Constraint-Based Dogleg Channel Routing with Via Minimization

In this article, we present an algorithm which is capable of transforming a gridded dogleg channel routing problem into a constraint programming (CP) problem. The transformed CP problem consists of a set of variables and a list of constraints; it can be solved by JaCoP, a finite-domain constraint programming solver. For a given dogleg channel routing problem, our approach is able to minimize the number of tracks and the number of vias. Although the transformed CP problems cannot be solved in polynomial time, optimal results can be found efficiently for small to medium cases. Moreover, for large cases, suboptimal results can be generated in exchange for significantly reduced execution time. As constraint programming technologies advance (e.g., parallel constraint programming), the execution time of the proposed approach can be improved. Additionally, our approach has the potential to be used in dealing with other routing problems in VLSI physical design automation.