Segment and geographical information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 28, 2012	Sep. 28, 2012	Jun. 29, 2012	Mar. 30, 2012	Dec. 30, 2011		Sep. 30, 2011	Jul. 01, 2011	Apr. 01, 2011	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Total Net sales	$ 90,418	$ 88,233	$ 100,383	$ 94,135	$ 90,473	[1]	$ 96,014	$ 94,758	$ 88,039	$ 373,169	$ 369,284	$ 432,480
Operating profit (loss) excluding severance, impairment and other associated costs, debt restructuring and related costs, legal reserve and costs related to unsolicited takeover attempt										(441)	(1,064)	16,962
Severance, impairment and other associated costs										5,932	14,719	32,799
Debt restructuring and related costs										1,198	0	0
Legal reserve										5,523	193	0
Cost related to unsolicited takeover attempt										(545)	1,916	0
Operating loss										(12,549)	(17,892)	(15,837)
Interest expense, net										(17,435)	(6,202)	(4,853)
Other income (expense), net										5,213	(561)	(4,356)
Loss from continuing operations before income taxes										(24,771)	(24,655)	(25,046)
Depreciation and amortization										7,824	9,892	17,410
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	90,418	88,233	100,383	94,135	90,473	[1]	96,014	94,758	88,039	373,169	369,284	432,480
Property, Plant and Equipment, Net	29,406				28,605					29,406	28,605
China [Member]
Segment Reporting Information [Line Items]
Total Net sales										190,845	178,750	190,598
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										190,845	178,750	190,598
Property, Plant and Equipment, Net	18,438				20,063					18,438	20,063
United States [Member]
Segment Reporting Information [Line Items]
Total Net sales										46,395	50,139	68,396
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										46,395	50,139	68,396
Property, Plant and Equipment, Net	9,723				5,946					9,723	5,946
Asia, Other Than China [Member]
Segment Reporting Information [Line Items]
Total Net sales										56,969	48,353	68,264
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										56,969	48,353	68,264
Europe [Member]
Segment Reporting Information [Line Items]
Total Net sales										67,575	78,179	90,324
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										67,575	78,179	90,324
Property, Plant and Equipment, Net	631				942					631	942
Other Geographical Groups of Countries [Member]
Segment Reporting Information [Line Items]
Total Net sales										11,385	13,863	14,898
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										11,385	13,863	14,898
Property, Plant and Equipment, Net	39				71					39	71
Korea [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	575				1,583					575	1,583
Network [Member]
Segment Reporting Information [Line Items]
Total Net sales										158,089	169,849	219,229
Operating profit (loss) from continuing operations before severance, impairment and other associated costs, debt restructuring and related costs, legal reserve and costs related to unsolicited takeover attempt										3,519	2,685	24,437
Depreciation and amortization										1,814	3,696	4,293
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										158,089	169,849	219,229
Power [Member]
Segment Reporting Information [Line Items]
Total Net sales										120,145	135,151	127,021
Operating profit (loss) from continuing operations before severance, impairment and other associated costs, debt restructuring and related costs, legal reserve and costs related to unsolicited takeover attempt										5,941	9,275	6,466
Depreciation and amortization										2,119	2,577	2,876
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										120,145	135,151	127,021
Wireless [Member]
Segment Reporting Information [Line Items]
Total Net sales										94,935	64,284	86,230
Operating profit (loss) from continuing operations before severance, impairment and other associated costs, debt restructuring and related costs, legal reserve and costs related to unsolicited takeover attempt										(9,901)	(13,024)	(13,941)
Depreciation and amortization										3,891	3,619	10,241
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales										$ 94,935	$ 64,284	$ 86,230

[1] During the fourth quarter of 2011, we recorded an income tax valuation allowance of $32.5 million. Refer to Note 8, Income taxes, for additional information.