EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2022

EMPLOYEE BENEFIT PLANS

Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The Company estimated the fair value of purchase rights granted under the Employee Purchase Plans during the period using the Black-Scholes-Merton option-pricing model with the following weighted average assumptions, resulting in the following weighted average fair values:

	2021 Purchase Plan						2010 Purchase Plan
	Year Ended December 31,			Year Ended December 31,			Year Ended December 31,
	2022			2021			2020
Expected life (in years)		1.25			1.25			1.25
Volatility		48.73	%		48.00	%		34.25	%
Risk-free interest rate		2.75	%		0.11	%		1.43	%
Expected dividend		—			—			—
Weighted average fair value of purchase rights granted during the period	$	10.00		$	6.71		$	4.83

Schedule of Share-based Payment Awards, Stock Options, Valuation Assumptions

The Company has elected to use the Black-Scholes-Merton option-pricing model, which incorporates various assumptions including volatility, expected life, interest rate and expected dividend. The expected volatility is based on the historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected life of the Company’s stock options. The expected life of an award is based on historical experience and on the

terms and conditions of the stock awards granted to employees. The interest rate assumption is based upon observed Treasury yield curve rates appropriate for the expected life of the Company’s stock options.

	Year Ended December 31,
	2022			2021			2020
Expected life (in years)		—			—			4.45
Volatility		—	%		—	%		40.90	%
Risk-free interest rate		—	%		—	%		0.60	%
Expected dividend		—			—			—
Weighted average fair value per share of options granted during the period	$	—		$	—		$	5.75

No stock options were granted during the years ended December 31, 2022 and 2021.

Schedule of Share-based Payment Arrangement, Expensed and Capitalized Amounts

Stock-based compensation expenses related to the Company’s stock plans and employee stock purchase plans were allocated as follows (in thousands):

	Year Ended December 31,
	2022		2021		2020
Costs of revenues	$	2,974	$	2,563	$	3,454
Research and development		9,391		5,515		4,800
Selling, general and administrative		7,284		4,853		4,209
Stock-based compensation expenses	$	19,649	$	12,931	$	12,463

Schedule of Share-based Payment Arrangement, Options Activity - Additional Information

Additional information with respect to options under the Plans is as follows:

	Outstanding Options
				Weighted
		Weighted		Average
		Average		Remaining	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Options	Price		Term	Value
	(in thousands)	per Share		(Years)	(in thousands)
Outstanding, January 1, 2020	745	$	10.64
Granted (weighted average fair value of $5.75 per share)	24	$	16.72
Exercised	(246)	$	10.46
Canceled	(57)	$	11.65
Expired	(10)	$	10.06
Outstanding, December 31, 2020	456	$	10.95
Granted	—	$	—
Exercised	(216)	$	8.90
Canceled	(10)	$	15.56
Expired	(4)	$	6.90
Outstanding, December 31, 2021	226	$	12.78
Granted	—		—
Exercised	(150)		11.27
Canceled	(6)		13.52
Expired	(2)		8.79
Outstanding, December 31, 2022	68	$	16.11	4.89	$	847
Vested and expected to vest, December 31, 2022	68	$	16.11	4.87	$	842
Exercisable, December 31, 2022	57	$	16.07	4.46	$	706

Schedule of Share-based Payment Arrangement, Restricted Stock Unit Activity

Nonvested shares (restricted stock units) were as follows:

		Weighted
		Average Grant
	Shares	Date Fair Value
	(in thousands)	Per Share
Nonvested, January 1, 2020	1,887	$	12.30
Granted	890	$	21.31
Vested	(867)	$	13.25
Forfeited	(163)	$	13.23
Nonvested, December 31, 2020	1,747	$	16.33
Granted	977	$	19.43
Vested	(689)	$	15.23
Forfeited	(163)	$	17.63
Nonvested, December 31, 2021	1,872	$	18.24
Granted	1,210	$	23.23
Vested	(862)	$	17.57
Forfeited	(96)	$	19.71
Nonvested, December 31, 2022	2,124	$	21.29