Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 27, 2015	Sep. 28, 2014
Income Statement [Abstract]
Net revenue	$ 38,894	$ 38,430	$ 140,482	$ 123,657
Cost of goods sold	25,347	25,432	89,522	82,717
Gross margin	13,547	12,998	50,960	40,940
Operating expenses:
Research, development and engineering	4,033	4,849	14,467	13,819
Selling, general and administrative	7,812	7,302	24,811	21,413
Restructuring and other charges	0	301	0	412
Total operating expenses	11,845	12,452	39,278	35,644
Income from operations	1,702	546	11,682	5,296
Interest income (expense), net	(35)	(47)	(102)	(194)
Other income (expense), net	575	148	207	85
Income before income taxes	2,242	647	11,787	5,187
Provision for income taxes	219	110	878	269
Net income	$ 2,023	$ 537	$ 10,909	$ 4,918
Net income per share:
Basic (in usd per share)	$ 0.03	$ 0.01	$ 0.15	$ 0.07
Diluted (in usd per share)	$ 0.03	$ 0.01	$ 0.14	$ 0.07
Shares used in computing net income per share:
Basic (in shares)	75,129	73,731	74,785	71,215
Diluted (in shares)	76,546	75,023	76,849	72,637