Employee Benefit Plans and Stock-based Compensation (Tables)

9 Months Ended

Sep. 25, 2020

Share-based Payment Arrangement [Abstract]

Summary of Stock Options Outstanding

The following table summarizes the Company’s stock option activities and related information during the nine months ended September 25, 2020 (in thousands, except per share amounts and terms):

	Stock Options Outstanding
	Number of Shares		Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
Balance at December 31, 2019	1,888		$	5.83
Exercised	(127	)	5.78
Canceled or expired	(208	)	5.82
Balance at September 25, 2020	1,553		5.84		1.44	$	1,004
Vested and exercisable	1,553		$	5.84	1.44	$	1,004

Summary of Restricted Stock Units Outstanding

The following table summarizes the Company’s RSUs activities and related information during the nine months ended September 25, 2020 (in thousands, except per share amounts):

	Restricted Stock Units Outstanding
	Number of Shares		Weighted Average Grant Date Fair Value Per Share
Balance at December 31, 2019	3,601		$	5.18
Granted	2,900		5.84
Vested	(2,496	)	5.39
Forfeited	(389	)	4.57
Balance at September 25, 2020	3,616		$	5.63

Schedule of Defined Benefit Plans Obligations

The table below presents the components of net periodic benefit costs (in thousands):

	Three months ended				Nine months ended
	September 25, 2020		September 27, 2019		September 25, 2020		September 27, 2019
Service cost	$	65	$	57	$	187	$	171
Interest cost	9		20		27		59
Net periodic benefit cost	$	74	$	77	$	214	$	230

Summary of Stock-Based Compensation Expense

Stock-based Compensation

The following table summarizes stock-based compensation for all plans (in thousands):

	Three months ended				Nine months ended
	September 25, 2020		September 27, 2019		September 25, 2020		September 27, 2019
Stock-based compensation in:
Cost of revenue	$	284	$	410	$	1,366	$	830
Research and development expense	1,110		1,120		3,720		2,318
Selling, general and administrative expense	2,536		2,566		8,651		5,571
Total stock-based compensation in operating expense	3,646		3,686		12,371		7,889
Total stock-based compensation	$	3,930	$	4,096	$	13,737	$	8,719

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

	ESPP Purchase Period Ending
	December 31, 2020			July 1, 2020			December 31, 2019			July 1, 2019
Expected term (years)	0.5			0.5			0.5			0.5
Volatility	62		%	50		%	33		%	43		%
Risk-free interest rate	0.2		%	1.6		%	2.1		%	2.5		%
Expected dividends	0.0		%	0.0		%	0.0		%	0.0		%
Estimated weighted average fair value per share at purchase date	$	1.54		$	2.26		$	1.36		$	1.31