Using logic duplication to improve performance in FPGAs

Abstract

The purpose of this paper is to introduce a modified packing and placement algorithm for FPGAs that utilizes logic duplication to improve performance. The modified packing algorithm was designed to leave unused basic logic elements (BLEs) in timing critical clusters, to allow potential targets for logic duplication. The modified placement algorithm consists of a new stage after placement in which logic duplication is performed to shorten the length of the critical path. In this paper, we show that in a representative FPGA architecture using .18 mm technology, the length of the final critical path can be reduced by an average of 14.1%. Approximately half of this gain comes directly from the changes to the packing algorithm while the other half comes from the logic duplication performed during placement.