A High-Density Multilayer PCB Router Based on Necessary and Sufficient Conditions for Single Row Routing

This paper presents the necessary and sufficient conditions for routability of a list of two-point nets to be wired in a single row without using vias (single row routing) in a different formulation from that in [9]. These conditions are expressed in terms of left and right block counts (number of left and right blockages that will be encountered by each net if all nets in the list are routed in the same channel) of nets in the net list. An efficient routing algorithm which exploits these necessary and sufficient conditions is presented. Experimental results demonstrating the effectiveness of this algorithm are also given. Possible practical applications exploiting this set of necessary and sufficient conditions are suggested.