A novel and useful oscillator topology demonstrating an improved
phase noise performance that exploits the time-variant
phase noise model with insights into the
phase noise conversion mechanisms. The oscillator is based on enforcing a pseudo-square
voltage waveform around an LC tank by increasing the third-
harmonic of the fundamental oscillation
voltage through an additional impedance peak. Alternatively, the oscillator is based on enforcing clipped oscillation waveform by increasing the second
harmonic of the fundamental oscillation
voltage through an additional impedance peak. This auxiliary impedance peak is realized by a
transformer with moderately coupled resonating windings. As a result, the effective impulse sensitivity function (ISF) decreases thus reducing the oscillator's effective
noise factor such that a significant improvement in the oscillator phase
noise and power efficiency are achieved.