Basics of LC Oscillators -- Oscillator Purity Fundamentals -- Current Biased Oscillator -- Colpitts Oscillator -- Design for Low Thermal Phase Noise -- Flicker Noise -- Design for Low Flicker Phase Noise -- The Role of the Varactor.The Designer's Guide to High-Purity Oscillators presents a comprehensive theory and design methodology for the design of LC CMOS oscillators used in every wireless transmission system. The authors introduce the subject of phase noise and osciallators from the very first principles, and carry the reader to a very intuitive circuit-driven theory of phase noise in LC osciallators. The presented theory includes both thermal and flicker noise effects. Based on Hegazi, Rael, and Abidi's mechanistic theory, a sensible design methodology is gradually developed. In addition, new topologies that were recently published by the authors are discussed in detail and an optimal design methodology is presented. While the book focuses on intuition, it rigorously proves every argument to present a compact yet accurate model for predicting phase noise in LC oscillators. By so doing, the design of an LC osciallator can be handled in the same manner as an amplifier design.