Approximate Adder Circuits: A Comparative Analysis and Evaluation

Abstract

AbstractApproximate Computing has emerged as a propitious solution for faster, energy-efficient and less complex designs for circuits. Approximate arithmetic circuits are a type of circuit that achieves power and area efficiency by intentionally introducing imperfections into circuit’s output behavior. In arithmetic circuits adder plays a prominent role. It has become essential to understand the approximation techniques and methods to enhance performance and efficiency. This paper aims to provide a comprehensive review on approximate adders and comparatively assessed in terms of error and performance based on speed, area and power. Arithmetic circuits are implemented and synthesized using HDLs and design compiler and error characterization is done by using MATLAB. In this paper power, speed and area are compared with respect to error distance, normalized mean error distance and mean relative error distance. The comparative result conveys that equal segmentation adder has low accuracy but it is a hardware efficient design. After evaluation analysis conveys that equally accurate adders are error-tolerant adder type II, Speculative carry select adder and the accuracy configurable approximate adder. In this most power consuming adder is almost the correct adder. Among all adders, the slowest and extremely efficient adder is the lower part OR adder.KeywordsApproximate computingArithmetic circuitsAdderError characteristicsEvaluation