A voltage reference circuit, a circuit board, and an electronic device

Abstract

The application provides a voltage reference circuit, a circuit board and an electronic device, the voltage reference circuit comprising a voltage output unit and a current generation unit; the voltage output unit is configured to output a reference voltage according to a first current on the voltage output unit; the current generation unit comprises a first branch, a second branch and an operational amplifier, and the operational amplifier is configured to adjust the first current according to a second current on the first branch and a third current on the second branch; the application sets that the operational amplifier comprises a first transistor and a second transistor, and the first transistor and the second transistor are triodes, the base of the first transistor is connected with the first branch, and the base of the second transistor is connected with the second branch; that is, the first transistor and the second transistor are input pairs of the operational amplifier, which is conducive to reducing the noise of the reference voltage, and in particular, the 1 / f noise of the reference voltage can be reduced.

Description

Technical Field

[0001] This application belongs to the field of reference voltage design technology, and in particular relates to a voltage reference circuit, circuit board and electronic device. Background Technology

[0002] In integrated circuit chips, analog circuits such as ADC / DAC (analog-to-digital / digital-to-analog converters) and LDO (low-dropout linear regulators) require voltage reference circuits to provide a reference voltage.

[0003] However, in related technologies, voltage reference circuits include operational amplifiers, and these operational amplifiers contain a number of MOSFETs. However, the MOSFETs may cause the output voltage of the voltage reference circuit to become noisier, which will directly affect the stability of the application circuit.

[0004] Therefore, how to reduce the noise of the output voltage of a voltage reference circuit is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a voltage reference circuit, circuit board, and electronic device, which aims to solve the problem of high noise in the output voltage of voltage reference circuits in conventional technology.

[0006] A first aspect of this application provides a voltage reference circuit, the voltage reference circuit comprising:

[0007] A voltage output unit is configured to output a reference voltage based on a first current, wherein the first current is the current on the voltage output unit;

[0008] The current generating unit includes a first branch, a second branch, and an operational amplifier. The operational amplifier is connected to the first branch and the second branch and is used to adjust the first current according to the second current on the first branch and the third current on the second branch.

[0009] The operational amplifier includes a first transistor and a second transistor, a first MOSFET and a second MOSFET. The first transistor and the second transistor are bipolar transistors. The base of the first transistor is connected to the first branch, the base of the second transistor is connected to the second branch, the emitter of the first transistor is connected to the emitter of the second transistor, the collector of the first transistor is connected to the drain of the first MOSFET, the source of the first MOSFET is grounded, the collector of the second transistor is connected to the drain of the second MOSFET, the source of the second MOSFET is grounded, and the gate of the first MOSFET and the gate of the second MOSFET are connected.

[0010] In some embodiments of this application, the first branch includes a third transistor and a fourth transistor connected in series. The end of the third transistor away from the fourth transistor is connected to a first power supply, and the end of the fourth transistor away from the third transistor is grounded. The third transistor is a MOSFET, and the fourth transistor is a bipolar transistor.

[0011] The operational amplifier includes a first input terminal, which is connected between the third transistor and the fourth transistor.

[0012] In some embodiments of this application, the second branch includes a fifth transistor, a first resistor, and a sixth transistor connected in series. The end of the fifth transistor away from the first resistor is connected to the first power supply, and the end of the sixth transistor away from the first resistor is grounded. The fifth transistor is a MOSFET, and the sixth transistor is a transistor.

[0013] The operational amplifier includes a second input terminal, which is connected between the fifth transistor and the first resistor.

[0014] In some embodiments of this application, the voltage output unit includes a seventh transistor, a second resistor, and an eighth transistor connected in series. The end of the seventh transistor away from the second resistor is connected to the first power supply, and the end of the eighth transistor away from the first power supply is grounded. The seventh transistor is a MOSFET, and the eighth transistor is a transistor.

[0015] The voltage between the seventh transistor and the second resistor is the reference voltage.

[0016] In some embodiments of this application, the fourth transistor and the sixth transistor are bipolar transistors, and the bases of the fourth transistor and the sixth transistor are both connected to ground; the collector of the fourth transistor is connected to the third transistor, the emitter of the fourth transistor is grounded, the collector of the sixth transistor is connected to the first resistor, and the emitter of the sixth transistor is grounded.

[0017] And / or, the eighth transistor is a triode, the base of the eighth transistor is grounded, the collector of the eighth transistor is connected to the second resistor, and the emitter of the eighth transistor is grounded.

[0018] In some embodiments of this application, the operational amplifier includes a first output terminal connected to the gate of the third transistor, the gate of the fifth transistor, and the gate of the seventh transistor. The source of the third transistor is connected to a first power supply, and the drain of the third transistor is connected to the collector of the fourth transistor. The source of the fifth transistor is connected to the first power supply, and the drain of the fifth transistor is connected to the first resistor. The source of the seventh transistor is connected to the first power supply, and the drain of the seventh transistor is connected to the second resistor, so as to adjust the first current, the second current, and the third current.

[0019] In some embodiments of this application, the third transistor, the fifth transistor, and the seventh transistor are MOS transistors of the same model and size, so that the current intensities of the first current, the second current, and the third current are equal.

[0020] In some embodiments of this application, the current generating unit further includes a third resistor, one end of which is connected to the first input terminal, and the other end is connected between the third transistor and the fourth transistor;

[0021] The resistance value of the third resistor is equal to the resistance value of the first resistor.

[0022] In some embodiments of this application, the first input terminal is the negative input terminal of the operational amplifier, and the second input terminal is the positive input terminal of the operational amplifier.

[0023] Secondly, this application also provides a circuit board, the circuit board including a circuit board and the voltage reference circuit described above, the voltage reference circuit being integrated on the circuit board.

[0024] Thirdly, this application also provides an electronic device, which includes the circuit board described above.

[0025] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: In the voltage reference circuit, circuit board and electronic device described above, the voltage reference circuit includes a voltage output unit and a current generating unit; the voltage output unit is used to output a reference voltage according to a first current on the voltage output unit; the current generating unit includes a first branch, a second branch and an operational amplifier, the operational amplifier is used to adjust the first current according to a second current on the first branch and a third current on the second branch; the present application sets the operational amplifier to include a first transistor and a second transistor, and the first transistor and the second transistor are transistors, the base of the first transistor is connected to the first branch, and the base of the second transistor is connected to the second branch; that is, the first transistor and the second transistor are the input pair of the operational amplifier, which is beneficial to reduce the noise of the reference voltage, especially the 1 / f noise of the reference voltage. Attached Figure Description

[0026] Figure 1 A schematic diagram of the circuit structure of the operational amplifier in the related technology provided in this application;

[0027] Figure 2 A schematic diagram of the circuit structure of a voltage reference circuit provided in an embodiment of this application;

[0028] Figure 3 A schematic diagram of the circuit structure of an operational amplifier provided in an embodiment of this application;

[0029] Figure 4 A schematic diagram of the circuit structure of a voltage reference circuit provided in another embodiment of this application.

[0030] Specific element symbol explanations: 100 - Voltage output unit, 200 - Current generation unit, VDD1 - First power supply, VDD2 - Second power supply, MN1 - First MOSFET, MN2 - Second MOSFET, MN3 - Third MOSFET, MP1 - Third transistor, MP2 - Fifth transistor, MP3 - Seventh transistor, MP4 - Fourth MOSFET, MP5 - Fifth MOSFET, MP6 - Sixth MOSFET, MP7 - Seventh MOSFET, MP1 - First MOSFET, Q1 - Fourth transistor, Q2 - Sixth transistor, Q3 - Eighth transistor, Q4 - First transistor, Q5 - Second transistor, AMP - Operational amplifier, R1 - First resistor, R2 - Second resistor, R3 - Third resistor. Detailed Implementation

[0031] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0032] It should be noted that when a component is referred to as being "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0033] It should be understood that the terms "length", "width", "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0035] It should be noted that in many circuits, especially in integrated circuit chips, analog circuits such as ADCs / DACs (analog-to-digital converters) and LDOs (low-dropout linear regulators) require a voltage reference circuit to provide a reference voltage. However, noise in the reference voltage can affect circuit performance. Noise is generally divided into internal noise and external noise. Internal noise includes thermal noise and 1 / f noise (pink noise). Thermal noise is generally generated in resistors and can be filtered out using RC filters. However, 1 / f noise is frequency-dependent and is inherent noise of the reference source. 1 / f noise originates from surface defects in semiconductors and is difficult to filter out.

[0036] In related technologies, voltage reference circuits include operational amplifiers, which typically contain numerous MOSFETs. However, these MOSFETs can increase the noise in the output voltage of the voltage reference circuit, directly affecting the stability of the application circuit. For details, please refer to [link to relevant documentation]. Figure 1 , Figure 1 A schematic diagram of the operational amplifier structure provided in this application is shown; wherein, V- is the first input terminal of the operational amplifier, V+ is the second input terminal of the operational amplifier, and V0 is the first output terminal of the operational amplifier. The input transistors in this operational amplifier are all MOSFETs. Since the current in a MOSFET flows through the surface of the semiconductor structure, the MOSFET will generate extremely high 1 / f noise.

[0037] Based on this, this application improves the relevant voltage reference circuit, circuit board and electronic equipment.

[0038] Please refer to the following: Figure 2 and Figure 3 , Figure 2 A schematic diagram of the circuit structure of the voltage reference circuit provided in this embodiment is shown. Figure 3 A schematic diagram of the operational amplifier AMP provided in this embodiment is shown. In a voltage reference circuit of this embodiment, the voltage reference circuit includes a voltage output unit 100 and a current generation unit 200. It is understood that the voltage output unit 100 can be used to output voltage, and the current generation unit 200 can be used to generate current.

[0039] Specifically, the voltage output unit 100 is used to output a reference voltage based on a first current, where the first current is the current flowing through the voltage output unit 100. In other words, the voltage output unit 100 can output a reference voltage based on its own current.

[0040] The current generating unit 200 includes a first branch, a second branch, and an operational amplifier AMP. The operational amplifier AMP is connected to the first branch and the second branch and is used to adjust the first current based on the second current in the first branch and the third current in the second branch. That is, the first current is related to the second current and the third current, and the first current can be adjusted by adjusting the second current and the third current to adjust the reference voltage.

[0041] The operational amplifier AMP includes a first transistor Q4 and a second transistor Q5. Both transistors are bipolar junction transistors (BJTs), with the base of the first transistor Q4 connected to the first branch and the base of the second transistor Q5 connected to the second branch. In other words, the first transistor Q4 and the second transistor Q5 form the input pair of the operational amplifier AMP.

[0042] In current voltage reference circuits, the input transistors of the operational amplifier (AMP) are all MOSFETs, which have relatively high 1 / f noise. However, in this application, by setting the first transistor Q4 and the second transistor Q5 as the input transistors of the operational amplifier (AMP), and by using both transistors as bipolar transistors (BJTs), the current in the BJTs flows through the substrate. Compared to the current flowing through the surface in a MOSFET, the technical solution of this application has lower 1 / f noise, thereby helping to reduce the noise of the reference voltage.

[0043] In one exemplary description, please refer to... Figure 1 The operational amplifier AMP in the related technology includes a first MOSFET MP1MN1, a second MOSFET MN2, a third MOSFET MN3, a fourth MOSFET MP4, a fifth MOSFET MP5, a sixth MOSFET MP6, and a seventh MOSFET MP7. Among them, the sixth MOSFET MP6 and the seventh MOSFET MP7 are the input pair transistors of the operational amplifier AMP.

[0044] Specifically, the first MOSFET MP1MN1, the second MOSFET MN2, and the third MOSFET MN3 are N-channel field-effect transistors. The fourth MOSFET MP4, the fifth MOSFET MP5, the sixth MOSFET MP6, and the seventh MOSFET MP7 are P-channel field-effect transistors.

[0045] More specifically, the drain of the sixth MOSFET MP6 is connected to the drain of the first MOSFET MP1MN1, the gate of the sixth MOSFET MP6 is connected to the first branch, and the source of the sixth MOSFET MP6 and the source of the seventh MOSFET MP7 are both connected to the drain of the fourth MOSFET MP4; the gate of the seventh MOSFET MP7 is connected to the second branch, and the drain of the seventh MOSFET MP7 is connected to the drain of the second MOSFET MN2; the source of the first MOSFET MP1MN1 and the source of the second MOSFET MN2 are both connected to ground, and the gate of the first MOSFET MP1MN1 and the gate of the second MOSFET MN2 are both connected between the drain of the first MOSFET MP1MN1 and the drain of the sixth MOSFET MP6.

[0046] The drain of the third MOSFET MN3 is connected to the drain of the fifth MOSFET MP5. The source of the third MOSFET MN3 is grounded. The gate of the third MOSFET MN3 is connected between the drain of the second MOSFET MN2 and the drain of the seventh MOSFET MP7. The sources of the fourth MOSFET MP4 and the fifth MOSFET MP5 are both connected to the second power supply VDD2. The gates of the fourth MOSFET MP4 and the fifth MOSFET MP5 are connected together between the drain of the fifth MOSFET MP5 and the drain of the third MOSFET MN3.

[0047] It is understood that in this application, the sixth MOS transistor MP6 is replaced with the first transistor Q4, and the seventh MOS transistor MP7 is replaced with the second transistor Q5. Both the first transistor Q4 and the second transistor Q5 are PNP transistors, in order to eliminate the 1 / f noise generated by the operational amplifier AMP.

[0048] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the first branch includes a third transistor MP1 and a fourth transistor Q1 connected in series. The end of the third transistor MP1 away from the fourth transistor Q1 is connected to the first power supply VDD1, and the end of the fourth transistor Q1 away from the third transistor MP1 is grounded. The operational amplifier AMP includes a first input terminal, which is connected between the third transistor MP1 and the fourth transistor Q1.

[0049] It should be noted that an operational amplifier (AMP) typically has two signal input terminals and one signal output terminal. One of the signal input terminals is connected between the third transistor MP1 and the fourth transistor Q1, and the first current can be adjusted by adjusting the on / off state of the third transistor MP1, thereby adjusting the input signal of the first input terminal.

[0050] In some embodiments, the third transistor MP1 is a P-channel MOSFET, and the fourth transistor Q1 is a PNP transistor. The voltage at the first input terminal can be directly equivalent to the voltage VBE1 across the fourth transistor Q1.

[0051] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the second branch includes a fifth transistor MP2, a first resistor R1, and a sixth transistor Q2 connected in series. The end of the fifth transistor MP2 furthest from the first resistor R1 is connected to a first power supply VDD1, and the end of the sixth transistor Q2 furthest from the first resistor R1 is grounded. The operational amplifier AMP includes a second input terminal, which is connected between the fifth transistor MP2 and the first resistor R1.

[0052] It should be noted that the other input terminal of the operational amplifier AMP is connected between the fifth transistor MP2 and the first resistor R1, and the second current can be adjusted by adjusting the on / off state of the fifth transistor MP2, thereby adjusting the input signal of the second input terminal.

[0053] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the first input terminal is the negative input terminal of the operational amplifier AMP, and the second input terminal is the positive input terminal of the operational amplifier AMP.

[0054] In some embodiments, the fifth transistor MP2 is a P-channel MOSFET, and the sixth transistor Q2 is a PNP transistor. The voltage at the second input terminal can be directly equivalent to the voltage VBE2 across the sixth transistor Q2 and the voltage I1*R1 across the first resistor R1. Here, I1 is the current value of the third current in the second branch, and R1 is the resistance value of the first resistor R1.

[0055] Please refer to the embodiments described in this application. Figure 2 The voltage output unit 100 in this embodiment includes a seventh transistor MP3, a second resistor R2 and an eighth transistor Q3 connected in series. The end of the seventh transistor MP3 away from the second resistor R2 is connected to the first power supply VDD1, and the end of the eighth transistor Q3 away from the first power supply VDD1 is grounded. The voltage between the seventh transistor MP3 and the second resistor R2 is a reference voltage.

[0056] It should be noted that the external circuit can obtain the reference voltage by directly connecting it between the seventh transistor MP3 and the second resistor R2.

[0057] In some embodiments, the seventh transistor MP3 is a P-channel MOSFET, and the eighth transistor Q3 is a PNP transistor. It can be obtained that... Where VREF is the reference voltage value, I2 is the first current value on the voltage output unit 100, R2 is the resistance value of the second resistor R2, and V BE3 This is the voltage across the eighth transistor Q3.

[0058] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the fourth transistor Q1 and the sixth transistor Q2 are transistors, and the bases of the fourth transistor Q1 and the sixth transistor Q2 are connected to ground; the eighth transistor Q3 is a transistor, and the base of the eighth transistor Q3 is grounded.

[0059] Please refer to the embodiments described in this application. Figure 2 The operational amplifier AMP in this embodiment includes a first output terminal, which is connected to a third transistor MP1, a fifth transistor MP2, and a seventh transistor MP3 to adjust the first current, the second current, and the third current.

[0060] It's important to explain that the operational amplifier (AMP) has a clamping function. When the voltages at the first and second input terminals are unequal, it adjusts the output signal at the first output terminal to equalize the voltages at the first and second input terminals, thus achieving voltage clamping between them. However, the second current is related to the voltage at the first input terminal, the third current is related to the voltage at the second input terminal, and the voltage at the first output terminal is related to the first current. Therefore, it can be understood that the first current is adjusted based on the third and second currents.

[0061] Please refer to the embodiments described in this application. Figure 2 In this embodiment, the third transistor MP1, the fifth transistor MP2, and the seventh transistor MP3 are MOSFETs of the same model and size, so that the current intensities of the first current, the second current, and the third current are equal. That is, the first current, the second current, and the third current can all be equivalently replaced by I2.

[0062] Please refer to the embodiments described in this application. Figure 2 The current generating unit 200 in this embodiment also includes a third resistor R3. One end of the third resistor R3 is connected to the first input terminal, and the other end is connected between the third transistor MP1 and the fourth transistor Q1. The resistance value of the third resistor R3 is equal to the resistance value of the first resistor R1.

[0063] It should be explained that replacing the input transistors in the operational amplifier (AMP) with transistors, while reducing 1 / f noise, also leads to a decrease in the accuracy of the reference voltage. Setting a third resistor, R3, helps to reduce the impact of the transistors on accuracy in the AMP. Furthermore, when the resistance value of the third resistor R3 is equal to that of the first resistor R1, the impact of the transistors on accuracy in the AMP can be eliminated.

[0064] In some exemplary descriptions, please refer to Figure 4 , Figure 4 This is a schematic diagram of the circuit structure of a voltage reference circuit provided in an embodiment of this application. In this embodiment, the high gain of an operational amplifier is utilized to... Figure 1 The potentials at points A and B are clamped to the same voltage value. Assume the ratio of the emitter junction areas of the fourth transistor Q1 and the sixth transistor Q2 is 1:N.

[0065] When the input transistors in the operational amplifier AMP are MOSFETs, then the first current, the second current, and the third current can all be expressed as: Among them, V T This is the thermoelectric potential. Therefore, the reference voltage can be obtained as: .

[0066] When the input pair of transistors in the operational amplifier (AMP) is a bipolar transistor, we can obtain , among which, I b This represents the base current of the transistor in the operational amplifier AMP. Therefore, the reference voltage can be obtained as: It can be seen that the reference voltage is affected by the base current of the transistor.

[0067] In the embodiments of this application, after connecting the third resistor R3 to the first input terminal, when the input transistors in the operational amplifier AMP are transistors, the influence of the transistor base current on the reference voltage can be reduced. Specifically, since the voltages at the first and second input terminals of the operational amplifier AMP are equal, it can be obtained that: After conversion, we can get ;because Therefore, combining them, we can obtain: It needs to be explained that the influence of the transistor's base current on the reference voltage can be reduced by adjusting the resistance values ​​of the first resistor R1 and the third resistor R3. Furthermore, when the resistance values ​​of the first resistor R1 and the third resistor R3 are equal, I... b The coefficient is 0, which can eliminate the influence of the transistor base current on the reference voltage and help improve the accuracy of the reference voltage.

[0068] Furthermore, in order to better implement the voltage reference circuit of this application, based on the voltage reference circuit provided in any of the above embodiments, this application also provides a circuit board, which includes a circuit board and the voltage reference circuit in any of the above embodiments, wherein the voltage reference circuit is integrated on the circuit board.

[0069] In some embodiments, the circuit board can be applied to high-precision devices such as medical devices, data acquisition devices, and temperature / pressure sensor devices to improve the accuracy and sensitivity of such high-precision devices.

[0070] Furthermore, in order to better implement the circuit board of this application, based on the circuit board provided in any of the above embodiments, this application also provides an electronic device that includes the circuit board of any of the above embodiments.

[0071] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0072] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0073] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0074] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0075] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A voltage reference circuit, characterized in that, The voltage reference circuit includes: A voltage output unit is configured to output a reference voltage based on a first current, wherein the first current is the current on the voltage output unit; The current generating unit includes a first branch, a second branch, and an operational amplifier. The operational amplifier is connected to the first branch and the second branch and is used to adjust the first current according to the second current on the first branch and the third current on the second branch. The operational amplifier includes a first transistor and a second transistor, a first MOS transistor and a second MOS transistor. The first transistor and the second transistor are bipolar transistors. The base of the first transistor is connected to the first branch, the base of the second transistor is connected to the second branch, the emitter of the first transistor is connected to the emitter of the second transistor, the collector of the first transistor is connected to the drain of the first MOS transistor, the source of the first MOS transistor is grounded, the collector of the second transistor is connected to the drain of the second MOS transistor, the source of the second MOS transistor is grounded, and the gate of the first MOS transistor and the gate of the second MOS transistor are connected. The first branch includes a third transistor and a fourth transistor connected in series. The end of the third transistor away from the fourth transistor is connected to a first power supply, and the end of the fourth transistor away from the third transistor is grounded. The third transistor is a MOSFET, and the fourth transistor is a bipolar transistor. The operational amplifier includes a first input terminal, which is connected between the third transistor and the fourth transistor. The second branch includes a fifth transistor, a first resistor, and a sixth transistor connected in series. The end of the fifth transistor away from the first resistor is connected to the first power supply, and the end of the sixth transistor away from the first resistor is grounded. The fifth transistor is a MOSFET, and the sixth transistor is a transistor. The operational amplifier includes a second input terminal, which is connected between the fifth transistor and the first resistor. The voltage output unit includes a seventh transistor, a second resistor, and an eighth transistor connected in series. The end of the seventh transistor away from the second resistor is connected to the first power supply, and the end of the eighth transistor away from the first power supply is grounded. The seventh transistor is a MOSFET, and the eighth transistor is a transistor. Wherein, the voltage between the seventh transistor and the second resistor is the reference voltage; The current generating unit further includes a third resistor, one end of which is connected to the first input terminal, and the other end of which is connected between the third transistor and the fourth transistor; The resistance value of the third resistor is equal to the resistance value of the first resistor.

2. The voltage reference circuit according to claim 1, characterized in that, The base of the fourth transistor and the base of the sixth transistor are both connected to ground. The collector of the fourth transistor is connected to the third transistor, and the emitter of the fourth transistor is grounded. The collector of the sixth transistor is connected to the first resistor, and the emitter of the sixth transistor is grounded. And / or, the base of the eighth transistor is grounded, the collector of the eighth transistor is connected to the second resistor, and the emitter of the eighth transistor is grounded.

3. The voltage reference circuit according to claim 1, characterized in that, The operational amplifier includes a first output terminal, which is connected to the gate of the third transistor, the gate of the fifth transistor, and the gate of the seventh transistor. The source of the third transistor is connected to a first power supply, and the drain of the third transistor is connected to the collector of the fourth transistor. The source of the fifth transistor is connected to the first power supply, and the drain of the fifth transistor is connected to the first resistor. The source of the seventh transistor is connected to the first power supply, and the drain of the seventh transistor is connected to the second resistor, so as to adjust the first current, the second current, and the third current.

4. The voltage reference circuit according to claim 3, characterized in that, The third transistor, the fifth transistor, and the seventh transistor are MOS transistors of the same model and size, so that the current intensities of the first current, the second current, and the third current are equal.

5. The voltage reference circuit according to claim 1, characterized in that, The first input terminal is the negative input terminal of the operational amplifier, and the second input terminal is the positive input terminal of the operational amplifier.

6. A circuit board, characterized in that, The circuit board includes a circuit board and a voltage reference circuit as described in any one of claims 1 to 5, wherein the voltage reference circuit is integrated on the circuit board.

7. An electronic device, characterized in that, The electronic device includes the circuit board as described in claim 6.

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