Exploration of approximate multipliers design space using carry propagation free compressors.

Many emerging application domains, such as machine learning, can tolerate limited amounts of arithmetic inaccuracy. When designing custom compute accelerators for these domains, hardware designers can explore tradeoffs that sacrifice accuracy in order to reduce area, delay, and/or power consumption. This paper explores the design space of approximate multipliers using a family of approximate compressors as building blocks for the partial product reduction tree. We present a tool that allows the user to specify an allowable level of error tolerance, and returns the minimum area, delay, or power approximate multiplier that provides that level of accuracy. Our experimental results indicate that our proposed compressors generate more accurate and more efficient approximate multipliers than existing state-of-the-art techniques.