Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Income Statement [Abstract]
Net revenue	$ 43,334	$ 42,029	$ 101,588	$ 85,227
Cost of goods sold	27,315	28,733	64,175	57,285
Gross margin	16,019	13,296	37,413	27,942
Operating expenses:
Research, development and engineering	5,184	4,446	10,434	8,970
Selling, general and administrative	8,158	6,690	16,999	14,111
Restructuring and other charges	0	111	0	111
Total operating expenses	13,342	11,247	27,433	23,192
Income from operations	2,677	2,049	9,980	4,750
Interest income (expense), net	(33)	(21)	(67)	(147)
Other income (expense), net	15	(142)	(428)	(63)
Income before income taxes	2,659	1,886	9,485	4,540
Provision for (benefit from) income taxes	78	(30)	599	159
Net income	$ 2,581	$ 1,916	$ 8,886	$ 4,381
Net income per share:
Basic (in usd per share)	$ 0.03	$ 0.03	$ 0.12	$ 0.06
Diluted (in usd per share)	$ 0.03	$ 0.03	$ 0.12	$ 0.06
Shares used in computing net income per share:
Basic (in shares)	74,920	73,532	74,611	69,943
Diluted (in shares)	77,019	74,679	76,973	71,405