Employing a Relay-Feedback Oscillator for Resonance Tracking

Many applications require a controller to automatically track the resonant frequency of a given resonator. Unlike conventional relay-feedback schemes that use a single relay or saturated amplifier in a feedback loop with the resonator, the proposed scheme employs a relay-feedback oscillator for resonance tracking. To facilitate design and analysis, linearized models for the frequency dynamics of both schemes have been developed. Interestingly, the relay-feedback scheme, despite its name, is actually an open-loop scheme for resonance tracking. On the other hand, the proposed scheme has an inherent feedback mechanism for resonance tracking, leading to better noise rejection and frequency stability.