Engineering and Computer Science Faculty Publications

A Fast, Low-Power Logarithm Approximation with CMOS VLSI Implementation

Document Type

Conference Proceeding

Publication Date


Journal Title

Proceedings of the Midwest Symposium on Circuits and Systems


A new technique and CMOS VLSI implementation for computing approximate logarithms (base 2, and 10) for binary integers is presented. The approximation is performed using only combinational logic and requires no multiplications. Additionally, as implemented a ROM of only N*log2(N) bits is used to convert N bit integers. The maximum error of the approximation is 1.5% when the input value is 3, and decays exponentially to less than 0.5% for input values greater than 25.