Stockholders' Equity (Tables)

Total stock-based compensation expense included in our Consolidated Statements of Operations was as follows:



	Year Ended
(In thousands)	January 3, 2015		December 28, 2013		December 29, 2012
Line item:
Cost of products sold	$	819	$	627	$	525
Research and development	5,176		3,916		3,009
Selling, general and administrative	6,807		4,979		3,976
Total stock-based compensation	$	12,802	$	9,522	$	7,510



	Year Ended
	January 3, 2015	December 28, 2013	December 29, 2012
Employee and Director Stock Options
Expected volatility	45.4% to 50.4%	51.4% to 54.3%	58.1% to 59.5%
Risk-free interest rate	1.5%-1.7%	0.7% to 1.0%	0.6% to 1.0%
Expected term	4.1 to 4.7 years	4.1 to 4.5 years	4.1 to 4.5 years
Dividend yield	—%	—%	—%
Employee Stock Purchase Plan
Weighted average expected volatility	38.7%	48.0%	50.0%
Weighted average risk-free interest rate	0.08%	0.11%	0.12%
Expected term	6 months	6 months	6 months
Dividend yield	—%	—%	—%

The following table summarizes our stock option activity and related information for the year ended January 3, 2015:



(Shares and aggregate intrinsic value in thousands)	Shares		Weighted average exercise price		Weighted average remaining contractual term (years)	Aggregate Intrinsic Value
Balance, December 28, 2013	10,441		$	4.88
Granted	1,932		7.16
Exercised	(2,486	)	4.41
Forfeited or expired	(512	)	5.41
Balance, January 3, 2015	9,375		$	5.45
Vested and expected to vest at January 3, 2015	9,375		$	5.45	4.56	$	14,427
Exercisable, January 3, 2015	5,114		$	5.01	3.66	$	9,827

The following table summarizes our RSU activity for the year ended January 3, 2015:



(Shares in thousands)	Shares		Weighted average grant date fair value
Balance at December 28, 2013	2,190		$	5.49
Granted	1,316		7.50
Vested	(1,302	)	5.61
Forfeited	(183	)	6.18
Balance at January 3, 2015	2,021		$	6.66