A three-axis mems accelerometer closed loop readout circuit

Abstract

The application discloses a three-axis MEMS accelerometer closed-loop readout circuit, which comprises three single-axis closed-loop readout circuits, the three single-axis closed-loop readout circuits are connected with X, Y and Z axes of the three-axis MEMS accelerometer respectively, output ends of the three single-axis closed-loop readout circuits are connected with data input ends of an accelerometer signal digital quantization module, an output end of the accelerometer signal digital quantization module is connected with an input end of a digital processing module, and an output end of the digital processing module digitally outputs an accelerometer signal. Signal simulation and digital output can be realized for each axis respectively; closed-loop control or open-loop control can be selected for each axis readout circuit; meanwhile, an internal integrated memory and a control circuit are arranged, parameters of the three-axis readout circuit can be flexibly configured, accelerometer processing errors, packaging errors and assembly errors can be timely adjusted, so that the device yield is improved; meanwhile, signal simulation output and digital output are compatible, and user use is facilitated.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical control technology, and in particular to a closed-loop readout circuit for a triaxial MEMS accelerometer. Background Technology

[0002] MEMS (Micro-Electro-Mechanical Systems) accelerometers operate based on Newtonian mechanics principles. A micro-mass block senses inertial acceleration, causing the cantilever beam to deform under stress, resulting in a corresponding change in capacitance. The circuit detects this capacitance change and thus indirectly obtains acceleration data. This type is also called a capacitive MEMS accelerometer, and its advantages include high sensitivity, low noise, small drift, small size, and low cost.

[0003] Internal structure of MEMS accelerometer (e.g.) Figure 1 The accelerometer is extremely precise, containing a mass block, comb teeth, beams, and gas components. The mass block is typically required to be on the order of 10⁻⁷ g, the comb tooth gap to be below 8 μm, and the gas pressure to be controlled at a low level on the order of 10⁻³ Pa. Even at normal pressure, the gas pressure must not fluctuate too much during use. However, MEMS manufacturing introduces process deviations, axial deviations, and batch deviations. These process errors cause parameters to deviate from design requirements; even between different batches or along different axes, inconsistencies can exist, leading to inconsistencies in the closed-loop control parameters, zero bias, and scale factor of the MEMS accelerometer. Furthermore, packaging and mounting errors also significantly impact device consistency. Therefore, measures need to be taken to improve device consistency and yield in the accelerometer readout circuit. Summary of the Invention

[0004] The purpose of this invention is to provide a closed-loop readout circuit for a three-axis MEMS accelerometer.

[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0006] The present invention includes three single-axis closed-loop readout circuits, which are respectively connected to the X, Y, and Z axes of the triaxial MEMS accelerometer. The output terminals of the three single-axis closed-loop readout circuits are connected to the data input terminal of the accelerometer signal digital quantization module. The output terminal of the accelerometer signal digital quantization module is connected to the input terminal of the digital processing module. The output terminal of the digital processing module digitally outputs the accelerometer signal.

[0007] Furthermore, the single-axis closed-loop readout circuit comprises a capacitor-to-voltage conversion circuit, a low-pass filter, a proportional-integral-differential (PID) controller, a mode control circuit, an accelerometer signal quantization module, and a self-calibration module. The capacitor-to-voltage conversion circuit is connected to the triaxial MEMS accelerometer, and its output is connected to the low-pass filter. The output of the low-pass filter is connected to the PID controller. The output of the PID controller is connected to the mode control circuit. The output of the mode control circuit is connected to the accelerometer signal quantization module. The output of the capacitor-to-voltage conversion circuit is also connected to the self-calibration module.

[0008] As an improvement, the single-axis closed-loop readout circuit also includes a feedback branch, which consists of a digital-to-analog converter, an analog adder, and a high-voltage feedback circuit. The two inputs of the analog adder are connected to the outputs of the digital-to-analog converter and the proportional-integral-derivative controller, respectively. The output of the analog adder is connected to the high-voltage feedback drive module, and the output of the high-voltage feedback drive module is connected to the force balance input of the accelerometer as a feedback output.

[0009] Specifically, the capacitor voltage conversion circuit includes a differential operational amplifier and a demodulator connected to the output of the differential operational amplifier. An amplification feedback capacitor is connected between the input and output of the differential operational amplifier, and a zero-bias compensation capacitor is connected in series between the two inputs of the differential operational amplifier.

[0010] Preferably, it also includes a temperature sensor and a temperature signal analog-to-digital converter connected to the temperature sensor, with the output of the temperature signal analog-to-digital converter connected to a digital processing module.

[0011] Preferably, the communication interface of the digital processing module includes one or more of a variety of digital communication interfaces such as I2C, SPI, and RS485.

[0012] Specifically, the digital processing module includes a memory and a memory control module, wherein the memory is a one-time programmable memory or a multiple-erasable and rewritable memory.

[0013] The beneficial effects of this invention are:

[0014] This invention relates to a closed-loop readout circuit for a three-axis MEMS accelerometer. Compared with existing technologies, this invention integrates the MEMS structure and the readout circuit together during overall device parameter configuration, enabling system parameter setting and calibration to form a closed-loop control adjustment for the accelerometer. Each of the three axes can independently achieve analog and digital signal output. Each axial readout circuit can be individually selected for closed-loop or open-loop control. Simultaneously, it integrates internal memory and control circuitry, allowing for flexible configuration of the parameters of the three axial readout circuits and timely adjustment of accelerometer processing errors, packaging errors, and assembly errors, thereby improving device yield. It also supports both analog and digital signal output for user convenience. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the internal structure of the MEMS accelerometer described in this invention;

[0016] Figure 2 This is a schematic diagram of a specific embodiment of the triaxial closed-loop accelerometer readout circuit described in this invention;

[0017] Figure 3 This is a schematic diagram of a specific embodiment of the single-axis readout circuit described in this invention;

[0018] Figure 4 This is a schematic diagram of a specific embodiment of the C / V conversion circuit described in this invention;

[0019] Figure 5 This is a schematic diagram of a specific embodiment of the AMUX analog multiplication circuit described in this invention;

[0020] Figure 6 This is a schematic diagram of the force analysis of the MEMS structure mass block described in this invention.

[0021] In the diagram: 1-mass block, 2-elastic beam, 3-moving tooth, 4-fixed tooth, 5-anchor point (fixed body), 6-small gap between comb teeth, 7-large gap between comb teeth, MEMS-triaxial MEMS structure, POR-power supply detection circuit, REF-reference circuit, LDO-regulated output circuit, CPP-high voltage generation circuit, VDDLGEN-digital power generation circuit, TS-temperature sensor, CLKGEN-clock generation circuit, T_ADC-digital quantization circuit for temperature signal, A_ADC-accelerometer signal. Digital quantization circuit, DPM - digital signal processing module, C / V - capacitor (charge) voltage conversion circuit, LPF - low-pass filter circuit, PID - proportional-integral-derivative control circuit, SUM - analog adder circuit, HVF - high voltage feedback circuit, ACU - automatic calibration circuit, AMUX - analog multiplier circuit, DAC - digital-to-analog converter circuit, 101 - differential operational amplifier, 102 - analog multiplier, 103 - analog switch, 104 - NOR gate, 105 - NOT gate, Fe - electrostatic force, Fa - inertial force. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0023] This invention applies to the fabrication of a triaxial MEMS structure and the readout circuit together as a device. It can be packaged at the device level or at the PCB level, but device-level packaging offers superior performance. During system parameter setting and calibration, system parameters such as the accelerometer closed-loop control circuit can be flexibly configured to compensate for the effects of machining, packaging, and assembly errors in the triaxial MEMS structure, thereby improving the overall yield of the accelerometer device.

[0024] The MEMS triaxial closed-loop accelerometer readout circuit described in this invention, such as... Figure 2 As shown, it includes single-axis acceleration readout circuits for X, Y, and Z axes; it also includes an acceleration signal digital quantization module A_ADC connected to the single-axis acceleration readout circuits, and the acceleration signal digital quantization module is also connected to a digital processing module DPM; the analog signals of the three-axis accelerometer are output through the output terminals XOUT / YOUT / ZOUT respectively; the digital signals of the three-axis accelerometer are output through the DOUT output terminal.

[0025] like Figure 3As shown, the single-axis acceleration readout circuit includes a capacitor-to-voltage conversion circuit (C / V) connected to the MEMS accelerometer detection terminal, a low-pass filter (LPF) circuit connected to the C / V circuit, and a proportional-integral-derivative (PID) control circuit connected to the LPF output terminal. The PID output terminal is connected to an analog multiplier circuit (AMUX). The AMUX output terminal is connected to an A_ADC. The C / V circuit output terminal is connected to a self-calibrating ACU circuit. The C / V input terminal serves as the signal input terminal 1 of the single-axis acceleration readout circuit. The AMUX output terminal serves as the signal output terminal 3 of the single-axis acceleration readout circuit. The AMUX selects the accelerometer signal output mode (analog mode / digital mode) through the input signal terminal 4.

[0026] The single-axis acceleration readout circuit also includes a feedback branch, which comprises a digital-to-analog converter (DAC) and an analog summing circuit (SUM). The two inputs of the SUM circuit are connected to the outputs of the DAC and the PID controller, respectively. The output of the SUM circuit is connected to a high-voltage feedback circuit (HVF), and the output of the HVF serves as feedback output 2, connected to the force balance input of the accelerometer. The input of the DAC circuit is the digital adjustment input 7 of the single-axis acceleration readout circuit, and it is connected to the digital processing module via parameter output / input buses XRG2A, YRG2A, and ZRG2A. Figure 2 As shown.

[0027] The digital signal output by the Digital Processing Module (DPM) is sent to a host computer, such as a computer or microcontroller, through the device's digital interface. The host computer can then calibrate the device's parameters and perform further processing and analysis on the acceleration signal.

[0028] Among them, the capacitor voltage conversion circuit C / V (such as Figure 4 The function of the circuit shown is to convert the differential capacitance change of the MEMS accelerometer into a differential voltage change. The accelerometer head senses the acceleration signal and converts it into a differential capacitance signal. In this field, the differential capacitance converted from 1g of acceleration is called the sensitivity of the meter, denoted by ΔC (ΔC = CST - CSB), with units of pF / g. The capacitor-to-voltage conversion circuit converts the differential capacitance signal into a voltage signal, and the conversion gain is denoted by Gcv, expressed as follows:

[0029]

[0030] Where Aop and Aon are the positive and negative output voltages of the C / V module, respectively; Cf is the feedback capacitor of the C / V module; and Vr is the MASS carrier amplitude of the C / V circuit. Optionally, Cf can be digitally configured to select the corresponding C / V gain. Figure 4In one specific implementation of the capacitor-to-voltage (C / V) conversion circuit, STOP and SBOT serve as the positive and negative inputs of the differential operational amplifier. The output of the differential operational amplifier 101 is connected to the input of the demodulator 102, and the output of the demodulator 102 is the C / V output terminals AOP and AON. Capacitors C0 and C0T are connected in parallel to form a capacitor combination CT, and capacitors C0 and C0B are connected in parallel to form a capacitor combination CB. CT / CB and the equivalent capacitance CST / CSB of MEMS structure detection form a capacitor bridge.

[0031] like Figure 4 As shown, the upper and lower detection plates of the MEMS accelerometer form a differential capacitor pair with the mass block. An increase in one capacitor results in an equal decrease in the other, i.e., CST - CSB = ΔC. The mass block is connected to the MASS terminal of C / V, and the upper and lower detection plates are connected to STOP and SBOT (positive and negative inputs of the differential operational amplifier) ​​of C / V, respectively. The clock required by the system is generated by an oscillator or a phase-locked loop frequency multiplier circuit CLKGEN. The digital processing module DPM generates the carrier signal required by C / V and connects it to MASS and CTR. The carrier signal modulates and converts the change in differential capacitance between the mass block and the upper and lower detection plates into a high-frequency current signal. This current signal is integrated through the feedback capacitor Cf and converted into a voltage signal, which is then demodulated to a low-frequency output by demodulator 2. In other words, the change in differential capacitance leads to a change in the op-amp input current, ultimately reflected in the waveform changes at the positive and negative output terminals AOP and AON. The C / V circuit employs a capacitive bridge detection method. The upper electrode and mass block of the MEMS structure constitute the upper electrode capacitor, i.e., the equivalent detection capacitor CST of the accelerometer. The lower electrode and mass block constitute the lower electrode capacitor, i.e., the equivalent detection capacitor CSB of the accelerometer. These two capacitors, together with the capacitor groups CT and CB in the C / V circuit, form a capacitive bridge. When there is no acceleration, CST = CT = C0 + C0T, and CSB = CB = C0 + C0B. At this point, the capacitive bridge is in an optimal matching state, resulting in optimal C / V operation and the best performance in terms of noise and nonlinearity. Capacitor C0 is generally called the matching capacitor, and C0T / C0B are called zero-bias compensation capacitors. In the circuit, they are designed as capacitor arrays, and different capacitance values ​​can be selected by the state of the parallel switches in the array. These switches can be configured through the digital processing module DPM.

[0032] The differential voltage signal output from the C / V converter is connected to the input of a low-pass filter (LPF). The output of the LPF is connected to the input of a proportional-integral-derivative (PID) controller. The PID input is connected to an analog multiplier (AMUX) and an analog adder (SUM). The LPF filters out high-frequency glitches in the voltage signal and outputs the voltage value corresponding to the capacitance change. The PID controller performs PID control on the differential signal, and the PID output voltage serves as the analog acceleration voltage output. The output acceleration voltage value characterizes the magnitude and direction of acceleration. This voltage is also output to the analog multiplier (AMUX) and the analog adder (SUM), entering the feedback branch.

[0033] The typical transfer function of a proportional-integral-derivative (PID) controller is shown in the following equation:

[0034]

[0035] As can be seen from the PID transfer function, PID control mainly consists of three terms: P, the proportional gain term, which provides a full-frequency gain; I, the integral gain term, which provides a large low-frequency gain, improving the low-frequency control accuracy of the closed-loop system; and D, the derivative term, which provides stability compensation, where s is the frequency and N is the derivative term filter parameter used to improve stability. P, I, D, and N are configurable parameter arrays in the circuit design and can all be customized through DPM. When the system operates in open-loop mode, the integral and derivative terms are disabled via DPM configuration, leaving only the proportional term active.

[0036] The analog multiplication circuit AMUX selects the output of the acceleration voltage value. Depending on the control signal, it selects to output the analog acceleration voltage value output by the proportional-integral-derivative (PID) controller, or the digital acceleration signal of the DPM controller, and can adjust the polarity of the output signal.

[0037] like Figure 5 The diagram shows a specific implementation of the analog multiplication circuit AMUX. Figure 5 In the diagram, the left side represents the input signal terminal and the control signal terminal, while the right side represents the output signal terminal. The mode control circuit consists of multiple inverters 105 and NOR gates 104 connected together to form control logic, which controls the switching of the analog switch 104. Depending on the control signal, different output signals are selected to be output at different output terminals.

[0038] The system can switch between analog and digital modes via mode control signals. These signals can originate from system pin inputs or from the DPM configuration. In analog mode, unused digital circuits such as T_ADC and A_ADC can be disabled using the mode control signals, thereby reducing device power consumption. In closed-loop control mode, when the analog multiplier circuit AMUX directly outputs the analog acceleration voltage value from the proportional-integral-derivative controller (PID controller) to the output pin, it is in analog mode. In this case, the digital section will stop working, thus saving power.

[0039] The analog multiplication circuit AMUX is a 2-to-1 multiplexer that can output an analog acceleration voltage to a device pin or to the acceleration signal digital quantization module A_ADC. The acceleration signal digital quantization module A_ADC converts the acceleration voltage signal into a digital signal, which is then calibrated and compensated in the digital processing module DPM.

[0040] After receiving the digital signal, the Digital Processing Module (DPM) calculates and outputs a control signal to the self-calibration module (ACU) using its built-in algorithm. Employing a successive approximation method, it automatically calculates the matched content C0 and the zero-bias compensation capacitor C0T / C0B values. Then, through the configuration register, it opens the corresponding capacitor array to ensure good C / V matching, achieving zero-bias calibration and capacitor matching using the capacitance method. Under this good matching (CST = CT = C0 + C0T, CSB = CB = C0 + C0B), when there is no acceleration (CST = CST), the C / V output voltage is 0.

[0041] The accelerometer signal digital quantization module A_ADC can be implemented by a multiplexed analog-to-digital converter or a single digital-to-analog converter circuit, using time-division multiplexing to achieve digital conversion of X / Y / Z acceleration signals. In the DPM (Digital Processing Module), calibration and compensation typically include zero-bias calibration of the digital acceleration signal, zero-bias temperature compensation, scale factor calibration, scale factor temperature compensation, nonlinearity compensation, and digital filtering, etc. After data processing, the DPM outputs the data to the host computer via an interface. The software algorithms for implementing the above functions in the DPM are all mature existing technologies and will not be elaborated upon here.

[0042] In closed-loop control mode, the analog voltage output from the DAC and the analog voltage output from the PID controller are summed and sent to the HVF input. The HVF converts the low-voltage input to a high-voltage input, and the generated differential high-voltage signal is applied to the drive electrode of the meter, forming a driving force to counteract the measured acceleration force, thus achieving a force balance state. Figure 6The diagram illustrates the force analysis of the MEMS structure mass block. When the device is subjected to acceleration, the mass block moves downward due to the force Fa. High-voltage drive signals are applied to the upper and lower drive plates respectively. At this time, a large voltage is applied to the upper plate and a small voltage is applied to the lower plate. The electrostatic net force Fe formed on the mass block is equal in magnitude and opposite in direction to the force on the mass block, pulling the mass block to the equilibrium position, which is exactly in the middle of the upper and lower plates. Finally, the two forces are equal, and the mass block is in the force equilibrium position. The system will then reach a stable state. At this time, the system outputs XOUT / YOUT / ZOUT are proportional to the system input acceleration.

[0043] The gain and high-voltage common-mode voltage of the HVF can both be configured via the DPM, allowing for user customization. The DAC input signal can also be configured via the DPM to compensate for system bias. That is, when the system has no acceleration input, the system output should be 0. However, due to process errors, packaging errors, assembly errors, etc., the system output may not be 0. By configuring an appropriate value via the DPM, the system output can be made to be 0. This method is called the zero-bias force compensation method.

[0044] In open-loop mode, the high-voltage feedback drive module HVF and the analog adder SUM module in the feedback branch of the single-axis readout circuit are disabled, and the high-voltage generation circuit CPP is also disabled to save power consumption.

[0045] The Digital Processing Module (DPM) can output data to the parameter configuration circuits of each module via the data buses XRG2A, YRG2A, ZRG2A, and CRG2A to configure the parameters of each circuit module. During circuit design, the range of configurable parameters is generally well-considered, typically covering manufacturing errors, packaging errors, and assembly errors in the MEMS structure. During device calibration, device performance can be achieved simply by adjusting the configured parameters, thereby improving device yield.

[0046] In open-loop mode, if analog signal output is selected, the analog signal will be output through the AMUX output terminal. The accelerometer signal digital quantization module A_ADC will stop working, and the digital processing module DPM will shut down some circuits that are only needed in digital mode to save power. If digital signal output is selected in open-loop mode, the accelerometer signal digital quantization module A_ADC will convert the analog signal into a digital signal, the digital processing system DPS will implement the compensation filtering algorithm, and the signal will be output through the digital interface.

[0047] The output signal of the digital processing module (DPM) can be connected to various system auxiliary modules via the CRG2A bus, including the reference voltage and current generation circuit (REF), the digital power supply voltage and analog voltage generation circuit (LDO), and the high voltage generation circuit (CPP). The parameters of these circuits can be configured. The digital power supply voltage and analog voltage generation circuit (LDO) can be implemented by a linear regulator circuit, and the high voltage generation circuit (CPP) can be implemented by a charge pump circuit.

[0048] The reference voltage and current generation circuit REF generates various voltages and currents that are independent of temperature and power supply voltage; the analog voltage generation circuit LDO generates the digital and analog power supply voltages; the clock generation circuit CLKGEN supplies the system with clocks of various frequencies; the high voltage generation circuit CPP provides high voltage power to the high voltage feedback drive module; and the power-on detection circuit POR detects whether the power supply is functioning correctly. The circuit structures of these modules are existing technology in this field and will not be described in detail here.

[0049] When the system is in digital operating mode, precise control measures such as zero bias temperature coefficient calibration, scale factor temperature coefficient calibration, nonlinear calibration, zero bias compensation, scale factor calibration, and system bandwidth compensation can be implemented through data from the digital processing module DPM (built-in memory). Furthermore, the built-in filter bank can configure the parameters of the low-pass filter, such as bandwidth and speed, through the memory. The digital processing module DPM has a variety of built-in digital communication interfaces, such as I2C, SPI, RS485, and many other digital interfaces, which can be selected through the configurations stored in the memory.

[0050] The high-voltage generation circuit CPP, the high-voltage feedback drive module HVF, and the digital processing module DPM can flexibly configure parameters such as the high-voltage common-mode voltage and system calibration factor output by each high-voltage feedback drive module HVF, and realize individual configuration of the X, Y, and Z axes, thereby meeting the matching requirements of different MEMS accelerometer heads and expanding the adaptation range of MEMS accelerometer heads.

[0051] The voltage signal output by the temperature sensor TS is quantized by the temperature sensor quantization circuit T_ADC and then fed into the digital processing module DPM for temperature compensation.

[0052] The low-pass filter (LPF) and digital processing module (DPM) can be equipped with a system restart scheme for pull-in detection, a system restart scheme for saturation detection, and a system restart scheme for saturation oscillation detection. These features can further improve system reliability and thus increase yield.

[0053] The digital-to-analog converter (DAC), analog adder (SUM), high-voltage feedback drive module (HVF), and digital processing module (DPM) together enable system self-testing; the detection enable can be configured via pins or memory to perform self-testing, facilitating error detection for users.

[0054] The analog multiplication circuit AMUX, digital processing module DPM, and memory can be configured with three axial closed-loop or open-loop modes respectively, which improves the circuit's adaptability and makes it easier for users to use. It can also further improve system reliability and thus increase yield. When the open-loop mode is selected, unused internal circuits can be turned off to save device power consumption.

[0055] The digital processing module has a built-in memory, which can be a one-time programmable memory, a multiple-erasable and rewritable memory, etc.

[0056] The MEMS triaxial closed-loop accelerometer readout circuit described in this invention enables closed-loop control of the accelerometer; analog and digital signal outputs can be achieved for each of the three axes; each axis readout circuit can be individually selected for closed-loop or open-loop control; simultaneously, it integrates internal memory and control circuitry, allowing for flexible configuration of the parameters of the three axis readout circuits and timely adjustment of the accelerometer processing parameters, thereby improving device yield; it is also compatible with both analog and digital signal outputs, making it convenient for users.

[0057] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A closed-loop readout circuit for a triaxial MEMS accelerometer, characterized in that: It includes three single-axis closed-loop readout circuits, which are respectively connected to the X, Y, and Z axes of the triaxial MEMS accelerometer. The output terminals of the three single-axis closed-loop readout circuits are connected to the data input terminal of the accelerometer signal digital quantization module. The output terminal of the accelerometer signal digital quantization module is connected to the input terminal of the digital processing module. The output terminal of the digital processing module digitally outputs the accelerometer signal. The single-axis closed-loop readout circuit includes a capacitor-to-voltage conversion circuit, a low-pass filter, a proportional-integral-differential (PID) controller, a mode control circuit, an accelerometer signal quantization module, and a self-calibration module. The capacitor-to-voltage conversion circuit is connected to the triaxial MEMS accelerometer. The output of the capacitor-to-voltage conversion circuit is connected to the low-pass filter, and the output of the low-pass filter is connected to the PID controller. The output of the PID controller is connected to the mode control circuit. The output of the mode control circuit is connected to the accelerometer signal quantization module. The output of the capacitor-to-voltage conversion circuit is also connected to the self-calibration module.

2. The closed-loop readout circuit for a triaxial MEMS accelerometer according to claim 1, characterized in that: The single-axis closed-loop readout circuit also includes a feedback branch, which consists of a digital-to-analog converter, an analog adder, and a high-voltage feedback circuit. The two inputs of the analog adder are connected to the outputs of the digital-to-analog converter and the proportional-integral-derivative controller, respectively. The output of the analog adder is connected to the high-voltage feedback drive module, and the output of the high-voltage feedback drive module is connected to the force balance input of the accelerometer as a feedback output.

3. The closed-loop readout circuit for a triaxial MEMS accelerometer according to claim 1, characterized in that: The capacitor voltage conversion circuit includes a differential operational amplifier and a demodulator connected to the output of the differential operational amplifier. An amplification feedback capacitor is connected between the input and output of the differential operational amplifier, and a zero-bias compensation capacitor is connected in series between the two inputs of the differential operational amplifier.

4. The closed-loop readout circuit for a triaxial MEMS accelerometer according to claim 1, characterized in that: It also includes a temperature sensor and a temperature signal analog-to-digital converter connected to the temperature sensor, with the output of the temperature signal analog-to-digital converter connected to a digital processing module.

5. The closed-loop readout circuit for a triaxial MEMS accelerometer according to claim 1 or 4, characterized in that: The communication interface of the digital processing module includes one or more of the following: I2C, SPI, and RS485 digital communication interfaces.

6. The closed-loop readout circuit for a triaxial MEMS accelerometer according to claim 1 or 4, characterized in that: The digital processing module includes a memory and a memory control module, wherein the memory is a one-time programmable memory or a multiple-erasable and rewritable memory.

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