Resonance circuit of MEMS gyroscope and MEMS gyroscope

Abstract

The invention is suitable for the technical field of MEMS gyroscopes, and provides a resonance circuit of an MEMS gyroscope and the MEMS gyroscope, the resonance circuit comprises a sensitive structure chip, a capacitance voltage conversion circuit, a rectification circuit, an error comparison circuit, a PID circuit, a low-pass filter circuit and a stress application circuit; the sensitive structure chip is used for detecting the capacitance value of the gyroscope and controlling the resonance of the gyroscope; the capacitance detection signal output end of the sensitive structure chip is sequentially connected with a capacitance-voltage conversion circuit, a rectification circuit, an error comparison circuit, a PID circuit, a low-pass filter circuit and a stress application circuit; and the stress application circuit is also connected with a resonance control signal input end of the sensitive structure chip. The MEMS gyroscope can solve the problems that in the prior art, an MEMS gyroscope is large in resonance circuit area, complex in design and high in power consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of MEMS gyroscopes, and in particular relates to a resonant circuit of a MEMS gyroscope and a MEMS gyroscope. Background Art

[0002] MEMS (Micro-Electro-Mechanical System) gyroscope is an angular velocity sensor. It is widely used in defense, industry, automobile and consumer fields due to its good performance, small size, low power consumption and easy batch manufacturing.

[0003] When the MEMS gyroscope is working, the mass block needs to be in a resonant state. When there is an external angular velocity input, a Coriolis force will be generated. The Coriolis force acts on the mass block to produce displacement, which in turn causes a change in the detection capacitor. The subsequent processing circuit can output a voltage or digital value proportional to the input angular velocity by detecting the changed capacitance. Therefore, designing a high-quality resonant circuit is the key to a high-performance gyroscope. In related technologies, the resonant circuit of the MEMS gyroscope has the disadvantages of large area, complex design and high power consumption. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a resonant circuit of a MEMS gyroscope and a MEMS gyroscope to solve the problems of a large resonant circuit area, complex design and high power consumption of a MEMS gyroscope in the prior art.

[0005] A first aspect of an embodiment of the present invention provides a resonant circuit of a MEMS gyroscope, comprising: a sensitive structure chip, a capacitor-voltage conversion circuit, a rectifier circuit, an error comparison circuit, a PID circuit, a low-pass filter circuit, and a force adding circuit; The sensitive structure chip is used to detect the capacitance of the gyroscope and control the resonance of the gyroscope; The capacitance detection signal output end of the sensitive structure chip is connected to the capacitance-voltage conversion circuit, the rectification circuit, the error comparison circuit, the PID circuit, the low-pass filter circuit and the force adding circuit in sequence; the force adding circuit is also connected to the resonance control signal input end of the sensitive structure chip.

[0006] In combination with the first aspect, in a possible implementation of the first aspect, the sensitive structure chip includes: a detection capacitor pair and a force capacitor pair; The detection capacitor pair is used to detect the capacitance of the gyroscope, and the detection capacitor pair is connected to the capacitance-voltage conversion circuit to output a capacitance detection signal; The forcing capacitor pair is used to control the resonance of the gyroscope, and the forcing capacitor pair is connected to the forcing circuit to input a resonance control signal.

[0007] In combination with the first aspect, in a possible implementation manner of the first aspect, the capacitance detection signal is a differential signal including two capacitances; The capacitor voltage conversion circuit is used to convert V drv_c2v =-V ref *(C md_1 -C md_2 ) / C f The input capacitance detection signal is converted into a voltage signal and output; where V drv_c2v is the voltage signal; C md_1 and C md_2 are two capacitance values ​​of the capacitance detection signal; V ref is the signal voltage value added to the middle mass block of the gyroscope; C f is the integral capacitor of the capacitor-to-voltage conversion circuit.

[0008] In combination with the first aspect, in a possible implementation manner of the first aspect, the rectifier circuit is used to perform full-wave rectification on the input voltage signal and output a DC signal.

[0009] In combination with the first aspect, in a possible implementation manner of the first aspect, the error comparison circuit is used to perform a proportional difference between the vibration amplitude of the input DC signal and the target amplitude, and output an error signal.

[0010] In combination with the first aspect, in a possible implementation of the first aspect, the PID circuit includes: an integrator, a differentiator, and a gain summing circuit; The integrator is connected to the error comparison circuit, and is used to integrate the input error signal, filter out the high-frequency signal, and output a low-frequency signal; The low-frequency signal is directly used as the I channel input signal of PID, and is differentiated by the differentiator, and the differentiation result is used as the P channel input signal of PID; The gain summing circuit is used to perform gain summing on the I-channel input signal and the P-channel input signal, and output a control signal.

[0011] In combination with the first aspect, in a possible implementation manner of the first aspect, the low-pass filter circuit is used to filter out high-frequency noise and interference in the input control signal.

[0012] In combination with the first aspect, in a possible implementation manner of the first aspect, the force adding circuit is used to generate a resonance control signal according to an input control signal.

[0013] In combination with the first aspect, in a possible implementation manner of the first aspect, the rectifier circuit and the booster circuit both include: a first controllable switch, a second controllable switch, a third controllable switch, and a fourth controllable switch; The input ends of the first controllable switch and the third controllable switch are connected to serve as the first input end of the target circuit; the second controllable switch and the input end of the fourth controllable switch are connected to serve as the second input end of the target circuit; the output ends of the first controllable switch and the second controllable switch are connected to serve as the first output end of the target circuit; the output ends of the third controllable switch and the fourth controllable switch are connected to serve as the second output end of the target circuit; wherein the target circuit is the rectifier circuit or the booster circuit; The conduction states of the first controllable switch, the second controllable switch, the third controllable switch and the fourth controllable switch are controlled by a Ctrl signal; When the Ctrl signal is at a high level, the first controllable switch and the fourth controllable switch are turned on, and when the Ctrl signal is at a low level, the second controllable switch and the third controllable switch are turned on.

[0014] A second aspect of an embodiment of the present invention provides a MEMS gyroscope, comprising a resonant circuit of the MEMS gyroscope according to the first aspect or any one of the implementations of the first aspect.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The embodiment of the present invention proposes a resonant circuit of a MEMS gyroscope, which detects the capacitance of the gyroscope through a sensitive structure chip to obtain a capacitance detection signal; the capacitor voltage conversion circuit converts the changing capacitance into a voltage signal; the rectifier circuit performs full-wave rectification on the voltage signal of the sine wave to obtain a DC signal; the error comparison circuit compares the DC signal with the target value to obtain the error signal; the PID circuit implements PID operation on the error signal; the force adding circuit adds a resonant control signal to the sensitive structure chip according to the PID operation result, and dynamically corrects the driving voltage of the sensitive structure chip. The resonant circuit of the embodiment of the present invention is implemented by a pure analog circuit, and integrates the functions of rectification demodulation, error comparison, PID and feedback force adding, with simple circuit structure and control, advanced performance, low power consumption, and high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1 Schematic diagram of a resonant circuit of a MEMS gyroscope provided in an embodiment of the present invention Figure 1 ; Figure 2Schematic diagram of a resonant circuit of a MEMS gyroscope provided in an embodiment of the present invention Figure 2 ; Figure 3 is a signal schematic diagram provided by an embodiment of the present invention; Figure 4 is a schematic diagram of a rectifier circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0019] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0020] The MEMS gyroscope mainly includes a cantilever beam structure, a sensitive structure chip and a processing circuit. The cantilever beam structure is the core component of the MEMS gyroscope. It consists of a tiny cantilever beam. The vibration of the cantilever beam will be affected by the external torque, thereby realizing the measurement of the gyroscope. The sensitive structure chip is a capacitive principle, which is used to detect the displacement change of the cantilever beam vibration and realize the measurement of the gyroscope by measuring the change of capacitance. The processing circuit is used to amplify, filter and digitize the signals collected by the sensor, and finally output the measurement results of the gyroscope.

[0021] Designing a high-quality resonant circuit is the basis of a high-performance gyroscope. The resonant circuit is a micromechanical circuit loop, and the mechanical part and the circuit form a positive feedback. When the circuit is driven, the mechanical part starts to vibrate due to its own high quality factor; during the vibration process, the circuit part detects the vibration amplitude in real time and performs negative feedback on the vibration amplitude, ultimately achieving a stable amplitude oscillation of the resonant circuit.

[0022] Currently, common gyroscope resonant circuits are often large in area, complex in design, and have high power consumption. For example, the resonant circuits of existing MEMS gyroscopes can be divided into two categories: PID-based digital-to-analog loops and P-based analog control loops. The PID-based digital-to-analog loop consists of an analog part and a digital part. The analog part implements capacitor-voltage conversion, analog-to-digital conversion, and voltage boost, and the digital part often uses a multiplier to implement rectification and demodulation, and logic to implement PID and other functions. The P-based analog control loop is implemented using a pure analog circuit, and the implementation methods are diverse, but most of them are relatively complex.

[0023] To this end, an embodiment of the present invention proposes a resonant circuit of a MEMS gyroscope, which is implemented using a pure analog circuit and integrates functions such as rectification and demodulation, error comparison, PID and feedback force. The circuit architecture is novel, the performance is advanced, the power consumption is low, and it is highly innovative.

[0024] Please refer to the following Figure 1 and Figure 2 As shown, the resonant circuit of the MEMS gyroscope proposed in the embodiment of the present invention is described.

[0025] First, Figure 1 As shown, the resonance circuit of the MEMS gyroscope includes: a sensitive structure chip 11, a capacitance voltage conversion circuit 12, a rectifier circuit 13, an error comparison circuit 14, a PID circuit 15, a low-pass filter circuit 16 and a force adding circuit 17. Among them, the capacitance detection signal output end of the sensitive structure chip 11 is connected to the capacitance voltage conversion circuit 12, the rectifier circuit 13, the error comparison circuit 14, the PID circuit 15, the low-pass filter circuit 16 and the force adding circuit 17 in sequence; the force adding circuit 17 is also connected to the resonance control signal input end of the sensitive structure chip 11.

[0026] The sensitive structure chip 11 is used to detect the capacitance of the gyroscope and control the resonance of the gyroscope. The sensitive structure chip is a capacitive principle, and is processed by a vacuum process, and its quality factor is relatively high (several thousand to tens of thousands). It consists of two pairs of capacitors, one pair of capacitors is used for capacitance detection, and the other pair of capacitors is used for force driving. When working, a voltage is applied to its driving pin, and the electrostatic force generated by the voltage difference will drive the middle mass block to vibrate, thereby causing a change in the detection capacitance.

[0027] The capacitance-to-voltage conversion circuit 12 can convert the changing capacitance into voltage. Since the mass block is in a resonant state, the output voltage of the capacitance-to-voltage conversion circuit 12 is a sine wave.

[0028] The rectifier circuit 13 can perform full-wave rectification on the sine wave, invert the voltage amplitude in the negative half cycle, and keep the voltage amplitude unchanged in the positive half cycle. By rectifying, the AC signal is converted into a DC signal, and the DC information contained is proportional to the amplitude of the sine wave.

[0029] The error comparison circuit 14 compares the DC signal with the voltage target value to obtain the difference.

[0030] The PID circuit 15 implements a PID operation on the error signal.

[0031] The low-pass filter circuit 16 filters out high-frequency noise and interference of the output signal of the PID circuit 15 to obtain a low-frequency control signal with higher quality.

[0032] The output of the low-pass filter 16 applies a driving voltage to the sensitive structure chip 11 through the force-adding circuit 17 to control and adjust its vibration.

[0033] The entire resonant circuit works in a positive feedback state, and resonance is achieved through a micromechanical circuit system; at the same time, the mechanical vibration amplitude of the sensitive structure chip 11 is detected, and the error between the vibration amplitude and the target value is compared in real time. By performing PID calculation on the error, the driving voltage of the sensitive structure chip 11 is dynamically corrected to achieve negative feedback of the mechanical vibration amplitude, and finally achieve steady-amplitude oscillation.

[0034] The resonant circuit of the MEMS gyroscope proposed in the embodiment of the present invention detects the capacitance of the gyroscope through the sensitive structure chip to obtain a capacitance detection signal; the capacitor voltage conversion circuit converts the changing capacitance into a voltage signal; the rectifier circuit performs full-wave rectification on the sine wave voltage signal to obtain a DC signal; the error comparison circuit compares the DC signal with the target value to obtain the error signal; the PID circuit implements the PID operation on the error signal; the force adding circuit adds a resonant control signal to the sensitive structure chip according to the PID operation result to dynamically correct the driving voltage of the sensitive structure chip. The resonant circuit of the embodiment of the present invention is implemented by a pure analog circuit, and integrates the functions of rectification demodulation, error comparison, PID and feedback force adding, with simple circuit structure and control, advanced performance, low power consumption, and high application value.

[0035] Figure 2 is a more detailed schematic diagram of a resonant circuit. In the following embodiments, Figure 2 , the sensitive structure chip 11, the capacitor-voltage conversion circuit 12, the rectifier circuit 13, the error comparison circuit 14, the PID circuit 15, the low-pass filter circuit 16 and the boost circuit 17 are introduced.

[0036] like Figure 2 As shown, one side of the sensitive structure chip 11 (MEMS) is connected to the mass block of the gyroscope. The sensitive structure chip 11 includes: a detection capacitor pair (C md_1, C md_2 ) and the boost capacitor pair (C ma_1, C ma_2 ). The detection capacitor pair is used to detect the capacitance of the gyroscope, and the detection capacitor pair is connected to the capacitance-voltage conversion circuit to output a capacitance detection signal. The capacitance detection signal here is a differential signal including two capacitances.

[0037] The capacitor voltage conversion circuit is composed of a differential amplifier, a reset switch, etc. The differential signal is input to the differential amplifier, and the differential amplifier converts the capacitor voltage into a capacitor according to V drv_c2v =-V ref *(C md_1 -C md_2 ) / C fThe input capacitance detection signal is converted into a voltage signal and output; where V drv_c2v is the voltage signal; C md_1 and C md_2 are the two capacitance values ​​of the capacitance detection signal; V ref is the signal voltage value added to the middle mass block of the gyroscope; C f It is the integrating capacitor of the capacitor-to-voltage conversion circuit.

[0038] The voltage signal is a sine wave, such as Figure 3 drv_c2v_p-drv_c2v_n in.

[0039] The rectifier circuit performs full-wave rectification on the voltage signal output by the capacitor voltage conversion circuit. Figure 4 As shown, it includes: a first controllable switch K1, a second controllable switch K2, a third controllable switch K3 and a fourth controllable switch K4; the input ends of the first controllable switch K1 and the third controllable switch K3 are connected as the first input end of the rectifier circuit; the input ends of the second controllable switch K2 and the fourth controllable switch K4 are connected as the second input end of the rectifier circuit; the output ends of the first controllable switch K1 and the second controllable switch K2 are connected as the first output end of the rectifier circuit; the output ends of the third controllable switch K3 and the fourth controllable switch K4 are connected as the second output end of the rectifier circuit. The conduction state of the first controllable switch K1, the second controllable switch K2, the third controllable switch K3 and the fourth controllable switch K4 is controlled by the Ctrl signal; when the Ctrl signal is at a high level, the first controllable switch K1 and the fourth controllable switch K4 are turned on, and when the Ctrl signal is at a low level, the second controllable switch K2 and the third controllable switch K3 are turned on. Thus. When the control signal Ctrl is at a high level, the output = input; when the control signal Ctrl is at a low level, the output = - input. The output signal of the rectifier switch is an amplitude-dependent DC signal plus a harmonic signal of twice the driving frequency. The Ctrl signal of the rectifier switch is as follows: Figure 3 drv_pos in , which has the same phase as the resonant signal.

[0040] The error comparison circuit realizes the proportional difference between the voltage signal and the target voltage (that is, the proportional difference between the vibration amplitude and the target amplitude) through the resistor and outputs an error signal.

[0041] The PID circuit includes: an integrator, a differentiator and a gain summing circuit. The integrator is connected to the error comparison circuit, and is used to integrate the input error signal, filter out the high-frequency signal, and output a low-frequency signal; the low-frequency signal is directly used as the I channel input signal of the PID, and is differentiated by the differentiator, and the differential result is used as the P channel input signal of the PID; the gain summing circuit is used to sum the gains of the I channel input signal and the P channel input signal, to achieve the desired PID operation and output the control signal.

[0042] The low-pass filter circuit is used to filter out high-frequency noise and interference in the input control signal to obtain a higher-quality low-frequency control signal.

[0043] The output of the low-pass filter applies the resonant control signal drv_act_p / drv_act_n (driving voltage) to the force capacitor pair of the sensitive structure chip through the force circuit. Because the MEMS sensitive structure is a high-Q second-order resonant system, the phase shift of the transfer function at the resonant frequency is -90 degrees, and the phase of drv_vel relative to the resonant waveform is 90 degrees. The sum of the two is 0 degrees. The entire micromechanical circuit loop realizes positive feedback, and the sensitive structure is in a resonant state. The structure of the force circuit can be referred to Figure 4 The control signal of the boost circuit is drv_vel, and its phase relationship is as follows: Figure 3 As shown, the output of the boost circuit is a square wave signal, the phase of the square wave signal is the same as drv_vel, and the amplitude of the square wave signal is controlled by PID.

[0044] An embodiment of the present invention further provides a MEMS gyroscope, comprising the resonant circuit of the MEMS gyroscope in the above embodiment.

[0045] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A resonant circuit of a MEMS gyroscope, characterized in that: include: Sensitive structure chip, capacitor voltage conversion circuit, rectifier circuit, error comparison circuit, PID circuit, low-pass filter circuit and boost circuit; The sensitive structure chip is used to detect the capacitance of the gyroscope and control the resonance of the gyroscope; The capacitance detection signal output end of the sensitive structure chip is connected to the capacitance-voltage conversion circuit, the rectification circuit, the error comparison circuit, the PID circuit, the low-pass filter circuit and the force adding circuit in sequence; the force adding circuit is also connected to the resonance control signal input end of the sensitive structure chip.

2. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The sensitive structure chip includes: a detection capacitor pair and a force capacitor pair; The detection capacitor pair is used to detect the capacitance of the gyroscope, and the detection capacitor pair is connected to the capacitance-voltage conversion circuit to output a capacitance detection signal; The forcing capacitor pair is used to control the resonance of the gyroscope, and the forcing capacitor pair is connected to the forcing circuit to input a resonance control signal.

3. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The capacitance detection signal is a differential signal including two capacitance values; The capacitor voltage conversion circuit is used to convert V drv_c2v =-V ref *(C md_1 -C md_2 ) / C f Convert the input capacitance detection signal into a voltage signal and output it; Among them, V drv_c2v is the voltage signal; C md_1 and C md_2 are two capacitance values ​​of the capacitance detection signal; V ref is the signal voltage value added to the middle mass block of the gyroscope; C f is the integral capacitor of the capacitor-to-voltage conversion circuit.

4. The resonant circuit of the MEMS gyroscope according to claim 1, characterized in that: The rectifier circuit is used to perform full-wave rectification on the input voltage signal and output a DC signal.

5. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The error comparison circuit is used to calculate the difference between the vibration amplitude of the input DC signal and the target amplitude, and output an error signal.

6. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The PID circuit comprises: an integrator, a differentiator and a gain summing circuit; The integrator is connected to the error comparison circuit, and is used to integrate the input error signal, filter out the high-frequency signal, and output a low-frequency signal; The low-frequency signal is directly used as the I channel input signal of PID, and is differentiated by the differentiator, and the differentiation result is used as the P channel input signal of PID; The gain summing circuit is used to perform gain summing on the I-channel input signal and the P-channel input signal, and output a control signal.

7. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The low-pass filter circuit is used to filter out high-frequency noise and interference in the input control signal.

8. The resonant circuit of the MEMS gyroscope as claimed in claim 1, characterized in that: The boosting circuit is used to generate a resonance control signal according to an input control signal.

9. The resonant circuit of a MEMS gyroscope according to claim 4 or 8, characterized in that: The rectifier circuit and the booster circuit both include: a first controllable switch, a second controllable switch, a third controllable switch and a fourth controllable switch; The input ends of the first controllable switch and the third controllable switch are connected to serve as the first input end of the target circuit; the second controllable switch and the input end of the fourth controllable switch are connected to serve as the second input end of the target circuit; the output ends of the first controllable switch and the second controllable switch are connected to serve as the first output end of the target circuit; the output ends of the third controllable switch and the fourth controllable switch are connected to serve as the second output end of the target circuit; wherein the target circuit is the rectifier circuit or the booster circuit; The conduction states of the first controllable switch, the second controllable switch, the third controllable switch and the fourth controllable switch are controlled by a Ctrl signal; When the Ctrl signal is at a high level, the first controllable switch and the fourth controllable switch are turned on, and when the Ctrl signal is at a low level, the second controllable switch and the third controllable switch are turned on.

10. A MEMS gyroscope, characterized in that: A resonant circuit comprising a MEMS gyroscope as claimed in any one of claims 1 to 9.

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