A new approach to the pin assignment problem

In this paper we study a pin assignment problem for macro-cells which is motivated by the goal of integrating the placement and routing steps in the physical design of VLSI circuits. We assume that the macro-cells have already been placed. In the mean time, we assume that the design of the macro-cells is still “soft” in that although the pins in a cell have a fixed relative order, they can be shifted around the boundary of the cell. A new algorithm was developed to determine the optimal shiftings of the pins so that a weighted sum of the lengths of the connecting wires is minimum. Good experimental results were obtained.