Rule based CAD tools for analog circuit synthesis and layout compilation

A design methodology has been developed to replace the conventional cut-and-try procedure with a deterministic rule-based design approach utilizing small and large signal models and characterization data tables. An operational amplifier design automation tool is used as an example. The results show design flexibility and effectiveness allowing a user-friendly interface with high design credibility and extended analysis. The design expertise is resident in rules determining device sizes in predefined topologies in a manually optimized graphic library of sub-cells and in data tables collected in the sub-cell characterization process. The CAD tool offers wide applicability. Various operational amplifier design examples are given to demonstrate its versatility.