Mechanical Resonator Tuning with Phase-Shift Feedback and LC Control
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Solution Overview
Problem
Conventional electromechanical oscillators have limited tuning accuracy due to manufacturing tolerances and environmental variations, which restrict their ability to maintain a desired resonance frequency.
Innovation Solution
Incorporating a phase shifter in a feedback loop with the mechanical resonator and an LC tuning subcircuit that includes a variable capacitor or inductor to adjust the resonance frequency, allowing tuning on both sides of the series resonance peak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tuning methods are used with mechanical resonators, then the oscillator can be tuned within a limited range between series and parallel resonance peaks, but the tuning accuracy around the series resonance frequency is limited
Solution Approach 1:
The patent inverts the conventional tuning approach by using a phase shifter to modify the feedback signal phase rather than directly adjusting the resonator frequency. This allows tuning on both sides of the series resonance peak, expanding the effective tuning range while maintaining high accuracy through phase control mechanisms.
Solution Approach 2:
The patent employs a feedback loop where the output signal is phase-shifted and fed back to the input. This feedback mechanism with phase adjustment enables precise control of the oscillation frequency by manipulating the phase relationship between input and output signals, thereby achieving high tuning accuracy across an extended frequency range.
2Manufacturing precision
If the mechanical resonator is designed with specific size, shape, and material to achieve desired resonance frequency, then the inherent resonance frequency can be optimized, but manufacturing tolerances cause deviations from intended values
Solution Approach 1:
The feedback loop with phase shifter compensates for manufacturing tolerances by dynamically adjusting the phase of the feedback signal. This allows the system to maintain accurate resonance frequency operation despite variations in resonator physical dimensions or material properties caused by manufacturing tolerances.
Solution Approach 2:
The patent changes the electrical parameter (phase shift) to compensate for physical parameter variations in the resonator. By adjusting the phase shift amount, the system can compensate for frequency deviations caused by manufacturing tolerances without requiring precise mechanical fabrication.
3Use of energy by moving object
If the oscillator operates at the inherent resonance frequency of the mechanical resonator, then maximum efficiency is achieved, but environmental variations such as temperature and pressure cause frequency shifts
Solution Approach 1:
The phase-shifting feedback loop continuously monitors and adjusts the oscillation frequency to maintain operation at the desired frequency despite environmental variations. This feedback control ensures both high efficiency by keeping the resonator near its optimal operating point and high reliability by compensating for temperature and pressure-induced frequency shifts.
Solution Approach 2:
The patent introduces dynamic phase adjustment capability that allows the system to adapt to changing environmental conditions. The phase shifter can dynamically modify the feedback signal phase in response to frequency drift caused by temperature or pressure changes, maintaining stable operation across varying environmental conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances tuning flexibility and accuracy, enabling the device to operate at desired frequencies despite deviations in the inherent resonance frequency, thereby relaxing manufacturing tolerances and compensating for environmental variations.
Implementation Method 1
shifting a phase of the output signal of the mechanical resonator to produce a phase-shifted signal having a different phase than the phase of the output signal of the mechanical resonator
Implementation Method 2
varying a capacitance value of the LC tuning subcircuit
Implementation Method 3
an LC tuning subcircuit having an input coupled to the drive circuit and an output coupled to the mechanical resonator
Implementation Method 4
The mechanical resonator has an inherent resonance frequency, the value of which depends on factors such as the size, shape, and material of the resonator
Data Source
AI summary
Methods and apparatus for tuning devices having mechanical resonators are described. In one implementation, a mechanical resonator and a phase shifter are configured in a feedback loop, so that the phase shifter shifts the phase of the resonator output signal. The amount of phase shift induced by the phase shifter may be variable. In another implementation, an LC tuning subcircuit is coupled to a mechanical resonator. In some implementations, the LC tuning subcircuit has a variable capacitance. One or more of the apparatus described herein may be implemented as part, or all, of a microelectromechanical system (MEMS).