A PARALLEL ALGORITHM FOR CHANNEL ROUTING-PROBLEMS

A parallel algorithm for channel routing problems is presented in this paper. The channel routing problem is very important in the automatic layout design of VLSI circuits and printed circuit boards. The problem is to route the given interconnections between two rows of terminals on a multilayer channel where the channel area must be minimized. Although several algorithms have been proposed for two-layer problems, two-layer-and-over-the-cell problems, and three-layer problems, the current advancement of VLSI chip technology allows us to use four layers composed of two metal layers and two polysilicon layers for routing in a chip. The goal of the proposed parallel algorithm is to find the near-optimum routing solution for the given interconnections in a short time. The algorithm is applied for the four-layer channel routing problems where it requires n x m x 2 processing elements for the n-net-m-track problem. The algorithm has three advantages over the conventional algorithms: 1) it can be easily modified for accommodating more than four-layer problems, 2) it runs not only on a sequential machine but also on a parallel machine with maximally n x m x 2 processors, and 3) the program size is very small. The algorithm is verified by solving seven benchmark problems where the algorithm finds routing solutions in a nearly constant time with n x m x 2 processors.