Sequential logic optimization for low power using input-disabling precomputation architectures

Abstract

Precomputation is a recently proposed logic optimization technique which selectively disables the inputs of a logic circuit, thereby reducing switching activity and power dissipation, without changing logic functionality. In sequential precomputation, output values required in a particular clock cycle are selectively precomputed one clock cycle earlier, and the original logic circuit is "turned off" in the succeeding clock cycle. We target a general precomputation architecture for sequential logic circuits, and show that it is significantly more powerful than the architecture previously treated in the literature. The very power of this architecture makes the synthesis of precomputation logic a challenging problem. We present a method to automatically synthesize precomputation logic for this architecture. Up to 66% reduction in power dissipation is possible using the proposed architecture. For many examples, the proposed architecture result in significantly less power dissipation than previously developed methods.