Parallel-prefix modulo adders: A Review

Abstract

This brief presents study of some of the most state-of-the-art parallel-prefix modulo adders. Various techniques of parallel-prefix modulo addition like, Ladner-Fischer (LF), Kogge-Stone (KS) and ELM are implemented for general carry recurrence. While another variant of LF is tried for Ling signals. These adders are implemented in ASIC 28/32 nm library saed32hvt_ff0p85v25c for modulo $\mathbf{m}=9,\ 11,\ 13,\ 15$ (i.e. $\mathbf{n}=4$ bits based on $\mathbf{n}=\lceil\log_{2} m \rceil$) and $\mathbf{m}=19,\ 29 (\mathbf{n}=5$ bits) for hardware sharing. Performance comparison is carried out in terms of basic area, delay and power metrics. It is observed that ELM, LF and KS mod adders easily outperforms LF using Ling signals adder.