This book explores integrated gate drivers with emphasis on new gallium nitride (GaN) power transistors, which offer fast switching along with minimum switching losses. It serves as a comprehensive, all-in-one source for gate driver IC design, written in handbook style with systematic guidelines. The authors cover the full range from fundamentals to implementation details including topics like power stages, various kinds of gate drivers (resonant, non-resonant, current-source, voltage-source), gate drive schemes, driver supply, gate loop, gate driver power efficiency and comparison silicon versus GaN transistors. Solutions are presented on the system and circuit level for highly integrated gate drivers. Coverage includes miniaturization by higher integration of subfunctions onto the IC (buffer capacitors), as well as more efficient switching by a multi-level approach, which also improves robustness in case of extremely fast switching transitions. The discussion also includes a concept for robust operation in the highly relevant case that the gate driver is placed in distance to the power transistor. All results are widely applicable to achieve highly compact, energy efficient, and cost-effective power electronics solutions.