This book presents the basic theory and design methodology of frequency synthesizers targeted for short-range wireless applications. Three different examples of synthesizers expose the reader to several aspects of the design where advanced circuit solutions are used to improve the performance of the presented circuits. A frequency synthesizer, part of a dual-mode receiver capable of processing signals of the Bluetooth and Wireless LAN (IEEE 802.11b) standards, is implemented in BiCMOS technology. Featured in the synthesizer is a phase switching prescaler. A large capacitance is also integrated on-chip using a capacitance multiplier circuit that provides a drastic area reduction while adding a negligible phase noise contribution. The book is completed with a quadrature calibration circuit that uses an algorithm to continuously maintain phase accuracy at the output