Note 6. Balance sheet components

Accounts receivable, net

Accounts receivable, net consists of the following (in thousands):

	March 31, 2014			December 31, 2013
Accounts receivable	$	64,586		$	57,010
Trade notes receivable		6,480			8,054
Allowance for doubtful accounts		(419	)		(531	)
	$	70,647		$	64,533

Inventories

Inventories consist of the following (in thousands):

	March 31, 2014		December 31, 2013
Raw materials	$	27,876	$	26,379
Work in process		22,844		14,341
Finished goods ⁽¹⁾		17,229		24,188
	$	67,949	$	64,908

⁽¹⁾Finished goods inventory at customer vendor managed inventory locations was $4.9 million and $5.4 million as of March 31, 2014 and December 31, 2013, respectively.

Purchased intangible assets

Purchased intangible assets consist of the following (in thousands):

	March 31, 2014							December 31, 2013
	Gross Assets		Accumulated Amortization			Net Assets		Gross Assets		Accumulated Amortization			Net Assets
Technology and patents	$	34,250	$	(26,337	)	$	7,913	$	34,524	$	(25,931	)	$	8,593
Customer relationships		14,920		(9,967	)		4,953		15,004		(9,732	)		5,272
Leasehold interest		1,373		(267	)		1,106		1,406		(266	)		1,140
Noncompete agreements		950		(950	)		—		950		(950	)		—
	$	51,493	$	(37,521	)	$	13,972	$	51,884	$	(36,879	)	$	15,005

Amortization expense relating to technology and patents and the leasehold interest intangible assets is included within cost of goods sold, and customer relationships within operating expenses. The following table presents details of the amortization expense of the Company’s purchased intangible assets as reported in the condensed consolidated statements of operations (in thousands):

	Three Months Ended March 31,
	2014		2013
Cost of goods sold	$	714	$	428
Operating expenses		379		321
Total	$	1,093	$	749

The estimated future amortization expense of purchased intangible assets as of March 31, 2014, is as follows (in thousands):

2014 (remaining 9 months)	$	3,275
2015		4,426
2016		3,682
2017		807
2018		591
Thereafter		1,191
	$	13,972

Accrued and other current liabilities

Accrued and other current liabilities consist of the following (in thousands):

	March 31, 2014		December 31, 2013
Employee-related accrued expenses	$	14,449	$	12,297
Other accrued expenses		11,372		11,346
Penalty payment derivative		425		—
	$	26,246	$	23,643

Warranty Accrual

The table below summarizes the movement in the warranty accrual, which is included in accrued and other current liabilities (in thousands):

	Three Months Ended March 31,
	2014			2013
Beginning balance	$	1,737		$	1,072
Warranty accruals		289			26
Settlements and adjustments		(357	)		86
Ending balance	$	1,669		$	1,184

Other noncurrent liabilities

Other noncurrent liabilities consist of the following (in thousands):

	March 31, 2014		December 31, 2013
Pension and other employee-related	$	6,098	$	6,206
Penalty payment derivative		—		239
Other		1,346		1,542
	$	7,444	$	7,987