Actel rolls line of radiation-hardened FPGAs

Actel Corp. made good on its promise to deliver a new breed of radiation-hardened FPGAs that exceed the reliability requirements of today's satellite systems.

The RTAX-S, based on one-time programmable antifuse technology, improves on earlier rad-hard devices in two areas: gate density and immunity to radiation-induced errors, Altera said.

Actel achieved higher density with a more-advanced 0.15m process based on non-volatile cell structures, giving designers an alternative to rad-hard ASICs that are typically based on 0.35m or older design rules. As a result, Actel packed in 2 million system gates (250, 000 equivalent ASIC gates) into its largest device, the RTAX2000S, along with embedded RAM. Actel will also offer a million-gate spin, RTAX1000S.

Because RAM cells are susceptible to radiation when outside the earth's atmosphere, Actel devised error detection and correction based on Hamming codes, often used to correct single bit-errors. Users can choose the error correction strength by tapping surrounding logic gates, the company said. The more gates, the stronger the protection.

Actel also added what it calls triple-module redundancy to every flip-flop to prevent single-event upsets caused by ion strikes. With this approach, each flip-flop has three data paths linked by a "voter gate, " giving a feedback path so the flip-flop will not change state.

The parts can withstand an ionizing dose of 200k-rads and have a single-event upset rate of 10-10 per bit day at a 35, 000km orbit. Both measures go beyond what is typically required for rad-hard ICs. The company expects to deliver parts that have been fully tested and certified by the middle of next year.

Hardening FPGAs against radiation comes with a price. The smallest device costs $14, 000 while the high-density version is $17, 500. Actel said this is still a bargain when put into context. Companies designing satellite systems typically need no more than 50 devices and wind up spending $20, 000 per device to cover the cost of the non-recurring engineering charges alone, said Barry Marsh, vice president of marketing for Actel.

Actel now offers software and prototypes based on commercial antifuse FPGAs. The company also has a bus controller IP core for rad-hard FPGAs and plans to introduce a bus monitor core next year.

- Anthony Cataldo

EE Times