Low-phase-noise VCO with active resonator

The phase noise of an oscillator tuned by an Active Resonator is compared to the phase noise of a Varactor-Tuned Oscillator, and to that of a fixed-frequency, Dielectric Resonator Oscillator for comparison. The three oscillators share the same active device and output network, and differ for the resonator only. The Active Resonator is composed of an active inductor for low losses and high Q-factor, and of a varactor for tunability. The active-resonator oscillator has better phase noise and slightly lower tunability with respect to the varactor-tuned oscillator, and slightly worse phase noise than the dielectric-resonator oscillator.