Enhanced leakage reduction technique by gate replacement

Input vector control (IVC) technique utilizes the stack effect in CMOS circuit to apply the minimum leakage vector (MLV) to the circuit at the sleep mode to reduce leakage. Additional logic gates can be inserted as control points to make it more effective. In this paper, we propose a gate replacement technique that further enhances the leakage reduction. The basic idea is to replace a gate that is in its worst leakage state by another library gate while keeping the circuit's correct functionality at the active mode. We also develop a divide-and-conquer approach that integrates a fast gate replacement heuristic, an optimal MLV search strategy for tree circuit, and a genetic algorithm to connect the tree circuits. We conduct experiments on the MCNC91 benchmark circuits. The results reveal that our technique can reduce additional 10% to 24% leakage over the best known IVC methods and the optimal MLV with no delay penalty and little area increase.