Acoustic Wave Resonator Circuit With Active Shunt Capacitance Cancellation
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Solution Overview
Problem
Acoustic wave systems face challenges in precisely tracking mechanical and electrical changes due to non-zero electrical contributions from resonator shunt capacitance, requiring advanced methods to avoid complex signal deconvolution schemes.
Innovation Solution
An active shunt capacitance cancelling oscillator circuit is employed, using an inactive resonator with similar electrical properties as a 'dummy' capacitance to cancel out shunt capacitance associated with the active resonator, providing an output signal proportional to oscillation amplitude and resonator loss, allowing for accurate tracking of resonant frequency and acoustic contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional acoustic wave systems are used without capacitance cancellation, then the system structure is simpler, but impedance distortion and phase shift anomalies occur due to non-zero shunt capacitance
Solution Approach 1:
An inactive resonator is introduced as an intermediary component to provide a dummy capacitance that matches the shunt capacitance of the active resonator. This dummy capacitance is used in the oscillator circuit to cancel out the harmful electrical contributions from the active resonator's shunt capacitance, thereby improving measurement accuracy without requiring complex signal processing
Solution Approach 2:
An inactive resonator is created as a copy of the active resonator structure, but without the acoustic wave propagation capability. This copy serves as a reference to extract and provide the dummy capacitance value, allowing the system to compensate for the active resonator's shunt capacitance effects through capacitance cancellation in the oscillator circuit
2Measurement precision
If signal deconvolution schemes are used to extract resonator parameters, then measurement precision can be improved, but the system becomes more complex and difficult to operate
Solution Approach 1:
The inactive resonator provides the dummy capacitance value in advance, before the actual measurement process begins. This pre-established reference capacitance is embedded in the oscillator circuit, allowing the system to directly track resonant frequency without requiring post-measurement signal deconvolution or complex data processing
Solution Approach 2:
The oscillator circuit automatically compensates for shunt capacitance effects through the dummy capacitance from the inactive resonator. The system self-corrects for electrical contributions without requiring external signal processing or complex algorithms, making the operation simpler while maintaining high measurement precision
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 solution enables more precise monitoring of resonator parameters and reduces impedance distortion and phase shift anomalies, improving the accuracy of acoustic wave sensor systems by effectively removing non-zero shunt capacitance contributions.
Implementation Method 1
an electrode region disposed on the top surface of the first piezoelectric substrate, where the electrode region is configured to launch a shear horizontal surface acoustic wave
Implementation Method 2
the electrode region is configured to launch a shear horizontal surface acoustic wave and to detect the acoustic wave transmitted through the substrate
Implementation Method 3
the current mirror is configured to provide a current component controlled by a capacitance of the inactive resonator, thereby effectively cancelling out a shunt capacitance associated with the active resonator
Data Source
AI summary
The present invention relates to systems including an acoustic wave resonator and an active shunt capacitance cancelling oscillator circuit. Such systems can be used in biosensing methods, while avoiding impedance distortion and phase shift anomalies.