A heuristic algorithm for the fanout problem

Abstract

An algorithm is presented to optimally distribute a signal to its required destinations. The choice of the buffers and the topology of the distribution tree depends on the availability of different strength gates and on the load and the required times at the destination. Since the area-constrained fanout problem is NP-complete and area is not a major consideration in present high-density designs, attention is restricted to the simpler problem of designing fast fanout circuits without any area constraint. The proposed algorithm builds the fanout tree by partitioning the fanout signals into subsets and then recursively solving each subproblem. At each stage the algorithm generates a fanout tree that is an improvement over the previous stage. This feature allows the user to specify the improvement desired by the fanout correction process. The performance of the algorithm, when run on randomly generated distributions of required times and on real design examples, is very promising.<>