Low-power logarithmic number system addition/subtraction and their impact on digital filters

This paper discusses techniques for low-power addition/subtraction in the logarithmic number system (LNS) and evaluates their impact on digital filter implementation. Initially, the impact of partitioning the look-up tables (LUT) required for addition/subtraction on complexity, performance, and power dissipation is studied. Subsequently techniques for the low-power implementation of an LNS multiply- accumulate (MAC) unit are investigated. The obtained LNS MACs are used for the design of digital filters. Synthesis of LNS-based digital filters using a 0.18 mum 1.8 V CMOS standard-cell library, reveal that significant power dissipation savings are possible at no performance penalty, when compared to linear two´s-complement equivalent.