Parameter-pumped double closed-loop resonant pressure sensor

Abstract

The application provides a kind of double closed loop resonant pressure sensor based on parameter pumping, design sensor technical field, including: single resonator, first drive electrode and second drive electrode are used to apply AC driving signal to single resonator and parameter pumping AC signal to single resonator respectively, the frequency of parameter pumping AC signal is the frequency sum of first order mode and second order mode of single resonator, first detection electrode and second detection electrode are used to detect the resonant frequency and amplitude of single resonator;Closed loop control circuit is used to differentially amplify vibration signal detected by first detection electrode and second detection electrode, obtain second order mode vibration signal, adjust second order mode vibration signal and feedback to first drive electrode, to maintain self-excitation vibration of single resonator;Parameter pumping feedback control loop is used to detect the amplitude of second order mode vibration signal, compare with reference amplitude to obtain error signal, and generate parameter pumping AC signal according to error signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, and more particularly, to a double closed-loop resonant pressure sensor based on parametric pumping. BACKGROUND

[0002] Resonant MEMS pressure sensors have been widely used in semiconductor, industrial control, meteorological monitoring and other fields due to their high precision and high stability. Current researches mainly focus on the basic modal sensing and closed-loop design of resonators, and the decoupling compensation of pressure and temperature and other parameters is realized by integrating multiple resonators or multiple sensors. However, this approach results in a complex sensor structure, increasing the difficulty of design and manufacturing.

[0003] Micro-mechanical resonators generally have an infinite number of modalities. In existing resonant sensor applications, the basic mode is widely used to detect various parameters due to its high signal-to-noise ratio, while the high-order mode is ignored due to its low signal-to-noise ratio. Compared with the basic mode, the high-order mode has a higher response frequency, which often means higher sensing sensitivity and resolution. Using high-order modes for multi-modal sensing is one of the effective ways to break through the detection limit of existing resonant sensors and solve the coupling of multiple measured parameters. In recent years, researchers have paid close attention to the modal coupling and nonlinear vibration characteristics of resonators. Through modal coupling, part of the vibration energy of the basic mode can be transferred to the high-order mode, enhancing the response amplitude of the high-order mode and greatly improving the signal-to-noise ratio of the high-order mode. At the same time, modal coupling means that there may be two or more modal frequencies in the vibration signal. Therefore, using the method of modal coupling can help to realize multi-modal sensing, improve the detection performance of resonant sensors, and solve the problem of multiple cross-coupling physical parameters in the sensor output.

[0004] Parametric pumping provides a controllable and easy-to-implement way to realize inter-modal coupling, which only requires an additional parameter excitation signal of a specific frequency to realize the coupling between complex modes of the resonator, without the need for complex design and error control of the resonator. When the frequency of the parametric pumping signal is the sum of the frequencies of multiple eigenmodes of the resonator, the quality factor and vibration amplitude of the resonator can be amplified. Using this effect, multi-modal pressure sensing of a single resonator can be realized, simplifying the sensor structure, reducing the size of the sensor core, solving the problem of temperature-pressure coupling in the sensor output, and improving the overall performance of the sensor. SUMMARY

[0005] Therefore, the present application provides a double closed-loop resonant pressure sensor based on parametric pumping.

[0006] One aspect of the present application provides a double closed-loop resonant pressure sensor based on parametric pumping, comprising: a single resonator having a first driving electrode, a second driving electrode, a first detecting electrode, a second detecting electrode and a resonant beam; the first driving electrode and the second driving electrode are arranged on one side of the resonant beam; the first detecting electrode and the second detecting electrode are arranged on the other side of the resonant beam; the first driving electrode and the second driving electrode are symmetrically arranged with the first detecting electrode and the second detecting electrode; the first driving electrode is used to apply an alternating driving signal to the single resonator; the second driving electrode is used to apply a parametric pumping alternating signal to the single resonator, the frequency of the parametric pumping alternating signal being the sum of the frequencies of the first-order mode and the second-order mode of the single resonator; the first detecting electrode and the second detecting electrode are used to detect the resonant frequency and amplitude of the single resonator; a closed-loop control circuit having a first input connected to the first detecting electrode and a second input connected to the second detecting electrode, used to differentially amplify the vibration signals detected by the first detecting electrode and the second detecting electrode to obtain a second-order mode vibration signal, and apply the second-order mode vibration signal after phase adjustment and gain control to the first driving electrode to maintain self-excited vibration of the single resonator, the single resonator operating in an anti-symmetric second-order mode; a parametric pumping feedback control loop used to detect the amplitude of the second-order mode vibration signal, compare it with a reference amplitude to obtain an error signal, and generate the parametric pumping alternating signal based on the error signal.

[0007] According to an embodiment of the present application, further comprising: a readout circuit used to read out the resonant frequency of the second-order mode vibration signal and the sum of the frequencies of the first-order mode and the second-order mode of the single resonator; and a decoupling circuit used to decouple two detected physical quantities of pressure and temperature based on the resonant frequency of the second-order mode vibration signal and the sum of the frequencies of the first-order mode and the second-order mode of the single resonator.

[0008] According to an embodiment of the present application, the closed-loop control circuit is a phase-locked loop-based closed-loop control circuit or a self-gain control-based closed-loop control circuit.

[0009] According to an embodiment of the present application, the closed-loop control circuit based on self-gain control comprises: a first current-voltage conversion circuit for converting a first vibration signal of the resonant beam into an electrical signal; a second current-voltage conversion circuit for converting a second vibration signal of the resonant beam into an electrical signal; a differential amplification circuit for differentially amplifying and comparing the first vibration signal and the second vibration signal to improve the signal-to-noise ratio of the second-order modal vibration signal and filter out the first-order modal coupling vibration signal and the parameter-pumped feed signal; a phase-shifting amplification circuit for phase-adjusting the second-order modal vibration signal; and an automatic gain control circuit for gain-controlling based on the phase-adjusted second-order modal vibration signal, and feeding back and adjusting the alternating current driving signal to maintain the self-oscillation of the single resonator.

[0010] According to an embodiment of the present application, the parameter-pumped feedback control loop comprises: an amplitude detection circuit for detecting the amplitude of the second-order modal vibration signal; an amplitude error control circuit for comparing the second-order modal vibration signal with a reference amplitude to generate the error signal; and a voltage-controlled oscillator for generating the parameter-pumped alternating current signal based on the error signal to make the amplitude of the resonator reach the reference amplitude.

[0011] An embodiment of the present application proposes a double-closed-loop resonant pressure sensor based on parameter pumping, the core sensitive structure of which is a single resonator, and the resonator has two driving electrodes and two detection electrodes on both sides. The resonator is applied with an alternating current driving signal and a parameter-pumped alternating current signal through the two driving electrodes, and the resonant frequency and amplitude of the resonator are detected in real time through the detection electrodes. The resonator works in the anti-symmetrical second-order mode through the closed-loop control loop, and the vibration signals detected by the two detection electrodes are differentially converted after current-voltage conversion to improve the signal-to-noise ratio of the second-order modal vibration signal and filter out the common-mode noise and other coupled vibration signals, and the second-order modal frequency f2 of the resonator is output. The parameter-pumped feedback control loop can amplify the second-order modal quality factor and vibration signal of the resonator, and can output the first-order and second-order modal frequencies f1+f2 of the resonator. Since different modes have different sensitivities to pressure / temperature, the two frequency parameters f2 and f1+f2 can decouple the pressure and temperature physical quantities, that is, the single resonator multi-modal sensing is realized, the problem of temperature-pressure coupling in the sensor output is solved, and the sensor structure is further simplified, the sensor core size is reduced, and the overall performance of the sensor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0012] The above and other objects, features and advantages of the present application will become more apparent from the following description of the embodiments of the present application taken with reference to the accompanying drawings, in which:

[0013] Figure 1An electrode configuration diagram of a dual closed-loop resonant pressure sensor based on parametric pumping is shown schematically according to embodiments of the present application.

[0014] Figure 2 An amplification effect of parametric pumping on resonator vibration is shown schematically according to embodiments of the present application.

[0015] Figure 3 A dual closed-loop control diagram of a dual closed-loop resonant pressure sensor based on parametric pumping is shown schematically according to embodiments of the present application. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It is to be understood, however, the drawings are designed for a better understanding, and are not intended to limit the scope of the present application. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one of ordinary skill in the art that one or more embodiments can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring the understanding of this application.

[0017] The terms used herein are merely used to describe specific embodiments, and are not intended to limit the present application. The terms "include" and "have" used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0018] All terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present description, and should not be interpreted in an idealized or overly formal manner.

[0019] In the case of using expressions similar to "at least one of A, B, and C, etc.", it should generally be interpreted to include at least one of each item, unless otherwise defined. For example, "a system having at least one of A, B, and C" should be interpreted to include a system having at least one of A, a system having at least one of B, a system having at least one of C, a system having at least one of A and B, a system having at least one of A and C, a system having at least one of B and C, and / or a system having at least one of A, B, and C, etc.

[0020] The application provides a double closed-loop resonant pressure sensor based on parametric pumping, comprising a single resonator, a closed-loop control circuit and a parametric pumping feedback control loop. The resonator works in a second-order mode through a traditional closed-loop control circuit. When the frequency of the parametric pumping signal is the sum of the first-order mode and the second-order mode frequencies of the resonator, the first-order mode and the second-order mode vibration signals of the resonator are amplified. By using this effect, the signal-to-noise ratio of the second-order mode of the resonator is improved by applying an additional parametric pumping signal, and the closed-loop feedback of the parametric pumping signal is realized through amplitude error control. Based on the double closed-loop system, the second-order mode frequency f2 of the resonator and the parametric pumping frequency (the sum of the first-order mode and the second-order mode frequencies of the resonator f1+f2) can be output, and multi-mode sensing is realized with only one resonator.

[0021] Figure 1 The electrode configuration of the double closed-loop resonant pressure sensor based on parametric pumping according to the embodiment of the application is schematically shown.

[0022] As shown in Figure 1 , the single resonator 1 has a first driving electrode 2-1, a second driving electrode 2-2, a first detection electrode 2-3, a second detection electrode 2-4 and a resonant beam; the first driving electrode 2-1 and the second driving electrode 2-2 are arranged on one side of the resonant beam; the first detection electrode 2-3 and the second detection electrode 2-4 are arranged on the other side of the resonant beam; the first driving electrode 2-1 and the second driving electrode 2-2 are symmetrically arranged with the first detection electrode 2-3 and the second detection electrode 2-4. Among them, the first driving electrode 2-1 is used to apply an alternating driving signal v ac to the single resonator 1; the second driving electrode 2-2 is used to apply a parametric pumping alternating signal v p to the single resonator 1, the frequency fp of the parametric pumping alternating signal v p is the sum of the first-order mode and the second-order mode frequencies of the single resonator 1, i.e. f1+f2; the first detection electrode 2-3 and the second detection electrode 2-4 are used to detect the resonant frequency and amplitude of the single resonator 1, which are converted based on the detected current i out . In addition, the resonator is also powered by a direct current power supply v dc to maintain oscillation.

[0023] Figure 2 The amplification effect of parametric pumping on resonator vibration according to the embodiment of the application is schematically shown.

[0024] As shown in Figure 2 , when a parametric pumping alternating signal v p is applied to the resonator 1 through the second driving electrode 2-2, the frequency fp of which is the sum of the first-order mode and the second-order mode frequencies of the resonator, i.e. f1+f2, the first-order mode and the second-order mode vibration response and quality factor of the resonator are both amplified.

[0025] Utilizing the amplification effect of the AGC loop, embodiments of the present application propose a double closed-loop control method as shown in FIG. 2. Figure 2 Figure 3

[0026] Figure 3 A double closed-loop control diagram of the double closed-loop resonant pressure sensor based on parametric pumping according to embodiments of the present application is schematically shown.

[0027] As shown in FIG. 1, the double closed-loop resonant pressure sensor based on parametric pumping includes a traditional resonator closed-loop control loop (illustrated as an automatic gain control loop) and a parametric pumping feedback control loop. Figure 3

[0028] The closed-loop control circuit can be a phase-locked loop-based closed-loop control circuit or an automatic gain control (AGC)-based closed-loop control circuit. Taking the automatic gain control (AGC)-based closed-loop circuit as an example, the first input end of the closed-loop control circuit is connected to the first detection electrode 2-3, and the second input end is connected to the second detection electrode 2-4, for differentially amplifying the vibration signals detected by the first detection electrode 2-3 and the second detection electrode 2-4 to obtain a second-order modal vibration signal, and applying the second-order modal vibration signal after phase adjustment and gain control to the first drive electrode 2-1 to maintain the self-excited vibration of the single resonator 1, and the single resonator 1 works in the anti-symmetrical second-order mode.

[0029] As shown in FIG. 2, the AGC loop includes a first current-voltage conversion circuit (corresponding to one of the current-voltage conversion links), a second current-voltage conversion circuit (corresponding to the other current-voltage conversion link), a differential amplification circuit (corresponding to the differential amplification link), a phase-shifting amplification circuit (corresponding to the phase-shifting amplification link), and an automatic gain control circuit (corresponding to the automatic gain control link). Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 ​​​​​​​​(Automatic gain control loop). The single resonator 1 operates in antisymmetric second-order mode via a closed-loop automatic gain control circuit. The first detection electrode 2-3 and the second detection electrode 2-4 detect the first and second vibration signals of the resonant beam, respectively. The first and second current-to-voltage conversion circuits convert the first and second vibration signals of the resonant beam into electrical signals, respectively. A differential amplifier circuit amplifies and compares the first and second vibration signals differentially to improve the signal-to-noise ratio of the second-order mode vibration signal and filter out the first-order mode coupled vibration signal and the feedthrough signal from the parameter pump. One path of the differentially amplified second-order mode vibration signal directly outputs the second-order mode resonant frequency f2. The other path, after phase adjustment by a phase-shifting amplifier circuit, undergoes gain control by the automatic gain control circuit and is applied to the first driving electrode 2-1 to maintain the resonator's self-excited vibration.

[0030] The parameter pump feedback control loop is used to detect the amplitude of the second-order modal vibration signal, compare it with the reference amplitude to obtain the error signal, and generate the parameter pump AC signal based on the error signal.

[0031] like Figure 3 As shown, the parameter pump feedback control loop and the automatic gain control (AGC) loop share the current-to-voltage conversion stage and the differential amplification stage, and also include an amplitude detection circuit (corresponding to...). Figure 3 (Signal amplitude detection stage), reference amplitude input, amplitude error control circuit (corresponding to) ​ The system consists of an amplitude error control circuit and a voltage-controlled oscillator (VCO). The amplitude detection circuit detects the amplitude of the second-order modal vibration signal. The amplitude error control circuit compares the second-order modal vibration signal with a reference amplitude to generate an error signal, which, after processing, is output to the VCO. Based on the error signal, the VCO generates an AC signal with a frequency close to the sum of the first and second-order mode frequencies of the resonator, increasing the resonator amplitude to the reference amplitude level. Another output directly yields the sum of the first and second-order mode frequencies of the resonator, f1 + f2.

[0032] When the parameter pump signal is applied to the second driving electrode 2-2, the second-order mode vibration signal, the first-order mode coupled vibration signal, and the parameter pump feedthrough signal in the output signal of the resonator will be coupled together. Through the differential detection of the first detection electrode 2-3 and the second detection electrode 2-4, the first-order mode coupled vibration signal and the parameter pump feedthrough signal can be effectively filtered out, leaving only the second-order mode vibration signal of the resonator, thus ensuring the stability of the dual closed loop.

[0033] Optionally, the amplitude error control link in the parameter pumping feedback control loop can adopt proportional-integral (PI) control, proportional-integral-derivative (PID) control, proportional-integral-derivative (PID) control with feedforward, polynomial fitting control combined with the second-order modal frequency, and nonlinear control, etc., to control the voltage-controlled oscillator to generate a corresponding frequency signal, so that the resonator vibration signal can be amplified.

[0034] Due to the effect of parameter pumping on the improvement of the modal vibration signal quality factor and signal amplification, the stability and resolution of the resonant pressure sensor are improved. In the entire double closed-loop system, the second-order modal resonant frequency f2 of the resonator, the first-order and second-order modal frequencies f1 and f1+f2 of the resonator, and the output are read out, thereby improving the sensitivity of the resonant pressure sensor.

[0035] On this basis, the double closed-loop resonant pressure sensor based on parameter pumping can further include a readout circuit and a decoupling circuit. The readout circuit is configured to read out the resonant frequency f2 of the second-order modal vibration signal and the sum f1+f2 of the first-order and second-order modal frequencies of the single resonator. The decoupling circuit is configured to decouple the resonant frequency f2 of the second-order modal vibration signal and the sum f1+f2 of the first-order and second-order modal frequencies of the single resonator to obtain two detected physical quantities, i.e., pressure and temperature, thereby realizing single-resonator multi-modal sensing. The sensor design solves the problem of temperature-pressure coupling in the sensor output and helps to further simplify the sensor structure and reduce the size of the sensor core.

[0036] In summary, the double closed-loop resonant pressure sensor based on parameter pumping provided in the present application has two closed loops: a traditional resonator closed-loop control loop and a parameter pumping feedback control loop. The double closed-loop system can read out the second-order modal resonant frequency f2 of the resonator, the sum f1+f2 of the first-order and second-order modal frequencies of the resonator, thereby improving the sensitivity of the sensor and realizing single-resonator multi-modal sensing, solving the problem of temperature-pressure coupling in the sensor output, and helping to further simplify the sensor structure and reduce the size of the sensor core. Through the parameter pumping feedback loop, due to the effect of parameter pumping on the improvement of the modal vibration signal quality factor and signal amplification, the stability and resolution of the resonant pressure sensor are improved. In addition, through the second-order modal anti-symmetry characteristic and differential detection of the double detection electrodes, the first-order modal coupled vibration signal and the parameter pumping feed signal can be effectively filtered out, leaving only the second-order modal vibration signal of the resonator, thereby ensuring the stability of the double closed loop. The double closed-loop circuit has a simple structure and can be realized by ordinary analog circuits or digital circuits.

[0037] The embodiments of the application have been described. However, these embodiments are merely for illustration and are not intended to limit the scope of the application. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Various alternatives and modifications to the embodiments described herein will be apparent to those skilled in the art in view of the foregoing description. Such alternatives and modifications are intended to fall within the scope of the application.

Claims

1. A dual closed-loop resonant pressure sensor based on parametric pumping, characterized in that, The application relates to a single resonator and a closed-loop control circuit thereof. The single resonator comprises a first driving electrode, a second driving electrode, a first detecting electrode, a second detecting electrode and a resonant beam; the first driving electrode and the second driving electrode are arranged on one side of the resonant beam; the first detecting electrode and the second detecting electrode are arranged on the other side of the resonant beam; the first driving electrode and the second driving electrode are symmetrically arranged with the first detecting electrode and the second detecting electrode. The first driving electrode is used for applying an alternating-current driving signal to the single resonator; the second driving electrode is used for applying a parameter-pumped alternating-current signal to the single resonator, the frequency of the parameter-pumped alternating-current signal being the sum of the frequencies of the first-order mode and the second-order mode of the single resonator; the first detecting electrode and the second detecting electrode are used for detecting the resonant frequency and the amplitude of the single resonator. A closed-loop control circuit has a first input end connected to the first detecting electrode and a second input end connected to the second detecting electrode, is used for differentially amplifying the vibration signals detected by the first detecting electrode and the second detecting electrode to obtain a second-order mode vibration signal, and is used for applying the second-order mode vibration signal after phase adjustment and gain control to the first driving electrode to maintain self-excitation vibration of the single resonator, the single resonator working in an anti-symmetrical second-order mode. A parameter-pumped feedback control loop is used for detecting the amplitude of the second-order mode vibration signal, comparing the amplitude with a reference amplitude to obtain an error signal, and generating the parameter-pumped alternating-current signal according to the error signal.

2. The parametric-pump-based dual closed-loop resonant pressure sensor of claim 1, wherein, The application further relates to a readout circuit, a decoupling circuit and a parameter-pumped feedback control loop. The readout circuit is used for reading out the resonant frequency of the second-order mode vibration signal and the sum of the frequencies of the first-order mode and the second-order mode of the single resonator. The decoupling circuit is used for decoupling to obtain two detected physical quantities of pressure and temperature based on the resonant frequency of the second-order mode vibration signal and the sum of the frequencies of the first-order mode and the second-order mode of the single resonator.

3. The parametric-pump-based dual closed-loop resonant pressure sensor of claim 1, wherein, The closed-loop control circuit is a phase-locked loop-based closed-loop control circuit or a self-gain control-based closed-loop control circuit.

4. The parametric-pump-based dual closed-loop resonant pressure sensor of claim 3, wherein, The self-gain control-based closed-loop control circuit comprises: A first current-voltage conversion circuit is used for converting a first vibration signal of the resonant beam into an electric signal. A second current-voltage conversion circuit is used for converting a second vibration signal of the resonant beam into an electric signal. A differential amplification circuit is used for differentially amplifying and comparing the first vibration signal and the second vibration signal to improve the signal-to-noise ratio of the second-order mode vibration signal and filter out a first-order mode coupling vibration signal and a parameter-pumped feed signal. A phase-shifting amplification circuit is used for phase-adjusting the second-order mode vibration signal. An automatic gain control circuit is used for gain-controlling the second-order mode vibration signal after phase adjustment, and feedback adjusting the alternating-current driving signal to maintain self-excitation vibration of the single resonator.

5. The parametric-pump-based dual closed-loop resonant pressure sensor of claim 1, wherein, The parameter-pumped feedback control loop comprises: An amplitude detection circuit is used for detecting the amplitude of the second-order mode vibration signal. An amplitude error control circuit is used for comparing the second-order mode vibration signal with the reference amplitude to generate the error signal. a voltage controlled oscillator for generating the parametric pump alternating current signal based on the error signal to bring the amplitude of the resonator to the reference amplitude.

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