Physical synthesis for FPGA interconnect power reduction by dual-Vdd budgeting and retiming

Abstract

Field programmable dual-Vdd interconnects are effective in reducing FPGA power. We formulate the dual-Vdd-aware slack budgeting problem as a linear program (LP) and a min-cost network flow problem, respectively. Both algorithms reduce interconnect power by 50% on average compared to single-Vdd interconnects, but the network-flow-based algorithm runs 11x faster on MCNC benchmarks. Furthermore, we develop simultaneous retiming and slack budgeting (SRSB) with flip-flop layout constraints in dual-Vdd FPGAs based on mixed integer linear programming, and speed-up the algorithm by LP relaxation and local legalization. Compared to retiming followed by slack budgeting, SRSB reduces interconnect power by up to 28.8%.