Cell-based layout techniques supporting gate-level voltage scaling for low power

Gate-level voltage scaling is an approach that allows different supply voltages for different gates in order to achieve power reduction. Previous research focused on determining the voltage level for each gate and ascertaining the power-saving capability of the approach via logic-level power estimation. In this paper, we present cell-based layout techniques that make the approach feasible. We first propose a new block layout style and a placement strategy to support the voltage scaling with conventional standard cell libraries. Then we propose a new cell layout style with built-in multiple supply rails so that gate-level voltage scaling can be immediately embedded in a typical cell-based design flow. Experimental results show that proposed techniques maintain good power benefit while introducing moderate layout overhead.