Delay abstraction in combinational logic circuits

Abstract

In this paper we propose a data structure for abstracting the delay information of a combinatorial circuit. The particular abstraction that we are interested in is one that preserves the delays between all pairs of inputs and outputs in the circuit. The proposed graphical data structure is of size proportional to (m+n) in best case, where m and n refer to the number of inputs and outputs of the circuit. In comparison, a delay matrix that stores the maximum delay between each input/output pair has size proportional to m/spl times/n. We present heuristic algorithms for deriving these concise delay networks. Experimental results shows that, in practice, we can obtain concise delay network with the number of edges being a small multiple of (m+n).