A Heuristic to Determine Low Leakage Sleep State Vectors for CMOS Combinational Circuits

Input vector control has been used to minimize the leakage power consumption of a circuit in sleep state [1]. In this paper, we present a novel heuristic for determining a low leakage vector to be applied to a circuit in sleep state. The heuristic is a greedy search based on the controllability of nodes in the circuit and uses the functional dependencies among cells in the circuit to guide the search. Results on a set of ISCAS and MCNC benchmark circuits show that in all cases our heuristic returns a vector having a leakage within 5% ofthat of the vector obtained using an extensive random search, with orders of magnitude improvement in computational speed.