and development, and sold $504 thousand of products to a convertible preferred stockholder of the Company. See Note 3 - Nexperia Arrangements. As of December 31, 2019, total accounts receivable from related parties was $5.8 million, consisting of $5.3 million from the joint venture with AFSW, $38 thousand from non-controlling common stockholders of the Company and $426 thousand from a convertible preferred stockholder and noteholder of the Company. As of December 31, 2019, total accounts payable to related parties was $272 thousand to non-controlling common stockholders of the Company. During the year ended December 31, 2018, the Company entered into the following related party transactions: • Recorded $751 thousand in cost of goods sold for services, incurred expenses of $560 thousand for research and development activities, and incurred $175 thousand for employees and their related benefits seconded from the joint venture with AFSW; • Sold $269 thousand of products to non-controlling common stockholders of the Company and incurred $200 thousand of license maintenance fee from a non-controlling common stockholder of the Company; • Incurred $71 thousand for employees and their related benefits seconded from a common stockholder of the Company; • Sold $37 thousand of products to common stockholders and former noteholders of the Company; and • Recorded $3.0 million in deferred license fee and sold $166 thousand of products to a convertible preferred stockholder of the Company. As of December 31, 2018, total accounts receivable from related parties was $3.1 million, consisting of $3.0 million from the joint venture with AFSW, $123 thousand from non-controlling common stockholders of the Company, $10 thousand from non-controlling common stockholder and noteholder of the Company and $54 thousand from a convertible preferred stockholder and noteholder of the Company. As of December 31, 2018, total accounts payable to related parties was $122 thousand to non-controlling common stockholders of the Company.	Related Party Transactions During the three months ended September 30, 2020, the Company entered into the following related party transactions: • Recorded $60 thousand in cost of goods sold for services, recorded research and development expense of $418 thousand and recorded $10 thousand in payroll related cost from the AFSW joint venture; • Sold $113 thousand of products to non-controlling stockholders of the Company and incurred $50 thousand of license maintenance fee from a non-controlling stockholder of the Company; and • Recorded $31 thousand in license fee income, recorded $280 thousand in EPI Gen 4 wafer growth sales, recorded $38 thousand of reimbursements in license maintenance fee, recorded $153 thousand in interest expense and sold $174 thousand of products to a stockholder and noteholder of the Company. See Note 2 - Nexperia Arrangement. During the nine months ended September 30, 2020, the Company entered into the following related party transactions: • Recorded $228 thousand in cost of goods sold for services, recorded research and development expense of $1.1 million, of which $408 thousand was reimbursable, recorded $84 thousand in other expense for commitment for services, and recorded $11 thousand in payroll related cost from the AFSW joint venture; • Sold $153 thousand of products to non-controlling stockholders of the Company and incurred $150 thousand of license maintenance fee from a non-controlling stockholder of the Company; and • Recorded $5.1 million in license fee income, recorded $280 thousand in EPI Gen 4 wafer growth sales, recorded $113 thousand of reimbursements in license maintenance fee, recorded $457 thousand in interest expense, recorded $408 thousand reimbursement for research and development, and sold $877 thousand of products to a stockholder and noteholder of the Company. See Note 2 - Nexperia Arrangement. As of September 30, 2020, total due from related parties was $12.3 million, consisting of $11.3 million due from the AFSW joint venture, $113 thousand accounts receivable from non-controlling stockholders of the Company, and $532 thousand accounts receivable and $338 thousand other receivable from a stockholder and noteholder of the Company. As of September 30, 2020, total accounts payable to related parties was $434 thousand to the AFSW joint venture. During the three months ended September 30, 2019, the Company entered into the following related party transactions: • Recorded $379 thousand in cost of goods sold for services, recorded research and development expense of $117 thousand, and incurred $6 thousand for employees and their benefits seconded from the AFSW joint venture; • Sold $58 thousand of products to non-controlling stockholders of the Company; and • Recorded $16.0 million of reimbursements in license maintenance fee, incurred $38 thousand of license maintenance fee, recorded $153 thousand in interest expense and sold $178 thousand of products to a stockholder and noteholder of the Company. See Note 2- Nexperia Arrangement. During the nine months ended September 30, 2019, the Company entered into the following related party transactions: • Recorded $477 thousand in cost of goods sold for services, recorded research and development expense of $320 thousand, and incurred $21 thousand for employees and their benefits seconded from the AFSW joint venture; • Sold $216 thousand of products to non-controlling stockholders of the Company, incurred $100 thousand of license maintenance fee to a non-controlling stockholder, and incurred $21 thousand for employees and their related benefits seconded from a non-controlling stockholder of the Company; and • Recorded $16.0 million in unearned revenue for sales, recorded $113 thousand of reimbursements in license maintenance fee, recorded $455 thousand in interest expense and sold $293 thousand of products to a stockholder and noteholder of the Company. See Note 2- Nexperia Arrangement. As of December 31, 2019, total due from related parties was $5.8 million, consisting of $5.3 million due from the AFSW joint venture, $38 thousand accounts receivable from non-controlling stockholders of the Company and $426 thousand accounts receivable from a stockholder and noteholder of the Company. As of December 31, 2019, total accounts payable due to related parties was $272 thousand to non-controlling stockholders of the Company.

Subsequent Events

Subsequent Events	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsThe Company has evaluated subsequent events through the issuance of these financial statements and is not aware of any material items that would require disclosure in the notes to the financial statements or would be required to be recognized as of September 30, 2020.	Subsequent Events The Company has evaluated subsequent events through the issuance of these financial statements, and determined that there have been no events that have occurred that would require adjustments to our disclosures in the consolidated financial statements except for the following: Merger Agreement On February 12, 2020, Peninsula Acquisition Corporation, Acquisition Sub and Transphorm Technology entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”). Pursuant to the terms of the Merger Agreement, on February 12, 2020, Acquisition Sub merged with and into Transphorm Technology, with Transphorm Technology continuing as the surviving corporation and a wholly-owned subsidiary of Peninsula Acquisition Corporation. The Merger was treated as a recapitalization and reverse acquisition for financial reporting purposes. Transphorm Technology is considered the acquirer for accounting purposes. Immediately after completion of the merger, Peninsula Acquisition Corporation adopted Transphorm Technology’s former company name, Transphorm, Inc. as its company name. Private Placement Following the Merger, the Company sold 5,365,000 shares of common stock pursuant to an initial closing of a private placement offering (“Offering”) for up to 12,500,000 shares of common stock at a purchase price of $4.00 per share. The Company held a subsequent closing of the Offering on February 27, 2020, in which it sold an additional 15,000 shares of common stock at a purchase price of $4.00 per share. The aggregate gross proceeds from the closing of the Offering were $21.5 million (before deducting placement agent fees and expenses of $1.8 million of the closing of the Offering). Offering cost of $177 thousand is included in other assets on the consolidated balance sheets as of December 31, 2019. Yaskawa Letter of Intent In February, 2020, the Company entered into a letter of intent with Yaskawa that the Company believes will form the basis for a mutually beneficial cooperation agreement between the Company and Yaskawa to be finalized later this year. This letter of intent contemplates the following: • Yaskawa intends to enter into a long-term cooperation and development agreement with the Company to use our GaN power device products for a variety of industrial power conversion applications, which will initially focus on servo motor drive applications. • Yaskawa intends to provide at least $4.0 million to fund the Company’s development activities, with an expected funding start date of May 2020, from which amount Yaskawa intends to provide $1.0 million in 2020 in connection with ongoing development activities. Government contract A cost reimbursable subaward (the “Subaward”) grant was made on February 18, 2020 to the Company by Ilinois Institute of Technology (the “IIT”) with Advanced Research Projects Agency - Energy (the “ARPA-E”) funding up to $646 thousand for the development of 1200V Gan switches and which term expires on December 17, 2020. 2020 Equity Incentive Plan The 2020 Equity Incentive Plan (the “2020 Plan”), which provides for the issuance of incentive awards of up to 5,050,000 shares of our common stock, was approved by the board of directors and stockholders in February 2020. The 2020 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, performance units, and performance shares to our employees, directors, and consultants and our parent and subsidiary corporations’ employees and consultants. On March 26, 2020, subject to S-8 filing, the board of directors approved the grant of stock option awards of 1,052,017 shares under the 2020 Plan at an exercise price of $4.00 per share, with a term of ten years, to certain members of management and employees. The stock option awards provide for vesting as follows: 1/3rd after 12 months and 1/36th of the remaining balance monthly or 1/4th after 12 months and 1/48th of the remaining balance monthly. Commitment with A Government Agency In connection with a contract with a government agency, the Company entered into a commitment to acquire equipment and services from vendors totaling $4.9 million, all of which is reimbursable. During February and March 2020, the Company purchased equipment for approximately $3.6 million and was reimbursed in full by the government agency. The remaining commitment under the contract to the vendors is approximately $1.3 million.

Business and Basis of Present_2

Business and Basis of Presentation (Policies)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	The unaudited condensed consolidated financial statements include the accounts of the Parent and its wholly-owned subsidiaries, Transphorm Technology, Transphorm Japan, Inc., Transphorm Japan Epi, Inc. and Transphorm Aizu, Inc. Upon consolidation, all significant intercompany accounts and transactions have been eliminated.	The consolidated financial statements include the accounts of the Transphorm, Inc. and its wholly-owned subsidiaries, Transphorm Japan, Inc., Transphorm Japan Epi, Inc. and Transphorm Aizu, Inc. Upon consolidation, all significant intercompany accounts and transactions have been eliminated.
Use of Estimates	The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates and assumptions on historical experience, knowledge of current conditions, and its belief of what could occur in the future, given available information. Actual results could differ from those estimates, and such differences could be material to the condensed consolidated financial statements. Estimates are used for, but not limited to, the determinations of fair value of stock awards and promissory notes, accrual of liabilities, revenue recognition, inventory reserve, and useful lives for property and equipment.	The preparation of consolidated financial statements in conformity with Accounting Principles Generally Accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates and assumptions on historical experience, knowledge of current conditions, and its belief of what could occur in the future, given available information. Actual results could differ from those estimates, and such differences could be material to the consolidated financial statements. Estimates are used for, but not limited to, the determinations of fair value of stock awards and promissory notes, accrual of liabilities, revenue recognition, inventory reserve, and useful lives for property and equipment.
Reclassification of Prior Year Presentation	Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported condensed consolidated financial statements.	Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported consolidated statements of operations. An adjustment has been made to the consolidated statements of cash flows for the year ended December 31, 2018, to reclass interest expense of $150 thousand to capitalized interest cost. This change in classification does not affect previously reported net cash used in operating activities in the consolidated statements of cash flows.
Cash and Cash Equivalents	The Company considers all highly-liquid investments with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist principally of bank deposits and money market funds.	The Company considers all highly-liquid investments with original maturities of 90 days or less at the date of purchase to be cash equivalents. Cash and cash equivalents consist principally of bank deposits and money market funds.
Foreign Currency Risk	The Company is exposed to foreign currency risk due to its operations in Japan. Assets and liabilities of the operations are re-measured into U.S. currency at exchange rates in effect at the balance sheet dates through the condensed consolidated statements of comprehensive income. Gains or losses resulting from foreign currency transactions are re-measured using the rates on the dates on which those elements are recognized during the period and are included in other income or expense in the unaudited condensed consolidated statements of operations.	The Company is exposed to foreign currency risk due to its operations in Japan. Assets and liabilities of the operations are re-measured into U.S. currency at exchange rates in effect at the balance sheet dates through the consolidated statements of comprehensive income. Gains or losses resulting from foreign currency transactions are re-measured using the rates on the dates on which those elements are recognized during the period and are included in other income or expense in the consolidated statements of operations.
Concentrations of Risk	Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the financial institution holding its cash. The Company’s investment policy restricts investments to high-quality investments and limits the amounts invested with any one issuer, industry or geographic area. Risks associated with cash holdings in excess of insured limits are mitigated by banking with high-quality institutions. To date, the Company has not experienced any significant losses on its cash and cash equivalents. The Company periodically evaluates the relative credit standing of these financial institutions. The Company is subject to risks common in the power conversion components industry, including, but not limited to, technological obsolescence, dependence on key personnel, market acceptance of its products, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed.	Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the financial institution holding its cash. The Company’s investment policy restricts investments to high-quality investments and limits the amounts invested with any one issuer, industry or geographic area. Risks associated with cash holdings in excess of insured limits are mitigated by banking with high-quality institutions. To date, the Company has not experienced any significant losses on its cash and cash equivalents. The Company periodically evaluates the relative credit standing of these financial institutions. The Company is subject to risks common in the power conversion components industry, including, but not limited to, technological obsolescence, dependence on key personnel, market acceptance of its products, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed.
Comprehensive Loss	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes the impact of foreign currency translation adjustments.	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) includes the impact of foreign currency translation adjustments.
Accounts Receivable	Accounts receivable are analyzed and allowances for uncollectible accounts are recorded, as required. Provisions for uncollectible accounts, if any, are recorded as bad debt expense and included in general and administrative expenses in the accompanying unaudited condensed consolidated statements of operations. The process for determining the appropriate level of allowances for doubtful accounts involves judgment, and the Company considers such factors as the age of the underlying receivables, historical and projected collection trends, the composition of outstanding receivables, current economic conditions and regulatory changes. An account is fully reserved when reasonable collection efforts have been unsuccessful and it is probable that the receivable will not be recovered.	Accounts receivable are analyzed and allowances for uncollectible accounts are recorded, as required. Provisions for uncollectible accounts, if any, are recorded as bad debt expense and included in general and administrative expenses in the accompanying consolidated statements of operations. The process for determining the appropriate level of allowances for doubtful accounts involves judgment, and considers such factors as the age of the underlying receivables, historical and projected collection trends, the composition of outstanding receivables, current economic conditions and regulatory changes. An account is fully reserved when reasonable collection efforts have been unsuccessful and it is probable that the receivable will not be recovered.
Inventory	Inventory is stated at the lower of cost (first-in, first-out method) or net realizable value. The Company periodically reviews the value of items in inventory and records write-downs or write-offs based on its assessment of slow moving or obsolete inventory. The Company maintains an inventory reserve for obsolete inventory and generally makes inventory value adjustments against the inventory reserve.	Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value. The Company periodically reviews the value of items in inventory and records write-downs or write-offs based on its assessment of slow moving or obsolete inventory. The Company maintains an inventory reserve for obsolete inventory and generally makes inventory value adjustments against the inventory reserve.
Property and Equipment	Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally ranging from three	Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally ranging from three
Property and Equipment, Impairment	The Company evaluates the carrying amount of its property and equipment whenever events or changes in circumstances indicate that the assets may not be recoverable. An impairment loss would be recognized when estimated future cash flows expected to result from the use of an asset or asset group and its eventual disposition are less than the carrying amount of the asset or asset group.	The Company evaluates the carrying amount of its property and equipment whenever events or changes in circumstances indicate that the assets may not be recoverable. An impairment loss would be recognized when estimated future cash flows expected to result from the use of an asset or asset group and its eventual disposition is less than the carrying amount of the asset or asset group.
Goodwill	Goodwill arose for the acquisition of a business in February 2014 based in Japan and was accounted for as the purchase of a business. Goodwill generated from business combinations and deemed to have indefinite lives are not subject to amortization and instead are tested for impairment at least annually in December unless certain events occur or circumstances change. Goodwill represents the excess of the purchase price over the fair value of the net assets and other identifiable intangible assets acquired. We test for goodwill impairment annually or earlier if events or changes in circumstances indicate goodwill might possibly be impaired. Impairment exists when the carrying value of the goodwill exceeds its implied fair value. An impairment loss would be recognized in an amount equal to that excess as a charge to operations in the unaudited condensed consolidated statements of operations.	Goodwill arose for the acquisition of a business in February 2014 based in Japan and was accounted for as the purchase of a business. Goodwill generated from business combinations and deemed to have indefinite lives are not subject to amortization and instead are tested for impairment at least annually in December unless certain events occur or circumstances change. Goodwill represents the excess of the purchase price over the fair value of the net assets and other identifiable intangible assets acquired. We test for goodwill impairment annually or earlier if events or changes in circumstances indicate goodwill might possibly be impaired. Impairment exists when the carrying value of the goodwill exceeds its implied fair value. An impairment loss would be recognized in an amount equal to that excess as a charge to operations in the consolidated statements of operations.
Intangible Assets	Intangible assets that are not considered to have an indefinite useful life are amortized over their estimated useful lives, which generally range from three	Intangible assets that are not considered to have an indefinite useful life are amortized over their estimated useful lives, which generally range from three
Revenue Recognition	Revenue Recognition Policy The Company derives its revenues from sales of high-powered GaN-based products manufactured utilizing the Company’s proprietary and patented epiwafer technology and wafer fabrication and other assembly processes, sales of GaN epiwafers for the radio frequency (“RF”) and power markets, and sales of licenses to use such patented proprietary technology, as well as enabling EPI wafer growth services and products to our strategic partners. Revenues are recognized when control of these products or licenses are transferred to the Company’s customers in an amount that reflects the consideration it expects to be entitled to in exchange for those products and licenses. Sales and other taxes the Company collects concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense. The Company does not have any significant financing components associated with its revenue contracts, as payment is received at or shortly after the point of sale. Disaggregation of Revenue from Contracts with Customers Revenue consists of licensing revenue, government contract revenue from our contract with the U.S. Navy and product sales, with applicable performance obligations satisfied at a point in time. Products are sold to distributors and end-users in various sectors such as, but not limited to, the automotive, gaming, industrial, IT, and consumer products industries. As part of the Collaboration Arrangement (Note 2 - Nexperia Arrangement) executed with Nexperia on April 4, 2018, the Company agreed to grant Nexperia the perpetual exclusive right to use the Company’s existing Gen-3 manufacturing process technology. License fees are received upon satisfaction of contractual milestones and recognized upon delivery of the perpetual license or transferred technology without any remaining performance obligations. The Company recognized $0 and $5.0 million of licensing revenue for the three and nine months ended September 30, 2020, respectively, and no licensing revenue for each of the three and nine months ended September 30, 2019. Additionally, pursuant to agreements entered into in October 2019, during the three and nine months ended September 30, 2020 and 2019, the Company recognized $280,000 and $0 of revenue from the sale of EPI Gen 4 wafer growths. Government contract revenues are principally generated under research and development contracts. Contract revenues are derived primarily from research contracts with agencies of the U.S. government. We believe credit risk related to accounts receivable arising from such contracts is minimal. These contracts may include cost-plus fixed fee and fixed price terms. All payments to us for work performed on contracts with agencies of the U.S. government are subject to adjustment upon audit by the Defense Contract Audit Agency. The Company received new government authorized rates for billing purposes which allowed for retroactive application since inception. The cumulative impact of this rate change was $505 thousand in the third quarter of 2020. The Company will use the new approved rates on go-forward basis. Performance Obligations For performance obligations related to the sale of products, control transfers to the customer at a point in time. The Company’s principal terms of sale are free on board shipping or destination and the Company transfers control and records revenue for product sales upon shipment or delivery to the customer, respectively. For performance obligations related to the licensing of patented technology in perpetuity, control also transfers to the customer at a point in time. The Company transfers control and records revenue for licensing fees once the Company has (i) provided or otherwise makes available the patented technology to the customer and (ii) the customer is able to use and benefit from the patented technology. Variable Consideration The nature of the Company’s arrangement with Nexperia gives rise to variable consideration in the form of milestone and royalty payments. The royalties qualify for the sales and usage-based royalty exception, as the license of intellectual property is the predominant item to which the royalty relates and are recognized upon the subsequent sale occurring. The variable amounts are received upon satisfaction of contractually agreed upon development targets and sales volume.	Revenue Recognition Policy The Company derives its revenues from sales of high-powered GaN-based products manufactured utilizing their proprietary and patented epiwafer technology and wafer fabrication and other assembly processes, and sales of GaN epiwafers for the RF and power markets, as well as sales of licenses to use such patented proprietary technology. Revenues are recognized when control of these products or licenses are transferred to its customers in an amount that reflects the consideration the Company expects to be entitled to in exchange for those products and licenses. Sales and other taxes the Company collects concurrent with revenue-producing activities are excluded from revenue. Incidental items that are immaterial in the context of the contract are recognized as expense. The Company does not have any significant financing components associated with its revenue contracts, as payment is received at or shortly after the point of sale. Disaggregation of Revenue from Contracts with Customers Revenue for the years ended December 31, 2019 and 2018 consists of licensing revenue, government contract revenue from our contract with the U.S. Navy and product sales, with such performance obligation satisfied at a point in time. Products are sold to distributors and end-users in various sectors such as, but not limited to, the automotive, gaming, industrial, IT, and consumer products industries. As part of the Collaboration Arrangement (Note 3 - Nexperia Arrangement) executed with Nexperia on April 4, 2018, the Company agreed to grant Nexperia the perpetual exclusive right to use the Company’s existing Gen 3 manufacturing process technology. License fees are received upon satisfaction of contractual milestones and recognized upon delivery of the perpetual license or transferred technology without any remaining performance obligations. For the year ended December 31, 2019, the Company received the remaining $6.0 million and recognized a total of $9.0 million, including $3.0 million received in 2018, as licensing revenue upon satisfaction of contractual milestones and delivery of the perpetual license and transferred technology without any remaining performance obligations. For the year ended December 31, 2018, the Company did not recognize any revenue related to the process transfer or technology development performance obligations. The $3.0 million contract liability related to cash received in 2018 from Nexperia is included in deferred revenue. Government contract revenues are principally generated under research and development contracts. Contract revenues are derived primarily from research contracts with agencies of the United States Government. We believe credit risk related to accounts receivable arising from such contracts is minimal. These contracts may include cost-plus fixed fee and fixed price terms. All payments to us for work performed on contracts with agencies of the U.S. Government are subject to adjustment upon audit by the Defense Contract Audit Agency. Performance Obligations For performance obligations related to the sale of products, control transfers to the customer at a point in time. The Company’s principal terms of sale are free on board shipping or destination and the Company transfers control and records revenue for product sales upon shipment or delivery to the customer, respectively. For performance obligations related to the licensing for the use of patented technology in perpetuity, control also transfers to the customer at a point in time. The Company transfers control and records revenue for licensing fees once the Company has (i) provided or otherwise makes available the patented technology to the customer and (ii) the customer is able to use and benefit from the patented technology. Variable Consideration The nature of the Company’s arrangement with Nexperia gives rise to variable consideration in the form of milestone and royalty payments. The royalties qualify for the sales and usage-based royalty exception, as the license of intellectual property is the predominant item to which the royalty relates and are recognized upon the subsequent sale occurring. The variable amounts are received upon satisfaction of contractually agreed upon development targets and sales volume.
Research and Development	The Company is a party to research grant contracts with the U.S. government for which the Company is reimbursed for specified costs incurred for its research projects. These projects include energy saving initiatives for which the U.S. government offers reimbursement funds. Such reimbursements are recorded as an offset to research and development expenses when the related qualified research and development expenses are incurred. Reimbursable costs are recognized in the same period the costs are incurred up to the limit of approved funding amounts on qualified expenses.	The Company is a party to research grant contracts with the U.S. federal government for which the Company is reimbursed for specified costs incurred for its research projects. These projects include energy saving initiatives for which the U.S. federal government offers reimbursement funds. Such reimbursements are recorded as an offset to research and development expenses when the related qualified research and development expenses are incurred. Reimbursable costs are recognized in the same period the costs are incurred up to the limit of approved funding amounts on qualified expenses.
Stock-Based Compensation	All share-based payments, including grants of stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”), are measured at the fair value of the share-based awards on the grant date and recognized over their respective vesting periods, which is generally one The Black-Scholes-Merton option pricing model requires inputs such as the fair value of common stock on date of grant, expected term, expected volatility, dividend yield, and risk-free interest rate. Further, the forfeiture rate also affects the amount of aggregate compensation expense. These inputs are subjective and generally require significant analysis and judgment to develop. Volatility data is obtained from a study of publicly traded industry peer companies. The forfeiture rate is derived primarily from the Company’s historical data, and the risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues commensurate with the expected term. Management generally uses the simplified method to calculate the expected term for employee grants as the Company has limited historical exercise data or alternative information to reasonably estimate an expected term assumption. The simplified method assumes that all options will be exercised midway between the weighted average vesting date and the contractual term of the option. Stock-based compensation expense recognized in the Company’s condensed consolidated financial statements is based on awards that are expected to vest. These expense amounts have been reduced by using an estimated forfeiture rate. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company evaluates the assumptions used to estimate forfeitures annually in connection with the recognition of stock-based compensation expense.	All share-based payments, including grants of stock options, are measured based on the fair value of the share-based awards at the grant date and recognized over their respective vesting periods, which is generally four years. The estimated fair value of stock options at the grant date is determined using the Black-Scholes-Merton pricing model. The Company recognizes the fair value of share-based payments as compensation expense for all expected-to-vest stock-based awards over the vesting period of the award using the straight-line attribution method provided that the amount of compensation cost recognized at any date is no less than the portion of the grant-date fair value of the award that is vested at that date. The Black-Scholes-Merton option pricing model requires inputs such as the fair value of common stock on date of grant, expected term, expected volatility, dividend yield, and risk-free interest rate. Further, the forfeiture rate also affects the amount of aggregate compensation expense. These inputs are subjective and generally require significant analysis and judgment to develop. Volatility data is obtained from a study of publicly traded industry peer companies. The forfeiture rate is derived primarily from the Company’s historical data, and the risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues commensurate with the expected term. Management generally uses the simplified method to calculate the expected term for employee grants as the Company has limited historical exercise data or alternative information to reasonably estimate an expected term assumption. The simplified method assumes that all options will be exercised midway between the weighted average vesting date and the contractual term of the option. Stock-based compensation expense recognized in the Company’s consolidated financial statements is based on awards that are expected to vest. These expense amounts have been reduced by using an estimated forfeiture rate. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The Company evaluates the assumptions used to estimate forfeitures annually in connection of recognition of stock-based compensation expense.
Loss Per Share	Basic loss per share is calculated by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted loss per share is calculated by dividing the net loss attributable to common stockholders by the sum of the weighted average number of common shares outstanding plus potential dilutive common shares outstanding during the period. Potential dilutive securities, comprised of stock warrants, restricted stock units and stock options, are not reflected in diluted loss per share because such shares are anti–dilutive. Dilutive impact of potential common shares resulting from common stock equivalents is determined by applying the treasury stock method.	Basic loss per share is calculated by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated by dividing the net income attributable to common stockholders by the sum of the weighted average number of common shares outstanding plus potential dilutive common shares outstanding during the period. Potential dilutive securities, comprised of the convertible preferred stock, stock warrants and stock options, are not reflected in diluted net loss per share because such shares are anti–dilutive. Dilutive impact of potential common shares resulting from common stock equivalents is determined by applying the treasury stock method.
Fair Value Measurement	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying values of the Company’s financial instruments such as cash equivalents, accounts receivable, revolving credit facility, accounts payable and accrued liabilities approximate fair values due to the short-term nature of these items. The Company has elected the fair value option for its promissory notes.	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The carrying values of the Company’s financial instruments such as cash equivalents, accounts receivable, revolving credit facility, accounts payable and accrued liabilities approximate fair values due to the short-term nature of these items. The Company has elected the fair value option for its promissory notes. See Note 4 - Fair Value Measurements for more information.
Income Taxes	The Company accounts for income taxes in accordance with Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”). ASC 740 prescribes the use of the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement carrying amounts and the tax basis of assets and liabilities and are measured using the enacted statutory tax rates in effect at the balance sheet date. The Company records a valuation allowance to reduce its deferred tax assets when uncertainty regarding their realizability exists.	The Company accounts for income taxes in accordance with Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”). ASC 740 prescribes the use of the liability method. Deferred tax assets and liabilities are determined based on the difference between the financial statement carrying amounts and the tax basis of assets and liabilities and are measured using the enacted statutory tax rates in effect at the balance sheet date. The Company records a valuation allowance to reduce its deferred tax assets when uncertainty regarding their realizability exists.
Equity Method Investments	The Company uses the equity method to account for investments in entities that it does not control, but in which it has the ability to exercise significant influence over operating and financial policies. The Company's proportionate share of the net income or loss of these companies is included in consolidated net loss. Judgments regarding the level of influence over each equity method investment include consideration of key factors such as the Company's ownership interest, representation on the board of directors or other management body and participation in policy-making decisions.	The Company uses the equity method to account for investments in entities that it does not control, but in which it has the ability to exercise significant influence over operating and financial policies. The Company's proportionate share of the net income or loss of these companies is included in consolidated net earnings. Judgments regarding the level of influence over each equity method investment include consideration of key factors such as the Company's ownership interest, representation on the board of directors or other management body and participation in policy-making decisions.
Segment Reporting	The Company’s operations and its financial performance is evaluated on a consolidated basis by the chief operating decision maker. Accordingly, the Company considers all of its operations to be aggregated in one reportable operating segment.	The Company’s operations and its financial performance is evaluated on a consolidated basis by the chief operating decision maker. Accordingly, the Company considers all of its operations to be aggregated in one reportable operating segment.
Recently Issued Accounting Standards Adopted and under Evaluation	Fair Value - In August 2018, the Financial Accounting Standard Boards (“FASB”) issued Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 removes certain disclosures, modifies certain disclosures and adds additional disclosures. ASU 2018-13 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. The Company adopted this standard effective January 1, 2020. The adoption of ASU 2018-13 did not have a material effect on the condensed consolidated financial statements. Statement of Cash Flows - In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows : Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). This guidance addresses eight specific cash flow issues with the objective of reducing existing diversity in practice. ASU 2016-15 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. The Company adopted this standard effective January 1, 2020, using the modified retrospective approach. The adoption of ASU 2016-15 did not have a material effect on the condensed consolidated financial statements. Recently Issued Accounting Standards under Evaluation Leases - In June 2020, the FASB issued ASU 2020-05, which amends the effective dates of the FASB’s standards on leasing (ASC 842) to give immediate relief to certain entities as a result of the widespread adverse economic effects and business disruptions caused by the COVID-19 pandemic. In February 2016, the FASB issued ASU 2016-02, Leases , which, for operating leases, requires the lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, on its balance sheet. The guidance also requires a lessee to recognize single lease costs, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. The leasing standard’s effective dates were the fiscal year beginning after December 15, 2019 as originally issued (ASU 2016-02) and the fiscal year beginning after December 15, 2020 as amended by ASU 2019-10. As amended by ASU 2020-05, the leasing standard’s effective date is now the fiscal year beginning after December 15, 2021. The Company is currently evaluating the impact of this new standard on its condensed consolidated financial statements. Financial Instruments - FASB ASU 2020-03, Codification Improvements to Financial Instruments , makes clear the determination of the contractual life of a net investment in leases in estimating expected credit losses under ASC 326, Financial Instruments – Credit Losses. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). The standard changes the methodology for measuring credit losses on financial instruments and the timing of when such losses are recorded. ASU 2016-13 is effective for the Company’s 2021 fiscal year. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its condensed consolidated financial statements. Income Tax - In December 2019, the FASB issued ASU 2019-12, which modifies ASC 740 to simplify the accounting for income taxes. The ASU’s amendments are based on changes that were suggested by stakeholders as part of the FASB’s simplification initiative (i.e., the FASB’s effort to reduce the complexity of accounting standards while maintaining or enhancing the helpfulness of information provided to financial statement users). ASU 2019-12 is effective for the Company’s 2021 fiscal year. The Company is currently evaluating the impact of this new standard on its condensed consolidated financial statements.	In July 2017, the Financial Accounting Standards Boards (“FASB”) issued Accounting Standards Update (“ASU”) 2017-11, Earnings Per Shares (Topic 260), Distinguishing Liabilities from Equity (Topic 480) and Derivatives and Hedging (Topic 815). ASU 2017-11 changes the classification analysis of certain equity-linked financial instruments, such as warrants and embedded conversion features, such that a down round feature is disregarded when assessing whether the instrument is indexed to an entity’s own stock under Subtopic 815-40. As a result, a down round feature no longer requires an instrument to be remeasured at fair value through earnings each period, although all other aspects of the indexation guidance under Subtopic 815-40 continue to apply. ASU 2017-11 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company adopted this standard, which did not have a material effect on the consolidated financial statements. Stock Compensation - In May 2017, the FASB issued ASU 2017-09, Compensation -Stock Compensation (Topic 718) (“ASU 2017-09”), which clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. ASU 2017-09 is effective for the Company’s 2018 fiscal year, although early adoption is permitted. The Company adopted this standard, which did not have a material effect on the consolidated financial statement. Recently Issued Accounting Standards under Evaluation Income Tax - In December 2019, the FASB issued ASU 2019-12, which modifies ASC 740 to simplify the accounting for income taxes. The ASU’s amendments are based on changes that were suggested by stakeholders as part of the FASB’s simplification initiative (i.e., the Board’s effort to reduce the complexity of accounting standards while maintaining or enhancing the helpfulness of information provided to financial statement users). ASU 2019-12 is effective for the Company’s 2021 fiscal year. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Fair Value - In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (ASC 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement. ASU 2018-13 removes certain disclosures, modifies certain disclosures and adds additional disclosures. ASU 2018-13 is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Statement of Cash Flows - In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). This guidance addresses eight specific cash flow issues with the objective of reducing existing diversity in practice. ASU 2016-15 is effective for the Company's 2020 fiscal year. The guidance is to be adopted retrospectively unless impracticable upon which the guidance is to be adopted prospectively. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Financial Instruments - In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). The standard changes the methodology for measuring credit losses on financial instruments and the timing of when such losses are recorded. ASU 2016-13 is effective for the Company’s 2021 fiscal year. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements. Leases - In February 2016, the FASB issued ASU 2016-02, Leases , which, for operating leases, requires the lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, on its balance sheet. The guidance also requires a lessee to recognize single lease costs, calculated so that the cost of the lease is allocated over the lease term, on a generally straight-line basis. This guidance will be effective for the Company in fiscal year 2021 and must be adopted using a modified retrospective transition approach. Early adoption is permitted. The Company is currently evaluating the impact of this new standard on its consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Liabilities measured at fair value by level	The following table summarizes the Company’s liabilities measured at fair value as of September 30, 2020 and December 31, 2019, by level within the fair value hierarchy (in thousands) : Level 1 Level 2 Level 3 September 30, 2020 Promissory note $ — $ — $ 16,327 December 31, 2019 Promissory note $ — $ — $ 16,169	The following table summarizes the Company’s liabilities measured at fair value as of December 31, 2019 and 2018, by level within the fair value hierarchy ( in thousands ): Level 1 Level 2 Level 3 December 31, 2019 Promissory note $ — $ — $ 16,169 December 31, 2018 Promissory note $ — $ — $ 15,852
Changes in fair value of promissory notes	The following table includes the changes in fair value of the promissory note which are Level 3 on the fair value hierarchy (in thousands) : 2020 Fair value at January 1, $ 16,169 Interest expense accrued 112 Increase in fair value 46 Fair value at September 30, $ 16,327 2019 Fair value at January 1, $ 15,852 Interest expense accrued 150 Increase in fair value 167 Fair value at December 31, $ 16,169	The following table includes the changes in fair value of the promissory notes which are Level 3 on the fair value hierarchy ( in thousands ): 2019 2018 Fair value at January 1, $ 15,852 $ 27,756 Interest expense accrued 150 364 Principal and interest expense paid — (13,328) Increase in fair value 167 1,060 Fair value at December 31, $ 16,169 $ 15,852

Concentration of Credit Risk _2

Concentration of Credit Risk and Significant Customers (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Risks and Uncertainties [Abstract]
Schedules of concentration of risk, by risk factor	Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following table: Revenue for the Nine Months Ended September 30, Accounts Receivable As of 2020 2019 September 30, 2020 December 31, 2019 Customer A 67.3% 14.6% 44.0% 60.0% Customer B 26.0% 51.1% 36.1% 20.4%	Significant customers are those that represent 10% or more of revenue or accounts receivable and are set forth in the following: Revenue for the Year Ended December 31, Accounts Receivable As of December 31, 2019 2018 2019 2018 Customer A * 44.0% * 22.7% Customer B * 17.6% * 43.7% Customer C * 16.0% * * Customer D 79.6% * 60.0% 19.3% Customer E 13.3% * 20.4% * * Less than 10% of total

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of inventory	Inventory consists of the following as of December 31, 2019 and 2018 ( in thousands ): As of December 31, 2019 2018 Raw materials $ 412 $ 258 Work in process 258 270 Finished goods 320 324 Total $ 990 $ 852

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property and equipment as of December 31, 2019 and 2018 consists of the following ( in thousands except years ): As of December 31, Estimated Useful Life 2019 2018 Machinery and equipment $ 14,892 $ 14,551 5 Computer equipment and software 876 787 3 Furniture and fixtures 186 185 7 Leasehold improvements (1) 4,954 4,952 7 Construction in progress 6 263 Property and equipment 20,914 20,738 Less: accumulated depreciation and amortization (19,144) (18,606) Property and equipment, net $ 1,770 $ 2,132 (1) Leasehold improvements are amortized on a straight-line basis over the shorter of their estimated useful lives or the related remaining lease term.

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The carrying values of intangible assets as of December 31, 2019 and 2018, respectively, consists of the following ( in thousands except years ): December 31, 2019 Gross Accumulated Amortization Foreign Exchange Rate Changes Net Estimated Useful Life Patents $ 2,963 $ (1,679) $ — $ 1,284 10 Developed technology - 150V 560 (519) (34) 7 6 Developed technology - 600V 1,701 (1,575) (104) 22 6 Total $ 5,224 $ (3,773) $ (138) $ 1,313 December 31, 2018 Gross Accumulated Amortization Foreign Exchange Rate Changes Net Estimated Useful Life Patents $ 2,963 $ (1,383) $ — $ 1,580 10 Developed technology - 150V 560 (425) (41) 94 6 Developed technology - 600V 1,701 (1,291) (126) 284 6 Total $ 5,224 $ (3,099) $ (167) $ 1,958
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Estimated future amortization expenses related to intangible assets at December 31, 2019 are as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 325 2021 296 2022 296 2023 296 Thereafter 100 Total $ 1,313

Debts (Tables)

Debts (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of promissory note obligation	The Company’s promissory note obligation at September 30, 2020 and December 31, 2019 consists of the following (in thousands) : Stated Value at Interest Rate Due Date September 30, 2020 December 31, 2019 Yaskawa Note 1.00% September 2022 $ 15,448 $ 15,336	The Company’s promissory note obligation at December 31, 2019 and 2018 consists of the following ( in thousands ): Stated Value at December 31, Interest Rate Due Date 2019 2018 Yaskawa Note 1.00% September 2022 $ 15,336 $ 15,186
Schedule of fair value option	As of September 30, 2020 and December 31, 2019, the Company determined the fair value for the note, as compared to the face value, including accrued interest, as follows (in thousands) : Fair Value at September 30, 2020 December 31, 2019 Yaskawa Note $ 16,327 $ 16,169	Pursuant to ASC 825-10-15-4, the Company elected to apply the fair value option for the promissory note. As of December 31, 2019 and 2018, the Company determined the fair value for the note, as compared to the face value, including accrued interest, as follows ( in thousands ): Fair Value at December 31, 2019 2018 Yaskawa Note $ 16,169 $ 15,852
Schedule of maturities of long-term debt	As of September 30, 2020, the scheduled maturity on the development loans, revolving credit facility and promissory note was as follows (in thousands) : Year Ending December 31, Amount 2020 $ 10,153 2021 10,000 2022 15,748 Total $ 35,901	As of December 31, 2019, the scheduled maturity on the development loans, revolving credit facility and promissory note was as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 15,458 2021 10,000 2022 15,748 Total $ 41,206

Investment in Aizu Fujitsu Se_2

Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited ("AFSW") (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities	The Company’s investment activities in AFSW for the nine months ended September 30, 2020 and the year ended December 31, 2019 are summarized below (in thousands) : For the Nine Months Ended September 30, 2020 For the Year Ended December 31, 2019 Beginning balance $ (1,688) $ (659) Investment 5,327 2,698 Loss (5,218) (3,703) Effect of exchange rate change (105) (24) Ending balance $ (1,684) $ (1,688) Summarized financial information (unaudited) of AFSW for the periods indicated, as provided by the controlling owner, are as follows (in thousands) : As of September 30, 2020 December 31, 2019 Current assets $ 1,138 $ 3,733 Long-term assets $ 5,412 $ 5,101 Other current liabilities $ 2,557 $ 931 Due to controlling owner $ 19,633 $ 17,913 Due to Transphorm $ 10,910 $ 5,349 Net deficit $ (26,550) $ (15,359) Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Sales $ 492 $ 2,613 $ 2,278 $ 8,864 Gross loss $ (3,170) $ (835) $ (8,515) $ (4,002) Net loss $ (3,965) $ (1,585) $ (10,649) $ (6,130)	The Company’ investment activities in AFSW for the years ended December 31, 2019 and 2018 are summarized below ( in thousands ): 2019 2018 Beginning balance at January 1, $ (659) $ (98) Investment 2,698 1,852 Loss (3,703) (2,404) Effect of exchange rate change (24) (9) Ending balance at December 31, $ (1,688) $ (659) Summarized financial information of AFSW as of December 31, 2019 and 2018 and are as follows ( in thousands ) as provided by the controlling owner: As of December 31, 2019 2018 Current assets $ 3,733 $ 4,096 Long-term assets $ 5,101 $ 4,194 Other current liabilities $ 931 $ 961 Due to controlling owner $ 17,913 $ 12,031 Due to Transphorm $ 5,349 $ 2,960 Net deficit $ (15,359) $ (7,662) Year Ended December 31, 2019 2018 Sales $ 11,599 $ 22,283 Gross loss $ (4,849) $ (2,523) Net loss $ (7,557) $ (4,906)

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum operating lease commitments	As of September 30, 2020, future minimum operating lease commitments were as follows (in thousands) : Year Ending December 31, Amount 2020 $ 180 2021 571 2022 163 Total $ 914	As of December 31, 2019, future minimum operating lease commitments were as follows ( in thousands ): Year Ending December 31, Amount 2020 $ 705 2021 489 2022 163 Total $ 1,357

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Schedule of convertible preferred stock by class	At September 30, 2020, the Company has reserved shares of common stock for future issuance as follows: Equity incentive plans 5,042,525 Common stock warrants 15,461 Total 5,057,986	As of December 31, 2019 and 2018, the Company’s convertible preferred stock consists of the following ( in thousands, except share and per share data on a post conversion basis ): Authorized Shares Outstanding Shares Carrying Value Par Value per Share Preference Value Series 1 12,438,704 12,433,953 $ 39,658 $ 0.001 $ 40,000 Series 2 7,507,699 7,499,996 30,000 $ 0.001 30,000 Series 3 4,000,000 4,000,000 16,000 $ 0.001 16,000 Total 23,946,403 23,933,949 $ 85,658 $ 86,000 At December 31, 2019, the Company has reserved shares of common stock for future issuance as follows: Conversion of convertible preferred stock 23,946,403 Stock option plans 4,023,826 Common stock warrants 15,461 Total 27,985,690

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Schedule of convertible preferred stock by class	At September 30, 2020, the Company has reserved shares of common stock for future issuance as follows: Equity incentive plans 5,042,525 Common stock warrants 15,461 Total 5,057,986	As of December 31, 2019 and 2018, the Company’s convertible preferred stock consists of the following ( in thousands, except share and per share data on a post conversion basis ): Authorized Shares Outstanding Shares Carrying Value Par Value per Share Preference Value Series 1 12,438,704 12,433,953 $ 39,658 $ 0.001 $ 40,000 Series 2 7,507,699 7,499,996 30,000 $ 0.001 30,000 Series 3 4,000,000 4,000,000 16,000 $ 0.001 16,000 Total 23,946,403 23,933,949 $ 85,658 $ 86,000 At December 31, 2019, the Company has reserved shares of common stock for future issuance as follows: Conversion of convertible preferred stock 23,946,403 Stock option plans 4,023,826 Common stock warrants 15,461 Total 27,985,690
Schedule of stockholders' equity note, warrants or rights	At September 30, 2020, the following warrants to purchase common stock were outstanding: Number of Shares Exercise Price Expiration Date 6,046 $34.74 November 2020 6,046 $34.74 5 years after an initial public offering of the Company 3,369 $54.41 5 years after an initial public offering of the Company 15,461	At December 31, 2019, the following warrants to purchase common stock were outstanding: Number of Shares Exercise Price Expiration Date 6,046 $34.74 November 2020 6,046 $34.74 5 years after an initial public offering of the Company 3,369 $54.41 5 years after an initial public offering of the Company 15,461

Stock Option Plans (Tables)

Stock Option Plans (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of stock option activity	The following table summarizes stock option activity and related information for the three months ended September 30, 2020 and 2019: Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value (1) (in thousands) Balance at July 1, 2020 2,454,687 $ 4.74 6.33 $ — Options exercised (3,475) $ 3.80 Options canceled (123,789) $ 5.91 Balance at September 30, 2020 2,327,423 $ 4.68 6.16 $ 167 Exercisable at September 30, 2020 2,211,723 $ 4.74 6.08 $ 111 Balance at July 1, 2019 2,342,440 $ 4.84 7.16 $ — Options granted 125,183 $ 3.14 Options canceled (13,811) $ 4.58 Balance at September 30, 2019 2,453,812 $ 4.69 7.06 $ — Exercisable at September 30, 2019 1,984,257 $ 4.95 6.85 $ — (1) Intrinsic value represents the excess of the fair value on the last trading day of the period, which was $4.00 as of September 30, 2020, over the exercise price, multiplied by the number of options. The following table summarizes stock option activity and related information for the nine months ended September 30, 2020 and 2019: Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (1) (in thousands) Balance at January 1, 2020 2,473,130 $ 4.67 6.84 $ — Options authorized — $ — Options exercised (6,821) $ 3.78 Options canceled (138,886) $ 5.72 Balance at September 30, 2020 2,327,423 $ 4.68 6.16 $ 167 Exercisable at September 30, 2020 2,211,723 $ 4.74 6.08 $ 111 Balance at January 1, 2019 2,377,180 $ 4.83 7.46 $ — Options granted 183,109 $ 3.14 Options canceled (106,477) $ 4.34 Balance at September 30, 2019 2,453,812 $ 4.69 7.06 $ — Exercisable at September 30, 2019 1,984,257 $ 4.95 6.85 $ — (1) Intrinsic value represents the excess of the fair value on the last trading day of the period, which was $4.00 as of September 30, 2020, over the exercise price, multiplied by the number of options.	The following table summarizes stock option activity under the 2007 Plan and 2015 Plan and related information: Number of Shares Available for Grant Number of Options Outstanding Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (in Years) Aggregate Intrinsic Value Balance at January 1, 2018 1,589,381 2,435,837 $ 4.80 8.38 $ — Options granted (46,005) 46,005 $ 4.34 Options canceled 104,662 (104,662) $ 4.70 Balance at December 31, 2018 1,648,038 2,377,180 $ 4.79 7.46 $ — Options granted (209,908) 209,908 $ 3.14 Options exercised — (1,392) $ 3.86 Options canceled 112,498 (112,498) $ 4.34 Balance at December 31, 2019 1,550,628 2,473,198 $ 4.67 6.84 $ — Exercisable at December 31, 2019 2,079,809 $ 4.95 6.65 $ —
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions		The assumptions used to value options granted to employees during the year ended December 31, 2019 and 2018, were as follows: Year Ended December 31, 2019 2018 Weighted average expected life (in years) 5.46 5.84 Risk-free interest rate 1.34% - 1.94% 2.51% - 2.52% Expected volatility 39.4% - 39.8% 38.1% - 38.2% Weighted average grant date fair value $1.04 $0.84 Dividend yield —% —%
Schedule of unvested restricted stock units	The following table summarizes RSA activity and related information for the three and nine months ended September 30, 2020: September 30, 2020 Three Months Ended Nine Months Ended Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Balance at beginning of period — $ — — $ — Granted 123,501 $ 4.00 123,501 $ 4.00 Vested (86,450) $ 4.00 (86,450) $ 4.00 Balance at end of period 37,051 $ 4.00 37,051 $ 4.00 September 30, 2020 Three Months Ended Nine Months Ended Number of Shares Weighted-Average Grant Date Fair Value Per Share Number of Shares Weighted-Average Grant Date Fair Value Per Share Balance at beginning of period — $ — — $ — Granted 816,180 $ 4.00 816,180 $ 4.00 Vested (4,000) $ 4.00 (4,000) $ 4.00 Balance at end of period 812,180 $ 4.00 812,180 $ 4.00
Stock-based compensation expense	The accompanying condensed consolidated statement of operations and comprehensive loss includes stock-based compensation expense as follows (in thousands) : Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Cost of revenue $ 17 $ 24 $ 43 $ 44 Research and development 62 60 148 146 Sales and marketing 11 8 23 24 General and administrative 494 67 606 221 Total $ 584 $ 159 $ 820 $ 435	The accompanying consolidated statement of operations includes stock-based compensation expense as follows ( in thousands ): Year Ended December 31, 2019 2018 Cost of revenue $ 60 $ 41 Research and development 196 186 Sales and marketing 30 45 General and administrative 280 313 Total $ 566 $ 585
Unrecognized stock based compensation	Unrecognized stock-based compensation expense was as follows (in thousands) : As of September 30, 2020 As of September 30, 2019 Unrecognized Expense Average Expected Recognition Period Unrecognized Expense Average Expected Recognition Period Stock options $ 113 0.87 years $ 573 1.34 years Restricted stock $ 3,297 2.64 years — — Total $ 3,410 2.43 years $ 573 1.34 years

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities		Significant components of the Company’s deferred tax assets and deferred tax liabilities are as follows ( in thousands ): As of December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 43,973 $ 42,181 Tax credits 4,535 3,808 California capitalized research and development 343 290 Depreciation — 153 Others, net 602 318 Total deferred tax assets 49,453 46,750 Valuation allowance (49,403) (46,749) Deferred tax asset, net of valuation allowance 50 1 Deferred tax liabilities: Others, net — (1) Fixed assets (50) — Total deferred tax liabilities (50) (1) Net deferred tax assets $ — $ —
Schedule of Effective Income Tax Rate Reconciliation	Reconciliation between federal statutory tax rate and the effective tax rate is shown in the following table: Year Ended December 31, 2019 2018 Federal statutory income tax rate 21.00% 21.00% Research and development credit 4.76% 1.61% Nondeductible expenses (3.18)% (1.81)% Loss in joint venture (7.44)% (1.99)% Foreign income tax rate difference 2.99% (1.04)% Others, net (0.78)% 0.02% Valuation allowance (17.35)% (17.79)% Effective tax rate —% —%

Business and Basis of Present_3

Business and Basis of Presentation (Details)	Feb. 12, 2020shares$ / shares	Feb. 29, 2020USD ($)	Sep. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)Rateshares	Sep. 30, 2019USD ($)shares	Sep. 30, 2020USD ($)segmentshares	Sep. 30, 2019USD ($)shares	Dec. 31, 2019USD ($)segmentRateshares	Dec. 31, 2018USD ($)shares	Jun. 30, 2020shares	Feb. 11, 2020shares	Jun. 30, 2019shares	Mar. 26, 2018shares	Feb. 28, 2018shares	Dec. 31, 2017shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)				31,850,304				31,850,304
Convertible preferred stock, shares issued (in shares)				31,850,304				31,850,304	31,850,304
Convertible preferred stock, shares outstanding (in shares)				31,850,304				31,850,304
Common stock, shares authorized (in shares)			750,000,000	29,012,034		750,000,000		29,012,034	29,012,034					24,867,458
Common stock, shares issued (in shares)	4,171,571		35,266,496	4,220,998		35,266,496		4,220,998	4,219,606		50,325,662
Common stock outstanding (in shares)	4,171,571		35,266,496	4,220,998		35,266,496		4,220,998	4,219,606		50,325,662
Conversion rate for options and warrants | Rate				1206.3959%				1206.3959%
Merger conversion rate (in shares)	0.08289152527
Common stock, forfeited and cancelled (in shares)	682,699
Shares issued under company plans (in shares)	2,461,923		2,327,423	2,473,130	2,453,812	2,327,423	2,453,812	2,473,130	2,377,180	2,454,687		2,342,440			2,435,837
Number of shares (in shares)	15,461		15,461	15,461		15,461		15,461			186,535
Conversion price per share on convertible note payable (in dollars per share) | $ / shares	$ 5.12
Maximum number of shares of common stock issuable (in shares)	3,076,171
Proceeds from Issuance of Common Stock | $		$ 19,700,000				$ 19,741,000	$ 0
Goodwill impairment charges | $			$ 0	$ 0		0	0	$ 0	$ 0
Impairment of intangible assets | $			0		$ 0	0	0
Grant reimbursement | $			$ 81,000		$ 0	$ 380,000	$ 0
Number of anti-dilutive shares (in shares)			3,155,064		2,469,273	3,155,064	2,469,273	26,422,608	26,337,286
Number of reportable segments | segment						1		1
Revenue, net | $			$ 1,929,000		$ 994,000	$ 9,358,000	$ 2,011,000	$ 11,934,000	$ 1,358,000
Cash and cash equivalents | $			4,369,000	2,875,000		4,369,000		2,875,000	$ 3,069,000
Accounts Receivable, Allowance for Credit Loss | $			0	$ 0		0		0
Revenue From Contract With Customer, Cumulative Impact Of Rate Change | $			505,000
Common Stockholder
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Products sold to related party | $					178,000		293,000
EPI Gen 4 Wafer Growth Sales [Member] | Common Stockholder
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Products sold to related party | $			280,000		0	280,000	$ 0
License and Service [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Revenue, net | $			$ 0		$ 0	$ 5,000,000		$ 0
Series 1 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)			0	12,438,704		0		12,438,704	12,438,704
Convertible preferred stock, shares issued (in shares)			0	12,433,953		0		12,433,953	12,433,953		51,680,254
Convertible preferred stock, shares outstanding (in shares)			0	12,433,953		0		12,433,953	12,433,953		51,680,254
Common stock, shares issued (in shares)	12,433,953
Common stock outstanding (in shares)	12,433,953
Series 2 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)			0	7,507,699		0		7,507,699	7,507,699
Convertible preferred stock, shares issued (in shares)			0	7,499,996		0		7,499,996	7,499,996		38,760,190
Convertible preferred stock, shares outstanding (in shares)			0	7,499,996		0		7,499,996	7,499,996		38,760,190
Common stock, shares issued (in shares)	7,499,996
Common stock outstanding (in shares)	7,499,996
Series 3 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)			0	4,000,000		0		4,000,000	4,000,000
Convertible preferred stock, shares issued (in shares)			0	4,000,000		0		4,000,000	4,000,000		31,850,304		4,000,000
Convertible preferred stock, shares outstanding (in shares)			0	4,000,000		0		4,000,000	4,000,000		31,850,304
Common stock, shares issued (in shares)	4,000,000
Common stock outstanding (in shares)	4,000,000
Previously Reported
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Common stock, shares authorized (in shares)				350,000,000				350,000,000	350,000,000
Common stock, shares issued (in shares)				50,921,951				50,921,951	50,905,160
Common stock outstanding (in shares)				50,921,951				50,921,951	50,905,160
Shares issued under company plans (in shares)				2,473,198				2,473,198
Previously Reported | Series 1 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)				51,700,000				51,700,000	51,700,000
Convertible preferred stock, shares issued (in shares)				51,680,254				51,680,254	51,680,254
Convertible preferred stock, shares outstanding (in shares)				51,680,254				51,680,254	51,680,254
Previously Reported | Series 2 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)				38,800,000				38,800,000	38,800,000
Convertible preferred stock, shares issued (in shares)				38,760,190				38,760,190	38,760,190
Convertible preferred stock, shares outstanding (in shares)				38,760,190				38,760,190	38,760,190
Previously Reported | Series 3 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, authorized (in shares)									31,850,304
Convertible preferred stock, shares outstanding (in shares)									31,850,304
Stock options
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of anti-dilutive shares (in shares)			2,327,423		2,453,812	2,327,423	2,453,812	2,473,198	2,377,180
Warrant
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of anti-dilutive shares (in shares)			15,461		15,461	15,461	15,461	15,461	26,157
Restricted Stock [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of anti-dilutive shares (in shares)			812,180			812,180
Minimum
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property and equipment, estimated useful life						3 years		3 years
Estimated useful life (in years)						3 years		3 years
Award vesting period						1 year
Maximum
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property and equipment, estimated useful life						7 years			7 years
Estimated useful life (in years)						10 years		10 years
Award vesting period						4 years
JAPAN
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of cash and cash equivalents in foreign subsidiary			0.90%	1.90%		0.90%		1.90%	8.60%
Revenue, net | $			$ 289,000		$ 6,000	$ 321,000	$ 25,000	$ 28,000	$ 49,000
Cash and cash equivalents | $			41,000	$ 55,000		41,000		55,000	264,000
UNITED STATES
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Revenue, net | $			1,600,000		$ 988,000	9,000,000	$ 2,000,000	11,900,000	1,300,000
Other Assets
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Cash included in other assets | $			75,000	75,000		75,000		75,000	75,000
Yaskawa Note
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Maximum number of shares of common stock issuable (in shares)	3,076,171
Accrued interest on promissory note | $			448,000	$ 336,000		448,000		$ 336,000	$ 186,000
Long-term Debt, Excluding Current Maturities | $			$ 15,000,000			$ 15,000,000
Transphorm Technology 2007 Stock Plan and 2015 Equity Incentive Plan
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Shares issued under company plans (in shares)	29,703,285
Series 1 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, shares issued (in shares)	51,680,254
Convertible preferred stock, shares outstanding (in shares)	51,680,254
Share conversion in connection with the Merger (in shares)	12,433,953
Series 2 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, shares issued (in shares)	38,760,190
Convertible preferred stock, shares outstanding (in shares)	38,760,190
Conversion of stock (in shares)	7,499,996
Series 3 Preferred Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Convertible preferred stock, shares issued (in shares)	31,850,304
Convertible preferred stock, shares outstanding (in shares)	31,850,304
Conversion of stock (in shares)	4,000,000
Common Stock
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Common stock outstanding (in shares)			35,266,496	4,220,998	4,219,606	35,266,496	4,219,606	4,220,998	4,219,606	35,135,520		4,219,606			4,219,606
Price per share (in dollars per share) | $ / shares	$ 4
Share conversion in connection with the Merger (in shares)						23,933,949
Transphorm Technology
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Share conversion in connection with the Merger (in shares)	28,105,520

Accounting Policies (Details)

Accounting Policies (Details)	3 Months Ended			9 Months Ended		12 Months Ended		24 Months Ended
	Sep. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)shares	Sep. 30, 2020USD ($)segmentshares	Sep. 30, 2019USD ($)shares	Dec. 31, 2019USD ($)segmentshares	Dec. 31, 2018USD ($)shares	Dec. 31, 2019USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Capitalized interest cost				$ (193,000)	$ 455,000	$ 608,000	$ 496,000
Interest expense	$ (191,000)		$ (191,000)	(569,000)	(567,000)	(758,000)	(710,000)
Cash and cash equivalents	4,369,000	$ 2,875,000		4,369,000		2,875,000	3,069,000	$ 2,875,000
Goodwill impairment charges	$ 0	0		$ 0	$ 0	0	0
License fee		0				$ 0	$ 3,000,000	0
Number of anti-dilutive shares (in shares) | shares	3,155,064		2,469,273	3,155,064	2,469,273	26,422,608	26,337,286
Number of reportable segments | segment				1		1
Revenue, net	$ 1,929,000		$ 994,000	$ 9,358,000	$ 2,011,000	$ 11,934,000	$ 1,358,000
Nexperia
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License fee		6,000,000				$ 6,000,000	$ 3,000,000	6,000,000
Recognition of contractual income								9,000,000
Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of anti-dilutive shares (in shares) | shares						23,933,949	23,933,949
Warrant
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of anti-dilutive shares (in shares) | shares	15,461		15,461	15,461	15,461	15,461	26,157
Stock options
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of anti-dilutive shares (in shares) | shares	2,327,423		2,453,812	2,327,423	2,453,812	2,473,198	2,377,180
Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Estimated Useful Life (in years)				3 years		3 years
Estimated useful life (in years)				3 years		3 years
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Estimated Useful Life (in years)				7 years			7 years
Estimated useful life (in years)				10 years		10 years
JAPAN
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash and cash equivalents	$ 41,000	$ 55,000		$ 41,000		$ 55,000	$ 264,000	$ 55,000
Percentage of cash and cash equivalents in foreign subsidiary	0.90%	1.90%		0.90%		1.90%	8.60%	1.90%
Revenue, net	$ 289,000		$ 6,000	$ 321,000	$ 25,000	$ 28,000	$ 49,000
UNITED STATES
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue, net	1,600,000		$ 988,000	9,000,000	$ 2,000,000	11,900,000	1,300,000
Restatement Adjustment
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Capitalized interest cost							150,000
Interest expense							150,000
Other Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash included in other assets	$ 75,000	$ 75,000		$ 75,000		$ 75,000	$ 75,000	$ 75,000

Nexperia Arrangement (Details)

Nexperia Arrangement (Details) - USD ($)	Apr. 04, 2018	Mar. 26, 2018	Jun. 30, 2020	Dec. 31, 2019	Oct. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Dec. 31, 2018	Oct. 31, 2018	Jul. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License fees	$ 9,000,000		$ 5,000,000		$ 3,000,000	$ 3,000,000		$ 3,000,000	$ 3,000,000		$ 9,000,000
Revolving loan	10,000,000
Deferred revenue								$ 3,000,000				$ 3,000,000
Series 3 Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of preferred stock	16,000,000	$ 16,000,000
Tranche A Loan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Long-term loan facility	5,000,000
Proceeds from Issuance of debt							$ 5,000,000
Repayments of Debt			5,000,000
Tranche B Loan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Long-term loan facility	8,000,000		$ 8,000,000	$ 8,000,000							8,000,000		$ 8,000,000
Proceeds from Issuance of debt										$ 8,000,000
Tranche B-1 Loan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Long-term loan facility	2,000,000			2,000,000							$ 2,000,000		$ 2,000,000
Proceeds from Issuance of debt				$ 2,000,000
Tranche C Loan
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from Issuance of debt												$ 10,000,000
Tranche B Loan After Merger [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Long-term loan facility	$ 10,000,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Hierarchy (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Promissory note	$ 0	$ 0	$ 0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Promissory note	0	0	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Promissory note	$ 16,327	$ 16,169	$ 15,852

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 inputs (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at January 1,		$ 16,169		$ 16,169	$ 15,852	$ 16,169	$ 15,852	$ 27,756
Interest expense accrued		150				112	150	364
Principal and interest expense paid							0	(13,328)
Increase in fair value							167	1,060
Fair value at December 31,	$ 16,327			16,327			16,169	15,852
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	16,327	16,169		16,327	15,852	16,169	15,852	15,852
Interest expense accrued		150				112	$ 150	$ 364
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	709	$ 167	$ 17	(46)	$ (101)	$ (46)
Level 3 | Fair Value, Recurring
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value at December 31,	16,327			16,327
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value	$ 16,327			$ 16,327

Concentration of Credit Risk _3

Concentration of Credit Risk and Significant Customers (Details) - Customer Concentration Risk	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue | Customer A
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	67.30%	14.60%
Revenue | Customer B
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	26.00%	51.10%
Accounts Receivable | Customer A
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	44.00%		60.00%
Accounts Receivable | Customer B
Concentration Risk [Line Items]
Percentage of revenue or accounts receivable	36.10%		20.40%

Inventory (Details)

Inventory (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 546,000		$ 546,000		$ 412,000	$ 258,000
Work in process	396,000		396,000		258,000	270,000
Finished goods	430,000		430,000		320,000	324,000
Total	1,372,000		1,372,000		990,000	852,000
Inventory write-off	$ 112,000	$ 0	$ 274,000	$ 0	$ 155,000	$ 0

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 20,914	$ 20,738
Less: accumulated depreciation and amortization	(19,144)	(18,606)
Property, Plant and Equipment, Net, Total	1,770	2,132	$ 1,432
Depreciation and amortization related to property, plant, and equipment	563	728
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 14,892	14,551
Estimated Useful Life (in years)	5 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 876	787
Estimated Useful Life (in years)	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 186	185
Estimated Useful Life (in years)	7 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 4,954	4,952
Estimated Useful Life (in years)	7 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6	$ 263

Intangible Assets - Finite-Live

Intangible Assets - Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Gross	$ 5,224	$ 5,224
Accumulated Amortization	(3,773)	(3,099)
Foreign Exchange Rate Changes	(138)	(167)
Total	1,313	1,958	$ 1,062
Amortization expense	653	646
Patents
Finite-Lived Intangible Assets [Line Items]
Gross	2,963	2,963
Accumulated Amortization	(1,679)	(1,383)
Foreign Exchange Rate Changes	0	0
Total	$ 1,284	$ 1,580
Estimated useful life (in years)	10 years	10 years
Developed technology - 150V
Finite-Lived Intangible Assets [Line Items]
Gross	$ 560	$ 560
Accumulated Amortization	(519)	(425)
Foreign Exchange Rate Changes	(34)	(41)
Total	$ 7	$ 94
Estimated useful life (in years)	6 years	6 years
Developed technology - 600V
Finite-Lived Intangible Assets [Line Items]
Gross	$ 1,701	$ 1,701
Accumulated Amortization	(1,575)	(1,291)
Foreign Exchange Rate Changes	(104)	(126)
Total	$ 22	$ 284
Estimated useful life (in years)	6 years	6 years

Intangible Assets - Estimated F

Intangible Assets - Estimated Future Amortization Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
2020		$ 325
2021		296
2022		296
2023		296
Thereafter		100
Total	$ 1,062	$ 1,313	$ 1,958

Debts - Additional Information

Debts - Additional Information (Details)	Feb. 12, 2020shares$ / shares	Oct. 31, 2017USD ($)	Feb. 29, 2020USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2019USD ($)	Apr. 04, 2018USD ($)	Apr. 02, 2018USD ($)	Dec. 31, 2015USD ($)$ / shares
Line of Credit Facility [Line Items]
Aggregate principal amount of loans outstanding					$ 35,901,000		$ 35,901,000		$ 41,206,000
Revolving loan													$ 10,000,000
Accrued interest on promissory note					38,000	$ 38,000	112,000	$ 112,000
Outstanding balance on line of credit facility					10,200,000		10,200,000		10,500,000	$ 10,300,000
Changes in fair value of promissory note					(709,000)	(17,000)	(46,000)	(101,000)	(167,000)	(1,060,000)
Interest expense					191,000	191,000	569,000	567,000	758,000	710,000
Conversion price per share on convertible note payable (in dollars per share) | $ / shares	$ 5.12
Maximum number of shares of common stock issuable (in shares) | shares	3,076,171
Interest expense paid							762,000	496,000	496,000	328,000
Proceeds from qualified financing		$ 10,000,000
Upper limit of estimated enterprise value		250,000,000
Lower limit of estimated enterprise value		$ 160,000,000
Accounts Payable and Accrued Liabilities [Member]
Line of Credit Facility [Line Items]
Interest expense					762,000
Yaskawa
Line of Credit Facility [Line Items]
Letter of intent for development activities			$ 4,000,000
Yaskawa | Forecast
Line of Credit Facility [Line Items]
Proceeds from Collaborators				$ 1,000,000
Loan and Security Agreement (LSA)
Line of Credit Facility [Line Items]
Long-term loan facility													15,000,000
Aggregate principal amount of loans outstanding					10,000,000		10,000,000		15,000,000
Tranche A Loan
Line of Credit Facility [Line Items]
Long-term loan facility													5,000,000
Tranche B Loan
Line of Credit Facility [Line Items]
Long-term loan facility									8,000,000		$ 8,000,000	$ 8,000,000	8,000,000
Tranche B-1 Loan
Line of Credit Facility [Line Items]
Long-term loan facility									2,000,000			$ 2,000,000	2,000,000
Tranche C Note
Line of Credit Facility [Line Items]
Long-term loan facility					$ 10,000,000		$ 10,000,000		10,000,000
Revolving loan													$ 10,000,000	$ 10,000,000
Interest rate per annum				6.00%	6.00%		6.00%						6.00%	6.00%
Accrued interest on promissory note					$ 153,000	153,000	$ 457,000	455,000	608,000	346,000
Interest expense paid									$ 496,000	0
Yaskawa Note
Line of Credit Facility [Line Items]
Interest rate per annum		1.00%		1.00%					1.00%
Changes in fair value of promissory note							46,000		$ 167,000	1,100,000
Unsecured subordinated convertible promissory note		$ 15,000,000			15,448,000		15,448,000		15,336,000	15,186,000
Interest expense					38,000	$ 38,000	112,000	$ 112,000	150,000	364,000
Accrued interest on promissory note					$ 448,000		$ 448,000		$ 336,000	$ 186,000
Maximum number of shares of common stock issuable (in shares) | shares	3,076,171
Percent of price paid by purchasers of preferred stock		80.00%
SCI Note
Line of Credit Facility [Line Items]
Interest rate per annum															6.00%
Notes payable															$ 10,000,000
IIDA Note
Line of Credit Facility [Line Items]
Interest rate per annum															1.00%
Conversion price per share on convertible note payable (in dollars per share) | $ / shares															$ 9.82380
Notes payable															$ 3,000,000

Debts - Notes Payable (Details)

Debts - Notes Payable (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Oct. 31, 2017
Line of Credit Facility [Line Items]
Changes in fair value of promissory note	$ (709)	$ (17)	$ (46)	$ (101)	$ (167)	$ (1,060)
Yaskawa Note
Line of Credit Facility [Line Items]
Interest rate per annum					1.00%		1.00%	1.00%
Unsecured subordinated convertible promissory note	15,448		15,448		$ 15,336	15,186		$ 15,000
Promissory note	$ 16,327		16,327		16,169	15,852
Changes in fair value of promissory note			$ 46		$ 167	$ 1,100

Debts - Maturities Schedule (De

Debts - Maturities Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2020	$ 10,000	$ 15,458
2021	15,748	10,000
2022		15,748
Total	35,901	$ 41,206
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	$ 10,153

Investment in Aizu Fujitsu Se_3

Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited ("AFSW") - Narrative (Details) ¥ in Millions	May 23, 2017USD ($)	May 23, 2017JPY (¥)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Variable Interest Entity [Line Items]
Investment in joint venture	$ 9,000	¥ 1			$ 5,327,000	$ 1,696,000	$ 2,698,000	$ 1,852,000
Unfunded commitment					$ 1,400,000
Put and call rights term							180 days
Forecast
Variable Interest Entity [Line Items]
Expected exercise price under certain conditions				$ 1
Minimum number of days before closing				60 days
Estimated time of regulatory approval, minimum				3 years
Estimated time of regulatory approval, maximum				6 months
Subsequent Event
Variable Interest Entity [Line Items]
Unfunded commitment				$ 1,300,000
Subsequent Event | Forecast
Variable Interest Entity [Line Items]
Agreement to maintain and continue AFSW, term				1 year
Aizu Fajitsu Semiconductor Wafer Solution Limited
Variable Interest Entity [Line Items]
Ownership percentage in entity					49.00%		49.00%
Additional financial support provided to investment			$ 2,698,000		$ 5,327,000		$ 2,698,000	1,852,000
Unfunded commitment					$ 1,700,000		$ 1,700,000	$ 659,000
Fujitsu Semiconductor Limited | Forecast
Variable Interest Entity [Line Items]
Purchase of additional interest					51.00%
Fujitsu Semiconductor Limited | Aizu Fajitsu Semiconductor Wafer Solution Limited
Variable Interest Entity [Line Items]
Ownership percentage in entity					51.00%		51.00%

Investment in Aizu Fujitsu Se_4

Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited ("AFSW") - Income Statement Information (Details) - Aizu Fajitsu Semiconductor Wafer Solution Limited - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary of Variable Interest Entities [Roll Forward]
Beginning balance	$ (1,688)	$ (1,688)	$ (659)	$ (98)
Investment	2,698	5,327	2,698	1,852
Loss	(3,703)	(5,218)	(3,703)	(2,404)
Effect of exchange rate change	$ (24)	(105)	(24)	(9)
Ending balance		$ (1,684)	$ (1,688)	$ (659)

Investment in Aizu Fujitsu Se_5

Investment in Aizu Fujitsu Semiconductor Wafer Solution Limited ("AFSW") - Summarized Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Assets, Current	$ 8,609		$ 8,609		$ 5,357	$ 4,825
Unfunded commitment to joint venture	1,684		1,684		1,688	659
Aizu Fajitsu Semiconductor Wafer Solution Limited
Variable Interest Entity [Line Items]
Assets, Current	1,138		1,138		3,733	4,096
Long-term assets	5,412		5,412		5,101	4,194
Unfunded commitment to joint venture	2,557		2,557		931	961
Net deficit	(26,550)		(26,550)		(15,359)	(7,662)
Variable Interest Entity, Measure of Activity [Abstract]
Sales	492	$ 2,613	2,278	$ 8,864	11,599	22,283
Gross loss	(3,170)	(835)	(8,515)	(4,002)	(4,849)	(2,523)
Net loss	(3,965)	$ (1,585)	(10,649)	$ (6,130)	(7,557)	(4,906)
Aizu Fajitsu Semiconductor Wafer Solution Limited | Fujitsu Semiconductor Limited
Variable Interest Entity [Line Items]
Accounts payable due to related parties	19,633		19,633		17,913	12,031
Aizu Fajitsu Semiconductor Wafer Solution Limited | Transphorm, Inc.
Variable Interest Entity [Line Items]
Accounts payable due to related parties	$ 10,910		$ 10,910		$ 5,349	$ 2,960

Commitment and Contingencies -

Commitment and Contingencies - Operating Lease Maturity Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2020	$ 180	$ 705
2021	571	489
2022	163	163
Total	$ 914	$ 1,357

Commitment and Contingencies _2

Commitment and Contingencies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitment to acquire equipment and services from vendors	$ 6,700		$ 6,700
Equipment purchased	616		4,100
Rent expense	228	$ 233	655	$ 672	$ 897	$ 915
Rental income from noncancelable sublease	45	$ 45	136	$ 136	182	$ 121
Future minimum rental payments to be received under sublease	78		78		$ 217
Unfunded commitment	1,400		1,400
Purchase Commitment, Amount Reimbursed	1,400		5,300
Accounts Payable, Purchase Commitment	$ 798		$ 798

Convertible Preferred Stock (De

Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)		23,946,403
Preferred stock, shares outstanding (in shares)	0	23,933,949
Preferred stock outstanding		$ 85,658
Par value of preferred stock (in usd per share)		$ 0.0001
Preferred stock liquidation value		$ 86,000
Series 1 Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)		12,438,704
Preferred stock, shares outstanding (in shares)		12,433,953
Preferred stock outstanding		$ 39,658
Par value of preferred stock (in usd per share)		$ 0.001
Preferred stock liquidation value		$ 40,000
Series 2 Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)		7,507,699
Preferred stock, shares outstanding (in shares)		7,499,996
Preferred stock outstanding		$ 30,000
Par value of preferred stock (in usd per share)		$ 0.001
Preferred stock liquidation value		$ 30,000
Series 3 Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)		4,000,000
Preferred stock, shares outstanding (in shares)		4,000,000
Preferred stock outstanding		$ 16,000
Par value of preferred stock (in usd per share)		$ 0.001
Preferred stock liquidation value		$ 16,000

Convertible Preferred Stock - N

Convertible Preferred Stock - Narrative (Details) - USD ($)	Apr. 04, 2018	Mar. 26, 2018	Dec. 31, 2019	Sep. 30, 2020	Feb. 11, 2020	Dec. 31, 2018
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			31,850,304			31,850,304
Underwritten public offering of common stock, minimum aggregate net proceeds			$ 40,000,000
Minimum ratio offering price per share of OIP			150.00%
Minimum aggregate proceeds of underwritten public offering of stock			$ 40,000,000
Series 1 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			12,433,953	0	51,680,254	12,433,953
Convertible preferred stock, par value (in usd per share)			$ 0.001	$ 0.0001		$ 0.001
Convertible preferred stock, liquidation rights per share			3.217
Convertible preferred stock, dividend rate			$ 0.25736
Series 1 Preferred Stock | KKR Phorm Investors L.P. (KKR)
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			12,433,953
Convertible preferred stock, par value (in usd per share)			$ 0.001
Convertible preferred stock, price per share (in usd per share)			$ 3.217
Issuance of preferred stock			$ 40,000,000
Series 2 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			7,499,996	0	38,760,190	7,499,996
Convertible preferred stock, par value (in usd per share)			$ 0.001	$ 0.0001		$ 0.001
Convertible preferred stock, liquidation rights per share			4
Convertible preferred stock, dividend rate			$ 0.32
Series 2 Preferred Stock | KKR Phorm Investors L.P. (KKR)
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			7,499,996
Convertible preferred stock, par value (in usd per share)			$ 0.001
Convertible preferred stock, price per share (in usd per share)			$ 4
Issuance of preferred stock			$ 30,000,000
Series 2 Preferred Stock | Other Investors | KKR Phorm Investors L.P. (KKR)
Class of Stock [Line Items]
Other investors with a small percentage			0.02%
Series 3 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)		4,000,000	4,000,000	0	31,850,304	4,000,000
Convertible preferred stock, par value (in usd per share)		$ 0.001	$ 0.001	$ 0.0001		$ 0.001
Convertible preferred stock, price per share (in usd per share)		$ 4
Issuance of preferred stock	$ 16,000,000	$ 16,000,000
Convertible preferred stock, liquidation rights per share			4
Convertible preferred stock, dividend rate			$ 0.32
Series 3 Preferred Stock | Other Investors
Class of Stock [Line Items]
Other investors with a small percentage		0.02%
Series 3 Preferred Stock | Nexperia
Class of Stock [Line Items]
Other investors with a small percentage		9.90%

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 12, 2020	Feb. 27, 2020	Sep. 30, 2020	Jun. 30, 2020	Feb. 29, 2020	Feb. 11, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Mar. 26, 2018	Feb. 28, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)							31,850,304			31,850,304
Convertible preferred stock, shares outstanding (in shares)							31,850,304
Common stock, shares issued (in shares)	4,171,571		35,266,496			50,325,662	4,220,998			4,219,606
Common stock outstanding (in shares)	4,171,571		35,266,496			50,325,662	4,220,998			4,219,606
Shares issued in connection with the Reverse Merger (in shares)	1,650,000
Shares redeemed (in shares)	52,773
Total common and preferred stock authorized for issuance (in shares)							755,000,000
Common stock, shares authorized (in shares)			750,000,000				29,012,034			29,012,034		24,867,458
Common stock, par value (in usd per share)			$ 0.0001				$ 0.0001			$ 0.001
Preferred stock, shares authorized (in shares)							23,946,403
Par value of preferred stock (in usd per share)							$ 0.0001
Preferred stock, shares issued (in shares)			0
Preferred stock, shares outstanding (in shares)			0				23,933,949
Aggregate gross proceeds from closing of offering	$ 1.8
Common Stock
Class of Stock [Line Items]
Common stock outstanding (in shares)			35,266,496	35,135,520			4,220,998	4,219,606	4,219,606	4,219,606			4,219,606
Shares issued in connection with the Reverse Merger (in shares)			1,650,000
Shares redeemed (in shares)			52,773
Price per share (in dollars per share)	$ 4
Private Placement
Class of Stock [Line Items]
Placement agent fees and closing expenses		$ 1.8
Private Placement | Common Stock
Class of Stock [Line Items]
Number of shares sold in private placement offering (in shares)		5,380,000
Price per share (in dollars per share)		$ 4
Aggregate gross proceeds from closing of offering		$ 21.5
Series 1 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			0			51,680,254	12,433,953			12,433,953
Convertible preferred stock, shares outstanding (in shares)			0			51,680,254	12,433,953			12,433,953
Common stock, shares issued (in shares)	12,433,953
Common stock outstanding (in shares)	12,433,953
Preferred stock, shares authorized (in shares)							12,438,704
Par value of preferred stock (in usd per share)							$ 0.001
Preferred stock, shares outstanding (in shares)							12,433,953
Series 2 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			0			38,760,190	7,499,996			7,499,996
Convertible preferred stock, shares outstanding (in shares)			0			38,760,190	7,499,996			7,499,996
Common stock, shares issued (in shares)	7,499,996
Common stock outstanding (in shares)	7,499,996
Preferred stock, shares authorized (in shares)							7,507,699
Par value of preferred stock (in usd per share)							$ 0.001
Preferred stock, shares outstanding (in shares)							7,499,996
Series 3 Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)			0			31,850,304	4,000,000			4,000,000	4,000,000
Convertible preferred stock, shares outstanding (in shares)			0			31,850,304	4,000,000			4,000,000
Common stock, shares issued (in shares)	4,000,000
Common stock outstanding (in shares)	4,000,000
Preferred stock, shares authorized (in shares)							4,000,000
Par value of preferred stock (in usd per share)							$ 0.001
Preferred stock, shares outstanding (in shares)							4,000,000
Common Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued (in shares)							4,220,998			4,219,606
Convertible preferred stock, shares outstanding (in shares)							4,220,998			4,219,606
Common stock, shares issued (in shares)			35,266,496
Common stock outstanding (in shares)			35,266,496
Common stock, shares authorized (in shares)			750,000,000		750,000,000
Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			5,000,000		5,000,000

Stockholders' Equity - Reserved

Stockholders' Equity - Reserved Common Stock (Details) - shares	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved for issuance (in shares)	5,057,986	27,985,690
Convertible Preferred Stock
Class of Stock [Line Items]
Common stock reserved for issuance (in shares)		23,946,403
Stock options
Class of Stock [Line Items]
Common stock reserved for issuance (in shares)	5,042,525	4,023,826
Warrant
Class of Stock [Line Items]
Common stock reserved for issuance (in shares)	15,461	15,461

Stockholders' Equity - Warrants

Stockholders' Equity - Warrants (Details) - $ / shares	Dec. 31, 2020	Sep. 30, 2020	Feb. 12, 2020	Feb. 11, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Number of shares (in shares)		15,461	15,461	186,535	15,461
November 2020
Class of Stock [Line Items]
Number of shares (in shares)		6,046			6,046
Exercise price (in usd per share)	$ 34.74	$ 34.74
February 2025
Class of Stock [Line Items]
Number of shares (in shares)		6,046			6,046
Exercise price (in usd per share)	34.74	$ 34.74
February 2025
Class of Stock [Line Items]
Number of shares (in shares)		3,369			3,369
Exercise price (in usd per share)	$ 54.41	$ 54.41

Stock Option Plans (Details)

Stock Option Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2007	Feb. 12, 2020	Jan. 01, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of stock options								10 years
Options available for grant (in shares)								1,550,628	1,648,038	1,589,381
Common stock reserved for issuance (in shares)	5,057,986	5,057,986				5,057,986		27,985,690
Options outstanding under The 2020 Plan (in shares)	2,327,423	2,327,423	2,453,812	2,454,687	2,342,440	2,327,423	2,453,812	2,473,130	2,377,180	2,435,837			2,461,923
Estimated weighted average amortization period (in years)						2 years 5 months 4 days	1 year 4 months 2 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 4.68	$ 4.68	$ 4.69	$ 4.74	$ 4.84	$ 4.68	$ 4.69	$ 4.67	$ 4.79	$ 4.80				$ 4.83
Options outstanding, weighted average remaining contractual term (in years)		6 years 1 month 28 days	7 years 21 days	6 years 3 months 29 days	7 years 1 month 28 days	6 years 1 month 28 days	7 years 21 days	6 years 10 months 2 days	7 years 5 months 15 days	8 years 4 months 17 days
Options outstanding, aggregate intrinsic value	$ 167	$ 167	$ 0	$ 0	$ 0	$ 167	$ 0	$ 0	$ 0	$ 0
Share-based Compensation Arrangement By Share-based Payment Award, Annual Shares Authorized, Percent Of Outstanding Shares	5.00%	5.00%				5.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						4 years
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)	5,042,525	5,042,525				5,042,525		4,023,826
Unrecognized stock-based compensation	$ 113	$ 113	$ 573			$ 113	$ 573	$ 464
Estimated weighted average amortization period (in years)						10 months 13 days	1 year 4 months 2 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	123,501	123,501				123,501
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		86,450				86,450
Restricted Stock [Member] | Share-based Payment Arrangement, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting in 1st 12 months						70.00%
Restricted Stock [Member] | Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						120 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average amortization period (in years)						2 years 7 months 20 days
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted		816,180				816,180
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		4,000				4,000
The 2020 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for issuance (in shares)	1,902,922	1,902,922				1,902,922
Equity Awards outstanding under The 2020 Plan (in shares)	816,180	816,180				816,180
Number of shares authorized by 2020 plan (in shares)	5,050,000	5,050,000				5,050,000
The 2020 Equity Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options authorized (in shares)						2,461,923
Share-based Compensation Arrangement by Share-based Payment Award, Annual Number of Additional Shares Authorized						5,000,000
Transphorm Technology 2007 Stock Plan and 2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding under The 2020 Plan (in shares)													29,703,285
Number of shares authorized by 2020 plan (in shares)	2,588,077	2,588,077				2,588,077
Transphorm Technology 2007 Stock Plan and 2015 Equity Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average amortization period (in years)								1 year 2 months 12 days
The 2007 Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of stock options											10 years
The 2007 Plan | Stock options | Share-based Payment Arrangement, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting in 1st 12 months												25.00%
Options available for grant (in shares)											0
Award vesting period												12 months
The 2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum percentage of fair market value of common stock								100.00%

Stock Option Plans - Schedule o

Stock Option Plans - Schedule of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, available for grant (in shares)				1,550,628	1,648,038	1,550,628	1,648,038	1,648,038	1,589,381
Beginning balance, options outstanding (in shares)		2,454,687	2,342,440	2,473,130	2,377,180	2,473,130	2,377,180	2,377,180	2,435,837
Options granted			125,183				183,109	209,908	46,005
Options exercised (in shares)		(3,475)				(6,821)		(1,392)
Options cancelled (in shares)		(123,789)	(13,811)			(138,886)	(106,477)	(112,498)	(104,662)
Ending balance, available for grant (in shares)								1,550,628	1,648,038	1,589,381
Ending balance, Options outstanding (in shares)	2,327,423	2,327,423	2,453,812	2,454,687	2,342,440	2,327,423	2,453,812	2,473,130	2,377,180	2,435,837
Exercisable at period end (in shares)	2,211,723	2,211,723	1,984,257			2,211,723	1,984,257	2,079,809
Weighted Average Exercise Price per Share
Beginning of period (in usd per share)		$ 4.74	$ 4.84	$ 4.67	$ 4.79	$ 4.67	$ 4.79	$ 4.79	$ 4.80
Options granted (in shares)			3.14				3.14	3.14	4.34
Options exercised (in dollars per share)		3.80				3.78		3.86
Options cancelled (in usd per share)		5.91	4.58			5.72	4.34	4.34	4.70
End of period (in usd per share)	$ 4.68	4.68	4.69	$ 4.74	$ 4.84	4.68	4.69	4.67	$ 4.79	$ 4.80
Exercisable at end of period (in usd per share)	$ 4.74	$ 4.74	$ 4.95			$ 4.74	$ 4.95	$ 4.95
Weighted Average Remaining Contractual Term (in Years)
Options outstanding, weighted average remaining contractual term (in years)		6 years 1 month 28 days	7 years 21 days	6 years 3 months 29 days	7 years 1 month 28 days	6 years 1 month 28 days	7 years 21 days	6 years 10 months 2 days	7 years 5 months 15 days	8 years 4 months 17 days
Options exercisable, weighted average remaining contractual term (in years)		6 years 29 days	6 years 10 months 6 days			6 years 29 days	6 years 10 months 6 days	6 years 7 months 24 days
Aggregate Intrinsic Value
Options outstanding, aggregate intrinsic value	$ 167	$ 167	$ 0	$ 0	$ 0	$ 167	$ 0	$ 0	$ 0	$ 0
Options exercisable, aggregate intrinsic value	$ 111	$ 111	$ 0			$ 111	$ 0	$ 0
Share Price	$ 4	$ 4				$ 4
Previously Reported
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning balance, options outstanding (in shares)				2,473,198		2,473,198
Ending balance, Options outstanding (in shares)								2,473,198
Restricted Stock [Member]
Aggregate Intrinsic Value
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	37,051	37,051		0		37,051		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 4,000	$ 4,000		$ 0		$ 4,000		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	123,501	123,501				123,501
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 4,000				$ 4,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(86,450)				(86,450)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		$ 4,000				$ 4,000

Stock Option Plans - Share-base

Stock Option Plans - Share-based Payment Agreement, Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock based compensation expense	$ 584	$ 159	$ 820	$ 435	$ 566	$ 585
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	812,180		812,180		0		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 4,000		$ 4,000		$ 0		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	816,180		816,180
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 4,000		$ 4,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(4,000)		(4,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 4,000		$ 4,000
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock based compensation expense	$ 17	24	$ 43	44	$ 60	41
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock based compensation expense	62	60	148	146	196	186
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock based compensation expense	11	8	23	24	30	45
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock based compensation expense	$ 494	$ 67	$ 606	$ 221	$ 280	$ 313

Stock Option Plans - Fair Value

Stock Option Plans - Fair Value Assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected life (in years)			5 years 5 months 15 days	5 years 10 months 2 days
Expected volatility, minimum			39.40%	38.10%
Expected volatility, maximum			39.80%	38.20%
Weighted average grant date fair value			$ 1.04	$ 0.84
Dividend yield			0.00%	0.00%
Estimated weighted average amortization period (in years)	2 years 5 months 4 days	1 year 4 months 2 days
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 3,410	$ 573
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average amortization period (in years)	2 years 7 months 20 days
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 3,297	$ 0
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated weighted average amortization period (in years)	10 months 13 days	1 year 4 months 2 days
Unrecognized stock-based compensation	$ 113	$ 573	$ 464
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.34%	2.51%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			1.94%	2.52%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Loss before tax expense	$ 6,740	$ 5,446	$ 13,197	$ 17,717	$ 15,283	$ 25,798
Increase in valuation allowance					2,700	6,400
Tax expense	$ 0	$ 0	$ 0	$ 0	0	0
Valuation allowance					49,403	46,749
Deferred tax assets, valuation allowance before adjustments					49,400	46,700
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Loss before tax expense					10,600	22,100
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					234,800
Operating loss carryforwards subject to expiration					207,500
Domestic Tax Authority | Tax Year 2018
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					18,500
Domestic Tax Authority | Tax Year 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					8,800
Domestic Tax Authority | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research tax credit carryforward					4,100	2,700
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Loss before tax expense					(4,600)
Foreign Tax Authority | National Tax Agency, Japan
Operating Loss Carryforwards [Line Items]
Loss before tax expense					4,700
Foreign Tax Authority | Transphorm Japan, Inc. | National Tax Agency, Japan
Operating Loss Carryforwards [Line Items]
Loss before tax expense					1,000	1,300
Foreign Tax Authority | Transphorm Aizu, Inc. | National Tax Agency, Japan
Operating Loss Carryforwards [Line Items]
Loss before tax expense					3,700	2,400
Foreign Tax Authority | Transphorm Epi, Inc. | National Tax Agency, Japan
Operating Loss Carryforwards [Line Items]
Loss before tax expense					(1)
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					152,700
Tax expense					1	$ 1
State and Local Jurisdiction | Tax Year 2018
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					15,300
State and Local Jurisdiction | Tax Year 2019
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					$ 5,100

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Tax Deferred Expense [Abstract]
Net operating loss carryforwards	$ 43,973	$ 42,181
Tax credits	4,535	3,808
California capitalized research and development	343	290
Depreciation	0	153
Others, net	602	318
Total deferred tax assets	49,453	46,750
Valuation allowance	49,403	46,749
Deferred tax asset, net of valuation allowance	50	1
Deferred tax liabilities:
Others, net	0	1
Fixed assets	50	0
Total deferred tax liabilities	50	1
Net deferred tax assets	$ 0	$ 0

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	21.00%
Research and development credit	(4.76%)	(1.61%)
Nondeductible expenses	3.18%	1.81%
Loss in joint venture	(7.44%)	(1.99%)
Foreign income tax rate difference	2.99%	(1.04%)
Others, net	(0.78%)	0.02%
Valuation allowance	(17.35%)	(17.79%)
Effective tax rate	0.00%	0.00%

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction
Accounts receivable due from related party	$ 12,300		$ 12,300		$ 5,800	$ 3,100
Accounts payable to related party					272	122
Noncontrolling Common Stockholder
Related Party Transaction
Accounts receivable due from related party	113		113		38	123
Accounts payable to related party	434		434		272
Noncontrolling Common Stockholder | Research and development
Related Party Transaction
Related party transaction expenses				$ 21
Noncontrolling Common Stockholder | Sale of Products
Related Party Transaction
Products sold to related party	113	$ 58	153	216	241	269
Noncontrolling Common Stockholder | License Maintenance Fee
Related Party Transaction
Related party transaction expenses	50		150	100	200	200
Common Stockholder
Related Party Transaction
Products sold to related party		178		293
Accounts receivable due from related party	532		532		426
Common Stockholder | Reimbursement for research and development
Related Party Transaction
Products sold to related party			408
Common Stockholder | Reimbursement from payroll related costs
Related Party Transaction
Related party transaction expenses					21	71
Common Stockholder | Sale of Products
Related Party Transaction
Products sold to related party	174		877			37
Common Stockholder | License Maintenance Fee
Related Party Transaction
Related Party Transaction, Reduction Of Expenses From Transactions With Related Party	38		113
Common Stockholder | License Fee Income
Related Party Transaction
Products sold to related party	31	38	5,100	113
Common Stockholder | Interest Expense
Related Party Transaction
Related party transaction expenses	153	153	457	455
Accounts receivable due from related party		16,000		16,000
Common Stockholder | Other Receivable
Related Party Transaction
Accounts receivable due from related party	338		338
Common Stockholder | EPI Gen 4 Wafer Growth Sales [Member]
Related Party Transaction
Products sold to related party	280	0	280	0
Common Stockholder | Reimbursements In License Maintenance [Member]
Related Party Transaction
Products sold to related party		16,000
Convertible Preferred Stockholder
Related Party Transaction
Accounts receivable due from related party					426	54
Convertible Preferred Stockholder | Reimbursement for research and development
Related Party Transaction
Products sold to related party					195
Convertible Preferred Stockholder | Sale of Products
Related Party Transaction
Products sold to related party					504	166
Convertible Preferred Stockholder | License Fee Income
Related Party Transaction
Products sold to related party					9,200	3,000
Corporate Joint Venture
Related Party Transaction
Accounts receivable due from related party	11,300		11,300		5,300	3,000
Corporate Joint Venture | Related Party Services
Related Party Transaction
Related party transaction expenses	60	379	228	477	211	751
Corporate Joint Venture | Research and development
Related Party Transaction
Related party transaction expenses	418	117	1,100	320	695	560
Corporate Joint Venture | Reimbursement for research and development
Related Party Transaction
Related party transaction expenses			408		195
Corporate Joint Venture | Commitment For Services
Related Party Transaction
Related party transaction expenses			84		444
Corporate Joint Venture | Reimbursement from payroll related costs
Related Party Transaction
Related party transaction expenses	$ 10	$ 6	$ 11	$ 21	$ 14	175
Noncontrolling Common Stockholder And Noteholder
Related Party Transaction
Accounts receivable due from related party						$ 10

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)

Mar. 26, 2020

Feb. 12, 2020

Feb. 27, 2020

Mar. 31, 2020

Sep. 30, 2020

Sep. 30, 2019

May 31, 2020

Dec. 31, 2020

Dec. 31, 2020

Sep. 30, 2020

Sep. 30, 2019

Dec. 31, 2019

Dec. 31, 2018

Feb. 29, 2020

Apr. 04, 2018

Subsequent Event [Line Items]

Aggregate gross proceeds from closing of offering

$ 1,800,000

Options granted

125,183

183,109

209,908

46,005

Options granted (in shares)

$ 3.14

$ 3.14

$ 3.14

$ 4.34

Term of stock options

10 years

Commitment to acquire equipment and services from vendors

$ 6,700,000

$ 6,700,000

Equipment purchased

616,000

4,100,000

Unfunded commitment

$ 1,400,000

$ 1,400,000

The 2020 Equity Incentive Plan

Subsequent Event [Line Items]

Number of shares authorized by 2020 plan (in shares)

5,050,000

5,050,000

Private Placement

Subsequent Event [Line Items]

Placement agent fees and closing expenses

$ 1,800,000

Tranche A Loan

Subsequent Event [Line Items]

Long-term loan facility

$ 5,000,000

Forecast

Subsequent Event [Line Items]

Expected exercise price under certain conditions

$ 1

Minimum number of days before closing

60 days

Estimated time of regulatory approval, minimum

3 years

Estimated time of regulatory approval, maximum

6 months

Forecast | Fujitsu Semiconductor Limited

Subsequent Event [Line Items]

Purchase of additional interest

51.00%

51.00%

Subsequent Event

Subsequent Event [Line Items]

Options granted (in shares)

$ 4

Term of stock options

10 years

Commitment to acquire equipment and services from vendors

$ 4,900,000

$ 4,900,000

Equipment purchased

$ 3,600,000

Unfunded commitment

1,300,000

$ 1,300,000

Subsequent Event | The 2020 Equity Incentive Plan

Subsequent Event [Line Items]

Number of shares authorized by 2020 plan (in shares)

5,050,000

Options granted

1,052,017

Subsequent Event | Private Placement | Common Stock

Subsequent Event [Line Items]

Number of shares sold in private placement offering (in shares)

5,365,000

15,000

Sale Of Stock, Shares Authorized To Be Sold

12,500,000

Price per share (in dollars per share)

$ 4

Aggregate gross proceeds from closing of offering

$ 21,500,000

Subsequent Event | Private Placement | Common Stock | Other Assets

Subsequent Event [Line Items]

Aggregate gross proceeds from closing of offering

$ 177,000

Subsequent Event | Forecast

Subsequent Event [Line Items]

Letter of intent to provide funding

$ 4,000,000

1,000,000

Cost reimbursable sub award

$ 646,000