Power reduction by gate sizing with path-oriented slack calculation

Abstract

This paper describes methods for reducing power consumption. We propose using gate sizing technique to reduce power for circuits that have already satisfied the timing constraint. Replacement of gates on noncritical paths with smaller templates is used in reducing the dissipated power of a circuit. We find that not only gates on noncritical paths can be down-sized, but also gates on critical paths can be down-sized. A power reduction algorithm by means of single gate resizing as well as multiple gates resizing will be proposed. In addition, to identify gates to be resized, a path-oriented method in calculating slack time with false path taken into consideration will be also proposed. During the slack time computation, in order to prevent long false path from becoming sensitizable and thus increasing the circuit delay, slack constraint will be set for gales. Results on a set of circuits from MCNC benchmark set demonstrate that our power reduction algorithm can reduce about 10% more power, on the average, than a previously proposed gate sizing algorithm.