Condensed Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net loss	$ (14,274)	$ (16,719)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,069	837
Loss on disposal of property and equipment	19
Stock-based compensation	2,064	1,511
Non-cash loss on extinguishment of debt		185
Non-cash interest expense	286	188
Compensation expense related to vesting of common stock to GLOBALFOUNDRIES	709	1,224
Changes in operating assets and liabilities:
Accounts receivable	(1,876)	(527)
Inventory	309	(2,628)
Prepaid expenses and other current assets	154	320
Other assets		(11)
Accounts payable	(140)	(333)
Accrued liabilities	4,840	1,109
Deferred income on shipments to distributors		323
Shipping term reversal	(39)
Net cash used in operating activities	(6,879)	(14,521)
Cash flows from investing activities
Purchases of property and equipment	(1,513)	(2,170)
Net cash used in investing activities	(1,513)	(2,170)
Cash flows from financing activities
Proceeds from the issuance of common stock, net of offering costs	24,524
Proceeds from debt	1,000	12,000
Payments on debt	(1,000)	(8,356)
Payments of debt issuance costs		(49)
Payments on capital lease obligation	(8)	(7)
Proceeds from exercise of stock options and purchase of shares in employee stock purchase plan	2,364	1,218
Net cash provided by financing activities	26,880	4,806
Net increase (decrease) in cash and cash equivalents	18,488	(11,885)
Cash and cash equivalents at beginning of period	12,950	29,727
Cash and cash equivalents at end of period	31,438	17,842
Supplementary cash flow information:
Interest paid	370	396
Non-cash investing and financing activities:
Purchase of property and equipment in accounts payable	183	$ 764
Issuance of warrants with debt	$ 43