Stock-Based Compensation (Tables)

6 Months Ended

Jun. 28, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense (in thousands):

	Three months ended				Six months ended
	June 28, 2013		June 29, 2012		June 28, 2013		June 29, 2012
Stock-based compensation in:
Cost of revenue	$	622	$	764	$	1,233	$	1,517
Research and development expense		1,121		1,650		2,324		3,305
Selling, general and administrative expense		2,279		2,169		4,364		4,428
Total stock-based compensation in operating expense		3,400		3,819		6,688		7,733
Total stock-based compensation	$	4,022	$	4,583	$	7,921	$	9,250

Valuation Assumptions for Stock Options

The Company estimated the fair value of all employee stock options using a Black-Scholes valuation model with the following weighted average assumptions:

	Three months ended						Six months ended
	June 28, 2013			June 29, 2012			June 28, 2013			June 29, 2012
Expected term (years)		4.70			4.70			4.70			4.70
Volatility		49	%		54	%		51	%		57	%
Risk-free interest rate		1.1	%		0.9	%		0.8	%		1.0	%
Expected dividends		0.0	%		0.0	%		0.0	%		0.0	%

Employee Stock Purchase Plan

The call option and put option were valued using the Black-Scholes option pricing model with the following assumptions:

	Three months ended						Six months ended
	June 28, 2013			June 29, 2012			June 28, 2013			June 29, 2012
Expected term (years)		0.49			0.50			0.49			0.50
Volatility		30	%		54	%		30	%		54	%
Risk-free interest rate		0.2	%		0.2	%		0.2	%		0.2	%
Expected dividends		0.0	%		0.0	%		0.0	%		0.0	%