PDF Solutions (PDFS) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Document Information [Line Items]
Entity Central Index Key	0001120914
Entity Registrant Name	PDF SOLUTIONS INC
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	000-31311
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	25-1701361
Entity Address, Address Line One	2858 De La Cruz Blvd.
Entity Address, City or Town	Santa Clara
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95050
City Area Code	408
Local Phone Number	280-7900
Title of 12(b) Security	Common Stock, $0.00015 par value
Trading Symbol	PDFS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		36,929,776

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 74,287	$ 30,315
Short-term investments	57,999	114,981
Accounts receivable, net of allowance for doubtful accounts of $963 in 2021 and 2020	34,785	34,140
Prepaid expenses and other current assets	11,375	13,944
Total current assets	178,446	193,380
Property and equipment, net	38,147	39,242
Operating lease right-of-use assets, net	6,171	6,672
Goodwill	15,305	15,774
Intangible assets, net	23,724	24,573
Deferred tax assets, net	198	249
Other non-current assets	9,140	7,690
Total assets	271,131	287,580
Current liabilities:
Accounts payable	967	4,399
Accrued compensation and related benefits	6,204	8,339
Accrued and other current liabilities	8,271	6,309
Operating lease liabilities – current portion	1,742	1,926
Deferred revenues – current portion	17,578	19,895
Billings in excess of recognized revenues	339	1,337
Total current liabilities	35,101	42,205
Long-term income taxes payable	2,911	2,956
Non-current operating lease liabilities	6,151	6,516
Other non-current liabilities	(1,715)	(1,397)
Total liabilities	45,878	53,074
Commitments and contingencies (Note 13)
Stockholders’ equity:
Preferred stock, $0.00015 par value, 5,000 shares authorized, no shares issued and outstanding	0	0
Common stock, $0.00015 par value, 70,000 shares authorized; shares issued 46,804 and 46,400, respectively; shares outstanding 36,929 and 36,850, respectively	6	6
Additional paid-in-capital	412,031	407,173
Treasury stock at cost, 9,874 and 9,550 shares, respectively	(102,201)	(96,215)
Accumulated deficit	(83,830)	(76,233)
Accumulated other comprehensive loss	(753)	(225)
Total stockholders’ equity	225,253	234,506
Total liabilities and stockholders’ equity	$ 271,131	$ 287,580

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable, allowance for doubtful accounts	$ 963	$ 963
Preferred stock, par value (in dollars per share)	$ 0.00015	$ 0.00015
Preferred stock, shares authorized (in shares)	5,000	5,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.00015	$ 0.00015
Common stock, shares authorized (in shares)	70,000	70,000
Common stock, shares issued (in shares)	46,804	46,400
Common stock, shares outstanding (in shares)	36,929	36,850
Treasury stock, shares (in shares)	9,874	9,550

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Revenues	$ 24,200	$ 21,158
Costs and Expenses:
Costs of revenues	10,663	8,487
Research and development	10,841	8,590
Selling, general and administrative	9,464	7,895
Amortization of other acquired intangible assets	314	173
Interest and other expense (income), net	(441)	20
Loss before income taxes	(6,641)	(4,007)
Income tax expense (benefit)	956	(3,479)
Net loss	(7,597)	(528)
Other comprehensive loss:
Foreign currency translation adjustments, net of tax	(530)	(166)
Change in unrealized losses related to available-for-sale debt securities, net of tax	2	0
Total other comprehensive loss	(528)	(166)
Comprehensive loss	$ (8,125)	$ (694)
Net loss per share, basic and diluted (in dollars per share)	$ (0.21)	$ (0.02)
Weighted average common shares used to calculate net loss per share, basic and diluted (in shares)	36,974	32,703
Analytics [Member]
Revenues:
Revenues	$ 19,393	$ 13,248
Integrated Yield Ramp [Member]
Revenues:
Revenues	$ 4,807	$ 7,910

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balances (in shares) at Dec. 31, 2019	32,503		9,294
Balances at Dec. 31, 2019	$ 5	$ 325,197	$ (91,695)	$ (35,870)	$ (1,480)	$ 196,157
Issuance of common stock in connection with employee stock purchase plan (in shares)	89		0
Issuance of common stock in connection with employee stock purchase plan	$ 0	810	$ 0	0	0	810
Issuance of common stock in connection with exercise of options (in shares)	21		0
Issuance of common stock in connection with exercise of options	$ 0	161	$ 0	0	0	161
Vesting of restricted stock units (in shares)	182		0
Vesting of restricted stock units	$ 0	0	$ 0	0	0	0
Purchases of treasury stock in connection with tax withholdings on restricted stock grants (in shares)	0		93
Purchases of treasury stock in connection with tax withholdings on restricted stock grants	$ 0	0	$ (1,478)	0	0	(1,478)
Stock-based compensation expense	0	3,513	0	0	0	3,513
Comprehensive income (loss)	$ 0	0	$ 0	(528)	(166)	(694)
Balances (in shares) at Mar. 31, 2020	32,795		9,387
Balances at Mar. 31, 2020	$ 5	329,681	$ (93,173)	(36,398)	(1,646)	198,469
Balances (in shares) at Dec. 31, 2020	36,850		9,550
Balances at Dec. 31, 2020	$ 6	407,173	$ (96,215)	(76,233)	(225)	234,506
Issuance of common stock in connection with employee stock purchase plan (in shares)	100		0
Issuance of common stock in connection with employee stock purchase plan	$ 0	921	$ 0	0	0	$ 921
Issuance of common stock in connection with exercise of options (in shares)	81		0			81
Issuance of common stock in connection with exercise of options	$ 0	568	$ 0	0	0	$ 568
Vesting of restricted stock units (in shares)	149		0
Vesting of restricted stock units	$ 0	0	$ 0	0	0	0
Purchases of treasury stock in connection with tax withholdings on restricted stock grants (in shares)	0		73
Purchases of treasury stock in connection with tax withholdings on restricted stock grants	$ 0	0	$ (1,463)	0	0	(1,463)
Repurchase of common stock (in shares)	(251)		251
Repurchase of common stock	$ 0	0	$ (4,523)	0	0	(4,523)
Stock-based compensation expense	0	3,369	0	0		3,369
Comprehensive income (loss)	$ 0	0	$ 0	(7,597)	(528)	(8,125)
Balances (in shares) at Mar. 31, 2021	36,929		9,874
Balances at Mar. 31, 2021	$ 6	$ 412,031	$ (102,201)	$ (83,830)	$ (753)	$ 225,253

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021		Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (7,597)		$ (528)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	1,718		1,667
Stock-based compensation expense	3,369		3,368
Amortization of acquired intangible assets	(849)		(317)
Amortization of costs capitalized to obtain revenue contracts	(165)		(124)
Reversal of allowance for doubtful accounts	0		(60)
Loss on disposal of property and equipment	5		0
Accretion of discount on short-term investments	(20)		0
Deferred taxes	(55)		(45)
Changes in operating assets and liabilities:
Accounts receivable	(677)		3,348
Prepaid expenses and other current assets	2,839		(1,910)
Operating lease right-of-use assets	476		241
Other non-current assets	339		(1,906)
Accounts payable	(4,109)		163
Accrued compensation and related benefits	(2,059)		(271)
Accrued and other liabilities	(162)		(589)
Deferred revenues	(1,994)		972
Billings in excess of recognized revenues	(998)		679
Operating lease liabilities	(524)		(280)
Net cash provided by (used in) operating activities	(8,325)		5,380
Cash flows from investing activities:
Proceeds from maturities of short-term investments	68,000		0
Purchases of short-term investments	(10,997)		0
Purchases of property and equipment	(586)		(2,068)
Net cash provided by (used in) investing activities	56,417		(2,068)
Cash flows from financing activities:
Proceeds from exercise of stock options	568		161
Proceeds from employee stock purchase plan	921		810
Payments for taxes related to net share settlement of equity awards	(1,463)		(1,478)
Repurchases of common stock	(4,523)		0
Net cash used in financing activities	(4,497)		(507)
Effect of exchange rate changes on cash and cash equivalents	(104)		(25)
Net change in cash, cash equivalents, and restricted cash	43,491		2,780
Cash, cash equivalents, and restricted cash at beginning of period	33,815		97,605
Cash, cash equivalents, and restricted cash at end of period	77,306		100,385
Reconciliation of cash, cash equivalents, and restricted cash to the balance sheets:
Cash and cash equivalents	74,287		100,385
Restricted cash	3,019		0
Cash, cash equivalents, and restricted cash at end of period	77,306		100,385
Supplemental disclosure of cash flow information:
Cash paid during the period for taxes	530		968
Cash paid for amounts included in the measurement of operating lease liabilities	651		397
Supplemental disclosure of noncash information:
Stock-based compensation capitalized as software development costs	0		128
Property and equipment received and accrued in accounts payable and accrued and other liabilities	181		796
Release of restricted cash reducing goodwill due to the acquisition purchase price adjustment	$ 469	[1]	$ 0
[1]	Goodwill adjustment was recorded within the measurement period with a corresponding reduction in the Holdback Amount. See Note 4, Business Combination.

Note 1 - Basis of Presentation

Note 1 - Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1. Basis of Presentation The interim unaudited condensed consolidated financial statements included herein have been prepared by PDF Solutions, Inc. (the “Company”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”), including the instructions to the Quarterly Report on Form 10 10 X. not may 10 December 31, 2020 The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries after the elimination of all intercompany balances and transactions. The condensed consolidated balance sheet at December 31, 2020 not Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (“U.S. 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. Significant estimates in these financial statements include revenue recognition, assumptions made in analysis of allowance for doubtful accounts, impairment of goodwill and long-lived assets, realization of deferred tax assets (DTAs), and accounting for lease obligations, stock-based compensation expense, and income taxes. Actual results could differ from those estimates. The global COVID- 19 may 2020 first 2021 may 2020 2021. may 19 may 19 not may may Recent Accounting Standards Accounting Standards Adopted In December 2019, No. 2019 12, 740 740 first 2021 January 1, 2021, not In January 2020, No. 2020 01 321 323 815 321, 323, 815. 321 323 815 December 15, 2020. January 1, 2021, not Accounting Standards Not In June 2016, No. 2016 13, 326 2016 13 No. 2016 13 No. 2016 13, No. 2018 19, 326, No. 2019 04, 326, 815, 825, No. 2019 05, 326 No. 2016 13, No. 2019 10 326 815 842 No. 2019 11 326, not No. 2016 13. No. 2016 13. Additionally, ASU No. 2019 10 December 15, 2022, 2023 February 2020, 2020 02, No. 2016 13. 326 326, not In August 2020, No. 2020 06, 470 20 815 20 December 15, 2023 not Management has reviewed other recently issued accounting pronouncements issued or proposed by the FASB, and does not

Note 2 - Revenue From Contracts

Note 2 - Revenue From Contracts With Customers	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Revenue from Contract with Customer [Text Block]	2. The Company derives revenue from two The Company recognizes revenue in accordance with FASB Accounting Standard Codification (“ASC”) Topic 606, Revenue from Contracts with Customers 606” 606 The Company determines revenue recognition through the following five ● Identification of the contract, or contracts, with a customer ● Identification of the performance obligations in the contract ● Determination of the transaction price ● Allocation of the transaction price to the performance obligations in the contract ● Recognition of revenue when, or as, performance obligations are satisfied The Company accounts for a contract when it has approval and commitment from both parties, the rights of the parties are identified, payment terms are identified, the contract has commercial substance, and collectability of consideration is probable. Contracts with multiple performance obligations The Company enters into contracts that can include various combinations of licenses, products and services, some of which are distinct and are accounted for as separate performance obligations. For contracts with multiple performance obligations, the Company allocates the transaction price of the contract to each performance obligation on a relative basis using standalone selling price. Analytics Revenue Analytics revenue is derived from the following primary offerings: licenses and services for standalone Software (which is primarily Exensio and Cimetrix products), SaaS (which is primarily Exensio products), and DFI™ and CV® systems that do not Revenue from standalone Software is recognized depending on whether the license is perpetual or time-based. Perpetual ( one Revenue from SaaS arrangements, which allow for the use of a cloud-based software product or service over a contractually determined period of time without the customer having to take possession of software, is accounted for as a subscription and is recognized as revenue ratably, on a straight-line basis, over the subscription period beginning on the date the service is first Revenue from DFI™ and CV® systems that do not not Integrated Yield Ramp Revenue Integrated Yield Ramp revenue is derived from the Company’s fixed-fee engagements that include performance incentives based on customers’ yield achievement (which consists primarily of Gainshare royalties) typically based on customer’s wafer shipments, pertaining to these fixed-price contracts, which royalties are variable. Revenue under these project–based contracts, which are delivered over a specific period of time, typically for a fixed fee component paid on a set schedule, is recognized as services are performed using a percentage of completion method based on costs or labor-inputs, whichever is the most appropriate measure of the progress towards completion of the contract. Where there are distinct performance obligations, the Company allocates revenue to all deliverables based on their SSPs and allocates the transaction price of the contract to each performance obligation on a relative basis using SSP. Similar to the services provided in connection with DFI™ and CV® systems that are contributing to Analytics revenue, due to the nature of the work performed in these arrangements, the estimation of percentage of completion method is complex and subject to many variables that require significant judgement. Please refer to “Significant Judgments” section of this Note for further discussion. The Gainshare royalty contained in IYR contracts is a variable fee related to continued usage of the Company’s intellectual property after the fixed-fee service period ends, based on a customer’s yield achievement. Revenue derived from Gainshare is contingent upon the Company’s customers reaching certain defined production yield levels. Gainshare royalty periods are generally subsequent to the delivery of all contractual services and performance obligations. The Company records Gainshare as a usage-based royalty derived from customers’ usage of intellectual property and records it in the same period in which the usage occurs. Disaggregation of Revenue The Company disaggregates revenue from contracts with customers into the timing of the transfer of goods and services and the geographical regions. The Company determined that disaggregating revenue into these categories achieves the disclosure objective to depict how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. The Company’s performance obligations are satisfied either over time or at a point-in-time. The following table represents a disaggregation of revenue by timing of revenue: Three Months Ended March 31, 2021 2020 Over time 50 % 58 % Point-in-time 50 % 42 % Total 100 % 100 % International revenues accounted for approximately 65% of our total revenues during the three March 31, 2021 three March 31, 2020 11, Customer and Geographic Information Significant Judgments Judgments and estimates are required under ASC 606. 606 may may For revenue under project-based contracts for fixed-price implementation services, revenue is recognized as services are performed using a percentage-of-completion method based on costs or labor-hours input method, whichever is the most appropriate measure of the progress towards completion of the contract. Due to the nature of the work performed in these arrangements, the estimation of percentage of completion method is complex, subject to many variables and requires significant judgment. Key factors reviewed by the Company to estimate costs to complete each contract are future labor and product costs and expected productivity efficiencies. If circumstances arise that change the original estimates of revenues, costs, or extent of progress toward completion, revisions to the estimates are made. These revisions may The Company’s contracts with customers often include promises to transfer products, licenses software and provide services, including professional services, technical support services, and rights to unspecified updates to a customer. Determining whether licenses and services are distinct performance obligations that should be accounted for separately, or not not not may The Company is required to record Gainshare royalty revenue in the same period in which the usage occurs. Because the Company generally does not Contract Balances The Company performs its obligations under a contract with a customer by licensing software or providing services in exchange for consideration from the customer. The timing of the Company’s performance often differs from the timing of the customer’s payment, which results in the recognition of a receivable, a contract asset or a contract liability. The Company classifies the right to consideration in exchange for software or services transferred to a customer as either a receivable or a contract asset. A receivable is a right to consideration that is unconditional, as compared to a contract asset, which is a right to consideration that is conditional upon factors other than the passage of time. The majority of the Company’s contract assets represent unbilled amounts related to fixed-price service contracts when the revenue recognized exceeds the amount billed to the customer. The contract assets are generally classified as current and are recorded on a net basis with deferred revenue (i.e. contract liabilities) at the contract level. At March 31, 2021 December 31, 2020 not Deferred revenues consist substantially of amounts invoiced in advance of revenue recognition and are recognized as the revenue recognition criteria are met. Deferred revenues that will be recognized during the succeeding twelve March 31, 2021 December 31, 2020 three March 31, 2021 2020 At March 31, 2021 two three not not The adjustment to revenue recognized in the three March 31, 2021 2020 Costs to obtain or fulfill a contract The Company capitalizes the incremental costs to obtain or fulfill a contract with a customer, including direct sales commissions and related fees, when it expects to recover those costs. Amortization expense related to these capitalized costs is recognized over the period associated with the revenue from which the cost was incurred. Total capitalized direct sales commission costs included in prepaid expenses and other current assets in the accompanying Condensed Consolidated Balance Sheets as of March 31, 2021 December 31, 2020 March 31, 2021 December 31, 2020 three March 31, 2021 2020 no Certain eligible initial project costs are capitalized when the costs relate directly to the contract, the costs generate or enhance resources of the Company that will be used in satisfying the performance obligation in the future, and the costs are expected to be recovered. These costs primarily consist of transition and set-up costs related to the installation of systems and processes and other deferred fulfillment costs eligible for capitalization. Capitalized costs are amortized consistent with the transfer to the customer of the services to which the asset relates and recorded as a component of cost of revenues. The Company also incurs certain direct costs to provide services in relation to the specific anticipated contracts. The Company recognizes such costs as a component of cost of revenues, the timing of which is dependent upon identification of a contract arrangement. At the end of the reporting period, the Company evaluates its deferred costs for their probable recoverability. The deferred costs balance included in prepaid expenses and other current assets and in other non-current assets in the accompanying Condensed Consolidated Balance Sheets March 31, 2021 December 31, 2020 no no no The Company does not one not three March 31, 2021 2020 .

Note 3 - Strategic Partnership

Note 3 - Strategic Partnership Agreement With Advantest and Related Party Transactions	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Related Party Transactions Disclosure [Text Block]	3. On July 29, 2020, ● A Securities Purchase Agreement for the purchase by Advantest of an aggregate of 3,306,924 shares of the Company’s common stock for aggregate gross proceeds of $65.2 million and a related Stockholder Agreement. ● An Amendment #1 March 25, 2020, three March 31, 2021 March 31, 2021 ● An Amended and Restated Master Development Agreement with Advantest, pursuant to which the Company and Advantest agreed to collaborate on extensions to or combinations of both of their existing technology and new technology to address mutual customers’ needs through one not three March 31, 2021. ● A Master Commercial Terms and Support Services Agreement for the commercialization and support of integrated products of the Company and Advantest that are the outcome of the above development agreement. No three March 31, 2021. There was no The Company carries out transactions with Advantest on arm’s length commercial customary terms. For more information about these agreements with Advantest, see Note 3, Strategic Partnership Agreement with Advantest and Related Party Transactions 8. 10 December 31, 2020

Note 4 - Business Combination

Note 4 - Business Combination	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Business Combination Disclosure [Text Block]	4. On December 1, 2020 ( 2020 2020, three March 31, 2021, twelve The Company is required to maintain cash specifically designated to pay for the Holdback Amount, which the Company has classified as restricted cash. Restricted cash amounted to $3.0 million and $3.5 million as of March 31, 2021 December 31, 2020 The Company is still finalizing the allocation of the purchase price to the individual assets acquired. Accordingly, the estimates set forth below are preliminary and are subject to change during the measurement period, which is not one three March 31, 2021 2020, not three March 31, 2021 March 31, 2021, Amount Amortization Period (Years) Assets Fair value of tangible assets (including cash of $5,900) $ 8,403 Fair value of intangible assets: Developed technology 12,541 8 In-process R&D 3,635 N/A Customer relationships 1,967 10 Noncompetition agreements 848 3 Tradenames and trademarks 808 10 Goodwill 13,012 N/A Total assets acquired $ 41,214 Liabilities Accounts payable and accrued expenses $ 1,437 Deferred revenue 391 Operating lease liabilities 132 Deferred tax liabilities 1,743 Total liabilities assumed $ 3,703 Total purchase price allocation $ 37,511 Pursuant to the merger agreement, the Company will also pay approximately $1.4 million to certain employees, subject to their continued employment with Cimetrix or the Company, at various scheduled payout dates through the second 2024 . March 31, 2021, March 31, 2021 December 31, 2020 Transaction expenses related to the acquisition of Cimetrix amounted to $1.6 million in 2020 . three March 31, 2021 The financial results of the acquisition of Cimetrix were considered immaterial for purposes of unaudited pro forma financial disclosures.

Note 5 - Balance Sheet Componen

Note 5 - Balance Sheet Components	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Supplemental Balance Sheet Disclosures [Text Block]	5. Accounts receivable Accounts receivable include amounts that are unbilled at the end of the period that are expected to be billed and collected within a 12 March 31, 2021 December 31, 2020 not 12 March 31, 2021 December 31, 2020 Property and equipment Property and equipment, net consist of the following (in thousands): March 31, December 31, 2021 2020 Computer equipment $ 11,595 $ 11,585 Software 5,435 5,451 Furniture, fixtures and equipment 2,501 2,507 Leasehold improvements 6,255 6,255 Laboratory and other equipment 3,571 3,451 Test equipment 25,977 26,010 Construction-in-progress 20,699 20,278 76,033 75,537 Less: accumulated depreciation and amortization (37,886 ) (36,295 ) Total $ 38,147 $ 39,242 Test equipment includes DFI™ assets at customer sites that are contributing to DFI™ revenues. The construction-in-progress balance related to construction of DFI™ assets totaled $19.3 million and $18.9 million as of March 31, 2021 December 31, 2020 three March 31, 2021 2020 Goodwill and Intangible Assets, Net The change in the carrying amount of goodwill during the three March 31, 2021 March 31, 2021 Balance at beginning of period $ 15,774 Measurement period acquisition adjustment (1) (469 ) Balance at end of period $ 15,305 _________________________ ( 1 Goodwill adjustment was recorded within the measurement period with a corresponding reduction in the Holdback Amount. See Note 4, Business Combination There were no impairments to goodwill during the three March 31, 2021 Intangible assets, net, consisted of the following (in thousands): March 31, 2021 December 31, 2020 Amortization Gross Net Gross Net Period Carrying Accumulated Carrying Carrying Accumulated Carrying (Years) Amount Amortization Amount Amount Amortization Amount Acquired identifiable intangibles: Customer relationships 1 ‒ 10 $ 9,407 $ (5,558 ) $ 3,849 $ 9,407 $ (5,398 ) $ 4,009 Developed technology 4 ‒ 9 30,000 (15,570 ) 14,430 30,000 (14,987 ) 15,013 Tradename and trademarks 2 ‒ 10 1,598 (732 ) 866 1,598 (706 ) 892 Patent 7 ‒ 10 1,800 (1,610 ) 190 1,800 (1,600 ) 200 Noncompetition agreements 3 848 (94 ) 754 848 (24 ) 824 In-process R&D * 3,635 — 3,635 3,635 — 3,635 Total $ 47,288 $ (23,564 ) $ 23,724 $ 47,288 $ (22,715 ) $ 24,573 _________________________________ * Non-amortizing intangible asset The Company expects annual amortization of acquired identifiable intangible assets to be as follows (in thousands): Year Ending December 31, Amount 2021 (remaining nine months) $ 2,372 2022 3,013 2023 2,990 2024 2,592 2025 2,427 2026 and thereafter 6,695 Total future amortization expense $ 20,089 Intangible assets are amortized over their useful lives unless these lives are determined to be indefinite. The weighted average amortization period for acquired identifiable intangible assets was 6.1 years as of March 31, 2021 three March 31, 2021 2020 may not three March 31, 2021

Note 6 - Leases

Note 6 - Leases	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Lessee, Operating Leases [Text Block]	6 . LEASES The Company leases administrative and sales offices and certain equipment under non-cancellable operating leases, which contain various renewal options and, in some cases, require payment of common area costs, taxes and utilities. These operating leases expire at various dates through 2028. no March 31, 2021 December 31, 2020 Lease expense was comprised of the following (in thousands): Three Months Ended March 31, 2021 2020 Operating lease expense $ 485 $ 455 Short-term lease and variable lease expense (1) 174 147 Total lease expense $ 659 $ 602 __________________________ ( 1 Leases with an initial term of 12 not Supplemental balance sheet information related to operating leases was as follows: March 31, December 31, 2021 2020 Weighted average remaining lease term under operating ROU leases (in years) 6.3 6.4 Weighted average discount rate for operating lease liabilities 5.24 % 5.24 % Operating lease ROU assets obtained (in thousands) $ — $ 286 Maturities of operating lease liabilities as of March 31, 2021 Year Ending December 31, Amount (1) 2021 (remaining nine months) $ 1,453 2022 1,699 2023 1,385 2024 1,074 2025 1,089 2026 and thereafter 2,703 Total future minimum lease payments $ 9,403 Less: Interest (2) (1,510 ) Present value of future minimum lease payments under operating lease liabilities (3) $ 7,893 ( 1 As of March 31, 2021 ( 2 Calculated using incremental borrowing interest rate for each lease. ( 3 Includes the current portion of operating lease liabilities of $1.7 million as of March 31, 2021

Note 7 - Stockholders' Equity

Note 7 - Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Shareholders' Equity and Share-based Payments [Text Block]	7. Issuance of Common Stock On July 30, 2020, July 29, 2020. Stock Repurchase Program On May 28, 2020, 2018 “2018 May 29, 2018, May 28, 2020, 2018 On June 4, 2020, “2020 10b5 1 two three March 31, 2021 2020

Note 8 - Employee Benefit Plans

Note 8 - Employee Benefit Plans	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Compensation and Employee Benefit Plans [Text Block]	8. On March 31, 2021 Employee Stock Purchase Plan In July 2001, ten twenty-four four six 2020 2010 June 22, 2030 not May 17, 2020. no January 31, 2022. The Company estimated the fair value of purchase rights granted under the Purchase Plan during the period using the Black-Scholes-Merton option-pricing model with the following weighted average assumptions, resulting in the following weighted average fair values: Three Months Ended March 31, 2021 2020 Expected life (in years) 1.25 1.25 Volatility 34.25 % 34.25 % Risk-free interest rate 1.43 % 1.43 % Expected dividend — — Weighted average fair value of purchase rights granted during the period $ 4.83 $ 4.83 During the three March 31, 2021 2020 March 31, 2021 Stock Incentive Plans On November 16, 2011, 2011 “2011 2011 may 2001 2001, 2011 “2001 2001 November 16, 2011. 2011 no ten four Stock options granted under the 2001 ten four no may 2001 2001 As of March 31, 2021 2011 2011 2001 2011 March 31, 2021 March 31, 2021 no 2011 2001 The Company estimated the fair value of share-based awards granted under the 2011 three March 31, 2021 three March 31, 2020, Three Months Ended March 31, 2020 Expected life (in years) 4.45 Volatility 38.77 % Risk-free interest rate 0.88 % Expected dividend — Weighted average fair value per share of options granted during the period $ 5.21 Stock-Based Compensation Stock-based compensation is estimated at the grant date based on the award’s fair value and is recognized on a straight-line basis over the vesting periods, generally four . Three Months Ended March 31, 2021 2020 Costs of revenues $ 652 $ 909 Research and development 1,588 1,455 Selling, general and administrative 1,129 1,004 Stock-based compensation expenses (1) $ 3,369 $ 3,368 ____________________ ( 1 The stock-based compensation expense during the three March 31, 2020 third 2020. Stock-based compensation expense that was recorded as capitalized software development costs under property and equipment, net, was nil three March 31, 2021 2020 Additional information with respect to options under the Stock Plans during the three March 31, 2021 Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Options Price per Term Value (in thousands) Share (years) (in thousands) Outstanding, January 1, 2021 456 $ 10.95 Granted — — Exercised (81 ) 6.97 Canceled — — Expired — — Outstanding, March 31, 2021 375 $ 11.81 3.41 $ 2,309 Vested and expected to vest, March 31, 2021 369 $ 11.76 3.33 $ 2,293 Exercisable, March 31, 2021 307 $ 11.14 2.30 $ 2,104 The aggregate intrinsic value in the table above represents the total intrinsic value based on the Company’s closing stock price of $17.78 per share as of March 31, 2021 three March 31, 2021 As of March 31, 2021 three March 31, 2021 Non-vested restricted stock unit activity during the three March 31, 2021 Weighted Average Grant Shares Date Fair Value (in thousands) Per Share Non-vested, January 1, 2021 1,747 $ 16.33 Granted 141 $ 19.84 Vested (223 ) $ 17.32 Forfeited (23 ) $ 15.88 Non-vested, March 31, 2021 1,642 $ 16.51 As of March 31, 2021 not

Note 9 - Income Taxes

Note 9 - Income Taxes	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Income Tax Disclosure [Text Block]	9. Income tax benefit decreased $4.4 million for the three March 31, 2021 three March 31, 2020 three March 31, 2021 2020 three March 31, 2021 2020 one first 2020 March 27, 2020. The Company’s total amount of unrecognized tax benefits, excluding interest and penalties, as of March 31, 2021 December 31, 2020 March 31, 2021 The valuation allowance was approximately $41.9 million as of March 31, 2021 December 31, 2020 The Company conducts business globally and, as a result, files numerous consolidated and separate income tax returns in the U.S. federal, various state and foreign jurisdictions. For U.S. federal and California income tax purposes, the statute of limitations currently remains open for the tax years ending 2017 2016 2013 2015 may may may not On March 11, 2021, 2021 19 740, March 11, 2021. not

Note 10 - Net Loss Per Share

Note 10 - Net Loss Per Share	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Earnings Per Share [Text Block]	10 . NET LOSS PER SHARE Basic net loss per share is computed by dividing net loss by weighted average number of common shares outstanding for the period (excluding outstanding stock options and shares subject to repurchase). Diluted net loss per share is computed using the weighted-average number of common shares outstanding for the period plus the potential effect of dilutive securities which are convertible into common shares (using the treasury stock method), except in cases in which the effect would be anti-dilutive. The following is a reconciliation of the numerators and denominators used in computing basic and diluted net loss per share (in thousands except per share amount): Three Months Ended March 31, 2021 2020 Numerator: Net loss $ (7,597 ) $ (528 ) Denominator: Basic weighted-average shares outstanding 36,974 32,703 Effect of dilutive options and restricted stock units — — Diluted weighted-average shares outstanding 36,974 32,703 Net loss per share, basic and diluted $ (0.21 ) $ (0.02 ) For the three March 31, 2021 2020 The following table sets forth potential shares of common stock that were not Three Months Ended March 31, 2021 2020 Outstanding options 224 400 Non-vested restricted stock units 1,107 716 Employee Stock Purchase Plan 10 100 Total 1,341 1,216

Note 11 - Customer and Geograph

Note 11 - Customer and Geographic Information	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	11 . CUSTOMER AND GEOGRAPHIC INFORMATION Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or group, in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker, the chief executive officer, reviews discrete financial information presented on a consolidated basis for purposes of regularly making operating decisions, allocation of resources, and assessing financial performance. Accordingly, the Company considers itself to be in one The Company had revenues from individual customers in excess of 10% Three Months Ended March 31, Customer 2021 2020 A 13 % 26 % B 11 % * % __________________________ * represents less than 10% The Company had gross accounts receivable from individual customers in excess of 10% March 31, December 31, Customer 2021 2020 A * % 16 % B 11 % 11 % __________________________ * represents less than 10% Revenues from customers by geographic area based on the location of the customers’ work sites are as follows (amounts in thousands): Three Months Ended March 31, 2021 2020 Percentage Percentage Revenues of Revenues Revenues of Revenues United States $ 8,556 35 % $ 8,617 41 % Japan 3,578 15 1,207 6 Taiwan 2,052 8 2,668 12 China 1,739 7 2,959 14 Rest of the world 8,275 35 5,707 27 Total revenue $ 24,200 100 % $ 21,158 100 % Long-lived assets, net by geographic area are as follows (in thousands): March 31, December 31, 2021 2020 United States $ 42,417 $ 43,663 Rest of the world 1,901 2,251 Total long-lived assets, net $ 44,318 $ 45,914

Note 12 - Fair Value Measuremen

Note 12 - Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Fair Value Disclosures [Text Block]	12 . FAIR VALUE MEASUREMENTS Fair value is the exit price, or the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants as of the measurement date. The multiple assumptions used to value financial instruments are referred to as inputs, and a hierarchy for inputs used in measuring fair value is established, that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs reflect assumptions market participants would use in pricing an asset or liability based on market data obtained from independent sources while unobservable inputs reflect a reporting entity’s pricing based upon its own market assumptions. These inputs are ranked according to a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three Level 1 Inputs are quoted prices in active markets for identical assets or liabilities. Level 2 Inputs are quoted prices for similar assets or liabilities in an active market, quoted prices for identical or similar assets or liabilities in markets that are not Level 3 Inputs are derived from valuation techniques in which one The following table represents the Company’s assets measured at fair value on a recurring basis as of March 31, 2021 December 31, 2020 Fair Value Measurements Using Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable March 31, Assets Inputs Inputs Assets 2021 (Level 1) (Level 2) (Level 3) Cash equivalents Money market mutual funds $ 63,017 $ 63,017 $ — $ — Short-term investments (available-for-sale debt securities) U.S. Treasury bills 57,999 57,999 — — Total $ 121,016 $ 121,016 $ — $ — Fair Value Measurements Using Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs Assets 2020 (Level 1) (Level 2) (Level 3) Cash equivalents Money market mutual funds $ 18,012 $ 18,012 $ — $ — Short-term investments (available-for-sale debt securities) U.S. Treasury bills 114,981 114,981 — — Total $ 132,993 $ 132,993 $ — $ — As of March 31, 2021 December 31, 2020, no no From time to time, the Company enters into foreign currency forward contracts to reduce the exposure to foreign currency exchange rate fluctuations on certain foreign currency denominated monetary assets and liabilities, primarily on third not not Therefore, the change in fair value of these contracts is recorded into earnings as a component of other expense (income), net, and offsets the change in fair value of the foreign currency denominated assets and liabilities, which is also recorded in other expense (income), net in the Company’s Condensed Consolidated Statements of Comprehensive Loss. For the three March 31, 2021 three March 31, 2020 The Company carries these derivatives financial instruments on its Condensed Consolidated Balance Sheets at their fair values. The Company’s foreign currency forward contracts are classified as Level 2 not March 31, 2021 December 31, 2020 no

Note 13 - Commitments and Conti

Note 13 - Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	13 . COMMITMENTS AND CONTINGENCIES Strategic Partnership with Advantest 4, Business Combination Operating Leases 6, Leases Indemnifications 90 third not Purchase Obligations March 31, 2021 24 Indemnification of Officers and Directors In addition, the Bylaws of the Company provide that the Company is required to indemnify its officers and directors even when indemnification would otherwise be discretionary, and the Company is required to advance expenses to its officers and directors as incurred in connection with proceedings against them for which they may may not Legal Proceedings March 31, 2021 not no no On May 6, 2020,

Significant Accounting Policies

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The interim unaudited condensed consolidated financial statements included herein have been prepared by PDF Solutions, Inc. (the “Company”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”), including the instructions to the Quarterly Report on Form 10 10 X. not may 10 December 31, 2020 The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries after the elimination of all intercompany balances and transactions. The condensed consolidated balance sheet at December 31, 2020 not
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (“U.S. 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. Significant estimates in these financial statements include revenue recognition, assumptions made in analysis of allowance for doubtful accounts, impairment of goodwill and long-lived assets, realization of deferred tax assets (DTAs), and accounting for lease obligations, stock-based compensation expense, and income taxes. Actual results could differ from those estimates. The global COVID- 19 may 2020 first 2021 may 2020 2021. may 19 may 19 not may may
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Standards Accounting Standards Adopted In December 2019, No. 2019 12, 740 740 first 2021 January 1, 2021, not In January 2020, No. 2020 01 321 323 815 321, 323, 815. 321 323 815 December 15, 2020. January 1, 2021, not Accounting Standards Not In June 2016, No. 2016 13, 326 2016 13 No. 2016 13 No. 2016 13, No. 2018 19, 326, No. 2019 04, 326, 815, 825, No. 2019 05, 326 No. 2016 13, No. 2019 10 326 815 842 No. 2019 11 326, not No. 2016 13. No. 2016 13. Additionally, ASU No. 2019 10 December 15, 2022, 2023 February 2020, 2020 02, No. 2016 13. 326 326, not In August 2020, No. 2020 06, 470 20 815 20 December 15, 2023 not Management has reviewed other recently issued accounting pronouncements issued or proposed by the FASB, and does not

Note 2 - Revenue From Contrac_2

Note 2 - Revenue From Contracts With Customers (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Disaggregation of Revenue [Table Text Block]	Three Months Ended March 31, 2021 2020 Over time 50 % 58 % Point-in-time 50 % 42 % Total 100 % 100 %

Note 4 - Business Combination (

Note 4 - Business Combination (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	Amount Amortization Period (Years) Assets Fair value of tangible assets (including cash of $5,900) $ 8,403 Fair value of intangible assets: Developed technology 12,541 8 In-process R&D 3,635 N/A Customer relationships 1,967 10 Noncompetition agreements 848 3 Tradenames and trademarks 808 10 Goodwill 13,012 N/A Total assets acquired $ 41,214 Liabilities Accounts payable and accrued expenses $ 1,437 Deferred revenue 391 Operating lease liabilities 132 Deferred tax liabilities 1,743 Total liabilities assumed $ 3,703 Total purchase price allocation $ 37,511

Note 5 - Balance Sheet Compon_2

Note 5 - Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Property, Plant and Equipment [Table Text Block]	March 31, December 31, 2021 2020 Computer equipment $ 11,595 $ 11,585 Software 5,435 5,451 Furniture, fixtures and equipment 2,501 2,507 Leasehold improvements 6,255 6,255 Laboratory and other equipment 3,571 3,451 Test equipment 25,977 26,010 Construction-in-progress 20,699 20,278 76,033 75,537 Less: accumulated depreciation and amortization (37,886 ) (36,295 ) Total $ 38,147 $ 39,242
Schedule of Goodwill [Table Text Block]	March 31, 2021 Balance at beginning of period $ 15,774 Measurement period acquisition adjustment (1) (469 ) Balance at end of period $ 15,305
Schedule of Finite-Lived Intangible Assets [Table Text Block]	March 31, 2021 December 31, 2020 Amortization Gross Net Gross Net Period Carrying Accumulated Carrying Carrying Accumulated Carrying (Years) Amount Amortization Amount Amount Amortization Amount Acquired identifiable intangibles: Customer relationships 1 ‒ 10 $ 9,407 $ (5,558 ) $ 3,849 $ 9,407 $ (5,398 ) $ 4,009 Developed technology 4 ‒ 9 30,000 (15,570 ) 14,430 30,000 (14,987 ) 15,013 Tradename and trademarks 2 ‒ 10 1,598 (732 ) 866 1,598 (706 ) 892 Patent 7 ‒ 10 1,800 (1,610 ) 190 1,800 (1,600 ) 200 Noncompetition agreements 3 848 (94 ) 754 848 (24 ) 824 In-process R&D * 3,635 — 3,635 3,635 — 3,635 Total $ 47,288 $ (23,564 ) $ 23,724 $ 47,288 $ (22,715 ) $ 24,573
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Year Ending December 31, Amount 2021 (remaining nine months) $ 2,372 2022 3,013 2023 2,990 2024 2,592 2025 2,427 2026 and thereafter 6,695 Total future amortization expense $ 20,089

Note 6 - Leases (Tables)

Note 6 - Leases (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Lease, Cost [Table Text Block]	Three Months Ended March 31, 2021 2020 Operating lease expense $ 485 $ 455 Short-term lease and variable lease expense (1) 174 147 Total lease expense $ 659 $ 602 March 31, December 31, 2021 2020 Weighted average remaining lease term under operating ROU leases (in years) 6.3 6.4 Weighted average discount rate for operating lease liabilities 5.24 % 5.24 % Operating lease ROU assets obtained (in thousands) $ — $ 286
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Year Ending December 31, Amount (1) 2021 (remaining nine months) $ 1,453 2022 1,699 2023 1,385 2024 1,074 2025 1,089 2026 and thereafter 2,703 Total future minimum lease payments $ 9,403 Less: Interest (2) (1,510 ) Present value of future minimum lease payments under operating lease liabilities (3) $ 7,893

Note 8 - Employee Benefit Pla_2

Note 8 - Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	Three Months Ended March 31, 2021 2020 Expected life (in years) 1.25 1.25 Volatility 34.25 % 34.25 % Risk-free interest rate 1.43 % 1.43 % Expected dividend — — Weighted average fair value of purchase rights granted during the period $ 4.83 $ 4.83 Three Months Ended March 31, 2020 Expected life (in years) 4.45 Volatility 38.77 % Risk-free interest rate 0.88 % Expected dividend — Weighted average fair value per share of options granted during the period $ 5.21
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Three Months Ended March 31, 2021 2020 Costs of revenues $ 652 $ 909 Research and development 1,588 1,455 Selling, general and administrative 1,129 1,004 Stock-based compensation expenses (1) $ 3,369 $ 3,368
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Options Price per Term Value (in thousands) Share (years) (in thousands) Outstanding, January 1, 2021 456 $ 10.95 Granted — — Exercised (81 ) 6.97 Canceled — — Expired — — Outstanding, March 31, 2021 375 $ 11.81 3.41 $ 2,309 Vested and expected to vest, March 31, 2021 369 $ 11.76 3.33 $ 2,293 Exercisable, March 31, 2021 307 $ 11.14 2.30 $ 2,104
Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]	Weighted Average Grant Shares Date Fair Value (in thousands) Per Share Non-vested, January 1, 2021 1,747 $ 16.33 Granted 141 $ 19.84 Vested (223 ) $ 17.32 Forfeited (23 ) $ 15.88 Non-vested, March 31, 2021 1,642 $ 16.51

Note 10 - Net Loss Per Share (T

Note 10 - Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended March 31, 2021 2020 Numerator: Net loss $ (7,597 ) $ (528 ) Denominator: Basic weighted-average shares outstanding 36,974 32,703 Effect of dilutive options and restricted stock units — — Diluted weighted-average shares outstanding 36,974 32,703 Net loss per share, basic and diluted $ (0.21 ) $ (0.02 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three Months Ended March 31, 2021 2020 Outstanding options 224 400 Non-vested restricted stock units 1,107 716 Employee Stock Purchase Plan 10 100 Total 1,341 1,216

Note 11 - Customer and Geogra_2

Note 11 - Customer and Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	Three Months Ended March 31, Customer 2021 2020 A 13 % 26 % B 11 % * % March 31, December 31, Customer 2021 2020 A * % 16 % B 11 % 11 %
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	Three Months Ended March 31, 2021 2020 Percentage Percentage Revenues of Revenues Revenues of Revenues United States $ 8,556 35 % $ 8,617 41 % Japan 3,578 15 1,207 6 Taiwan 2,052 8 2,668 12 China 1,739 7 2,959 14 Rest of the world 8,275 35 5,707 27 Total revenue $ 24,200 100 % $ 21,158 100 %
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]	March 31, December 31, 2021 2020 United States $ 42,417 $ 43,663 Rest of the world 1,901 2,251 Total long-lived assets, net $ 44,318 $ 45,914

Note 12 - Fair Value Measurem_2

Note 12 - Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Notes Tables
Fair Value, Assets Measured on Recurring Basis [Table Text Block]	Fair Value Measurements Using Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable March 31, Assets Inputs Inputs Assets 2021 (Level 1) (Level 2) (Level 3) Cash equivalents Money market mutual funds $ 63,017 $ 63,017 $ — $ — Short-term investments (available-for-sale debt securities) U.S. Treasury bills 57,999 57,999 — — Total $ 121,016 $ 121,016 $ — $ — Fair Value Measurements Using Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs Assets 2020 (Level 1) (Level 2) (Level 3) Cash equivalents Money market mutual funds $ 18,012 $ 18,012 $ — $ — Short-term investments (available-for-sale debt securities) U.S. Treasury bills 114,981 114,981 — — Total $ 132,993 $ 132,993 $ — $ —

Note 2 - Revenue From Contrac_3

Note 2 - Revenue From Contracts With Customers 1 (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Capitalized Contract Cost, Impairment Loss	$ 0	$ 0
Contract with Customer, Liability, Noncurrent	1,600		$ 1,200
Contract with Customer, Liability, Revenue Recognized	6,300	4,600
Revenue, Remaining Performance Obligation, Amount	114,200
Contract with Customer, Performance Obligation Satisfied in Previous Period	300	700
Capitalized Contract Cost, Amortization	165	$ 124
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Current, Total	400		3,700
Capitalized Contract Cost, Net, Total	800		800
Other Noncurrent Assets [Member]
Capitalized Contract Cost, Net, Total	$ 1,100		$ 900
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	100.00%	100.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Non-US [Member]
Concentration Risk, Percentage	65.00%	59.00%

Note 2 - Revenue From Contrac_4

Note 2 - Revenue From Contracts With Customers 2 (Details Textual) - Software License and Related Services Agreement [Member] - Advantest America, Inc. [Member]	Mar. 31, 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year)	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period (Year)	3 years

Note 2 - Revenue From Contrac_5

Note 2 - Revenue From Contracts With Customers - Disaggregation of Revenue (Details)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Percent of revenues	100.00%	100.00%
Transferred over Time [Member]
Percent of revenues	50.00%	58.00%
Transferred at Point in Time [Member]
Percent of revenues	50.00%	42.00%

Note 3 - Strategic Partnershi_2

Note 3 - Strategic Partnership Agreement With Advantest and Related Party Transactions (Details Textual) - USD ($) $ in Thousands	Jul. 29, 2020	Mar. 31, 2021	Mar. 31, 2020
Revenue from Contract with Customer, Including Assessed Tax		$ 24,200	$ 21,158
Strategic Partnership for Joint Development and Sales Technology Solutions [Member]
Stock Issued During Period, Shares, New Issues (in shares)	3,306,924
Proceeds from Issuance of Common Stock	$ 65,200
Amendment #1 to Software License & Related Services Agreement [Member]
Revenue from Contract with Customer, Including Assessed Tax		2,600
Related Party Transaction, Due from (to) Related Party, Total		100
Contract with Customer, Liability, Total		2,200
Commercial Agreement With Advantest [Member]
Costs and Expenses, Related Party		$ 0

Note 4 - Business Combination_2

Note 4 - Business Combination (Details Textual) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Dec. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restricted Cash, Total		$ 3,019	$ 0
Cimetrix Incorporated [Member]
Payments to Acquire Businesses, Net of Cash Acquired, Total	$ 28,600
Business Combination, Holdback Amount	3,500	3,000
Goodwill, Period Increase (Decrease), Total		(500)
Business Combination, Estimated Cash Payout to Certain Employees	1,400
Business Combination, Estimated Remaining Cash Payout to Certain Employees		1,000
Business Combination, Acquisition Related Costs	1,600
Cimetrix Incorporated [Member] | Prepaid Expenses and Other Current Assets [Member]
Restricted Cash, Total	3,500	3,000
Cimetrix Incorporated [Member] | Accrued Compensation and Related Benefits [Member]
Business Combination, Accrued Estimated Cash Payout to Certain Employees	$ 300	$ 200

Note 4 - Business Combination -

Note 4 - Business Combination - Fair Values of Assets Acquired and Liabilities Assumed and the Related Useful Lives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Goodwill	$ 15,305	$ 15,774
Cimetrix Incorporated [Member]
Fair value of tangible assets (including cash of $5,900)	8,403
Goodwill	13,012
Total assets acquired	41,214
Accounts payable and accrued expenses	1,437
Deferred revenue	391
Operating lease liabilities	132
Deferred tax liabilities	1,743
Total liabilities assumed	3,703
Total purchase price allocation	37,511
Cimetrix Incorporated [Member] | In Process Research and Development [Member]
Fair value of indefinite-lived intangible assets	3,635
Developed Technology Rights [Member] | Cimetrix Incorporated [Member]
Fair value of cash	5,900
Fair value of finite-lived intangible assets	$ 12,541
Finite-lived intangible assets, amortization period (Year)	8 years
Customer Relationships [Member] | Cimetrix Incorporated [Member]
Fair value of finite-lived intangible assets	$ 1,967
Finite-lived intangible assets, amortization period (Year)	10 years
Noncompete Agreements [Member] | Cimetrix Incorporated [Member]
Fair value of finite-lived intangible assets	$ 848
Finite-lived intangible assets, amortization period (Year)	3 years
Trademarks and Trade Names [Member] | Cimetrix Incorporated [Member]
Fair value of finite-lived intangible assets	$ 808
Finite-lived intangible assets, amortization period (Year)	10 years

Note 4 - Business Combination_3

Note 4 - Business Combination - Fair Values of Assets Acquired and Liabilities Assumed and the Related Useful Lives (Details) (Parentheticals) $ in Millions	Mar. 31, 2021USD ($)
Developed Technology Rights [Member] | Cimetrix Incorporated [Member]
Fair value of cash	$ 5.9

Note 5 - Balance Sheet Compon_3

Note 5 - Balance Sheet Components (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Unbilled Receivables, Current	$ 10,500		$ 7,200
Unbilled Receivables, Not Expected to be Billed and Collected in Next Twelve Months	1,800		2,000
Depreciation, Depletion and Amortization, Nonproduction, Total	1,700	$ 1,700
Impairment of Intangible Assets, Finite-lived	$ 0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	6 years 1 month 6 days
Amortization of Intangible Assets, Total	$ 800	$ 300
DFI Test Equipment [Member]
Construction in Progress, Gross	$ 19,300		$ 18,900

Note 5 - Balance Sheet Compon_4

Note 5 - Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property and equipment, gross	$ 76,033	$ 75,537
Less: accumulated depreciation and amortization	(37,886)	(36,295)
Total	38,147	39,242
Computer Equipment [Member]
Property and equipment, gross	11,595	11,585
Software and Software Development Costs [Member]
Property and equipment, gross	5,435	5,451
Furniture and Fixtures [Member]
Property and equipment, gross	2,501	2,507
Leasehold Improvements [Member]
Property and equipment, gross	6,255	6,255
Laboratory and Test Equipment [Member]
Property and equipment, gross	3,571	3,451
Test Equipment [Member]
Property and equipment, gross	25,977	26,010
Construction in Progress [Member]
Property and equipment, gross	$ 20,699	$ 20,278

Note 5 - Balance Sheet Compon_5

Note 5 - Balance Sheet Components - Change in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021		Mar. 31, 2020
Balance at beginning of period	$ 15,774
Measurement period acquisition adjustment (1)	(469)	[1]	$ 0
Balance at end of period	$ 15,305
[1]	Goodwill adjustment was recorded within the measurement period with a corresponding reduction in the Holdback Amount. See Note 4, Business Combination.

Note 5 - Balance Sheet Compon_6

Note 5 - Balance Sheet Components - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Amortization Period (Year)	6 years 1 month 6 days
Accumulated Amortization	$ (23,564)	$ (22,715)
Net Carrying Amount	20,089
Gross Carrying Amount, Total	47,288	47,288
Net Carrying Amount, Total	23,724	24,573
In Process Research and Development [Member]
In-process R&D	3,635	3,635
Customer Relationships [Member]
Gross Carrying Amount	9,407	9,407
Accumulated Amortization	(5,558)	(5,398)
Net Carrying Amount	$ 3,849	4,009
Customer Relationships [Member] | Minimum [Member]
Amortization Period (Year)	1 year
Customer Relationships [Member] | Maximum [Member]
Amortization Period (Year)	10 years
Developed Technology Rights [Member]
Gross Carrying Amount	$ 30,000	30,000
Accumulated Amortization	(15,570)	(14,987)
Net Carrying Amount	$ 14,430	15,013
Developed Technology Rights [Member] | Minimum [Member]
Amortization Period (Year)	4 years
Developed Technology Rights [Member] | Maximum [Member]
Amortization Period (Year)	9 years
Trademarks and Trade Names [Member]
Gross Carrying Amount	$ 1,598	1,598
Accumulated Amortization	(732)	(706)
Net Carrying Amount	$ 866	892
Trademarks and Trade Names [Member] | Minimum [Member]
Amortization Period (Year)	2 years
Trademarks and Trade Names [Member] | Maximum [Member]
Amortization Period (Year)	10 years
Patents [Member]
Gross Carrying Amount	$ 1,800	1,800
Accumulated Amortization	(1,610)	(1,600)
Net Carrying Amount	$ 190	200
Patents [Member] | Minimum [Member]
Amortization Period (Year)	7 years
Patents [Member] | Maximum [Member]
Amortization Period (Year)	10 years
Noncompete Agreements [Member]
Amortization Period (Year)	3 years
Gross Carrying Amount	$ 848	848
Accumulated Amortization	(94)	(24)
Net Carrying Amount	$ 754	$ 824

Note 5 - Balance Sheet Compon_7

Note 5 - Balance Sheet Components - Annual Amortization of Identifiable Intangible Assets (Details) $ in Thousands	Mar. 31, 2021USD ($)
2021 (remaining nine months)	$ 2,372
2022	3,013
2023	2,990
2024	2,592
2025	2,427
2026 and thereafter	6,695
Total future amortization expense	$ 20,089

Note 6 - Leases (Details Textua

Note 6 - Leases (Details Textual) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Operating Lease, Liability, Amount Related to Extension of Lease Term	$ 1,100
Operating Lease, Liability, Current	$ 1,742	$ 1,926

Note 6 - Leases - Lease Cost (D

Note 6 - Leases - Lease Cost (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Operating lease expense		$ 485	$ 455
Short-term lease and variable lease expense (1)	[1]	174	147
Total lease expense		$ 659	$ 602
Weighted average remaining lease term under operating ROU leases (in years) (Year)		6 years 3 months 18 days		6 years 4 months 24 days
Weighted average discount rate for operating lease liabilities		5.24%		5.24%
Operating lease ROU assets obtained (in thousands)		$ 0		$ 286
[1]	Leases with an initial term of 12 months or less are not recorded on the balance sheets, and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. Variable lease expense for the periods presented primarily included common area maintenance charges.

Note 6 - Leases - Maturity of O

Note 6 - Leases - Maturity of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2021USD ($)	[1]
2021 (remaining nine months)	$ 1,453
2022	1,699
2023	1,385
2024	1,074
2025	1,089
2026 and thereafter	2,703
Total future minimum lease payments	9,403
Less: Interest (2)	(1,510)	[2]
Present value of future minimum lease payments under operating lease liabilities (3)	$ 7,893	[3]
[1]	As of March 31, 2021, the total operating lease liability includes approximately $1.1 million related to an option to extend a lease term that is reasonably certain to be exercised.
[2]	Calculated using incremental borrowing interest rate for each lease.
[3]	Includes the current portion of operating lease liabilities of $1.7 million as of March 31, 2021.

Note 7 - Stockholders' Equity (

Note 7 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Jul. 30, 2020	Jun. 04, 2020	Mar. 31, 2021	May 28, 2020
Treasury Stock, Value, Acquired, Cost Method			$ 4,523
The 2018 Stock Repurchase Program [Member]
Treasury Stock, Shares, Acquired (in shares)				786,000
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)				$ 12.43
Treasury Stock, Value, Acquired, Cost Method				$ 9,800
The 2020 Stock Repurchase Program [Member]
Treasury Stock, Shares, Acquired (in shares)			251,212
Treasury Stock Acquired, Average Cost Per Share (in dollars per share)			$ 18.01
Treasury Stock, Value, Acquired, Cost Method			$ 4,500
Stock Repurchase Program, Authorized Amount		$ 25,000
Stock Repurchase Program, Period in Force (Year)		2 years
Strategic Partnership for Joint Development and Sales Technology Solutions [Member]
Stock Issued During Period, Shares, New Issues (in shares)	3,306,924
Shares Issued, Price Per Share (in dollars per share)	$ 19.7085
Proceeds from Issuance of Common Stock	$ 65,200
Payments of Stock Issuance Costs	$ 100

Note 8 - Employee Benefit Pla_3

Note 8 - Employee Benefit Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Nov. 16, 2011	Jul. 31, 2001	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2001	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (in shares)			0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)			375,000			456,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)			0
Share-based Payment Arrangement, Amount Capitalized			$ 0	$ 128
Share Price (in dollars per share)			$ 17.78
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value			$ 1,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value			39
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			$ 300
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			2 years 4 months 24 days
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			$ 21,200
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			2 years 4 months 24 days
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate		10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent		85.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)			99,674	89,000
Employee Stock Purchase Plan Weighted Average Purchase Price of Shares Purchased (in dollars per share)			$ 9.24	$ 9.02
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total			$ 100
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			8 months 12 days
Twenty Eleven Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)	11,550,000
Share Based Compensation Arrangement By Share Based Payment Award Shares Reserved Decrease Rate (in shares)	1.33
Common Stock, Capital Shares Reserved for Future Issuance (in shares)			12,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)			4,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period (in shares)			500,000
Twenty Eleven Stock Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)	4 years
Shares Previously Issued Under the 2001 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)					3,500,000
IDS Plan [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)					10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)					4 years
Outside of the 2011, 2001 or IDS Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance (in shares)			0

Note 8 - Employee Benefit Pla_4

Note 8 - Employee Benefit Plans - Stock Options, Valuation Assumptions (Details) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Twenty Eleven Stock Incentive Plan [Member]
Expected life (Year)		4 years 5 months 12 days
Volatility		38.77%
Risk-free interest rate		0.88%
Expected dividend		0.00%
Weighted average fair value per share of options granted during the period (in dollars per share)		$ 5.21
Employee Stock Purchase Plan [Member]
Expected life (in years) (Year)	1 year 3 months	1 year 3 months
Volatility	34.25%	34.25%
Risk-free interest rate	1.43%	1.43%
Expected dividend	0.00%	0.00%
Weighted average fair value of purchase rights granted during the period (in dollars per share)	$ 4.83	$ 4.83

Note 8 - Employee Benefit Pla_5

Note 8 - Employee Benefit Plans - Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Stock-based compensation expenses	[1]	$ 3,369	$ 3,368
Cost of Sales [Member]
Stock-based compensation expenses		652	909
Research and Development Expense [Member]
Stock-based compensation expenses		1,588	1,455
Selling, General and Administrative Expenses [Member]
Stock-based compensation expenses		$ 1,129	$ 1,004
[1]	The stock-based compensation expense during the three months ended March 31, 2020 includes immaterial expense or credit adjustments related to cash-settled SARs granted to certain employees. The Company accounted for these awards as liability awards and the amount was included in accrued compensation and related benefits. All remaining outstanding SARs were fully exercised in the third quarter of 2020.

Note 8 - Employee Benefit Pla_6

Note 8 - Employee Benefit Plans - Stock Options Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)$ / sharesshares
Outstanding, beginning balance (in shares) | shares	456
Outstanding, weighted average exercise price, beginning balance (in dollars per share) | $ / shares	$ 10.95
Granted (in shares) | shares	0
Granted, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Exercised (in shares) | shares	(81)
Exercised, weighted average exercise price (in dollars per share) | $ / shares	$ 6.97
Canceled (in shares) | shares	0
Canceled, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Expired (in shares) | shares	0
Expired, weighted average exercise price (in dollars per share) | $ / shares	$ 0
Outstanding, ending balance (in shares) | shares	375
Outstanding, weighted average exercise price, ending balance (in dollars per share) | $ / shares	$ 11.81
Outstanding, weighted average remaining contractual (Year)	3 years 4 months 28 days
Outstanding, aggregate intrinsic value | $	$ 2,309
Vested and expected to vest (in shares) | shares	369
Vested and expected to vest, weighted average exercise price (in dollars per share) | $ / shares	$ 11.76
Vested and expected to vest, weighted average remaining contractual term (Year)	3 years 3 months 29 days
Vested and expected to vest, aggregate intrinsic value | $	$ 2,293
Exercisable (in shares) | shares	307
Exercisable, weighted average exercise price (in dollars per share) | $ / shares	$ 11.14
Exercisable, weighted average remaining contractual term (Year)	2 years 3 months 18 days
Exercisable, aggregate intrinsic value | $	$ 2,104

Note 8 - Employee Benefit Pla_7

Note 8 - Employee Benefit Plans - Nonvested Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs) [Member] shares in Thousands	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Nonvested, Balance (in shares) | shares	1,747
Nonvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 16.33
Granted (in shares) | shares	141
Granted, weighted average grant date fair value (in dollars per share) | $ / shares	$ 19.84
Vested (in shares) | shares	(223)
Vested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 17.32
Forfeited (in shares) | shares	(23)
Forfeited, weighted average grant date fair value (in dollars per share) | $ / shares	$ 15.88
Nonvested, Balance (in shares) | shares	1,642
Nonvested, weighted average grant date fair value (in dollars per share) | $ / shares	$ 16.51

Note 9 - Income Taxes (Details

Note 9 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Increase (Decrease) in Income Taxes	$ (4,400)
Income Tax Expense (Benefit), Total	$ 956	$ (3,479)
Effective Income Tax Rate Reconciliation, Percent, Total	14.00%	86.00%
Unrecognized Tax Benefits, Ending Balance	$ 14,500		$ 14,300
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 2,200	2,200
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	3,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued in Long Term Liabilities	800
Unrecognized Tax Benefits In Deferred Tax Assets	12,300
Deferred Tax Assets, Valuation Allowance, Total	$ 41,900		$ 41,900

Note 10 - Net Loss Per Share -

Note 10 - Net Loss Per Share - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net loss	$ (7,597)	$ (528)
Basic weighted-average shares outstanding (in shares)	36,974	32,703
Effect of dilutive options and restricted stock units (in shares)	0	0
Diluted weighted-average shares outstanding (in shares)	36,974	32,703
Net loss per share, basic and diluted (in dollars per share)	$ (0.21)	$ (0.02)

Note 10 - Net Loss Per Share _2

Note 10 - Net Loss Per Share - Anti-dilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Anti-dilutive securities (in shares)	1,341	1,216
Share-based Payment Arrangement, Option [Member]
Anti-dilutive securities (in shares)	224	400
Restricted Stock Units (RSUs) [Member]
Anti-dilutive securities (in shares)	1,107	716
Employee Stock Purchase Plan [Member]
Anti-dilutive securities (in shares)	10	100

Note 11 - Customer and Geogra_3

Note 11 - Customer and Geographic Information (Details Textual)	3 Months Ended
	Mar. 31, 2021
Number of Operating Segments	1
Number of Reportable Segments	1

Note 11 - Customer and Geogra_4

Note 11 - Customer and Geographic Information - Revenue Percentage by Major Customers (Details) - Customer Concentration Risk [Member]	3 Months Ended			12 Months Ended
	Mar. 31, 2021		Mar. 31, 2020	Dec. 31, 2020
Revenue Benchmark [Member] | Customer A [Member]
Concentration risk	13.00%		26.00%
Revenue Benchmark [Member] | Customer B [Member]
Concentration risk	11.00%
Accounts Receivable [Member] | Customer A [Member]
Concentration risk				16.00%
Accounts Receivable [Member] | Customer B [Member]
Concentration risk	11.00%	[1]		11.00%
[1]	represents less than 10%

Note 11 - Customer and Geogra_5

Note 11 - Customer and Geographic Information - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues	$ 24,200	$ 21,158
Geographic Concentration Risk [Member] | Revenue Benchmark [Member]
Revenues	$ 24,200	$ 21,158
Concentration risk	100.00%	100.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED STATES
Revenues	$ 8,556	$ 8,617
Concentration risk	35.00%	41.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | JAPAN
Revenues	$ 3,578	$ 1,207
Concentration risk	15.00%	6.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | TAIWAN, PROVINCE OF CHINA
Revenues	$ 2,052	$ 2,668
Concentration risk	8.00%	12.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | CHINA
Revenues	$ 1,739	$ 2,959
Concentration risk	7.00%	14.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Rest of the World [Member]
Revenues	$ 8,275	$ 5,707
Concentration risk	35.00%	27.00%

Note 11 - Customer and Geogra_6

Note 11 - Customer and Geographic Information - Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Long-lived assets, net	$ 44,318	$ 45,914
UNITED STATES
Long-lived assets, net	42,417	43,663
Rest of the World [Member]
Long-lived assets, net	$ 1,901	$ 2,251

Note 12 - Fair Value Measurem_3

Note 12 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Foreign Exchange Contract [Member] | Other Nonoperating Income (Expense) [Member]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 0	$ (300)

Note 12 - Fair Value Measurem_4

Note 12 - Fair Value Measurements - Fair Value, Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Total	$ 121,016	$ 132,993
Fair Value, Inputs, Level 1 [Member]
Total	121,016	132,993
Fair Value, Inputs, Level 2 [Member]
Total	0	0
Fair Value, Inputs, Level 3 [Member]
Total	0	0
Money Market Funds [Member]
Money market mutual funds	63,017	18,012
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Money market mutual funds	63,017	18,012
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Money market mutual funds	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Money market mutual funds	0	0
US Treasury Securities [Member]
U.S. Treasury bills	57,999	114,981
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
U.S. Treasury bills	57,999	114,981
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
U.S. Treasury bills	0	0
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
U.S. Treasury bills	$ 0	$ 0

Note 13 - Commitments and Con_2

Note 13 - Commitments and Contingencies (Details Textual) $ in Millions	Mar. 31, 2021USD ($)
Purchase Obligation, Total	$ 10.6