Low-power asynchronous Viterbi decoder for wireless applications

This paper describes the implementation of an asynchronous 64-state, 1/2-rate Viterbi decoder using an original architecture and design methodology. The decoder is intended for wireless communications applications, where bit rates over 100 Mb/s and minimum power consumption are sought. The choice of an asynchronous design was predicated by the power and speed advantages of such a methodology. Asynchronous designs are inherently data driven and are active only when doing useful work, enabling considerable savings in power and operating at the average speed of all components. The decoder, implemented in a 0.18 μm CMOS technology, occupies an area of 2 mm² and operates above 200 Mb/s while consuming 85 mW: a 55% power reduction when compared to state of the art synchronous design implemented in a 0.25 μm technology.