High resolution voltage sampling circuit

Abstract

The utility model relates to a kind of high-resolution voltage sampling circuit.It includes: voltage conversion circuit, with voltage divider circuit and sampling processor adaptation connection, at least voltage conversion is carried out to measurement voltage division, and the reference voltage generated by voltage conversion is loaded to the first AD channel of sampling processor, and the reference voltage difference generated by difference operation is loaded to the second AD channel of sampling processor, wherein, reference voltage difference is generated by voltage conversion circuit by reference voltage and reference voltage difference operation, and reference voltage is generated by sampling processor at least based on the reference voltage configuration received;Based on the reference voltage received and reference voltage difference, the sampling voltage value corresponding to measurement signal voltage is generated in sampling processor.The utility model can effectively realize high-resolution voltage sampling, reduce the cost and complexity of voltage sampling.

Description

Technical Field

[0001] This utility model relates to a voltage sampling circuit, and more particularly to a high-resolution voltage sampling circuit. Background Technology

[0002] Modern electronic devices include switching power supplies, instruments, and other equipment. In the operation of modern electronic devices, the parameters of physical quantities are generally obtained by sampling the converted voltage signals by an ADC. Physical quantity parameters such as voltage, current, temperature, flow rate, pressure, and torque are generally converted into voltage parameters by their corresponding sensors, then converted by the ADC and sensed by embedded hardware systems such as MCUs. The parameters are then used for display or for various data processing tasks by the host computer system.

[0003] As explained above, voltage and current acquisition or sampling is an essential operation for modern electronic devices. To achieve precise control of electronic equipment, accurate acquisition of relevant parameters or changes is required. Obtaining high-precision, high-resolution parameters is generally achieved through high-resolution or high-precision ADCs. Typically, the price of a high-precision or high-resolution ADC can be several times or even tens of times that of a low-resolution ADC. Therefore, using a high-resolution ADC for sampling leads to a rapid increase in cost.

[0004] Furthermore, in order to expand the measurement range, multiple high-precision ADCs may be used simultaneously; therefore, how to effectively achieve high-precision, high-resolution parameter sampling is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a high-resolution voltage sampling circuit that can effectively achieve high-resolution voltage sampling and reduce the cost and complexity of voltage sampling.

[0006] According to the technical solution provided by this utility model, a high-resolution voltage sampling circuit is provided, the voltage sampling circuit comprising: A voltage divider circuit is used to divide the voltage of the measurement signal and generate the measurement voltage after the voltage division. A voltage conversion circuit, adapted and connected to a voltage divider circuit and a sampling processor, performs voltage conversion on at least the measured voltage divider, applies the reference voltage generated by the voltage conversion to the first AD channel of the sampling processor, and applies the reference voltage difference generated by the difference calculation to the second AD channel of the sampling processor. The reference voltage difference is generated by the voltage conversion circuit by performing a difference calculation between the reference voltage and the reference voltage, and the reference voltage is generated by the sampling processor based at least on the received reference voltage. Based on the received reference voltage and the difference between the reference and reference voltages, a sampled voltage value corresponding to the measured signal voltage is generated in the sampling processor. Within the sampling processor, the minimum conversion resolution of the second AD channel is no greater than the minimum conversion resolution of the first AD channel.

[0007] The voltage conversion circuit includes at least a voltage conversion branch and a difference calculation branch, wherein... The voltage transformation branch is connected to the voltage divider branch. The voltage transformation branch amplifies the measured voltage divider at least once and applies the amplified reference voltage to the first AD channel of the sampling processor, and applies the reference voltage to the difference calculation branch. The difference calculation branch calculates the difference between the reference voltage and the reference voltage, and loads the generated reference voltage difference into the second AD channel of the sampling processor.

[0008] The voltage conversion branch includes an operational amplifier U1, wherein... The non-inverting input of operational amplifier U1 is connected to a voltage divider circuit to receive the measured voltage. The inverting input and output of operational amplifier U1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the non-inverting input of operational amplifier U2. The inverting input of operational amplifier U2 is connected to one end of resistor R4, the other end of resistor R4 is grounded and connected to one end of resistor R5, the other end of resistor R5 is connected to the output of operational amplifier U2 and one end of resistor R6. The other end of resistor R6 is connected to the first AD channel of the sampling processor, one end of capacitor C1, and the difference calculation branch.

[0009] The difference operation branch includes operational amplifier U3, wherein... The non-inverting input of operational amplifier U3 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 is connected to the voltage conversion branch adapter to receive the reference voltage, and the other end of resistor R10 is grounded. The inverting input of operational amplifier U3 is connected to one end of resistor R8 and the differential operational feedback resistor unit. The other end of resistor R8 is connected to the reference voltage. The differential operational feedback resistor unit is also connected to the output of operational amplifier U3 and one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C2 and the second AD channel of the sampling processor.

[0010] The difference calculation feedback resistor unit includes at least one difference calculation feedback resistor branch, wherein, When the difference operation feedback resistor unit includes multiple difference operation feedback resistor branches, all difference operation feedback resistor branches are connected in parallel; Each differential operation feedback resistor branch includes one differential operation feedback resistor; The difference operation feedback resistor branch is connected to the difference feedback switch network so that at least one difference operation feedback resistor branch can be selected via the difference feedback switch network.

[0011] The differential feedback switch network includes several branch switches or a multiplexer switch, wherein, When the differential feedback switch network consists of multiple branch switches, at least one branch switch is configured to be connected to a differential operation feedback resistor branch so as to use one branch switch to configure the feedback state of the differential operation feedback resistor branch. When the differential feedback switch network is a multiplexer, the common terminal of the multiplexer is connected to the inverting terminal of the operational amplifier U3, and the selection terminal of the multiplexer is connected to a corresponding differential operational feedback resistor branch.

[0012] A reference voltage generation circuit is provided within the voltage conversion circuit, and the reference voltage generation circuit is connected to the sampling processor. The reference voltage generation circuit includes a DAC unit or a PWM signal conversion circuit; When the reference voltage generation circuit is a DAC unit, the DAC unit converts the reference digital signal output by the sampling processor into a reference voltage. When the reference voltage generation circuit is a PWM signal conversion circuit, the PWM signal output by the sampling processor is converted into a reference voltage through the PWM signal conversion circuit.

[0013] The PWM signal conversion circuit includes an operational amplifier U6, wherein... The non-inverting input of the operational amplifier U6 is connected to one end of resistor R12, one end of resistor R13, and one end of capacitor C3. The other end of resistor R12 and the other end of capacitor C3 are grounded, and the other end of resistor R13 is connected to the PWM signal output by the sampling processor. The output terminal of operational amplifier U6 is connected to the output terminal of operational amplifier U6, and the reference voltage is output through the output terminal of operational amplifier U6.

[0014] The voltage divider circuit includes at least resistor R1 and resistor R2, wherein, One end of resistor R1 is connected to the measured signal voltage, the other end of resistor R1 is connected to the voltage conversion circuit and one end of resistor R2, and the other end of resistor R2 is grounded.

[0015] The sampling processor includes a microprocessor, and the reference voltage and the reference voltage difference are respectively located at the port voltage withstand values ​​of the first AD channel and the second AD channel.

[0016] The advantages of this invention are as follows: The measured voltage is amplified by a voltage conversion circuit and a reference voltage is formed and applied to the first AD channel of the sampling processor. Subsequently, the sampling processor generates a corresponding reference voltage. Within the voltage conversion circuit, the reference voltage and the reference voltage are compared to generate a reference-reference voltage difference, which is then applied to the second AD channel of the sampling processor. Based on the reference voltage and the reference-reference voltage difference, the sampling processor can generate a sampling voltage value corresponding to the measured signal voltage, thereby effectively achieving high-resolution voltage sampling and reducing the cost and complexity of voltage sampling. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of one embodiment of the voltage sampling circuit of this utility model.

[0018] Figure 2 This is a circuit diagram of one embodiment of the present invention that uses a PWM signal conversion circuit to generate a reference voltage.

[0019] Figure 3 This is a circuit diagram of an embodiment of the differential operation feedback resistor unit of this utility model, which uses a multiplexer switch. Detailed Implementation

[0020] The present invention will be further described below with reference to the specific accompanying drawings and embodiments.

[0021] To effectively achieve high-resolution voltage sampling and reduce the cost and complexity of voltage sampling, this invention provides a high-resolution voltage sampling circuit. Specifically, the voltage sampling circuit includes: A voltage divider circuit is used to divide the voltage of the measurement signal and generate the measurement voltage after the voltage division. A voltage conversion circuit, adapted and connected to a voltage divider circuit and a sampling processor, performs voltage conversion on at least the measured voltage divider, applies the reference voltage generated by the voltage conversion to the first AD channel of the sampling processor, and applies the reference voltage difference generated by the difference calculation to the second AD channel of the sampling processor. The reference voltage difference is generated by the voltage conversion circuit by performing a difference calculation between the reference voltage and the reference voltage, and the reference voltage is generated by the sampling processor based at least on the received reference voltage. Based on the received reference voltage and the difference between the reference and reference voltages, a sampled voltage value corresponding to the measured signal voltage is generated in the sampling processor. Within the sampling processor, the minimum conversion resolution of the second AD channel is no greater than the minimum conversion resolution of the first AD channel.

[0022] Figure 1The diagram shows a circuit schematic of one embodiment of the voltage sampling circuit of this utility model. As can be seen from the diagram, the voltage sampling circuit of this utility model should include a voltage divider circuit, a voltage conversion circuit, and a sampling processor. The following will describe this in conjunction with... Figure 1 The circuit diagram shown in the figure provides a detailed explanation of the voltage divider circuit, voltage conversion circuit, and sampling processor.

[0023] As explained above, electronic devices use sensors to measure physical parameters and generate measurement signal voltages. Voltage divider circuits divide these measurement signal voltages, generating a measurement voltage. It's understood that the measurement voltage should generally be less than the measurement signal voltage. Figure 1 In To measure the signal voltage, the generated measurement voltage divider is applied to the voltage conversion circuit. The voltage conversion circuit first converts the measurement voltage divider, and then generates a reference voltage. It should be noted that the purpose of the voltage conversion is mainly to meet the processing requirements of the sampling processor.

[0024] In practical implementation, the sampling processor should include two AD channels, which form a first AD channel and a second AD channel, respectively. Generally, the minimum conversion resolution of the second AD channel is not greater than that of the first AD channel. Figure 1 The MCU in the text is the sampling processor. Furthermore, Figure 2 The MCU in this context also refers to the sampling processor. After the voltage is converted to a reference voltage, the reference voltage is sent to the first AD channel of the sampling processor. The sampling processor can be a commonly used microprocessor, such as a single-chip microcomputer. The form of the sampling processor can be selected as needed, such as having at least the aforementioned first AD channel and second AD channel, specifically to meet the voltage sampling requirements of this utility model.

[0025] After the voltage reference is sent to the sampling processor, the sampling processor can perform conversion processing using existing common methods to generate a voltage signal with a minimum resolution of N1 within the sampling processor. This voltage signal can be denoted as: ,in, The reference voltage, This refers to the voltage signal obtained within the sampling processor. It can be understood that the voltage signal... For digital signals, reference voltage This is a simulated voltage.

[0026] In order to achieve high-resolution voltage sampling, the sampling processor can generate a voltage signal based on the minimum resolution of the second AD channel. voltage signal It is a digital signal. This is the minimum resolution of the second AD channel. Because of the minimum resolution of the second AD channel... If the resolution is not greater than the minimum resolution N1 of the first AD channel, then: Based on voltage signal A reference voltage can be generated. It should be understood that the reference voltage is an analog signal, but its value is less than the value corresponding to the reference voltage V1. Figure 1 In this context, Vref is the reference voltage.

[0027] After generating the reference voltage, the voltage conversion circuit performs a difference calculation between the reference voltage and the base voltage to obtain the reference voltage difference. The obtained reference voltage difference can be:

[0028] Where m is the scaling factor when performing the difference operation.

[0029] After generating the reference voltage difference, it should be loaded into the second AD channel of the sampling processor. Since the reference voltage difference is an analog signal, a voltage signal will be generated within the sampling processor after it is loaded into the second AD channel. voltage signal As a digital signal, it can be understood as a voltage signal. Corresponding to the difference in voltage with the reference voltage. After obtaining the voltage signal... , to voltage signal and voltage signal Adding these signals together yields a voltage signal with higher resolution than the first AD channel, capable of representing the sampled voltage value; at this point, voltage sampling is complete. As explained above, due to the voltage signal... Voltage signal generated based on reference voltage. Based on the reference voltage difference, the meaning of the above description regarding the generation of the sampled voltage value within the sampling processor can be determined.

[0030] It should be understood that the reference voltage and the difference between the reference and reference voltages are located at the port voltage withstand values ​​corresponding to the first and second AD channels, respectively. The principle of this invention's ability to achieve high-resolution voltage sampling is illustrated below with an example: When the set sampling voltage value is 3.1V, the corresponding measured signal voltage is 3100V, and the maximum range is 3300V; the port voltage corresponding to the first AD channel and the second AD channel of the sampling processor is 3.3V, that is, the maximum withstand voltage corresponding to the ports of the first AD channel and the second AD channel is 3.3V, the ADCs corresponding to the first AD channel and the second AD channel both have a resolution of 8bit. If only the first AD channel is used for voltage sampling, the minimum resolution value during voltage sampling is: 3300V / 2 8 =12.89V.

[0031] When voltage sampling is performed by the cooperation of the first AD channel and the second AD channel, the voltage signal is set to 2.9V, and the reference voltage generated by the sampling processor configuration is 2.9V. Therefore, the reference reference voltage difference applied to the second AD channel is: , when m is 10 (1<m<VREF*2^B1*n / Vmax), the obtained minimum resolution value is: 3300V / 10 / 2 8 =1.28V; it can be seen that the minimum resolution becomes smaller, the sampled value is more accurate, and the obtained sampling voltage values can be shown in the following table, specifically: Table 1

[0032] It should be noted that if the least significant bit of the value (minimum resolution) still cannot meet the requirements, you can try to modify the proportional coefficient m to continuously improve the accuracy; however, the proportional coefficient m cannot be expanded indefinitely, which is limited by the resolution of the DAC or the reference reference voltage difference, as well as the voltage withstand range of the second AD port, and the value range of the proportional coefficient m can refer to the above description.

[0033] In addition, if you want to further reduce the value of the minimum resolution, you can repeat the above steps for another iterative operation, and finally obtain the desired minimum resolution, wherein repeating the above steps means repeating the above process of generating the reference voltage and performing the above difference operation to generate the reference reference voltage difference; specifically, during the repeated operation, the reference voltage generated by the sampling processor configuration can gradually approach 0, for example, the reference voltage generated the second time should be smaller than the reference voltage generated the first time, which is specifically subject to effectively reducing the value of the minimum resolution.

[0034] In an embodiment of the present utility model, the voltage conversion circuit at least includes a voltage conversion branch and a difference operation branch, wherein, The voltage conversion branch is connected to the voltage divider branch, the voltage conversion branch at least amplifies the measured divided voltage, applies the amplified reference voltage to the first AD channel of the sampling processor, and applies the reference voltage to the difference operation branch; The difference calculation branch calculates the difference between the reference voltage and the reference voltage, and loads the generated reference voltage difference into the second AD channel of the sampling processor.

[0035] To achieve the voltage transformation and difference calculation functions described above, the voltage transformation circuit should include at least a voltage transformation branch and a difference calculation branch. The voltage transformation branch should amplify the measured voltage divider, and the difference calculation branch should perform the difference calculation. The following section will discuss this further. Figures 1-3 Examples are given for voltage transformation branches and difference calculation branches.

[0036] In one embodiment of this utility model, the voltage transformation branch includes an operational amplifier U1, wherein... The non-inverting input of operational amplifier U1 is connected to a voltage divider circuit to receive the measured voltage. The inverting input and output of operational amplifier U1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the non-inverting input of operational amplifier U2. The inverting input of operational amplifier U2 is connected to one end of resistor R4, the other end of resistor R4 is grounded and connected to one end of resistor R5, the other end of resistor R5 is connected to the output of operational amplifier U2 and one end of resistor R6. The other end of resistor R6 is connected to the first AD channel of the sampling processor, one end of capacitor C1, and the difference calculation branch.

[0037] Depend on Figure 1 It can be seen that operational amplifier U1 can implement a voltage follower. Furthermore, Figure 1 The diagram also shows a schematic of one embodiment of a voltage divider circuit. In the diagram, the voltage divider circuit includes at least resistor R1 and resistor R2. One end of resistor R1 is connected to the measured signal voltage, and the other end of resistor R1 is connected to the voltage conversion circuit (the non-inverting input of operational amplifier U1) and one end of resistor R2. The other end of resistor R2 is grounded. Of course, the voltage divider circuit can also take other forms, depending on whether it can achieve the purpose of voltage division. These will not be illustrated here.

[0038] In one embodiment of this utility model, the difference operation branch includes an operational amplifier U3, wherein... The non-inverting input of operational amplifier U3 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 is connected to the voltage conversion branch adapter to receive the reference voltage, and the other end of resistor R10 is grounded. The inverting input of operational amplifier U3 is connected to one end of resistor R8 and the differential operational feedback resistor unit. The other end of resistor R8 is connected to the reference voltage. The differential operational feedback resistor unit is also connected to the output of operational amplifier U3 and one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C2 and the second AD channel of the sampling processor.

[0039] In specific implementation, the difference calculation feedback resistor unit includes at least one difference calculation feedback resistor branch, wherein, When the difference operation feedback resistor unit includes multiple difference operation feedback resistor branches, all difference operation feedback resistor branches are connected in parallel; Each differential operation feedback resistor branch includes one differential operation feedback resistor; The difference operation feedback resistor branch is connected to the difference feedback switch network so that at least one difference operation feedback resistor branch can be selected via the difference feedback switch network.

[0040] Figure 1 The figure shows an embodiment of a differential operation amplification unit including a differential operation feedback resistor branch. In the figure, the differential operation feedback resistor branch is resistor R7. Since there is only one resistor R7, the differential operation feedback resistor unit may not include a differential feedback switch network. Of course, a switch can also be set in the differential operation feedback resistor branch where resistor R7 is located. The conduction state of the switch can be controlled by the sampling processor. In this case, the switch should be configured to be in the normally closed state during operation.

[0041] In one embodiment of this invention, the differential feedback switch network includes several branch switches or a multiplexer switch, wherein... When the differential feedback switch network consists of multiple branch switches, at least one branch switch is configured to be connected to a differential operation feedback resistor branch so as to use one branch switch to configure the feedback state of the differential operation feedback resistor branch. When the differential feedback switch network is a multiplexer, the common terminal of the multiplexer is connected to the inverting terminal of the operational amplifier U3, and the selection terminal of the multiplexer is connected to a corresponding differential operational feedback resistor branch.

[0042] Figure 3 The figure shows an embodiment of a differential feedback switch network using a multiplexer switch. In the figure, the MuxSwitch is the multiplexer switch, which can be formed using commonly used existing switching devices. Figure 3In this system, there are three differential operation feedback resistor branches, with resistors R71, R72, and R73 corresponding to these branches. It's understood that when using multiple branch switches, the number of branch switches should be no less than the number of differential operation feedback resistor branches, and each branch should have one branch switch. When a branch switch is closed, the corresponding differential operation feedback resistor branch is selected; otherwise, it is not. Based on the selected differential operation feedback resistor branch, the differential operation scaling factor m can be adjusted, allowing for the selection of the appropriate resolution according to the actual scenario.

[0043] In one embodiment of this invention, a reference voltage generation circuit is provided within the voltage conversion circuit, and the reference voltage generation circuit is connected to the sampling processor. The reference voltage generation circuit includes a DAC unit or a PWM signal conversion circuit; When the reference voltage generation circuit is a DAC unit, the DAC unit converts the reference digital signal output by the sampling processor into a reference voltage. When the reference voltage generation circuit is a PWM signal conversion circuit, the PWM signal output by the sampling processor is converted into a reference voltage through the PWM signal conversion circuit.

[0044] Figure 1 The diagram illustrates an embodiment of a reference voltage generation circuit employing a DAC unit. The DAC unit converts the reference digital signal from the sampling processor into a reference voltage. The DAC unit can adopt a commonly used form, specifically one capable of digital-to-analog conversion.

[0045] In one embodiment of this utility model, the PWM signal conversion circuit includes an operational amplifier U6, wherein... The non-inverting input of the operational amplifier U6 is connected to one end of resistor R12, one end of resistor R13, and one end of capacitor C3. The other end of resistor R12 and the other end of capacitor C3 are grounded, and the other end of resistor R13 is connected to the PWM signal output by the sampling processor. The output terminal of operational amplifier U6 is connected to the output terminal of operational amplifier U6, and the reference voltage is output through the output terminal of operational amplifier U6.

[0046] Figure 2 The diagram shows a circuit schematic of an embodiment of a PWM signal conversion circuit for generating a reference voltage. The sampling processor generates a PWM signal with a specific duty cycle, which is filtered by an RC filter composed of resistor R12 and capacitor C13. Finally, the reference voltage is output by a voltage follower formed by operational amplifier U6. The output reference voltage can be expressed as:

[0047] in, This represents the duty cycle value of the PWM signal. This refers to the amplitude of the PWM signal. As explained above, the sampling processor can configure the amplitude of the PWM signal based on the received reference voltage. This allows the generation of a reference voltage that satisfies the above description. It should be noted that the maximum voltage amplitude cannot exceed... Furthermore, the sampling processor cannot output a negative voltage; therefore, the range of the reference voltage is: .

Claims

1. A high-resolution voltage sampling circuit, characterized in that, The voltage sampling circuit includes: A voltage divider circuit is used to divide the voltage of the measurement signal and generate the measurement voltage after the voltage division. A voltage conversion circuit, adapted and connected to a voltage divider circuit and a sampling processor, performs voltage conversion on at least the measured voltage divider, applies the reference voltage generated by the voltage conversion to the first AD channel of the sampling processor, and applies the reference voltage difference generated by the difference calculation to the second AD channel of the sampling processor. The reference voltage difference is generated by the voltage conversion circuit by performing a difference calculation between the reference voltage and the reference voltage, and the reference voltage is generated by the sampling processor based at least on the received reference voltage. Based on the received reference voltage and the difference between the reference and reference voltages, a sampled voltage value corresponding to the measured signal voltage is generated in the sampling processor. Within the sampling processor, the minimum conversion resolution of the second AD channel is no greater than the minimum conversion resolution of the first AD channel.

2. The high-resolution voltage sampling circuit according to claim 1, characterized in that: The voltage conversion circuit includes at least a voltage conversion branch and a difference calculation branch, wherein... The voltage transformation branch is connected to the voltage divider branch. The voltage transformation branch amplifies the measured voltage divider at least once and applies the amplified reference voltage to the first AD channel of the sampling processor, and applies the reference voltage to the difference calculation branch. The difference calculation branch calculates the difference between the reference voltage and the reference voltage, and loads the generated reference voltage difference into the second AD channel of the sampling processor.

3. The high-resolution voltage sampling circuit according to claim 2, characterized in that: The voltage conversion branch includes an operational amplifier U1, wherein... The non-inverting input of operational amplifier U1 is connected to a voltage divider circuit to receive the measured voltage. The inverting input and output of operational amplifier U1 are connected to one end of resistor R3, and the other end of resistor R3 is connected to the non-inverting input of operational amplifier U2. The inverting input of operational amplifier U2 is connected to one end of resistor R4, the other end of resistor R4 is grounded and connected to one end of resistor R5, the other end of resistor R5 is connected to the output of operational amplifier U2 and one end of resistor R6. The other end of resistor R6 is connected to the first AD channel of the sampling processor, one end of capacitor C1, and the difference calculation branch.

4. The high-resolution voltage sampling circuit according to claim 2, characterized in that: The difference operation branch includes operational amplifier U3, wherein... The non-inverting input of operational amplifier U3 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 is connected to the voltage conversion branch adapter to receive the reference voltage, and the other end of resistor R10 is grounded. The inverting input of operational amplifier U3 is connected to one end of resistor R8 and the differential operational feedback resistor unit. The other end of resistor R8 is connected to the reference voltage. The differential operational feedback resistor unit is also connected to the output of operational amplifier U3 and one end of resistor R11. The other end of resistor R11 is connected to one end of capacitor C2 and the second AD channel of the sampling processor.

5. The high-resolution voltage sampling circuit according to claim 4, characterized in that: The difference calculation feedback resistor unit includes at least one difference calculation feedback resistor branch, wherein, When the difference operation feedback resistor unit includes multiple difference operation feedback resistor branches, all difference operation feedback resistor branches are connected in parallel; Each differential operation feedback resistor branch includes one differential operation feedback resistor; The difference operation feedback resistor branch is connected to the difference feedback switch network so that at least one difference operation feedback resistor branch can be selected via the difference feedback switch network.

6. The high-resolution voltage sampling circuit according to claim 5, characterized in that: The differential feedback switch network includes several branch switches or a multiplexer switch, wherein, When the differential feedback switch network consists of multiple branch switches, at least one branch switch is configured to be connected to a differential operation feedback resistor branch so as to use one branch switch to configure the feedback state of the differential operation feedback resistor branch. When the differential feedback switch network is a multiplexer, the common terminal of the multiplexer is connected to the inverting terminal of the operational amplifier U3, and the selection terminal of the multiplexer is connected to a corresponding differential operational feedback resistor branch.

7. The high-resolution voltage sampling circuit according to any one of claims 1 to 6, characterized in that: in The voltage conversion circuit includes a reference voltage generation circuit, which is connected to the sampling processor. The reference voltage generation circuit includes a DAC unit or a PWM signal conversion circuit; When the reference voltage generation circuit is a DAC unit, the DAC unit converts the reference digital signal output by the sampling processor into a reference voltage. When the reference voltage generation circuit is a PWM signal conversion circuit, the PWM signal output by the sampling processor is converted into a reference voltage through the PWM signal conversion circuit.

8. The high-resolution voltage sampling circuit according to claim 7, characterized in that: The PWM signal conversion circuit includes an operational amplifier U6, wherein... The non-inverting input of the operational amplifier U6 is connected to one end of resistor R12, one end of resistor R13, and one end of capacitor C3. The other end of resistor R12 and the other end of capacitor C3 are grounded, and the other end of resistor R13 is connected to the PWM signal output by the sampling processor. The output terminal of operational amplifier U6 is connected to the output terminal of operational amplifier U6, and the reference voltage is output through the output terminal of operational amplifier U6.

9. The high-resolution voltage sampling circuit according to any one of claims 1 to 6, characterized in that: The voltage divider circuit includes at least resistor R1 and resistor R2, wherein, One end of resistor R1 is connected to the measured signal voltage, the other end of resistor R1 is connected to the voltage conversion circuit and one end of resistor R2, and the other end of resistor R2 is grounded.

10. The high-resolution voltage sampling circuit according to any one of claims 1 to 6, characterized in that: The sampling processor includes a microprocessor, and the reference voltage and the reference voltage difference are respectively located at the port voltage withstand values ​​of the first AD channel and the second AD channel.

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