Channel routing algorithm by free layer assignment

A new channel routing model, which allows horizontal and vertical wire segments to be placed on both layers, and two wires on a different layer to be overlapped, is presented. Based on this model, the basic constraints as well as the rules of layer assignment and routing order in two-layer channel routing are obtained. Then the property of optimal overlapping in a zone is analysed. Experimental results are very encouraging. For the famous Deutsch's difficult examples, the algorithm obtains 18 tracks solution.>