Exact and heuristic approaches to input vector control for leakage power reduction

Abstract

We present two approaches to leakage power minimization in static CMOS circuits by means of input vector control (IVC). We model leakage effects using pseudo-Boolean functions. These are incorporated into an optimal integer linear programming model called VG-ILP that analyzes leakage variation with respect to a circuit's input vectors. A heuristic mixed-integer linear programming (MLP) method is also presented which has several advantages: it is faster, its accuracy can be quickly estimated, and trade-offs between runtime and optimality can easily be made. The proposed methods are used to generate a large set of experimental results on leakage reduction. It is shown that average leakage currents are usually 1.25 times the minimum, confirming the effectiveness of IVC. The heuristic MLP approach is much faster than exact ILP, while finding input vectors whose power consumption is only a few percent from the optimum.