IMPROVED LEFT EDGE CHANNEL ROUTER.

A new channel routing algorithm is presented which is not only simple and fast, but also highly effective. It assumes that pins and wires lie on a common grid in a two layer channel, and that vertical wires are on one layer, horizontal wires on the other. The router processes the channel in a same way as 'left edge' algorithm, that is, in a top-to-bottom, row-by-row manner. To improve solutions, it assigns a weight to each net and calculates an optimum net assignment for each row. The assignment can be obtained by a longest path algorithm. The algorithm was implemented for examples in previously published papers. Experimental results show that the new algorithm produces optimum solutions in most cases.