Sudip K. Nag

Performance-driven simultaneous placement and routing for FPGA's

Sequential place and route tools for field programmable gate arrays (FPGAs) are inherently weak at addressing both wirability and timing optimizations. This is primarily due to the difficulty of accurately predicting wirability and delay during placement. A set of new performance-driven simultaneous placement/routing techniques has been developed for both row-based and island-style FPGA designs. These techniques rely on an iterative improvement placement algorithm augmented with fast, complete routing heuristics in the placement loop. For row-based designs, this new layout strategy yielded up to 28% improvements in timing and 33% in wirability for several MCNC benchmarks when compared to a traditional sequential place and route system in use at Texas Instruments. On a set of industrial designs for Xilinx 4000-series island-style FPGAs, our scheme produced 100% routed designs with 8-15% improvement in delay when compared to the Xilinx XACT5.0 place and route system.

Post-placement residual-overlap removal with minimal movement

In this paper we present a novel approach for removing residual overlaps among blocks. We start out by representing the placement in the sequence pair form and describe transformations to the sequence pair to make the placement feasible. This is followed by a distance-based slack allocation to generate a new placement with no overlaps, while being as close to the original placement as possible. Our results demonstrate the efficacy of our approach in transforming layouts with overlaps to overlap-free layouts with minimal object movement.