Bandgap reference circuit and image sensor

Abstract

The application provides a band gap reference circuit and an image sensor, which comprise a voltage compression module and a voltage difference module; the voltage compression module is used for generating a first voltage which is inversely proportional to absolute temperature, and performing compression adjustment on the first voltage to obtain a second voltage; and the voltage difference module is used for generating a third voltage which is proportional to absolute temperature, and performing summation on the second voltage and the third voltage to obtain a reference voltage which is independent of temperature. The first voltage which is inversely proportional to absolute temperature is compressed by the voltage compression module to obtain the second voltage, and the second voltage which is inversely proportional to absolute temperature and the third voltage which is proportional to absolute temperature are summed by the voltage difference module to obtain the reference voltage. In this way, by adjusting the functions of the circuit modules, the circuit area and power consumption are effectively reduced, the precision of the reference voltage is improved, and the problems of large circuit area and high power consumption of the existing band gap reference circuit are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a bandgap reference circuit and an image sensor. Background Art

[0002] A bandgap reference voltage is the sum of a voltage with a positive temperature coefficient and a voltage with a negative temperature coefficient. Because the temperature coefficients of these two voltages cancel each other out, a temperature-independent voltage reference is obtained. For silicon-based materials, this voltage is approximately 1.2V. Many analog circuit modules require a bandgap reference voltage.

[0003] With the development of integrated circuit technology, the existing bandgap reference circuit is usually based on the characteristics of silicon material bandgap voltage independent of power supply voltage and temperature, using the emitter bias difference between two bipolar transistors. The positive temperature coefficient of another bipolar transistor is biased at the emitter The negative temperature coefficients of the reference voltage cancel each other out, achieving low temperature drift and high precision. It can be expressed as , where a represents the amplification factor through the resistor network.

[0004] However, existing bandgap reference circuits require at least three groups of transistors to coordinate and adjust the temperature coefficient, and correspondingly require multiple MOS transistors to adjust the current flowing through the transistors, resulting in a large circuit area, high power consumption, and difficulty in controlling accuracy. Summary of the Invention

[0005] An object of the present invention is to provide a bandgap reference circuit and an image sensor, so as to at least solve the problems of large area and high power consumption of the existing bandgap reference circuit.

[0006] To solve the above technical problems, the present invention provides a bandgap reference circuit, comprising a voltage doubling module and a voltage difference module; the voltage doubling module is used to generate a first voltage that is inversely proportional to the absolute temperature, and to multiply and adjust the first voltage to obtain a second voltage; the voltage difference module is used to generate a third voltage that is proportional to the absolute temperature, and to sum the second and third voltages to obtain a reference voltage that is independent of temperature.

[0007] Optionally, in the bandgap reference circuit, the voltage multiplication module includes a negative temperature coefficient voltage generation unit and a voltage divider unit; the negative temperature coefficient voltage generation unit is used to generate the first voltage which is inversely proportional to the absolute temperature; and the voltage divider unit is used to multiply the first voltage to obtain the second voltage.

[0008] Optionally, in the bandgap reference circuit, the negative temperature coefficient voltage generating unit includes a first transistor, and the voltage dividing unit includes a first resistor and a second resistor;

[0009] The gate and drain of the first transistor are connected and connected to a current source, and the source of the first transistor is grounded; the first end of the first resistor is connected to the current source; the second end of the first resistor is connected to the first end of the second resistor and to the drain of the first transistor; the second end of the second resistor is grounded; wherein the drain of the first transistor generates the first voltage, and the first end of the first resistor generates the second voltage.

[0010] Optionally, in the bandgap reference circuit, the first transistor is a single MOS transistor operating in a subthreshold region.

[0011] Optionally, in the bandgap reference circuit, the resistance of the first resistor is smaller than the resistance of the second resistor.

[0012] Optionally, in the bandgap reference circuit, the voltage multiplication module also includes a first op amp; the first input terminal of the first op amp is connected to the drain of the first transistor, the second input terminal of the first op amp is connected to the output terminal of the first op amp, and the output terminal of the first op amp is connected to the second terminal of the first resistor.

[0013] Optionally, in the bandgap reference circuit, the voltage difference module includes a voltage stabilization and noise filtering unit and a positive temperature coefficient voltage generation unit; the voltage stabilization and noise filtering unit is used to perform voltage stabilization and noise filtering on the second voltage, and transmit the second voltage after voltage stabilization and noise filtering to the positive temperature coefficient voltage generation unit; the positive temperature coefficient voltage generation unit is used to generate the third voltage that is proportional to the absolute temperature, and sum the second voltage and the third voltage to obtain a reference voltage that is independent of temperature.

[0014] Optionally, in the bandgap reference circuit, the voltage stabilization and noise filtering unit includes a second operational amplifier, and the positive temperature coefficient voltage generating unit includes a second transistor;

[0015] The first input terminal of the second op amp is connected to the second voltage, the second input terminal of the second op amp is connected to the output terminal of the second op amp, and the output terminal of the second op amp is connected to the gate of the second transistor; the drain of the second transistor is connected to the gate and connected to the second voltage, and the source of the second transistor is connected to the current source and outputs a reference voltage.

[0016] Optionally, in the bandgap reference circuit, the second transistor is a plurality of parallel MOS transistors operating in a subthreshold region.

[0017] Optionally, in the bandgap reference circuit, the voltage difference module also includes a current mirror; the current mirror includes a third transistor and a fourth transistor; the drain of the third transistor is connected to the gate and connected to the current source, and the gate of the third transistor is connected to the gate of the fourth transistor; the drain of the fourth transistor is connected to the source of the second transistor; the source of the third transistor and the source of the fourth transistor are both grounded.

[0018] In order to solve the above technical problems, the present invention further provides an image sensor, comprising the bandgap reference circuit as described in any one of the above items.

[0019] The bandgap reference circuit and image sensor provided by the present invention include a voltage multiplication module and a voltage difference module. The voltage multiplication module is used to generate a first voltage inversely proportional to the absolute temperature and multiply and adjust the first voltage to obtain a second voltage. The voltage difference module is used to generate a third voltage directly proportional to the absolute temperature and sum the second and third voltages to obtain a temperature-independent reference voltage. The voltage multiplication module multiplies the first voltage inversely proportional to the absolute temperature to obtain the second voltage, and the voltage difference module sums the second voltage inversely proportional to the absolute temperature and the third voltage directly proportional to the absolute temperature to obtain the reference voltage. Thus, by adjusting the functions of the circuit modules, the circuit area and power consumption are effectively reduced, the accuracy of the reference voltage is improved, and the problems of large area and high power consumption of existing bandgap reference circuits are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a circuit schematic diagram of an existing bandgap reference circuit;

[0021] Figure 2 A block diagram of the module structure of the bandgap reference circuit provided in this embodiment;

[0022] Figure 3 A block diagram of the unit structure of the bandgap reference circuit provided in this embodiment;

[0023] Figure 4 A circuit schematic diagram of a bandgap reference circuit provided in this embodiment;

[0024] Figure 5 A block diagram of the unit structure of the high-precision bandgap reference circuit provided in this embodiment;

[0025] Figure 6 This is a circuit schematic diagram of the high-precision bandgap reference circuit provided in this embodiment. DETAILED DESCRIPTION

[0026] The bandgap reference circuit and image sensor proposed in the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all simplified and not precisely scaled, and are only used to facilitate and clearly illustrate the embodiments of the present invention. Furthermore, the structures shown in the drawings are often portions of actual structures. In particular, different drawings may require different emphasis and may use different scales.

[0027] It should be noted that the terms "first", "second", etc. in the specification, claims, and accompanying drawings of the present invention are used to distinguish similar objects in order to describe the embodiments of the present invention, and are not used to describe a specific order or sequence. It should be understood that the structures used in this way can be interchanged under appropriate circumstances. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products, or apparatuses.

[0028] The reference voltage provided by the existing bandgap reference circuit is mainly based on the physical property that the energy difference (bandgap) between the conduction band and the valence band of silicon material is about 1.17eV at 0K and about 1.1eV at room temperature (300K). It is obtained by considering comprehensive factors such as temperature compensation requirements and process adaptation. The corresponding circuit schematic is shown in the figure below. Figure 1 As shown, it includes three transistors (triodes) Q01, Q02 and Q03, three MOS tubes M01, M02 and M03, an operational amplifier B01 and two resistors R01 and R02, wherein Q02 is composed of n parallel unit transistors (typically, n=8, 15, 24), and Q01 and Q03 are single unit transistors.

[0029] Specifically, such as Figure 1 As shown, the sources of the three MOS transistors M01, M02 and M03 are all connected to the power supply VDD, and the gates are connected to each other and to the output terminal Vout of the operational amplifier B01; the drain of M01 is connected to the emitter of the transistor Q01 and the first input terminal Vin_n of the operational amplifier B01; the drain of M02 is connected to the second input terminal Vin_p of the operational amplifier B01 and to the emitter of the transistor Q02 through the resistor R01; the drain of M02 is connected to the emitter of the transistor Q03 through the resistor R02, and the reference voltage Vref is drawn at the drain; the bases and collectors of the three transistors Q01, Q02 and Q03 are all grounded.

[0030] The existing bandgap reference circuit can adjust the size of the three MOS transistors M01, M02 and M03 so that the current flowing through the three transistors Q01, Q02 and Q03 is the same. First, the voltage with a negative temperature coefficient is obtained by the transistor Q01. , see Figure 1 , the voltage at the X node is , due to the “virtual short” of operational amplifier B01, the voltages at the X and Y nodes are the same, that is, the voltage at the Y node is also At the same time, due to the presence of transistor Q02, there is a voltage difference between the two ends of resistor R01 , this voltage difference has a positive temperature coefficient. At this time, the current with a positive temperature coefficient in the branch where resistor R01 is located can be calculated; then, through the current mirror formed by the upper MOS transistors M02 and M03, this current with a positive temperature coefficient is copied to the branch where resistor R02 is located; finally, by adjusting the resistance values ​​of resistors R01 and R02, a reference voltage Vref that is independent of temperature can be obtained.

[0031] Among them, the current with positive temperature coefficient (PTAT) in the branch where resistor R01 is located can be expressed as:

[0032]

[0033] The reference voltage output by the bandgap reference circuit can be expressed as:

[0034]

[0035] It can be seen from this that the reference voltage output by the existing bandgap reference circuit is a voltage with a negative temperature coefficient. The voltage difference with the multiplied positive temperature coefficient sum.

[0036] However, existing bandgap reference circuits require at least three groups of transistors to coordinate and adjust the temperature coefficient, and correspondingly require multiple MOS transistors to adjust the current flowing through the transistors, resulting in a large circuit area, high power consumption, and difficulty in controlling accuracy.

[0037] To solve this problem, this embodiment provides a bandgap reference circuit, such as Figure 2 As shown, it includes a voltage doubling module and a voltage difference module; the voltage doubling module is used to generate a first voltage inversely proportional to the absolute temperature, and multiply and adjust the first voltage to obtain a second voltage; the voltage difference module is used to generate a third voltage proportional to the absolute temperature, and sum the second voltage and the third voltage to obtain a reference voltage that is independent of temperature.

[0038] The bandgap reference circuit provided in this embodiment uses a voltage multiplication module to multiply a first voltage inversely proportional to the absolute temperature to obtain a second voltage, and uses a voltage difference module to sum the second voltage inversely proportional to the absolute temperature and a third voltage proportional to the absolute temperature to obtain a reference voltage. In this way, by adjusting the functions of the circuit modules, the circuit area and power consumption are effectively reduced, the accuracy of the reference voltage is improved, and the problems of large area and high power consumption of existing bandgap reference circuits are solved.

[0039] Specifically, in this embodiment, Figure 3 and Figure 5 As shown, the bandgap reference circuit provided by this embodiment further includes a current source module, and the current source module is used to provide a current source to the voltage multiplication module and the voltage difference module.

[0040] In practical applications, in this embodiment, if Figure 4 and Figure 6 As shown, the current source module includes multiple current sources to provide a current source Ix to each branch, wherein the current Ix provided by each current source is consistent.

[0041] Furthermore, in this embodiment, Figure 3 As shown, the voltage doubling module includes a negative temperature coefficient voltage generating unit and a voltage dividing unit; the negative temperature coefficient voltage generating unit is used to generate the first voltage which is inversely proportional to the absolute temperature; the voltage dividing unit is used to multiply the first voltage to obtain the second voltage.

[0042] Specifically, in this embodiment, the negative temperature coefficient voltage generating unit includes a first transistor Q1 , and the voltage dividing unit includes a first resistor R1 and a second resistor R2 .

[0043] like Figure 4 As shown, the gate and drain of the first transistor Q1 are connected and connected to the current source Ix, and the source of the first transistor Q1 is grounded; the first end of the first resistor R1 is connected to the current source Ix; the second end of the first resistor R1 is connected to the first end of the second resistor R2 and to the drain of the first transistor Q1; the second end of the second resistor R2 is grounded; wherein the drain of the first transistor Q1 generates the first voltage , the first end of the first resistor R1 generates the second voltage .

[0044] In practical applications, the first transistor Q1 can be a triode, the same as in the prior art. However, in this embodiment, to reduce the area and power consumption of the bandgap reference circuit, the first transistor Q1 is a single MOS transistor operating in the subthreshold region, specifically, a single NMOS transistor.

[0045] Preferably, in scenarios where circuit area or power consumption is not a big requirement, such as Figure 5 As shown, the voltage doubling module may further include a first operational amplifier.

[0046] Specifically, in this embodiment, Figure 6 As shown, the first input terminal Vin_p of the first operational amplifier B1 is connected to the drain of the first transistor Q1, the second input terminal Vin_n of the first operational amplifier B1 is connected to its output terminal Vout, and the output terminal Vout of the first operational amplifier B1 is connected to the second end of the first resistor R1.

[0047] In this embodiment, the first operational amplifier B1 is added to act as a buffer clamp, thereby effectively preventing voltage jitter and achieving high-precision control of the bandgap reference circuit.

[0048] In practical applications, the first operational amplifier B1 may be a unity-gain operational amplifier.

[0049] Furthermore, in this embodiment, Figure 3 As shown, the voltage difference module includes a voltage stabilization and noise filtering unit and a positive temperature coefficient voltage generation unit; the voltage stabilization and noise filtering unit is used to perform voltage stabilization and noise filtering on the second voltage, and transmit the second voltage after voltage stabilization and noise filtering to the positive temperature coefficient voltage generation unit; the positive temperature coefficient voltage generation unit is used to generate the third voltage that is proportional to the absolute temperature, and sum the second voltage and the third voltage to obtain a reference voltage that is independent of temperature.

[0050] Specifically, in this embodiment, the voltage stabilization and noise filtering unit includes a second operational amplifier B2, and the positive temperature coefficient voltage generating unit includes a second transistor Q2.

[0051] like Figure 4 and Figure 6 As shown, the first input terminal Vin_p of the second operational amplifier B2 is connected to the second voltage The second input terminal Vin_n of the second operational amplifier B2 is connected to its output terminal Vout, and the output terminal Vout of the second operational amplifier B2 is connected to the gate of the second transistor Q2; the drain of the second transistor Q2 is connected to the gate and is connected to the second voltage The source of the second transistor Q2 is connected to the current source Ix and outputs the reference voltage Vref.

[0052] In practical applications, the second transistor Q2 can be a triode, as in the prior art. However, in this embodiment, to reduce the area and power consumption of the bandgap reference circuit, the second transistor Q2 is a plurality of parallel-connected MOS transistors operating in the subthreshold region, specifically, a plurality of parallel-connected NMOS transistors.

[0053] Furthermore, in practical applications, the size of the unit transistors of the first transistor Q1 and the size of each unit transistor of the second transistor Q2 are the same, and both the first transistor Q1 and the second transistor Q2 operate in the subthreshold region. In this way, not only can the first transistor Q1 operating in the subthreshold region be used to generate a first voltage inversely proportional to the absolute temperature, , it is also possible to use the first transistor Q1 and the second transistor Q2 working in the subthreshold region to work together to generate a third voltage proportional to the absolute temperature At the same time, since the first transistor Q1 and the second transistor Q2 operate in the subthreshold region, it is possible to ensure that the current in each branch is not too large, thereby effectively reducing the power consumption of the bandgap reference circuit.

[0054] In this embodiment, the second operational amplifier B2 is used as a buffer clamp, thereby effectively preventing voltage jitter, thereby achieving high-precision control of the bandgap reference circuit.

[0055] In practical applications, the second operational amplifier B2 may also be a unity-gain operational amplifier.

[0056] Furthermore, in order to ensure that each branch has the same current Ix, in this embodiment, Figure 5 As shown, the voltage difference module also includes a current mirror.

[0057] Specifically, in this embodiment, Figure 6 As shown, the current mirror includes a third transistor M1 and a fourth transistor M2; the drain of the third transistor M1 is connected to the gate and is connected to the current source Ix, and the gate of the third transistor M1 is connected to the gate of the fourth transistor M2; the drain of the fourth transistor M2 is connected to the source of the second transistor Q2; the source of the third transistor M1 and the source of the fourth transistor M2 are both grounded.

[0058] In this embodiment, the replication ratio of the current mirror is 1:1, so that the current connected to the source of the second transistor Q2 is Ix.

[0059] Of course, in other embodiments, current mirrors with other structures may also be used, and this application does not limit this.

[0060] In practical applications, both the third transistor M1 and the fourth transistor M4 may be MOS transistors, specifically, NMOS transistors.

[0061] The following, combined Figure 6 , the working principle of the bandgap reference circuit provided by this embodiment is explained.

[0062] When the bandgap reference circuit provided by this embodiment is in operation, the current source provides the current Ix. Figure 6 At the X node, a first voltage inversely proportional to absolute temperature (CTAT) can be obtained. At this time, due to the clamping of the first op amp B1, the voltage of the D node is also the first voltage Afterwards, the voltage of the Y node, ie the second voltage, is obtained through the resistor network composed of resistors R1 and R2. , the second voltage It can be expressed as:

[0063]

[0064] At node Z, we have:

[0065]

[0066] in, represents the gate-source voltage of the first transistor Q1, represents the gate-source voltage of the second transistor Q2, Indicates the reference voltage.

[0067] Through the clamping of the second op amp B2, the voltage at the Y node is equal to the voltage at the Z node, so:

[0068]

[0069] Since the first voltage Inversely proportional to absolute temperature (CTAT), the third voltage Proportional to absolute temperature (PTAT), so in order to obtain a reference voltage that is independent of temperature , the first voltage is required The resistance of the first resistor R1 needs to be smaller than the resistance of the second resistor R2 (R1<R2).

[0070] Finally, the reference voltage of the bandgap reference circuit provided by this embodiment is obtained for:

[0071]

[0072] The partial derivative of the above formula with respect to temperature is:

[0073]

[0074] From this we can see that By choosing a suitable ratio, we can make =0, thus obtaining a reference voltage that is independent of temperature.

[0075] Similarly, for Figure 4 As shown, the voltage doubling module does not have the first op amp B1, and the voltage at the X node is the first voltage that is inversely proportional to the absolute temperature (CTAT). Afterwards, the voltage of the Y node, ie the second voltage, is obtained through the resistor network composed of resistors R1 and R2. The specific analysis process is consistent with the above process, and this application will not go into details.

[0076] The existing bandgap reference circuit is a voltage proportional to absolute temperature (PTAT). Multiply it and then compare it with the voltage of CTAT (inversely proportional to absolute temperature) The sum is obtained by adding the reference voltage which is independent of temperature. The bandgap reference circuit provided in this embodiment is a voltage which is inversely proportional to the absolute temperature (CTAT). The voltage is then multiplied by the PTAT (proportional to absolute temperature) The sum is performed to obtain a temperature-independent reference voltage. In this way, the circuit structure can be effectively optimized, thereby reducing the circuit area and power consumption.

[0077] At the same time, in the bandgap reference circuit provided in this embodiment, since the first transistor Q1 and the second transistor Q2 are MOS transistors in the subthreshold region, the circuit area and power consumption can be further reduced.

[0078] Furthermore, the bandgap reference circuit provided in this embodiment, by adding the first operational amplifier B1 and the second operational amplifier B2, can utilize the buffer clamping function thereof to prevent voltage jitter and achieve high-precision voltage control.

[0079] This embodiment further provides an image sensor, including the above-mentioned bandgap reference circuit provided by this embodiment.

[0080] Since the bandgap reference circuit provided in this embodiment is based on silicon-based materials and can accurately provide a reference voltage lower than 1.2V, and has a small circuit area, low static power consumption, high stability and response speed, it can fully meet the needs of image sensors and thus be applied in the field of image sensors.

[0081] At the same time, since the bandgap reference circuit provided in this embodiment can be manufactured in a compatible CMOS process, it can be fully adapted to the CIS image sensor, thereby improving the integration of the image sensor.

[0082] Of course, the bandgap reference circuit provided in this embodiment is not limited to image sensors, and can be applied to any integrated circuit or chip that requires a reference voltage, and this application does not impose any limitation on this.

[0083] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In addition, the different parts between the various embodiments can also be used in combination with each other, and the present invention is not limited to this.

[0084] The bandgap reference circuit and image sensor provided in this embodiment include a voltage multiplication module and a voltage difference module. The voltage multiplication module is used to generate a first voltage inversely proportional to the absolute temperature and multiply and adjust the first voltage to obtain a second voltage. The voltage difference module is used to generate a third voltage directly proportional to the absolute temperature and sum the second and third voltages to obtain a temperature-independent reference voltage. The voltage multiplication module multiplies the first voltage inversely proportional to the absolute temperature to obtain the second voltage, and the voltage difference module sums the second voltage inversely proportional to the absolute temperature and the third voltage directly proportional to the absolute temperature to obtain the reference voltage. Thus, by adjusting the functions of the circuit modules, the circuit area and power consumption are effectively reduced, the accuracy of the reference voltage is improved, and the problems of large area and high power consumption of existing bandgap reference circuits are solved.

[0085] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A bandgap reference circuit, characterized in that: The invention comprises a voltage doubling module and a voltage difference module; the voltage doubling module is used to generate a first voltage inversely proportional to the absolute temperature, and to multiply and adjust the first voltage to obtain a second voltage; the voltage difference module is used to generate a third voltage proportional to the absolute temperature, and to sum the second and third voltages to obtain a reference voltage that is independent of temperature; The voltage doubling module includes a negative temperature coefficient voltage generating unit and a voltage dividing unit; the negative temperature coefficient voltage generating unit is used to generate the first voltage which is inversely proportional to the absolute temperature; the voltage dividing unit is used to multiply and adjust the first voltage to obtain the second voltage; The negative temperature coefficient voltage generating unit includes a first transistor, and the voltage dividing unit includes a first resistor and a second resistor; the gate and drain of the first transistor are connected and connected to a current source, and the source of the first transistor is grounded; the first end of the first resistor is connected to the current source; the second end of the first resistor is connected to the first end of the second resistor and to the drain of the first transistor; the second end of the second resistor is grounded; wherein, the drain of the first transistor generates the first voltage, and the first end of the first resistor generates the second voltage; the first transistor is a single MOS tube operating in the subthreshold region; the resistance of the first resistor is smaller than the resistance of the second resistor.

2. The bandgap reference circuit according to claim 1, wherein: The voltage doubling module also includes a first op amp; a first input end of the first op amp is connected to the drain of the first transistor, a second input end of the first op amp is connected to the output end of the first op amp, and the output end of the first op amp is connected to the second end of the first resistor.

3. The bandgap reference circuit according to claim 1, wherein: The voltage difference module includes a voltage stabilization and noise filtering unit and a positive temperature coefficient voltage generation unit; the voltage stabilization and noise filtering unit is used to perform voltage stabilization and noise filtering on the second voltage, and transmit the second voltage after voltage stabilization and noise filtering to the positive temperature coefficient voltage generation unit; the positive temperature coefficient voltage generation unit is used to generate the third voltage that is proportional to the absolute temperature, and sum the second voltage and the third voltage to obtain a reference voltage that is independent of temperature.

4. The bandgap reference circuit according to claim 3, wherein: The voltage stabilization and noise filtering unit includes a second operational amplifier, and the positive temperature coefficient voltage generating unit includes a second transistor; The first input terminal of the second op amp is connected to the second voltage, the second input terminal of the second op amp is connected to the output terminal of the second op amp, and the output terminal of the second op amp is connected to the gate of the second transistor; the drain of the second transistor is connected to the gate and connected to the second voltage, and the source of the second transistor is connected to the current source and outputs a reference voltage.

5. The bandgap reference circuit according to claim 4, wherein: The second transistors are multiple MOS transistors connected in parallel and operating in a subthreshold region.

6. The bandgap reference circuit according to claim 4, wherein: The voltage difference module also includes a current mirror; the current mirror includes a third transistor and a fourth transistor; the drain of the third transistor is connected to the gate and is connected to the current source, and the gate of the third transistor is connected to the gate of the fourth transistor; the drain of the fourth transistor is connected to the source of the second transistor; the source of the third transistor and the source of the fourth transistor are both grounded.

7. An image sensor, characterized in that: The method comprises the bandgap reference circuit according to any one of claims 1 to 6.

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