Calibration apparatus and calibration method for non-linear mismatch of differential mems resonant accelerometer

Abstract

A calibration apparatus and method for nonlinear mismatch in a differential MEMS resonant accelerometer are disclosed. The apparatus includes a differential MEMS resonant accelerometer, a calibration control circuit, and a test signal generator. The differential MEMS resonant accelerometer has identical first and second channels. This invention suppresses flicker noise introduced by nonlinear stiffness mismatch between the two channels of the differential MEMS resonant accelerometer due to manufacturing defects, thereby further improving the performance of the differential MEMS resonant accelerometer. This invention suppresses flicker noise introduced by nonlinear stiffness mismatch without changing the mechanical architecture of the differential MEMS resonant accelerometer and maintains its high bandwidth and high signal-to-noise ratio characteristics.

Description

Technical Field

[0001] This invention relates to differential MEMS resonant accelerometers, and more particularly to a calibration device and method for nonlinear mismatch in differential MEMS resonant accelerometers. Background Technology

[0002] Differential MEMS resonant accelerometers, due to their small size, low cost, low power consumption, and ease of integration, are well-suited to the trend of high-precision, miniaturized acceleration measurement circuits and are widely used in acceleration measurement scenarios such as mobile communications, aerospace, medical devices, and gaming. However, the extremely small microstructures in MEMS inertial sensors are susceptible to mechanical or electronic noise. This limits the accuracy and stability of differential MEMS resonant accelerometers. A key factor in improving the performance of differential MEMS resonant accelerometers in high-precision applications requiring long-term stability is to limit the low-frequency noise in the measured acceleration to a low level. The low-frequency noise that reduces the performance of silicon oscillating accelerometers (SOAs) mainly includes temperature-dependent offset and flicker noise. While MEMS sensor design and temperature compensation methods can effectively reduce temperature-dependent offset, flicker noise remains a challenging problem in improving the ultimate long-term stability of silicon oscillating accelerometers (SOAs).

[0003] One existing technology is chopper stabilization, which suppresses incoherent noise in automatic amplitude control circuits (see reference [1], X. Wang et al., "A 0.4 μg Bias Instability and 1.2 μg / √Hz Noise FloorMEMS Silicon Oscillating Accelerometer With CMOS Readout Circuit," IEEE Journal of Solid-State Circuits, vol.52, no.2, pp.472-482, Feb.2017). Figure 1 The working principle of chopper stabilization technology for suppressing incoherent noise in automatic amplitude control circuits: This technology divides the influence of flicker noise in the automatic amplitude control circuit of a differential MEMS resonant accelerometer into additive and multiplicative components, and then uses chopper stabilization technology and a tailless current source error amplifier to suppress flicker noise. The drawback of this existing technology is that it only addresses flicker noise introduced by amplitude mismatch between the two channels of the differential MEMS resonant accelerometer during the automatic amplitude control stage, and has no effect on flicker noise caused by differences in device manufacturing.

[0004] The second existing technology—using novel mechanical structures to reduce the nonlinear stiffness in MEMS resonators [see reference 2, C. Comi, A. Corigliano, G. Langfelder, A. Longoni, A. Tocchio and B. Simoni, “A Resonant Microaccelerometer With High Sensitivity Operating in an Oscillating Circuit,” Journal of Microelectromechanical Systems, vol. 19, no. 5, pp. 1140-1152, Oct. 2010. and Figure 2 [Mechanical Structure Diagram], the working principle of this device is based on the frequency changes of two resonant beams coupled to the verification mass. Under external acceleration, the movement of the proofmass generates axial loads on the beams, resulting in opposite stiffness changes, which in turn lead to the separation of their resonant frequencies. The innovative and optimized geometry of this device ensures a significant amplification of the axial load, thus achieving high sensitivity. Furthermore, its special "L"-shaped geometry allows the mechanical structure to greatly reduce nonlinearity caused by second-order coupling. The disadvantages of this prior art are as follows:

[0005] 1. This technology only targets flicker noise introduced by the amplitude mismatch between the two channels of the differential MEMS resonant accelerometer during the automatic amplitude control stage. It has no effect on flicker noise caused by other differences in device manufacturing.

[0006] 2. This technology does not address the fact that manufacturing defects can cause changes in the parameters of the accelerometer, thus affecting the accuracy of the accelerometer's measurement structure.

[0007] The third existing technology, [see reference 3, Silicon Oscillating Accelerometer (SOA) Architecture Based on Phase-Locked Loop (PPL), J. Zhao, X. Wang, Y. Zhao, G. M. Xia, AP. Qiu, Y. Su, and Y. P. Xu, “A 0.23-μg Bias Instability and 1-μg / √Hz Acceleration Noise Density Silicon Oscillating Accelerometer With Embedded Frequency-to-Digital Converter in PLL,” IEEE Journal of Solid-State Circuits, vol. 52, no. 4, pp. 1053–1065, 2017 and Figure 3 [Schematic diagram of SOA architecture based on phase-locked loop]. This technology eliminates the automatic amplitude control circuit (AAC), thereby eliminating uncorrelated flicker noise from the two AAC circuits. Furthermore, the drive voltage amplitudes of the two channels of the silicon oscillating accelerometer (SOA) are set by the same external low-reference noise. Therefore, flicker noise in the external reference is used as a common-mode signal input and is suppressed by the differential characteristics of the silicon oscillating accelerometer (SOA), thus achieving flicker noise suppression. The disadvantages of this prior art are as follows:

[0008] 1. Although the bias instability and power consumption of the circuit are significantly reduced in this scheme, the differential MEMS resonant accelerometer needs to be operated at an extremely low amplitude of about 0.01µm, which limits the application scope of this technology.

[0009] 2. This technology is based on the suppression of flicker noise when the two channels of the differential MEMS resonant accelerometer are operating with the same amplitude. However, it has no effect on flicker noise caused by the nonlinear stiffness mismatch between the two channels of the MEMS resonant accelerometer. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a calibration device and method for nonlinear mismatch in differential MEMS resonant accelerometers. This invention suppresses flicker noise introduced by the nonlinear stiffness mismatch between the two channels of the differential MEMS resonant accelerometer due to manufacturing defects, thereby further improving the performance of the differential MEMS resonant accelerometer. This invention suppresses flicker noise introduced by nonlinear stiffness mismatch without changing the mechanical architecture of the differential MEMS resonant accelerometer and maintains its high bandwidth and high signal-to-noise ratio characteristics.

[0011] The technical solution of the present invention is as follows:

[0012] On the one hand, the present invention provides a calibration device for nonlinear mismatch of differential MEMS resonant accelerometer, including a differential MEMS resonant accelerometer having a first channel and a second channel with the same structure, characterized in that it also includes a calibration control circuit and a test signal generator;

[0013] The first channel includes a MEMS resonator, a front-end amplifier, a digital-to-analog converter (DAC), a digital frequency detector, an amplitude detector, a subtractor, an adder, an automatic amplitude control circuit, a voltage gain amplifier, and an analog-to-digital converter (ADC). The output of the MEMS resonator is connected to the input of the ADC via the front-end amplifier. The output of the ADC is split into three parts: connected to the input of the digital frequency detector, the input of the amplitude detector, and the first input of the voltage gain amplifier. The output of the amplitude detector is connected to the negative input of the subtractor. The output of the subtractor is connected to the first input of the adder. The output of the adder is connected to the input of the automatic amplitude control circuit. The output of the automatic amplitude control circuit is connected to the second input of the voltage gain amplifier. The output of the voltage gain amplifier is connected to the input of the ADC. The output of the ADC is connected to the input of the MEMS resonator.

[0014] The calibration control circuit includes a first test signal response detector, a second test signal response detector, and an MPPT calibration controller. The input terminal of the first test signal response detector is connected to the output terminal of the digital frequency detector of the first channel via the first port of the first interface, and the output terminal of the first test signal response detector is connected to the first input terminal of the MPPT calibration controller. The input terminal of the second test signal response detector is connected to the output terminal of the digital frequency detector of the second channel via the second port of the first interface, and the output terminal of the second test signal response detector is connected to the second input terminal of the MPPT calibration controller. The MPPT calibration controller includes two output terminals: the first output terminal is connected to the positive input terminal of the subtractor of the first channel via the first port of the second interface, and the second output terminal is connected to the positive input terminal of the subtractor of the second channel via the second port of the second interface.

[0015] The test signal generator has two output terminals. The first output terminal is connected to the second input terminal of the adder of the first channel via the first port of the third interface, and the second output terminal is connected to the second input terminal of the adder of the second channel via the second port of the third interface.

[0016] The test signal generator can be a sine wave test signal generator, or a square wave test signal generator or a triangle wave test signal generator.

[0017] On the other hand, the present invention also provides a calibration method for a differential MEMS resonant accelerometer using the above-mentioned calibration device, characterized in that the method includes the following steps:

[0018] 1) Initialization: Place the differential MEMS resonant accelerometer on a horizontal platform. Connect the upper and lower surfaces of the measured mass block to the resonant beams of the first and second channel MEMS resonators, respectively, forming the y-axis direction. The direction perpendicular to the y-axis is the x-axis direction. Start the device and set the frequency threshold F according to the actual situation. th The sinusoidal test signal generator inputs test signals with equal voltage amplitudes to the second input terminals of the adders in both channels via the third interface. Furthermore, the same initial reference voltage V is input to the positive input terminals of the subtractors in both channels. REF1 V REF2 .

[0019] 2) After a period of time, each of the two channels of the differential MEMS resonant accelerometer generates a stable frequency ω1 and ω2, which are respectively input to the MPPT calibration controller via the frequency detector, the first interface, the first test signal response detector, and the second test signal response detector. The first and second test signal response detectors read the sinusoidal signals coupled in the output frequencies of the two channels.

[0020] 3) The sinusoidal signal coupled in the output frequency of the two channels is input to the MPPT calibration controller and the corresponding difference is calculated. Then, according to the difference, the reference voltage of the two channels of the differential MEMS resonant accelerometer is adjusted through the second interface. That is, if the test signal coupled in the output frequency of a certain channel is large, the reference voltage of that channel is reduced accordingly.

[0021] 4) After a period of stabilization, if the frequency difference of the frequency-coupled test signals output from the two channels is greater than the frequency threshold F... th (Return to step 3) If the frequency difference of the sinusoidal signals coupled to the output frequencies of the two channels is less than or equal to the frequency threshold F... th Then proceed to the next step;

[0022] 5) Complete the self-calibration of nonlinear distortion.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. To address the flicker noise caused by the nonlinear mismatch in stiffness between the two channels of the differential MEMS resonant accelerometer, only a sinusoidal test signal needs to be added to the original accelerometer, ensuring that the design has the characteristics of low cost and low power consumption.

[0025] 2. While suppressing flicker noise introduced by nonlinear stiffness mismatch, the high bandwidth and high signal-to-noise ratio characteristics of the original differential MEMS resonant accelerometer can be maintained without introducing other noise. This invention suppresses flicker noise introduced by nonlinear stiffness mismatch between the two channels of the differential MEMS resonant accelerometer due to manufacturing defects, thus improving the performance of the differential MEMS resonant accelerometer. Suppressing flicker noise introduced by nonlinear stiffness mismatch does not require changing the mechanical architecture of the differential MEMS resonant accelerometer of this invention, and maintains its high bandwidth and high signal-to-noise ratio characteristics.

[0026] 3. This invention can further reduce its cost and power consumption. Attached Figure Description

[0027] Figure 1 This is the working principle of chopper stabilization technology in automatic amplitude control circuits to suppress incoherent noise.

[0028] Figure 2 Schematic diagram of the mechanical structure;

[0029] Figure 3 A schematic diagram of an SOA architecture based on a phase-locked loop (PLL).

[0030] Figure 4 This is a schematic diagram of the calibration device for nonlinear mismatch of differential MEMS resonant accelerometer according to the present invention;

[0031] Figure 5 yes Figure 4 Control flowchart of the MPPT calibration controller;

[0032] Figure 6 This is a schematic diagram of the test signal points of the present invention;

[0033] Figure 7 This is a system block diagram of the differential MEMS resonant accelerometer of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and technical effects of this invention clearer, the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the terminology used in this description is for ease of description and simplification only, and therefore should not be construed as limiting the scope of this application.

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0036] Example

[0037] Please refer to the following for adoption: Figure 4 , Figure 4 This is a schematic diagram of the calibration device for nonlinear mismatch of differential MEMS resonant accelerometer according to the present invention. As can be seen from the figure, the differential MEMS resonant accelerometer 1 of the present invention includes a first channel 11 and a second channel 12 with the same structure. Its feature is that it also includes a calibration control circuit 2 and a sine test signal generator 3. In this embodiment, the test signal generator 3 is a sine test signal generator.

[0038] The first channel 11 includes a MEMS resonator 1101, a front-end amplifier 1102, a digital-to-analog converter 1103, a digital frequency detector 1104, an amplitude detector 1105, a subtractor 1106, an adder 1107, an automatic amplitude control circuit 1108, a voltage gain amplifier 1109, and an analog-to-digital converter 1110. The output of the MEMS resonator 1101 is connected to the input of the digital-to-analog converter 1103 via the front-end amplifier 1102. The output of the digital-to-analog converter 1103 is divided into three parts: one connected to the input of the digital frequency detector 1104, the other to the input of the amplitude detector 1105, and the first input of the voltage gain amplifier 1109. The amplitude detector 1105 is connected to the negative input terminal 11061 of the subtractor 1106. The output terminal 11063 of the subtractor 1106 is connected to the first input terminal 11071 of the adder 1107. The output terminal 11073 of the adder 1107 is connected to the input terminal of the automatic amplitude control circuit 1108. The output terminal of the automatic amplitude control circuit 1108 is connected to the second input terminal 11092 of the voltage gain amplifier 1109. The output terminal 11093 of the voltage gain amplifier 1109 is connected to the input terminal of the analog-to-digital converter 1110. The output terminal of the analog-to-digital converter 1110 is connected to the input terminal of the MEMS resonator 1101.

[0039] The calibration control circuit 2 includes a first test signal response detector 21, a second test signal response detector 22, and an MPPT calibration controller 23. The input terminal of the first test signal response detector 21 is connected to the output terminal of the digital frequency detector 1104 of the first channel 11 via the first port 41 of the first interface 4, and the output terminal of the first test signal response detector 21 is connected to the first input terminal of the MPPT calibration controller 23. The input terminal of the second test signal response detector 22 is connected to the output terminal of the digital frequency detector 1204 of the second channel 12 via the second port 42 of the first interface 4, and the output terminal of the second test signal response detector 22 is connected to the second input terminal of the MPPT calibration controller 23. The MPPT calibration controller 23 includes two output terminals: the first output terminal is connected to the positive input terminal 11062 of the subtractor 1106 of the first channel 11 via the first port 51 of the second interface 5, and the second output terminal is connected to the positive input terminal 12062 of the subtractor 1206 of the second channel 12 via the second port 52 of the second interface 5.

[0040] The test signal generator 3 has two output terminals. The first output terminal 31 is connected to the second input terminal 11072 of the adder 1107 of the first channel 11 via the first port 61 of the third interface 6. The second output terminal 32 is connected to the second input terminal 12072 of the adder 1207 of the second channel 12 via the second port 62 of the third interface 6.

[0041] The calibration method for the differential MEMS resonant accelerometer using the aforementioned calibration device for nonlinear mismatch includes the following steps:

[0042] 1) Initialization: Place the differential MEMS resonant accelerometer 1 on a horizontal platform. The upper and lower surfaces of the mass block being measured are connected to the resonant beams of the MEMS resonator 1101 of the first channel 11 and the MEMS resonator 1201 of the second channel 12, respectively, forming the y-axis direction. The direction perpendicular to the y-axis is the x-axis direction. Start the device and set the frequency threshold F according to the actual situation. th The sinusoidal test signal generator 3 inputs test signals with equal voltage amplitudes to the second input terminals 11072 and 12072 of the adders 1107 and 1207 of the two channels 11 and 12 respectively via the third interface 6. Furthermore, the same initial reference voltage V is input to the positive input terminals 11062 and 12062 of the subtractors 1106 and 1206 of the two channels 11 and 12 respectively. REF1 V REF2 ;

[0043] 2) After a period of time, the two channels 11 and 12 of the differential MEMS resonant accelerometer 1 each generate a stable frequency ω1 and ω2, which are respectively input to the MPPT calibration controller 23 via the frequency detectors 1104 and 1204, the first interface 4, the first test signal response detector 21, and the second test signal response detector 22. The first test signal response detector 21 and the second test signal response detector 22 read the sinusoidal signals coupled in the output frequencies of the two channels;

[0044] 3) The sinusoidal signal coupled in the output frequency of the two channels is input to the MPPT calibration controller 23 and the corresponding difference is calculated. Then, according to the difference, the reference voltages of the two channels 11 and 12 of the differential MEMS resonant accelerometer 1 are adjusted through the second interface 5 respectively. That is, if the test signal coupled in the output frequency of a certain channel is large, the reference voltage of that channel is reduced accordingly.

[0045] 4) After a period of stabilization, if the frequency difference of the frequency-coupled test signals output from the two channels is greater than the frequency threshold F... th (Return to step 3) If the frequency difference of the sinusoidal signals coupled to the output frequencies of the two channels is less than or equal to the frequency threshold F... th Then proceed to the next step;

[0046] 5) Complete the self-calibration of nonlinear distortion.

[0047] 1. The main purpose of this invention is to eliminate flicker noise (n) introduced by the reference voltage of the two channels of a differential MEMS resonant accelerometer. REF );

[0048] 2. The main technical point is to add a sinusoidal test signal to the reference voltage of the two channels of the differential MEMS resonant accelerometer and use the maximum power point tracking (MPPT) algorithm to adjust the reference voltage of the two channels to maximize the elimination of nonlinear distortion.

[0049] 3. The basic principle of this invention is that adding a sinusoidal test signal to the reference voltage of the two channels of a differential MEMS resonant accelerometer will cause the frequency outputs of the two channels of the accelerometer to couple with a sinusoidal signal. Furthermore, this signal has an amplitude and frequency that match the test signal.

[0050] 4. The working principle diagram of the MPPT calibration controller is as follows: Figure 5 As shown, this mainly includes initializing the reference voltage V of the two channels of the differential MEMS resonant accelerometer. REF1 and V REF2 The difference between the coupled sinusoidal signals in the output of the two channels is measured after a specific time, and the reference voltages of the two channels are adjusted in three steps according to the difference with a specific step size.

[0051] 5. Under this design, regardless of the specific parameters of the two channels of the differential MEMS resonant accelerometer, the MPPT calibration controller can adjust the reference voltage of the two channels of the differential MEMS resonant accelerometer to a suitable value after a certain period of time, thereby eliminating the nonlinear distortion of the two channels to the greatest extent.

[0052] The point where the test signal is applied can change. For example... Figure 6 As shown, the test signal can be applied to either point 1 or point 2. In the technical solution, the test signal is applied to point 1, but applying the test signal to point 2 can also achieve adjustment of the nonlinear distortion of the differential MEMS resonant accelerometer; however, the amplitude of the test signal will differ after passing through the integrator. Figure 6 The automatic amplitude control circuit (1108) consists of a PI controller and a first-order low-pass filter, wherein the system function of the PI controller is: Where k P It is a proportionality coefficient. (τ I It is the integration time constant); the system function of the first-order low-pass filter is Where τ LF Let represent the time constant of the first-order low-pass filter. Here, 's' represents the Laplace transform operator, often used to represent the system function of a system. Then, the system function of the automatic amplitude control circuit (1108) is: Point 2 involves splitting the automatic amplitude control circuit (1108) into two systems. The system function of system 1 is... The system function of system 2 is Point 2 is the location where the two separated systems connect. Point 1 corresponds to the location... Figure 4 The second input terminal (11072) of the adder (1107).

[0053] Figure 7 This is a system block diagram of the differential MEMS resonant accelerometer of this invention. The equation of motion for the detected mass block is:

[0054]

[0055] Where x is the displacement, c0 is the damping coefficient, m0 is the equivalent mass of the resonator mass block, k0 and k2 are the linear spring coefficient and the second-order nonlinear spring coefficient, respectively, and F is the force applied to the resonant beam. Therefore, the frequency of the resonant peak will be affected by the displacement amplitude, which is defined as the amplitude enhancement (AS) effect, given by equation (2):

[0056]

[0057] Where x0 is the displacement amplitude, ω0 is the resonant frequency without nonlinear stiffness, controlled by the linear spring coefficient k0 and the equivalent mass m0, and ω'0 is the resonant frequency at x0.

[0058] Each channel of the differential MEMS resonant accelerometer 1 consists of a MEMS resonator 1101 and its oscillation sustaining circuit. When the detected mass block is accelerated along the y-axis, it generates tensile and compressive forces on the two resonant beams, thereby changing the linear spring coefficient k0 of the resonator 1101, resulting in different resonant frequencies of the resonators 1101 on both sides of the mass block. The difference in resonant frequencies between the two channels is proportional to the acceleration input to the mass block; however, in addition to the linear spring coefficient k0, the second-order nonlinear spring coefficient k2 also affects the resonator 1101. The actual motion equation of the resonator 1101 along the x-axis is given by equation (1). Therefore, the resonant frequency will be affected by the displacement amplitude x0. The frequency under the amplitude enhancement (AS) effect is given by equation (2). The displacement amplitude x0 and the reference voltage V used for amplitude control are... REF It is linearly dependent. From N 1 / , The transfer function to the oscillation amplitude is given by equation (3):

[0059]

[0060] Where 'a' is the feedback gain of the entire resonant system when the open-loop gain is much greater than 1. Therefore, the effect of 1 / f,ref noise leakage on the resonant frequency can be derived from equations (2) and (3) to form equation (4):

[0061]

[0062] Equation (4) shows how 1 / f,ref noise leakage affects the resonant frequency through the AS effect, which is the basis for the self-calibration of the silicon oscillating accelerometer of this invention.

[0063] The calibration control circuit 2 includes a first test signal response detector 21, a second test signal response detector 22, and an MPPT (maximum power point tracking) calibration controller 23. The sinusoidal test signal generator 3 is connected to the second input terminals 11072 and 12072 of the adders 1107 and 1207 via a third interface 6, which is equivalent to coupling a sinusoidal test signal onto the reference voltages of the two channels 11 and 12. The digital frequency detectors 1104 and 1204 read the output frequencies ω1 and ω2 of the first channel 11 and the second channel 12, respectively, and transmit them to the first test signal corresponding detector 21 and the second test signal corresponding detector 22 through the first interface 4. The first test signal corresponding detector 21 and the second test signal corresponding detector 22 then transmit the detection results to the MPPT calibration controller 23. The MPPT calibration controller 23 then inputs the processed results to the subtractors 1106 and 1206 through the second interface 5 via the second input terminals 11062 and 12062, respectively, to equivalently adjust and output the reference voltage V. REF .

[0064] Considering that the resonant frequencies of most resonators 1101 and 1202 are approximately 20,000 Hz, if the frequency fluctuation difference between the two channels is designed to be less than D, then F th It is given by the following formula:

[0065]

[0066] Among them, f clk It is the frequency of the reference clock, K CIC This is the gain of CIC. The MPPT control circuit 23 provides an adjusted V for each channel. REFn .therefore, The reference voltage of the lower channel is continuously increased until it reaches a point where both channels... Almost identical. F th The final value needs to be adjusted appropriately based on the actual effect. In this embodiment, the frequency threshold F... th The frequency is set to 0.035Hz.

[0067] Experiments show that this invention suppresses flicker noise introduced by the nonlinear stiffness mismatch between the two channels of the differential MEMS resonant accelerometer due to manufacturing defects, thereby improving the performance of the differential MEMS resonant accelerometer. Suppressing flicker noise introduced by the nonlinear stiffness mismatch does not require changing the mechanical architecture of the differential MEMS resonant accelerometer of this invention, and maintains the high bandwidth and high signal-to-noise ratio characteristics of the differential MEMS resonant accelerometer of this invention.

Claims

1. A calibration device for nonlinear mismatch of a differential MEMS resonant accelerometer, comprising a differential MEMS resonant accelerometer (1) consisting of a first channel (11) and a second channel (12) having the same structure, characterized in that, It also includes a calibration control circuit (2) and a test signal generator (3); The first channel (11) includes a MEMS resonator (1101), a front-end amplifier (1102), an analog-to-digital converter (1103), a digital frequency detector (1104), an amplitude detector (1105), a subtractor (1106), an adder (1107), an automatic amplitude control circuit (1108), a voltage gain amplifier (1109), and a digital-to-analog converter (1110). The output of the MEMS resonator (1101) is connected to the input of the analog-to-digital converter (1103) via the front-end amplifier (1102). The output of the analog-to-digital converter (1103) is divided into three parts: one is connected to the input of the digital frequency detector (1104), the other to the input of the amplitude detector (1105), and the first input of the voltage gain amplifier (1109). 1) The output terminal of the amplitude detector (1105) is connected to the negative input terminal (11061) of the subtractor (1106), the output terminal (11063) of the subtractor (1106) is connected to the first input terminal (11071) of the adder (1107), the output terminal (11073) of the adder (1107) is connected to the input terminal of the automatic amplitude control circuit (1108), the output terminal of the automatic amplitude control circuit (1108) is connected to the second input terminal (11092) of the voltage gain amplifier (1109), the output terminal (11093) of the voltage gain amplifier (1109) is connected to the input terminal of the digital-to-analog converter (1110), and the output terminal of the digital-to-analog converter (1110) is connected to the input terminal of the MEMS resonator (1101). The calibration control circuit (2) includes a first test signal response detector (21), a second test signal response detector (22), and a maximum power point tracking (MPPT) calibration controller (23). The input terminal of the first test signal response detector (21) is connected to the output terminal of the digital frequency detector (1104) of the first channel (11) via the first port (41) of the first interface (4), and the output terminal of the first test signal response detector (21) is connected to the first input terminal of the MPPT calibration controller (23). The input terminal of the second test signal response detector (22) is connected to the second port (41) of the first interface (4). 42) The output terminal of the digital frequency detector (1204) of the second channel (12) is connected to the output terminal of the second test signal response detector (22), and the output terminal of the second test signal response detector (22) is connected to the second input terminal of the MPPT calibration controller (23). The MPPT calibration controller (23) includes two output terminals: the first output terminal is connected to the positive input terminal (11062) of the subtractor (1106) of the first channel (11) via the first port (51) of the second interface (5), and the second output terminal is connected to the positive input terminal (12062) of the subtractor (1206) of the second channel (12) via the second port (52) of the second interface (5); The test signal generator (3) has two output terminals. The first output terminal (31) is connected to the second input terminal (11072) of the adder (1107) of the first channel (11) via the first port (61) of the third interface (6). The second output terminal (32) is connected to the second input terminal (12072) of the adder (1207) of the second channel (12) via the second port (62) of the third interface (6).

2. The calibration device for nonlinear mismatch of differential MEMS resonant accelerometers according to claim 1, characterized in that, The test signal generator (3) can be a sine wave test signal generator, or a square wave test signal generator or a triangular wave test signal generator.

3. A self-calibration method for the differential MEMS resonant accelerometer using the calibration device for nonlinear mismatch of the differential MEMS resonant accelerometer as described in claim 1, characterized in that... The method includes the following steps: 1) Initialization: Place the differential MEMS resonant accelerometer (1) on a horizontal platform. The upper and lower surfaces of the mass block being measured are connected to the resonant beams of the MEMS resonator (1101) of the first channel (11) and the MEMS resonator (1201) of the second channel (12), respectively, forming the y-axis direction. The direction perpendicular to the y-axis is the x-axis direction. Start the device and set the frequency threshold according to the actual situation. The test signal generator (3) inputs test signals with equal voltage amplitude to the second input terminals (11072, 12072) of the adders (1107, 1207) of the two channels (11, 12) respectively through the third interface (6); and inputs the same initial reference voltage V to the positive input terminals (11062, 12062) of the subtractors (1106, 1206) of the two channels (11, 12). REF1 V REF2 ; 2) After a period of time, the two channels (11, 12) of the differential MEMS resonant accelerometer (1) each generate a stable frequency, which is input to the MPPT calibration controller (23) through the digital frequency detector (1104, 1204), the first interface (4), the first test signal response detector (21), and the second test signal response detector (22), respectively; the first test signal response detector (21) and the second test signal response detector (22) read the sinusoidal signal coupled in the output frequency of the two channels; 3) The sinusoidal signal coupled in the output frequency of the two channels is input to the MPPT calibration controller (23) and the corresponding difference is calculated. Then, according to the difference, the reference voltage of the two channels (11, 12) of the differential MEMS resonant accelerometer (1) is adjusted through the second interface (5). That is, if the test signal coupled in the output frequency of a certain channel is large, the reference voltage of that channel is reduced accordingly. 4) After a period of stabilization, if the frequency difference of the test signal coupled with the output frequency in the two channels is greater than the frequency threshold, return to step 3); if the frequency difference of the sinusoidal signal coupled with the output frequency in the two channels is less than or equal to the frequency threshold, proceed to the next step. 5) Complete the self-calibration of nonlinear distortion.

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