Single Event Upset
Ionizing radiation can cause unwanted effects in the latch state or memory cells of semiconductor devices. These unwanted changes are known as soft errors and are a type of single event upset (SEU). Circuit components within programmable logic devices (PLDs)—such as configuration memory cells, user memory, and registers—can be affected.
Two types of radiation have been the primary cause of SEUs in semiconductor devices: alpha particle radiation and atmospheric neutrons, originating from the effects of cosmic rays. Studies conducted over the last 20 years have led to high purity package materials minimizing SEU effects caused by alpha particle radiation. Unavoidable atmospheric neutrons remain the primary cause for SEU effects today.
Experiments testing the effects of cosmic ray radiation on Altera®FPGAs revealed the following:
- SEUs do not induce latch-up in Altera FPGAs
- An SEU causes only single bit errors within the configuration memory
- MTBFI (1) of hundreds of years, even for the largest FPGA device (2)
Notes:
- MTBFI: Mean Time Between Functional Interrupt
- EP2S180 device at sea level
Industry leaders have conducted studies on the effects of cosmic ray radiation on semiconductor devices. This has led to different solutions at a variety of costs including making the SRAM cells more robust, error correction codes (ECCs), triple module redundancy (TMR) and cyclic redundancy code (CRC). Each of these approaches bring with them various pros and cons at the system level.
Altera has been studying the effects of SEUs on it’s devices for many process generations and has built up extensive experience in both the reduction of soft error rate (SER) through SEU-optimized physical layout and process technology and in soft error mitigation techniques. Altera introduced the industry’s first automatic CRC checker and removed the extra logic and complexity requirements common to other CRC solutions.
Dedicated hard circuitry comes built-in to Stratix® II, Stratix, Stratix II GX, Stratix GX, Cyclone™ II, and Cyclone devices to continually and automatically check CRC at no extra cost. Designers can easily set up the CRC checker through Quartus® II software.
Further information regarding the CRC solution for specific devices can be found by following the links below. For more information regarding other mitigation techniques and for further details about SEU testing of Altera devices, please contact your sales representative or distributor.
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