Design methodology for voltage-overscaled ultra-low-power systems

Abstract—This paper proposes a design methodology for volt-age overscaling (VOS) of ultra-low-power systems. This paper first proposes a probabilistic model of the timing error rate for basic arithmetic units and validates it using both simulations and silicon measurements of multipliers in 65-nm CMOS. The model is then applied to a modified K-best decoder that employs error tolerance to reveal the potential of the framework. With simple modifications and timing error detection-only circuitry, the conventional K-best decoder improves its error tolerance in child node expansion modules by up to 30 % with less than 0.4-dB SNR degradation. With this error tolerance, the supply voltage can be overscaled by 12.1%, leading to 22.5 % energy savings. Index Terms—Error-tolerant system, K-best decoder, low-power circuit design, voltage overscaling