Segment Information Revenue by Product Line (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Apr. 26, 2015	Apr. 27, 2014
Revenue from External Customer [Line Items]
Net sales	$ 130,088	$ 132,859
Signal Integrity [Member]
Revenue from External Customer [Line Items]
Net sales	54,309	51,279
Protection [Member]
Revenue from External Customer [Line Items]
Net sales	37,127	48,671
Wireless, Sensing and Timing [Member]
Revenue from External Customer [Line Items]
Net sales	22,798	18,348
Power and High Reliability [Member]
Revenue from External Customer [Line Items]
Net sales	14,013	13,445
Systems Innovation [Member]
Revenue from External Customer [Line Items]
Net sales	$ 1,841	$ 1,116
Net sales [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	100.00%	100.00%
Net sales [Member] | Signal Integrity [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	41.00%	39.00%
Net sales [Member] | Protection [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	29.00%	36.00%
Net sales [Member] | Wireless, Sensing and Timing [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	18.00%	14.00%
Net sales [Member] | Power and High Reliability [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	11.00%	10.00%
Net sales [Member] | Systems Innovation [Member]
Revenue from External Customer [Line Items]
Concentration risk, percentage	1.00%	1.00%