LAYGEN II—Automatic Layout Generation of Analog Integrated Circuits

This paper describes an innovative design automation tool, LAYGEN II, for analog integrated circuit (IC) layout generation based on template descriptions and on evolutionary computation techniques. LAYGEN II was developed giving special emphasis to the reusability of expert knowledge and to the efficiency of retargeting operations. The designer specifies the sized circuit-level structure, the required technology and also, the layout template consisting of technology and specification independent high-level layout guidelines. For placement, the topological relations present in the template are extracted to a nonslicing B*-tree layout representation, and the tool automatically merges devices and improves the floorplan quality. For routing an optimization kernel consisting of a tailored version of the multiobjective multiconstraint evolutionary algorithm NSGA-II is used. The Router optimizes all nets simultaneously and uses a built-in engine to evaluate each of the layout solutions. The automatic layout generation is demonstrated here using the LAYGEN II tool for typical analog circuit structures, and the results in GDSII format were validated using the industrial grade verification tool Calibre®.