A VLSI-efficient signed magnitude comparator for { 2n-1, 2n, 2n +2n+1-1} RNS

Abstract

Comparison of residue representations in signed Residue Number System (RNS) involves sign detection and magnitude comparison. Both are difficult operations in RNS. This paper proposes a new signed magnitude comparator for the three-moduli set RNS {2n-1, 2n, 2n+1-1}. Two subrange identifiers are computed to simplify sign detection and accelerate the magnitude comparison without requiring full reverse conversion, large modulo adders or lookup tables. Synthesis results in 65 nm CMOS standard cell implementation show that it even outperforms the most efficient unsigned magnitude comparator for equally balanced special three-moduli set by significant margin in terms of area, delay and power consumption.