Voltage Island Generation in Cell Based Dual-Vdd Design

Yici CAI  Bin LIU  Qiang ZHOU  Xianlong HONG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.1   pp.267-273
Publication Date: 2007/01/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.1.267
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: VLSI Design Technology and CAD
dual-Vdd,  layout,  placement,  voltage island,  voltage assignment,  

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The voltage island style has been widely accepted as an effective way to design low power high performance chips. This paper proposes an automated voltage island generation flow in standard cell based designs. Two important objectives in voltage island designs are addressed in this flow: 1) reducing power dissipation under given performance constraints; 2) reducing implementation overheads, mainly layout overheads caused by cell clustering to form islands. The first objective is handled with timing and power driven netweighting and timing analysis in voltage assignment. For the second objective, we propose layout aware voltage assignment, i.e., voltage assignment during placement. We iteratively perform the following to adjustments: adjustment on voltage assignment to facilitate voltage island generation, and adjustment on cell locations to cluster cells in voltage islands. These iterations lead to a flow featured with tightly integrated voltage assignment and cell placement. Experimental results have demonstrated the advantages of our approach.