Improved net merging method for gate matrix layout

A net-merging method is proposed for gate-matrix layout. The method is based on a density function to calculate the minimum number of tracks necessary for the net assignment. Examples that demonstrate how this method leads to a denser gate matrix layout are included. The pitch of the gate columns is determined by the design rules, in particular, the space required to accommodate a diffused region with an internal contact window between two poly columns. In gate matrix layout, when the space between a pair of gate columns is not sufficient, the spacing between them can be increased locally to two pitches to avoid design rule violation as long as such a local change does not cause column matching problems