Commitments and Contingencies

Facilities and Equipment Under Operating and Capital Lease Agreements

We currently own our corporate headquarters and select surrounding properties, and a UK office building. We lease certain of our other facilities and certain equipment under operating lease agreements, some of which have renewal options. Certain of these arrangements provide for lease payment increases based upon future fair market rates. As of March 31, 2018, our principal facilities are located in Austin, Texas and Edinburgh, Scotland, United Kingdom.

Total rent expense under operating leases was approximately $11.5 million, $8.2 million, and $5.2 million, for fiscal years 2018, 2017, and 2016, respectively. Sublease rental income was $0.3 million, $0.4 million, and $0.3 million, for fiscal years 2018, 2017, and 2016, respectively.

The aggregate minimum future rental commitments under all operating leases, net of sublease income for the following fiscal years are (in thousands):



	Facilities		Subleases		Net Facilities Commitments		Equipment and Other Commitments		Total Commitments
2019	$	13,315	$	241	$	13,074	$	151	$	13,225
2020	13,631		240		13,391		145		13,536
2021	12,959		245		12,714		145		12,859
2022	12,558		251		12,307		143		12,450
2023	11,788		257		11,531		123		11,654
Thereafter	43,817		602		43,215		363		43,578
Total minimum lease payment	$	108,068	$	1,836	$	106,232	$	1,070	$	107,302

Wafer, Assembly, Test and Other Purchase Commitments

We rely primarily on third-party foundries for our wafer manufacturing needs. Generally, our foundry agreements do not have volume purchase commitments and primarily provide for purchase commitments based on purchase orders, with the exception of a few “take or pay” clauses included in vendor contracts that are immaterial at March 31, 2018. Cancellation fees or other charges may apply and are generally dependent upon whether wafers have been started or the stage of the manufacturing process at which the notice of cancellation is given. As of March 31, 2018, we had foundry commitments of $80.2 million.

In addition to our wafer supply arrangements, we contract with third-party assembly vendors to package the wafer die into finished products. Assembly vendors provide fixed-cost-per-unit pricing, as is common in the semiconductor industry. We had non-cancelable assembly purchase orders with numerous vendors totaling $3.2 million at March 31, 2018.

Test vendors provide fixed-cost-per-unit pricing, as is common in the semiconductor industry. Our total non-cancelable commitment for outside test services as of March 31, 2018 was $11.5 million.

Other purchase commitments primarily relate to multi-year tool commitments, and were $59.7 million at March 31, 2018.