Multiphase LC Oscillators

This paper proposes an extensive analysis of multiphase LC oscillators. N oscillators coupled in a ring topology can generate multiphase outputs. For their nature, these oscillators operate off-resonance and consequently their phase noise worsens at increasing coupling strength. Since the coupling transistors raise the total power consumption, the noise-power product degrades even more with respect to a stand-alone oscillator. On the other hand, at high coupling factors, component mismatches affect less the phase accuracy. Closed-form expressions for phase noise and phase accuracy are derived which are verified against circuit simulations.