Exact required time analysis via false path detection

Abstract

This paper addresses how to compute required times at intermediatenodes in a combinational network given required times atprimary outputs. The simplest approach is to compute them basedon topological delay analysis without any consideration of falsepaths. In this paper, however, we take into account false pathsbetween the intermediate nodes and the primary outputs explicitlyto characterize the timing constraints at the nodes more accurately.We show that this approach leads to a technique for computing amore refined and relaxed timing constraint than that obtained bytopological analysis. We generalize the notion of required timesfrom a single constant to a relation where a signal is required atdifferent times depending on the values of the other signals.