A high-precision and low-temperature drift reference voltage circuit

Abstract

The present invention relates to the field of analog integrated circuit technology, and in particular to a high-precision, low-temperature drift reference voltage circuit, a start-up bias module; a bandgap reference module, which is designed based on a Brokaw bandgap reference source model, and combined with a P-type base resistor to achieve second-order temperature compensation of a bandgap reference voltage; the bandgap reference module is composed of a transistor N14, a transistor N15, a metal film resistor R16, a metal film resistor R17, a metal film resistor R18, a metal film resistor R19, a metal film resistor R22, and a P-type base resistor R23; an operational amplifier OPA, which forms a closed loop with the bandgap reference module, and has sufficient current amplification capability to ensure the quiescent current required by the output end, and provide a high-precision output reference voltage. The present invention can provide a second-order voltage component with a positive temperature coefficient for the bandgap reference module, which is used to reduce the temperature coefficient of the bandgap reference voltage, and finally achieve the low temperature drift characteristic of the output reference voltage.

Description

Technical Field

[0001] The invention relates to the technical field of analog integrated circuits, and in particular to a high-precision and low-temperature drift reference voltage circuit. Background Art

[0002] As an important component of high-performance chips, the reference voltage circuit can provide one or more high-precision, low-temperature drift reference voltages for a single circuit or multiple circuit modules. It is widely used in a series of high-performance digital and analog integrated circuits such as ADC, DAC and LDO. The reference voltage output by the reference voltage circuit will directly affect the output performance of the entire system. The accuracy, temperature drift coefficient and anti-interference ability of the reference voltage are particularly important to the entire application system. Therefore, it is of great research significance to study the reference voltage circuit with high precision and low temperature drift. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-precision, low-temperature drift reference voltage circuit in view of the shortage of high-performance reference voltage circuits.

[0004] In order to solve the above technical problems, the present invention provides a high-precision and low-temperature drift reference voltage circuit, comprising:

[0005] A startup bias module is used to complete the startup of the entire circuit after the circuit is powered on, and to limit the startup current of the circuit to a safe current range, while providing the required bias current inside the circuit; the startup bias module is composed of transistor N1, transistor N2, transistor N3, transistor N4, transistor P1, resistor R1, resistor R2 and resistor R8;

[0006] The bandgap reference module is designed based on the Brokaw bandgap reference source model and combines the P-type base resistor to realize the second-order temperature compensation of the bandgap reference voltage; the bandgap reference module is composed of a transistor N14, a transistor N15, a metal film resistor R16, a metal film resistor R17, a metal film resistor R18, a metal film resistor R19, a metal film resistor R22 and a P-type base resistor R23;

[0007] The operational amplifier OPA forms a closed loop with the bandgap reference module and has sufficient current amplification capability to ensure the quiescent current required by the output terminal and provide a high-precision output reference voltage.

[0008] Preferably, it also includes reference output voltage sampling resistors R20 and R21, and the specific connection relationship between the bandgap reference module and the operational amplifier OPA is:

[0009] One end of the resistor R16 is connected to the resistor R17 and the output port VOUT of the operational amplifier OPA, and the other end is connected to the collector of the transistor N14 and the reverse input terminal of the operational amplifier OPA; the other end of the resistor R17 is connected to the collector of the transistor N15 and the forward input terminal of the operational amplifier OPA; the emitter of the transistor N14 is connected to one end of the resistor R18, and the other end of the resistor R18 is connected to the resistor R19 and the emitter of the transistor N15; the other end of the resistor R19 is connected to the resistor R22 and the resistor R23, and the other ends of the resistor R22 and the resistor R23 are connected to GND; the bases of the transistor N14 and the transistor N15 are connected, and are connected to the resistor R20 and the resistor R21, the other end of the resistor R20 is connected to the output port VOUT of the operational amplifier OPA, and the other end of the resistor R21 is connected to GND.

[0010] Preferably, the operational amplifier OPA includes: transistor N5, transistor N6, transistor N7, transistor N8, transistor N9, transistor N10, transistor N11, transistor N12, transistor N13, transistor P2, transistor P3, transistor P4, transistor P5, transistor P6, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15 and capacitor C1.

[0011] Preferably, the operational amplifier OPA has an input pole circuit with a three-stage amplification structure, including: a first-stage differential amplification structure formed by transistor N5 and transistor N6, a second-stage differential amplification structure formed by transistor P4 and transistor P5, and a third-stage differential amplification structure formed by transistor N7 and transistor N8, and the first-stage differential amplification structure and the third-stage differential amplification structure are common-collector amplification structures, and the second-stage differential amplification structure is a common-emitter amplification structure.

[0012] Preferably, the operational amplifier OPA, wherein the intermediate stage circuit is a common emitter-common collector amplifier structure, the common emitter amplifier structure formed by the transistor N7 tube improves the amplifier capability of voltage and current; the common collector amplifier structure formed by the transistor P6 tube further improves the current amplification capability.

[0013] Preferably, the output stage circuit of the operational amplifier OPA is a voltage follower structure, and an NPN tube with a larger emitter area, namely, a triode N13 tube, is selected for design, which improves the current amplification capability while ensuring the ability of large current output. The power output of the overall circuit is guaranteed by the triode N13 tube.

[0014] Preferably, the operational amplifier OPA has an output end whose emitter port of transistor N13 serves as a power output port.

[0015] Preferably, the specific connection relationship between the startup bias module and the operational amplifier OPA is:

[0016] One end of the resistor R1 is connected to the power supply voltage VCC, and the other end is connected to the base, collector and base of transistor N1; the emitter of transistor N1 is connected to the collector of transistor N3 and the base of transistor N4, and the emitter of transistor N3 is connected to GND, the emitter of transistor N4 is grounded through resistor R8, the base of transistor N3, the collector of transistor N4 and the emitter of transistor N2 are connected; the collector of transistor N2 is respectively connected to the base, collector and base of transistor P1 and transistor P2, the emitter of transistor P1 is connected to the power supply voltage VCC through resistor R2, and the emitter of transistor P2 is connected to the power supply voltage VCC through resistor R3. The transistor P3 is connected to the power supply voltage VCC, the emitter of the transistor P3 is connected to the base, collector and one end of the resistor R4 of the transistor N12, the other end of the resistor R4 is connected to the power supply voltage VCC, the emitter of the transistor N12 is connected to the resistor R5 and the collector of the transistor N13, the base of the transistor N13 is respectively connected to one end of the resistor R6, the collector of the transistor P3 and the emitter of the transistor P6, the emitter of the transistor N13 is connected to the other end of the resistor R6 and the output port VOUT; the base of the transistor N5 is connected to the positive input terminal VIN+ of the operational amplifier OPA, and the emitter is connected to the base of the transistor P4 and one end of the resistor R9; the The base is connected to the reverse input terminal VIN- of the operational amplifier OPA, and the emitter is connected to the base of the transistor P5 and one end of the resistor R10; the other ends of the resistors R9 and R10 are connected to GND, and the collectors of the transistors N5, N6, N7 and N8 and one end of the resistor R7 are connected to the output port VOUT; the emitters of the transistors P4 and P5 are connected to the other end of the resistor R7, the collector of the transistor P4 is connected to the collector of the transistor N9 and the base of the transistor N7, the collector of the transistor P5 is connected to the collector of the transistor N10, the base of the transistor N8 and one end of the capacitor C1; the transistor N9 The emitter of transistor N10 is connected to GND through resistor R11, the emitter of transistor N10 is connected to GND through resistor R12, the base of transistor N9 and transistor N10 is connected to the emitter of transistor N7 and one end of resistor R12, and the other end of resistor R12 is connected to GND; the emitter of transistor N8 is connected to the base of transistor N11 and one end of resistor R14, the other end of resistor R14 is connected to GND, the collector of transistor N11 is connected to the other end of capacitor C1 and the base of transistor P6 and the collector of transistor P2, the emitter of transistor N11 is connected to GND through resistor R15, and the collector of transistor P6 is connected to GND.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a reference voltage circuit that uses a second-order curvature compensation technology to achieve high precision and low temperature drift. The design is completed based on the Brokaw bandgap reference source model. The overall circuit includes a startup module, a bandgap reference module and an amplifier module, and metal film resistors and P-type base resistors are used. Among them, the metal film resistor has a very good temperature characteristic, which can ensure the temperature stability of the output reference voltage. At the same time, the metal film resistor can also adjust the size of the resistance through subsequent laser trimming to achieve a high-precision output reference voltage; the P-type base resistor has a second-order positive temperature coefficient characteristic, which can provide a second-order voltage component with a positive temperature coefficient for the bandgap reference module, which is used to reduce the temperature coefficient of the bandgap reference voltage, and finally achieve the low temperature drift characteristic of the output reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a circuit diagram of the bandgap reference module and the operational amplifier OPA of the present invention.

[0020] Figure 2 It is a circuit diagram of the startup bias module and the operational amplifier OPA of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0022] The present invention is a high-precision, low-temperature drift reference voltage circuit that uses second-order curvature compensation technology. The design is based on the Brokaw bandgap reference source model. The overall circuit includes a startup module, a bandgap reference module, and an operational amplifier OPA. At the same time, a metal film resistor (i.e. Figure 1 All resistors except R23 are metal film resistors) and P-type base resistor R23. Among them, the metal film resistor has a very good temperature characteristic, which can ensure the temperature stability of the output reference voltage. At the same time, the metal film resistor R19 and the metal film resistor R20 can adjust the resistance through the subsequent laser trimming to achieve a high-precision output reference voltage; the P-type base resistor R23 has a second-order positive temperature coefficient characteristic, which can provide a second-order voltage component with a positive temperature coefficient for the bandgap reference module to reduce the temperature coefficient of the bandgap reference voltage, and finally achieve a low temperature drift characteristic of the output reference voltage.

[0023] The startup bias module consists of Figure 2The resistor R1, transistor N2 and transistor N3 form the startup branch of the overall circuit. The size of the resistor R1 directly determines the size of the startup current. At the same time, the cross-coupled current source is combined with the proportional current source to provide the required bias current for the operational amplifier OPA.

[0024] The bandgap reference module is designed based on the Brokaw bandgap reference source model. Figure 1 In the circuit, the transistor N14 with a certain proportional emitter area is connected to the base of the transistor N15, and its collector is connected to the output port VOUT of the overall circuit through resistors R16 and R17 respectively. The emitter end of the transistor N14 with a larger emitter area is connected to a small resistor R18. Due to the principle that the larger the emitter area of ​​the transistor, the lower the tube voltage drop, a reference current is generated after the series resistor R18, and the second-order temperature compensation of the bandgap reference voltage is completed in combination with the metal film resistors R19, R22 and the P-type base resistor R23. Combined with the laser trimming of the metal film resistor R19, a bandgap reference voltage with extremely low temperature drift can be output in the later stage.

[0025] The operational amplifier OPA has a three-stage input amplifier structure. Figure 2 , including the first-stage differential amplification structure (NPN differential pair composed of transistor N5 and transistor N6), the second-stage differential amplification structure (PNP differential pair composed of transistor P4 and transistor P5), and the third-stage differential amplification structure (NPN differential pair composed of transistor N7 and transistor N8), which greatly improves the amplification capability of the input stage circuit and reduces the input offset of the amplification. The intermediate stage circuit consists of a two-stage amplification structure composed of transistor N7 and transistor P6. The common emitter amplification structure composed of transistor N7 improves the voltage and current amplifier capabilities at the same time. The common collector amplification structure composed of transistor P6 further improves the current amplification capability. The output stage is a voltage follower structure, and the NPN tube with a larger emitter area, namely the transistor N13, is selected for design. While improving the current amplification capability, it also ensures the ability to output large current. The transistor N13 ensures the power output of the overall circuit. The sampling resistor R5 and the protection transistor N12 are designed at the output end of the op amp. When the output current reaches a certain level, the protection transistor is turned on to achieve overall over-current protection.

[0026] like Figure 1As shown, one end of the resistor R16 is connected to the resistor R17 and the output port VOUT of the operational amplifier OPA, and the other end is connected to the collector of the transistor N14 and the reverse input terminal of the operational amplifier OPA; the other end of the resistor R17 is connected to the collector of the transistor N15 and the positive input terminal of the operational amplifier OPA; the emitter of the transistor N14 is connected to one end of the resistor R18, and the other end of the resistor R18 is connected to the resistor R19 and the emitter of the transistor N15; the other end of the resistor R19 is connected to the resistor R22 and the resistor R23, and the other ends of the resistor R22 and the resistor R23 are connected to GND; the bases of the transistor N14 and the transistor N15 are connected, and are connected to the resistors R20 and R21, the other end of the resistor R20 is connected to the output port VOUT of the operational amplifier OPA, and the other end of the resistor R21 is connected to GND.

[0027] like Figure 1 As shown, transistors N14 and N15, operational amplifier OPA, resistors R18 and R19 together form the basic structure of the bandgap reference voltage. Since the emitter areas of N14 and N15 are designed to be 12:1, the turn-on voltage of N14 is lower than that of N15. Selecting a suitable resistor R18 can generate the required reference current. Resistors R19 and R22 are both metal film resistors, which have good temperature characteristics and complete the first-order compensation of the bandgap reference voltage in combination with the turn-on voltage of N15. Since the turn-on voltage of transistor N15 decreases with increasing temperature and contains high-order components, and metal film resistors have positive temperature coefficients, the voltage generated on resistors R19 and R22 cannot offset the high-order components generated by the turn-on voltage of transistor N15 with temperature changes. Therefore, a P-type base resistor R23 is introduced. The P-type base resistor R23 has positive temperature characteristics and contains high-order components with temperature changes. A resistor R23 of a reasonable size is selected, and the bandgap reference module provides a PTAT. 2 The voltage component of the bandgap reference is used to complete the second-order temperature compensation of the bandgap reference voltage, greatly reducing the temperature drift coefficient of the bandgap reference voltage. Among them, the resistance values ​​of resistors R16 and R17 are equal, which can reduce the overall offset of the circuit and improve the power supply voltage rejection ratio of the circuit. Resistors R19 and R20 are both designed as adjustable resistors, and laser trimming is performed according to the actual tape-out results of the production process. Laser trimming of resistor R19 achieves a low temperature drift coefficient of the reference voltage, and laser trimming of resistor R20 achieves high precision of the final output reference voltage.

[0028] like Figure 2As shown, one end of the resistor R1 is connected to the power supply voltage VCC, and the other end is connected to the base, collector and base of transistor N1; the emitter of transistor N1 is connected to the collector of transistor N3 and the base of transistor N4, and the emitter of transistor N3 is connected to GND, the emitter of transistor N4 is grounded through resistor R8, the base of transistor N3, the collector of transistor N4 and the emitter of transistor N2 are connected; the collector of transistor N2 is respectively connected to the base, collector and base of transistor P1 and transistor P2, the emitter of transistor P1 is connected to the power supply voltage VCC through resistor R2, and the emitter of transistor P2 is connected to ground through resistor R8. R3 is connected to the power supply voltage VCC, the emitter of transistor P3 is connected to the base, collector and one end of resistor R4 of transistor N12, the other end of resistor R4 is connected to the power supply voltage VCC, the emitter of transistor N12 is connected to resistor R5 and the collector of transistor N13, the base of transistor N13 is respectively connected to one end of resistor R6, the collector of transistor P3 and the emitter of transistor P6, the emitter of transistor N13 is connected to the other end of resistor R6 and the output port VOUT; the base of transistor N5 is connected to the positive input terminal VIN+ of the operational amplifier OPA, and the emitter is connected to the base of transistor P4 and one end of resistor R9; transistor N6 The base of the transistor is connected to the reverse input terminal VIN- of the operational amplifier OPA, and the emitter is connected to the base of the transistor P5 and one end of the resistor R10; the other ends of the resistors R9 and R10 are connected to GND, and the collectors of the transistors N5, N6, N7 and N8 and one end of the resistor R7 are connected to the output port VOUT; the emitters of the transistors P4 and P5 are connected to the other end of the resistor R7, the collector of the transistor P4 is connected to the collector of the transistor N9 and the base of the transistor N7, the collector of the transistor P5 is connected to the collector of the transistor N10, the base of the transistor N8 and one end of the capacitor C1; the transistor N9 The emitter of the transistor is connected to GND through resistor R11, the emitter of the transistor N10 is connected to GND through resistor R12, the base of the transistor N9 and the transistor N10 is connected to the emitter of the transistor N7 and one end of the resistor R12, and the other end of the resistor R12 is connected to GND; the emitter of the transistor N8 is connected to the base of the transistor N11 and one end of the resistor R14, the other end of the resistor R14 is connected to GND, the collector of the transistor N11 is connected to the other end of the capacitor C1 and the base of the transistor P6 and the collector of the transistor P2, the emitter of the transistor N11 is connected to GND through resistor R15, and the collector of the transistor P6 is connected to GND.

[0029] like Figure 2As shown, resistors R1, R8, N2 and N3 form a startup branch, which is initially turned on when the circuit is powered on, and then the entire circuit is turned on. Resistor R1 is a large-value resistor that can limit the startup current to ensure safe startup of the circuit. The bias current of the overall circuit is determined by resistor R8, and is converted into the bias current required for each path through a proportional current source composed of P1, P2, P3, and resistors R2, R3, and R4. Ports VIN+ and VIN- represent the positive and negative input ports of the amplifier, respectively, and are Figure 1 The positive and negative ports of the amplifier OPA in the middle correspond to each other. Port VOUT is the output port of the operational amplifier, which is Figure 1 The output ports of the amplifier are connected. The N5 tube and the N6 tube form the first differential amplifier structure of the amplifier, the P4 tube and the P5 tube form the second differential amplifier structure of the amplifier, and the N7 tube and the N8 tube form the third differential amplifier structure of the amplifier. The three differential amplifier structures are all common collector amplifier structures, which do not have voltage amplification capabilities, but have strong current amplification capabilities, which can effectively reduce the offset voltage of the amplifier and improve the current gain of the amplifier. At the same time, the addition of compensation capacitor C1 effectively improves the stability of the circuit. The N11 tube of common emitter amplification and the P6 tube of common collector amplification further improve the current amplification capability of the overall circuit. The N13 tube is a power output tube. It is designed as a multi-tube parallel structure, which can achieve a strong current driving capability, which is convenient for further amplification of the current signal output by the previous stage. Resistor R5 and N12 tube form an overcurrent protection structure. When the output current exceeds the design target, the voltage dropped on resistor R5 turns on N12, causing the current on R4 to flow directly into the collector of N12 tube, directly turning off the bias circuit composed of P3 tube, and turning off the intermediate stage P6 tube of the amplifier, thereby achieving the purpose of protecting the amplifier circuit.

[0030] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art 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 high-precision, low-temperature drift reference voltage circuit, characterized in that: include: A startup bias module is used to complete the startup of the entire circuit after the circuit is powered on, and to limit the startup current of the circuit to a safe current range, while providing the required bias current inside the circuit; the startup bias module is composed of transistor N1, transistor N2, transistor N3, transistor N4, transistor P1, resistor R1, resistor R2 and resistor R8; The bandgap reference module is designed based on the Brokaw bandgap reference source model and combines the P-type base resistor to realize the second-order temperature compensation of the bandgap reference voltage; the bandgap reference module is composed of a transistor N14, a transistor N15, a metal film resistor R16, a metal film resistor R17, a metal film resistor R18, a metal film resistor R19, a metal film resistor R22 and a P-type base resistor R23; The operational amplifier OPA forms a closed loop with the bandgap reference module and has sufficient current amplification capability to ensure the quiescent current required by the output terminal and provide a high-precision output reference voltage; The specific connection relationship between the startup bias module and the operational amplifier OPA is: One end of the resistor R1 is connected to the power supply voltage VCC, and the other end is connected to the base, collector and base of transistor N1; the emitter of transistor N1 is connected to the collector of transistor N3 and the base of transistor N4, and the emitter of transistor N3 is connected to GND, the emitter of transistor N4 is grounded through resistor R8, the base of transistor N3, the collector of transistor N4 and the emitter of transistor N2 are connected; the collector of transistor N2 is respectively connected to the base, collector and base of transistor P1 and transistor P2, the emitter of transistor P1 is connected to the power supply voltage VCC through resistor R2, and the emitter of transistor P2 is connected to the power supply voltage VCC through resistor R3. The transistor P3 is connected to the power supply voltage VCC, the emitter of the transistor P3 is connected to the base, collector and one end of the resistor R4 of the transistor N12, the other end of the resistor R4 is connected to the power supply voltage VCC, the emitter of the transistor N12 is connected to the resistor R5 and the collector of the transistor N13, the base of the transistor N13 is respectively connected to one end of the resistor R6, the collector of the transistor P3 and the emitter of the transistor P6, the emitter of the transistor N13 is connected to the other end of the resistor R6 and the output port VOUT; the base of the transistor N5 is connected to the positive input terminal VIN+ of the operational amplifier OPA, and the emitter is connected to the base of the transistor P4 and one end of the resistor R9; the The base is connected to the reverse input terminal VIN- of the operational amplifier OPA, and the emitter is connected to the base of the transistor P5 and one end of the resistor R10; the other ends of the resistors R9 and R10 are connected to GND, and the collectors of the transistors N5, N6, N7 and N8 and one end of the resistor R7 are connected to the output port VOUT; the emitters of the transistors P4 and P5 are connected to the other end of the resistor R7, the collector of the transistor P4 is connected to the collector of the transistor N9 and the base of the transistor N7, the collector of the transistor P5 is connected to the collector of the transistor N10, the base of the transistor N8 and one end of the capacitor C1; the transistor N9 The emitter of transistor N10 is connected to GND through resistor R11, the emitter of transistor N10 is connected to GND through resistor R12, the base of transistor N9 and transistor N10 is connected to the emitter of transistor N7 and one end of resistor R13, and the other end of resistor R13 is connected to GND; the emitter of transistor N8 is connected to the base of transistor N11 and one end of resistor R14, the other end of resistor R14 is connected to GND, the collector of transistor N11 is connected to the other end of capacitor C1 and the base of transistor P6 and the collector of transistor P2, the emitter of transistor N11 is connected to GND through resistor R15, and the collector of transistor P6 is connected to GND.

2. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 1, characterized in that: It also includes reference output voltage sampling resistors R20 and R21, and the specific connection relationship between the bandgap reference module and the operational amplifier OPA is: One end of the resistor R16 is connected to the resistor R17 and the output port VOUT of the operational amplifier OPA, and the other end is connected to the collector of the transistor N14 and the reverse input terminal of the operational amplifier OPA; the other end of the resistor R17 is connected to the collector of the transistor N15 and the forward input terminal of the operational amplifier OPA; the emitter of the transistor N14 is connected to one end of the resistor R18, and the other end of the resistor R18 is connected to the resistor R19 and the emitter of the transistor N15; the other end of the resistor R19 is connected to the resistor R22 and the resistor R23, and the other ends of the resistor R22 and the resistor R23 are connected to GND; the bases of the transistor N14 and the transistor N15 are connected, and are connected to the resistor R20 and the resistor R21, the other end of the resistor R20 is connected to the output port VOUT of the operational amplifier OPA, and the other end of the resistor R21 is connected to GND.

3. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 1, characterized in that: The operational amplifier OPA includes: transistor N5, transistor N6, transistor N7, transistor N8, transistor N9, transistor N10, transistor N11, transistor N12, transistor N13, transistor P2, transistor P3, transistor P4, transistor P5, transistor P6, resistor R3, resistor R4, resistor R5, resistor R6, resistor R7, resistor R9, resistor R10, resistor R11, resistor R12, resistor R13, resistor R14, resistor R15 and capacitor C1.

4. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 3, characterized in that: The operational amplifier OPA has an input circuit of a three-stage amplification structure, including: a first-stage differential amplification structure composed of a transistor N5 and a transistor N6, a second-stage differential amplification structure composed of a transistor P4 and a transistor P5, and a third-stage differential amplification structure composed of a transistor N7 and a transistor N8, and the first-stage differential amplification structure and the third-stage differential amplification structure are common-collector amplification structures, and the second-stage differential amplification structure is a common-emitter amplification structure.

5. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 3, characterized in that: The operational amplifier OPA, wherein the intermediate circuit is a common emitter-common collector amplification structure, the common emitter amplification structure formed by the transistor N7 tube improves the amplification capability of voltage and current; the common collector amplification structure formed by the transistor P6 tube further improves the current amplification capability.

6. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 3, characterized in that: The operational amplifier OPA has an output stage circuit of a voltage follower structure, and an NPN tube with a larger emitter area, namely, a triode N13 tube, is selected for design, which improves the current amplification capability while ensuring the ability of large current output. The triode N13 tube ensures the power output of the overall circuit.

7. A high-precision, low-temperature drift reference voltage circuit as claimed in claim 3, characterized in that: The operational amplifier OPA has an output end whose output terminal is the emitter port of the transistor N13 as a power output port.

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