Circuit simulation has become an essential tool in electronic circuit design. Analogue and mixed-signal IC design would, otherwise, be impossible. The applicability and limitations of circuit simulators are not, however, well understood. This book explains the algorithms used in circuit simulation, the numerical techniques needed for linear and nonlinear DC analysis, transient analysis and AC analysis are explained in detail. The numeric methods are then extended to include sensitivity and tolerance analysis and optimization of component values for circuit design. Logic simulation and mixed signal simulation algorithms are explained in the final two chapters. The book contains detailed descriptions of the numerical methods used. The aim is to give experienced users of circuit simulators an insight into the algorithms so that they can make the best use of the various analysis methods. At the same time, the book will provide a comprehensive grounding for engineers who wish to develop models for existing simulators or who wish to develop new simulators.