High-level simulation of substrate noise generation including power supply noise coupling

Substrate noise caused by large digital circuits will degrade the performance of analog circuits located on the same substrate. To simulate this performance degradation, the total amount of generated substrate noise must be known. Simulating substrate noise generated by large digital circuits is however not feasible with existing circuit simulators and detailed substrate models due to the long simulation times and high memory requirements. We have developed a methodology to simulate this substrate noise generation at a higher level. Not only does this methodology take noise coupling from switching gates into account, but also noise coupling from the power supply is included. This paper describes this simulation methodology. In the paper it is shown that the high-level simulations correspond very well with SPICE simulations and that a large gain in simulation speed is obtained. This high-level simulation methodology makes it possible to predict substrate noise generation of large digital circuits in a very efficient way, early in the design how of mixed-signal ASICs.