A new global router using zero-one integer linear programming techniques for sea-of-gates and custom logic arrays

A global routing method is proposed for sea-of-gates (SOG) arrays and custom logic arrays based on a zero-one linear integer programming technique. This method overcomes the various difficulties due to numerous physical constraints faced by many heuristic routing algorithms. In the proposed approach, all the physical constraints are rigorously modeled in the constraint equations. Alternatives for all the nets are considered simultaneously with the routing environment, instead of being routed in a particular net-ordering. An optimal set of global paths routing all the nets is found with well established zero-one linear integer programming methods. The global router has run successfully on industrial SOG circuits, including 108,000 transistor circuits with 9400 nets, achieving 100% routing and high packing densities, which compare favorably with recently reported results