Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 28, 2014		Dec. 29, 2013		Dec. 30, 2012
Income Statement [Abstract]
Revenue	$ 27,845	[1]	$ 26,072	[1]	$ 14,944	[1]
Cost of revenue	16,796		17,305		7,878
Gross profit	11,049		8,767		7,066
Operating expenses:
Research and development	12,186		8,375		8,743
Selling, general and administrative	11,663		12,002		10,481
Restructuring costs	0		181		0
Loss from operations	(12,800)		(11,791)		(12,158)
Gain on sale of TowerJazz Semiconductor Ltd. Shares	0		181		0
Interest expense	(85)		(54)		(61)
Interest income and other expense, net	(126)		(157)		(77)
Loss before income taxes	(13,011)		(11,821)		(12,296)
Provision for income taxes	68		455		18
Net loss	$ (13,079)		$ (12,276)		$ (12,314)
Net loss per share:
Basic (in dollars per share)	$ (0.23)		$ (0.27)		$ (0.29)
Diluted (in dollars per share)	$ (0.23)		$ (0.27)		$ (0.29)
Weighted average shares:
Basic (in shares)	55,401		45,762		41,831
Diluted (in shares)	55,401		45,762		41,831

[1] For all periods presented: New products include all products manufactured on 180 nanometer or small semiconductor processes. Mature products include all products produced on semiconductor processes larger than 180 nanometers