Small signal sampling amplification circuit, circuit board and signal sampling device

Abstract

The utility model discloses a small signal sampling amplification circuit, a circuit board and a signal sampling device, the circuit comprises a sampling voltage division circuit, an isolation amplification circuit and an adjustable amplification circuit, one end of the sampling voltage division circuit is used for acquiring a signal of an access side, and the other end of the sampling voltage division circuit is grounded; the isolation amplification circuit comprises an isolation amplifier, and a first input end and a second input end of the isolation amplifier are respectively connected with two voltage division output ends of the sampling voltage division circuit; the adjustable amplification circuit comprises a first operational amplifier, the non-inverting input end of the first operational amplifier is connected with the first output end of an isolation amplifier, the inverting input end of the first operational amplifier is connected with the second output end of the isolation amplifier, and an adjustable resistor is connected between the inverting input end and the output end of the first operational amplifier. The output end of the first operational amplifier is further used for being connected with an external controller to sense the signal state of the access side. According to the invention, the sampling signal can be electrically isolated, the amplification gain is adjustable, and the sampling precision is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a small signal sampling and amplifying circuit, a circuit board and a signal sampling device. Background Art

[0002] In the circuit industry, in order to monitor the operating status of electrical equipment during operation, it is usually necessary to obtain the voltage / current signal fed back by the electrical equipment through a sampling circuit, and to analyze the changes or fluctuations of the electrical signal to provide real-time feedback on the operating status of the corresponding equipment. In some devices, the signal that the sampling circuit can obtain is small, which is not convenient for the controller to analyze the signal. Therefore, the sampling circuit usually needs to amplify the signal after collecting the signal from the access side. It is common in the industry to directly amplify the operational amplifier with adjustable gain. The noise and interference of the input signal will interfere with and affect the output signal. In addition, there is an isolated fixed gain amplifier circuit, and the output signal cannot reach the final desired size or range. The amplification effect of the existing small signal sampling circuit is not ideal. Utility Model Content

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a small signal sampling and amplification circuit, a circuit board and a signal sampling device, which can achieve electrical isolation of the sampling signal, adjustable amplification gain and improve sampling accuracy.

[0004] In a first aspect, the present application provides a small signal sampling and amplification circuit, comprising:

[0005] A sampling voltage divider circuit, one end of which is used to obtain a signal from the access side, and the other end of which is grounded;

[0006] An isolation amplifier circuit, the isolation amplifier circuit comprising an isolation amplifier, a first input terminal and a second input terminal of the isolation amplifier being respectively connected to two voltage-dividing output terminals of the sampling voltage-dividing circuit;

[0007] An adjustable amplifier circuit includes a first operational amplifier, a non-phase input terminal of the first operational amplifier is connected to a first output terminal of the isolation amplifier, an inverting input terminal of the first operational amplifier is connected to a second output terminal of the isolation amplifier, an adjustable resistor is connected between the inverting input terminal and the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is also used to connect to an external controller to sense the signal state of the access side.

[0008] According to the small signal sampling and amplification circuit of the first aspect of the embodiment of the present application, at least the following beneficial effects are achieved: a sampling signal is acquired from the access side through a sampling voltage divider circuit, and the sampling signal is then input into an isolation amplifier circuit, and the signal is isolated and amplified using an isolation amplifier, and then the signal after one processing is input into an adjustable amplifier circuit, in which the gain of the first operational amplifier can be changed by adjusting the resistance of the adjustable resistor, so that it can be adjusted according to the range of the signal value that can be received by the external controller, so as to more accurately receive the signal from the access side and realize analysis. The overall structure of the circuit of the present application is simple, and it can prevent the noise, interference and position difference in the input signal from interfering with the output signal, improve the stability and anti-interference ability of the system, and provide safety protection, specifically through isolation to prevent high voltage or high current from being transmitted from the input end to the output end, thereby protecting the safety of the instrument and the operator, and the signal amplification gain is adjustable and has high precision.

[0009] According to some embodiments of the first aspect of the present application, it also includes an isolated power supply circuit, the input end of the isolated power supply circuit is used to connect to the power supply, and the output end of the isolated power supply circuit is respectively connected to the isolated amplifier circuit and the adjustable amplifier circuit.

[0010] According to some embodiments of the first aspect of the present application, the isolated power supply circuit includes a first voltage stabilizing chip and a second voltage stabilizing chip, the input end of the first voltage stabilizing chip is used to connect to the power supply, the first output end of the first voltage stabilizing chip is connected to the first power supply end of the isolation amplifier, the second output end of the first voltage stabilizing chip is connected to the input end of the second voltage stabilizing chip, and the output end of the second voltage stabilizing chip is respectively connected to the second power supply end of the isolation amplifier and the positive power supply end of the first operational amplifier.

[0011] According to some embodiments of the first aspect of the present application, a bias power supply circuit is further included, wherein the bias power supply circuit includes a second operational amplifier, a non-phase input terminal of the second operational amplifier is connected to the output terminal of the second voltage regulator chip through a first resistor, the non-phase input terminal of the second operational amplifier is also grounded through a second resistor, the inverting input terminal of the second operational amplifier is grounded through a third resistor, a fourth resistor is connected between the inverting input terminal and the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the non-phase input terminal of the first operational amplifier through a fifth resistor.

[0012] According to some embodiments of the first aspect of the present application, the sampling voltage divider circuit includes a plurality of resistors connected in series in sequence, the two ends of a sixth resistor of the sampling voltage divider circuit close to the ground end are voltage divider output ends of the sampling voltage divider circuit, one end of the sixth resistor close to the access side is connected to the first input end of the isolation amplifier, and one end of the sixth resistor close to the ground end is connected to the second input end of the isolation amplifier.

[0013] According to some embodiments of the first aspect of the present application, the first input terminal of the isolation amplifier is connected to one of the voltage divider output terminals of the sampling voltage divider circuit through a seventh resistor, the second input terminal of the isolation amplifier is connected to the other voltage divider output terminal of the sampling voltage divider circuit through an eighth resistor, and a first capacitor is connected between the seventh resistor and one end of the eighth resistor connected to the isolation amplifier.

[0014] According to some embodiments of the first aspect of the present application, the non-inverting input terminal of the first operational amplifier is connected to the first output terminal of the isolation amplifier through a ninth resistor, the inverting input terminal of the first operational amplifier is connected to the second output terminal of the isolation amplifier through a tenth resistor, and a second capacitor is connected between the ninth resistor and one end of the tenth resistor connected to the first operational amplifier.

[0015] According to some embodiments of the first aspect of the present application, the output end of the first operational amplifier is connected to the external controller via an eleventh resistor, and the eleventh resistor and the external controller are grounded via a third capacitor.

[0016] In a second aspect, the present application further provides a circuit board, comprising the small signal sampling and amplifying circuit as described in any one embodiment of the first aspect.

[0017] In a third aspect, the present application also provides a signal sampling device, comprising a circuit board as described in the embodiment of the second aspect.

[0018] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0020] Figure 1 A schematic block diagram of a small signal sampling and amplification circuit provided in some embodiments of the present application;

[0021] Figure 2 A circuit diagram of a small signal sampling and amplifying circuit provided in some embodiments of the present application;

[0022] Figure 3 A circuit diagram of an isolated power supply circuit provided in some embodiments of the present application;

[0023] Figure 4 A circuit diagram of a bias power supply circuit provided for some embodiments of the present application.

[0024] The figures are as follows:

[0025] Sampling voltage-dividing circuit 100 ; isolation amplifier circuit 200 ; adjustable amplifier circuit 300 ; isolation power supply circuit 400 ; bias power supply circuit 500 ; controller 600 . DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0027] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0028] In the description of this application, if there is a description of first or second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0029] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0030] In the circuit industry, in order to monitor the operating status of electrical equipment during operation, it is usually necessary to obtain the voltage / current signal fed back by the electrical equipment through a sampling circuit, and to analyze the changes or fluctuations of the electrical signal to provide real-time feedback on the operating status of the corresponding equipment. In some devices, the signal that the sampling circuit can obtain is small, which is not convenient for the controller to analyze the signal. Therefore, the sampling circuit usually needs to amplify the signal after collecting the signal from the access side. It is common in the industry to directly amplify the operational amplifier with adjustable gain. The noise and interference of the input signal will interfere with and affect the output signal. In addition, there is an isolated fixed gain amplifier circuit, and the output signal cannot reach the final desired size or range. The amplification effect of the existing small signal sampling circuit is not ideal.

[0031] Based on this, the present application provides a small signal sampling and amplification circuit, a circuit board and a signal sampling device to solve the above-mentioned technical problems. The technical solutions provided by the present application are described in detail one by one below.

[0032] First, refer to Figure 1 and Figure 2The present application provides a small signal sampling and amplifying circuit, comprising: a sampling voltage divider circuit 100, an isolation amplifying circuit 200 and an adjustable amplifying circuit 300, wherein one end of the sampling voltage divider circuit 100 is used to obtain a signal from an access side, and the other end of the sampling voltage divider circuit 100 is grounded; the isolation amplifying circuit 200 comprises an isolation amplifier U1, wherein a first input end and a second input end of the isolation amplifier U1 are respectively connected to two voltage divider output ends of the sampling voltage divider circuit 100; the adjustable amplifying circuit 300 comprises a first operational amplifier U2, wherein a non-inverting input end of the first operational amplifier U2 is connected to a first output end of the isolation amplifier U1, an inverting input end of the first operational amplifier U2 is connected to a second output end of the isolation amplifier U1, an adjustable resistor Rv is connected between the inverting input end and the output end of the first operational amplifier U2, and the output end of the first operational amplifier U2 is also used to connect to an external controller 600 to sense the signal state of the access side. The sampling voltage divider circuit 100 obtains the acquisition signal from the access side, and then inputs the sampling signal into the isolation amplifier circuit 200, and uses the isolation amplifier U1 to isolate and amplify the signal, and then the signal after one processing is input into the adjustable amplifier circuit 300, in which the gain of the first operational amplifier U2 can be changed by adjusting the resistance of the adjustable resistor Rv, so that it can be adjusted according to the range of the signal value that can be received by the external controller 600, so as to more accurately receive the signal from the access side and realize the analysis. The overall structure of the circuit of the present application is simple, which can prevent the noise, interference and position difference in the input signal from interfering with the output signal, improve the stability and anti-interference ability of the system, and provide safety protection. Specifically, the isolation effect prevents high voltage or high current from being transmitted from the input end to the output end, thereby protecting the safety of the instrument and the operator, and the signal amplification gain is adjustable and the accuracy is high.

[0033] It should be noted that, refer to Figure 2 In the embodiment of the present application, the first input terminal, the second input terminal, the first output terminal and the second output terminal of the isolation amplifier U1 are respectively the second pin, the third pin, the seventh pin and the sixth pin of the isolation amplifier U1 chip. In addition, the first pin, the fourth pin, the fifth pin and the eighth pin of the isolation amplifier U1 chip are respectively the first power supply terminal, the first ground terminal, the second ground terminal and the second power supply terminal of the isolation amplifier U1. The pin positions of the specific isolation amplifier U1 vary according to the isolation amplifier U1 with different chip models selected by relevant personnel, and are not limited in the present application.

[0034] Reference Figure 1It can be understood that the small signal sampling and amplifying circuit provided in the present application also includes an isolated power supply circuit 400, the input end of the isolated power supply circuit 400 is used to connect to the power supply, and the output end of the isolated power supply circuit 400 is respectively connected to the isolated amplifier circuit 200 and the adjustable amplifier circuit 300. The isolated power supply circuit 400 converts the voltage of the power supply into a stable voltage to provide power for the isolated amplifier circuit 200 and the adjustable amplifier circuit 300, specifically to provide power for the isolation amplifier U1 and the first operational amplifier U2. The isolated power supply circuit 400 can convert the voltage of the power supply into a variety of different stable voltages, which is not limited in the present application.

[0035] Reference Figure 3 It can be understood that the isolated power supply circuit 400 includes a first voltage stabilizing chip U3 and a second voltage stabilizing chip U4, the input end of the first voltage stabilizing chip U3 is used to connect to the power supply, the first output end of the first voltage stabilizing chip U3 is connected to the first power supply end of the isolation amplifier U1, the second output end of the first voltage stabilizing chip U3 is connected to the input end of the second voltage stabilizing chip U4, and the output end of the second voltage stabilizing chip U4 is respectively connected to the second power supply end of the isolation amplifier U1 and the positive power supply end of the first operational amplifier U2. In the embodiment of the present application, the voltage of the power supply is 24V, and the voltage is stably reduced to 5V through the action of the first voltage stabilizing chip U3, and is output by the first output end and the second output end of the first voltage stabilizing chip U3. The two output ends are separated to prevent the two voltages from affecting each other due to the subsequent circuit, wherein the first output end is connected to the first power supply end of the isolation amplifier U1, specifically to provide power for the primary coil of the isolation amplifier U1. The second output end of the first voltage stabilizing chip U3 is connected to the input end of the second voltage stabilizing chip U4. The second voltage stabilizing chip U4 is used to stably reduce the input 5V voltage to 3.3V. The output end of the second voltage stabilizing chip U4 is respectively connected to the second power supply end of the isolation amplifier U1 and the positive power supply end of the first operational amplifier U2, specifically to provide power to the secondary coil of the isolation amplifier U1 and the first operational amplifier U2 respectively. The specific voltage provided for each circuit is not limited in this application.

[0036] Reference Figure 1 and Figure 4It can be understood that the small signal sampling and amplifying circuit provided in the present application also includes a bias power supply circuit 500, and the bias power supply circuit 500 includes a second operational amplifier U5, the non-phase input terminal of the second operational amplifier U5 is connected to the output terminal of the second voltage regulator chip U4 through the first resistor R1, the non-phase input terminal of the second operational amplifier U5 is also grounded through the second resistor R2, the inverting input terminal of the second operational amplifier U5 is grounded through the third resistor R3, a fourth resistor R4 is connected between the inverting input terminal and the output terminal of the second operational amplifier U5, and the output terminal of the second operational amplifier U5 is connected to the non-phase input terminal of the first operational amplifier U2 through the fifth resistor R5. The voltage output by the second voltage stabilizing chip U4 is divided by the first resistor R1 and the second resistor R2, and is input into the second operational amplifier U5. The third resistor R3 serves as a pull-down resistor at the inverting input terminal of the second operational amplifier U5. The fourth resistor R4 serves as a feedback resistor of the second operational amplifier U5. Through the protection and anti-interference function of the fifth resistor R5, the second operational amplifier U5 provides a positive bias voltage for the first operational amplifier U2. This bias can keep the output signal of the first operational amplifier U2 on the positive half axis when the input signal is zero or close to zero.

[0037] Reference Figure 2 It can be understood that the sampling voltage divider circuit 100 includes a plurality of resistors connected in series, and the two ends of the sixth resistor R6 of the sampling voltage divider circuit 100 close to the ground end are the voltage divider output ends of the sampling voltage divider circuit 100, and the end of the sixth resistor R6 close to the access side is connected to the first input end of the isolation amplifier U1, and the end of the sixth resistor R6 close to the ground end is connected to the second input end of the isolation amplifier U1. In the embodiment of the present application, the sampling voltage divider circuit 100 includes 3 resistors connected in series, the sixth resistor R6 is the third resistor, and the first input end and the second input end of the isolation amplifier U1 are respectively connected to the two ends of the third resistor of the sampling voltage divider circuit 100.

[0038] Reference Figure 2 It can be understood that the first input terminal of the isolation amplifier U1 is connected to one of the voltage-dividing output terminals of the sampling voltage-dividing circuit 100 through the seventh resistor R7, the second input terminal of the isolation amplifier U1 is connected to the other voltage-dividing output terminal of the sampling voltage-dividing circuit 100 through the eighth resistor R8, and the first capacitor C1 is connected between the seventh resistor R7 and the eighth resistor R8 and one end connected to the isolation amplifier U1. The seventh resistor R7, the eighth resistor R8 and the first capacitor C1 filter the voltage-dividing signal output by the sampling voltage-dividing circuit 100, filter out clutter signals, and improve the stability of signal transmission to the isolation amplifier circuit 200.

[0039] Continue to refer to Figure 2It can be understood that the non-inverting input terminal of the first operational amplifier U2 is connected to the first output terminal of the isolation amplifier U1 through the ninth resistor R9, the inverting input terminal of the first operational amplifier U2 is connected to the second output terminal of the isolation amplifier U1 through the tenth resistor R10, and the second capacitor C2 is connected between the ninth resistor R9 and the tenth resistor R10 and one end connected to the first operational amplifier U2. The ninth resistor R9, the tenth resistor R10 and the second capacitor C2 filter the output signal of the isolation amplifier U1, filter out the clutter signal, and improve the stability of the signal transmitted to the adjustable amplifier circuit 300.

[0040] Continue to refer to Figure 2 It can be understood that the output end of the first operational amplifier U2 is connected to the external controller 600 through the eleventh resistor R11, and the eleventh resistor R11 and the external controller 600 are grounded through the third capacitor C3. The eleventh resistor R11 and the third capacitor C3 filter the output signal of the first operational amplifier U2, improve the quality of the collected signal output to the controller 600, so as to be able to analyze the collected signal more accurately.

[0041] The isolated power supply circuit 400 of the present application provides power to the isolated amplifier circuit 200, the adjustable amplifier circuit 300 and the positive bias circuit. The isolated amplifier circuit 200 collects the input signal and couples and amplifies the gain m times through magnetic field induction. The adjustable amplifier circuit 300 further amplifies the signal amplified by the isolation amplifier circuit 200 by n times to reach the receiving voltage range of the main controller 600. The output signal gain is m*n, and it has the advantages of signal electrical isolation, adjustable gain, high precision, simple circuit, strong anti-interference ability, etc. The positive bias circuit provides a positive bias voltage to the adjustable amplifier circuit 300. This bias can keep the output signal on the positive half axis when the input signal is zero or close to zero.

[0042] In the second aspect, the present application further provides a circuit board, including a small signal sampling and amplifying circuit according to any one of the embodiments of the first aspect. The technical solution and technical effects of the small signal sampling and amplifying circuit have been described in detail above and will not be repeated here. By collecting the signal on the access side through the circuit board of the present application, the sampling signal can be electrically isolated, the amplification gain can be adjusted, and the sampling accuracy can be improved.

[0043] In a third aspect, the present application further provides a signal sampling device, comprising a circuit board according to any one of the embodiments of the second aspect. The signal sampling device collects signals from the access side, can electrically isolate the sampled signals, has adjustable amplification gain, and improves sampling accuracy.

[0044] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present application.

Claims

1. A small signal sampling and amplifying circuit, characterized in that: include: A sampling voltage divider circuit, one end of which is used to obtain a signal from the access side, and the other end of which is grounded; An isolation amplifier circuit, the isolation amplifier circuit comprising an isolation amplifier, a first input terminal and a second input terminal of the isolation amplifier being respectively connected to two voltage-dividing output terminals of the sampling voltage-dividing circuit; An adjustable amplifier circuit includes a first operational amplifier, a non-phase input terminal of the first operational amplifier is connected to a first output terminal of the isolation amplifier, an inverting input terminal of the first operational amplifier is connected to a second output terminal of the isolation amplifier, an adjustable resistor is connected between the inverting input terminal and the output terminal of the first operational amplifier, and the output terminal of the first operational amplifier is also used to connect to an external controller to sense the signal state of the access side.

2. The small signal sampling and amplifying circuit according to claim 1, characterized in that: It also includes an isolated power supply circuit, the input end of the isolated power supply circuit is used to connect to the power supply, and the output end of the isolated power supply circuit is respectively connected to the isolated amplifier circuit and the adjustable amplifier circuit.

3. The small signal sampling and amplifying circuit according to claim 2, characterized in that: The isolated power supply circuit includes a first voltage stabilizing chip and a second voltage stabilizing chip, the input end of the first voltage stabilizing chip is used to connect to the power supply, the first output end of the first voltage stabilizing chip is connected to the first power supply end of the isolation amplifier, the second output end of the first voltage stabilizing chip is connected to the input end of the second voltage stabilizing chip, and the output end of the second voltage stabilizing chip is respectively connected to the second power supply end of the isolation amplifier and the positive power supply end of the first operational amplifier.

4. The small signal sampling and amplifying circuit according to claim 3, characterized in that: It also includes a bias power supply circuit, which includes a second operational amplifier, a non-phase input terminal of the second operational amplifier is connected to the output terminal of the second voltage stabilizing chip through a first resistor, the non-phase input terminal of the second operational amplifier is also grounded through a second resistor, the inverting input terminal of the second operational amplifier is grounded through a third resistor, a fourth resistor is connected between the inverting input terminal and the output terminal of the second operational amplifier, and the output terminal of the second operational amplifier is connected to the non-phase input terminal of the first operational amplifier through a fifth resistor.

5. The small signal sampling and amplifying circuit according to claim 1, characterized in that: The sampling voltage divider circuit includes a plurality of resistors connected in series in sequence. The two ends of the sixth resistor of the sampling voltage divider circuit close to the ground end are the voltage divider output ends of the sampling voltage divider circuit. One end of the sixth resistor close to the access side is connected to the first input end of the isolation amplifier, and one end of the sixth resistor close to the ground end is connected to the second input end of the isolation amplifier.

6. The small signal sampling and amplifying circuit according to claim 1, characterized in that: The first input terminal of the isolation amplifier is connected to one of the voltage divider output terminals of the sampling voltage divider circuit through a seventh resistor, the second input terminal of the isolation amplifier is connected to the other voltage divider output terminal of the sampling voltage divider circuit through an eighth resistor, and a first capacitor is connected between the seventh resistor and one end of the eighth resistor connected to the isolation amplifier.

7. The small signal sampling and amplifying circuit according to claim 1, characterized in that: The non-inverting input terminal of the first operational amplifier is connected to the first output terminal of the isolation amplifier through a ninth resistor, the inverting input terminal of the first operational amplifier is connected to the second output terminal of the isolation amplifier through a tenth resistor, and a second capacitor is connected between the ninth resistor and one end of the tenth resistor connected to the first operational amplifier.

8. The small signal sampling and amplifying circuit according to claim 1, characterized in that: The output end of the first operational amplifier is connected to the external controller via an eleventh resistor, and the eleventh resistor and the external controller are grounded via a third capacitor.

9. A circuit board, characterized in that: It comprises the small signal sampling and amplifying circuit as claimed in any one of claims 1 to 8.

10. A signal sampling device, characterized in that: Comprising the circuit board as claimed in claim 9.

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