Decoupling capacitance allocation and its application to power-supply noise-aware floorplanning

Abstract

We investigate the problem of decoupling capacitance (decap) allocation for power supply noise suppression at floorplan level. First, we assume that a floorplan is given and consider the decap placement as a postfloorplan step. Second, we consider the decap placement as an integral part of a floorplanning methodology (noise-aware floorplanning). In both cases, the objective is to minimize the floorplan area while suppressing the power supply noise below the specified limit. Experimental results on MCNC benchmark circuits show that, for postfloorplan decap placement, the white space allocated for decap is about 6%-9% of the chip area for the 0.25-/spl mu/m technology. The power-supply noise is kept below the specified limit. Compared to postfloorplan approach, the peak power-supply noise can be reduced by as much as 40% and the decap budget can be reduced by as much as 21% by using noise-aware floorplanning methodology. The total area is also reduced due to the reduced total decap budget gained from reduced power supply noise.