3. Balance Sheet Components

Inventory

Inventory consisted of the following (in thousands):


	December 31,
	2017		2016
Raw materials	$	682	$	853
Work-in-process		4,517		3,152
Finished goods		4,638		1,064
Total inventory	$	9,837	$	5,069

Property and Equipment, Net

Property and equipment, net consisted of the following (in thousands):


	December 31,
	2017		2016
Manufacturing equipment	$	10,465	$	8,983
Computer and network equipment		710		588
Furniture and fixtures		218		188
Software		455		333
Leasehold improvements		1,474		13
Total property and equipment, gross		13,322		10,105
Less: accumulated depreciation		(9,376)		(8,185)
Total property and equipment, net	$	3,946	$	1,920

Depreciation and amortization expense during the years ended December 31, 2017, 2016 and 2015 was $1.2 million, $0.7 million and $1.2 million, respectively.

Intangible Assets, Net

In 2008, the Company spun-out of Freescale Semiconductor, Inc. (Freescale, a wholly-owned subsidiary of NXP Semiconductors N.V.) and acquired certain intellectual property assets and related licenses used in the MRAM business of Freescale. The value assigned to these acquired intangible assets was $910,000. Intangible assets were fully amortized as of December 31, 2016.

Amortization expense was $0, $132,000 and $150,000 for the years ended December 31, 2017, 2016 and 2015, respectively.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):


	December 31,
	2017		2016
Accrued payroll-related expenses	$	1,331	$	1,045
Deferred licensing revenue		—		229
Deferred rent		230		248
Accrued sales commissions payable to sales representatives		75		193
Other		618		96
Total accrued liabilities	$	2,254	$	1,811