Actel Corporation announced the results of a comprehensive third-party investigation verifying that field-programmable gate arrays (FPGAs) based on flash and antifuse technologies are immune to configuration upsets caused by high-energy neutrons naturally generated in the earth's atmosphere. The study also determined that SRAM-based FPGAs are vulnerable to neutron-induced configuration loss not only under high-altitude conditions, as traditionally believed, but also in ground-based applications, including automotive, medical, telecommunications, and data storage and communications.
The tests, which followed the industry-prescribed JESD-89 test methodology, were conducted in February 2004 by iRoC Technologies at the Los Alamos Neutron Sciences Center at Los Alamos National Laboratory in New Mexico. The results of the independent study are documented in the report, Radiation Results of SER [Soft-Error Rate] Test of Actel, Xilinx and Altera FPGA Instances, which is available free of charge beginning April 19, 2004 at
'iRoC ran tests on different technologies of field programmable devices using identical procedures, the same tester and the same neutron source. As a third party test house, we use a consistent, high quality methodology so results can be compared with confidence. We confirmed that SRAM technology is much more susceptible to soft errors than all other technologies tested,' stated Olivier Lauzeral, Director of U.S. Operations at iRoC Technologies. 'When high-energy neutrons penetrate memory cells, such as those used in SRAM-based programmable logic devices, it is highly probable that functional failure will cause the device to operate in an unpredictable manner. This can be detrimental to systems we rely on every day, such as the telephone network, automotive airbags, medical equipment and even military and aerospace applications.'
Barry Marsh, vice president of product marketing at Actel, stated, 'This report represents the first time devices from Actel, Altera and Xilinx have been simultaneously tested for neutron reliability in a controlled environment. As an independent, repeatable study, we believe the iRoC results clearly demonstrate that immunity to neutron-induced errors must be on a designer's short list of FPGA selection criteria. Actel's antifuse- and flash-based FPGA technologies are inherently immune to neutron-induced functionality changes. Even as process geometries shrink, our underlying architectural benefits will continue to protect the integrity of high-reliability and mission critical designs.'
Test Methodology and Results
In response to industry-wide concern surrounding neutron-induced upsets, iRoC conducted a series of tests to determine the failure rate of five different FPGA architectures, including Virtex-II and Spartan-3 SRAM-based FPGAs from Xilinx; an SRAM-based Cyclone FPGA from Altera; and the antifuse-based Axcelerator FPGA and flash-based ProASIC Plus devices from Actel.
The testing demonstrated that antifuse- and flash-based FPGAs suffered no loss of configuration under neutron bombardment while the tested SRAM-based FPGAs demonstrated a FIT (failures in time) rate ranging from 1,150 at sea level to 3,900 at 5,000 feet to 540,000 at 60,000 feet. One FIT is defined as one failure in 109 hours. While integrated circuits typically have FIT rates lower than 100, high-reliability applications require a FIT rate of 10 to 20.