BALANCE SHEET COMPONENTS

Accounts receivable

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, included in accounts receivable, totaled

$9.4

million and

$7.4

million as of

March 31, 2020,

and

December 31, 2019,

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

$2.8

million and

$4.1

million as of

March 31, 2020,

and

December 31, 2019,

respectively.

Property and equipment

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

	March 31,			December 31,
	2020			2019
Computer equipment	$	10,893		$	10,880
Software		4,685			4,690
Furniture, fixtures and equipment		2,419			2,395
Leasehold improvements		6,087			6,095
Laboratory and other equipment		4,974			4,933
Test equipment		23,604			22,980
Construction-in-progress		19,377			18,245
		72,039			70,218
Less: accumulated depreciation and amortization		(31,030	)		(29,420	)
Total	$	41,009		$	40,798

Test equipment includes DFI™ assets at customer sites that are contributing to DFI™ revenues. The construction-in-progress balance related to construction of DFI™ assets totaled

$17.7

million and

$16.6

million as of

March 31, 2020

and

December 31, 2019,

respectively. Depreciation and amortization expense for the

three

months ended

March 31, 2020

and

2019

was

$1.7

million and

$1.3

million, respectively.

Goodwill and Intangible Assets

As of

March 31, 2020,

and

December 31, 2019,

the carrying amount of goodwill was

$2.3

million.

Intangible assets balance was

$5.9

million and

$6.2

million as of

March 31, 2020

and

December 31, 2019,

respectively. Intangible assets as of

March 31, 2020

and

December 31, 2019

consist of the following (in thousands):

		March 31, 2020							December 31, 2019
	Amortization	Gross					Net		Gross					Net
	Period	Carrying		Accumulated			Carrying		Carrying		Accumulated			Carrying
	(Years)	Amount		Amortization			Amount		Amount		Amortization			Amount
Acquired identifiable intangibles:
Customer relationships	1 ‒ 9	$	7,440	$	(5,047	)	$	2,393	$	7,440	$	(4,935	)	$	2,505
Developed technology	4 ‒ 9		17,460		(14,290	)		3,170		17,460		(14,101	)		3,359
Tradename	2 ‒ 7		790		(679	)		111		790		(673	)		117
Patent	7 ‒ 10		1,800		(1,570	)		230		1,800		(1,560	)		240
Total		$	27,490	$	(21,586	)	$	5,904	$	27,490	$	(21,269	)	$	6,221

The weighted average amortization period for acquired identifiable intangible assets was

6.0

years as of

March 31, 2020.

Intangible asset amortization expense was

$0.3

million during each of the

three

months ended

March 31, 2020

and

2019,

which was recorded in other expense (income), net in the Company’s Condensed Consolidated Statements Comprehensive Loss. The Company expects annual amortization of acquired identifiable intangible assets to be as follows (in thousands):

Year Ending December 31,	Amount
2020 (remaining nine months)	$	952
2021		1,093
2022		886
2023		886
2024		747
2025 and thereafter		1,340
Total future amortization expense	$	5,904

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, 2020,

there were

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