Voltage and Level-Shifter Assignment Driven Floorplanning

Bei YU  Sheqin DONG  Song CHEN  Satoshi GOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A   No.12   pp.2990-2997
Publication Date: 2009/12/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.2990
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
Category: Physical Level Desing
voltage-island,  voltage assignment,  convex network flow,  level shifter assignment,  white space redistribution,  

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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.