BUFFER INSERTION TO REDUCE WIRELENGTH IN VLSI CIRCUITS

Wirelength in a net of an integrated circuit design is reduced by forming clusters of sinks to be interconnected, inserting a buffer at each cluster, and providing branch connections between clusters by connecting a sink of one cluster to a buffer of another cluster, to create a buffer tree spanning all sinks. The buffers are inserted at a point on a respective bounding box of a cluster that is closest to a source for the net. A sink that provides a branch connection to the buffer of another cluster is the closest sink to that buffer (except for those sinks in the cluster). Clusters may be formed by examining different pairs of the sinks with different bounding boxes, and identifying one of the pairs whose bounding box has a lowest half-perimeter as the best pair for clustering.