Preface

Circuit simulation is an important tool used when designing analog electronic circuits. Circuit simulators allow new designs to be evaluated quickly and at considerably less expense than the only other alternative, fabrication. Simulation is very heavily used, particularly in the design of analog integrated circuits, with almost all circuits being simulated before being fabricated. It is also rapidly becoming more popular for the design of board level analog circuits. However, even though circuit simulators have been available for over 20 years, getting a circuit simulator to converge and give an accurate answer is still considered an art. There is considerable folklore on how to use simulators successfully; however, much of it is based on the idiosyncrasies of particular simulators or tricks that are based largely on luck. For example, one large electronics company found that convergence difficulties sometimes disappeared when the input file was reorganized and wrote a program that designers could use to randomly shuffle the simulator input file.