Symmetry detection for automatic analog-layout recycling

Layout symmetry is used to minimize the impact of mismatch on the performance of analog circuits. In this paper, an efficient algorithm is presented to detect automatically the mask layout symmetry. It consists of identifying signal nets, isolating circuit devices and detecting their symmetry, and finally, synthesizing the layout symmetry. Combined with layout compaction with symmetry constraints, this technique provides a methodology for automatic analog-layout recycling.