Efficient Algorithms for Wiring Channels with Movable Terminals

A problem of wiring a channel of movable terminals in a VLSI chip is presented. Two subproblems are addressed: maximum alignment and wireable placement. Maximum alignment is to reassign terminal positions in the channel in order to maximize the number of nets that can be implemented as straight connections. Wireable placement is to find an assignment of the movable terminals to the vertical tracks in the channel. The assignment must eliminate the vertical conflicts between nets. We impose a restriction on the number of unconnected terminals in the maximum alignment problem. The restriction ensures that the number of columns in the channel is not increased in the process. This restriction is not addressed in previous works which considered the maximum alignment problem. The two subproblems are solved using two heuristic algorithms. Some well-known examples, including Deutsch’s difficult example, are used as test cases to study our algorithms. The results show that both channel width and via usage are reduced significantly by using our procedures.