ABSTRACT
This chapter deals with the simulation or analysis of a nonlinear electrical circuit by means of a computer program. The program creates and solves the differential-algebraic equations of a model of the circuit. The basic tools in the solution process are linearization, difference approximation, and the solution of a set of linear equations. The output of the analysis may consist of (1) all node and branch voltages and all branch currents of a bias point (dc analysis), (2) a linear small-signal model of a bias point that may be used for analysis in the frequency domain (ac analysis), or (3) all voltages and currents as functions of time in a certain time range for a certain excitation (transient analysis). A model is satisfactory if there is good agreement between measurements and simulation results. In this case, simulation may be used instead of measurement for obtaining a better understanding of the nature and abilities of the circuit. The crucial point is to set up a model that is as simple as possible, in order to obtain a fast and inexpensive simulation, but sufficiently detailed to give the proper answer to the questions concerning the behavior of the circuit under study. Modeling is the bottleneck of simulation.
