Timing-driven placement for FPGAs

ABSTRACTIn this paper we introduce a new Simulated Annealing-based timing-driven placement algorithm for FPGAs. This paper has three main contributions. First, our algorithm employs a novel method of determining source-sink connection delays during placement. Second, we introduce a new cost function that trades off between wire-use and critical path delay, resulting in significant reductions in critical path delay without significant increases in wire-use. Finally, we combine connection-based and path-based timing-analysis to obtain an algorithm that has the low time-complexity of connection-based timing-driven placement, while obtaining the quality of path-based timing-driven placement.A comparison of our new algorithm to a well known non-timing-driven placement algorithm demonstrates that our algorithm is able to increase the post-place-and-route speed (using a full path-based timing-driven router and a realistic routing architecture) of 20 MCNC benchmark circuits by an average of 42%, while only increasing the minimum wiring requirements by an average of 5%.