Note 1 - Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 24, 2016

Notes Tables

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

	Three Months Ended						Nine Months Ended
	September 24,			September 26,			September 24,			September 26,
	2016			2015			2016			2015
Cost of sales	$	160		$	100		$	264		$	413
Research and development		288			256			998			841
Selling, general and administrative		1,220			1,281			4,014			3,827
Total share-based compensation		1,668			1,637			5,276			5,081
Income tax benefit		(76	)		(70	)		(189	)		(181	)
Total share-based compensation, net	$	1,592		$	1,567		$	5,087		$	4,900

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

	Three Months Ended				Nine Months Ended
	September 24,		September 26,		September 24,		September 26,
	2016		2015		2016		2015
Weighted average common shares		26,761		26,175		26,596		25,995
Effect of dilutive stock options		606		621		760		684
		27,367		26,796		27,356		26,679

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

	Three Months Ended						Nine Months Ended
	September 24,			September 26,			September 24,			September 26,
	2016			2015			2016			2015
Customers individually accounting for more than 10% of net sales	three			two			two			two
Percentage of net sales		37.4	%		28.8	%		30.5	%		28.5	%