Note 1 - Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 24, 2017

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Three Months Ended						Six Months Ended
	June 24,			June 25,			June 24,			June 25,
	2017			2016			2017			2016
Cost of sales	$	121		$	115		$	204		$	208
Research and development		262			334			578			628
Selling, general and administrative		1,376			1,347			2,694			2,697
Total share-based compensation		1,759			1,796			3,476			3,533
Income tax benefit		(249	)		(73	)		(322	)		(113	)
Total share-based compensation, net	$	1,510		$	1,723		$	3,154		$	3,420

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended				Six Months Ended
	June 24,		June 25,		June 24,		June 25,
	2017		2016		2017		2016
Weighted average common shares		27,708		26,711		27,343		26,514
Effect of dilutive securities		1,017		674		1,145		876
		28,725		27,385		28,488		27,390

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months Ended				Six Months Ended
	June 24,		June 25,		June 24,		June 25,
	2017		2016		2017		2016
Customers individually accounting for more than 10% of net sales		one		one		one		two
Percentage of net sales		20.7%		21.7%		20.4%		32.0%