We describe a hierarchical structure for a knowledge-based analog circuit synthesis tool. Analog circuit topologies are represented as a hierarchy of abstract functional blocks each with associated design knowledge. We also describe mechanisms to select from among alternate design styles, and to translate performance specifications from one level in the hierarchy to the next lower level. A prototype implementation, OASYS, synthesizes sized transistor schematics for CMOS operational amplifiers and comparators from a set of performance specifications and process parameters. We describe the role such a synthesis system can play in exploring the space of designable circuits. And finally, we briefly describe other related research in analog synthesis at Carnegie Mellon, including OASYSVM, which facilitates the addition of new design topologies to the framework, and ANAGRAM, the counterpart to OASYS, which performs the circuit schematic to physical layout phase of analog circuit design 1. In...

This paper introduces an automated circuit design system for the evolution and subsequent invention of CMOS amplifiers. The proposed system relies on a mix of genetic programming and a new topologyindependent design optimisation method referred to as current-flow analysis. Genetic programming evolves new circuit topologies from the collection of primitive devices and basic building blocks. Current-flow analysis screens and corrects circuits using topology-independent design rules. Experimental results show a promising improvement on the design of operational amplifiers that making the automated analogue design environment using genetic programming a lot more practical. I.