Phase noise and accuracy in quadrature oscillators

Abstract

This paper proposes a complete analysis of quadrature-coupled LC oscillators. These oscillators operate off-resonance and for this reason, their phase noise worsens at increasing coupling strength. Since the coupling transistors raise the total power consumption, the noise-power product degrades further with respect to a stand-alone oscillator. On the other hand, at high coupling factors component mismatches affect less the phase accuracy of the quadrature outputs. Closed-form expressions for phase noise and phase accuracy are derived which are verified against circuit simulations.