MCG: A multilayer general area MCM routing algorithm.

Abstract

A new multilayer, general-area, multichip module (MCM) routing algorithm, called MCG, is introduced. The algorithm differs from other MCM routers in the way that the routes interconnecting the nets are constructed. Some routers perform the routing net-by-net and others extend the routes piece by piece during the routing process. The MCG router takes a more global approach by constructing a small number of candidate routes for each net, building a compatibility graph for the candidate routes and reducing the graph to yield a routing solution. Due to this unique way of performing the routing, the MCG router offers several outstanding features. First, it performs the routing of the nets simultaneously. Therefore it is not subject to the net ordering problem. Second, it can give the designer the flexibility of selecting the topology of routes for the nets to be routed, which is almost impossible for other algorithms. Third, it offers a natural way to incorporate the electrical constraints into the routing process, which is absent or hard to handle in other algorithms. The timing constraint can be incorporated easily by constructing the candidate routes of the net according to the requirements of the design; and the compatibility test of the candidate routes can be used to estimate the crosstalk between the routes from different nets, which make the crosstalk estimation more sophisticated than the other techniques. Compared with other MCM routers, the MCG router produces better quality routing solutions in terms of number of layers, number of vias, total wire length and routing density. In addition to the application in the area of MCM routing, the MCG algorithm can also be applied to high density PCB routing problems.