LADIES: an automatic layout system for analog LSI´s

The authors have developed a prototype system for analog LSI layout design which ensures the functionality of circuits. The procedural initial layout program is based on a clustering algorithm and a river routing algorithm and it manipulates mathematically specified layout constraints. Before and after this program the system uses a knowledge base to manipulate complex conditions and thereby avoid circuit malfunction. Using circuit descriptions and knowledge about layout constraints as related to the circuits, a preprocessing program generates specific layout constraints which ensure the functionality of circuits. A postprocessing program eliminates unused space, taking the various constraints into account. The authors have also developed a predictive inference mechanism which selects suitable actions to get better results. In an experiment involving a 71-element block, the authors obtained a layout which follows all constraints and is only 8% larger than the manual layout.<>