An H-V alternating router

An H-V alternating router based on the concurrent H (horizontal) and V (vertical) tile expansions is presented. The router is modeled by a sequence of alternating H and V corner-stitching space tiles, where the expansion direction is controlled by a heuristic evaluation function using the A* technique and the damping concept. Tile growing is governed by the following three factors: constrained expansion area, limited expansion depth, and oriented expansion direction. All the H-V tile expansion operations can be easily performed on a specially designed net-forest structure. It is shown that this approach generates nearly optimal connection paths with a minimum number of bends and always guarantees a feasible solution if such a path exists. The performance of this router is better than that of H-only tile-expansion routers. This router is also well suited for wiring hierarchical modules with the metal-metal matrix technology and can be extended to multilayer layouts