Feedback circuit for improving measurement accuracy of strain sensor

Abstract

The invention relates to a feedback circuit for improving the measurement accuracy of a strain sensor, which comprises a power supply circuit, an operational amplifier chip and a filter circuit, the power supply circuit is electrically connected with the operational amplifier chip and supplies power to the operational amplifier chip, the input end of the filter circuit is electrically connected with the operational amplifier chip, and the output end of the filter circuit is suitable for being connected with the reference voltage electric end of an AD chip. A filter circuit is additionally arranged between an operational amplifier and an AD chip, the problem of unstable data caused by overshoot is solved, the filter circuit comprising a resistor and a switching diode is additionally arranged between the operational amplifier chip and the AD chip, and when a feedback signal of a sensor generates tiny change due to external tiny strain, the filter circuit is switched on and switched off. The operational amplifier chip can amplify the signal to an amplitude range which is easier to be processed by a subsequent circuit, meanwhile, the linearity of the signal is ensured, measurement errors caused by distortion in the signal amplification process can be avoided, and therefore the measurement accuracy is improved.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a feedback circuit for improving the measurement accuracy of a strain sensor. Background Art

[0002] The measurement principle of the strain sensor is based on the Wheatstone bridge, which is characterized by a very small output voltage. Under a 10V bridge supply, the bridge output is only about 20mV. The sensor needs to be connected to the instrument through a cable to obtain measurement data. Since the core wire of the cable itself is made of copper wire, and the resistance temperature coefficient of copper is about 0.004 / ℃, the cable will affect the output sensitivity of the sensor due to its own resistance, and ultimately affect the measurement accuracy of the measurement system. In general, in order to improve the measurement accuracy, two feedback terminals are added to the bridge supply end. When the sensor bridge supply voltage changes due to the change of the wire resistance, the voltage at the feedback end also changes. The two feedback lines are directly connected to the feedback end of the AD. The input signal voltage of the AD and the reference voltage have the same bridge supply voltage change, thus eliminating the sensitivity change caused by the wire resistance. However, directly adding two feedback lines to the bridge supply end will result in a large data drift and a large data jump, making it impossible to achieve high-precision measurement. Summary of the invention

[0003] In view of this, the present application proposes a feedback circuit for improving the measurement accuracy of a strain sensor.

[0004] According to one aspect of the present application, a feedback circuit for improving the measurement accuracy of a strain sensor is provided, comprising: Power supply circuit, operational amplifier chip and filter circuit; The power supply circuit is electrically connected to the operational amplifier chip to supply power to the operational amplifier chip; The input end of the filter circuit is connected to the electrical end of the operational amplifier chip, and the output end is suitable for being electrically connected to the reference voltage of the AD chip to avoid overshoot.

[0005] In a possible implementation, pin 1 and pin 3 of the operational amplifier chip are suitable for being electrically connected to a feedback terminal of the sensor.

[0006] In a possible implementation, a resistor R9 and a resistor R12 are also included; Pins 4 and 5 of the operational amplifier chip are short-circuited, electrically connected to the R9 resistor and the R12 resistor, and participate in signal regulation.

[0007] In a possible implementation, the R13 resistor and the R9 resistor are short-circuited and electrically connected to the negative terminal of the reference voltage of the AD chip for signal processing.

[0008] In a possible implementation, it also includes: a resistor R10 and a resistor R8; The 7th pin and the 8th pin of the operational amplifier chip are short-circuited and electrically connected to the R10 resistor and the R8 resistor to process and transmit the signal.

[0009] In a possible implementation, the R10 resistor is electrically connected to the R11 resistor, and the R8 resistor is short-circuited with the R11 resistor and electrically connected to the positive terminal of the reference voltage of the AD chip to ensure circuit function.

[0010] In a possible implementation, it also includes: a resistor R13, a diode D7, a diode D6, a diode D5 and a diode D4; The R12 resistor is electrically connected to the R13 resistor and the cathode of the D7 diode, the anode of the D7 diode is electrically connected to the cathode of the D6 diode, the anode of the D6 diode is electrically connected to the cathode of the D5 diode, the anode of the D5 diode is electrically connected to the cathode of the D4 diode, and the anode of the D4 diode is electrically connected to the R10 resistor and the R11 resistor, respectively.

[0011] In a possible implementation, the power supply circuit includes: a power management chip, a capacitor C5 and a diode D3; Pin 2 of the power management chip is electrically connected to the negative electrode of the C5 capacitor, the positive electrode of the C5 capacitor is electrically connected to the positive electrode of the D3 diode, and the negative electrode of the D3 diode is electrically connected to pin 6 of the power management chip.

[0012] In a possible implementation, the device further includes: a capacitor C7; The positive electrode of the D3 diode is electrically connected to the negative electrode of the C7 capacitor, and the positive electrode of the C7 capacitor is electrically connected to pin 2 of the operational amplifier chip.

[0013] In a possible implementation, it further includes: a D2 diode; The 8 pins of the power management chip are suitable for being electrically connected to a power source, and are electrically connected to the operational amplifier chip through the D2 diode and the D3 diode.

[0014] The beneficial effects of the feedback circuit for improving the measurement accuracy of the strain sensor of the embodiment of the present application are as follows: In order to solve the matching problem between the feedback circuit and the AD chip, a feedback voltage follower is used in the feedback circuit, and there is almost no voltage drop, attenuation or distortion between the input voltage and the output voltage, ensuring that the output voltage is consistent with the input voltage. In order to prevent the output voltage of the op amp from rising when the AD sampling is nearly completed, but the output voltage conversion rate of the op amp is limited and cannot be corrected in time, causing overshoot, a filter circuit is added between the op amp and the AD to solve the data instability caused by overshoot. Specifically, a filter circuit composed of a resistor and a switching diode is added between the op amp chip and the AD chip. When the sensor feedback signal changes slightly due to a slight external strain, the op amp chip can amplify it to an amplitude range that is easier for subsequent circuits to process, while ensuring the linearity of the signal, which helps to avoid measurement errors caused by distortion during signal amplification, thereby improving measurement accuracy.

[0015] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present application and, together with the description, serve to explain the principles of the present application.

[0017] Figure 1 A schematic diagram showing a feedback circuit for improving the measurement accuracy of a strain sensor according to an embodiment of the present application; Figure 2 A circuit diagram of a power module according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0019] Among them, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention or simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0020] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0021] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0022] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0023] like Figure 1 and Figure 2 As shown, the feedback circuit for improving the measurement accuracy of the strain type sensor in the embodiment of the present application includes: a power supply circuit, an operational amplifier chip 10 and a filtering circuit. The power supply circuit is electrically connected to the operational amplifier chip 10 to supply power to the operational amplifier chip 10. The input end of the filtering circuit is electrically connected to the operational amplifier chip 10, and the output end is suitable for connection to the reference voltage terminal of the AD chip to avoid overshoot.

[0024] In this specific embodiment, in order to solve the matching problem between the feedback circuit and the AD chip, a feedback voltage follower is used in the feedback circuit. There is almost no voltage drop, attenuation or distortion between the input voltage and the output voltage, ensuring that the output voltage is consistent with the input voltage. In order to prevent the output voltage of the op amp from rising when the AD sampling is almost completed, but the output voltage conversion rate of the op amp is limited and cannot be corrected in time, causing overshoot, a filter circuit is added between the op amp and the AD to solve the data instability caused by overshoot. Specifically, a filter circuit composed of a resistor and a switching diode is added between the op amp chip 10 and the AD chip. When the sensor feedback signal changes slightly due to a slight external strain, the op amp chip 10 can amplify it to an amplitude range that is easier for subsequent circuits to process, while ensuring the linearity of the signal, which helps to avoid measurement errors caused by distortion during signal amplification, thereby improving measurement accuracy.

[0025] In a specific embodiment, pins 1 and 3 of the operational amplifier chip 10 are suitable for being electrically connected to the feedback end of the sensor. Pins 1 and 3 of the operational amplifier chip 10 are specially designed to establish an electrical connection with the feedback end of the sensor, and can effectively transmit the signal fed back by the sensor to the operational amplifier chip 10. As a front-end device for measuring strain, these signals of the sensor are often relatively weak and need to be subsequently processed and amplified by the operational amplifier chip 10. By connecting pins 1 and 3 of the operational amplifier chip 10 to the feedback end of the sensor, the foundation is laid for the subsequent signal processing process.

[0026] In a specific embodiment, it also includes R9 resistor 15 and R12 resistor 14, and the 4-pin and 5-pin of the operational amplifier chip 10 are short-circuited, and are electrically connected to R9 resistor 15R9 and R12 resistor 14, and participate in signal adjustment, and participate in the signal adjustment process together, which helps to optimize the stability and accuracy of the signal. Specifically, the 4-pin and 5-pin of the operational amplifier chip 10 are short-circuited, and they are electrically connected to R9 resistor 15 and R12 resistor 14, so as to participate in signal adjustment, and signal adjustment is realized by the voltage division and current limiting characteristics of the resistor. When the signal is output from the 4-pin and 5-pin of the operational amplifier chip 10, it will pass through the resistor network formed by R9 resistor 15 and R12 resistor 14. Among them, different resistance values ​​will affect the current and voltage passing through them, thereby adjusting the signal. For example, assuming that the signal is a voltage signal, when passing through R9 and R12 resistor 14, the voltage will be distributed according to the ratio of the resistor, so that the amplitude, phase and other characteristics of the output signal are adjusted.

[0027] In a specific embodiment, it also includes: R13 resistor 16, D7 diode 20, D6 diode 19, D5 diode 18 and D4 diode 17, R12 resistor 14 is electrically connected to the cathode of R13 resistor 16 and D7 diode 20, the anode of D7 diode 20 is electrically connected to the cathode of D6 diode 19, the anode of D6 diode 19 is electrically connected to the cathode of D5 diode 18, the anode of D5 diode 18 is electrically connected to the cathode of D4 diode 17, and the anode of D4 diode 17 is electrically connected to R10 resistor 12 and R11 resistor 13 respectively, which helps to improve the stability and response speed of the circuit. Specifically, the series or parallel combination of R13 resistor 16 and R12 resistor 14 further adjusts the characteristics of the signal. R13 resistor 16 and R12 resistor 14 can change the attenuation degree or voltage division ratio of the signal, and make more precise adjustments to the signal, while the addition of D7 diode 20 introduces a nonlinear element. The diode has unidirectional conductivity. When it is forward-conducting, its conduction voltage is relatively stable. When the signal passes through the D7 diode 20, its cathode will limit the voltage range of the signal. For the forward signal, it will clamp the signal according to its own conduction voltage to prevent the amplitude of the signal from exceeding a certain range, thus protecting the subsequent circuits. For the reverse signal, due to the reverse cutoff characteristics of the diode, it will prevent the reverse signal from passing through to avoid interference with the circuit, thereby ensuring the stability of the circuit and the forward transmission of the signal, while also avoiding possible signal distortion and interference, ensuring that the performance of the circuit meets expectations.

[0028] Among them, the positive electrode of the D7 diode 20 is connected to the negative electrode of the D6 diode 19, forming a series connection mode, and the positive electrode of the D6 diode 19 is connected to the negative electrode of the D5 diode 18, and the positive electrode of the D5 diode 18 is connected to the negative electrode of the D4 diode 17. This connection mode continues the series circuit structure. Finally, the positive electrode of the D4 diode 17 is connected to the R10 resistor 12 and the R11 resistor 13, respectively, to form a branch circuit structure. The current can flow from the positive electrode of the D4 diode 17 to the R10 resistor 12 and the R11 resistor 13. Specifically, from the R12 resistor 14 to the positive electrode of the D4 diode 17, the voltage will gradually decrease, forming a voltage divider circuit for adjusting or stabilizing the voltage of a certain circuit node. In the feedback circuit, such a diode chain can be used as a nonlinear element to provide a form of nonlinear feedback for changing the gain, stability or frequency response of the circuit. When the input voltage is too high, a diode in the diode chain may first break down and conduct a large amount of current, thereby protecting other more sensitive components from damage.

[0029] In a specific embodiment, R13 resistor 16R9 resistor 15 is short-circuited and electrically connected to the negative end of the reference voltage of the AD chip for signal processing. The operational amplifier chip 10 can work in conjunction with the AD chip to jointly complete the task of processing the signal. Specifically, the processed signal is transmitted to the negative end of the reference voltage of the AD chip. When the signal reaches the negative end of the reference voltage of the AD chip, it will provide an important reference benchmark for the conversion process of the AD chip. It provides an accurate reference for the conversion of the AD chip, which helps to improve the conversion accuracy of the AD chip. For example, during the AD conversion process, the signal at the negative end of the reference voltage is compared with the input analog signal. The accurate reference voltage can enable the AD chip to convert the analog signal into a digital signal more accurately, thereby improving the measurement accuracy of the entire measurement system.

[0030] In a specific embodiment, it also includes: R10 resistor 12 and R8 resistor 11, the 7-pin and 8-pin pins of the operational amplifier chip 10 are short-circuited, and are electrically connected to the R10 resistor 12 and the R8 resistor 11 to process and transmit the signal, thereby ensuring the integrity of the circuit function and enabling the entire circuit to work normally. Specifically, the R10 and R8 resistors 11 further process the signal output from the operational amplifier chip 10 by voltage division and current limiting of the signal, so as to better cooperate with other circuit elements. At the same time, through this electrical connection, the signal can be effectively transmitted to the subsequent circuit part, ensuring the normal flow of the signal in the circuit and the continuity of the processing flow.

[0031] In a specific embodiment, the R10 resistor 12 is electrically connected to the R11 resistor 13, and the R8 resistor 11 is short-circuited to the R11 resistor 13 and electrically connected to the positive terminal of the reference voltage of the AD chip to ensure the circuit function.

[0032] In a specific embodiment, the power supply circuit includes: a power management chip 21, a C5 capacitor and a D3 diode 24, the 2 pin of the power management chip 21 is electrically connected to the negative electrode of the C5 capacitor, the positive electrode of the C5 capacitor is electrically connected to the positive electrode of the D3 diode 24, and the negative electrode of the D3 diode 24 is electrically connected to the 6 pin of the power management chip 21, forming a stable power supply circuit to provide reliable power support for the operational amplifier chip 10. Specifically, through such a connection, a carefully processed signal is provided to the positive end of the reference voltage of the AD chip. Similar to the negative end of the reference voltage, the signal at the positive end of the reference voltage is also a key reference in the AD conversion process, and its stability and accuracy are crucial to the result of the AD conversion. The combination of R10, R11 and R8 resistor 11 makes the final adjustment and optimization of the signal, ensuring that the signal input to the positive end of the reference voltage of the AD chip is accurate and stable.

[0033] Among them, the power management chip 21 is responsible for providing the required power for the entire circuit. When the power management chip 21 outputs power, its output may have certain ripples and noise. The C5 capacitor can store and release charges through the charging and discharging process, smooth the power supply voltage, and reduce voltage fluctuations. The D3 diode 24 has multiple functions here. On the one hand, it can prevent the reverse voltage of the power supply from damaging the power management chip 21 or other circuit components, and use its unidirectional conductivity to ensure that the current can only flow in the forward direction; on the other hand, it can also clamp the power supply voltage to a certain extent to protect the circuit from the impact of excessive voltage.

[0034] In a specific embodiment, it also includes: C7 capacitor 25 and D2 diode 23, the positive electrode of D3 diode 24 is electrically connected to the negative electrode of C7 capacitor 25, the positive electrode of C7 capacitor 25 is electrically connected to pin 2 of operational amplifier chip 10, and pin 8 of power management chip 21 is suitable for being electrically connected to the power supply, and is electrically connected to the operational amplifier chip through D2 diode 23 and D3 diode 24, so that the power supply circuit is more stable and reliable, providing a strong guarantee for the normal operation of the entire system.

[0035] Among them, the C7 capacitor 25 further enhances the filtering effect of the power supply, especially for the power input of the 2 pin of the operational amplifier chip 10. By filtering the power input again, it can provide a more stable power supply for the operational amplifier chip 10, reduce the influence of power supply noise on the operation of the operational amplifier chip 10, and the existence of the C7 capacitor 25 helps to ensure that the operational amplifier chip 10 works in a stable power supply environment, avoids signal processing errors or performance degradation caused by power supply fluctuations, and further ensures the reliability of the entire circuit and the accuracy of measurement. The D2 diode 23 and the D3 diode 24 together constitute the connection path of the power supply, transmitting the output power of the power management chip 21 to the operational amplifier chip 10. The D2 diode 23 can prevent the excessive voltage in the power supply from entering the operational amplifier chip 10. When the power supply voltage exceeds the forward conduction voltage of the D2 diode 23, it will bypass the excess voltage to prevent the excessive voltage from damaging the operational amplifier chip 10. At the same time, the cooperation between D2 diode 23 and D3 diode 24 provides a stable power supply path for the operational amplifier chip 10, ensuring that the operational amplifier chip 10 can work stably under various power supply conditions, ensuring the reliability of the power supply of the entire circuit, and is an important guarantee for the normal operation of the entire circuit.

[0036] According to the above content, the feedback circuit is composed of an operational amplifier chip 10, whose 1 pin and 3 pin are respectively connected to the feedback end of the sensor, and the power supply ends of 2 and 6 are provided by a power management chip 21. The 4 pin and 5 pin of the operational amplifier are short-circuited and connected to one end of the 1k resistor R9 and one end of the 300Ω resistor R12 respectively. The other end of the resistor 14 is connected to the 2.4M resistor R13 and the cathode of the switching diode D7. The other end of the resistor R13 is connected to the other end of R9, and then connected to the VERF- terminal of the AD chip. The positive electrode of the diode D7 is connected to the cathode of the diode D6, and the positive electrode of D6 is connected to the cathode of the diode D5. The positive electrode of the diode D5 is connected to the cathode of the diode D4, and the positive electrode of D4 is connected to the 300Ω resistor R10 and the 2.4M resistor R11 respectively. The op amp chip 10 op amp pins 7 and 8 are shorted and connected to one end of the 300Ω R10 resistor 12, and also connected to the 1k R8 resistor 11. The other end of the resistor R8 is connected to the resistor R11 and then enters the VREF+ of the AD chip.

[0037] The power supply of the operational amplifier chip 10 is provided by the power management chip 21. Pins 1, 3, 6 and 7 of the power management chip 21 are left unconnected, pin 2 is connected to the negative electrode of the 22uFC5 capacitor, the positive electrode of the C5 capacitor is connected to the positive electrode of the D3 diode 24, the negative electrode of the D3 diode 24 is connected to pin 6 of the operational amplifier chip 10, the positive electrode of the D3 diode 24 is connected to the negative electrode of the 100pF C5 capacitor, and the positive electrode of the C7 capacitor 25 is connected to pin 2 of the operational amplifier chip 10. The negative electrode of D3 is also connected to the positive electrode of the 22uF C6 capacitor, the negative electrode of the C6 capacitor is grounded, the 2nd pin of the power management chip 21 is simultaneously connected to the positive electrode of the 22uF C4 capacitor, the negative electrode of the C4 capacitor is connected to the 4th pin of the power management chip 21, the 5th pin of the power management chip 21 is connected to the positive electrode of the 22uF C3 capacitor 22, the negative electrode of the C3 capacitor 22 is connected to the ground, the 5th pin of the power management chip 21 is connected to the 2nd pin of the op amp chip 10, the 8th pin of the power management chip 21 is connected to the 5V power supply, the 5V capacitor is connected to the positive electrode of the D2 diode 23, the negative electrode of the D2 diode 23 is connected to the positive electrode of the D3 diode 24, and the negative electrode of the D3 diode 24 is connected to the 6th pin of the op amp chip 10.

[0038] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A feedback circuit for improving the measurement accuracy of a strain sensor, characterized in that: include: Power supply circuit, operational amplifier chip and filter circuit; The power supply circuit is electrically connected to the operational amplifier chip to supply power to the operational amplifier chip; The input end of the filter circuit is electrically connected to the operational amplifier chip, and the output end is suitable for being connected to the reference voltage electrical end of the AD chip to avoid overshoot.

2. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 1, characterized in that: Pin 1 and pin 3 of the operational amplifier chip are suitable for being electrically connected to the feedback end of the sensor.

3. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 1, characterized in that: It also includes resistors R9 and R12; Pins 4 and 5 of the operational amplifier chip are short-circuited, electrically connected to the R9 resistor and the R12 resistor, and participate in signal regulation.

4. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 3, characterized in that: It also includes resistors R13 and R9; The R13 resistor is short-circuited with the R9 resistor and is electrically connected to the negative terminal of the reference voltage of the AD chip for signal processing.

5. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 4, characterized in that: Also includes: R10 resistor and R8 resistor; The 7th pin and the 8th pin of the operational amplifier chip are short-circuited and electrically connected to the R10 resistor and the R8 resistor to process and transmit the signal.

6. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 5, characterized in that: The R10 resistor is electrically connected to the R11 resistor, and the R8 resistor is short-circuited with the R11 resistor and electrically connected to the positive terminal of the reference voltage of the AD chip to ensure the circuit function.

7. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 6, characterized in that: Also includes: R13 resistor, D7 diode, D6 diode, D5 diode and D4 diode; The R12 resistor is electrically connected to the R13 resistor and the cathode of the D7 diode, the anode of the D7 diode is electrically connected to the cathode of the D6 diode, the anode of the D6 diode is electrically connected to the cathode of the D5 diode, the anode of the D5 diode is electrically connected to the cathode of the D4 diode, and the anode of the D4 diode is electrically connected to the R10 resistor and the R11 resistor, respectively.

8. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 1, characterized in that: The power supply circuit includes: power management chip, C5 capacitor and D3 diode; Pin 2 of the power management chip is electrically connected to the negative electrode of the C5 capacitor, the positive electrode of the C5 capacitor is electrically connected to the positive electrode of the D3 diode, and the negative electrode of the D3 diode is electrically connected to pin 6 of the power management chip.

9. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 8, characterized in that: Also includes: C7 capacitor; The positive electrode of the D3 diode is electrically connected to the negative electrode of the C7 capacitor, and the positive electrode of the C7 capacitor is electrically connected to pin 2 of the operational amplifier chip.

10. The feedback circuit for improving the measurement accuracy of a strain sensor according to claim 9, characterized in that: Also includes D2 diode and power supply; The 8 pins of the power management chip are electrically connected to the power supply, and are electrically connected to the operational amplifier chip through the D2 diode and the D3 diode.

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