Static window addition: A new paradigm for the design of variable latency adders

Abstract

Speculative adders have attracted strong interest for achieving sublogarithmic delays by exploiting the tradeoffs between correctness and performance. Speculative adders also find use in the design of error-free variable latency adders, which combine speculation with error correction to achieve high performance for low area overhead over traditional adders. This paper describes static window addition (SWA), a novel function speculation technique for the design of low overhead, high performance variable latency adders. Analytical models for the error rate of SWA-based speculative adders are developed to facilitate both design exploration and convergence. We show that on average, variable latency addition using SWA-based speculative adders is 10% faster than the fastest DesignWare adder with area requirements of -5 to 40% for different adder widths.