Condensed Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 24, 2011	Sep. 25, 2010	Sep. 24, 2011	Sep. 25, 2010
Condensed Consolidated Statements of Income [Abstract]
Net sales	$ 71,813	$ 86,066	$ 242,409	$ 225,765
Cost and expenses:
Cost of sales	48,458	55,989	163,692	148,261
Research and development	8,824	8,799	27,191	26,460
Selling, general and administrative	11,871	12,497	35,395	31,865
Total cost and expenses	69,153	77,285	226,278	206,586
Income from operations	2,660	8,781	16,131	19,179
Interest and other, net	114	127	340	439
Income before income taxes	2,774	8,908	16,471	19,618
Income tax provision (benefit)	(602)	1,297	1,471	4,402
Net income	$ 3,376	$ 7,611	$ 15,000	$ 15,216
Income per share:
Basic	$ 0.14	$ 0.32	$ 0.62	$ 0.64
Diluted	$ 0.14	$ 0.32	$ 0.61	$ 0.63
Weighted average shares used in computing income per share:
Basic	24,158	23,802	24,093	23,669
Diluted	24,478	24,111	24,481	24,022
Cash dividends declared per share	$ 0.06	$ 0.06	$ 0.18	$ 0.18