Phase-noise reduction through an external high-Q network using a black-box oscillator model

Abstract

A method is presented to minimize the phase noise of an existing oscillator when connected to an external high-Q network. It relies on the experimental extraction of a reducedorder model of the original free-running oscillator, which involves a characterization of its pulling effects. With this model it is possible to predict the solution curves, stability properties and phase-noise of the augmented oscillator. It enables the optimization of the high-Q network to maximize the phase-noise reduction at a stable operation point in a single valued section of the solution curve. The method has been applied to (VCO) MiniCircuits ROS-3000-819+ (2-3GHz) obtaining a phase-noise reduction of about 10 dB with respect to the free-running values.