Power Integrations (POWI) 10-K 7 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ / shares in Units, $ in Billions	12 Months Ended
	Dec. 31, 2021	Feb. 01, 2022	Jun. 30, 2021
Document and Entity Information
Title of 12(b) Security	Common Stock
Entity Address, Address Line One	5245 Hellyer Avenue
Entity Incorporation, State or Country Code	DE
Entity Registrant Name	POWER INTEGRATIONS, INC.
Entity Central Index Key	0000833640
Current Fiscal Year End Date	--12-31
Trading Symbol	POWI
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	000-23441
Document Fiscal Year Focus	2021
Amendment Flag	false
Document Fiscal Period Focus	FY
Entity Listing, Par Value Per Share	$ 0.001
Entity Common Stock, Shares Outstanding		59,158,747
Auditor Name	DELOITTE & TOUCHE LLP
Auditor Firm ID	34
Auditor Location	San Jose, California
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 3.6
Entity Tax Identification Number	94-3065014
City Area Code	408
Local Phone Number	414-9200
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95138-1002
Security Exchange Name	NASDAQ

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 158,117	$ 258,874
Short-term marketable securities	372,235	190,318
Accounts receivable, net	41,393	35,910
Inventories	99,266	102,878
Prepaid expenses and other current assets	15,804	13,252
Total current assets	686,815	601,232
PROPERTY AND EQUIPMENT, net	179,824	166,188
INTANGIBLE ASSETS, net	9,012	12,506
GOODWILL	91,849	91,849
DEFERRED TAX ASSETS	16,433	3,339
OTHER ASSETS	30,554	28,225
Total assets	1,014,487	903,339
CURRENT LIABILITIES:
Accounts payable	43,721	34,712
Accrued payroll and related expenses	15,492	14,806
Taxes payable	1,210	902
Other accrued liabilities	11,898	12,106
Total current liabilities	72,321	62,526
LONG-TERM INCOME TAXES PAYABLE	15,280	15,588
OTHER LIABILITIES	14,854	14,814
Total liabilities	102,455	92,928
COMMITMENTS AND CONTINGENCIES (Notes 11, 12 and 13)
STOCKHOLDERS' EQUITY:
Common stock, $0.001 par value, Authorized - 140,000 shares, Outstanding - 59,913 and 59,910 shares in 2021 and 2020, respectively	28	28
Additional paid-in capital	162,301	190,920
Accumulated other comprehensive loss	(3,737)	(2,163)
Retained earnings	753,440	621,626
Total stockholders' equity	912,032	810,411
Total liabilities and stockholders' equity	$ 1,014,487	$ 903,339

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares shares in Thousands	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Common stock, par value per share	$ 0.001	$ 0.001
Common stock, shares authorized	140,000	140,000
Common stock, shares outstanding	59,913	59,910

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
NET REVENUES	$ 703,277	$ 488,318	$ 420,669
COST OF REVENUES	342,638	244,728	207,267
GROSS PROFIT	360,639	243,590	213,402
OPERATING EXPENSES:
Research and development	84,933	81,711	73,470
Sales and marketing	60,808	54,497	54,297
General and administrative	39,840	36,895	37,582
Litigation settlement	0	0	(168,969)
Total operating expenses	185,581	173,103	(3,620)
INCOME FROM OPERATIONS	175,058	70,487	217,022
OTHER INCOME	1,077	4,764	5,392
INCOME BEFORE INCOME TAXES	176,135	75,251	222,414
PROVISION FOR INCOME TAXES	11,722	4,075	28,946
NET INCOME	$ 164,413	$ 71,176	$ 193,468
EARNINGS PER SHARE:
Basic (in dollars per share)	$ 2.73	$ 1.19	$ 3.31
Diluted (in dollars per share)	$ 2.67	$ 1.17	$ 3.24
SHARES USED IN PER SHARE CALCULATION:
Basic (in shares)	60,327	59,657	58,534
Diluted (in shares)	61,467	60,845	59,632

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 164,413	$ 71,176	$ 193,468
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2021, 2020 and 2019	(486)	(183)	(518)
Unrealized gain (loss) on marketable securities, net of $0 tax in 2021, 2020 and 2019	(2,055)	307	849
Unrealized actuarial gain (loss) on pension benefits, net of tax of ($334), ($308) and $497 in 2021, 2020 and 2019, respectively	967	843	(1,772)
Total other comprehensive income (loss)	(1,574)	967	(1,441)
TOTAL COMPREHENSIVE INCOME	$ 162,839	$ 72,143	$ 192,027

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustments, tax	$ 0	$ 0	$ 0
Unrealized gain (loss) on marketable securities, tax	0	0	0
Amortization of defined benefit pension items, tax	$ (334)	$ (308)	$ 497

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total
Beginning Balance (in shares) at Dec. 31, 2018	57,778
Beginning balance at Dec. 31, 2018	$ 28	$ 126,164	$ (1,689)	$ 402,569	$ 527,072
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	1,130
Issuance of common stock under employee stock option and stock award plans		4,359			4,359
Repurchase of common stock (in shares)	(242)
Repurchase of common stock		(7,302)			(7,302)
Issuance of common stock under employee stock purchase plan (in shares)	196
Issuance of common stock under employee stock purchase plan		5,549			5,549
Stock-based compensation expense related to employee stock options and awards		21,686			21,686
Stock-based compensation expense related to employee stock purchases		1,661			1,661
Payment of dividends to stockholders				(20,506)	(20,506)
Unrealized actuarial gain (loss) on pension benefits			(1,772)		(1,772)
Unrealized (loss) gain on marketable securities			849		849
Foreign currency translation adjustment			(518)		(518)
Net income				193,468	193,468
Ending Balance (in shares) at Dec. 31, 2019	58,862
Ending balance at Dec. 31, 2019	$ 28	152,117	(3,130)	575,531	724,546
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	963
Issuance of common stock under employee stock option and stock award plans		4,608			4,608
Repurchase of common stock (in shares)	(63)
Repurchase of common stock		(2,636)			(2,636)
Issuance of common stock under employee stock purchase plan (in shares)	148
Issuance of common stock under employee stock purchase plan		5,919			5,919
Stock-based compensation expense related to employee stock options and awards		28,952			28,952
Stock-based compensation expense related to employee stock purchases		1,960			1,960
Payment of dividends to stockholders				(25,081)	(25,081)
Unrealized actuarial gain (loss) on pension benefits			843		843
Unrealized (loss) gain on marketable securities			307		307
Foreign currency translation adjustment			(183)		(183)
Net income				71,176	71,176
Ending Balance (in shares) at Dec. 31, 2020	59,910
Ending balance at Dec. 31, 2020	$ 28	190,920	(2,163)	621,626	810,411
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	780
Issuance of common stock under employee stock option and stock award plans		1,644			1,644
Repurchase of common stock (in shares)	(878)
Repurchase of common stock	$ (1)	(73,937)			(73,938)
Issuance of common stock under employee stock purchase plan (in shares)	101
Issuance of common stock under employee stock purchase plan	$ 1	6,065			6,066
Stock-based compensation expense related to employee stock options and awards		35,647			35,647
Stock-based compensation expense related to employee stock purchases		1,962			1,962
Payment of dividends to stockholders				(32,599)	(32,599)
Unrealized actuarial gain (loss) on pension benefits			967		967
Unrealized (loss) gain on marketable securities			(2,055)		(2,055)
Foreign currency translation adjustment			(486)		(486)
Net income				164,413	164,413
Ending Balance (in shares) at Dec. 31, 2021	59,913
Ending balance at Dec. 31, 2021	$ 28	$ 162,301	$ (3,737)	$ 753,440	$ 912,032

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 164,413	$ 71,176	$ 193,468
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	31,454	23,743	19,190
Amortization of intangibles	3,494	4,359	5,213
Loss on disposal of property and equipment	3,105	525	249
Stock-based compensation expense	37,609	30,912	23,347
Amortization of premium on marketable securities	1,590	705	(192)
Deferred income taxes	(13,240)	(592)	4,019
Increase (decrease) in accounts receivable allowance for credit losses	18	(336)	57
Change in operating assets and liabilities:
Accounts receivable	(5,501)	(11,300)	(13,259)
Inventories	3,612	(12,498)	(9,523)
Prepaid expenses and other assets	4,326	9,153	(2,132)
Accounts payable	4,067	5,697	(6,556)
Taxes payable and accrued liabilities	(4,079)	4,095	10,618
Net cash provided by operating activities	230,868	125,639	224,499
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(47,272)	(70,598)	(24,114)
Proceeds from sale of property and equipment	35	651	0
Acquisition of technology licenses	0	0	(1,026)
Purchases of marketable securities	(554,018)	(109,703)	(207,240)
Proceeds from sales and maturities of marketable securities	368,457	151,385	70,334
Net cash used in investing activities	(232,798)	(28,265)	(162,046)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	7,710	10,527	9,908
Repurchase of common stock	(73,938)	(2,636)	(7,302)
Payments of dividends to stockholders	(32,599)	(25,081)	(20,506)
Net cash used in financing activities	(98,827)	(17,190)	(17,900)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(100,757)	80,184	44,553
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	258,874	178,690	134,137
CASH AND CASH EQUIVALENTS AT END OF PERIOD	158,117	258,874	178,690
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	10,879	5,937	4,355
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid (received) for income taxes, net	$ 25,644	$ (1,973)	$ 21,327

THE COMPANY

THE COMPANY	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements Abstract
THE COMPANY	1. THE COMPANY: Power Integrations, Inc. (“Power Integrations” or the “Company”), incorporated in California on March 25, 1988, and reincorporated in Delaware in December 1997, designs, develops, manufactures and markets analog and mixed-signal integrated circuits (ICs) and other electronic components and circuitry used in high-voltage power conversion. The Company’s products are used in power converters that convert electricity from a high-voltage source to the type of power required for a specified downstream use. A large percentage of the Company’s products are ICs used in AC-DC power supplies, which convert the high-voltage AC from a wall outlet to the low-voltage DC required by most electronic devices. Power supplies incorporating the Company’s products are used with all manner of electronic products including mobile phones, computing and networking equipment, appliances, electronic utility meters, battery-powered tools, industrial controls, and “home-automation,” or “internet of things” applications such as networked thermostats, power strips and other building-automation and security devices. The Company also supplies high-voltage LED drivers, which are AC-DC ICs specifically designed for lighting applications that utilize light-emitting diodes. In 2018, the Company introduced a new category of power-conversion ICs: a family of motor-driver ICs addressing brushless DC (BLDC) motors used in refrigerators, HVAC systems, ceiling fans and other consumer-appliance and light commercial applications. The Company also offers high-voltage gate drivers—either standalone ICs or circuit boards containing ICs, electrical isolation components and other circuitry—used to operate high-voltage switches such as insulated-gate bipolar transistors (IGBTs) and silicon-carbide (SiC) MOSFETs. These combinations of switches and drivers are used for power conversion in high-power applications (i.e., power levels ranging from a few kilowatts up to gigawatts) such as industrial motors, solar- and wind-power systems, electric vehicles and high-voltage DC transmission systems.

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS	2. SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS: Significant Accounting Policies and Estimates Segment Reporting The Company is organized and operates as one reportable segment, the design, development, manufacture and marketing of integrated circuits and related components for use primarily in the high-voltage power conversion markets. The Company’s chief operating decision maker, the Chief Executive Officer, reviews financial information presented on a consolidated basis for purposes of making operating decisions and assessing financial performance. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries after elimination of all intercompany transactions and balances. Estimates The preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to revenue recognition, allowances for receivables, inventories, litigation and income taxes. These estimates are based on historical facts and various other factors, which the Company believes to be reasonable at the time the estimates are made. However, as the effects of future events cannot be determined with precision, actual results could differ significantly from management’s estimates. Revenue Recognition The Company applies the provisions of Accounting Standards Codification (ASC) 606-10, Revenue from Contracts with Customers the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when a performance obligation is satisfied. Product revenues consist of sales to original equipment manufacturers, or OEMs, merchant power supply manufacturers and distributors. The Company considers customer purchase orders, which in some cases are governed by master sales agreements, to be the contracts with a customer. In situations where sales are to a distributor, the Company has concluded that its contracts are with the distributor as the Company holds a contract bearing enforceable rights and obligations only with the distributor. As part of its consideration of the contract, the Company evaluates certain factors including the customer’s ability to pay (or credit risk). For each contract, the Company considers the promise to transfer products, each of which is distinct, to be the identified performance obligations. In determining the transaction price the Company evaluates whether the price is subject to refund or adjustment to determine the net consideration to which the Company expects to be entitled. As the Company’s standard payment terms are less than one year, the Company has elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company allocates the transaction price to each distinct product based on their relative standalone selling price. The product price as specified on the purchase order is considered the standalone selling price as it is an observable input which depicts the price as if sold to a similar customer in similar circumstances. Revenue is recognized when control of the product is transferred to the customer (i.e., when the Company’s performance obligation is satisfied), which typically occurs at shipment. Further, in determining whether control has transferred, the Company considers if there is a present right to payment and legal title, along with risks and rewards of ownership having transferred to the customer. Frequently, the Company receives orders for products to be delivered over multiple dates that may extend across several reporting periods. The Company invoices for each delivery upon shipment and recognizes revenues for each distinct product delivered, assuming transfer of control has occurred. As scheduled delivery dates are within one year, under the optional exemption provided by ASC 606-10-50-14 revenues allocated to future shipments of partially completed contracts are not disclosed. The Company has also elected the practical expedient under ASC 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year. Sales to international customers that are shipped from the Company’s facility outside of the United States are pursuant to EX Works, or EXW, shipping terms, meaning that control of the product transfers to the customer upon shipment from the Company’s foreign warehouse. Sales to international customers that are shipped from the Company’s facility in California are pursuant to Delivered at Frontier, or DAF, shipping terms. As such, control of the product passes to the customer when the shipment reaches the destination country and revenue is recognized upon the arrival of the product in that country. Shipments to customers in the Americas are pursuant to Free on Board, or FOB, point of origin shipping terms meaning that control is passed to the customer upon shipment. Sales to most distributors are made under terms allowing certain price adjustments and limited rights of return (known as “stock rotation”) of the Company’s products held in their inventory or upon sale to their end customers. Revenue from sales to distributors is recognized upon the transfer of control to the distributor. Frequently, distributors need to sell at a price lower than the standard distribution price in order to win business. At the time the distributor invoices its customer or soon thereafter, the distributor submits a “ship and debit” price adjustment claim to the Company to adjust the distributor’s cost from the standard price to the pre-approved lower price. After the Company verifies that the claim was pre-approved, a credit memo is issued to the distributor for the ship and debit claim. In determining the transaction price, the Company considers ship and debit price adjustments to be variable consideration. Such price adjustments are estimated using the expected value method based on an analysis of actual ship and debit claims, at the distributor and product level, over a period of time considered adequate to account for current pricing and business trends. Historically, actual price adjustments for ship and debit claims relative to those estimated and included when determining the transaction price have not materially differed. Stock rotation rights grant the distributor the ability to return certain specified amounts of inventory. Stock rotation adjustments are an additional form of variable consideration and are also estimated using the expected value method based on historical return rates. Historically, distributor stock rotation adjustments have not been material. Sales to certain distributors are made under terms that do not include rights of return or price concessions after the product is shipped to the distributor. Accordingly, upon application of steps one through five above, product revenue is recognized upon shipment and transfer of control. The Company generally provides an assurance warranty that its products will substantially conform to the published specifications for twelve months from the date of shipment. The Company’s liability is limited to either a credit equal to the purchase price or replacement of the defective part. Returns under warranty have historically been immaterial. As such, the Company does not record a specific warranty reserve or consider activities related to such warranty, if any, to be a separate performance obligation. Inventories Inventories (which consist of costs associated with the purchases of wafers from domestic and offshore foundries and of packaged components from offshore assembly manufacturers, as well as internal labor and overhead associated with the testing of both wafers and packaged components) are stated at the lower of cost (first-in, first-out) or market. Provisions, when required, are made to reduce inventories to their estimated net realizable values. Income Taxes Income-tax expense is an estimate of current income taxes payable or refundable in the current fiscal year based on reported income before income taxes. Deferred income taxes reflect the effect of temporary differences and carry-forwards that are recognized for financial reporting and income tax purposes. The Company accounts for income taxes under the provisions of ASC 740, Income Taxe Goodwill and Intangible Assets Goodwill and the Company’s domain name are evaluated in accordance with ASC 350-10, Goodwill and Other Intangible Assets, In accordance with ASC 360-10, Accounting for the Impairment or Disposal of Long-Lived Assets Cash and Cash Equivalents The Company considers cash invested in highly liquid financial instruments with maturities of three months or less at the date of purchase to be cash equivalents. Marketable Securities The Company generally holds securities until maturity; however, they may be sold under certain circumstances including, but not limited to, when necessary for the funding of acquisitions and other strategic investments. As a result, the Company classifies its investment portfolio as available-for-sale. The Company classifies all investments with a maturity date greater than three months at the date of purchase as short-term marketable securities in its consolidated balance sheet. As of December 31, 2021 and 2020, the Company’s marketable securities consisted primarily of commercial paper, corporate bonds, government securities and/or other high-quality commercial securities. Employee Benefits Plan The Company sponsors a 401(k) tax-deferred savings plan for all employees in the United States who meet certain eligibility requirements. Participants may contribute up to the amount allowable as a deduction for federal income tax purposes. The Company is not required to contribute; however, the Company contributes a certain percentage of employee annual salaries on a discretionary basis, not to exceed an established threshold. The Company provided for a contribution of approximately $1.9 million, $1.8 million and $1.4 million in 2021, 2020 and 2019, respectively. Retirement Benefit Obligations (Pension) The Company recognizes the over-funded or under-funded status of a defined benefit pension or post-retirement plan as an asset or liability in the accompanying consolidated balance sheets. Actuarial gains and losses are recorded in accumulated other comprehensive loss, a component of stockholders’ equity, and are amortized as a component of net periodic cost over the remaining estimated service period of participants. Foreign Currency Risk and Foreign Currency Translation As of December 31, 2021, the Company’s primary transactional currency was U.S. dollars; in addition, the Company holds cash in Swiss francs and euros to fund the operations of the Company’s Swiss subsidiary. The foreign exchange rate fluctuation between the U.S. dollar versus the Swiss franc and euro is recorded in other income in the consolidated statements of income. Gains and losses arising from the remeasurement of non-functional currency balances are recorded in other income in the accompanying consolidated statements of income. The Company realized a foreign exchange transaction loss of $0.6 million, $0.5 million and $0.3 million in 2021, 2020 and 2019 respectively. The functional currencies of the Company’s other subsidiaries are the local currencies. Accordingly, all assets and liabilities are translated into U.S. dollars at the current exchange rates as of the applicable balance sheet date. Revenues and expenses are translated at the average exchange rate prevailing during the period. Cumulative gains and losses from the translation of the foreign subsidiaries’ financial statements have been included accumulated other comprehensive loss in stockholders’ equity. Warranty The Company generally warrants that its products will substantially conform to the published specifications for 12 months Advertising Advertising costs are expensed as incurred and amounted to $1.3 million, $1.2 million and $1.4 million in 2021, 2020 and 2019, respectively. Research and Development Research and development costs are expensed as incurred. Indemnifications The Company sells products to its distributors under contracts, collectively referred to as Distributor Sales Agreements (DSA). Each DSA contains the relevant terms of the contractual arrangement with the distributor, and generally includes certain provisions for indemnifying the distributor against losses, expenses, and liabilities from damages that may be awarded against the distributor in the event the Company’s products are found to infringe upon a patent, copyright, trademark, or other proprietary right of a third party (Customer Indemnification). The DSA generally limits the scope of and remedies for the Customer Indemnification obligations in a variety of industry-standard respects, including, but not limited to, limitations based on time and geography, and a right to replace an infringing product. The Company also, from time to time, has granted a specific indemnification right to individual customers. The Company believes its internal development processes and other policies and practices limit its exposure related to such indemnifications. In addition, the Company requires its employees to sign a proprietary information and inventions agreement, which assigns the rights to its employees’ development work to the Company. To date, the Company has not had to reimburse any of its distributors or customers for any losses related to these indemnifications and no material claims were outstanding as of December 31, 2021. For several reasons, including the lack of prior indemnification claims and the lack of a monetary liability limit for certain infringement cases, the Company cannot determine the maximum amount of potential future payments, if any, related to such indemnifications. Recent Accounting Pronouncements The Company has considered all recent accounting pronouncements issued, but not yet effective, and does not expect any to have a material effect on the Company’s condensed consolidated financial statements. ​

COMPONENTS OF THE COMPANY'S CON

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures Abstract
COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS	3. COMPONENTS OF THE COMPANY’S CONSOLIDATED BALANCE SHEETS: Accounts Receivable ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Accounts receivable trade ​ $ 87,503 ​ $ 66,703 Allowance for ship and debit ​ (41,599) ​ (26,435) Allowance for stock rotation and rebate ​ (4,066) ​ (3,931) Allowance for credit losses ​ ​ (445) ​ ​ (427) Total ​ $ 41,393 ​ $ 35,910 ​ The Company maintains an allowance for estimated credit losses resulting from the inability of customers to make required payments. This allowance is established using estimates formulated by the Company’s management based upon factors such as the composition of the accounts receivable aging, historical losses, changes in payments patterns, customer creditworthiness, and current economic trends. Receivables determined to be uncollectible are written off and deducted from the allowance. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, (In thousands) ​ 2021 2020 Beginning balance ​ $ (427) ​ $ (763) Provision for credit loss expense ​ (1,023) ​ (621) Receivables written off ​ 74 ​ 198 Recoveries collected ​ 931 ​ 759 Ending balance ​ $ (445) ​ $ (427) ​ Inventories ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Raw materials ​ $ 24,131 ​ $ 32,131 Work-in-process ​ 31,788 ​ 39,469 Finished goods ​ 43,347 ​ 31,278 Total ​ $ 99,266 ​ $ 102,878 ​ Property and Equipment ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Land ​ $ 22,187 ​ $ 22,189 Construction-in-progress ​ 22,661 ​ 34,886 Building and improvements ​ 81,027 ​ 64,808 Machinery and equipment ​ 235,066 ​ 202,698 Computer software and hardware and office furniture and fixtures ​ 57,926 ​ 55,591 Total ​ 418,867 ​ 380,172 Less: Accumulated depreciation ​ (239,043) ​ (213,984) Property and equipment, net ​ $ 179,824 ​ $ 166,188 ​ Depreciation expense for property and equipment for fiscal years ended December 31, 2021, 2020 and 2019, was approximately $31.5 million, $23.7 million and $19.2 million, respectively, and was determined using the straight-line method over the following useful lives: ​ ​ ​ ​ ​ ​ Building and improvements ​ ​ 4 - 40 years Machinery and equipment ​ 2 - 8 years Computer software and hardware and office furniture and fixtures ​ 4 - 7 years ​ Total property and equipment (excluding accumulated depreciation) located in the United States at December 31, 2021, 2020 and 2019, was approximately $174.6 million, $167.0 million and $160.7 million, respectively. In 2021, 2020 and 2019, approximately 14%, 14% and 14%, respectively, of total property and equipment (excluding accumulated depreciation) was held in Thailand by one of the Company’s subcontractors. Also in 2021 and 2020, approximately 15% and 14% of total property and equipment (excluding accumulated depreciation) was held by one of the Company’s subcontractors in Malaysia. No other country held 10% or more of total property and equipment in the periods presented. Accumulated Other Comprehensive Loss Changes in accumulated other comprehensive loss for the three years ended December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ Available-for-Sale ​ Defined Benefit ​ Currency ​ ​ ​ (In thousands) ​ Securities ​ Pension Items ​ Items ​ Total Balance at January 1, 2019 ​ $ (266) ​ $ (712) ​ $ (711) ​ $ (1,689) Other comprehensive income (loss) before reclassifications ​ 849 ​ (1,839) ​ (518) ​ (1,508) Amounts reclassified from accumulated other comprehensive loss ​ — ​ 67 (1) — ​ 67 Other comprehensive loss ​ 849 ​ (1,772) ​ (518) ​ (1,441) Balance at December 31, 2019 ​ 583 ​ (2,484) ​ (1,229) ​ (3,130) Other comprehensive income (loss) before reclassifications ​ 307 ​ 636 ​ (183) ​ 760 Amounts reclassified from accumulated other comprehensive loss ​ — ​ 207 (1) — ​ 207 Other comprehensive income ​ 307 ​ 843 ​ (183) ​ 967 Balance at December 31, 2020 ​ 890 ​ (1,641) ​ (1,412) ​ (2,163) Other comprehensive income (loss) before reclassifications ​ (2,055) ​ 800 ​ (486) ​ (1,741) Amounts reclassified from accumulated other comprehensive loss ​ — ​ 167 (1) — ​ 167 Other comprehensive loss ​ (2,055) ​ 967 ​ (486) ​ (1,574) Balance at December 31, 2021 ​ $ (1,165) ​ $ (674) ​ $ (1,898) ​ $ (3,737) (1) This component of accumulated other comprehensive loss is included in the computation of net periodic pension cost for the years ended December 31, 2021, 2020 and 2019.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures Abstract
FAIR VALUE MEASUREMENTS	4. FAIR VALUE MEASUREMENTS: ASC 820-10, Fair Value Measurements The Company’s cash equivalents and investment instruments are classified within Level 1 or Level 2 of the fair-value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The type of instrument valued based on quoted market prices in active markets primarily includes money market securities. This type of instrument is generally classified within Level 1 of the fair-value hierarchy. The types of instruments valued based on other observable inputs (Level 2 of the fair-value hierarchy) include investment-grade corporate bonds and commercial paper. Such types of investments are valued by using a multi-dimensional relational model, the inputs are primarily benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. The Company does not hold any instruments that would be classified within Level 3 of the fair-value hierarchy. The fair value hierarchy of the Company’s cash equivalents and marketable securities at December 31, 2021, and 2020, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2021 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 172,237 ​ $ — ​ $ 172,237 Corporate securities ​ ​ 282,540 ​ ​ — ​ ​ 282,540 Money market funds ​ 29,793 ​ 29,793 ​ — Total ​ $ 484,570 ​ $ 29,793 ​ $ 454,777 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2020 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 253,855 ​ $ — ​ $ 253,855 Corporate securities ​ ​ 146,658 ​ ​ — ​ ​ 146,658 Money market funds ​ 1,634 ​ 1,634 ​ — Total ​ $ 402,147 ​ $ 1,634 ​ $ 400,513 ​ The Company did not transfer any investments between level 1 and level 2 of the fair value hierarchy in the years ended December 31, 2021, and 2020.

MARKETABLE SECURITIES

MARKETABLE SECURITIES	12 Months Ended
	Dec. 31, 2021
Marketable Securities Abstract
MARKETABLE SECURITIES	5. MARKETABLE SECURITIES: Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2021, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 89,965 ​ $ — ​ $ — ​ $ 89,965 Corporate securities ​ ​ 7,285 ​ ​ — ​ ​ (3) ​ ​ 7,282 Total ​ 97,250 ​ — ​ (3) ​ 97,247 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 25,054 ​ — ​ (42) ​ 25,012 Total ​ 25,054 ​ — ​ (42) ​ 25,012 Investments due in 12 months or greater: ​ ​ ​ ​ Corporate securities ​ 251,096 ​ 21 ​ (1,141) ​ 249,976 Total ​ ​ 251,096 ​ 21 ​ ​ (1,141) ​ 249,976 Total marketable securities ​ $ 373,400 ​ $ 21 ​ $ (1,186) ​ $ 372,235 ​ Accrued interest receivable was $1.5 million at December 31, 2021 and was recorded within prepaid expenses and other current assets on the condensed consolidated balance sheet. Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 43,660 ​ $ — ​ $ — ​ $ 43,660 Corporate securities ​ ​ 19,846 ​ ​ 44 ​ ​ — ​ ​ 19,890 Total ​ 63,506 ​ 44 ​ — ​ 63,550 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 125,922 ​ 846 ​ — ​ 126,768 Total ​ 125,922 ​ 846 ​ — ​ 126,768 Total marketable securities ​ $ 189,428 ​ $ 890 ​ $ — ​ $ 190,318 ​ The Company did not have any investments due in twelve months or greater as of December 31, 2020. Accrued interest receivable was $0.8 million at December 31, 2020 and was recorded within prepaid expenses and other current assets on the condensed consolidated balance sheet. ​ As of December 31, 2021, the Company had no marketable securities classified as available-for-sale (excluding cash equivalents) in a continuous unrealized loss position for which an allowance for credit losses was recorded. The following table summarizes marketable securities classified as available-for-sale (excluding cash equivalents) in a continuous unrealized loss position for which an allowance for credit losses was not recorded at December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less Than 12 Months ​ 12 Months or Longer ​ Total ​ Estimated Gross Estimated Gross Estimated Gross ​ ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized (In thousands) ​ Value ​ Losses ​ Value ​ Losses ​ Value ​ Losses Corporate securities ​ $ 274,380 ​ $ (1,186) ​ $ — ​ $ — ​ $ 274,380 ​ $ (1,186) Total marketable securities ​ $ 274,380 ​ $ (1,186) ​ $ — ​ $ — ​ $ 274,380 ​ $ (1,186) ​ As of December 31, 2020, the Company had no marketable securities classified as available-for-sale (excluding cash equivalents) in a continuous unrealized loss position for which an allowance for credit losses was recorded. ​ The weighted average interest rate of investments at December 31, 2021 and 2020, was approximately 0.45% and 0.89%, respectively. In the year ended December 31, 2021 and 2020, no unrealized losses on marketable securities were recognized in income.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	6. GOODWILL AND INTANGIBLE ASSETS: The carrying amount of goodwill as of December 31, 2021 and 2020 was $91.8 million; there were no changes to goodwill in either of the respective fiscal years. Intangible assets consist primarily of developed technology, acquired licenses, customer relationships, trade name, domain name, in-process R&D and patent rights, and are reported net of accumulated amortization. The Company amortizes the cost of all intangible assets over the shorter of the estimated useful life or the term of the developed technology, customer relationships, technology licenses and in-place leases, which range from two www.power.com ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ December 31, 2020 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ (In thousands) ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Domain name ​ $ 1,261 ​ $ — ​ $ 1,261 ​ $ 1,261 ​ $ — ​ $ 1,261 Developed technology ​ 37,960 ​ (31,603) ​ 6,357 ​ 37,960 ​ (29,126) ​ 8,834 Customer relationships ​ 16,700 ​ (16,458) ​ 242 ​ 16,700 ​ (15,687) ​ 1,013 Technology licenses ​ 1,926 ​ (774) ​ 1,152 ​ 1,926 ​ (528) ​ 1,398 Total intangible assets ​ $ 57,847 ​ $ (48,835) ​ $ 9,012 ​ $ 57,847 ​ $ (45,341) ​ $ 12,506 ​ The estimated future amortization expense related to definite-lived intangible assets at December 31, 2021, is as follows: ​ ​ ​ ​ ​ Estimated ​ ​ Amortization Fiscal Year ​ (In thousands) 2022 ​ $ 2,415 2023 ​ 2,173 2024 ​ 1,279 2025 ​ 832 2026 ​ 687 Thereafter ​ 365 Total ​ $ 7,751 ​

STOCK PLANS AND SHARE BASED COM

STOCK PLANS AND SHARE BASED COMPENSATION	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
STOCK PLANS AND SHARE BASED COMPENSATION	7. STOCK PLANS AND SHARE BASED COMPENSATION: The share and per share information for all periods presented in this Form 10-K has been adjusted for the effect of the August 2020 stock split. Refer to Note 10, Earnings Per Share , in this Form 10-K for details. Stock Plans As of December 31, 2021, the Company had three stock-based compensation plans (the “Plans”) which are described below. 2007 Equity Incentive Plan The 2007 Equity Incentive Plan (2007 Plan) was adopted by the board of directors on September 10, 2007, and approved by the stockholders on November 7, 2007, as an amendment and restatement of the 1997 Stock Option Plan (1997 Plan). The 2007 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit (RSU) awards, stock appreciation rights, performance-based (PSU) awards, long-term performance based (PRSU) awards and other stock awards to employees, directors and consultants. Pursuant to the 2007 Plan, the exercise price for incentive stock options and non-statutory stock options is generally at least 100% of the fair market value of the underlying shares on the date of grant. Options generally vest over 48 months measured from the date of grant. Options generally expire no later than ten years after the date of grant, subject to earlier termination upon an optionee’s cessation of employment or service. The 2007 Plan expired in September 2017 with no further grants to be made under this plan; however previous grants under this plan shall remain outstanding until they are exercised, vest, forfeited or expire. 2016 Incentive Award Plan The 2016 Incentive Award Plan (2016 Plan) was adopted by the board of directors on March 17, 2016 and approved by the stockholders on May 13, 2016. The 2016 Plan provides for the grant of RSU awards, PSU awards and PRSU awards. No other forms of equity-based awards, including stock options and stock appreciation rights, may be granted under the 2016 Plan. As of December 31, 2021, 2.6 million awards have been issued, net of forfeitures or cancellations, and approximately 4.4 million shares of common stock remain available for future grant under the 2016 Plan. 1997 Employee Stock Purchase Plan Under the 1997 Employee Stock Purchase Plan (Purchase Plan), eligible employees may apply accumulated payroll deductions, which may not exceed 15% of an employee’s compensation, to the purchase of shares of the Company’s common stock at periodic intervals. The purchase price of stock under the Purchase Plan is equal to 85% of the lower of (i) the fair market value of the Company’s common stock on the first day of each offering period, or (ii) the fair market value of the Company’s common stock on the purchase date (as defined in the Purchase Plan). Each offering period consists of one purchase period of approximately six months Shares Reserved As of December 31, 2021, the Company had approximately 5.5 million shares of common stock reserved for future grant under all stock plans. Stock-Based Compensation The Company applies the provisions of ASC 718-10, Stock Compensation The following table summarizes the stock-based compensation expense recognized in accordance with ASC 718-10 for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 Cost of revenues ​ $ 2,359 ​ $ 1,963 ​ $ 1,237 Research and development ​ 12,127 ​ 10,378 ​ 8,423 Sales and marketing ​ 7,630 ​ 6,290 ​ 5,015 General and administrative ​ 15,493 ​ 12,281 ​ 8,672 Total stock-based compensation expense ​ $ 37,609 ​ $ 30,912 ​ $ 23,347 ​ The following table summarizes total compensation expense related to unvested awards not yet recognized, net of expected forfeitures, and the weighted average period over which it is expected to be recognized as of December 31, 2021: ​ ​ ​ ​ ​ ​ ​ Unrecognized Compensation Weighted Average ​ ​ Expense for Unvested ​ Remaining Recognition ​ ​ Awards ​ Period ​ ​ (In thousands) ​ (In years) Long-term performance-based awards ​ $ 7,474 1.19 Restricted stock units ​ 35,707 2.26 Purchase plan ​ 174 0.08 Total unrecognized compensation expense ​ $ 43,355 ​ Stock-based compensation expense in the year ended December 31, 2021, was approximately $37.6 million, comprising approximately $19.9 million related to restricted stock units, $15.7 million related to performance-based awards and $2.0 million related to the Company’s Purchase Plan. Stock-based compensation expense in the year ended December 31, 2020, was approximately $30.9 million, comprising approximately $18.7 million related to restricted stock units, $10.2 million related to performance-based awards and $2.0 million related to the Company’s Purchase Plan. Stock-based compensation expense in the year ended December 31, 2019, was approximately $23.3 million, comprising approximately $17.5 million related to restricted stock units, $4.1 million related to performance-based awards and $1.7 million related to the Company’s Purchase Plan. The Company did not grant stock options in the years ended December 31, 2021, 2020 and 2019, and therefore no fair-value assumptions are reported. The fair value of employees’ stock purchase rights under the Purchase Plan was estimated using the Black-Scholes model with the following weighted-average assumptions used during the three years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ 2019 Risk-free interest rates ​ 0.07 % ​ ​ 0.90 % ​ ​ 2.28 % Expected volatility rates ​ 41 % ​ ​ 47 % ​ ​ 37 % Expected dividend yield ​ 0.57 % ​ ​ 0.78 % ​ ​ 0.91 % Expected term of purchase rights (in years) ​ 0.50 ​ ​ 0.50 ​ ​ 0.50 Weighted-average estimated fair value of purchase rights ​ $ 23.92 ​ ​ $ 15.73 ​ ​ $ 19.39 ​ ​ A summary of stock options outstanding as of December 31, 2021, and activity during three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Exercise ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Price (In years) (In thousands) Outstanding at January 1, 2019 670 ​ $ 16.21 ​ Granted — ​ — ​ Exercised (335) ​ $ 12.98 ​ Forfeited or expired — ​ — ​ Outstanding at December 31, 2019 335 ​ $ 19.44 ​ Granted — ​ — ​ Exercised (243) ​ $ 18.99 ​ Forfeited or expired — ​ — ​ Outstanding at December 31, 2020 92 ​ $ 20.63 ​ Granted — ​ ​ — ​ Exercised (80) ​ $ 20.50 ​ Forfeited or expired — ​ ​ — ​ Outstanding at December 31, 2021 12 ​ $ 21.44 0.35 ​ $ 857 Vested and Exercisable at December 31, 2021 12 ​ ​ ​ 0.35 ​ $ 857 ​ The total intrinsic value of options exercised during the year ended December 31, 2021, 2020 and 2019, was $4.9 million, $9.1 million and $8.3 million, respectively. The following table summarizes the stock options outstanding at December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ Options Exercisable ​ ​ Weighted Average Weighted ​ Weighted ​ ​ ​ ​ Remaining ​ Average ​ ​ ​ Average (Shares in thousands) ​ Options ​ Contractual Term ​ Exercise ​ Options ​ Exercise Range of Exercise Prices ​ Outstanding ​ (In years) ​ Price ​ Exercisable ​ Price $21.44 - $21.44 12 0.35 ​ $ 21.44 12 ​ $ 21.44 ​ PSU Awards Under the performance-based awards program, the Company grants awards in the performance year in an amount equal to twice the target number of shares to be issued if the maximum performance metrics are met. The number of shares that are released at the end of the performance year can range from zero to 200% of the target number depending on the Company’s performance. The performance metrics of this program are annual targets consisting of a combination of net revenue, non-GAAP operating earnings and strategic goals. As the net revenue, non-GAAP operating income and strategic goals are considered performance conditions, expense associated with these awards, net of estimated forfeitures, is recognized over the service period based on an assessment of the achievement of the performance targets. The fair value of these PSUs is determined using the fair value of the Company’s common stock on the date of the grant, reduced by the discounted present value of dividends expected to be declared before the awards vest. If the performance conditions are not achieved, no compensation cost is recognized and any previously recognized compensation is reversed. A summary of PSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 52 ​ $ 31.44 ​ Granted 185 ​ $ 35.06 ​ Vested (52) ​ $ 31.44 ​ Forfeited or canceled (64) ​ $ 35.06 ​ Outstanding at December 31, 2019 121 ​ $ 35.06 ​ Granted 150 ​ $ 46.31 ​ Vested (121) ​ $ 35.06 ​ Forfeited or canceled — ​ ​ — ​ Outstanding at December 31, 2020 150 ​ $ 46.27 ​ Granted 105 ​ $ 84.48 ​ Vested (150) ​ $ 46.27 ​ Forfeited or canceled (1) ​ $ 85.01 ​ Outstanding at December 31, 2021 104 ​ $ 84.47 — ​ $ 9,701 Outstanding and expected to vest at December 31, 2021 104 ​ ​ ​ — ​ $ 9,701 ​ In January 2021, it was determined that approximately 150,000 shares subject to the PSUs granted in 2020 vested in aggregate; the shares were released to the Company’s employees and executives in the first quarter of 2021. The grant-date fair value of PSU awards released, which were fully vested, in the years ended December 31, 2021, 2020 and 2019 was approximately $6.9 million, $4.2 million and $1.6 million, respectively. PRSU Awards (Long-term Performance Based) The Company’s PRSU program provides for the issuance of PRSUs which will vest based on the Company’s performance measured against the PRSU Plan’s established revenue targets. The PRSUs were granted in an amount equal to twice the target number of shares to be issued if the maximum performance metrics are met. The actual number of shares the recipient receives is determined at the end of a three-year performance period based on results achieved versus the Company’s performance goals, and may range from zero to 200% of the target number. Recipients of a PRSU award generally must remain employed by the Company on a continuous basis through the end of the applicable three-year performance period in order to receive shares subject to that award. The performance goals for PRSUs granted in fiscal 2021, 2020 and 2019 were based on the Company’s annual revenue growth over the respective three-year performance period. Expense associated with these awards, net of estimated forfeitures, is recorded throughout the year based on an assessment of the expected achievement of the performance targets. If the performance conditions are not achieved, no compensation cost is recognized and any previously recognized compensation is reversed. A summary of PRSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 426 ​ $ 27.74 ​ Granted 144 ​ $ 34.09 ​ Vested (140) ​ $ 21.63 ​ Forfeited or canceled (143) ​ $ 31.50 ​ Outstanding at December 31, 2019 287 ​ $ 32.03 ​ ​ Granted 152 ​ $ 49.67 ​ Vested — ​ ​ — ​ Forfeited or canceled (138) ​ $ 29.95 ​ Outstanding at December 31, 2020 301 ​ $ 41.90 ​ Granted 103 ​ $ 82.92 ​ Vested (6) ​ $ 29.94 ​ Forfeited or canceled (15) ​ $ 40.05 ​ Outstanding at December 31, 2021 383 ​ $ 53.14 0.92 ​ $ 35,537 Outstanding and expected to vest at December 31, 2021 383 ​ ​ ​ 0.92 ​ $ 35,537 ​ In January 2021 it was determined that approximately 6,000 shares subject to the PRSUs granted in 2018 vested in aggregate; the shares were released to the Company’s executives in the first quarter of 2021. , RSU Awards RSUs granted to employees typically vest ratably over a four-year period, and are converted into shares of the Company’s common stock upon vesting on a one-for-one basis subject to the employee’s continued service to the Company over that period. The fair value of RSUs is determined using the fair value of the Company’s common stock on the date of the grant, reduced by the discounted present value of dividends expected to be declared before the awards vest. Compensation expense is recognized on a straight-line basis over the requisite service period of each grant adjusted for estimated forfeitures. A summary of RSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 1,790 ​ $ 29.10 ​ Granted 582 ​ $ 34.90 ​ Vested (603) ​ $ 28.10 ​ Forfeited (50) ​ $ 31.72 ​ Outstanding at December 31, 2019 1,719 ​ $ 31.33 ​ Granted 439 ​ $ 44.82 ​ Vested (599) ​ $ 30.25 ​ Forfeited (41) ​ $ 36.77 ​ Outstanding at December 31, 2020 1,518 ​ $ 35.51 ​ Granted 271 ​ $ 83.79 ​ Vested (546) ​ $ 35.03 ​ Forfeited (99) ​ $ 39.85 ​ Outstanding at December 31, 2021 1,144 ​ $ 46.81 1.25 ​ $ 106,306 Outstanding and expected to vest at December 31, 2021 1,081 ​ ​ ​ 1.20 ​ $ 100,433 ​ The grant-date fair value of RSUs vested in the years ended December 31, 2021, 2020 and 2019, was approximately $19.1 million, $18.1 million and $16.9 million, respectively.

SIGNIFICANT CUSTOMERS AND GEOGR

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES	12 Months Ended
	Dec. 31, 2021
Risks and Uncertainties Abstract
SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES	8. SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES: Customer Concentration The Company’s top ten customers accounted for approximately 78%, 62% and 54% of revenues in 2021, 2020 and 2019, respectively. A significant portion of these revenues are attributable to sales of the Company’s products to distributors of electronic components. These distributors sell the Company’s products to a broad, diverse range of end users, including OEMs and merchant power supply manufacturers. Sales to distributors in 2021, 2020 and 2019 were $525.7 million, $367.7 million and $304.6 million, respectively. Direct sales to OEMs and power-supply manufacturers accounted for the remainder. The following customers represented 10% or more of the Company’s net revenues for the respective years ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Customer 2021 ​ 2020 ​ 2019 Avnet ​ 30 % ​ 19 % ​ 11 % Honestar Technologies Co., Ltd. 16 % ​ 11 % ​ * ​ *Total customer revenue was less than 10% of net revenues. No other customers accounted for 10% or more of the Company’s net revenues in the periods presented. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consisted principally of cash investments and trade receivables. The Company does not have any off-balance-sheet credit exposure related to its customers. As of December 31, 2021 and 2020, 86% and 90% of accounts receivable were concentrated with the Company’s top ten customers, respectively. The following customers represented 10% or more of accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Customer 2021 ​ 2020 Avnet ​ 45 % ​ 50 % Powertech Distribution Ltd. * % ​ 10 % No other customers accounted for 10% or more of the Company’s accounts receivable in the periods presented. Geographic Net Revenues The Company markets its products globally through its sales personnel and a worldwide network of independent sales representatives and distributors. Geographic net revenues based on “bill to” customer locations were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 United States of America ​ $ 17,238 ​ $ 11,065 ​ $ 10,662 Hong Kong/China ​ 446,980 ​ 306,938 ​ 237,341 Taiwan ​ 25,991 ​ 21,650 ​ 36,297 Korea ​ 59,501 ​ 40,059 ​ 30,395 Western Europe (excluding Germany) ​ 35,835 ​ 33,564 ​ 36,025 Japan ​ 25,101 ​ 17,453 ​ 15,496 Germany ​ 32,664 ​ 23,242 ​ 20,197 Other ​ 59,967 ​ 34,347 ​ 34,256 Total net revenues ​ $ 703,277 ​ $ 488,318 ​ $ 420,669 ​

COMMON STOCK REPURCHASES AND CA

COMMON STOCK REPURCHASES AND CASH DIVIDENDS	12 Months Ended
	Dec. 31, 2021
Equity Abstract
COMMON STOCK REPURCHASES AND CASH DIVIDENDS	9. COMMON STOCK REPURCHASES AND CASH DIVIDENDS: Common Stock Repurchases Over the years the Company’s board of directors has authorized the use of funds to repurchase shares of the Company’s common stock. In October 2018, the Company’s board of director’s authorized the use of $80.0 million for the repurchase of the Company’s common stock, and in each of April 2021 and October 2021 In January 2022, the Company’s board of directors authorized the use of an additional $100.0 million for the repurchase of the Company’s common stock, with repurchases to be executed according to pre-defined price/volume guidelines. Authorization of future stock repurchase programs is at the discretion of the board of directors and will depend on the Company’s financial condition, results of operations, capital requirements and business conditions as well as other factors. Common Stock Dividend The following table presents the quarterly dividends declared per share of the Company’s common stock for the periods indicated: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 2019 First Quarter ​ $ 0.13 ​ $ 0.095 ​ $ 0.085 Second Quarter ​ $ 0.13 ​ $ 0.105 ​ $ 0.085 Third Quarter ​ $ 0.13 ​ $ 0.110 ​ $ 0.085 Fourth Quarter ​ $ 0.15 ​ $ 0.110 ​ $ 0.095 ​ The Company paid a total of approximately $32.6 million, $25.1 million and $20.5 million in cash dividends during 2021, 2020 and 2019, respectively. In January 2019, the Company’s board of directors declared four quarterly cash dividends of $0.085 per share to be paid to stockholders of record at the end of each quarter in 2019. In October 2019, the Company’s board of directors raised the cash dividends per share with the declaration of five cash dividends, consisting of (a) a dividend of $0.01 per share to be paid to stockholders of record at the end of the fourth quarter in 2019, that was in addition to the dividend of $0.085 per share to be paid to stockholders of record at the end of the fourth quarter in 2019 previously declared by the board in January 2019, and (b) a dividend of $0.095 per share to be paid to stockholders of record at the end of each quarter in 2020. In April 2020, the Company’s board of directors raised the cash dividends with the declaration of three cash dividends of $0.105 per share (in lieu of the $0.095 per share previously announced in October 2019) to be paid to stockholders of record at the end of each of the second, third and fourth quarter in 2020. In July 2020, the Company’s board of directors raised the cash dividends further with the declaration of two cash dividends of $0.11 per share (in lieu of the $0.105 per share announced in April 2020) to be paid to stockholders of record at the end of each of the third and fourth quarter in 2020. In January 2021, 2022 In January 2022, the Company’s board of directors raised the quarterly cash dividend by an additional $0.03 per share with the declaration of four cash dividends of $0.18 per share (in lieu of the $0.15 per share announced in October 2021) to be paid to stockholders of record at the end of each quarter in 2022. ​

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2021
Earnings Per Share Abstract
EARNINGS PER SHARE	10. EARNINGS PER SHARE: Basic earnings per share are calculated by dividing net income by the weighted-average shares of common stock outstanding during the period. Diluted earnings per share are calculated by dividing net income by the weighted-average shares of common stock and dilutive common equivalent shares outstanding during the period. Dilutive common equivalent shares included in this calculation consist of dilutive shares issuable upon the assumed exercise of outstanding common stock options, the assumed vesting of outstanding restricted stock units, the assumed issuance of awards under the stock purchase plan and contingently issuable performance-based awards, as computed using the treasury stock method. A summary of the earnings per share calculation is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands, except per share amounts) 2021 2020 2019 Basic earnings per share: ​ ​ ​ Net income ​ $ 164,413 ​ $ 71,176 ​ $ 193,468 Weighted-average common shares ​ 60,327 ​ 59,657 ​ 58,534 Basic earnings per share ​ $ 2.73 ​ $ 1.19 ​ $ 3.31 Diluted earnings per share: (1) ​ ​ ​ Net income ​ $ 164,413 ​ $ 71,176 ​ $ 193,468 Weighted-average common shares ​ 60,327 ​ 59,657 ​ 58,534 Effect of dilutive awards: ​ ​ ​ Employee stock plans ​ 1,140 ​ 1,188 ​ 1,098 Diluted weighted-average common shares ​ 61,467 ​ 60,845 ​ 59,632 Diluted earnings per share ​ $ 2.67 ​ $ 1.17 ​ $ 3.24 (1) The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has included in the 2021, 2020 and 2019 calculations those shares that were contingently issuable upon the satisfaction of the performance conditions as of the end of the respective periods. In the years ended December 31, 2021, 2020 and 2019, no outstanding stock awards were determined to be anti-dilutive and therefore were excluded from the computation of diluted earnings per share. In July 2020, the Company’s board of directors approved a two-for-one stock split in the form of a stock dividend, payable on August 18, 2020, to stockholders of record as of the close of business on August 14, 2020. The Company’s stockholders received one additional share of common stock for each share of common stock held on August 14, 2020

PROVISION FOR INCOME TAXES

PROVISION FOR INCOME TAXES	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure Abstract
PROVISION FOR INCOME TAXES	11. PROVISION FOR INCOME TAXES: Income Taxes The Company accounts for income taxes under the provisions of ASC 740, Income Taxes U.S. and foreign components of income (loss) before income taxes were: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 U.S. operations ​ $ 241 ​ $ (6,252) ​ $ 82,692 Foreign operations ​ 175,894 ​ 81,503 ​ 139,722 Total income before income taxes ​ $ 176,135 ​ $ 75,251 ​ $ 222,414 ​ The components of the provision for income taxes are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 Current provision (benefit): ​ ​ ​ Federal ​ $ 23,648 ​ $ 2,788 ​ $ 18,293 State ​ 2 ​ (181) ​ 184 Foreign ​ 1,608 ​ 1,677 ​ 1,293 ​ ​ 25,258 ​ 4,284 ​ 19,770 Deferred provision (benefit): ​ ​ ​ Federal ​ (11,449) ​ 348 ​ 9,683 State ​ — ​ — ​ — Foreign ​ (2,087) ​ (557) ​ (507) ​ ​ (13,536) ​ (209) ​ 9,176 Total ​ $ 11,722 ​ $ 4,075 ​ $ 28,946 ​ The provision for income taxes differs from the amount that would result by applying the applicable federal income tax rate to income before income taxes, as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 ​ 2019 Provision (benefit) computed at Federal statutory rate 21.0 % ​ 21.0 % ​ 21.0 % Business tax credits (3.6) ​ (7.4) ​ (2.4) ​ Stock-based compensation (0.6) ​ (0.1) ​ (0.2) ​ Foreign income taxed at different rate (23.8) ​ (22.0) ​ (12.7) ​ GILTI inclusion 13.1 ​ 10.7 ​ 6.2 ​ Valuation allowance 1.3 ​ 2.6 ​ 0.8 ​ Other (0.7) ​ 0.6 ​ 0.3 ​ Total 6.7 % ​ 5.4 % ​ 13.0 % ​ The Company’s effective tax rate is impacted by the geographic distribution of the Company’s world-wide earnings in lower-tax jurisdictions, federal research tax credits and the recognition of excess tax benefits related to share-based payments. These benefits were partially offset by foreign income subject to U.S. tax, known as global intangible low-taxed income. The Company’s primary jurisdiction where foreign earnings are derived is the Cayman Islands, which is a non-taxing jurisdiction. Income earned in other foreign jurisdictions was not material. The Company has not been granted any incentivized tax rates and does not operate under any tax holidays in any jurisdiction. The components of the net deferred income tax assets (liabilities) were as follows: ​ ​ ​ ​ ​ ​ ​ ​ December 31, (In thousands) ​ 2021 ​ 2020 Deferred tax assets: ​ ​ Other reserves and accruals ​ $ 17,193 ​ $ 3,707 Tax credit carry-forwards ​ 23,647 ​ 20,713 Stock compensation ​ 1,278 ​ 1,494 Capital losses ​ 159 ​ 158 Net operating loss ​ 2,370 ​ 2,303 Other ​ 692 ​ 1,023 Valuation allowance ​ (27,085) ​ (24,160) ​ ​ 18,254 ​ 5,238 Deferred tax liabilities: ​ ​ Depreciation ​ (1,750) ​ (1,974) ​ ​ (1,750) ​ (1,974) Net deferred tax assets ​ $ 16,504 ​ $ 3,264 ​ In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities and projected future taxable income. In the event that the Company determines, based on available evidence and management judgment, that all or part of the net deferred tax assets will not be realized in the future, the Company would record a valuation allowance in the period the determination is made. In addition, the calculation of tax liabilities involves significant judgment in estimating the impact of uncertainties in the application of complex tax laws. Resolution of these uncertainties in a manner inconsistent with the Company’s expectations could have a material impact on its results of operations and financial position. As of December 31, 2021, the Company continues to maintain a valuation allowance primarily as a result of capital losses for federal purposes, and on its California, New Jersey and Canada deferred tax assets as the Company believes that it is not more likely than not that the deferred tax assets will be fully realized. As of December 31, 2021, the Company had utilized all of its federal research and development tax credit carryforwards. As of December 31, 2021, the Company had California research and development tax credit carryforwards of approximately $33.9 million (there is no expiration of research and development tax credit carryforwards for the state of California) and California net operating losses of $45.6 million which will begin to expire in 2032 2030 2026 The Tax Act signed into law on December 22, 2017, generally allows companies to repatriate accumulated foreign earnings without incurring additional U.S. federal taxes beginning after December 31, 2017. Local foreign and U.S. states taxes may still be incurred upon repatriation. The Company has not provided for U.S. taxes on its undistributed earnings of foreign subsidiaries. The determination of the future tax consequences of the remittance of these earnings is not practicable. Unrecognized Tax Benefits The Company applies the provisions of ASC 740-10, relating to accounting for uncertain income taxes. Reconciliation of the beginning and ending amount of unrecognized tax benefits: ​ ​ ​ ​ ​ Unrecognized (In thousands) ​ Tax Benefits Unrecognized Tax Benefits Balance at January 1, 2019 ​ $ 18,607 Gross Increase for Tax Positions of Current Year ​ 1,379 Gross Decrease for Tax Positions of Prior Years ​ (937) Unrecognized Tax Benefits Balance at December 31, 2019 ​ 19,049 Gross Increase for Tax Positions of Current Year ​ 2,002 Gross Decrease for Tax Positions of Prior Years ​ — Unrecognized Tax Benefits Balance at December 31, 2020 ​ 21,051 Gross Increase for Tax Positions of Current Year ​ 2,068 Gross Decrease for Tax Positions of Prior Years ​ (1,756) Unrecognized Tax Benefits Balance at December 31, 2021 ​ $ 21,363 ​ The Company’s total unrecognized tax benefits as of December 31, 2021, 2020 and 2019, were $21.4 million, $21.1 million and $19.0 million, respectively. An income tax benefit of $10.6 million, net of valuation allowance adjustments, would be recorded if these unrecognized tax benefits are recognized. The Company cannot reasonably estimate the amount of the unrecognized tax benefit that could be adjusted in the next twelve months. The Company’s continuing practice is to recognize interest and/or penalties related to income tax matters in income tax expense. The Company had accrued interest and penalties of $0.8 million and $0.1 million as of December 31, 2021 and 2020, respectively, which have been recorded in long-term income taxes payable in the accompanying consolidated balance sheets. As of December 31, 2021, the Company has concluded all U.S. federal income tax matters for the years through 2012. However, due to tax attributes, the IRS may calculate tax adjustments for subsequent years for positions taken prior to 2012. As of December 31, 2021, the Company’s 2018 and 2019 tax years are under audit by the California Franchise Tax Board.

LEASES AND COMMITMENTS

LEASES AND COMMITMENTS	12 Months Ended
	Dec. 31, 2021
LEASES AND COMMITMENTS [Abstract]
LEASES AND COMMITMENTS	12. LEASES AND COMMITMENTS: Facilities and Leases The Company owns its main executive, administrative, manufacturing and technical offices in San Jose, California. The Company also owns a research and development facility in New Jersey, a design center in Germany and a multipurpose office building in Switzerland. The Company’s leases consist of operating leases for administrative office spaces, research-and-development facilities and sales offices in various countries around the world. The Company determines if an arrangement is a lease at inception. Some lease agreements contain lease and non-lease components, which are accounted for as a single lease component. Total lease expense was $3.3 million, $2.7 million and $2.5 million in the years ended December 31, 2021, 2020 and 2019, respectively, while short-term and variable lease expenses were not material during these periods. Balance sheet information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (In thousands) ​ Balance Sheet Classification ​ 2021 ​ 2020 Right-of-use assets ​ ​ ​ ​ ​ ​ Operating lease assets ​ Other assets ​ $ 11,887 ​ $ 10,295 ​ ​ ​ ​ ​ ​ ​ ​ ​ Lease liabilities ​ ​ ​ Current operating lease liabilities ​ Other accrued liabilities ​ $ 3,050 ​ $ 2,682 Non-current operating lease liabilities ​ Other liabilities ​ 8,371 ​ 7,345 Total ​ ​ ​ $ 11,421 ​ $ 10,027 ​ Initial lease terms are determined at commencement and may include options to extend or terminate the lease when it is reasonably certain the Company will exercise the option. Remaining lease terms range from one ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Lease term and discount rate ​ 2021 ​ 2020 Weighted average remaining lease term ​ 4.2 years ​ 4.2 years Weighted average discount rate 3.3 % ​ 3.3 % ​ Supplemental cash flows information related to leases was as follow: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 3,538 ​ $ 2,459 Right-of-use assets obtained in exchange for new operating lease obligations ​ $ 5,225 ​ $ 2,947 ​ Future minimum lease payments under all non-cancelable lease agreements as of December 31, 2021, are as follows: ​ ​ ​ ​ ​ December 31, (In thousands) ​ 2021 2022 ​ $ 3,472 2023 ​ 3,672 2024 ​ 2,294 2025 ​ 1,047 2026 ​ 669 Thereafter ​ 1,339 Total future minimum lease payments ​ 12,493 Less imputed interest ​ (1,072) Total ​ $ 11,421 ​ Purchase Obligations At December 31, 2021, the Company had no non-cancelable purchase obligations that were due beyond one year.

LEGAL PROCEEDINGS AND CONTINGEN

LEGAL PROCEEDINGS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure Abstract
LEGAL PROCEEDINGS AND CONTINGENCIES	13. LEGAL PROCEEDINGS AND CONTINGENCIES: From time to time in the ordinary course of business, the Company becomes involved in lawsuits, or customers and distributors may make claims against the Company. In accordance with ASC 450-10, Contingencies On April 1, 2016, Opticurrent, LLC filed a complaint against the Company in the United States District Court for the Eastern District of Texas alleging that the Company infringed one patent pertaining to transistor switch devices and seeking damages for the alleged infringement. The Company filed a motion to transfer the case to the Northern District of California, which the Court granted, and the case was assigned to a new judge in San Francisco following the transfer. On December 21, 2018, the Court granted the Company’s challenge to Opticurrent’s damages expert but denied the Company’s motion for summary judgment. Following a trial in February 2019, a jury issued a finding of direct infringement by the Company but found that the Company did not induce infringement, and awarded Opticurrent damages of $6.7 million. The Company challenged those findings in post-trial proceedings, and the Court granted one of the Company’s post-trial motions, reducing the damages award to $1.2 million. The Court of Appeals affirmed the original findings and the reduced damages award, but the Company believes Opticurrent made key disclaimers during reexamination proceedings after the original trial, giving rise to a motion to set aside the original judgment in view of a disclaimer, an issue that is currently on appeal to the Federal Circuit. Briefing and oral argument on the Company’s appeal are completed, with a ruling expected in the coming months. The District Court has issued an order staying execution on the original judgment pending the Company’s appeal, and the Federal Circuit rejected Opticurrent’s challenge to the order staying execution pending appeal. As such, the Company continues to believe it has strong defenses, and intends to continue to vigorously defend itself against Opticurrent’s claims. On June 19, 2019, Opticurrent, LLC filed a follow-on lawsuit in the United States District Court for the Northern District of California accusing more of the Company’s products of infringement and seeking damages for the alleged infringement of the same claim of the same patent asserted in the parties’ prior litigation, as described above. Limited discovery has taken place, but proceedings are currently stayed for all but written discovery; no schedule has yet been set for expert discovery, dispositive motions, or trial. The Company believes it has strong defenses, independent of the issue on appeal in the first case, and intends to vigorously defend itself against Opticurrent’s claims, with appeals to follow if necessary. On May 10, 2021, Opticurrent, LLC filed another follow-on lawsuit in the United States District Court for the Eastern District of Texas accusing one of the Company’s customers of infringement based on the use of the Company’s products and seeking damages for the alleged infringement of the same claim of the same patent asserted in the parties’ prior litigation, as described above. The case is at the pleadings stage, but the Company believes it has strong defenses, independent of the issue on appeal in the parties’ first case, and intends to vigorously defend against Opticurrent’s claims against the Company’s technology, with appeals to follow if necessary. On January 6, 2020, the Company filed a complaint against CogniPower LLC in the United States District Court for the District of Delaware for infringement of two of the Company’s patents and seeking a declaration of non-infringement with respect to patents that CogniPower had charged the Company’s customers with infringing , The Company is unable to predict the outcome of legal proceedings with certainty, and there can be no assurance that the Company will prevail in the above-mentioned unsettled litigations. These litigations, whether or not determined in the Company’s favor or settled, will be costly and will divert the efforts and attention of the Company’s management and technical personnel from normal business operations, potentially causing a material adverse effect on the business, financial condition and operating results. Currently, the Company is not able to estimate a loss or a range of loss for the ongoing litigation disclosed above, however adverse determinations in litigation could result in monetary losses, the loss of proprietary rights, subject the Company to significant liabilities, require the Company to seek licenses from third parties or prevent the Company from licensing the technology, any of which could have a material adverse effect on the Company’s business, financial condition and operating results.

RETIREMENT PLANS

RETIREMENT PLANS	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
RETIREMENT PLANS	14. RETIREMENT PLANS: The Company sponsors a defined benefit pension plan (Pension Plan) for its Swiss subsidiary in accordance with the legal requirements of Switzerland. The plan assets, which provide benefits in the event of an employee’s retirement, death or disability, are held in legally autonomous trustee-administered funds that are subject to Swiss law. Benefits are based on the employee’s age, years of service and salary, and the plan is financed by contributions by both the employee and the Company. The net periodic benefit cost of the Pension Plan was not material to the Company’s financial statements during the years ended December 31, 2021, 2020 and 2019. At December 31, 2021, the projected benefit obligation was $15.5 million, the plan assets were $9.5 million and the net pension liability was $6.0 million. As of December 31, 2020, the projected benefit obligation was $16.6 million, the plan assets were $9.7 million, and the net pension liability was $6.9 million. The Company has recorded the unfunded amount as a liability in its consolidated balance sheet at December 31, 2021 and 2020, under the other liabilities caption. The Company expects to make contributions to the Pension Plan of approximately $0.4 million during 2022. The unrealized actuarial loss on pension benefits, net of tax, at December 31, 2021, 2020 and 2019 was $0.7 million, $1.6 million and $2.5 million, respectively. These amounts were reflected in Note 3 under the caption accumulated other comprehensive loss. In accordance with the Compensation-Retirement Benefits Topic of ASC 715-20, Defined Benefits Plan

BANK LINE OF CREDIT

BANK LINE OF CREDIT	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
BANK LINE OF CREDIT	15. BANK LINE OF CREDIT: On July 27, 2016, the Company entered into a credit agreement with Wells Fargo Bank, National Association (the "Credit Agreement") that provides the Company with a $75.0 million revolving line of credit to use for general corporate purposes with a $20.0 million sub-limit for the issuance of standby and trade letters of credit. The Credit Agreement was amended on April 30, 2018, to extend the termination date from July 26, 2019, to April 30, 2022, with all other terms remaining the same. The Credit Agreement was amended on June 7, 2021, to provide an alternate borrowing rate as a replacement for LIBOR and extend the termination date from April 30, 2022, to June 7, 2026, with all other terms remaining the same. The Company’s ability to borrow under the revolving line of credit is conditioned upon the Company’s compliance with specified covenants, including reporting and financial covenants, primarily a minimum cash requirement and a debt to earnings ratio. The Credit Agreement terminates on June 7, 2026; all advances under the revolving line of credit will become due on such date, or earlier in the event of a default. The Company was compliant with all covenants and had no advances outstanding under the Credit Agreement as of December 31, 2021.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2021
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	Schedule II Valuation and Qualifying Accounts The Company maintains an allowance for the distributors’ ship and debit credits relating to the sell-through of the Company’s products. This reserve is established using the Company’s historical ship and debit amounts and levels of inventory in the distributor channels. The following is a summary of the activity in the allowance for ship and debit credits: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at Charged to ​ ​ ​ ​ ​ ​ Beginning of ​ Costs and ​ ​ ​ ​ Balance at End (In thousands) Period Expenses Deductions (1) of Period Allowance for ship and debit credits: ​ ​ ​ ​ ​ ​ ​ ​ Year ended December 31, 2019 ​ $ 40,118 ​ $ 230,278 ​ $ (236,921) ​ $ 33,475 Year ended December 31, 2020 ​ $ 33,475 ​ $ 257,765 ​ $ (264,805) ​ $ 26,435 Year ended December 31, 2021 ​ $ 26,435 ​ $ 311,443 ​ $ (296,279) ​ $ 41,599 (1) Deductions relate to ship and debit credits issued which adjust the sales price from the standard distribution price to the pre-approved lower price. Refer to Note 2, Significant Accounting Policies and Recent Accounting Pronouncements , for the Company’s revenue recognition policy, including the Company’s accounting for ship and debit claims.

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Segment Reporting	Segment Reporting The Company is organized and operates as one reportable segment, the design, development, manufacture and marketing of integrated circuits and related components for use primarily in the high-voltage power conversion markets. The Company’s chief operating decision maker, the Chief Executive Officer, reviews financial information presented on a consolidated basis for purposes of making operating decisions and assessing financial performance.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries after elimination of all intercompany transactions and balances.
Estimates	Estimates The preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. On an ongoing basis, the Company evaluates its estimates, including those related to revenue recognition, allowances for receivables, inventories, litigation and income taxes. These estimates are based on historical facts and various other factors, which the Company believes to be reasonable at the time the estimates are made. However, as the effects of future events cannot be determined with precision, actual results could differ significantly from management’s estimates.
Revenue Recognition	Revenue Recognition The Company applies the provisions of Accounting Standards Codification (ASC) 606-10, Revenue from Contracts with Customers the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when a performance obligation is satisfied. Product revenues consist of sales to original equipment manufacturers, or OEMs, merchant power supply manufacturers and distributors. The Company considers customer purchase orders, which in some cases are governed by master sales agreements, to be the contracts with a customer. In situations where sales are to a distributor, the Company has concluded that its contracts are with the distributor as the Company holds a contract bearing enforceable rights and obligations only with the distributor. As part of its consideration of the contract, the Company evaluates certain factors including the customer’s ability to pay (or credit risk). For each contract, the Company considers the promise to transfer products, each of which is distinct, to be the identified performance obligations. In determining the transaction price the Company evaluates whether the price is subject to refund or adjustment to determine the net consideration to which the Company expects to be entitled. As the Company’s standard payment terms are less than one year, the Company has elected the practical expedient under ASC 606-10-32-18 to not assess whether a contract has a significant financing component. The Company allocates the transaction price to each distinct product based on their relative standalone selling price. The product price as specified on the purchase order is considered the standalone selling price as it is an observable input which depicts the price as if sold to a similar customer in similar circumstances. Revenue is recognized when control of the product is transferred to the customer (i.e., when the Company’s performance obligation is satisfied), which typically occurs at shipment. Further, in determining whether control has transferred, the Company considers if there is a present right to payment and legal title, along with risks and rewards of ownership having transferred to the customer. Frequently, the Company receives orders for products to be delivered over multiple dates that may extend across several reporting periods. The Company invoices for each delivery upon shipment and recognizes revenues for each distinct product delivered, assuming transfer of control has occurred. As scheduled delivery dates are within one year, under the optional exemption provided by ASC 606-10-50-14 revenues allocated to future shipments of partially completed contracts are not disclosed. The Company has also elected the practical expedient under ASC 340-40-25-4 to expense commissions when incurred as the amortization period of the commission asset the Company would have otherwise recognized is less than one year. Sales to international customers that are shipped from the Company’s facility outside of the United States are pursuant to EX Works, or EXW, shipping terms, meaning that control of the product transfers to the customer upon shipment from the Company’s foreign warehouse. Sales to international customers that are shipped from the Company’s facility in California are pursuant to Delivered at Frontier, or DAF, shipping terms. As such, control of the product passes to the customer when the shipment reaches the destination country and revenue is recognized upon the arrival of the product in that country. Shipments to customers in the Americas are pursuant to Free on Board, or FOB, point of origin shipping terms meaning that control is passed to the customer upon shipment. Sales to most distributors are made under terms allowing certain price adjustments and limited rights of return (known as “stock rotation”) of the Company’s products held in their inventory or upon sale to their end customers. Revenue from sales to distributors is recognized upon the transfer of control to the distributor. Frequently, distributors need to sell at a price lower than the standard distribution price in order to win business. At the time the distributor invoices its customer or soon thereafter, the distributor submits a “ship and debit” price adjustment claim to the Company to adjust the distributor’s cost from the standard price to the pre-approved lower price. After the Company verifies that the claim was pre-approved, a credit memo is issued to the distributor for the ship and debit claim. In determining the transaction price, the Company considers ship and debit price adjustments to be variable consideration. Such price adjustments are estimated using the expected value method based on an analysis of actual ship and debit claims, at the distributor and product level, over a period of time considered adequate to account for current pricing and business trends. Historically, actual price adjustments for ship and debit claims relative to those estimated and included when determining the transaction price have not materially differed. Stock rotation rights grant the distributor the ability to return certain specified amounts of inventory. Stock rotation adjustments are an additional form of variable consideration and are also estimated using the expected value method based on historical return rates. Historically, distributor stock rotation adjustments have not been material. Sales to certain distributors are made under terms that do not include rights of return or price concessions after the product is shipped to the distributor. Accordingly, upon application of steps one through five above, product revenue is recognized upon shipment and transfer of control. The Company generally provides an assurance warranty that its products will substantially conform to the published specifications for twelve months from the date of shipment. The Company’s liability is limited to either a credit equal to the purchase price or replacement of the defective part. Returns under warranty have historically been immaterial. As such, the Company does not record a specific warranty reserve or consider activities related to such warranty, if any, to be a separate performance obligation.
Inventories	Inventories Inventories (which consist of costs associated with the purchases of wafers from domestic and offshore foundries and of packaged components from offshore assembly manufacturers, as well as internal labor and overhead associated with the testing of both wafers and packaged components) are stated at the lower of cost (first-in, first-out) or market. Provisions, when required, are made to reduce inventories to their estimated net realizable values.
Income Taxes	Income Taxes Income-tax expense is an estimate of current income taxes payable or refundable in the current fiscal year based on reported income before income taxes. Deferred income taxes reflect the effect of temporary differences and carry-forwards that are recognized for financial reporting and income tax purposes. The Company accounts for income taxes under the provisions of ASC 740, Income Taxe
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill and the Company’s domain name are evaluated in accordance with ASC 350-10, Goodwill and Other Intangible Assets, In accordance with ASC 360-10, Accounting for the Impairment or Disposal of Long-Lived Assets
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers cash invested in highly liquid financial instruments with maturities of three months or less at the date of purchase to be cash equivalents.
Marketable Securities	Marketable Securities The Company generally holds securities until maturity; however, they may be sold under certain circumstances including, but not limited to, when necessary for the funding of acquisitions and other strategic investments. As a result, the Company classifies its investment portfolio as available-for-sale. The Company classifies all investments with a maturity date greater than three months at the date of purchase as short-term marketable securities in its consolidated balance sheet. As of December 31, 2021 and 2020, the Company’s marketable securities consisted primarily of commercial paper, corporate bonds, government securities and/or other high-quality commercial securities.
Employee Benefits Plan	Employee Benefits Plan The Company sponsors a 401(k) tax-deferred savings plan for all employees in the United States who meet certain eligibility requirements. Participants may contribute up to the amount allowable as a deduction for federal income tax purposes. The Company is not required to contribute; however, the Company contributes a certain percentage of employee annual salaries on a discretionary basis, not to exceed an established threshold. The Company provided for a contribution of approximately $1.9 million, $1.8 million and $1.4 million in 2021, 2020 and 2019, respectively.
Retirement Benefit Obligations (Pension)	Retirement Benefit Obligations (Pension) The Company recognizes the over-funded or under-funded status of a defined benefit pension or post-retirement plan as an asset or liability in the accompanying consolidated balance sheets. Actuarial gains and losses are recorded in accumulated other comprehensive loss, a component of stockholders’ equity, and are amortized as a component of net periodic cost over the remaining estimated service period of participants.
Foreign Currency Risk and Foreign Currency Translation	Foreign Currency Risk and Foreign Currency Translation As of December 31, 2021, the Company’s primary transactional currency was U.S. dollars; in addition, the Company holds cash in Swiss francs and euros to fund the operations of the Company’s Swiss subsidiary. The foreign exchange rate fluctuation between the U.S. dollar versus the Swiss franc and euro is recorded in other income in the consolidated statements of income. Gains and losses arising from the remeasurement of non-functional currency balances are recorded in other income in the accompanying consolidated statements of income. The Company realized a foreign exchange transaction loss of $0.6 million, $0.5 million and $0.3 million in 2021, 2020 and 2019 respectively. The functional currencies of the Company’s other subsidiaries are the local currencies. Accordingly, all assets and liabilities are translated into U.S. dollars at the current exchange rates as of the applicable balance sheet date. Revenues and expenses are translated at the average exchange rate prevailing during the period. Cumulative gains and losses from the translation of the foreign subsidiaries’ financial statements have been included accumulated other comprehensive loss in stockholders’ equity.
Warranty	Warranty The Company generally warrants that its products will substantially conform to the published specifications for 12 months
Advertising	Advertising Advertising costs are expensed as incurred and amounted to $1.3 million, $1.2 million and $1.4 million in 2021, 2020 and 2019, respectively.
Research and Development	Research and Development Research and development costs are expensed as incurred.
Indemnifications	Indemnifications The Company sells products to its distributors under contracts, collectively referred to as Distributor Sales Agreements (DSA). Each DSA contains the relevant terms of the contractual arrangement with the distributor, and generally includes certain provisions for indemnifying the distributor against losses, expenses, and liabilities from damages that may be awarded against the distributor in the event the Company’s products are found to infringe upon a patent, copyright, trademark, or other proprietary right of a third party (Customer Indemnification). The DSA generally limits the scope of and remedies for the Customer Indemnification obligations in a variety of industry-standard respects, including, but not limited to, limitations based on time and geography, and a right to replace an infringing product. The Company also, from time to time, has granted a specific indemnification right to individual customers. The Company believes its internal development processes and other policies and practices limit its exposure related to such indemnifications. In addition, the Company requires its employees to sign a proprietary information and inventions agreement, which assigns the rights to its employees’ development work to the Company. To date, the Company has not had to reimburse any of its distributors or customers for any losses related to these indemnifications and no material claims were outstanding as of December 31, 2021. For several reasons, including the lack of prior indemnification claims and the lack of a monetary liability limit for certain infringement cases, the Company cannot determine the maximum amount of potential future payments, if any, related to such indemnifications.
Recent Accounting Pronouncements	Recent Accounting Pronouncements The Company has considered all recent accounting pronouncements issued, but not yet effective, and does not expect any to have a material effect on the Company’s condensed consolidated financial statements.

FAIR VALUE MEASUREMENTS (Polici

FAIR VALUE MEASUREMENTS (Policies)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures Abstract
Fair Value of Financial Instruments	The Company’s cash equivalents and investment instruments are classified within Level 1 or Level 2 of the fair-value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. The type of instrument valued based on quoted market prices in active markets primarily includes money market securities. This type of instrument is generally classified within Level 1 of the fair-value hierarchy. The types of instruments valued based on other observable inputs (Level 2 of the fair-value hierarchy) include investment-grade corporate bonds and commercial paper. Such types of investments are valued by using a multi-dimensional relational model, the inputs are primarily benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications.

STOCK PLANS AND SHARE BASED C_2

STOCK PLANS AND SHARE BASED COMPENSATION (Policies)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company applies the provisions of ASC 718-10, Stock Compensation

COMPONENTS OF THE COMPANY'S C_2

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Tables)	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures Abstract
Schedule of Accounts Receivable	Accounts Receivable ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Accounts receivable trade ​ $ 87,503 ​ $ 66,703 Allowance for ship and debit ​ (41,599) ​ (26,435) Allowance for stock rotation and rebate ​ (4,066) ​ (3,931) Allowance for credit losses ​ ​ (445) ​ ​ (427) Total ​ $ 41,393 ​ $ 35,910
Schedule of Allowance for Credit Losses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, (In thousands) ​ 2021 2020 Beginning balance ​ $ (427) ​ $ (763) Provision for credit loss expense ​ (1,023) ​ (621) Receivables written off ​ 74 ​ 198 Recoveries collected ​ 931 ​ 759 Ending balance ​ $ (445) ​ $ (427)
Schedule of Inventory, Current	Inventories ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Raw materials ​ $ 24,131 ​ $ 32,131 Work-in-process ​ 31,788 ​ 39,469 Finished goods ​ 43,347 ​ 31,278 Total ​ $ 99,266 ​ $ 102,878
Property and Equipment	Property and Equipment ​ ​ ​ ​ ​ ​ ​ ​ December 31, December 31, (In thousands) ​ 2021 ​ 2020 Land ​ $ 22,187 ​ $ 22,189 Construction-in-progress ​ 22,661 ​ 34,886 Building and improvements ​ 81,027 ​ 64,808 Machinery and equipment ​ 235,066 ​ 202,698 Computer software and hardware and office furniture and fixtures ​ 57,926 ​ 55,591 Total ​ 418,867 ​ 380,172 Less: Accumulated depreciation ​ (239,043) ​ (213,984) Property and equipment, net ​ $ 179,824 ​ $ 166,188
Property and Equipment Useful Lives	​ ​ ​ ​ ​ ​ Building and improvements ​ ​ 4 - 40 years Machinery and equipment ​ 2 - 8 years Computer software and hardware and office furniture and fixtures ​ 4 - 7 years
Schedule of Accumulated Other Comprehensive Loss	Changes in accumulated other comprehensive loss for the three years ended December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized Gains ​ ​ ​ ​ ​ ​ ​ ​ and Losses on ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ Available-for-Sale ​ Defined Benefit ​ Currency ​ ​ ​ (In thousands) ​ Securities ​ Pension Items ​ Items ​ Total Balance at January 1, 2019 ​ $ (266) ​ $ (712) ​ $ (711) ​ $ (1,689) Other comprehensive income (loss) before reclassifications ​ 849 ​ (1,839) ​ (518) ​ (1,508) Amounts reclassified from accumulated other comprehensive loss ​ — ​ 67 (1) — ​ 67 Other comprehensive loss ​ 849 ​ (1,772) ​ (518) ​ (1,441) Balance at December 31, 2019 ​ 583 ​ (2,484) ​ (1,229) ​ (3,130) Other comprehensive income (loss) before reclassifications ​ 307 ​ 636 ​ (183) ​ 760 Amounts reclassified from accumulated other comprehensive loss ​ — ​ 207 (1) — ​ 207 Other comprehensive income ​ 307 ​ 843 ​ (183) ​ 967 Balance at December 31, 2020 ​ 890 ​ (1,641) ​ (1,412) ​ (2,163) Other comprehensive income (loss) before reclassifications ​ (2,055) ​ 800 ​ (486) ​ (1,741) Amounts reclassified from accumulated other comprehensive loss ​ — ​ 167 (1) — ​ 167 Other comprehensive loss ​ (2,055) ​ 967 ​ (486) ​ (1,574) Balance at December 31, 2021 ​ $ (1,165) ​ $ (674) ​ $ (1,898) ​ $ (3,737) (1) This component of accumulated other comprehensive loss is included in the computation of net periodic pension cost for the years ended December 31, 2021, 2020 and 2019.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures Abstract
Fair Value of Cash Equivalents and Marketable Securities	The fair value hierarchy of the Company’s cash equivalents and marketable securities at December 31, 2021, and 2020, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2021 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 172,237 ​ $ — ​ $ 172,237 Corporate securities ​ ​ 282,540 ​ ​ — ​ ​ 282,540 Money market funds ​ 29,793 ​ 29,793 ​ — Total ​ $ 484,570 ​ $ 29,793 ​ $ 454,777 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurement at ​ ​ December 31, 2020 ​ ​ ​ Quoted Prices in ​ ​ ​ ​ ​ ​ ​ Active Markets for ​ Significant Other ​ ​ ​ ​ ​ Identical Assets ​ Observable Inputs (In thousands) ​ Total Fair Value ​ (Level 1) ​ (Level 2) Commercial paper ​ $ 253,855 ​ $ — ​ $ 253,855 Corporate securities ​ ​ 146,658 ​ ​ — ​ ​ 146,658 Money market funds ​ 1,634 ​ 1,634 ​ — Total ​ $ 402,147 ​ $ 1,634 ​ $ 400,513

MARKETABLE SECURITIES (Tables)

MARKETABLE SECURITIES (Tables)	12 Months Ended
	Dec. 31, 2021
Marketable Securities Abstract
Available-for-sale Securities	Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2021, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 89,965 ​ $ — ​ $ — ​ $ 89,965 Corporate securities ​ ​ 7,285 ​ ​ — ​ ​ (3) ​ ​ 7,282 Total ​ 97,250 ​ — ​ (3) ​ 97,247 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 25,054 ​ — ​ (42) ​ 25,012 Total ​ 25,054 ​ — ​ (42) ​ 25,012 Investments due in 12 months or greater: ​ ​ ​ ​ Corporate securities ​ 251,096 ​ 21 ​ (1,141) ​ 249,976 Total ​ ​ 251,096 ​ 21 ​ ​ (1,141) ​ 249,976 Total marketable securities ​ $ 373,400 ​ $ 21 ​ $ (1,186) ​ $ 372,235 ​ Amortized cost and estimated fair market value of marketable securities classified as available-for-sale (excluding cash equivalents) at December 31, 2020, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Gross Unrealized ​ Estimated Fair (In thousands) Cost Gains Losses Market Value Investments due in 3 months or less: ​ ​ ​ ​ Commercial paper ​ $ 43,660 ​ $ — ​ $ — ​ $ 43,660 Corporate securities ​ ​ 19,846 ​ ​ 44 ​ ​ — ​ ​ 19,890 Total ​ 63,506 ​ 44 ​ — ​ 63,550 Investments due in 4-12 months: ​ ​ ​ ​ Corporate securities ​ 125,922 ​ 846 ​ — ​ 126,768 Total ​ 125,922 ​ 846 ​ — ​ 126,768 Total marketable securities ​ $ 189,428 ​ $ 890 ​ $ — ​ $ 190,318 ​
Available-for-sale Securities in an Unrealized Loss Position	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Less Than 12 Months ​ 12 Months or Longer ​ Total ​ Estimated Gross Estimated Gross Estimated Gross ​ ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized ​ Fair Market ​ Unrealized (In thousands) ​ Value ​ Losses ​ Value ​ Losses ​ Value ​ Losses Corporate securities ​ $ 274,380 ​ $ (1,186) ​ $ — ​ $ — ​ $ 274,380 ​ $ (1,186) Total marketable securities ​ $ 274,380 ​ $ (1,186) ​ $ — ​ $ — ​ $ 274,380 ​ $ (1,186)

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule Of Intangible Assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2021 ​ December 31, 2020 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ (In thousands) ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Domain name ​ $ 1,261 ​ $ — ​ $ 1,261 ​ $ 1,261 ​ $ — ​ $ 1,261 Developed technology ​ 37,960 ​ (31,603) ​ 6,357 ​ 37,960 ​ (29,126) ​ 8,834 Customer relationships ​ 16,700 ​ (16,458) ​ 242 ​ 16,700 ​ (15,687) ​ 1,013 Technology licenses ​ 1,926 ​ (774) ​ 1,152 ​ 1,926 ​ (528) ​ 1,398 Total intangible assets ​ $ 57,847 ​ $ (48,835) ​ $ 9,012 ​ $ 57,847 ​ $ (45,341) ​ $ 12,506
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated future amortization expense related to definite-lived intangible assets at December 31, 2021, is as follows: ​ ​ ​ ​ ​ Estimated ​ ​ Amortization Fiscal Year ​ (In thousands) 2022 ​ $ 2,415 2023 ​ 2,173 2024 ​ 1,279 2025 ​ 832 2026 ​ 687 Thereafter ​ 365 Total ​ $ 7,751

STOCK PLANS AND SHARE BASED C_3

STOCK PLANS AND SHARE BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based Compensation Expense	The following table summarizes the stock-based compensation expense recognized in accordance with ASC 718-10 for the years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 Cost of revenues ​ $ 2,359 ​ $ 1,963 ​ $ 1,237 Research and development ​ 12,127 ​ 10,378 ​ 8,423 Sales and marketing ​ 7,630 ​ 6,290 ​ 5,015 General and administrative ​ 15,493 ​ 12,281 ​ 8,672 Total stock-based compensation expense ​ $ 37,609 ​ $ 30,912 ​ $ 23,347
Share-based Payment Arrangement, Nonvested Award, Cost	The following table summarizes total compensation expense related to unvested awards not yet recognized, net of expected forfeitures, and the weighted average period over which it is expected to be recognized as of December 31, 2021: ​ ​ ​ ​ ​ ​ ​ Unrecognized Compensation Weighted Average ​ ​ Expense for Unvested ​ Remaining Recognition ​ ​ Awards ​ Period ​ ​ (In thousands) ​ (In years) Long-term performance-based awards ​ $ 7,474 1.19 Restricted stock units ​ 35,707 2.26 Purchase plan ​ 174 0.08 Total unrecognized compensation expense ​ $ 43,355
Fair value assumptions for employees' stock purchase rights under the Purchase Plan	The fair value of employees’ stock purchase rights under the Purchase Plan was estimated using the Black-Scholes model with the following weighted-average assumptions used during the three years ended December 31, 2021, 2020 and 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2021 ​ 2020 ​ 2019 Risk-free interest rates ​ 0.07 % ​ ​ 0.90 % ​ ​ 2.28 % Expected volatility rates ​ 41 % ​ ​ 47 % ​ ​ 37 % Expected dividend yield ​ 0.57 % ​ ​ 0.78 % ​ ​ 0.91 % Expected term of purchase rights (in years) ​ 0.50 ​ ​ 0.50 ​ ​ 0.50 Weighted-average estimated fair value of purchase rights ​ $ 23.92 ​ ​ $ 15.73 ​ ​ $ 19.39 ​
Summary of Option Activity Under the Plans	A summary of stock options outstanding as of December 31, 2021, and activity during three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Exercise ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Price (In years) (In thousands) Outstanding at January 1, 2019 670 ​ $ 16.21 ​ Granted — ​ — ​ Exercised (335) ​ $ 12.98 ​ Forfeited or expired — ​ — ​ Outstanding at December 31, 2019 335 ​ $ 19.44 ​ Granted — ​ — ​ Exercised (243) ​ $ 18.99 ​ Forfeited or expired — ​ — ​ Outstanding at December 31, 2020 92 ​ $ 20.63 ​ Granted — ​ ​ — ​ Exercised (80) ​ $ 20.50 ​ Forfeited or expired — ​ ​ — ​ Outstanding at December 31, 2021 12 ​ $ 21.44 0.35 ​ $ 857 Vested and Exercisable at December 31, 2021 12 ​ ​ ​ 0.35 ​ $ 857
Summary of stock options outstanding by exercise price range	The following table summarizes the stock options outstanding at December 31, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options Outstanding ​ Options Exercisable ​ ​ Weighted Average Weighted ​ Weighted ​ ​ ​ ​ Remaining ​ Average ​ ​ ​ Average (Shares in thousands) ​ Options ​ Contractual Term ​ Exercise ​ Options ​ Exercise Range of Exercise Prices ​ Outstanding ​ (In years) ​ Price ​ Exercisable ​ Price $21.44 - $21.44 12 0.35 ​ $ 21.44 12 ​ $ 21.44
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of RSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 1,790 ​ $ 29.10 ​ Granted 582 ​ $ 34.90 ​ Vested (603) ​ $ 28.10 ​ Forfeited (50) ​ $ 31.72 ​ Outstanding at December 31, 2019 1,719 ​ $ 31.33 ​ Granted 439 ​ $ 44.82 ​ Vested (599) ​ $ 30.25 ​ Forfeited (41) ​ $ 36.77 ​ Outstanding at December 31, 2020 1,518 ​ $ 35.51 ​ Granted 271 ​ $ 83.79 ​ Vested (546) ​ $ 35.03 ​ Forfeited (99) ​ $ 39.85 ​ Outstanding at December 31, 2021 1,144 ​ $ 46.81 1.25 ​ $ 106,306 Outstanding and expected to vest at December 31, 2021 1,081 ​ ​ ​ 1.20 ​ $ 100,433
Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of performance-based awards outstanding	A summary of PSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ Weighted- ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Intrinsic Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 52 ​ $ 31.44 ​ Granted 185 ​ $ 35.06 ​ Vested (52) ​ $ 31.44 ​ Forfeited or canceled (64) ​ $ 35.06 ​ Outstanding at December 31, 2019 121 ​ $ 35.06 ​ Granted 150 ​ $ 46.31 ​ Vested (121) ​ $ 35.06 ​ Forfeited or canceled — ​ ​ — ​ Outstanding at December 31, 2020 150 ​ $ 46.27 ​ Granted 105 ​ $ 84.48 ​ Vested (150) ​ $ 46.27 ​ Forfeited or canceled (1) ​ $ 85.01 ​ Outstanding at December 31, 2021 104 ​ $ 84.47 — ​ $ 9,701 Outstanding and expected to vest at December 31, 2021 104 ​ ​ ​ — ​ $ 9,701
Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of performance-based awards outstanding	A summary of PRSU awards outstanding as of December 31, 2021, and activity during the three years then ended, is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-Average ​ Aggregate ​ ​ ​ ​ Weighted-Average ​ Remaining ​ Intrinsic ​ ​ Shares ​ Grant Date Fair ​ Contractual Term ​ Value ​ (In thousands) Value Per Share (In years) (In thousands) Outstanding at January 1, 2019 426 ​ $ 27.74 ​ Granted 144 ​ $ 34.09 ​ Vested (140) ​ $ 21.63 ​ Forfeited or canceled (143) ​ $ 31.50 ​ Outstanding at December 31, 2019 287 ​ $ 32.03 ​ ​ Granted 152 ​ $ 49.67 ​ Vested — ​ ​ — ​ Forfeited or canceled (138) ​ $ 29.95 ​ Outstanding at December 31, 2020 301 ​ $ 41.90 ​ Granted 103 ​ $ 82.92 ​ Vested (6) ​ $ 29.94 ​ Forfeited or canceled (15) ​ $ 40.05 ​ Outstanding at December 31, 2021 383 ​ $ 53.14 0.92 ​ $ 35,537 Outstanding and expected to vest at December 31, 2021 383 ​ ​ ​ 0.92 ​ $ 35,537

SIGNIFICANT CUSTOMERS AND GEO_2

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES (Tables)	12 Months Ended
	Dec. 31, 2021
Concentration Risk [Line Items]
Geographic Net Revenues	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 United States of America ​ $ 17,238 ​ $ 11,065 ​ $ 10,662 Hong Kong/China ​ 446,980 ​ 306,938 ​ 237,341 Taiwan ​ 25,991 ​ 21,650 ​ 36,297 Korea ​ 59,501 ​ 40,059 ​ 30,395 Western Europe (excluding Germany) ​ 35,835 ​ 33,564 ​ 36,025 Japan ​ 25,101 ​ 17,453 ​ 15,496 Germany ​ 32,664 ​ 23,242 ​ 20,197 Other ​ 59,967 ​ 34,347 ​ 34,256 Total net revenues ​ $ 703,277 ​ $ 488,318 ​ $ 420,669
Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Schedules of Concentration of Risk, by Risk Factor	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Customer 2021 ​ 2020 ​ 2019 Avnet ​ 30 % ​ 19 % ​ 11 % Honestar Technologies Co., Ltd. 16 % ​ 11 % ​ * ​ *Total customer revenue was less than 10% of net revenues.
Accounts Receivable [Member]
Concentration Risk [Line Items]
Schedules of Concentration of Risk, by Risk Factor	The following customers represented 10% or more of accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Customer 2021 ​ 2020 Avnet ​ 45 % ​ 50 % Powertech Distribution Ltd. * % ​ 10 %

COMMON STOCK REPURCHASES AND _2

COMMON STOCK REPURCHASES AND CASH DIVIDENDS (Tables)	12 Months Ended
	Dec. 31, 2021
Equity Abstract
Schedule of Dividends Declared and Paid	The following table presents the quarterly dividends declared per share of the Company’s common stock for the periods indicated: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 2020 2019 First Quarter ​ $ 0.13 ​ $ 0.095 ​ $ 0.085 Second Quarter ​ $ 0.13 ​ $ 0.105 ​ $ 0.085 Third Quarter ​ $ 0.13 ​ $ 0.110 ​ $ 0.085 Fourth Quarter ​ $ 0.15 ​ $ 0.110 ​ $ 0.095

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share Abstract
Earnings per share calculation	A summary of the earnings per share calculation is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands, except per share amounts) 2021 2020 2019 Basic earnings per share: ​ ​ ​ Net income ​ $ 164,413 ​ $ 71,176 ​ $ 193,468 Weighted-average common shares ​ 60,327 ​ 59,657 ​ 58,534 Basic earnings per share ​ $ 2.73 ​ $ 1.19 ​ $ 3.31 Diluted earnings per share: (1) ​ ​ ​ Net income ​ $ 164,413 ​ $ 71,176 ​ $ 193,468 Weighted-average common shares ​ 60,327 ​ 59,657 ​ 58,534 Effect of dilutive awards: ​ ​ ​ Employee stock plans ​ 1,140 ​ 1,188 ​ 1,098 Diluted weighted-average common shares ​ 61,467 ​ 60,845 ​ 59,632 Diluted earnings per share ​ $ 2.67 ​ $ 1.17 ​ $ 3.24 (1) The Company includes the shares underlying performance-based awards in the calculation of diluted earnings per share if the performance conditions have been satisfied as of the end of the reporting period and excludes such shares when the necessary conditions have not been met. The Company has included in the 2021, 2020 and 2019 calculations those shares that were contingently issuable upon the satisfaction of the performance conditions as of the end of the respective periods.

PROVISION FOR INCOME TAXES (Tab

PROVISION FOR INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure Abstract
U.S. and foreign components of income (loss) before income taxes	U.S. and foreign components of income (loss) before income taxes were: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 U.S. operations ​ $ 241 ​ $ (6,252) ​ $ 82,692 Foreign operations ​ 175,894 ​ 81,503 ​ 139,722 Total income before income taxes ​ $ 176,135 ​ $ 75,251 ​ $ 222,414
Components of provision for income taxes	The components of the provision for income taxes are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) 2021 2020 2019 Current provision (benefit): ​ ​ ​ Federal ​ $ 23,648 ​ $ 2,788 ​ $ 18,293 State ​ 2 ​ (181) ​ 184 Foreign ​ 1,608 ​ 1,677 ​ 1,293 ​ ​ 25,258 ​ 4,284 ​ 19,770 Deferred provision (benefit): ​ ​ ​ Federal ​ (11,449) ​ 348 ​ 9,683 State ​ — ​ — ​ — Foreign ​ (2,087) ​ (557) ​ (507) ​ ​ (13,536) ​ (209) ​ 9,176 Total ​ $ 11,722 ​ $ 4,075 ​ $ 28,946 ​
Effective income tax rate reconciliation	The provision for income taxes differs from the amount that would result by applying the applicable federal income tax rate to income before income taxes, as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ ​ 2021 ​ 2020 ​ 2019 Provision (benefit) computed at Federal statutory rate 21.0 % ​ 21.0 % ​ 21.0 % Business tax credits (3.6) ​ (7.4) ​ (2.4) ​ Stock-based compensation (0.6) ​ (0.1) ​ (0.2) ​ Foreign income taxed at different rate (23.8) ​ (22.0) ​ (12.7) ​ GILTI inclusion 13.1 ​ 10.7 ​ 6.2 ​ Valuation allowance 1.3 ​ 2.6 ​ 0.8 ​ Other (0.7) ​ 0.6 ​ 0.3 ​ Total 6.7 % ​ 5.4 % ​ 13.0 %
Components of net deferred income tax assets (liabilities)	The components of the net deferred income tax assets (liabilities) were as follows: ​ ​ ​ ​ ​ ​ ​ ​ December 31, (In thousands) ​ 2021 ​ 2020 Deferred tax assets: ​ ​ Other reserves and accruals ​ $ 17,193 ​ $ 3,707 Tax credit carry-forwards ​ 23,647 ​ 20,713 Stock compensation ​ 1,278 ​ 1,494 Capital losses ​ 159 ​ 158 Net operating loss ​ 2,370 ​ 2,303 Other ​ 692 ​ 1,023 Valuation allowance ​ (27,085) ​ (24,160) ​ ​ 18,254 ​ 5,238 Deferred tax liabilities: ​ ​ Depreciation ​ (1,750) ​ (1,974) ​ ​ (1,750) ​ (1,974) Net deferred tax assets ​ $ 16,504 ​ $ 3,264 ​
Unrecognized tax benefits rollforward	The Company applies the provisions of ASC 740-10, relating to accounting for uncertain income taxes. Reconciliation of the beginning and ending amount of unrecognized tax benefits: ​ ​ ​ ​ ​ Unrecognized (In thousands) ​ Tax Benefits Unrecognized Tax Benefits Balance at January 1, 2019 ​ $ 18,607 Gross Increase for Tax Positions of Current Year ​ 1,379 Gross Decrease for Tax Positions of Prior Years ​ (937) Unrecognized Tax Benefits Balance at December 31, 2019 ​ 19,049 Gross Increase for Tax Positions of Current Year ​ 2,002 Gross Decrease for Tax Positions of Prior Years ​ — Unrecognized Tax Benefits Balance at December 31, 2020 ​ 21,051 Gross Increase for Tax Positions of Current Year ​ 2,068 Gross Decrease for Tax Positions of Prior Years ​ (1,756) Unrecognized Tax Benefits Balance at December 31, 2021 ​ $ 21,363

LEASES AND COMMITMENTS (Tables)

LEASES AND COMMITMENTS (Tables)	12 Months Ended
	Dec. 31, 2021
LEASES AND COMMITMENTS [Abstract]
Supplemental Balance Sheet Information of Operating Leases	Balance sheet information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, (In thousands) ​ Balance Sheet Classification ​ 2021 ​ 2020 Right-of-use assets ​ ​ ​ ​ ​ ​ Operating lease assets ​ Other assets ​ $ 11,887 ​ $ 10,295 ​ ​ ​ ​ ​ ​ ​ ​ ​ Lease liabilities ​ ​ ​ Current operating lease liabilities ​ Other accrued liabilities ​ $ 3,050 ​ $ 2,682 Non-current operating lease liabilities ​ Other liabilities ​ 8,371 ​ 7,345 Total ​ ​ ​ $ 11,421 ​ $ 10,027
Lease Terms and Discount Rate	​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ December 31, Lease term and discount rate ​ 2021 ​ 2020 Weighted average remaining lease term ​ 4.2 years ​ 4.2 years Weighted average discount rate 3.3 % ​ 3.3 %
Supplemental Cash Flow Information Related to Leases	Supplemental cash flows information related to leases was as follow: ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, (In thousands) ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 3,538 ​ $ 2,459 Right-of-use assets obtained in exchange for new operating lease obligations ​ $ 5,225 ​ $ 2,947
Lessee, Operating Lease, Liability, Maturity	Future minimum lease payments under all non-cancelable lease agreements as of December 31, 2021, are as follows: ​ ​ ​ ​ ​ December 31, (In thousands) ​ 2021 2022 ​ $ 3,472 2023 ​ 3,672 2024 ​ 2,294 2025 ​ 1,047 2026 ​ 669 Thereafter ​ 1,339 Total future minimum lease payments ​ 12,493 Less imputed interest ​ (1,072) Total ​ $ 11,421

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Segment Reporting) (Details)	12 Months Ended
	Dec. 31, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	1

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS (Significant Accounting Policies) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits Plan
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 1.9	$ 1.8	$ 1.4
Foreign Exchange Transactions
Foreign Currency Transaction Gain (Loss), before Tax	$ (0.6)	(0.5)	(0.3)
Warranty
Product Warranty Period	P12M
Advertising Expense
Advertising Expense	$ 1.3	$ 1.2	$ 1.4

COMPONENTS OF THE COMPANY'S C_3

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Accounts Receivable) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures Abstract
Accounts receivable trade	$ 87,503	$ 66,703
Allowance for ship and debit	(41,599)	(26,435)
Allowance for stock rotation and rebate	(4,066)	(3,931)
Allowance for credit losses	(445)	(427)	$ (763)
Total	$ 41,393	$ 35,910

COMPONENTS OF THE COMPANY'S C_4

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Allowance for Estimated Credit Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Allowance for estimated credit losses
Beginning Balance	$ (427)	$ (763)
Provision for credit loss expense	(1,023)	(621)
Receivables written off	74	198
Recoveries collected	931	759
Ending Balance	$ (445)	$ (427)

COMPONENTS OF THE COMPANY'S C_5

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Inventories) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Inventory, Net [Abstract]
Raw materials	$ 24,131	$ 32,131
Work-in-process	31,788	39,469
Finished goods	43,347	31,278
Total	$ 99,266	$ 102,878

COMPONENTS OF THE COMPANY'S C_6

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Property and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 418,867	$ 380,172
Less: Accumulated depreciation	(239,043)	(213,984)
Property, Plant and Equipment, Net	179,824	166,188
Depreciation	31,454	23,743	$ 19,190
Property and Equipment [Member] | Geographic Concentration Risk [Member] | United States of America
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 174,600	$ 167,000	$ 160,700
Property and Equipment [Member] | Geographic Concentration Risk [Member] | THAILAND
Property, Plant and Equipment [Line Items]
Concentration risk percentage	14.00%	14.00%	14.00%
Property and Equipment [Member] | Geographic Concentration Risk [Member] | Malaysia
Property, Plant and Equipment [Line Items]
Concentration risk percentage	15.00%	14.00%
Land
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 22,187	$ 22,189
Construction-in-progress
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	22,661	34,886
Building and improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	81,027	64,808
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	235,066	202,698
Computer software and hardware and office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 57,926	$ 55,591
Minimum [Member] | Building and improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	4 years
Minimum [Member] | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	2 years
Minimum [Member] | Computer software and hardware and office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	4 years
Maximum [Member] | Building and improvements
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	40 years
Maximum [Member] | Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	8 years
Maximum [Member] | Computer software and hardware and office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and Equipment, Useful Life	7 years

COMPONENTS OF THE COMPANY'S C_7

COMPONENTS OF THE COMPANY'S CONSOLIDATED BALANCE SHEETS (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (2,163)	$ (3,130)	$ (1,689)
Other comprehensive income (loss) before reclassifications	(1,741)	760	(1,508)
Amounts reclassified from accumulated other comprehensive loss	167	207	67
Other comprehensive income (loss)	(1,574)	967	(1,441)
Ending balance	(3,737)	(2,163)	(3,130)
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	890	583	(266)
Other comprehensive income (loss) before reclassifications	(2,055)	307	849
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive income (loss)	(2,055)	307	849
Ending balance	(1,165)	890	583
Defined Benefit Pension Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,641)	(2,484)	(712)
Other comprehensive income (loss) before reclassifications	800	636	(1,839)
Amounts reclassified from accumulated other comprehensive loss	167	207	67
Other comprehensive income (loss)	967	843	(1,772)
Ending balance	(674)	(1,641)	(2,484)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(1,412)	(1,229)	(711)
Other comprehensive income (loss) before reclassifications	(486)	(183)	(518)
Amounts reclassified from accumulated other comprehensive loss	0	0	0
Other comprehensive income (loss)	(486)	(183)	(518)
Ending balance	$ (1,898)	$ (1,412)	$ (1,229)

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	$ 484,570	$ 402,147
Transfer from level 1 to 2	0	0
Transfer from level 2 to 1	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	29,793	1,634
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Investments at Fair Value	454,777	400,513
Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	282,540	146,658
Corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	0	0
Corporate securities | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	282,540	146,658
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	172,237	253,855
Commercial paper | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	0	0
Commercial paper | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	172,237	253,855
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	29,793	1,634
Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	29,793	1,634
Money market funds | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at Fair Value	$ 0	$ 0

MARKETABLE SECURITIES (Details)

MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 373,400	$ 189,428
Gross Unrealized Gains	21	890
Gross Unrealized Losses	(1,186)	0
Estimated Fair Market Value	$ 372,235	$ 190,318
Weighted Average Interest Rate on Investments	0.45%	0.89%
Interest receivable	$ 1,500	$ 800
Marketable securities, unrealized loss	0	0
Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	97,250	63,506
Gross Unrealized Gains	0	44
Gross Unrealized Losses	(3)	0
Estimated Fair Market Value	97,247	63,550
Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,054	125,922
Gross Unrealized Gains	0	846
Gross Unrealized Losses	(42)	0
Estimated Fair Market Value	25,012	126,768
Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,096
Gross Unrealized Gains	21
Gross Unrealized Losses	(1,141)
Estimated Fair Market Value	249,976
Commercial paper | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	89,965	43,660
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	89,965	43,660
Corporate securities | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,285	19,846
Gross Unrealized Gains	0	44
Gross Unrealized Losses	(3)	0
Estimated Fair Market Value	7,282	19,890
Corporate securities | Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,054	125,922
Gross Unrealized Gains	0	846
Gross Unrealized Losses	(42)	0
Estimated Fair Market Value	25,012	$ 126,768
Corporate securities | Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,096
Gross Unrealized Gains	21
Gross Unrealized Losses	(1,141)
Estimated Fair Market Value	$ 249,976

MARKETABLE SECURITIES (Marketab

MARKETABLE SECURITIES (Marketable Securities Unrealized Loss Position) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months Estimated Fair Market Value, Total marketable securities	$ 274,380,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,186,000)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
12 Months or Longer Gross Unrealized Losses, Total marketable securities	0
Total Estimated Fair Market Value, Total marketable securities	274,380,000
Total Gross Unrealized Losses, Total marketable securities	(1,186,000)
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	$ 0
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Less Than 12 Months Estimated Fair Market Value, Total marketable securities	274,380,000
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,186,000)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
12 Months or Longer Gross Unrealized Losses, Total marketable securities	0
Total Estimated Fair Market Value, Total marketable securities	274,380,000
Total Gross Unrealized Losses, Total marketable securities	$ (1,186,000)

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Abstract]
Goodwill	$ 91,849	$ 91,849

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Intangible Assets and Goodwill [Line Items]
Amortization of intangibles	$ 3,494	$ 4,359	$ 5,213
Intangible Assets, Net[Abstract]
Intangible Assets, Gross	57,847	57,847
Accumulated amortization	(48,835)	(45,341)
Total	7,751
Total Intangible Assets, Net	$ 9,012	12,506
Minimum [Member]
Intangible Assets and Goodwill [Line Items]
Useful life (in years)	2 years
Maximum [Member]
Intangible Assets and Goodwill [Line Items]
Useful life (in years)	12 years
Developed technology
Intangible Assets, Net[Abstract]
Finite-Lived Intangible Assets, Gross	$ 37,960	37,960
Accumulated amortization	(31,603)	(29,126)
Total	6,357	8,834
Customer relationships
Intangible Assets, Net[Abstract]
Finite-Lived Intangible Assets, Gross	16,700	16,700
Accumulated amortization	(16,458)	(15,687)
Total	242	1,013
Technology licenses
Intangible Assets, Net[Abstract]
Finite-Lived Intangible Assets, Gross	1,926	1,926
Accumulated amortization	(774)	(528)
Total	1,152	1,398
Internet Domain Names [Member]
Intangible Assets, Net[Abstract]
Indefinite-Lived Intangible Assets	1,261	1,261
Accumulated amortization	$ 0	$ 0

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS (Intangible Assets Amortization Expense) (Details) $ in Thousands	Dec. 31, 2021USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2022	$ 2,415
2023	2,173
2024	1,279
2025	832
2026	687
Thereafter	365
Total	$ 7,751

STOCK PLANS AND SHARE BASED C_4

STOCK PLANS AND SHARE BASED COMPENSATION (Details) $ in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2021USD ($)periodplanshares	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock-based compensation plans | plan	3
Number of shares available for future issuance	5.5
Stock-based compensation expense | $	$ 37,609	$ 30,912	$ 23,347
2016 Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	2.6
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	4.4
Incentive Stock Options [Member] | 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of stock options as percentage of fair market value on date of grant, minimum	100.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	4 years
Stock-based compensation expense | $	$ 19,900	18,700	17,500
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage of employee's compensation eligible for payroll deductions	15.00%
Purchase price of the purchase plan as percentage of the lower of the fair market value on the first day of each offering period or on the purchase date	85.00%
Number of purchase periods in each offering period | period	1
Duration of each purchase period in each offering period	6 months
Shares reserved for issuance	7.5
Number of shares purchased	6.7
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0.8
Stock-based compensation expense | $	$ 2,000	$ 2,000	$ 1,700
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	4 years
Stock Options | 2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	48 months
Stock Options | 2007 Equity Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards expiration period	10 years

STOCK PLANS AND SHARE BASED C_5

STOCK PLANS AND SHARE BASED COMPENSATION (Stock-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 37,609	$ 30,912	$ 23,347
Unrecognized compensation costs	43,355
Cost of revenues
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	2,359	1,963	1,237
Research and development
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	12,127	10,378	8,423
Sales and marketing
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	7,630	6,290	5,015
General and administrative
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 15,493	12,281	8,672
Stock Options
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Awards vesting period	4 years
Performance Based Awards, Long-term and Short-term [Member]
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 15,700	10,200	4,100
Long-Term Performance-Based Awards (PRSUs)
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Performance based period	3 years
Unrecognized compensation costs	$ 7,474
Unrecognized compensation costs, period of recognition (in years)	1 year 2 months 8 days
Number of performance-based awards shares released as a percentage of target number, minimum	0.00%
Number of performance-based awards shares released as a percentage of target number, maximum	200.00%
Restricted Stock Units (RSUs)
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Awards vesting period	4 years
Stock-based compensation expense	$ 19,900	18,700	17,500
Unrecognized compensation costs	$ 35,707
Unrecognized compensation costs, period of recognition (in years)	2 years 3 months 3 days
Employee Stock Purchase Plan
Stock-based compensation expense for stock options, stock awards and employee stock purchases included in operations:
Stock-based compensation expense	$ 2,000	$ 2,000	$ 1,700
Unrecognized compensation costs	$ 174
Unrecognized compensation costs, period of recognition (in years)	29 days

STOCK PLANS AND SHARE BASED C_6

STOCK PLANS AND SHARE BASED COMPENSATION (Fair Value Assumptions) (Details) - Employee Stock Purchase Plan - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rates	0.07%	0.90%	2.28%
Expected volatility rates	41.00%	47.00%	37.00%
Expected dividend yield	0.57%	0.78%	0.91%
Expected term of purchase rights (in years)	6 months	6 months	6 months
Weighted-average estimated fair value of purchase rights	$ 23.92	$ 15.73	$ 19.39

STOCK PLANS AND SHARE BASED C_7

STOCK PLANS AND SHARE BASED COMPENSATION (Option Activity) (Details) - Stock Options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Option activity under the Plans
Outstanding, shares, beginning of period	92	335	670
Outstanding, weighted-average exercise price, beginning of period (per share)	$ 20.63	$ 19.44	$ 16.21
Granted	0	0	0
Granted	$ 0	$ 0	$ 0
Exercised	(80)	(243)	(335)
Exercised	$ 20.50	$ 18.99	$ 12.98
Forfeited or expired	0	0	0
Forfeited or expired	$ 0	$ 0	$ 0
Outstanding, shares, end of period	12	92	335
Outstanding, weighted-average exercise price, end of period (per share)	$ 21.44	$ 20.63	$ 19.44
Outstanding, weighted-average remaining contractual term (in years)	4 months 6 days
Outstanding, aggregate intrinsic value	$ 857
Vested and Exercisable, shares	12
Exercisable, weighted-average remaining contractual term (in years)	4 months 6 days
Exercisable, aggregate intrinsic value	$ 857
Total intrinsic value of options exercised	$ 4,900	$ 9,100	$ 8,300

STOCK PLANS AND SHARE BASED C_8

STOCK PLANS AND SHARE BASED COMPENSATION (Options by Exercise Price Range) (Details) - Exercise Price Range Two [Member] shares in Thousands	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options Outstanding, Exercise Price Range, Lower Range Limit	$ 21.44
Options Outstanding, Exercise Price Range, Upper Range Limit	$ 21.44
Options Outstanding, Number Outstanding | shares	12
Options Outstanding, Weighted Average Remaining Contractual Term (in years)	4 months 6 days
Options Outstanding, Weighted Average Exercise Price (per share)	$ 21.44
Options Vested and Exercisable, Number Vested | shares	12
Options Vested and Exercisable, Weighted Average Exercise Price (per share)	$ 21.44

STOCK PLANS AND SHARE BASED C_9

STOCK PLANS AND SHARE BASED COMPENSATION (Performance-based Awards and Restricted Stock Units) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Performance Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance-based awards shares released as a percentage of target number, minimum	0.00%
Number of performance-based awards shares released as a percentage of target number, maximum	200.00%
Shares
Outstanding, shares at beginning of the period	150,000	121,000	52,000
Granted, shares	105,000	150,000	185,000
Vested, shares	(150,000)	(121,000)	(52,000)
Forfeited or canceled, shares	(1,000)	0	(64,000)
Outstanding, shares at ending of the period	104,000	150,000	121,000
Outstanding, weighted-average grant date fair value per share, beginning of period	$ 46.27	$ 35.06	$ 31.44
Granted, weighted-average grant date fair value per share	84.48	46.31	35.06
Vested, weighted-average grant date fair value per share	46.27	35.06	31.44
Forfeited or expired, weighted-average grant date fair value per share	85.01	0	35.06
Outstanding, weighted-average grant date fair value per share, end of period	$ 84.47	$ 46.27	$ 35.06
Outstanding, weighted-average remaining contractual term (in years)	0 years
Outstanding, aggregate intrinsic value	$ 9,701
Outstanding and expected to vest, shares	104,000
Outstanding and expected to vest, weighted-average remaining contractual term (in years)	0 years
Outstanding and expected to vest, aggregate intrinsic value	$ 9,701
Grant date fair value of awards released	$ 6,900	$ 4,200	$ 1,600
Long-Term Performance-Based Awards (PRSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance-based awards shares released as a percentage of target number, minimum	0.00%
Number of performance-based awards shares released as a percentage of target number, maximum	200.00%
Performance based period	3 years
Shares
Outstanding, shares at beginning of the period	301,000	287,000	426,000
Granted, shares	103,000	152,000	144,000
Vested, shares	(6,000)	0	(140,000)
Forfeited or canceled, shares	(15,000)	(138,000)	(143,000)
Outstanding, shares at ending of the period	383,000	301,000	287,000
Outstanding, weighted-average grant date fair value per share, beginning of period	$ 41.90	$ 32.03	$ 27.74
Granted, weighted-average grant date fair value per share	82.92	49.67	34.09
Vested, weighted-average grant date fair value per share	29.94	0	21.63
Forfeited or expired, weighted-average grant date fair value per share	40.05	29.95	31.50
Outstanding, weighted-average grant date fair value per share, end of period	$ 53.14	$ 41.90	$ 32.03
Outstanding, weighted-average remaining contractual term (in years)	11 months 1 day
Outstanding, aggregate intrinsic value	$ 35,537
Outstanding and expected to vest, shares	383,000
Outstanding and expected to vest, weighted-average remaining contractual term (in years)	11 months 1 day
Outstanding and expected to vest, aggregate intrinsic value	$ 35,537
Grant date fair value of awards released	$ 200		$ 3,000
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period	4 years
Shares
Outstanding, shares at beginning of the period	1,518,000	1,719,000	1,790,000
Granted, shares	271,000	439,000	582,000
Vested, shares	(546,000)	(599,000)	(603,000)
Forfeited or canceled, shares	(99,000)	(41,000)	(50,000)
Outstanding, shares at ending of the period	1,144,000	1,518,000	1,719,000
Outstanding, weighted-average grant date fair value per share, beginning of period	$ 35.51	$ 31.33	$ 29.10
Granted, weighted-average grant date fair value per share	83.79	44.82	34.90
Vested, weighted-average grant date fair value per share	35.03	30.25	28.10
Forfeited or expired, weighted-average grant date fair value per share	39.85	36.77	31.72
Outstanding, weighted-average grant date fair value per share, end of period	$ 46.81	$ 35.51	$ 31.33
Outstanding, weighted-average remaining contractual term (in years)	1 year 3 months
Outstanding, aggregate intrinsic value	$ 106,306
Outstanding and expected to vest, shares	1,081,000
Outstanding and expected to vest, weighted-average remaining contractual term (in years)	1 year 2 months 12 days
Outstanding and expected to vest, aggregate intrinsic value	$ 100,433
Grant date fair value of awards released	$ 19,100	$ 18,100	$ 16,900

SIGNIFICANT CUSTOMERS AND GEO_3

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES (Customer and Credit Risk Concentration) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)customer	Dec. 31, 2020USD ($)customer	Dec. 31, 2019USD ($)customer
Concentration Risk [Line Items]
NET REVENUES | $	$ 703,277	$ 488,318	$ 420,669
Distributors [Member]
Concentration Risk [Line Items]
NET REVENUES | $	$ 525,700	$ 367,700	$ 304,600
Credit Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk [Line Items]
Number of major customers | customer	10	10
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Powertech Distribution Ltd.
Concentration Risk [Line Items]
Concentration risk percentage		10.00%
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Avnet
Concentration Risk [Line Items]
Concentration risk percentage	45.00%	50.00%
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Ten Customers
Concentration Risk [Line Items]
Concentration risk percentage	86.00%	90.00%
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member]
Concentration Risk [Line Items]
Number of major customers | customer	10	10	10
Concentration risk, percentage of total net revenues	78.00%	62.00%	54.00%
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Avnet
Concentration Risk [Line Items]
Concentration risk, percentage of total net revenues	30.00%	19.00%	11.00%
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Honestar Technologies Co., Ltd.
Concentration Risk [Line Items]
Concentration risk, percentage of total net revenues	16.00%	11.00%

SIGNIFICANT CUSTOMERS AND GEO_4

SIGNIFICANT CUSTOMERS AND GEOGRAPHIC NET REVENUES (Geographic Net Revenues) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Revenues by Geography [Line Items]
NET REVENUES	$ 703,277	$ 488,318	$ 420,669
United States of America
Schedule of Revenues by Geography [Line Items]
NET REVENUES	17,238	11,065	10,662
Hong Kong/China
Schedule of Revenues by Geography [Line Items]
NET REVENUES	446,980	306,938	237,341
Taiwan
Schedule of Revenues by Geography [Line Items]
NET REVENUES	25,991	21,650	36,297
Korea
Schedule of Revenues by Geography [Line Items]
NET REVENUES	59,501	40,059	30,395
Western Europe (excluding Germany)
Schedule of Revenues by Geography [Line Items]
NET REVENUES	35,835	33,564	36,025
Japan
Schedule of Revenues by Geography [Line Items]
NET REVENUES	25,101	17,453	15,496
Germany
Schedule of Revenues by Geography [Line Items]
NET REVENUES	32,664	23,242	20,197
Other
Schedule of Revenues by Geography [Line Items]
NET REVENUES	$ 59,967	$ 34,347	$ 34,256

COMMON STOCK REPURCHASES AND _3

COMMON STOCK REPURCHASES AND CASH DIVIDENDS (Common Stock Repurchases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2022	Oct. 31, 2021	Apr. 30, 2021	Oct. 31, 2018
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount							$ 80,000
Stock Repurchased and Retired During Period, Value	$ 73,938	$ 2,636	$ 7,302
Common Stock
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 50,000	$ 50,000
Stock Repurchased and Retired During Period, Shares	878,000	63,000	242,000
Stock Repurchased and Retired During Period, Value	$ 73,900	$ 2,600	$ 7,300
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 67,300
Common Stock | Subsequent Event
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 100,000

COMMON STOCK REPURCHASES AND _4

COMMON STOCK REPURCHASES AND CASH DIVIDENDS (Cash Dividends) (Details)	1 Months Ended							3 Months Ended												12 Months Ended
	Jan. 31, 2022dividend$ / shares	Oct. 31, 2021item$ / shares	Jan. 31, 2021item$ / shares	Jul. 31, 2020item$ / shares	Apr. 30, 2020USD ($)$ / shares	Oct. 31, 2019item$ / shares	Jan. 31, 2019item$ / shares	Dec. 31, 2021$ / shares	Sep. 30, 2021$ / shares	Jun. 30, 2021$ / shares	Mar. 31, 2021$ / shares	Dec. 31, 2020$ / shares	Sep. 30, 2020$ / shares	Jun. 30, 2020$ / shares	Mar. 31, 2020$ / shares	Dec. 31, 2019$ / shares	Sep. 30, 2019$ / shares	Jun. 30, 2019$ / shares	Mar. 31, 2019$ / shares	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Dividends Payable [Line Items]
Common Stock, Dividends, Per Share, Declared								$ 0.15	$ 0.13	$ 0.13	$ 0.13	$ 0.110	$ 0.110	$ 0.105	$ 0.095	$ 0.095	$ 0.085	$ 0.085	$ 0.085
Payments of dividends to stockholders | $																				$ 32,599,000	$ 25,081,000	$ 20,506,000
Common Stock, Dividends, Number of Quarterly Distributions Declared		5	4	2	3	5	4
Common Stock, Dividends, Per Share, Declared, Two Fiscal Years Prior, Each Quarter							$ 0.085
Common Stock, Dividends, Per Share, Declared, Two Fiscal Years Prior, Fourth Quarter						$ 0.01
Common Stock, Dividends, Per Share, Declared, Prior Fiscal Year, Each Quarter						$ 0.095
Common Stock, Dividends Per Share Declared, Prior Fiscal Year, Second Quarter					$ 0.105
Common Stock Dividends Per Share Declared Prior Fiscal Year Third Quarter				$ 0.11	0.105
Common Stock, Dividends Per Share Declared, Prior Fiscal Year, Fourth Quarter				$ 0.11	$ 0.105
Common Stock, Dividends, Increase Per Share, Declared, Current Fiscal Year, Each Quarter			$ 0.02
Common Stock, Dividends, Per Share, Declared, Current Fiscal Year, Each Quarter			$ 0.13
Common Stock, Dividends Per Share Declared, Current Fiscal Year, Fourth Quarter		$ 0.15
Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Each Quarter		$ 0.15
Subsequent Event
Dividends Payable [Line Items]
Common Stock, Dividends, Number of Quarterly Distributions Declared | dividend	4
Common Stock, Dividends, Increase Per Share, Declared, Next Fiscal Year, Each Quarter	$ 0.03
Common Stock, Dividends, Per Share, Declared, Next Fiscal Year, Each Quarter	$ 0.18

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Basic earnings per share:
Net income | $		$ 164,413	$ 71,176	$ 193,468
Weighted-average common shares		60,327,000	59,657,000	58,534,000
Basic earnings per share | $ / shares		$ 2.73	$ 1.19	$ 3.31
Diluted earnings per share:
Net income | $		$ 164,413	$ 71,176	$ 193,468
Weighted-average common shares		60,327,000	59,657,000	58,534,000
Effect of dilutive awards:
Employee stock plans		1,140,000	1,188,000	1,098,000
Diluted weighted-average common shares		61,467,000	60,845,000	59,632,000
Diluted earnings per share | $ / shares		$ 2.67	$ 1.17	$ 3.24
Stock split ratio	2
Stock awards excluded in the computation of diluted earnings per share		0	0	0

PROVISION FOR INCOME TAXES (Det

PROVISION FOR INCOME TAXES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
U.S. and foreign components of income before income taxes [Abstract]
U.S. operations	$ 241	$ (6,252)	$ 82,692
Foreign operations	175,894	81,503	139,722
INCOME BEFORE INCOME TAXES	176,135	75,251	222,414
Current provision (benefit):
Federal	23,648	2,788	18,293
State	2	(181)	184
Foreign	1,608	1,677	1,293
Current provision (benefit)	25,258	4,284	19,770
Deferred provision (benefit):
Federal	(11,449)	348	9,683
State	0	0	0
Foreign	(2,087)	(557)	(507)
Deferred provision (benefit)	(13,536)	(209)	9,176
Income Tax Expense (Benefit), Total	$ 11,722	$ 4,075	$ 28,946
Effective income tax rate reconciliation [Abstract]
Federal statutory tax rate	21.00%	21.00%	21.00%
Business tax credits	(3.60%)	(7.40%)	(2.40%)
Stock-based compensation	(0.60%)	(0.10%)	(0.20%)
Foreign income taxed at different rate	(23.80%)	(22.00%)	(12.70%)
GILTI inclusion	13.10%	10.70%	6.20%
Valuation allowance	1.30%	2.60%	0.80%
Other	(0.70%)	0.60%	0.30%
Effective Income Tax Rate Reconciliation, Percent, Total	6.70%	5.40%	13.00%
Components of deferred income tax assets (liabilities) [Abstract]
Other reserves and accruals	$ 17,193	$ 3,707
Tax credit carry-forwards	23,647	20,713
Stock compensation	1,278	1,494
Capital losses	159	158
Net operating loss	2,370	2,303
Other	692	1,023
Valuation allowance	(27,085)	(24,160)
Deferred tax assets, net of valuation allowance	18,254	5,238
Depreciation	(1,750)	(1,974)
Deferred tax liabilities	(1,750)	(1,974)
Net deferred tax assets	16,504	3,264
Reconciliation of the Beginning and Ending Amount of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Balance at beginning of period	21,051	19,049	$ 18,607
Gross Increase for Tax Positions of Current Year	2,068	2,002	1,379
Gross Decrease for Tax Positions of Prior Years	(1,756)	0	(937)
Unrecognized Tax Benefits, Balance at end of period	21,363	21,051	19,049
Unrecognized tax benefits [Abstract]
Unrecognized Tax Benefits, Balance at end of period	21,363	21,051	$ 19,049
Income tax benefit that would be recorded if unrecognized tax benefits are recognized	10,600
Income tax interest and penalties accrued	800	$ 100
State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	45,600
Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	33,900
Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | New Jersey Division of Taxation [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	800
Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	$ 3,900
Earliest Tax Year [Member] | State and Local Jurisdiction [Member] | California Taxing Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2032
Earliest Tax Year [Member] | Research Tax Credit Carryforward [Member] | State and Local Jurisdiction [Member] | New Jersey Division of Taxation [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 1, 2026
Earliest Tax Year [Member] | Research Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 1, 2030

LEASES AND COMMITMENTS (Leases

LEASES AND COMMITMENTS (Leases Expense and Balance Sheet Information of Operating Leases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Expense	$ 3,300	$ 2,700	$ 2,500
Operating Lease, Right-of-Use Asset	$ 11,887	$ 10,295
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Operating Lease, Liability, Current	$ 3,050	$ 2,682
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Accrued Liabilities, Current	Other Accrued Liabilities, Current
Operating Lease, Liability, Noncurrent	$ 8,371	$ 7,345
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Operating Lease, Liability	$ 11,421	$ 10,027

LEASES AND COMMITMENTS Lease Te

LEASES AND COMMITMENTS Lease Terms and Discount Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lease Terms and Discount Rate [Line Items]
Lessee, Operating Lease, Option Extension Term, Maximum	6 years
Lessee, Operating Lease, Option To Terminate, Minimum Term	1 year
Operating Lease, Weighted Average Remaining Lease Term	4 years 2 months 12 days	4 years 2 months 12 days
Lessee, Operating Lease, Discount Rate	3.30%	3.30%
Minimum [Member]
Lease Terms and Discount Rate [Line Items]
Lessee Operating Lease Remaining Lease Term Range	1 year
Maximum [Member]
Lease Terms and Discount Rate [Line Items]
Lessee Operating Lease Remaining Lease Term Range	8 years

LEASES AND COMMITMENTS Suppleme

LEASES AND COMMITMENTS Supplemental Cash Flows Information Regarding Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating cash flows from operating leases	$ 3,538	$ 2,459
Right-of-use assets obtained in exchange for new operating lease obligations	$ 5,225	$ 2,947

LEASES AND COMMITMENTS Maturiti

LEASES AND COMMITMENTS Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2022	$ 3,472
2023	3,672
2024	2,294
2025	1,047
2026	669
Thereafter	1,339
Total future minimum lease payments	12,493
Less imputed interest	1,072
Total	$ 11,421	$ 10,027

LEASES AND COMMITMENTS Commitme

LEASES AND COMMITMENTS Commitments (Details)	Dec. 31, 2021USD ($)
Commitments and Contingencies Disclosure Abstract
Unrecorded Unconditional Purchase Obligation	$ 0

LEGAL PROCEEDINGS AND CONTING_2

LEGAL PROCEEDINGS AND CONTINGENCIES (Details) - Pending Litigation [Member] $ in Millions	Jan. 06, 2020patent	Apr. 01, 2016patent	Feb. 28, 2019USD ($)	Dec. 31, 2021USD ($)
Patent Infringement Claim One
Gain and Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value | $			$ 6.7	$ 1.2
Loss Contingency, Patents Allegedly Infringed, Number		1
Patent Infringement Claim Two
Gain and Loss Contingencies [Line Items]
Gain Contingency, Patents Allegedly Infringed upon, Number	2

RETIREMENT PLANS (Details)

RETIREMENT PLANS (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net Pension Liability	$ 6	$ 6.9
Plan Assets	9.5	9.7
Projected Benefit Obligation	15.5	16.6
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	0.4
Defined Benefit Pension Items
Defined Benefit Plan Disclosure [Line Items]
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	$ 0.7	$ 1.6	$ 2.5

BANK LINE OF CREDIT (Details)

BANK LINE OF CREDIT (Details) - USD ($) $ in Millions	Dec. 31, 2021	Jul. 27, 2016
Line of Credit Facility [Line Items]
Credit Agreement, maximum borrowing capacity		$ 75
Line of credit, amount outstanding	$ 0
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Credit Agreement, maximum borrowing capacity		$ 20

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Ship and Debit Credits [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 26,435	$ 33,475	$ 40,118
Charged to Costs and Expenses	311,443	257,765	230,278
Deductions	(296,279)	(264,805)	(236,921)
Balance at End of Period	$ 41,599	$ 26,435	$ 33,475