Cooperative approach to a practical analog LSI layout system

A system for analog LSI layout design is developed based on a human-computer cooperative approach. It can handle the many layout constraints which ensure circuit functionality. The system integrates expert knowledge with chip minimization algorithms. It consists of a rule-based layout constraint extractor, a floor planner based on a block size estimation technique, cell placement based on the circuit diagram, a grid-free maze router, rule-based layout improvement, and a space expansion router that meets the requirement for high wireablity while satisfying complex constraints. This system is applied to several actual analog LSIs for signal processing and the DC/AC parameters of the fabricated chips are evaluated. Close matching with simulated circuits demonstrates that this system meets the requirements for practical usage.