In this paper we address the problem of optimization of VLSI circuits to minimize power consumptioin while meeting performance goals. We present a method of estimating power consumptioin of a basic or complex CMOS gate which takes the internal cap,acitances of the gate into account. This method is used to select an ordering of series-connected transistors found in CMOS gates to achieve lower power consumption. The method is very efficient when used by library based design styles. We describe a multi-pass algorithm which makes use of transistor reordering to optimize performance and power consumption of circuits, which has a linear time complexity per pass and which converges to a solution in a small number of passes. Transformations besides transistor reordering can be used by the algorithm. The algorithm has been benchmarked on several large examples and the results are presented.

Date of this Version

October 1993