Over-the-cell routing with cell orientations consideration

Existing over-the-cell channel routers assume that the orientations of the cells are fixed. In practice, it is quite common that each cell can be horizontally flipped. This pin rearrangement flexibility should be used by over-the-cell routers to further reduce channel routing area. Given a placement of cells in multiple rows with pin terminals at the top and bottom edges and each cell can be flipped. The objective is to select an orientation for each cell and a set of net segments to be routed over the cells such that the final routing area is minimized. We present an optimal algorithm to maximize the total weights of the net segments to be routed in over-the-cell routing regions