Tuning fork matching circuit

A quartz tuning fork and matching circuit technology, applied in the field of circuits, can solve the problems of the asymmetry of the resonance frequency and the resonance frequency shift, the mismatch of the quartz tuning fork circuit, the reduction of the resonance amplitude of the tuning fork and the quality factor of the vibration, etc. Symmetry and resonant frequency shift, eliminating the effect of mismatch

Inactive Publication Date: 2013-10-09
SUZHOU INST OF NANO TECH & NANO BIONICS CHINESE ACEDEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in some special use environments, such as when the quartz is exposed to the air, the base is fixed, the base is worn, and the wall of the tuning fork is stuck with foreign objects, the structure of the quartz tuning fork is changed to a certain extent, and the corresponding mass m Changes have caused its resonance characteristic parameters R, L, and C to change relative to the previous ones, and the parasitic capacitance C 0 is also greatly increased, causing mismatch in the quartz tuning fork circuit, figure 2 The frequency characteristic curves before and after the tuning fork mismatch
When the quartz tuning fork resonates, the current through the LRC branch is in phase with the voltage, and the parasitic capacitance C 0 The current has a 90° phase shift, which leads to the asymmetry of the resonant frequency and the shift of the resonant frequency, thereby greatly reducing the resonance amplitude and vibration quality factor of the tuning fork

Method used

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Embodiment 1

[0042] In this embodiment, the compensation circuit mainly includes a variable capacitor, and the value of the variable capacitor is the compensation capacitor C c , the variable capacitor is directly connected in parallel to both ends of the quartz tuning fork circuit. By adjusting the value of the variable capacitor, it is compatible with the parasitic capacitance C generated by the quartz tuning fork circuit 0 When equal, a match is achieved. Generally speaking, the variable capacitors currently available for purchase are compared to the parasitic capacitance C generated by the quartz tuning fork circuit. 0 Much larger and more difficult to adjust to match. Multiple variable capacitors can be connected in series (C c1 、…C cn ) way to achieve a smaller compensation capacitance C c, enabling it to interact with the parasitic capacitance C 0 match, such as Figure 6 shown. Part of the variable capacitors connected in series can be used for coarse adjustment, and part o...

Embodiment 2

[0044] Due to the parasitic capacitance C 0 Much larger and more difficult to adjust to match. The parasitic capacitance C of the quartz tuning fork 0 It can change with different connections and the influence of various external factors, so it can be considered by increasing the parasitic capacitance C 0 In order to match the parasitic capacitance with the compensation capacitance. Therefore, in this embodiment, by connecting a compensation capacitor C in parallel with the two ends of the tuning fork c similar capacitance C s , capacitance C s have the same input signal as a quartz tuning fork circuit, such as Figure 7 As shown, the parasitic capacitance generated by the quartz tuning fork circuit at this time is C' 0 =C 0 +C s . That is, by increasing the parasitic capacitance, the compensation circuit can accurately generate a compensation capacitance C that matches the parasitic capacitance c .

[0045] It should be noted that the compensation capacitor C descr...

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Abstract

The invention provides a tuning fork matching circuit. The tuning fork matching circuit comprises a tuning fork circuit, a compensating circuit and a transformer, wherein the compensating circuit is connected with the tuning fork circuit, a compensating capacitor is produced by the compensating circuit, the value of the compensating capacitor is close to the value of a parasitic capacitor produced by the tuning fork circuit, a difference between the value of the compensating capacitor and the value of the parasitic capacitor is within the range of + / -5% of the value of the parasitic capacitor, an input signal is added to the input end of the transformer, the transformer is provided with two output ends, and the output ends provide input signals with a phase difference of pi for the tuning fork circuit and the compensating circuit respectively. The tuning fork matching circuit can solve the problem of mismatch of the tuning fork circuit caused by the parasitic capacitor C0, and effectively overcomes the defects of asymmetry and offset of resonant frequency of a tuning fork.

Description

technical field [0001] The invention relates to a circuit, in particular to a matching circuit of a quartz tuning fork. Background technique [0002] Quartz tuning fork (TuningForks, TF) is a resonant element made of the piezoelectric effect of quartz crystal. Due to the advantages of wide sources of quartz crystal, stable chemical properties, high elastic coefficient, small thermal expansion coefficient, strong frequency stability, high quality factor (Q value) and self-oscillation, the system has high sensitivity and is a clock circuit. It is the most important part of the instrument and can be widely used in atomic force microscope (AtomicForce Microscope, AFM) and quartz crystal microbalance (QuartzCrystalMicrobalance, QCM). Applying AC voltage to the two electrodes of the quartz tuning fork can excite its vibration. By detecting the current value flowing through the quartz tuning fork, the vibration state of the arms of the quartz tuning fork can be detected. When the ...

Claims

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Application Information

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IPC IPC(8): H03H9/215
Inventor苏丽娜吕利秦华顾晓峰
OwnerSUZHOU INST OF NANO TECH & NANO BIONICS CHINESE ACEDEMY OF SCI