CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2021	Sep. 26, 2020	Sep. 25, 2021	Sep. 26, 2020
Income Statement [Abstract]
Revenues	$ 189,964	$ 177,996	$ 564,676	$ 496,573
Cost of revenues	109,745	101,247	331,468	286,267
Gross profit	80,219	76,749	233,208	210,306
Operating expenses:
Research and development	26,026	22,878	75,526	65,064
Selling, general and administrative	30,940	31,834	91,434	82,282
Total operating expenses	56,966	54,712	166,960	147,346
Operating income	23,253	22,037	66,248	62,960
Interest income	121	249	463	1,310
Interest expense	(151)	(193)	(447)	(682)
Other expense, net	58	299	36	141
Income before income taxes	23,281	22,392	66,300	63,729
Provision (benefit) for income taxes	2,784	(499)	8,273	4,479
Net income	$ 20,497	$ 22,891	$ 58,027	$ 59,250
Net income per share:
Basic (in dollars per share)	$ 0.26	$ 0.30	$ 0.75	$ 0.78
Diluted (in dollars per share)	$ 0.26	$ 0.29	$ 0.73	$ 0.75
Weighted-average number of shares used in per share calculations:
Basic (in shares)	77,869	77,029	77,643	76,436
Diluted (in shares)	79,029	78,809	79,190	78,534