Balance Sheet Components (Details) - USD ($) $ in Thousands	Jul. 01, 2018	Dec. 31, 2017
Inventories:
Work-in-process	$ 3,519	$ 2,894
Finished goods	771	665
Inventories	4,290	3,559
Other current assets:
Prepaid expenses	837	836
Other	262	161
Other current assets	1,099	997
Property and equipment:
Property and equipment, gross	14,576	14,855
Accumulated depreciation and amortization	(12,786)	(12,480)
Property and equipment, net	1,790	2,375
Accrued liabilities:
Employee related accruals	1,187	1,143
Other	641	510
Accrued liabilities	1,828	1,653
Equipment
Property and equipment:
Property and equipment, gross	11,040	10,996
Software
Property and equipment:
Property and equipment, gross	2,811	3,139
Furniture and fixtures
Property and equipment:
Property and equipment, gross	42	46
Leasehold improvements
Property and equipment:
Property and equipment, gross	$ 683	$ 674