Simulation and Behavioral Modeling

Abstract

Simulation with accurate and realistic models has been an invaluable tool for the verification of the electrical performance of integrated circuits. Simulators hold a particularly important place in the world of analog and mixed-signal design tools. Primarily, they verify that the circuit as designed will perform as expected. They are also used in design space exploration. It is most important that a simulator be trustworthy, but it is also important that the simulator be fast and robust. When designing very high-performance circuits, accurate prediction of the time and frequency-domain behavior of the circuit is needed. Such prediction can only be achieved by the use of circuit simulators that analyze detailed waveforms. These simulators (e.g. SPICE [217][248]) can provide accurate results, but sometimes at the expense of very long (possibly unaffordable) computing time. In particular, when complex analog and mixed-signal systems are being designed, accurate circuit simulation of the entire circuit is out of the question. The complexity in terms of the number of components, and of the types of analyses makes the use of SPICE too time consuming. Moreover, it may not be possible to use a circuit simulator to make design “decisions” at the “higher” levels in a top-down design process, because the detailed circuit implementations of the sub-blocks may not be available at that particular level of the design hierarchy.