BALANCE SHEET COMPONENTS

Accounts receivable include amounts that are unbilled at the end of the period that are expected to be billed and collected within

-month period. Unbilled accounts receivable are primarily determined on an individual contract basis. Unbilled accounts receivable, included in accounts receivable, totaled

$22.7

million and

$20.8

million as of

March

31,

2017

and

December

31,

2016,

respectively. Unbilled accounts receivable that are not expected to be billed and collected during the succeeding

-month period are recorded in other non-current assets and totaled

$11.8

million and

$9.8

million as of

March

31,

2017

and

December

31,

2016,

respectively. Deferred costs balance was

$0.6

million and

$0.5

million as of

March

31,

2017

and

December

31,

2016,

respectively. The balance was included in prepaid expense and other current assets and other non-current assets in the accompanying balance sheets.

Property and equipment, net consists of (in thousands):

	March 31 , 201 7			December 31, 2016
Property and equipment, net:
Computer equipment	$	10,568		$	10,642
Software		2,363			1,679
Furniture, fixtures and equipment		1,811			1,185
Leasehold improvements		1,961			1,132
Test equipment		11,843			11,723
Construction-in-progress		9,575			9,550
		38,121			35,911
Less: accumulated depreciation		(17,323	)		(16,570	)
Total	$	20,798		$	19,341

Depreciation and amortization expense was

$1.1

million and

$0.8

million for the

three

months ended

March

31,

2017

and

2016,

respectively.

As of both

March

31,

2017

and

December

31,

2016,

the carrying amount of goodwill was

$0.2

million. The following is a rollforward of the Company's goodwill balance (in thousands):

	March 31 , 201 7
Balance as of December 31, 2016	$	215
Add: Goodwill from acquisition		—
Adjustment		—
Balance as of March 31, 2017	$	215

Intangible assets balance was

$4.0

million and

$4.2

million as of

March

31,

2017

and

December

31,

2016,

respectively. Intangible assets as of

March

31,

2017

and

December

31,

2016

consist of the following (in thousands):

				March 31, 2017							December 31, 201 6
	Amortization Period (Years)			Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Acquired identifiable intangibles:
Customer relationships	1	-	9	$	5,920	$	(3,895	)	$	2,025	$	5,920	$	(3,825	)	$	2,095
Developed technology	4	-	6		14,100		(12,455	)		1,645		14,100		(12,359	)		1,741
Tradename	2	-	4		610		(595	)		15		610		(583	)		27
Backlog		1			100		(100	)		-		100		(100	)		-
Patent	7	-	10		1,800		(1,450	)		350		1,800		(1,440	)		360
Other acquired intangibles		4			255		(255	)		-		255		(255	)		-
Total				$	22,785	$	(18,750	)	$	4,035	$	22,785	$	(18,562	)	$	4,223

The weighted average amortization period for acquired identifiable intangible assets was

6.18

years as of

March

31,

2017.

For both the

three

months ended

March

31,

2017

and

2016,

intangible asset amortization expense was

$0.2

million. The Company expects annual amortization of acquired identifiable intangible assets to be as follows (in thousands):

Period Ending March 31 ,
2017	$	540
2018		701
2019		701
2020		701
2021		526
2022 and thereafter		866
Total future amortization expense	$	4,035

Intangible assets are amortized over their useful lives unless these lives are determined to be indefinite. Intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group

may

not be recoverable. During the

three

months ended

March

31,

2017,

there were

indicators of impairment related to the Company’s intangible assets.