Simple tree-construction heuristics for the fanout problem

Abstract

We address in this paper the fanout tree problem introduced by Berman, et. al., that is using buffer fanout trees to reduce the fanout delay in a technology mapped network. We construct two basic types of fanout trees and provide simple techniques to manipulate them for further delay reduction. These trees are inserted along critical paths throughout the network. We also perform gate-transformation, that is substitution of a gates of equivalent logical functions, if the technology permits. Experimental results show improvement over Touati's LT-tree construction technique.