Condensed Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net loss	$ (16,708)	$ (18,183)	$ (10,183)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	826	1,340	1,517
Loss on disposal of property and equipment	80
Stock-based compensation	1,141	416	799
Change in fair value of redeemable convertible preferred stock warrant liability	(372)	(15)	(6)
Change in fair value of derivative liability	(798)
Non-cash interest expense	1,183	232	98
Compensation expense related to vesting of common stock to GLOBALFOUNDRIES	965	1,761	107
Changes in operating assets and liabilities:
Accounts receivable	(1,261)	339	(579)
Amounts due from related parties	78	102	(455)
Prepaid expenses and other current assets	(860)	(77)	52
Inventory	(893)	(431)	(297)
Other assets	(21)	(10)	63
Accounts payable	340	233	514
Accrued liabilities	56	428	73
Amounts due to related parties	(2,453)	3,328	(142)
Deferred income on shipments to distributors	387	(362)	501
Deferred revenue	(229)	229
Net cash used in operating activities	(18,539)	(10,670)	(7,938)
Cash flows from investing activities
Purchases of property and equipment	(1,040)	(1,295)	(525)
Net cash used in investing activities	(1,040)	(1,295)	(525)
Cash flows from financing activities
Proceeds from convertible promissory notes-related party	8,500
Proceeds from debt	1,500	8,000	4,000
Payments on debt	(1,325)	(3,000)	(281)
Payments of debt issuance costs	(40)	(130)	(76)
Payments on capital lease obligation	(198)	(226)
Proceeds from issuance of convertible preferred stock			10,027
Proceeds from exercise of stock options	48	4	41
Proceeds from issuance of common stock			1
Proceeds from issuance of common stock in connection with initial public offering, net of offering costs	33,864
Net proceeds from issuance of common stock in private placement, net of issuance costs	4,650
Net cash provided by financing activities	46,999	4,648	13,712
Net increase (decrease) in cash and cash equivalents	27,420	(7,317)	5,249
Cash and cash equivalents at beginning of period	2,307	9,624	4,375
Cash and cash equivalents at end of period	29,727	2,307	9,624
Supplementary cash flow information:
Interest Paid	806	421	165
Interest paid to related party	359
Non-cash investing and financing activities:
Purchase of property and equipment under capital lease obligations		431
Conversion of convertible promissory notes into common stock	8,634		2,016
Issuance of warrants with debt		$ 307	$ 106
Conversion of redeemable preferred stock into common stock	64,642
Reclassification to additional paid-in capital	$ 65