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 different layers 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 analyzed. For the example used, this algorithm obtains 18 tracks solution.>