The steady downscaling of device-feature size combined with a rapid increase in circuit complexity as well as the introduction of new device concepts based on non-silicon-material systems poses great challenges for device and circuit designers. One of the major tasks is the development of new and improved device models needed for accurate device and circuit design. Another task is the development of new circuit-simulation tools to handle very large and complex circuits. This book addresses both these issues with up-to-date reviews written by leading experts in the field.The first three chapters of the book discuss advanced device models both for existing technologies and for new, emerging technologies. Among the topics covered are models for MOSFETs, thin-film transitors (TFTs), and compound semiconductor devices, including GaAs HEMTs and HFETs, heterodimensional devices, quantum-tunneling devices, as well as wide-bandgap devices. Chapters 4 and 5 discuss advanced circuit simulators that hold promise for handling circuits of much higher complexity than what is possible for typical state-of-the-art circuit simulators today.