A survey of approximate arithmetic circuits and blocks

Approximate computing has become an emerging research topic for energy-efficient design of circuits and systems. Many approximate arithmetic circuits have been proposed, therefore it is critical to summarize the available approximation techniques to improve performance and energy efficiency at a acceptable accuracy loss. This paper presents an overview of circuit-level techniques used for approximate arithmetic. This paper provides a detailed review of circuit-level approximation techniques for the arithmetic data path. Its focus is on identifying critical circuit-level approximation techniques that apply to computational units and blocks. Approximate adders, multipliers, dividers, and squarer are introduced and classified according to their approximation methods. FFT and MAC are discussed as computational blocks that employ an approximate algorithm for implementation.