Simplified phase noise model for negative-resistance oscillators and a comparison with feedback oscillator models

Area of Science:

• Electrical Engineering
• Physics of Oscillators

Background:

• Phase noise is a critical parameter in oscillator performance.
• Existing models for phase noise prediction can be complex.
• Oscillators utilizing negative resistance are common in various electronic applications.

Purpose of the Study:

• To develop a simplified model for predicting phase noise in negative resistance oscillators.
• To provide a clear and intuitive understanding of oscillator operation.
• To compare the phase noise performance of resonator-based oscillators with feedback oscillators.

Main Methods:

• A simplified circuit model combining noise current, negative resistance, and a resonant circuit was developed.
• The transfer function was calculated as forward trans-resistance and converted to power.
• The effect of limiting was incorporated by setting the phase noise floor to kT/2.

Main Results:

• The simplified model yields results consistent with more complex analyses.
• The model provides a clear insight into the operational principles of oscillators.
• Phase noise in resonator oscillators was found to be lower than in feedback oscillators for a given resonator power.

Conclusions:

• The simplified model offers an effective and accessible method for phase noise prediction in negative resistance oscillators.
• The study explains the reasons for the lower phase noise observed in resonator-based oscillator designs.
• Simulation and experimental validation support the model's accuracy and utility.