Design issues in CMOS differential LC oscillators

An analysis of phase noise in differential cross-coupled inductance-capacit ance (LC) oscillators is presented. The effect of tail current and tank pow er dissipation on the voltage amplitude is shown, Various noise sources in the complementary cross-coupled pair are identified, and their effect on ph ase noise is analyzed. The predictions are in good agreement with measureme nts over a large range of tail currents and supply voltages. A 1.8-GHz LC o scillator with a phase noise of -121 dBc/Hz at 600 kHz is demonstrated, dis sipating 6 mW of power using on-chip spiral inductors.