MOUNTAIN VIEW, Calif., August 7, 2006 — Actel Corporation (Nasdaq: ACTL) today announced that a comprehensive third-party investigation confirms that Actel’s flash-based field-programmable gate arrays (FPGAs) are immune to configuration upsets caused by high-energy neutrons naturally generated in the earth’s atmosphere. The study also determined that advances in semiconductor manufacturing technology have had a detrimental impact on the reliability of SRAM-based FPGAs, making them more vulnerable to neutron-induced configuration loss, a major concern for designers of high-reliability systems such as medical, telecommunications, storage area network (SAN), military and avionics systems. Configuration loss also poses a threat to the quality of high-volume consumer and automotive applications. The study was conducted in December 2005, by iRoC Technologies at the Los Alamos Neutron Sciences Center (LANSCE) at Los Alamos National Laboratory in New Mexico.
“iRoC Technologies’ test service is positioned as a totally independent test house, which leverages its wide experience to provide its customers the most accurate and reliable test methodology,” said Olivier Lauzeral, director of U.S. operations at iRoC Technologies. “For this particular test, we chose to run the experiment at LANSCE to replicate closely the energy spectrum found in naturally occurring background neutron radiation in the earth’s atmosphere and at ground level. Our high-quality testing methodology uses identical procedures for each device, including the same tester and the same neutron source, in a controlled environment so tests are repeatable and results can be compared with confidence.”
Ken O’Neill, director of military and aerospace product marketing at Actel, said, “The iRoC results demonstrate that neutron-induced configuration upsets pose a real threat to product quality and reliability, an important consideration as semiconductors proliferate into more of the high-reliability systems we depend on every day. Because Actel’s flash-based technologies are inherently immune to these functionality changes, designers can count on the ProASIC3 FPGAs and Fusion Programmable System Chips to protect design integrity, even as process geometries shrink.”
Further, according to O’Neill, by eliminating neutron-based firm errors as a source of field failures, Actel allows designers of consumer products to meet stringent price and power goals without compromising product quality.
Test Methodology and Results
iRoC conducted a series of tests, following the industry-prescribed JESD-89 test methodology, to determine the failure rate of different FPGA architectures, including flash-based ProASIC3 devices from Actel and SRAM-based FPGAs from another vendor. Effects measured included disruption to FPGA functionality due to configuration loss; data upsets in user memory, flip-flops and combinatorial logic; and latch-up effects.
When high-energy neutrons penetrate memory cells, such as those used in volatile SRAM-based programmable logic devices, it is highly probable that functional failure will cause the device to operate in an unpredictable manner. This harmful effect can occur not only under high-altitude conditions but also in ground-based applications.
Nonvolatile flash-based FPGAs suffered no loss of configuration under neutron bombardment. On the other hand, the upset rate for the tested SRAM-based FPGAs confirmed a trend of increasing susceptibility as process technology advances. Each SRAM FPGA tested included an operational CRC-based (cyclical redundancy checking) upset detection mechanism intended to alert the host system that an upset may have occurred. However, this mechanism did not prevent or fix a configuration upset, it merely alerted the system that an upset may have occurred. Moreover, the alert was raised a significant period of time after the configuration upset had taken place.
Further, one of the SRAM-based FPGAs exhibited a small number of events where bursts of data errors occurred, accompanied by an increase in current consumption during testing. To clear these events, it was necessary to “power-cycle” the device.
Techniques used to recover SRAM-based FPGAs from neutron-induced configuration loss are cumbersome and expensive. Some require system-level design intervention to monitor device configuration status, reload and restart the FPGA if an upset is detected. This causes a degree of latency that is not acceptable in a real-time system. A costly alternative is a triple-module redundant implementation – using three FPGAs instead of one – with additional upset immune circuitry to control majority voting, configuration monitoring and reload/restart circuits.
Each of the FPGAs tested was found to exhibit data upsets in user memory, flip flops and combinatorial logic. A much less severe problem causing only a single-bit error with each event, these data upsets can be mitigated with standard data-integrity techniques, such as error detection and correction codes (EDAC), parity checking and CRC, that can be easily implemented to protect data.
The complete results of the independent study are documented in the report, “Radiation Results of the SER Test of Actel FPGA in December 2005,” which is available free of charge from Actel Corporation.
About Actel
Actel Corporation is the leader in single-chip FPGA solutions. The Company is traded on the NASDAQ National Market under the symbol ACTL and is headquartered at 2061 Stierlin Court, Mountain View, Calif., 94043-4655. For more information about Actel, visit www.actel.com. Telephone: 888-99-ACTEL (992-2835).