Power switch network design for MTCMOS

Multithreshold CMOS (MTCMOS) has been a proven methodology to reduce leakage power in DSM designs. Previously lumped sleep transistors were designed for worst case condition, and hence occupied a large area. To reduce the area, cluster based sleep transistor design was proposed which takes into account simultaneous switching within the circuit blocks. We propose an improved method of clustering the sleep transistors by taking on chip decoupling capacitances into account. With the proposed heuristic, we are able to obtain sleep transistor area reduction of 64% with respect to conventional clustering methodology. The leakage current reduction for the circuit blocks is in the order of 2000× to 8000× with respect to the ones without sleep transistors. We propose gate clustering based on ATPG vectors to handle large design. The experimental results are shown for ISCAS´85 benchmarks.