Post-Placement Voltage Island Generation

High power consumption will shorten battery life for handheld devices and cause thermal and reliability problems. One way to lower the dynamic power consumption is to reduce the supply voltage. Multi-supply voltage (MSV) is introduced to provide higher flexibility in controlling the power and performance trade-off. In region-based MSV, circuits are partitioned into "voltage islands" where each island occupies a contiguous physical space and operates at one supply voltage. In a work by Wu et al. (2005), this supply voltage partitioning problem is addressed, and the input circuit is partitioned into a slicing structure with every voltage island rectangular in shape. This unnecessary restriction on the structure and island shapes has caused a significant degradation in the solution quality. In this paper, we propose a method to solve this voltage island generation problem without these restrictions. Experimental results have shown that our approach is fast and can improve the solution quality significantly. In some data sets, only two voltage islands are needed to satisfy the same power consumption bound while the approach by Wu et al. (2005) will generate nineteen