Analysis of Power Efficiency in High-Performance Class-B Oscillators

This paper presents an analysis of power efficiency in LC voltage-controlled oscillators (VCOs). Three different class-B topologies are compared under different operating conditions, demonstrating that the CMOS oscillator embedding two tail resonators achieves the best power efficiency and, consequently, best phase-noise-versus-power trade-off. A 65-nm CMOS prototype in post-layout simulations achieves a phase noise of -159 dBc/Hz at 20-MHz offset from the 3.6-GHz carrier, while dissipating 4.5 mW from 1.2-V power supply and covering 21.8% tuning range.