EPNR: an energy-efficient automated layout synthesis package

This paper reports our experiences with incorporating energy (or switched capacitance) based algorithms into an automated layout synthesis system based on standard cells. Our experimental results show an average savings of 18.5% in interconnect energy at a cost of about 6.2% area increase relative to area-minimized layouts on MCNC Logic Synthesis '93 benchmarks. The basic premise is that the wires with high switching should be made short even if it involves stretching several low switching wires. We modified an existing layout system, VPNR, to include these techniques during the placement and global routing phases. Attempts to include switching probabilities into channel routing did not produce appreciable results. Our experiments also lend insight into the composition of the solution space for VLSI energy minimization problems.