Accuracy-Configurable Adder for Approximate Arithmetic Designs

Approximation can increase performance or reduce power consump-tion with a simplified or inaccurate circuit in application contexts where strict requirements are relaxed. For applications related to human senses, approximate arithmetic can be used to generate suf-ficient results rather than absolutely accurate results. Approximate design exploits a tradeoff of accuracy in computation versus per-formance and power. However, required accuracy varies according to applications, and 100 % accurate results are still required in some situations. In this paper, we propose an accuracy-configurable ap-proximate (ACA) adder for which the accuracy of results is con-figurable during runtime. Because of its configurability, the ACA adder can adaptively operate in both approximate (inaccurate) mode and accurate mode. The proposed adder can achieve significant throughput improvement and total power reduction over conven-tional adder designs. It can be used in accuracy-configurable ap-plications, and improves the achievable tradeoff between perfor-mance/power and quality. The ACA adder achieves approximately 30 % power reduction versus the conventional pipelined adder at the relaxed accuracy requirement