A New Approach for Combining Yield and Performance in Behavioural Models for Analogue Integrated Circuits

A new algorithm is presented that combines performance and variation objectives in a behavioural model for a given analogue circuit topology and process. The tradeoffs between performance and yield are analysed using a combination of a multi-objective evolutionary algorithm and Monte Carlo simulation. The results indicate a significant improvement in overall simulation time and efficiency compared to conventional simulation based approaches, without a corresponding drop in accuracy. This approach is particularly useful in the hierarchical design of large and complex circuits where computational overheads are often prohibitive. The behavioural model has been developed in Verilog-A and tested extensively with practical designs using the Spectretrade simulator. A benchmark OTA circuit was used to demonstrate the proposed algorithm and the behaviour has been verified with transistor level simulations of this circuit and a higher level filter design. This has demonstrated that an accurate performance and yield prediction can be achieved using this model, in a fraction of the time of conventional simulation based methods.