Design Issues in CMOS Differential LC Oscillators

A. Hajimiri and T. H. Lee

An analysis of phase noise in differential crosscoupled inductance–capacitance (LC) oscillators is presented. The effect of tail current and tank power dissipation on the voltage amplitude is shown. Various noise sources in the complementary cross-coupled pair are identified, and their effect on phase noise is analyzed. The predictions are in good agreement with measurements over a large range of tail currents and supply voltages. A 1.8-GHz LC oscillator with a phase noise of