Level shifter planning for timing constrained multi-voltage SoC floorplanning

To implement multi-voltage technique in SoC designs, level shifters (LSs) are essential modules which translate signals among different voltage domains. However, inserting LSs requires non-negligible area and timing overhead. In this paper, we study LS planning (LSP) method for timing constrained multi-voltage SoC floorplanning problem. The design flow consists of two phases. In phase I, to reserve the desired white space for the placement of LSs, the netlist is modified by assigning virtual LSs in the nets. In phase II, the main floorplanning loop is implemented. Different from previous works which do voltage assignment without physical information feedback, we build an inner loop between voltage assignment and LS placement under the constraints of both timing and physical layout. Experimental results on Gigascale Systems Research Center (GSRC) benchmark suites indicate the proposed approach can improve power saving by 15% with 4% area increase.