Phase-noise Reduction Through an External High-Q Network Using a Black-Box Oscillator Model

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 reduced-order 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) Mini-Circuits ROS-3000-819+ (2-3GHz) obtaining a phase-noise reduction of about 10 dB with respect to the free-running values.