Frequency Precision of Oscillators Based on High-Q Resonators

TL;DR

This paper introduces a method to analyze and improve the phase noise and frequency precision of oscillators based on high-Q resonators by deriving phase drift expressions and proposing measurement schemes.

Contribution

It provides a novel analytical framework for phase noise analysis in high-Q resonator oscillators and suggests ways to enhance frequency stability through nonlinear tuning.

Findings

Derived general expressions for phase drift due to noise sources.

Proposed a measurement scheme for feedback noise in oscillators.

Illustrated results with a phenomenological amplifier model.

Abstract

We present a method for analyzing the phase noise of oscillators based on feedback driven high quality factor resonators. Our approach is to derive the phase drift of the oscillator by projecting the stochastic oscillator dynamics onto a slow time scale corresponding physically to the long relaxation time of the resonator. We derive general expressions for the phase drift generated by noise sources in the electronic feedback loop of the oscillator. These are mixed with the signal through the nonlinear amplifier, which makes them {cyclostationary}. We also consider noise sources acting directly on the resonator. The expressions allow us to investigate reducing the oscillator phase noise thereby improving the frequency precision using resonator nonlinearity by tuning to special operating points. We illustrate the approach giving explicit results for a phenomenological amplifier model. We also propose a scheme for measuring the slow feedback noise generated by the feedback components in an open-loop driven configuration in experiment or using circuit simulators, which enables the calculation of the closed-loop oscillator phase noise in practical systems.