Measurements and analysis of SER-tolerant latch in a 90-nm dual-VT CMOS process

We designed a soft error rate (SER) tolerant latch utilizing local redundancy. We implemented a test chip containing both the standard and SER-tolerant latches in a 90-nm dual-V-T CMOS process. Accelerated measurements with a neutron beam at Los Alamos National Laboratory demonstrated 10 x better reliability of the SER-tolerant latch over the standard latch at no speed degradation. The worst case energy and area penalties were 39% and 44%, respectively. Both the energy and area penalties are negligible for standard-latch transistor sizes at least double the minimum width. We analyzed the effects of the recovery time, threshold voltage assignment, and leakage on the SER robustness. The proposed latch can improve reliability of critical sequential logic elements in microprocessors and other circuits.