Topology synthesis of analog circuits based on adaptively generated building blocks

This paper presents an automated analog synthesis tool for topology generation and subsequent circuit sizing. Though sizing is indispensable, the paper mainly concentrates on topology generation. A new kind of GA is developed, where a fraction of the offsprings in each generation is built from building blocks or cells obtained from previous generations. The cells are stored in a hierarchically arranged library that also contains information on the preferred neighborhood of each cell. The adaptively formed cell library starts only with basic elements and gradually includes functionally useful and bigger blocks, pertinent to the design. The techniques have been applied to synthesize an operational amplifier and a ring oscillator design. Results show that with reasonable computational effort, topologies have evolved that are designer understandable.