TimberWolf3.2: A New Standard Cell Placement and Global Routing Package

Abstract

TimberWolf3.2 is a new standard cell placement and global routing package. The placement and global routing proceed over 3 distinct stages. The general combinatorial optimization technique known as simulated annealing is used during the first two stages of the placement. In the first stage, TimberWolf3.2 places the cells such that the total estimated interconnect cost is minimized. During the second stage, TimberWolf3.2 inserts feed through cells as required and the minimization of the total estimated interconnect cost proceeds again in the manner of simulated annealing. The second stage comes to a close following a global routing step, in which the number of wiring tracks needed is accurately estimated. During the third and final stage, local changes are made to the placement whenever such changes result in a reduction in the number of wiring tracks required. TimberWolf3.2 has achieved area savings ranging from 15 to 75% in experiments on numerous industrial circuits.