Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013
Income Statement [Abstract]
Revenue	$ 99,320	$ 84,694	$ 195,957	$ 155,852
Costs and expenses:
Cost of products sold	44,345	39,584	86,844	72,587
Research and development	22,302	20,267	43,541	38,381
Selling, general and administrative	18,832	17,072	37,581	33,570
Amortization of intangible assets	737	737	1,474	1,486
Restructuring charges	3	19	14	172
Costs and expenses	86,219	77,679	169,454	146,196
Income from operations	13,101	7,015	26,503	9,656
Other income (expense), net	906	(54)	1,215	(106)
Income before income taxes	14,007	6,961	27,718	9,550
Provision for income taxes	2,236	1,921	3,963	2,620
Net income	$ 11,771	$ 5,040	$ 23,755	$ 6,930
Net income per share:
Basic (in dollars per share)	$ 0.10	$ 0.04	$ 0.20	$ 0.06
Diluted (in dollars per share)	$ 0.10	$ 0.04	$ 0.20	$ 0.06
Shares used in per share calculations:
Basic (in shares)	117,904	115,733	117,170	115,562
Diluted (in shares)	120,944	117,109	120,041	116,935