ESAS: Exponent Series based Approximate Square Root Design

Abstract

Approximate computing is an emerging method-ology that offers hardware benefits when compared with the traditional computing design at the cost of accuracy. It is highly suitable for applications which does not require precision but rather try to preserve exactness of the outcome. Many arithmetic designs have evolved over the years using approximate methodologies. Square-root is one of the common yet complex hardware unit which is often employed in image processing and communication system design application. However not much hardware implementation of square-root function is seen. In this paper a novel square-root design is proposed that offers better accuracy, and improved hardware results compared to that of the previous works. The proposed design utilizes first two terms of exponent series expansion and applies two level of approximation to evolve not only hardware efficient square-root designs but also offer improved error characteristics. The approximate Square-root design was implemented in all the three data-formats including integer, fixed, and IEEE half precision floating point. The proposed designs were validated on Sobel Edge Detection algorithm and envelope detector for communication design to provide accelerated performance.