Switch bound allocation for maximizing routability in timing-driven routing of FPGAs

Abstract

In segmented channel routing of row-based FPGAs, the routability and interconnection delays depend on the choice of the upper bounds on the number of programmable switches used in routing net segments in the channel. Traditionally, the upper bounds for the net segments in the same channel are set uniformly. In this paper, we present algorithms for determining the upper bounds for all net segments of a net simultaneously, so that the predefined source-to-sink delay bound on the net is satisfied and the routability of the net is maximized. The upper bounds on net segments in a channel thus in general are non-uniform. Preliminary experimental results show that the algorithms can significantly improve routability and reduce delay bound violation as compared with the traditional approach.