  Low Power Design has become a significant requirement when the CMOS
technology entered the nanometer era. Multiple-Supply Voltage (MSV) is a
popular and effective method for both dynamic and static power reduction while
maintaining performance. Level shifters may cause area and Interconnect Length
Overhead (ILO), and should be considered at both floorplanning and
post-floorplanning stages. In this paper, we propose a two phases algorithm
framework, called VLSAF, to solve voltage and level shifter assignment problem.
At floorplanning phase, we use a convex cost network flow algorithm to assign
voltage and a minimum cost flow algorithm to handle level-shifter assignment.
At post-floorplanning phase, a heuristic method is adopted to redistribute
white spaces and calculate the positions and shapes of level shifters. The
experimental results show VLSAF is effective.
