Differential capacitive sensor signal reading circuit and frequency response adjusting method thereof

Abstract

The invention relates to a differential capacitive sensor signal reading circuit and a frequency response adjusting method thereof. The reading circuit comprises an alternating current carrier signal generating circuit, a double-arm differential bridge measuring circuit, a signal demodulation circuit and a signal amplification and frequency response adjusting circuit. Wherein the core measurement circuit of the differential capacitance sensor comprises two parallel capacitance arms and is used for converting the displacement amount d sensed by the sensor into an amplitude modulation signal Uo; the differential capacitance sensor is used for converting the capacitance variable quantity of the differential capacitance sensor into an electric signal and ensuring that a linear relation exists between signal output voltage and the capacitance variable quantity. Through the ingenious circuit design, nonlinear errors are effectively reduced, the signal reading precision is improved, the accuracy and stability of output signals of the sensor are ensured, and the sensor is particularly suitable for high-precision measurement and detection application; and the frequency response is improved, and the anti-interference capability is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor signal processing, and in particular to a differential capacitance sensor signal readout circuit and a frequency response adjustment method thereof. Background Art

[0002] With the development of electronic technology, capacitive sensors are widely used as measuring instruments in many fields, such as non-destructive testing, medical testing, automatic control, bioengineering, etc. Capacitive sensors detect changes in capacitance to infer the characteristics of the measured object, such as displacement, pressure, humidity, temperature, magnetic induction intensity, electric field, and oil, etc. When measuring, capacitive sensors are easily affected by external electromagnetic interference, resulting in inaccurate measurement results, because the measurement range of the sensor is generally in the micrometer range.

[0003] In modern sensor technology, capacitive sensors are widely used in various precision measurement and monitoring systems due to their simple structure, sensitive response, and contactless operation, especially in the fields of acoustic wave detection, position sensing, and pressure measurement. The signal readout circuit of a capacitive sensor is one of its core components, and is usually responsible for converting the capacitance changes sensed by the sensor into processable electrical signals. The existing capacitive sensor signal readout circuit has certain limitations in many aspects, which are mainly reflected in the following two aspects:

[0004] 1. Nonlinear error: Existing capacitive sensor signal readout circuits usually produce nonlinear errors, especially during the measurement process, the relationship between capacitance change and signal output is not strictly linear. This affects the measurement accuracy in some application scenarios, making it impossible to achieve accurate signal restoration, resulting in a large deviation in the sensor output signal.

[0005] 2. Insufficient frequency response: The frequency response of traditional capacitive sensor signal readout circuits often cannot meet the requirements of different application scenarios. Especially when detecting wide-band signals, their frequency response often cannot stably cover a larger range of frequencies, resulting in the inability to accurately detect or analyze high-frequency or low-frequency signals.

[0006] See also Figure 4 As shown, in some detection applications, the differential capacitance sensor has large differences in response amplitude in different frequency bands due to structural design limitations, and fails to meet the index requirements within the required frequency range [0.1Hz-200Hz (3dB)]. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a differential capacitance sensor signal readout circuit and a frequency response adjustment method thereof, so as to solve the problems of low signal accuracy and slow frequency response in the prior art.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A differential capacitance sensor signal readout circuit, characterized in that it mainly comprises:

[0010] AC carrier signal generating circuit: generates a stable AC carrier signal with a frequency higher than the frequency band of the measured signal as a driving signal for the differential bridge;

[0011] Double-arm differential bridge measurement circuit: The core measurement circuit of the differential capacitance sensor, which contains two parallel capacitance arms, is used to convert the displacement △d sensed by the sensor into an amplitude modulation signal U o ; Used to convert the capacitance change of the differential capacitance sensor into an electrical signal and ensure that there is a linear relationship between the signal output voltage and the capacitance change;

[0012] Signal demodulation circuit: demodulates the AC signal measured by the double-arm differential bridge through a multiplier and a low-pass filter, filters out the carrier component and obtains a valid signal;

[0013] Signal amplification and frequency response adjustment circuit: It consists of three-stage low-pass filters with gain. It adjusts the frequency response of the output signal through the combination of different cut-off frequency points to achieve response control in a wide frequency range.

[0014] Furthermore, the double-arm differential bridge measurement circuit includes two parallel capacitor arms consisting of a first capacitor C1 and a second capacitor C2, which are used to convert the displacement △d sensed by the sensor into an amplitude modulation signal U o , converting the capacitance change of the differential capacitance sensor into an electrical signal, and ensuring that there is a linear relationship between the signal output voltage and the capacitance change; and also including a first resistor R1 and a second resistor R2; wherein the first capacitor C1 and the second capacitor C2 are two equivalent capacitors of the differential capacitor, C1 and C2 are connected in series, and at the same time are connected in parallel with the two series-connected resistors R1 and R2 to form a double-arm differential bridge measurement circuit;

[0015] Among them, under the condition of R1=R2, the output voltage of the double-arm differential bridge measurement circuit satisfies the following relationship:

[0016]

[0017] At this time, U o It satisfies a strict linear relationship with △d; the measured △d is used as a modulation signal to control the amplitude of the carrier signal E, and the modulated signal U is obtained. o .

[0018] Furthermore, the differential capacitor has the following characteristics:

[0019]

[0020] Therefore, the signal readout circuit is constructed by △U and The linear relationship between them ensures the linear correlation between △U and △d, and improves the accuracy of signal reading.

[0021] Furthermore, the frequency of the AC carrier signal generating circuit is set higher than a specific proportion of the frequency band of the measured signal to reduce signal distortion and improve measurement accuracy.

[0022] Furthermore, the parameters of the first-order low-pass filter, the Sallen-Key low-pass filter and the MFB low-pass filter in the signal amplification and frequency response adjustment circuit can be adjusted independently to adapt to the signal frequency characteristics of different measurement requirements.

[0023] Furthermore, the type and parameters of the low-pass filter can be adjusted according to different application scenarios to optimize the frequency response of the entire signal readout circuit.

[0024] Furthermore, the low-pass filter adopts a three-stage low-pass filter with gain, the first-stage circuit mainly realizes the primary amplification of the signal, the cutoff frequency of the first-order low-pass filter should be slightly higher than the upper limit of the frequency band of the measured signal, the second-stage circuit further amplifies the signal, but the cutoff frequency of the Sallen-Key filter should be set at the middle value of the frequency band of the measured signal, so as to effectively gain the signal in the 0.1-100Hz frequency band, and provide appropriate gain control for the 100-200Hz frequency band, so that the gain of the high-frequency band signal is slightly lower than that of the low-frequency band; the third-stage circuit uses an MFB-type low-pass filter with a frequency response characteristic different from that of the SK filter to further adjust the frequency response characteristics of the output signal; through cooperation with the second-stage cutoff frequency, the final output signal achieves the expected response effect in the entire frequency range, thereby meeting the design index requirements.

[0025] The present invention also provides a frequency response adjustment method for a differential capacitance sensor signal readout circuit, comprising the following steps: converting the capacitance change of the differential capacitance sensor into an electrical signal through a double-arm differential bridge measurement circuit; driving the double-arm differential bridge measurement circuit with an AC carrier signal higher than the frequency band of the measured signal; demodulating the output signal through a signal demodulation circuit composed of a multiplier and a low-pass filter to restore the original signal; amplifying and adjusting the frequency response of the demodulated signal through a signal amplification and frequency response adjustment circuit to ensure that the signal has a stable and adjustable response within the entire frequency band.

[0026] Furthermore, the gain and cut-off frequency of the signal amplification and frequency response adjustment circuit are adjustable, and can adapt to the measurement of different capacitance change rates.

[0027] Furthermore, the frequency adjustable points are:

[0028] Cut-off frequency point 1:

[0029] Cut-off frequency point 2:

[0030] Among them, according to the characteristics of its own signal, according to the SK and MFB frequency response characteristics, R is flexibly adjusted. 16 R 17 C7C8R3R 15 The value size of C5C6.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. Improve signal accuracy: The present invention effectively reduces nonlinear errors and improves the accuracy of signal reading through clever circuit design, ensuring the accuracy and stability of sensor output signals, and is particularly suitable for high-precision measurement and detection applications.

[0033] 2. Improve frequency response: The present invention optimizes the circuit design to ensure stable signal reading performance within a wide frequency range, thereby avoiding signal distortion and attenuation caused by insufficient frequency response.

[0034] 3. Enhanced anti-interference capability: The present invention effectively improves the anti-interference capability, can maintain signal stability in complex electromagnetic environments, reduce the impact of external noise and electromagnetic interference on signal quality, and ensure the reliability and stable operation of the equipment.

[0035] In summary, the present invention improves the frequency response range through optimized design, ensures that signals of different frequencies can be stably processed, enhances the accuracy and reliability of the signal, and thus improves the performance of the differential capacitive sensor in various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a capacitive sensor signal readout circuit diagram of embodiment 1 of the present invention;

[0037] Figure 2 is the double-arm differential bridge measurement circuit diagram in Example 1;

[0038] Figure 3 This is a simplified diagram of a differential capacitance sensor of the present invention;

[0039] Figure 4 This is a situation where the frequency range of the existing differential capacitance sensor is unstable. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. It is usually described and shown in the drawings herein that the components can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments provided in the drawings is not intended to limit the scope of protection claimed, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] like Figure 1 As shown, the present invention provides a differential capacitance sensor signal readout circuit, which mainly has four modules, specifically including:

[0043] AC carrier signal generating circuit: generates a stable AC carrier signal with a frequency higher than the frequency band of the measured signal as a driving signal for the differential bridge;

[0044] Double-arm differential bridge measurement circuit: The core measurement circuit of the differential capacitance sensor, which contains two parallel capacitance arms, is used to convert the displacement △d sensed by the sensor into an amplitude modulation signal U o ;

[0045] Signal demodulation circuit: demodulates the AC signal measured by the double-arm differential bridge through a multiplier and a low-pass filter, filters out the carrier component and obtains a valid signal;

[0046] Signal amplification and frequency response adjustment circuit: It consists of three-stage low-pass filters with gain. It adjusts the frequency response of the output signal through the combination of different cut-off frequency points to achieve response control in a wide frequency range.

[0047] Wherein, the double-arm differential bridge measurement circuit is used to convert the capacitance change of the differential capacitance sensor into an electrical signal, and ensure that there is a linear relationship between the signal output voltage and the capacitance change. This design effectively improves the linearity of the signal, so that the readout circuit can more accurately reflect the slight changes of the capacitance sensor, and is particularly suitable for occasions requiring high-precision measurement, such as displacement detection in industrial automation, vibration analysis of precision instruments, etc. Further, the double-arm differential bridge measurement circuit includes a specific circuit structure and component parameters for improving signal accuracy and anti-interference ability. By optimizing the circuit structure and accurately matching the component parameters, the readout circuit can effectively suppress external noise and improve the signal-to-noise ratio of the signal, and is suitable for environments with severe electromagnetic interference, such as power system monitoring, automotive electronics, etc.

[0048] See also Figure 2 In the double-arm differential bridge measurement circuit, under the condition of R1=R2, the output voltage of the double-arm differential bridge measurement circuit satisfies the following relationship:

[0049]

[0050] At this time, U o It satisfies a strict linear relationship with △d. The measured △d is used as a modulation signal to control the amplitude of the carrier signal E, and the modulated signal U is obtained. o .

[0051] Since the essence of the differential capacitance sensor measurement work is to convert the vibration diaphragm displacement △d triggered by the measured information into the capacitance value change △C, and further convert △C into the voltage change △U (or current change △I) through the back-end signal readout circuit, the measured information can be reversely deduced through ADC acquisition. In view of the intrinsic nonlinear errors of both △d and △C, the signal readout circuit of the present invention avoids the error transmission of the △d→△C→△U derivation process.

[0052] After analysis, the differential capacitor has the following characteristics:

[0053]

[0054] Therefore, the signal readout circuit is constructed by △U and The linear relationship between them ensures the linear correlation between △U and △d, and improves the accuracy of signal reading.

[0055] Based on this, the present invention adopts a double-arm differential bridge measurement circuit as the first-stage readout circuit of the differential capacitance sensor to ensure that U o Maintain a strict linear relationship with △d. Although the existing transformer bridge circuit can also achieve a linear output relationship However, transformers are susceptible to interference in complex electromagnetic field environments, and compared to resistors, transformers are larger in size, which is not conducive to small-size integrated design. In addition, the transformer alternating bridge circuit requires the two secondary winding coils to remain consistent, which is difficult and costly in actual engineering design. In contrast, high-precision resistors in double-arm differential bridge circuits are easier to obtain and have lower costs, making them suitable for high-precision, low-cost integrated design.

[0056] See also Figure 3 , is a simplified diagram of a differential capacitance sensor. Among them, A and C are fixed poles, and B is usually a sensitive vibrating diaphragm. According to the capacitance determination formula of a parallel plate capacitor Then we have:

[0057]

[0058] When the capacitive sensor vibrates and receives disturbances (detection information), then:

[0059]

[0060] exist conditions,

[0061] At this time, △C and △d are only approximately linearly related, and there is a certain nonlinear error.

[0062] The frequency of the generated AC carrier signal should be much higher than the frequency band of the measured signal. After the output signal Sig-AM of the double-arm differential bridge measurement circuit passes through the detection circuit composed of multiplier U7, R13 and C9, the signal demodulation and AC carrier signal filtering have been completed. The signal amplification and frequency response adjustment circuit is composed of a three-stage operational amplifier circuit. The first stage mainly realizes the primary amplification of the signal, and further filters the high-frequency carrier signal through the low-pass filter composed of R7 and C3; the second stage is a Sallen-Key type low-pass filter with gain amplification, and the cut-off frequency point can be set according to actual needs; the third stage is an MFB type low-pass filter with gain amplification, and the frequency response is adjusted by the coordination of different cut-off frequency points between the second and third stages.

[0063] Furthermore, the frequency of the AC carrier signal generating circuit is set higher than a specific ratio of the measured signal frequency band to reduce signal distortion and improve measurement accuracy. This design can avoid mutual interference between the signal frequency and the sensor's natural frequency, and also facilitate the recovery and extraction of the measured signal in the later stage.

[0064] The multiplier in the signal demodulation circuit adopts a specific demodulation algorithm to improve demodulation efficiency and signal quality. The optimized demodulation algorithm can restore the original signal more quickly and accurately, and is suitable for scenarios that require real-time processing, such as fast-response touch panels, real-time monitoring biomedical sensors, etc.

[0065] The parameters of the first-order low-pass filter, the Sallen-Key low-pass filter and the MFB low-pass filter in the signal amplification and frequency response adjustment circuit can be adjusted independently to adapt to the signal frequency characteristics of different measurement requirements. This independent adjustability enables the circuit to accurately match the output characteristics of different sensors, improves the overall adaptability and measurement accuracy of the system, and is suitable for measurement systems that require fine adjustment, such as signal processing of geological exploration equipment, sensor signal readout in the aerospace field, etc.

[0066] Furthermore, the type and parameters of the low-pass filter can be adjusted according to different application scenarios to optimize the frequency response of the entire signal readout circuit. This flexibility enables the circuit to adapt to a wide frequency range from low frequency to high frequency, and is suitable for multi-band signal processing occasions, such as signal processing of audio equipment, signal demodulation of multi-mode communication systems, etc.

[0067] In addition, the present invention adopts a three-stage low-pass filter with gain, the first stage circuit mainly realizes the primary amplification of the signal, the cut-off frequency of the first-order low-pass filter should be slightly higher than the upper limit of the frequency band of the measured signal (such as: 1kHz), the second stage circuit further amplifies the signal, but the cut-off frequency of the Sallen-Key filter should be set at the middle value of the frequency band of the measured signal (such as 100Hz), so as to effectively gain the signal in the 0.1-100Hz frequency band, and provide appropriate gain control for the 100-200Hz frequency band, so that the gain of the high-frequency band signal is slightly lower than that of the low-frequency band. The third stage circuit uses an MFB type low-pass filter with a different frequency response characteristic from the SK filter, and the main purpose is to further adjust the frequency response characteristics of the output signal. Through the cooperation with the second stage cut-off frequency, the final output signal achieves the expected response effect in the entire frequency range, thereby meeting the design index requirements.

[0068] In a specific implementation, the signal amplification and frequency response adjustment circuit of the present invention also includes a control unit for automatically adjusting the gain and cutoff frequency to adapt to the measurement of different capacitance change rates. This automatic adjustment function can optimize the signal processing process in real time, so that the circuit can automatically adjust to the optimal state when facing different measurement conditions, and is particularly suitable for occasions with large environmental changes and requiring rapid response, such as motion detection of smart wearable devices, environmental monitoring of smart home systems, etc.

[0069] The present invention also provides a frequency response adjustment method for a differential capacitance sensor signal readout circuit, comprising the following steps: converting the capacitance change of the differential capacitance sensor into an electrical signal through a double-arm differential bridge measurement circuit; driving the double-arm differential bridge measurement circuit with an AC carrier signal higher than the frequency band of the measured signal; demodulating the output signal through a signal demodulation circuit composed of a multiplier and a low-pass filter to restore the original signal; amplifying and adjusting the frequency response of the demodulated signal through a signal amplification and frequency response adjustment circuit to ensure that the signal has a stable and adjustable response in the entire frequency band. This method not only improves the efficiency of signal processing, but also ensures the stability and reliability of the signal, and is suitable for occasions requiring fast and accurate signal processing, such as high-speed data acquisition systems, real-time control systems, etc.

[0070] In the specific implementation, the gain and cutoff frequency of the signal amplification and frequency response adjustment circuit are automatically adjusted to adapt to the measurement of different capacitance change rates. This automatic adjustment function can optimize the signal processing process in real time, ensuring that the circuit can automatically adjust to the best state when facing different measurement conditions. It is particularly suitable for occasions that require rapid response and adaptation, such as real-time monitoring of automated production lines and dynamic signal processing of intelligent transportation systems.

[0071] The present invention also proposes a capacitive sensor signal reading method, which significantly improves the accuracy, stability and adaptability of capacitive sensor signal processing by adopting a double-arm differential bridge measurement circuit, an AC carrier signal of a specific frequency, an optimized signal demodulation algorithm and an adjustable signal amplification and frequency response adjustment circuit. The method of the present invention can not only effectively reduce signal distortion and improve measurement accuracy, but also automatically adapt to different capacitance change rates and signal frequency characteristics, greatly enhancing the application ability of capacitive sensors in various complex environments. In addition, through the combination of software and hardware, the intelligence and automation of signal processing can also be realized, providing more reliable and efficient signal processing means for multiple fields such as industrial automation, precision measurement, environmental monitoring, medical health, and intelligent transportation, providing a solid technical foundation for realizing smarter, more accurate, and faster signal processing, and is expected to become an important development direction in the field of sensor signal processing in the future.

[0072] The present invention also relates to a computer program product, comprising a computer program, which is implemented when executed by a processor, including the steps of the capacitance sensor signal reading method.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A differential capacitance sensor signal readout circuit, characterized in that: Mainly include: AC carrier signal generating circuit: generates a stable AC carrier signal with a frequency higher than the frequency band of the measured signal as a driving signal for the differential bridge; Double-arm differential bridge measurement circuit: The core measurement circuit of the differential capacitance sensor, which contains two parallel capacitance arms, is used to convert the displacement △d sensed by the sensor into an amplitude modulation signal U o ; Used to convert the capacitance change of the differential capacitance sensor into an electrical signal and ensure that there is a linear relationship between the signal output voltage and the capacitance change; Signal demodulation circuit: demodulates the AC signal measured by the double-arm differential bridge through a multiplier and a low-pass filter, filters out the carrier component and obtains a valid signal; Signal amplification and frequency response adjustment circuit: It consists of three-stage low-pass filters with gain. It adjusts the frequency response of the output signal through the combination of different cut-off frequency points to achieve response control in a wide frequency range.

2. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The double-arm differential bridge measurement circuit includes two parallel capacitor arms consisting of a first capacitor C1 and a second capacitor C2, which are used to convert the displacement △d sensed by the sensor into an amplitude modulation signal U o , converting the capacitance change of the differential capacitance sensor into an electrical signal, and ensuring that there is a linear relationship between the signal output voltage and the capacitance change; and also including a first resistor R1 and a second resistor R2; wherein the first capacitor C1 and the second capacitor C2 are two equivalent capacitors of the differential capacitor, C1 and C2 are connected in series, and at the same time are connected in parallel with the two series-connected resistors R1 and R2 to form a double-arm differential bridge measurement circuit; Among them, under the condition of R1=R2, the output voltage of the double-arm differential bridge measurement circuit satisfies the following relationship: At this time, U o It satisfies a strict linear relationship with △d; the measured △d is used as a modulation signal to control the amplitude of the carrier signal E, and the modulated signal U is obtained. o .

3. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The differential capacitor has the following characteristics: Therefore, the signal readout circuit is constructed by △U and The linear relationship between them ensures the linear correlation between △U and △d, and improves the accuracy of signal reading.

4. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The frequency of the AC carrier signal generating circuit is set higher than a specific proportion of the frequency band of the measured signal to reduce signal distortion and improve measurement accuracy.

5. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The parameters of the first-order low-pass filter, the Sallen-Key low-pass filter and the MFB low-pass filter in the signal amplification and frequency response adjustment circuit can be adjusted independently to adapt to the signal frequency characteristics of different measurement requirements.

6. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The type and parameters of the low-pass filter can be adjusted according to different application scenarios to optimize the frequency response of the entire signal readout circuit.

7. The differential capacitance sensor signal readout circuit according to claim 1, characterized in that: The low-pass filter adopts a three-stage low-pass filter with gain. The first-stage circuit mainly realizes the primary amplification of the signal. The cutoff frequency of the first-order low-pass filter should be slightly higher than the upper limit of the frequency band of the measured signal. The second-stage circuit further amplifies the signal, but the cutoff frequency of the Sallen-Key filter should be set at the middle value of the frequency band of the measured signal, so as to effectively gain the signal in the 0.1-100Hz frequency band, and provide appropriate gain control for the 100-200Hz frequency band, so that the gain of the high-frequency band signal is slightly lower than that of the low-frequency band; the third-stage circuit uses an MFB-type low-pass filter with a frequency response characteristic different from that of the SK filter to further adjust the frequency response characteristics of the output signal; through cooperation with the second-stage cutoff frequency, the final output signal achieves the expected response effect in the entire frequency range, thereby meeting the design index requirements.

8. A method for adjusting the frequency response of a differential capacitance sensor signal readout circuit, characterized in that: The following steps are involved: The capacitance change of the differential capacitance sensor is converted into an electrical signal through a double-arm differential bridge measurement circuit; An AC carrier signal with a frequency higher than the measured signal is used to drive the double-arm differential bridge measurement circuit. The output signal is demodulated by a signal demodulation circuit composed of a multiplier and a low-pass filter to restore the original signal. The demodulated signal is amplified and the frequency response is adjusted by a signal amplification and frequency response adjustment circuit to ensure that the signal has a stable and adjustable response in the entire frequency band.

9. The frequency response adjustment method of the differential capacitance sensor signal readout circuit according to claim 8, characterized in that: The gain and cut-off frequency of the signal amplification and frequency response adjustment circuit are adjustable, and can adapt to the measurement of different capacitance change rates.

10. The frequency response adjustment method of the differential capacitance sensor signal readout circuit according to claim 8, characterized in that: The specific steps include: Cut-off frequency point 1: Cut-off frequency point 2: According to the characteristics of its own signal, according to the frequency response characteristics of SK and MFB, flexibly adjust R 16 R 17 C7 C8 R3R 15 The value size of C5 and C6.

Images