This book describes analytical compact transistor models that can be used in circuit simulation programs like SPICE. It provides the reader with a thorough knowledge of many aspects of compact models. The book starts with the necessary device physics: Boltzmann transport equation, continuity equation, Poisson equation and physical modelling of mobility, recombination, bandgap narrowing, avalanche multiplication and noise. Then a systematic treatment of the analytical formulas that describe the device behaviour in d.c., a.c. and transient situations is given for both bipolar and MOST devices. The book contains complete sets of model equations for various models, including some new ones, and special attention is paid to the numerical problems of analytical continuity. Separate chapters are devoted to parameter determination, the parameter temperature dependence as well as their relation to process variables, the statistical correlations between parameters, the scaling rules for submicron devices, the side wall effects and the parasitics. The book thus contains all the relevant aspects of compact transistor modelling for integrated circuit design and serves as a state-of-the-art description in compact modelling. Despite the resulting progress in device optimization, the above approach fails to provide a required compact set of device design and process control rules and a compact circuit model for the analysis of large-scale electronic designs.