Stock-Based Employee Compensation (Tables)

9 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Compensation expense

The following table summarizes stock-based compensation expense by line items appearing in the Company’s Condensed Consolidated Statements of Operations:

	Three Months Ended				Nine Months Ended
(in thousands)	December 31, 2017		January 1, 2017		December 31, 2017		January 1, 2017
Cost of revenue	$	790	$	689	$	2,186	$	2,270
Research and development	6,816		4,342		18,871		11,841
Selling, general and administrative	5,974		4,875		17,291		15,491
Total stock-based compensation expense	$	13,580	$	9,906	$	38,348	$	29,602

Stock option activity

The following is a summary of the Company's stock option activity and related weighted average exercise prices for each category:

	Nine Months Ended December 31, 2017
(shares in thousands)	Shares		Price
Beginning stock options outstanding	1,374		$	13.01
Exercised (1)	(225	)	8.46
Canceled	(15	)	23.86
Ending stock options outstanding	1,134		$	13.78
Ending stock options exercisable	968		$	12.70

(1) Upon exercise, the Company issues new shares of common stock.

Nonvested restricted stock units activity

The following table summarizes the Company's RSU activity and related weighted-average exercise prices for each category for the nine months ended December 31, 2017:

	Nine Months Ended December 31, 2017
(shares in thousands)	Shares		Weighted-average grant date fair value per share
Beginning RSUs outstanding	3,840		$	18.88
Assumed from GigPeak acquisition	328		23.62
Granted	2,349		24.34
Released	(1,409	)	17.34
Forfeited	(356	)	21.63
Ending RSUs outstanding	4,752		$	22.16

Fair value assumptions

The following weighted average assumptions were used to calculate the fair value of the market-based equity award using a Monte Carlo simulation model:

	May 15, 2017			June 15, 2016			June 15, 2015			June 15, 2014
Estimated fair value	$	27.65		$	28.01		$	33.08		$	21.00
Expected volatility	43.36		%	46.90		%	41.22		%	34.6		%
Expected term (in years)	2.88			1.80			1.80			1.80
Risk-free interest rate	1.47		%	0.70		%	0.65		%	0.38		%

Employee stock purchase plan activity

Activity under the Company's ESPP for the nine months ended December 31, 2017 is summarized in the following table:

(in thousands, except per share amounts)
Number of shares issued	293
Average issuance price	$	21.23
Number of shares available as of December 31, 2017	2,971