Piecewise approximate circuit simulation

Conventional circuit simulation methods are inflexible and slow, especially for large circuits. Piecewise approximate circuit simulation, an alternative that can be more efficient and allows variable accuracy in the simulation process, is discussed. Thus, the tradeoff between accuracy and CPU time is in the hands of the user. SPECS (simulation program for electronic circuits and systems) is the prototype implementation of a piecewise approximate, tree/link based, event driven, variable accuracy circuit simulation algorithm that uses table models for device evaluation. The models can be built at various levels of accuracy, and concomitant levels of precision are reflected in the simulation results. SPECS has been benchmarked on some large, industrial circuits and has proven to be an efficient and reliable simulator. However, it suffers a penalty in run time while simulating stiff circuits, or circuits with a wide range of time constants. The authors present enhanced algorithms used in SPECS to ensure efficient steady-state computation for stiff circuits. >