An exponential function accelerator with radix-16 algorithm for spiking neural networks

A range reduction method for shift-and-add algorithms for exponential functions is proposed in this paper. An exponential function accelerator with this method and radix-16 shift-and-add algorithm has been implemented in SMIC 55 nm CMOS process. Compared with the existing method, the proposed method reduces the latency (cycles) by 33% and 20% for 16 and 32-bit precision results, respectively; thereby increasing the throughputto50Mexp/sandreducingthepowerconsumptionto4.6pJ/exp.Inaddition,thismethodsavesdieareasincenoarithmeticunitsareadopted.Thisexponentialacceleratorissupposedtobeusedinaneuromorphicchipforspikingneuralnetworkmodeling.