A low temperature drift reference circuit

Abstract

The present invention discloses a low-temperature drift reference circuit, belonging to the field of electronic circuit technology. The circuit includes a startup unit, a reference core unit, and a base current sink unit. The startup unit is connected to the reference core unit and the base current sink unit, and the reference core unit is connected to the base current sink unit. The low-temperature drift reference circuit of the present invention utilizes a T-type resistor network, relies on a positive temperature coefficient voltage expansion term, compensates for a negative temperature coefficient voltage, and can obtain a low-temperature drift reference voltage. The reference voltage can be adjusted by changing the resistor type and resistance value of the resistor network and the proportional relationship of the current mirror.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a low-temperature drift reference circuit. Background Art

[0002] The reference voltage source is a key module in the design of modern analog mixed circuits. With the continuous changes in application scenarios, there is a demand for higher precision of the reference voltage source in analog chips, that is, a lower temperature coefficient is required in a wider temperature range.

[0003] In existing CMOS bandgap reference circuits, the maximum operating voltage of CMOS devices is only 5.5V, and the reference output voltage is generally around 1.20V. The temperature drift coefficient of this reference circuit is mostly concentrated in 50ppm. In addition, this reference circuit also uses an NPN structure, and the base current directly affects its temperature drift coefficient.

[0004] Existing bandgap reference circuits using PMOS outputs further increase the loop gain, but sacrifice the output load capability. In addition, their temperature drift coefficients are mostly concentrated at 50ppm.

[0005] Therefore, how to achieve low temperature drift of the reference circuit has become an urgent problem to be solved. Summary of the Invention

[0006] The present invention aims to provide a low-temperature drift reference circuit.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] A low-temperature drift reference circuit comprises a startup unit, a reference core unit, and a base current absorption unit, wherein the startup unit is connected to the reference core unit and the base current absorption unit, and the reference core unit is connected to the base current absorption unit;

[0009] The reference core unit includes a plurality of transistors, a plurality of triodes, a plurality of resistors, a first resistor network, and a second resistor network. The second end of the seventh transistor is connected to the first voltage, the first end of the seventh transistor is connected to the third end of the seventh transistor and the first end of the fifth transistor, the second end of the fifth transistor is connected to the first end of the third triode, the second end of the third triode is connected to the first end of the first resistor network, the third end of the first resistor network is grounded via a third resistor, the second end of the eighth transistor is connected to the first voltage, the third end of the eighth transistor is connected to the third end of the seventh transistor and the third end of the first transistor, the first end of the eighth transistor is connected to the first end of the sixth transistor, the third end of the sixth transistor is connected to the third end of the fifth transistor and the third end of the third transistor, and the third end of the sixth transistor is connected to the first end of the fourth triode. The second end of the fourth transistor is connected to the second end of the first resistor network through the second resistor, the third ends of the fifth transistor and the sixth transistor are also connected to the first end of the eighteenth transistor, the second end of the eighteenth transistor is grounded, the first end of the second resistor network is connected to the third end of the third transistor and the second end of the second transistor, the second end of the second resistor network is connected to the third end of the fourth transistor, the second end of the ninth transistor is connected to the first voltage, the first end of the ninth transistor is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is grounded, the third end of the ninth transistor is connected to the first end of the eighth transistor, the first capacitor is connected between the first end and the third end of the ninth transistor, the fourth end of the second resistor network is connected to the first end of the sixteenth transistor, and the second end of the sixteenth transistor is grounded.

[0010] In a specific embodiment, the first resistor network includes a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, a thirty-sixth resistor, and a thirty-seventh resistor. The first end of the thirty-first resistor is the first end of the first resistor network, the second end of the thirty-first resistor is connected to the first end of the thirty-second resistor, and the second end of the thirty-second resistor is connected to the first end of the second resistor network. The first end of the thirty-third resistor is connected to the first end of the thirty-first resistor, and the second end of the thirty-third resistor is connected to the second end of the thirty-second resistor. The first end of the thirty-fourth resistor is connected to the first end of the second resistor network, and the second end of the thirty-fourth resistor is connected to the first end of the thirty-fifth resistor. The second end of the thirty-fifth resistor is the second end of the first resistor network. The first end of the thirty-sixth resistor is connected to the first end of the thirty-fourth resistor, and the second end of the thirty-sixth resistor is connected to the second end of the thirty-fifth resistor. The first end of the thirty-seventh resistor is connected to the first end of the second resistor network, and the second end of the thirty-seventh resistor is the third end of the first resistor network.

[0011] In a specific embodiment, the second resistor network includes a forty-first resistor, a forty-second resistor, a forty-third resistor, and a forty-fourth resistor. The first end of the forty-second resistor is the first end of the second resistor network, the second end of the forty-second resistor is connected to the first ends of the forty-first resistor, the forty-third resistor, and the forty-fourth resistor, the second end of the forty-fourth resistor is the second end of the second resistor network, the second end of the forty-third resistor is the third end of the second resistor network, and the second end of the forty-first resistor is the fourth end of the second resistor network.

[0012] In a specific embodiment, the startup unit includes multiple resistors, multiple transistors, and multiple triodes. The first voltage is connected to the first end of the second transistor through the zeroth resistor, the second end of the second transistor is connected to the first end of the first transistor, the second end of the first transistor is connected to the first voltage, the first end of the second transistor is connected to the first end of the third transistor, the second end of the third transistor is connected to the first end and the third end of the zeroth triode, the third end of the third transistor is connected to the first end of the first transistor, the second end of the zeroth triode is connected to the first end and the third end of the first triode, the second end of the first triode is grounded through the first resistor, the third end of the zeroth triode is connected to the third end of the second triode, the first end of the second triode is connected to the first voltage, the second end of the second triode is connected to the first end of the seventeenth transistor, the second end of the seventeenth transistor is grounded, the third end of the zeroth triode is connected to the first end of the fourth transistor, and the second end of the fourth transistor is grounded.

[0013] In a specific embodiment, the startup unit includes multiple resistors, multiple transistors, and multiple triodes. The first voltage is connected to the first end and the third end of the twenty-first transistor through the twentieth resistor. The second end of the twenty-first transistor is connected to the first end and the third end of the twenty-third transistor. The second end of the twenty-third transistor is connected to the first end and the third end of the twenty-first triode. The second end of the twenty-first triode is grounded. The first end of the twenty-second transistor is connected to the first voltage. The third end of the twenty-second transistor is connected to the third end of the twenty-first transistor. The second end of the twenty-third transistor is connected to the first voltage. The first end of the twenty-third transistor is connected to the second end of the twenty-fifth transistor. The first end of the twenty-fifth transistor is connected to the first end and the third end of the twenty-seventh transistor. The third end of the twenty-seventh transistor is connected to the second end of the twenty-second transistor. The second end of the twenty-seventh transistor is connected to the first end and the third end of the twenty-second triode. The second end of the twenty-second triode is grounded. The second end of the twenty-fourth transistor is connected to the first voltage. The third end of the twenty-fourth transistor is connected to the third end of the twenty-third transistor and the first end of the twenty-sixth transistor. The first end of the twenty-fourth transistor is connected to the second end of the twenty-sixth transistor. The third end of the twenty-sixth transistor is connected to the third end of the twenty-fifth transistor. The first end of the twenty-sixth transistor is connected to the third end of the twenty-sixth transistor and the first end of the twenty-eighth transistor through the twenty-first resistor, the third end of the twenty-eighth transistor is connected to the third end of the twenty-seventh transistor, the second end of the twenty-eighth transistor is connected to the first end of the twenty-third transistor, the third end of the twenty-third transistor is connected to the third end of the twenty-second transistor, the second end of the twenty-third transistor is grounded through the twenty-second resistor, the second end of the zeroth transistor is connected to the first voltage, the third end of the zeroth transistor is connected to the third end of the twenty-fourth transistor, the first end of the zeroth transistor is connected to the first end of the second transistor, and the second transistor The first end of the transistor is connected to the first end of the third transistor, the second end of the third transistor is connected to the first end and the third end of the zeroth transistor, the third end of the third transistor is connected to the second end of the second transistor, the second end of the zeroth transistor is connected to the first end and the third end of the first transistor, the second end of the first transistor is grounded through the first resistor, the third end of the zeroth transistor is connected to the third end of the second transistor, the first end of the second transistor is connected to the first voltage, the second end of the second transistor is connected to the first end of the seventeenth transistor, the second end of the seventeenth transistor is grounded, the third end of the zeroth transistor is connected to the first end of the fourth transistor, and the second end of the fourth transistor is grounded.

[0014] In a specific embodiment, the base current absorption unit includes multiple resistors, multiple transistors, and multiple triodes. The second end of the tenth transistor is connected to the first voltage, the first end of the tenth transistor is connected to the first end and the third end of the fourteenth transistor, the second end of the fourteenth transistor is grounded, the third end of the fourteenth transistor is connected to the third end of the fifteenth transistor, the first end of the fifteenth transistor is connected to the third end of the second resistor network, the second end of the fifteenth transistor is grounded, the second end of the eleventh transistor is connected to the first voltage, the first end of the eleventh transistor is connected to the fourth end of the second resistor network, the second end of the twelfth transistor is connected to the first voltage, and the third end of the twelfth transistor is connected to the seventh transistor. The third end of the eighth transistor and the first end of the twelfth transistor are connected to the first end of the fifth transistor, the second end of the fifth transistor is grounded, the second end of the thirteenth transistor is connected to the first voltage, the third end of the thirteenth transistor is connected to the second end of the thirteenth transistor and the third end of the tenth transistor, the second end of the thirteenth transistor is connected to the first end of the seventh transistor, the third end of the seventh transistor is connected to the first end of the twelfth transistor, the second end of the seventh transistor is connected to the third end of the fifth transistor, the second end of the sixth resistor is connected to the first voltage, the second end of the sixth resistor is connected to the first end of the sixth transistor, the third end of the sixth transistor is connected to the third end of the fifth transistor, and the second end of the sixth transistor is grounded.

[0015] In one embodiment, the reference voltage V BG The expression is

[0016]

[0017] Among them, V BE is the base-emitter voltage of the transistor, ΔV BE is the change of the base-emitter voltage of the transistor with temperature, R3 is the resistance of the third resistor, R2 is the resistance of the second resistor, R eq is the equivalent resistance, β is the current amplification factor of the transistor, M represents the direct compensation amount introduced by the base current, N represents the compensation amount of the reference voltage, R42 is the resistance value of the forty-second resistor, and R41 is the resistance value of the forty-first resistor.

[0018] In a specific embodiment, the thirty-second resistor, the thirty-third resistor, the thirty-fifth resistor, the thirty-sixth resistor, and the thirty-seventh resistor are positive temperature coefficient resistors; and the thirty-first resistor and the thirty-fourth resistor are negative temperature coefficient resistors.

[0019] In a specific embodiment, the thirty-seventh resistor is a controllable resistor.

[0020] In one embodiment, the resistance of the thirty-seventh resistor is equal to that of the third resistor.

[0021] Beneficial effects: The present invention provides a low-temperature drift reference circuit based on a traditional Brokaw structure, combined with a base current compensation concept. This circuit utilizes a T-type resistor network, relies on a positive temperature coefficient voltage expansion term, and compensates for a negative temperature coefficient voltage, thereby obtaining a low-temperature drift reference voltage. By changing the resistor type and value of the resistor network and the proportional relationship of the current mirror, the magnitude of the reference voltage can be adjusted. Furthermore, the circuit of the present invention utilizes a conventional BCD process design to achieve a reference voltage with a low temperature drift coefficient within the range of -55°C to 150°C, meeting the reference voltage requirements of analog chips and improving the chip's voltage accuracy and temperature drift coefficient. Furthermore, the circuit can achieve a very small chip size (DIE SIZE), saving process costs. The circuit is suitable for both high- and low-voltage applications.

[0022] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a circuit diagram of a first specific embodiment of a low-temperature drift reference circuit of the present invention.

[0024] Figure 2 FIG. 4 is a circuit diagram of a specific embodiment of the first resistor network.

[0025] Figure 3 FIG. 4 is a circuit diagram of a specific embodiment of the second resistor network.

[0026] Figure 4 This is a circuit diagram of a second specific embodiment of a low-temperature drift reference circuit of the present invention.

[0027] Figure 5 This is the simulation waveform of the traditional Brokaw bandgap reference circuit.

[0028] Figure 6 This is the simulation waveform of the low-temperature drift reference circuit of this application.

[0029] Figure 7 This is a simulation waveform diagram of the low-temperature drift reference circuit of this application when the driving signal EN changes from low to high.

[0030] Figure 8 is the reference voltage V at different temperatures BG waveform. DETAILED DESCRIPTION

[0031] To make the purpose and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The present invention provides a low-temperature drift reference circuit, comprising a startup unit, a reference core unit, and a base current absorption unit. The startup unit is connected to the reference core unit and the base current absorption unit, and the reference core unit is connected to the base current absorption unit.

[0033] More specifically, the startup unit injects current into the reference core unit to generate a reference voltage; the base current sink unit injects current into the reference core unit to achieve current compensation, thereby obtaining a low-temperature drift reference voltage.

[0034] Figure 1 This is a circuit diagram of a first embodiment of a low-temperature drift reference circuit according to the present invention. In this embodiment, a startup unit 11 includes multiple resistors, multiple transistors, and multiple triodes. A voltage VDDA is connected to the first end of a transistor M2 through a resistor R0. The second end of the transistor M2 is connected to the first end of the transistor M1. The second end of the transistor M1 is connected to the voltage VDDA. The first end of the transistor M2 is connected to the first end of the transistor M3. The second end of the transistor M3 is connected to the first and third ends of the triode Q0. The third end of the transistor M3 is connected to the first end of the transistor M1. The second end of the triode Q0 is connected to the first and third ends of the triode Q1. The second end of the triode Q1 is connected to the ground GNDA through a resistor R1. The third end of the triode Q0 is connected to the third end of the triode Q2. The first end of the triode Q2 is connected to the voltage VDDA. The second end of the triode Q2 is connected to the first end of the transistor M17. The second end of the transistor M17 is connected to the ground GNDA. The third end of the triode Q0 is connected to the first end of the transistor M4. The second end of the transistor M4 is connected to the ground GNDA. The third terminal of the transistor M2 is connected to the driving signal EN, and the third terminals of the transistor M4 and the transistor M17 are connected to the driving signal ENB. The driving signal EN is opposite to the driving signal ENB.

[0035] Among them, the voltage VDDA plays a power supply role.

[0036] Please continue to refer to Figure 1In this specific embodiment, the reference core unit 12 includes multiple transistors, multiple transistors, multiple resistors, a first resistor network 121, and a second resistor network 122. The second end of the transistor M7 is connected to the voltage VDDA, the first end of the transistor M7 is connected to the third end of the transistor M7 and the first end of the transistor M5, the second end of the transistor M5 is connected to the first end of the transistor Q3, the second end of the transistor Q3 is connected to the first end V1 of the first resistor network 121, and the third end V3 of the first resistor network 121 is grounded to GNDA via the resistor R3. The second end of the transistor M8 is connected to the voltage VDDA, the third end of the transistor M8 is connected to the third end of the transistor M7 and the third end of the transistor M1, the first end of the transistor M8 is connected to the first end of the transistor M6, the third end of the transistor M6 is connected to the third end of the transistor M5 and the third end of the transistor M3, the third end of the transistor M6 is connected to the first end of the transistor Q4, and the second end of the transistor Q4 is connected to the ground GNDA via the resistor R3. Resistor R2 is connected to the second end V2 of the first resistor network 121. The third ends of transistors M5 and M6 are also connected to the first end of transistor M18. The second end of transistor M18 is grounded to GNDA. The first end V4 of the second resistor network 122 is connected to the third end of transistor Q3 and the second end of transistor Q2. The second end V5 of the second resistor network 122 is connected to the third end of transistor Q4. The second end of transistor M9 is connected to voltage VDDA. The first end of transistor M9 is connected to the first end of resistor R4. The second end of resistor R4 is connected to the first end of resistor R5. The second end of resistor R5 is grounded to GNDA. The third end of transistor M9 is connected to the first end of transistor M8. Capacitor C1 is connected between the first and third ends of transistor M9. The fourth end V7 of the second resistor network 122 is connected to the first end of transistor M16. The second end of transistor M16 is grounded to GNDA. The fourth end V7 of the second resistor network 122 outputs a reference voltage V BG The third terminals of the transistors M18 and M16 are connected to the driving signal ENB.

[0037] Please continue to refer to Figure 1In this specific embodiment, the base current sink unit 13 includes multiple resistors, multiple transistors, and multiple triodes. The second end of the transistor M10 is connected to the voltage VDDA, the first end of the transistor M10 is connected to the first end and the third end of the transistor M14, the second end of the transistor M14 is grounded to GNDA, the third end of the transistor M14 is connected to the third end of the transistor M15, the first end of the transistor M15 is connected to the third end V6 of the second resistor network 122, the second end of the transistor M15 is grounded to GNDA, the second end of the transistor M11 is connected to the voltage VDDA, the first end of the transistor M11 is connected to the fourth end V7 of the second resistor network 122, the second end of the transistor M12 is connected to the voltage VDDA, and the third end of the transistor M12 is connected to The first terminal of transistor M12 is connected to the first terminal of transistor Q5, the second terminal of transistor Q5 is connected to ground GNDA, the second terminal of transistor M13 is connected to voltage VDDA, the third terminal of transistor M13 is connected to the second terminal of transistor M13 and the third terminal of transistor M10, the second terminal of transistor M13 is connected to the first terminal of transistor Q7, the third terminal of transistor Q7 is connected to the first terminal of transistor M12, the second terminal of transistor Q7 is connected to the third terminal of transistor Q5, the second terminal of resistor R6 is connected to voltage VDDA, the second terminal of resistor R6 is connected to the first terminal of transistor Q6, the third terminal of transistor Q6 is connected to the third terminal of transistor Q5, and the second terminal of transistor Q6 is connected to ground GNDA.

[0038] Optionally, the transistors M1 to M17 may be MOSFETs; the first terminal of each transistor is its drain, the second terminal of each transistor is its source, and the third terminal of each transistor is its gate.

[0039] More specifically, the transistor M1 , the transistor M7 , the transistor M8 , the transistor M9 , the transistor M10 , the transistor M11 , the transistor M12 , and the transistor M13 are N-type MOSFETs.

[0040] More specifically, the transistor M2 , the transistor M3 , the transistor M4 , the transistor M5 , the transistor M6 , the transistor M14 , the transistor M15 , the transistor M16 , and the transistor M17 are P-type MOSFETs.

[0041] Optionally, transistors Q0 to Q7 are NPN transistors, and the current amplification factor is β.

[0042] More specifically, the first end of each transistor is its collector, the second end of each transistor is its emitter, and the third end of each transistor is its base.

[0043] More specifically, in the startup unit 11, the resistor R0, the transistor M3, the transistor Q0, the transistor Q1, and the resistor R1 form a startup branch; the transistor Q2 is a current injection tube that injects current during startup; BG After establishment, transistor M1 acts as a feedback tube to feed back the current flowing through transistor M7 and transistor M8; transistor M3 provides bias voltage for transistor M5 and transistor M6; transistor M2 and transistor M4 are switching tubes to control the start and shutdown of the low-temperature drift reference circuit; transistor M17 and transistor M18 are switching tubes to control the switching characteristics of the low-temperature drift reference circuit.

[0044] More specifically, in reference core unit 12, transistors M5 and M6 are added as folded cascode transistors to improve the loop gain of the reference. Transistors M7 and M8 form a linear current mirror, ensuring current matching between transistors Q3 and Q4 in reference core unit 12. Transistor M9, resistors R4, and resistors R5 form a common-source amplifier stage, further improving the loop gain. Capacitor C1 acts as a Miller compensation capacitor to ensure the stability of the negative feedback loop. Transistor M16 is a switching transistor that controls the switching characteristics of the low-temperature drift reference circuit. Furthermore, resistors R4 and R5 can also serve as voltage dividers to provide different reference voltages.

[0045] More specifically, in the base current absorption unit 13, transistor M12 is a current copying tube; transistor Q5 is a base current amplifying tube; transistor Q6 is a copying tube; transistor Q7 is a biasing tube; transistor M10, transistor M11, transistor M13, transistor M14 and transistor M15 are base current transmission tubes; and resistor R6 is an output resistor.

[0046] At the reference voltage V BG Before establishment, the drive signal EN is pulled down, the drive signal ENB is at a high level, transistor M2 is turned off, and the first and third terminals of transistor M3 are disconnected. At this point, the startup branch is in an open state. Transistors M18 and M17 are turned on, node VD is pulled down to zero, and node VSTART is pulled to ground. The shutdown current is zero, and the power consumption of the entire low-temperature drift reference circuit is approximately zero. After the drive signal EN is pulled high, the drive signal ENB is at a low level, the startup branch is pre-established, transistor M2 is turned on, and a bias voltage exists at node VD. The startup branch injects current into the bases of transistors Q3 and Q4 through transistor Q2. Node VSTART is the third terminal of transistor Q0, and node VD is the third terminal of transistor M3.

[0047] Furthermore, on the basis of zero turn-off current, the reliability of the startup unit 11 mainly depends on the injection characteristics of the transistor Q2 and the clamping function of the transistors Q0 and Q1. In order to make the voltage of the node VSTART and the voltage of the first end V4 of the second resistor network 122 approximately equal, the resistance values ​​of the resistor R1 and the resistor R3 are approximately equal. After the driving signal EN is pulled high, the voltage of the node VSTART is approximately 2V. BE +I Q1 *R1, the base voltage of transistor Q3 and transistor Q4 is V BE +I Q3 *R1, at this time, the emitters of transistors Q3 and Q4 are in a forward biased state, and the gate voltages of transistors M5 and M6 are established accordingly, so the gates of transistors M7 and M8 are pulled low, and the currents of the two core branches of transistors Q3 and Q4 begin to establish. At this time, the current starts to increase from zero. The emitter area ratio of Q3 and Q4 is 1:8, and the width-to-length ratio of transistors M7 and M8 is the same. The currents of the two core branches enter a positive feedback state, and the low-temperature drift reference circuit begins to start reliably. After the current gradually increases, resistor R2 causes the reference core unit 12 to enter a negative feedback state, and the reference voltage V BG Stable establishment. Among them, V BE is the base-emitter voltage of the transistor, I Q1 is the emitter current of transistor Q1, I Q3 is the emitter current of transistor Q3.

[0048] At the reference voltage V BG After stabilization is established, the current flowing through transistor M12 is the same as the current flowing through transistors M7 and M8. Transistor Q5 performs a reverse amplification function for the emitter current of transistors Q3 and Q4. Transistor M13 transmits the base current of transistor Q5 and injects it into the bases of transistors Q3 and Q4 in reference core unit 12, achieving current compensation characteristics. Compared with traditional reference circuits, this approach eliminates the accuracy error caused by base current to the reference voltage. Within the temperature range of -55°C to 150°C, the transistors' amplification coefficients β vary, and the reverse amplification function of base current sink unit 13 can adapt to changes in ambient temperature.

[0049] Further, Figure 2FIG1 shows a circuit diagram of a specific embodiment of the first resistor network 121, wherein the first resistor network 121 is a T-shaped symmetrically distributed resistor network, including resistors R31, R32, R33, R34, R35, R36, and R37. The first end of the resistor R31 is the first end V1 of the first resistor network 121, the second end of the resistor R31 is connected to the first end of the resistor R32, the second end of the resistor R32 is the fourth end V8 of the first resistor network 121, the first end of the resistor R33 is connected to the first end of the resistor R31, and the resistor R37 is connected to the first end of the resistor R31. The second end of resistor R33 is connected to the second end of resistor R32, the first end of resistor R34 is connected to the fourth end V8 of the first resistor network 121, the second end of resistor R34 is connected to the first end of resistor R35, the second end of resistor R35 is connected to the second end V2 of the first resistor network 121, the first end of resistor R36 is connected to the first end of resistor R34, the second end of resistor R36 is connected to the second end of resistor R35, the first end of resistor R37 is connected to the fourth end V8 of the first resistor network 121, and the second end of resistor R37 is connected to the third end V3 of the first resistor network 121. The current flowing through the first end V1 of the first resistor network 121 is I1, the current flowing through the second end V2 of the first resistor network 121 is I2, the current flowing through the third end V3 of the first resistor network 121 is I3, and the current flowing through the fourth end V8 of the first resistor network 121 is I8.

[0050] More specifically, the resistors R32 , R33 , R35 , R36 , and R37 are positive temperature coefficient resistors.

[0051] More specifically, the resistors R32 , R33 , R35 , R36 , and R37 may be of the same type.

[0052] More specifically, the resistors R31 and R34 are negative temperature coefficient resistors.

[0053] More specifically, the resistors R31 and R34 may be of the same type.

[0054] More specifically, the resistance values ​​of the resistors in the first resistor network 121 are symmetrically equal, that is, the resistance values ​​of the resistor R31 and the resistor R34 are equal, the resistance values ​​of the resistor R32 and the resistor R35 are equal, and the resistance values ​​of the resistor R33 and the resistor R36 are equal.

[0055] More specifically, the resistance of the resistor R37 is equal to that of the resistor R3.

[0056] Optionally, the resistor R37 may be a controllable resistor for generating a positive temperature coefficient voltage.

[0057] Furthermore, Figure 3 A circuit diagram of a specific embodiment of the second resistor network 122 is shown. Figure 3As shown, the second resistor network 122 includes resistors R41, R42, R43, and R44. The first end of resistor R42 is connected to the first end V4 of the second resistor network 122. The second end of resistor R42 is connected to the first ends of resistors R41, R43, and R44. The second end of resistor R44 is connected to the second end V5 of the second resistor network 122. The second end of resistor R43 is connected to the third end V6 of the second resistor network 122. The second end of resistor R41 is connected to the fourth end V7 of the second resistor network 122. The current flowing through the first end V4 of the second resistor network 122 is I4, the current flowing through the second end V5 of the second resistor network 122 is I5, the current flowing through the third end V6 of the second resistor network 122 is I6, and the current flowing through the fourth end V7 of the second resistor network 122 is I7.

[0058] More specifically, the equivalent resistance of the fourth terminal V8 seen from the first terminal V1 of the first resistor network 121 and the second terminal V2 of the first resistor network 121 is equal. Using unilateral circuit analysis, the resistance R37 is set to zero, and the equivalent resistance R from the first terminal V1 of the first resistor network 121 and the second terminal V2 of the first resistor network 121 to the fourth terminal V8 is derived. eq The expression:

[0059] .

[0060] More specifically, in this application, based on the principle of first-order linear compensation, the base-emitter voltage V BE And the change of the base-emitter voltage of the transistor with temperature ΔV BE The principle of superposition is used to achieve temperature coefficient compensation, and the reference voltage V BG The output waveform is approximately a quadratic parabola, where ΔV BE It is the change in the base-emitter voltage difference of the transistor with temperature.

[0061] In the traditional Brokaw reference circuit, the first terminal V1, the second terminal V2, and the third terminal V3 of the first resistor network 121 are short-circuited, and the first terminal V4 and the second terminal V5 of the second resistor network 122 are short-circuited, thereby obtaining the traditional reference voltage V BG The expression is:

[0062] .

[0063] Further, combined with Figure 1 The first resistor network 121 in the present application obtains the reference voltage V BG The expression is:

[0064] ,

[0065] The sum of the first two terms in the above equation is the bandgap reference voltage; the third term is the third positive temperature coefficient offset term introduced by the first resistor network 121 , which is composed of transistor Q3 , transistor Q4 and resistor R2 .

[0066] Furthermore, the expressions of the resistors R32 and R33 are as follows:

[0067] ],

[0068] in, and are the first-order temperature coefficients of resistors R32 and R31, respectively. 32,0 is the resistance of resistor R32 at the initial temperature T0, R 31,0 is the resistance of resistor R31 at the initial temperature T0, and T is the current temperature.

[0069] More specifically, the equivalent resistance R of the fourth terminal V8 seen from the first terminal V1 of the first resistor network 121 and the second terminal V2 of the first resistor network 121 is eq The expression can be simplified as follows:

[0070]

[0071] .

[0072]

[0073] Therefore, the expression of the third positive temperature coefficient offset term introduced by the first resistor network 121 is:

[0074] .

[0075] Furthermore, the above formula can be understood as adjusting the linear term on the basis of the quadratic parabola, and the reference voltage V BG It always has the characteristics of a quadratic function curve, but it is different from the traditional reference voltage V BG In comparison, the introduction of the third positive temperature coefficient offset term makes the reference voltage V BG The relative zero temperature point has shifted.

[0076] Furthermore, the second resistor network 122 performs secondary compensation based on the zero temperature point offset and introduces a constant term to achieve the low temperature drift characteristic of the reference circuit of the present application. Figure 1 and Figure 3As shown, a first end of resistor R42 is connected to the base of transistor Q3, a second end of resistor R44 is connected to the base of transistor Q4, a second end of resistor R43 is connected to the first end of transistor M15, and a second end of resistor R41 is connected to the first end of transistor M11. The current flowing through resistors R42 and R44 is the base compensation current.

[0077] Furthermore, the collector current of transistor Q3 in the reference core unit 12 is , transistor M5 works in the saturation region, the copy ratio of transistor M7 and transistor M12 is 1:1, so the collector current of transistor Q5 is In order to ensure that transistor Q5 works in the amplification area, transistor Q7 provides bias voltage for transistor Q5 and transistor Q6. The base currents of transistor Q5 and transistor Q6 are both , the base current of transistor Q7 can be approximately ignored, so the channel current of transistor M13 is , this current is twice the base current of transistor Q3 and transistor Q4. Assuming that the current copy ratio from transistor M13 to transistor M11 is 1:N, it is converted to the current mirror composed of transistor M14 and transistor M15 through transistor M13 and transistor M10, where the current copy ratio from transistor M13 to transistor M15 is 1:K.

[0078] In order to achieve base current compensation of transistors Q3 and Q4 and reduce the temperature drift coefficient, the selection of parameters N and K needs to compensate for the third positive temperature coefficient offset term of the first resistor network 121.

[0079] Among them, the collector current of transistor Q3 is:

[0080]

[0081] In the second resistor network 122, the first terminal V4 is a reference voltage, and the voltage expression from the fourth terminal V7 to the first terminal V4 or the second terminal V5 is:

[0082]

[0083]

[0084] In the above formula , where M represents the direct compensation introduced by the base current, K represents the copy ratio of the base compensation current, and N represents the compensation amount of the reference voltage. The reference voltage V can be derived BG The expression is

[0085]

[0086] The sum of the first two terms in the above formula is the bandgap reference voltage, and the difference between the base-emitter voltage of a transistor with a positive temperature coefficient changes with temperature. and the base-emitter voltage of a transistor with a negative temperature coefficient The linear superposition of the first linear term produces the third term, which is the third positive temperature coefficient offset term, The fourth term is the low-order compensation term of The negative temperature coefficient accounts for a large proportion of the high-order compensation terms. Low-order compensation can be achieved by adjusting the resistance values ​​of resistors R31 and R32, and high-order compensation can be achieved by adjusting the resistance values ​​of M, N, resistors R41, and resistors R42, so that when the temperature changes, the sum of the terms in the above formula is the reference voltage V BG Remain unchanged or change very little, thus achieving low temperature drift.

[0087] Therefore, the low temperature drift reference circuit of the present application is based on the traditional Brokaw structure, combined with the base current compensation idea, using a T-type resistor network, based on the principle of Taylor expansion. A new reference voltage expression is obtained by transforming at different temperature points. It relies on the positive temperature coefficient offset term to compensate for the negative temperature coefficient voltage, which can further improve the temperature drift characteristics of the reference and thus achieve low temperature drift.

[0088] Figure 4 FIG. 1 is a circuit diagram of a second specific embodiment of a low-temperature drift reference circuit according to the present invention. Figure 4As shown, in this specific embodiment, the startup unit 21 includes multiple resistors, multiple transistors, and multiple triodes. The voltage VDDA is connected to the first end and the third end of the transistor M21 through the resistor R20. The second end of the transistor M21 is connected to the first end and the third end of the triode Q20. The second end of the triode Q20 is connected to the first end and the third end of the triode Q21. The second end of the triode Q21 is grounded to GNDA. The first end of the transistor M22 is connected to the voltage VDDA. The third end of the transistor M22 is connected to the third end of the transistor M21. The second end of the transistor M23 is connected to the voltage VDDA. The first end of the transistor M23 is connected to the voltage VDDA. The second end of the transistor M25 is connected to the first end and the third end of the transistor M27. The third end of the transistor M27 is connected to the second end of the transistor M22. The second end of the transistor M27 is connected to the first end and the third end of the transistor Q22. The second end of the transistor Q22 is grounded to GNDA. The second end of the transistor M24 is at a voltage VDDA. The third end of the transistor M24 is connected to the third end of the transistor M23 and the first end of the transistor M26. The first end of the transistor M24 is connected to the second end of the transistor M26. The third end of the transistor M26 is connected to the third end of the transistor M25. The transistor M2 The first end of transistor M6 is connected to the third end of transistor M26 and the first end of transistor M28 through resistor R21. The third end of transistor M28 is connected to the third end of transistor M27. The second end of transistor M28 is connected to the first end of transistor Q23. The third end of transistor Q23 is connected to the third end of transistor Q22. The second end of transistor Q23 is grounded to GNDA through resistor R22. The second end of transistor M0 is connected to voltage VDDA. The third end of transistor M0 is connected to the third end of transistor M24. The first end of transistor M0 is connected to the first end of transistor M2. The first end of transistor M2 is connected to the first end of transistor M3. The second end of transistor M3 is connected to the first and third ends of transistor Q0, the third end of transistor M3 is connected to the second end of transistor M2, the second end of transistor Q0 is connected to the first and third ends of transistor Q1, the second end of transistor Q1 is connected to ground GNDA via resistor R1, the third end of transistor Q0 is connected to the third end of transistor Q2, the first end of transistor Q2 is connected to voltage VDDA, the second end of transistor Q2 is connected to the first end of transistor M17, the second end of transistor M17 is connected to ground GNDA, the third end of transistor Q0 is connected to the first end of transistor M4, and the second end of transistor M4 is connected to ground GNDA. The third end of transistor M2 is connected to a drive signal EN, and the third ends of transistors M4 and M17 are connected to a drive signal ENB, where the drive signal EN is opposite to the drive signal ENB.

[0089] Optionally, the transistors M2 to M17 may be MOSFETs; the first terminal of each transistor is its drain, the second terminal of each transistor is its source, and the third terminal of each transistor is its gate.

[0090] More specifically, the transistor M1 , the transistor M7 , the transistor M8 , the transistor M9 , the transistor M10 , the transistor M11 , the transistor M12 , and the transistor M13 are N-type MOSFETs.

[0091] More specifically, the transistor M2 , the transistor M3 , the transistor M4 , the transistor M5 , the transistor M6 , the transistor M14 , the transistor M15 , the transistor M16 , and the transistor M17 are P-type MOSFETs.

[0092] Optionally, the transistor M0 and the transistors M21 to M28 may be MOSFETs; the first terminal of each transistor is its drain, the second terminal of each transistor is its source, and the third terminal of each transistor is its gate.

[0093] More specifically, the transistor M0 , the transistor M23 , the transistor M24 , the transistor M25 , and the transistor M26 are N-type MOSFETs.

[0094] More specifically, the transistor M21 , the transistor M22 , the transistor M27 , and the transistor M28 are P-type MOSFETs.

[0095] Optionally, the transistors Q20 to Q23 are NPN transistors, and the current amplification factors are all β.

[0096] More specifically, the first end of each transistor is its collector, the second end of each transistor is its emitter, and the third end of each transistor is its base.

[0097] exist Figure 4 In a specific embodiment, resistor R20, transistor M21, transistor Q20, and transistor Q21 constitute a startup branch; transistor Q22 and transistor Q23 constitute a 1:8 current definition transistor; resistor R22 is used to define the current of the two bias branches where transistors Q22 and Q23 are located; transistors M27 and M28 constitute a cascode structure; transistor M23, transistor M24, transistor M25, and transistor M26 constitute a low-voltage cascode structure for copying current; resistor R21 provides a bias voltage for transistors M23 to M26.

[0098] At startup, the startup branch is pre-established, wherein the gate voltage of transistor M21 is defined as the pre-start voltage, which is approximately 2V. BE +V GS21 , where V GS21is the gate-source voltage of transistor M21; the bases of transistors Q22 and Q23, and the gates of transistors M27 and M28 are all at zero potential; when voltage VDDA is greater than the pre-start voltage, current flows in the start-up branch, and transistor M22 operates in the saturation region, injecting current into the two bias branches. At this time, the current in the bias branch is very small, entering a positive feedback loop.

[0099] During the establishment of the two bias currents, the gate voltage of transistor M22 remains approximately unchanged, which is expressed as 2V BE +V GS21 ; Transistor M27 operates approximately in the subthreshold region, and the gate voltage is equal to V BE +V GS27 , V GS27 is the gate-source voltage of transistor M27; the gate-source voltage of transistor M22 is V GS22 =V BE +V GS21 -V GS27 , where transistors M21, M22, M27, and M28 have the same size, V GS21 = V GS27 , then the gate-source voltage V GS22 =V BE , and V BE >0, so when the voltage VDDA is greater than the pre-start voltage, the two bias currents begin to build up. As the current continues to increase, the current of transistor M22 gradually decreases, and transistor M22 exits the saturation region. The current gradually decreases to zero, and the gate-source voltage V GS22 =V BE <Threshold voltage V TH , the transistor M22 is turned off. After the transistor M22 is turned off, the drain-source current I DS22 =0, the branch injecting current is in a completely shut-off state.

[0100] Among them, the gate of transistor M0 is connected to the gate of transistor M23 and transistor M24, forming a linear current mirror to copy the two bias currents. After the power supply voltage is established, the branch is started. At this time, the drive signal EN is at zero potential, and transistor M0 operates in the deep linear region; after the drive signal EN is pulled high, the bias branch where transistor M0 is located begins to be established, and current flows through it. After the voltage of node VD is established, current is injected into the reference core unit 22, and transistor M0 finally operates in the saturation region. Compared to Figure 1 In the specific embodiment, Figure 4 The specific embodiment uses transistor M0 to replace resistor R0 to realize the injection of startup current, which can further realize a high-reliability startup process of the circuit.

[0101] for Figure 4In the startup unit 21, in different power supply voltage ranges, the resistor R20 mainly determines the current of the startup branch. According to the base emitter current I BE and the base-emitter voltage V BE The E exponential relationship, in the microampere current range, the voltage V BE The change is very small and has no effect on the startup of the chip, thus solving the problem of high-reliability startup of the chip within different power supply voltage ranges and simplifying the circuit design. Figure 1 Compared with the starting unit in Figure 4 The starting unit in the system can meet the high reliability starting requirements under high and low voltage conditions.

[0102] Furthermore, Figure 4 The core unit 22 and Figure 1 The structure and function of the middle reference core unit 12 are the same and will not be described again here.

[0103] Furthermore, Figure 4 The base current absorption unit 23 and Figure 1 The structure and function of the middle base current sink unit 13 are the same and will not be described again here.

[0104] Furthermore, Figure 4 The first resistor network 221 and Figure 1 The structure and function of the first resistor network 121 are the same as those in the embodiment, and are not described again here.

[0105] Furthermore, Figure 4 The second resistor network 222 and Figure 1 The structure and function of the second resistor network 122 are the same and will not be described again here.

[0106] In summary, the low-temperature drift reference circuit provided by this application is based on a traditional Brokaw structure, combined with a base current compensation concept. It employs a T-type resistor network, relies on a positive temperature coefficient voltage expansion term, and compensates for a negative temperature coefficient voltage, thereby obtaining a low-temperature drift reference voltage. By changing the resistor type and value of the resistor network and the proportional relationship of the current mirror, the magnitude of the reference voltage can be adjusted. Furthermore, the circuit of the present invention utilizes a conventional BCD process design to achieve a reference voltage with a low temperature drift coefficient within the range of -55°C to 150°C, meeting the reference voltage requirements of analog chips and improving the chip's voltage accuracy and temperature drift coefficient. Furthermore, it can achieve a very small chip size (DIE SIZE), saving process costs, and is suitable for both high- and low-voltage applications.

[0107] Figure 5 This is the simulation waveform of the traditional Brokaw bandgap reference circuit. In the range of -55℃-150℃, the temperature drift coefficient can reach 25ppm. Figure 6This is the simulation waveform of the low-temperature drift reference circuit of this application. The temperature drift coefficient can be improved to about 16ppm.

[0108] Figure 7 This is a simulation waveform diagram of the low-temperature drift reference circuit of this application when the driving signal EN changes from low to high. It can be seen from the figure that when the driving signal EN is pulled low, the start branch is reliably turned off, and the current I BG The power consumption of the low-temperature drift reference circuit of the present application is zero; when the driving signal EN is pulled high, the reference core unit is gradually established and reaches a stable state, and the current I of the entire low-temperature drift reference circuit is BG It is 28.49μA.

[0109] Figure 8 is the reference voltage V at different temperatures BG The waveform of the reference voltage V in different temperature ranges BG The minimum value after stabilization is approximately between 2.00V and 2.20V, which can meet most application scenarios.

[0110] Although the present invention has been disclosed above with reference to the embodiments, they are not intended to limit the present invention. Anyone with ordinary skill in the art may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent applications.

Claims

1. A low temperature drift reference circuit, characterized in that: The device comprises a startup unit, a reference core unit, and a base current absorption unit, wherein the startup unit is connected to the reference core unit and the base current absorption unit, and the reference core unit is connected to the base current absorption unit; The reference core unit includes a plurality of transistors, a plurality of triodes, a plurality of resistors, a first resistor network, and a second resistor network. The second end of the seventh transistor is connected to the first voltage, the first end of the seventh transistor is connected to the third end of the seventh transistor and the first end of the fifth transistor, the second end of the fifth transistor is connected to the first end of the third triode, the second end of the third triode is connected to the first end of the first resistor network, the third end of the first resistor network is grounded via a third resistor, the second end of the eighth transistor is connected to the first voltage, the third end of the eighth transistor is connected to the third end of the seventh transistor and the third end of the first transistor, the first end of the eighth transistor is connected to the first end of the sixth transistor, the third end of the sixth transistor is connected to the third end of the fifth transistor and the third end of the third transistor, and the third end of the sixth transistor is connected to the first end of the fourth triode. The second end of the fourth transistor is connected to the second end of the first resistor network via the second resistor. The third ends of the fifth transistor and the sixth transistor are further connected to the first end of the eighteenth transistor. The second end of the eighteenth transistor is grounded. The first end of the second resistor network is connected to the third end of the third transistor and the second end of the second transistor. The second end of the second resistor network is connected to the third end of the fourth transistor. The second end of the ninth transistor is connected to the first voltage. The first end of the ninth transistor is connected to the first end of the fourth resistor. The second end of the fourth resistor is connected to the first end of the fifth resistor. The second end of the fifth resistor is grounded. The third end of the ninth transistor is connected to the first end of the eighth transistor. The first capacitor is connected between the first and third ends of the ninth transistor. The fourth end of the second resistor network is connected to the first end of the sixteenth transistor. The second end of the sixteenth transistor is grounded. The first resistor network includes a thirty-first resistor, a thirty-second resistor, a thirty-third resistor, a thirty-fourth resistor, a thirty-fifth resistor, a thirty-sixth resistor, and a thirty-seventh resistor, wherein a first end of the thirty-first resistor is connected to the first end of the first resistor network, a second end of the thirty-first resistor is connected to the first end of the thirty-second resistor, and a second end of the thirty-second resistor is connected to the first end of the second resistor network, a first end of the thirty-third resistor is connected to the first end of the thirty-first resistor, and a second end of the thirty-third resistor is connected to the second end of the thirty-second resistor, a first end of the thirty-fourth resistor is connected to the first end of the second resistor network, and a second end of the thirty-fourth resistor is connected to the first end of the thirty-fifth resistor, and a second end of the thirty-fifth resistor is the second end of the first resistor network, a first end of the thirty-sixth resistor is connected to the first end of the thirty-fourth resistor, and a second end of the thirty-sixth resistor is connected to the second end of the thirty-fifth resistor, a first end of the thirty-seventh resistor is connected to the first end of the second resistor network, and a second end of the thirty-seventh resistor is the third end of the first resistor network; The second resistor network includes a forty-first resistor, a forty-second resistor, a forty-third resistor, and a forty-fourth resistor. The first end of the forty-second resistor is the first end of the second resistor network. The second end of the forty-second resistor is connected to the first ends of the forty-first resistor, the forty-third resistor, and the forty-fourth resistor. The second end of the forty-fourth resistor is the second end of the second resistor network. The second end of the forty-third resistor is the third end of the second resistor network. The second end of the forty-first resistor is the fourth end of the second resistor network.

2. A low temperature drift reference circuit as claimed in claim 1, characterized in that: The startup unit includes multiple resistors, multiple transistors, and multiple triodes. The first voltage is connected to the first end of the second transistor through the zeroth resistor, the second end of the second transistor is connected to the first end of the first transistor, the second end of the first transistor is connected to the first voltage, the first end of the second transistor is connected to the first end of the third transistor, the second end of the third transistor is connected to the first end and the third end of the zeroth triode, the third end of the third transistor is connected to the first end of the first transistor, the second end of the zeroth triode is connected to the first end and the third end of the first triode, the second end of the first triode is grounded through the first resistor, the third end of the zeroth triode is connected to the third end of the second triode, the first end of the second triode is connected to the first voltage, the second end of the second triode is connected to the first end of the seventeenth transistor, the second end of the seventeenth transistor is grounded, the third end of the zeroth triode is connected to the first end of the fourth transistor, and the second end of the fourth transistor is grounded.

3. A low temperature drift reference circuit as claimed in claim 2, characterized in that: The startup unit includes multiple resistors, multiple transistors, and multiple triodes. The first voltage is connected to the first end and the third end of the twenty-first transistor through the twentieth resistor. The second end of the twenty-first transistor is connected to the first end and the third end of the twenty-third transistor. The second end of the twenty-third transistor is connected to the first end and the third end of the twenty-first triode. The second end of the twenty-first triode is grounded. The first end of the twenty-second transistor is connected to the first voltage. The third end of the twenty-second transistor is connected to the third end of the twenty-first transistor. The second end of the twenty-third transistor is connected to the first voltage. The first end of the twenty-third transistor is connected to the second end of the twenty-fifth transistor. The first end of the twenty-fifth transistor is connected to the first end and the third end of the twenty-seventh transistor. The third end of the twenty-seventh transistor is connected to the second end of the twenty-second transistor. The second end of the twenty-seventh transistor is connected to the first end and the third end of the twenty-second triode. The second end of the twenty-second triode is grounded. The second end of the twenty-fourth transistor is connected to the first voltage. The third end of the twenty-fourth transistor is connected to the third end of the twenty-third transistor and the first end of the twenty-sixth transistor. The first end of the twenty-fourth transistor is connected to the second end of the twenty-sixth transistor. The third end of the twenty-sixth transistor is connected to the third end of the twenty-fifth transistor. The first end of the sixteenth transistor is connected to the third end of the twenty-sixth transistor and the first end of the twenty-eighth transistor through the twenty-first resistor, the third end of the twenty-eighth transistor is connected to the third end of the twenty-seventh transistor, the second end of the twenty-eighth transistor is connected to the first end of the twenty-third transistor, the third end of the twenty-third transistor is connected to the third end of the twenty-second transistor, the second end of the twenty-third transistor is grounded through the twenty-second resistor, the second end of the zeroth transistor is connected to the first voltage, the third end of the zeroth transistor is connected to the third end of the twenty-fourth transistor, the first end of the zeroth transistor is connected to the first end of the second transistor, and the One end is connected to the first end of the third transistor, the second end of the third transistor is connected to the first end and the third end of the zeroth transistor, the third end of the third transistor is connected to the second end of the second transistor, the second end of the zeroth transistor is connected to the first end and the third end of the first transistor, the second end of the first transistor is grounded through the first resistor, the third end of the zeroth transistor is connected to the third end of the second transistor, the first end of the second transistor is connected to the first voltage, the second end of the second transistor is connected to the first end of the seventeenth transistor, the second end of the seventeenth transistor is grounded, the third end of the zeroth transistor is connected to the first end of the fourth transistor, and the second end of the fourth transistor is grounded.

4. A low temperature drift reference circuit as claimed in claim 2 or 3, characterized in that: The base current absorption unit includes multiple resistors, multiple transistors, and multiple triodes. The second end of the tenth transistor is connected to the first voltage, the first end of the tenth transistor is connected to the first end and the third end of the fourteenth transistor, the second end of the fourteenth transistor is grounded, the third end of the fourteenth transistor is connected to the third end of the fifteenth transistor, the first end of the fifteenth transistor is connected to the third end of the second resistor network, the second end of the fifteenth transistor is grounded, the second end of the eleventh transistor is connected to the first voltage, the first end of the eleventh transistor is connected to the fourth end of the second resistor network, the second end of the twelfth transistor is connected to the first voltage, the third end of the twelfth transistor is connected to the seventh transistor and the eighth transistor. The first end of the twelfth transistor is connected to the first end of the fifth triode, the second end of the fifth triode is grounded, the second end of the thirteenth transistor is connected to the first voltage, the third end of the thirteenth transistor is connected to the second end of the thirteenth transistor and the third end of the tenth transistor, the second end of the thirteenth transistor is connected to the first end of the seventh triode, the third end of the seventh triode is connected to the first end of the twelfth transistor, the second end of the seventh triode is connected to the third end of the fifth triode, the second end of the sixth resistor is connected to the first voltage, the second end of the sixth resistor is connected to the first end of the sixth triode, the third end of the sixth triode is connected to the third end of the fifth triode, and the second end of the sixth triode is grounded.

5. A low temperature drift reference circuit as claimed in claim 4, characterized in that: Reference voltage V BG The expression is Among them, V BE is the base-emitter voltage of the transistor, ΔV BE is the change of the base-emitter voltage of the transistor with temperature, R3 is the resistance of the third resistor, R2 is the resistance of the second resistor, R eq is the equivalent resistance, β is the current amplification factor of the transistor, M represents the direct compensation amount introduced by the base current, N represents the compensation amount of the reference voltage, R42 is the resistance value of the forty-second resistor, and R41 is the resistance value of the forty-first resistor.

6. A low temperature drift reference circuit as claimed in claim 1, characterized in that: The thirty-second resistor, the thirty-third resistor, the thirty-fifth resistor, the thirty-sixth resistor, and the thirty-seventh resistor are positive temperature coefficient resistors; the thirty-first resistor and the thirty-fourth resistor are negative temperature coefficient resistors.

7. A low temperature drift reference circuit as claimed in claim 1, characterized in that: The thirty-seventh resistor is a controllable resistor. 8 . The low-temperature drift reference circuit according to claim 1 , wherein the resistance of the thirty-seventh resistor is equal to that of the third resistor.

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