MEMS gyroscope

Abstract

The application provides a MEMS gyroscope, which comprises a MEMS inertial sensing part, a gyroscope interface circuit, wherein the MEMS inertial sensing part comprises a driving capacitor group, a driving detection capacitor group and a detection capacitor group of one or more axes; the gyroscope interface circuit comprises a driving circuit, a detection circuit of one or more axes, a correction capacitor group of one or more axes and a digital processing circuit; the driving circuit comprises a driving charge amplifier, the detection circuit comprises a detection charge amplifier of one or more axes, one end of a first correction capacitor in the correction capacitor group of each axis is connected to a first output end of the driving charge amplifier, the other end is connected to a first input end of the detection charge amplifier of the corresponding axis, one end of a second correction capacitor in the correction capacitor group of each axis is connected to a second output end of the driving charge amplifier, and the other end is connected to a second input end of the detection charge amplifier of the corresponding axis. In this way, the quadrature error can be eliminated, and the gyroscope zero bias stability and noise level are improved.

Description

[0001] The application relates to the technical field of gyroscopes, in particular to a MEMS (Micro-Electro-Mechanical System) gyroscope.

[0002] A gyroscope is an angular velocity sensor based on the Coriolis effect, has the advantages of low power consumption, small size, low cost, easy integration and the like, and is widely applied to the fields of aerospace, automobile electronics, robots and the like.

[0003] The gyroscope interface circuit is realized by using a highly integrated ASIC (Application Specific Integrated Circuit). The ASIC circuit has the advantages of high precision, small size, low cost and strong environmental adaptability, and is easy to meet the practical needs such as batch measurement and adjustment of the MEMS gyroscope, and whether the integration of the MEMS gyroscope interface circuit can be realized becomes a bottleneck restricting the high performance, miniaturization and low cost of the device.

[0004] The gyroscope interface circuit is divided into a driving circuit and a detection circuit. The driving circuit is an important measurement and control circuit in the MEMS gyroscope. It generates a driving signal to control the vibration of the gyroscope mass and stabilize the vibration, and provides a demodulation reference signal for the detection circuit. The stability of the self-excited driving circuit of the silicon gyroscope is one of the difficulties of the driving circuit at present. The amplitude stability and frequency stability caused by the phase noise of the gyroscope driving signal directly affect the angular velocity stability. The traditional analog driving circuit has poor reliability, low precision and performance parameters susceptible to temperature and aging, so that the stability and environmental adaptability of the driving circuit are poor, and the advanced control algorithm is not easy to realize in the analog circuit. The detection circuit is used for reading the output signal of the sensor. The high-precision gyroscope has high requirements for the detection circuit in terms of weak signal detection, noise suppression, error elimination, environmental adaptability and temperature compensation.

[0005] In addition, the silicon micro-gyroscope is manufactured based on the silicon micromachining process. Due to the existence of non-ideal factors such as machining errors, there are other coupling mechanisms between the driving direction and the detection direction, and the most notable one is the elastic coupling, which causes the detection vibration caused by the elastic coupling and the Coriolis effect to be 90 degrees apart in phase, and is therefore called orthogonal error. The orthogonal error directly affects the key performances such as the zero bias stability and the zero bias temperature stability of the gyroscope.

[0006] Therefore, there is an urgent need to propose a new technical solution to solve the above problems.

[0007] ​​​One of the purposes of the present application is to provide a MEMS gyroscope which uses a synchronous compensation method to eliminate quadrature error, thereby improving the gyroscope's zero bias stability and noise level.

[0008] According to one aspect of the present application, the present application provides a MEMS gyroscope, which comprises: a MEMS inertial sensing part comprising: a drive capacitor group, a drive detection capacitor group, and a detection capacitor group of one or more axes; a gyroscope interface circuit comprising: a drive circuit, a detection circuit of one or more axes, a correction capacitor group of one or more axes, and a digital processing circuit; the drive circuit comprises a drive charge amplifier, a first input terminal of the drive charge amplifier is connected to one end of a first drive detection capacitor in the drive detection capacitor group, a second input terminal of the drive charge amplifier is connected to one end of a second drive detection capacitor in the drive detection capacitor group, the detection circuit comprises a detection charge amplifier of one or more axes, a first input terminal of each axis' detection charge amplifier is connected to one end of a first detection capacitor in the detection capacitor group of the corresponding axis, a second input terminal of each axis' detection charge amplifier is connected to one end of a second detection capacitor in the detection capacitor group of the corresponding axis, a first correction capacitor in the correction capacitor group of each axis is connected to a first output terminal of the drive charge amplifier at one end and to a first input terminal of the detection charge amplifier of the corresponding axis at the other end, and a second correction capacitor in the correction capacitor group of each axis is connected to a second output terminal of the drive charge amplifier at one end and to a second input terminal of the detection charge amplifier of the corresponding axis at the other end.

[0009] Compared with the prior art, the present application uses the characteristic that the output current useful signal of the drive charge amplifier (DCSA) in the drive circuit is in the same frequency and in phase, compensates the input current of the detection charge amplifier (SCSA) in the detection circuit, thereby eliminating the quadrature signal which is 90 degrees different from the phase of the useful signal in the detection charge amplifier (SCSA) in the detection circuit, and improving the gyroscope's zero bias stability and noise level. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor. Among them:

[0011] Figure 1 is a structural schematic diagram of the MEMS gyroscope in the present application in one embodiment; DETAILED DESCRIPTION

[0012] In order to make the above objectives, characteristics and advantages of the present application more obvious and comprehensible, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0013] The term "one embodiment" or "an embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the implementation can be included in at least one implementation of the application. The appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. The terms connected, coupled, or in communication, unless otherwise defined, as used herein, mean either a direct or indirect connection or coupling.

[0014] In the present application, unless otherwise specifically stated and limited, the terms "connected", "coupled", "coupling" and the like are to be construed broadly and are not limited to direct connections or coupling. The specific meaning of the above terms in the present application can be understood by those skilled in the art according to the specific circumstances.

[0015] The present application makes use of the characteristic that the output current of the driving charge amplifier (DCSA) in the driving circuit is in phase with the useful signal, and compensates the input current of the sensing charge amplifier (SCSA) in the sensing circuit, thereby eliminating the quadrature signal of the sensing charge amplifier (SCSA) in the sensing circuit which is 90 degrees out of phase with the useful signal, and improving the stability of the gyroscope zero bias and the noise level.

[0016] Figure 1 is a structural schematic diagram of the MEMS gyroscope 100 in one embodiment of the present application. As shown in Figure 1 The MEMS gyroscope 100 includes a MEMS inertial sensing part 110 and a gyroscope interface circuit. The gyroscope interface circuit is a CMOS (Complementary Metal Oxide Semiconductor) circuit. The MEMS inertial sensing part 110 is a sensor device of the MEMS gyroscope 100, and its working principle is to convert the acceleration of the reference frame into the capacitance change of the sensor capacitor.

[0017] As shown in Figure 1 The MEMS inertial sensing part 110 includes a driving capacitor group D_p and D_n, a driving and sensing capacitor group D_sense_p and D_sense_n, and a sensing capacitor group of one or more axes.

[0018] The gyroscope interface circuit includes a driving circuit, a sensing circuit of one or more axes, a correction capacitor group QDAC of one or more axes, and a digital processing circuit 121.

[0019] The driving circuit comprises a driving charge amplifier DSCA, a first input terminal of the driving charge amplifier DSCA is connected to one end of a first driving detection capacitor D_sense_p in the driving detection capacitor group D_sense_p and D_sense_n, and a second input terminal of the driving charge amplifier DSCA is connected to one end of a second driving detection capacitor D_sense_n in the driving detection capacitor group D_sense_p and D_sense_n. The detection circuit comprises one or more shafts of detection charge amplifiers SCSA, a first input terminal of each shaft of detection charge amplifier SCSA is connected to one end of a first detection capacitor in the corresponding shaft of detection capacitor group, and a second input terminal of each shaft of detection charge amplifier is connected to one end of a second detection capacitor in the corresponding shaft of detection capacitor group. One end of a first correction capacitor in the correction capacitor group QDAC of each shaft is connected to a first output terminal of the driving charge amplifier DCSA, and the other end is connected to a first input terminal of the corresponding shaft of detection charge amplifier SCSA. One end of a second correction capacitor in the correction capacitor group QDAC of each shaft is connected to a second output terminal of the driving charge amplifier DCSA, and the other end is connected to a second input terminal of the corresponding shaft of detection charge amplifier SCSA.

[0020] Specifically, the MEMS inertial sensing part 110 has three-axis detection capacitor groups, which are x-axis detection capacitor groups sense_x_p and sense_x_n, y-axis detection capacitor groups sense_y_p and sense_y_n, and z-axis detection capacitor groups sense_z_p and sense_x_n. The gyro interface circuit includes three-axis detection circuits and three-axis correction capacitor groups. The three-axis detection circuits are x-axis detection circuit, y-axis detection circuit and z-axis detection circuit, and the three-axis correction capacitor groups are x-axis correction capacitor group QDAC_x, y-axis correction capacitor group QDAC_y and z-axis correction capacitor group QDAC_z. One end of the first correction capacitor in the x-axis correction capacitor group QDAC_x is connected to the first output end of the driving charge amplifier DCSA, and the other end is connected to the first input end of the x-axis detection charge amplifier SCSA_x. One end of the second correction capacitor in the x-axis correction capacitor group QDAC_x is connected to the second output end of the driving charge amplifier DCSA, and the other end is connected to the second input end of the x-axis detection charge amplifier SCSA_x. One end of the first correction capacitor in the y-axis correction capacitor group QDAC_y is connected to the first output end of the driving charge amplifier DCSA, and the other end is connected to the first input end of the y-axis detection charge amplifier SCSA_y. One end of the second correction capacitor in the y-axis correction capacitor group QDAC_y is connected to the second output end of the driving charge amplifier DCSA, and the other end is connected to the second input end of the y-axis detection charge amplifier SCSA_y. One end of the first correction capacitor in the z-axis correction capacitor group QDAC_z is connected to the first output end of the driving charge amplifier DCSA, and the other end is connected to the first input end of the z-axis detection charge amplifier SCSA_z. One end of the second correction capacitor in the z-axis correction capacitor group QDAC_z is connected to the second output end of the driving charge amplifier DCSA, and the other end is connected to the second input end of the z-axis detection charge amplifier SCSA_z.

[0021] In one embodiment, the MEMS inertial sensing part 110 can also be provided with one-axis or two-axis detection capacitor groups, and the gyro interface circuit can also be provided with one-axis or two-axis detection circuits and one-axis or two-axis correction capacitor groups.

[0022] As Figure 1As shown, the detection circuit of each axis further comprises detection mixers mixer_x, mixer_y and mixer_z and detection analog-to-digital converters SADC_x, SADC_y and SADC_z. The digital processing circuit 121 comprises a low-pass filter (LPF) 1211 or a band-pass filter. Two inputs of the detection mixers mixer_x, mixer_y and mixer_z of each axis are connected to two outputs of the detection charge amplifiers SCSA_x, SCSA_y and SCSA_z of the corresponding axis, two outputs of the detection mixers mixer_x, mixer_y and mixer_z of each axis are connected to two inputs of the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of the corresponding axis, and an output of the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis is connected to the low-pass filter 1211 or the band-pass filter of the digital processing circuit 121. The digital processing circuit 121 provides a detection mixing clock signal sen_mix_clk to the detection mixers mixer_x, mixer_y and mixer_z, and the detection mixing clock signal sen_mix_clk is the same frequency and in-phase as the driving clock signal clk_gyro provided to the driving mixer d_mixer. The low-pass filter 1211 or the band-pass filter performs low-pass filtering or band-pass filtering on the digital detection signals BS_SADC_x, BS_SADC_y and BS_SADC_z output by the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis.

[0023] As shown in FIG. 1, the MEMS gyroscope further comprises a digital processing circuit 121. The digital processing circuit 121 is connected to the detection mixers mixer_x, mixer_y and mixer_z of each axis and the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis. The digital processing circuit 121 provides a detection mixing clock signal sen_mix_clk to the detection mixers mixer_x, mixer_y and mixer_z of each axis, and the detection mixing clock signal sen_mix_clk is the same frequency and in-phase as the driving clock signal clk_gyro provided to the driving mixer d_mixer. The digital processing circuit 121 performs low-pass filtering or band-pass filtering on the digital detection signals BS_SADC_x, BS_SADC_y and BS_SADC_z output by the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis. Figure 1 As shown, the MEMS gyroscope further comprises a power supply circuit 130. An output of the power supply circuit 130 is connected to the other end of each capacitor in the driving capacitor group, the driving detection capacitor group and the detection capacitor group. The power supply circuit 130 provides a voltage to the other end of each capacitor in the driving capacitor group, the driving detection capacitor group and the detection capacitor group.

[0024] As shown in FIG. 1, the MEMS gyroscope further comprises a digital processing circuit 121. The digital processing circuit 121 is connected to the detection mixers mixer_x, mixer_y and mixer_z of each axis and the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis. The digital processing circuit 121 provides a detection mixing clock signal sen_mix_clk to the detection mixers mixer_x, mixer_y and mixer_z of each axis, and the detection mixing clock signal sen_mix_clk is the same frequency and in-phase as the driving clock signal clk_gyro provided to the driving mixer d_mixer. The digital processing circuit 121 performs low-pass filtering or band-pass filtering on the digital detection signals BS_SADC_x, BS_SADC_y and BS_SADC_z output by the detection analog-to-digital converters SADC_x, SADC_y and SADC_z of each axis. Figure 1 As shown in FIG. 1, the driving circuit further comprises a comparator Comp, a phase-locked loop PLL, a driving analog-to-digital converter DADC, an automatic gain control digital-to-analog converter AGC_DAC and a driving mixer d_mixer.

[0025] The digital processing circuit 121 comprises an automatic gain control module (AGC) 1212.

[0026] The first input terminal of the comparator Comp is connected with the first output terminal of the drive charge amplifier DSCA, the second input terminal of the comparator Comp is connected with the second output terminal of the drive charge amplifier DSCA, the reference input terminal ref_pll of the phase-locked loop PLL is connected with the output terminal of the comparator Comp, the comparator Comp provides a reference clock for the phase-locked loop PLL, and the output terminal of the phase-locked loop PLL is connected with the digital processing circuit 121. The phase-locked loop PLL generates a phase-locked loop clock pll_clk based on the reference clock.

[0027] The digital processing circuit 121 generates a feedback clock pll_fb_clk which is the same frequency and in phase with the reference clock based on the phase-locked loop clock pll_clk, and provides the feedback clock pll_fb_clk to the feedback input terminal fb_pll of the phase-locked loop PLL, and the digital processing circuit 121 provides the feedback clock pll_fb_clk which is phase-shifted by-90 degrees as a drive clock signal clk_gyro to the drive clock port of the drive mixer d_mixer.

[0028] The two input terminals of the drive analog-digital converter DADCC are connected with the first output terminal and the second output terminal of the drive charge amplifier DSCA respectively, so as to convert the voltage signal output by the drive charge amplifier DSCA into a digital voltage signal, the automatic gain control module AGC performs low-pass filtering on the digital voltage signal through the drive low-pass filter DLPF, and then outputs a digital gain control signal DAC_da which controls the drive amplitude through the PID controller, the digital gain control signal DAC_da is converted into an analog gain control signal by the automatic gain control digital-analog converter AGC_DAC, and the analog gain control signal is provided to the drive mixer d_mixer.

[0029] The drive mixer d_mixer generates a drive signal according to the drive clock signal and the analog gain control signal to drive the mass corresponding to the drive capacitor group D_p and D_n to do simple harmonic motion. Due to the simple harmonic motion of the mass, the capacitance of the drive detection capacitor group D_sense_p and D_sense_n changes.

[0030] The charge transfer caused by the change of the drive sense capacitor group D_sense_p and D_sense_n is sensed and amplified by the drive charge amplifier DCSA and converted into a voltage signal. The output of the drive charge amplifier DCSA is converted into a square wave signal by the comparator Comp, and the square wave signal of the comparator Comp flips at the zero-crossing point of the output of the drive charge amplifier DCSA. The output of the comparator Comp is taken as the reference clock of the phase-locked loop PLL, and the frequency multiplication high-frequency clock of the reference clock is output as the phase-locked loop clock pll_clk. The digital processing circuit 121 generates a feedback clock pll_fb_clk which is the same frequency and in phase with the reference clock by frequency division based on the phase-locked loop clock pll_clk. The phase-locked loop PLL loop can realize the self-excitation start of the MEMS gyroscope and lock the vibration frequency driven by the MEMS near the driven resonance frequency, thereby ensuring the stable operation of the gyroscope.

[0031] The first connection end of the drive mixer d_mixer is connected to one end of the first drive capacitor D_p in the drive capacitor group, and the second connection end of the drive mixer d_mixer is connected to one end of the second drive capacitor D_n in the drive capacitor group.

[0032] When the drive mass makes a simple harmonic motion in a certain direction, if the reference system in which it is located has an acceleration not parallel to the direction of the simple harmonic motion, the mass will also be subjected to a Coriolis force perpendicular to the acceleration and the plane of the driven simple harmonic motion, and the phase of the Coriolis force is 90 degrees different from the driven displacement. The Coriolis force causes the mass to simultaneously make a simple harmonic motion (induced motion due to acceleration) in the perpendicular direction. The induced motion causes the capacitance of the sense capacitor group Sense_p / Sense_n on the axis to change. The charge transfer caused by the change of the capacitance is sensed and amplified by the sense charge amplifier SCSA and converted into a voltage signal. Then the voltage signal is demodulated by the sense mixing clock signal sen_mix_clk mentioned above which is -90 degrees different from fb_pll, leaving a low-frequency acceleration voltage signal. The low-frequency voltage signal is detected by the SADC of the axis and converted into a digital signal, and after LPF filtering in the digital processing circuit 121, becomes the final output of the inertial sensing of the gyroscope.

[0033] In addition, due to the existence of non-ideal factors such as processing errors, there are other coupling mechanisms between the motion of the driving direction and the detection direction, which cause the detection vibration to be 90 degrees out of phase with the detection vibration caused by the Coriolis effect. Due to the difference in design parameters of MEMS driving and sensing, the quadrature error is often much larger than the amplitude of the acceleration signal to be detected, which can cause SCSA_x / y / z to be saturated. SCSA saturation can cause the true acceleration to be unable to be measured. In order to eliminate the signal coupled from the driving direction to the detection direction, the orthogonal error correction capacitor group QDAC_x / y / z (orthogonal error correction capacitor group of x / y / z axis) is needed in the application to introduce the current signal in phase with the driving signal to SCSA_x / y / z to eliminate the orthogonal error coupled from the MEMS driving.

[0034] In the application, the digital driving closed-loop circuit can make the gyroscope quickly start to vibrate and effectively improve the control accuracy, stability, environmental adaptability and other performances. The detection circuit has high performance in amplifying and detecting weak signals, noise suppression, environmental adaptability and temperature compensation. The orthogonal error compensation circuit effectively eliminates the orthogonal error in the useful signal, greatly avoids the saturation of SCSA. Further, the orthogonal error compensation reduces the noise level of the coupling noise caused by the large amplitude of the orthogonal error and clock jitter. The detection circuit plus the orthogonal error compensation ensures the accuracy of the gyroscope output signal measurement.

[0035] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0036] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications and variations to the above embodiments within the scope of the present application.

Claims

1. A MEMS gyroscope, characterized in that, It includes: The MEMS inertial sensing component includes: a drive capacitor bank, a drive detection capacitor bank, and a detection capacitor bank for one or more axes. The gyroscope interface circuit includes: a drive circuit, a detection circuit for one or more axes, a correction capacitor bank for one or more axes, and a digital processing circuit. The driving circuit includes a driving charge amplifier, the first input terminal of which is connected to one end of a first driving detection capacitor in the driving detection capacitor group, and the second input terminal of which is connected to one end of a second driving detection capacitor in the driving detection capacitor group. The detection circuit includes one or more axis-specific charge amplifiers. The first input terminal of the charge amplifier for each axis is connected to one end of the first detection capacitor in the corresponding axis's detection capacitor bank, and the second input terminal of the charge amplifier for each axis is connected to one end of the second detection capacitor in the corresponding axis's detection capacitor bank. One end of the first correction capacitor in the correction capacitor group of each axis is connected to the first output terminal of the driving charge amplifier, and the other end is connected to the first input terminal of the detection charge amplifier of the corresponding axis. One end of the second correction capacitor in the correction capacitor group of each axis is connected to the second output terminal of the driving charge amplifier, and the other end is connected to the second input terminal of the detection charge amplifier of the corresponding axis.

2. The MEMS gyroscope according to claim 1, characterized in that, The MEMS inertial sensing section has three sets of detection capacitors for the x-axis, y-axis, and z-axis. The gyroscope interface circuit includes detection circuits for three axes and calibration capacitor banks for three axes. The detection circuits for the three axes are x-axis, y-axis, and z-axis, respectively. One end of the first correction capacitor in the x-axis correction capacitor bank is connected to the first output terminal of the driving charge amplifier, and the other end is connected to the first input terminal of the x-axis detection charge amplifier. One end of the second correction capacitor in the x-axis correction capacitor bank is connected to the second output terminal of the driving charge amplifier, and the other end is connected to the second input terminal of the x-axis detection charge amplifier. One end of the first correction capacitor in the y-axis correction capacitor bank is connected to the first output terminal of the driving charge amplifier, and the other end is connected to the first input terminal of the y-axis detection charge amplifier. One end of the second correction capacitor in the y-axis correction capacitor bank is connected to the second output terminal of the driving charge amplifier, and the other end is connected to the second input terminal of the y-axis detection charge amplifier. One end of the first correction capacitor in the z-axis correction capacitor group is connected to the first output terminal of the driving charge amplifier, and the other end is connected to the first input terminal of the z-axis detection charge amplifier. One end of the second correction capacitor in the z-axis correction capacitor group is connected to the second output terminal of the driving charge amplifier, and the other end is connected to the second input terminal of the z-axis detection charge amplifier.

3. The MEMS gyroscope according to claim 1, characterized in that, The detection circuit for each axis also includes a detection mixer and a detection analog-to-digital converter. The digital processing circuit includes a low-pass filter or a band-pass filter. The two inputs of the detection mixer for each axis are connected to the two outputs of the corresponding axis's detection charge amplifier. The two outputs of the detection mixer for each axis are connected to the two inputs of the corresponding axis's detection analog-to-digital converter (ADC). The output of the detection ADC for each axis is connected to a low-pass or band-pass filter of the digital processing circuit. The digital processing circuit provides a detection mixing clock signal to the detection mixer, and this detection mixing clock signal is in phase and frequency with the driving clock signal provided to the driving mixer. The low-pass filter or the band-pass filter performs low-pass filtering or band-pass filtering on the digital detection signal output by the analog-to-digital converter for each axis.

4. The MEMS gyroscope according to claim 1, characterized in that, It also includes: The power supply circuit has its output terminal connected to the other end of each capacitor in the driving capacitor group, the driving detection capacitor group, and the detection capacitor group.

5. The MEMS gyroscope according to claim 1, characterized in that, The driving circuit also includes a comparator, a phase-locked loop, a driving analog-to-digital converter, an automatic gain control digital-to-analog converter, and a driving mixer. The digital processing circuit includes an automatic gain control module. The first input terminal of the comparator is connected to the first output terminal of the driving charge amplifier, the second input terminal of the comparator is connected to the second output terminal of the driving charge amplifier, the reference input terminal of the phase-locked loop (PLL) is connected to the output terminal of the comparator, the comparator provides a reference clock to the PLL, and the output terminal of the PLL is connected to the digital processing circuit. The digital processing circuit generates a feedback clock that is in phase and frequency with the reference clock based on the phase-locked loop clock, and provides the feedback clock to the feedback input terminal of the phase-locked loop. The digital processing circuit then shifts the feedback clock by -90 degrees and provides it as a drive clock signal to the drive mixer through the drive clock port. The two input terminals of the driving analog-to-digital converter are respectively connected to the first and second output terminals of the driving charge amplifier to convert the voltage signal output by the driving charge amplifier into a digital voltage signal. The automatic gain control module performs low-pass filtering on the digital voltage signal, and then provides a digital gain control signal to control the driving amplitude through a PID controller. This digital gain control signal is converted into an analog gain control signal by the automatic gain control digital-to-analog converter and provided to the driving mixer. The drive mixer generates a drive signal based on the drive clock signal and the analog gain control signal to drive the mass block corresponding to the drive capacitor bank to perform simple harmonic motion. The first connection terminal of the driving mixer is connected to one end of the first driving capacitor in the driving capacitor group, and the second connection terminal of the driving mixer is connected to one end of the second driving capacitor in the driving capacitor group.

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