Low-temperature drift reference circuit

Abstract

The invention discloses a low-temperature drift reference circuit, which belongs to the technical field of electronic circuits and comprises a starting unit, a reference core unit and a base current absorption unit, the starting unit is connected with the reference core unit and the base current absorption unit, and the reference core unit is connected with the base current absorption unit. According to the low-temperature-drift reference circuit, the T-type resistor network is adopted, negative temperature coefficient voltage is compensated depending on a positive temperature coefficient voltage expansion item, and low-temperature-drift reference voltage can be obtained; the magnitude of the reference voltage can be adjusted by changing the proportional relation between the resistance type and the resistance value of the resistance network and the current mirror.

Description

Technical Field

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

[0002] The reference voltage source is a key module in modern analog hybrid circuit design. With the continuous change of application scenarios, there is a higher-precision requirement for the reference voltage source in analog chips, that is, a lower temperature coefficient requirement in a wider temperature range.

[0003] In the existing CMOS bandgap reference circuit, 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 mostly concentrates on 50ppm. In addition, an NPN structure is also adopted in this reference circuit, and the base current directly affects its temperature drift coefficient.

[0004] In the existing bandgap reference circuit with PMOS output, the gain of the loop is further increased, but the load-carrying capacity of the output is sacrificed. In addition, its temperature drift coefficient also mostly concentrates on 50ppm.

[0005] Therefore, how to achieve a 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 as follows: A low-temperature drift reference circuit includes 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; 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 terminal of the seventh transistor is connected to the first voltage, the first terminal of the seventh transistor is connected to the third terminal of the seventh transistor and the first terminal of the fifth transistor, the second terminal of the fifth transistor is connected to the first terminal of the third triode, the second terminal of the third triode is connected to the first terminal of the first resistor network, and the third terminal of the first resistor network is grounded through the third resistor. The second terminal of the eighth transistor is connected to the first voltage, the third terminal of the eighth transistor is connected to the third terminal of the seventh transistor and the third terminal of the first transistor, the first terminal of the eighth transistor is connected to the first terminal of the sixth transistor, the third terminal of the sixth transistor is connected to the third terminal of the fifth transistor and the third terminal of the third transistor, the third terminal of the sixth transistor is connected to the first terminal of the fourth triode, the second terminal of the fourth triode is connected to the second terminal of the first resistor network through the second resistor, and the third terminals of the fifth transistor and the sixth transistor are further connected to the first terminal of the eighteenth transistor, and the second terminal of the eighteenth transistor is grounded. The first terminal of the second resistor network is connected to the third terminal of the third triode and the second terminal of the second triode, the second terminal of the second resistor network is connected to the third terminal of the fourth triode, the second terminal of the ninth transistor is connected to the first voltage, the first terminal of the ninth transistor is connected to the first terminal of the fourth resistor, the second terminal of the fourth resistor is connected to the first terminal of the fifth resistor, and the second terminal of the fifth resistor is grounded. The third terminal of the ninth transistor is connected to the first terminal of the eighth transistor, and the first capacitor is connected between the first terminal and the third terminal of the ninth transistor. The fourth terminal of the second resistor network is connected to the first terminal of the sixteenth transistor, and the second terminal of the sixteenth transistor is grounded.

[0008] 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 terminal of the thirty-first resistor is the first terminal of the first resistor network, the second terminal of the thirty-first resistor is connected to the first terminal of the thirty-second resistor, the second terminal of the thirty-second resistor is connected to the first terminal of the second resistor network, the first terminal of the thirty-third resistor is connected to the first terminal of the thirty-first resistor, the second terminal of the thirty-third resistor is connected to the second terminal of the thirty-second resistor, the first terminal of the thirty-fourth resistor is connected to the first terminal of the second resistor network, the second terminal of the thirty-fourth resistor is connected to the first terminal of the thirty-fifth resistor, the second terminal of the thirty-fifth resistor is the second terminal of the first resistor network, the first terminal of the thirty-sixth resistor is connected to the first terminal of the thirty-fourth resistor, the second terminal of the thirty-sixth resistor is connected to the second terminal of the thirty-fifth resistor, the first terminal of the thirty-seventh resistor is connected to the first terminal of the second resistor network, and the second terminal of the thirty-seventh resistor is the third terminal of the first resistor network.

[0009] 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. The second end of the forty-first resistor is the fourth end of the second resistor network.

[0010] In a specific embodiment, the starting unit includes a plurality of resistors, a plurality of transistors, and a plurality of triodes. A first voltage is connected to the first end of a second transistor through a zeroeth resistor. The second end of the second transistor is connected to the first end of a 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 a third transistor. The second end of the third transistor is connected to the first end and the third end of a zeroeth triode. The third end of the third transistor is connected to the first end of the first transistor. The second end of the zeroeth triode is connected to the first end and the third end of a first triode. The second end of the first triode is grounded through a first resistor. The third end of the zeroeth triode is connected to the third end of a 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 a seventeenth transistor. The second end of the seventeenth transistor is grounded. The third end of the zeroeth triode is connected to the first end of a fourth transistor. The second end of the fourth transistor is grounded.

[0011] In a specific embodiment, the starting unit includes a plurality of resistors, a plurality of transistors, and a plurality of triodes. The first voltage is connected to the first and third ends of the twenty-first transistor through the twentieth resistor. The second end of the twenty-first transistor is connected to the first and third ends of the twenty-third triode. The second end of the twenty-third triode is connected to the first and third ends 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 and third ends 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 and third ends 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 triode. The third end of the twenty-third triode is connected to the third end of the twenty-second transistor. The second end of the twenty-third triode is grounded through the twenty-second resistor. The second end of the zero-th transistor is connected to the first voltage. The third end of the zero-th transistor is connected to the third end of the twenty-fourth transistor. The first end of the zero-th transistor is connected to the first end of the second transistor. 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 and third ends of the zero-th triode. The third end of the third transistor is connected to the second end of the second transistor. The second end of the zero-th triode is connected to the first and third ends of the first triode. The second end of the first triode is grounded through the first resistor. The third end of the zero-th 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 zero-th triode is connected to the first end of the fourth transistor. The second end of the fourth transistor is grounded.

[0012] In a specific embodiment, the base current absorption unit includes a plurality of resistors, a plurality of transistors, and a plurality of 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 third ends of 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.

[0013] In a specific embodiment, the reference voltage V BG has the expression of wherein, V BE is the base-emitter voltage of the triode, ΔV BE is the variation of the base-emitter voltage of the triode due to temperature, R3 is the resistance value of the third resistor, R2 is the resistance value of the second resistor, R eq is the equivalent resistance, β is the current amplification factor of the triode, 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.

[0014] 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; the thirty-first resistor and the thirty-fourth resistor are negative temperature coefficient resistors.

[0015] In a specific embodiment, the thirty-seventh resistor is a controllable resistor.

[0016] In a specific embodiment, the resistance value of the thirty-seventh resistor is equal to that of the third resistor.

[0017] Beneficial effects: The low-temperature drift reference circuit of the present invention is based on the traditional Brokaw structure, combines the base current compensation idea, adopts a T-shaped resistor network, relies on the positive temperature coefficient voltage expansion term to compensate the negative temperature coefficient voltage, and can obtain a reference voltage with low temperature drift; by changing the resistor type and resistance value of the resistor network and the proportional relationship of the current mirror, the magnitude of the reference voltage can be adjusted. In addition, the circuit of the present invention can be realized by using the conventional BCD process. In the range of -55°C to 150°C, a reference voltage with a small temperature drift coefficient can be obtained, which can meet the requirements of the reference voltage required in the analog chip, improve the voltage accuracy and temperature drift coefficient of the chip; in addition, a very small chip size (DIE SIZE) can also be achieved, saving the process cost; it is applicable to both high-voltage and low-voltage occasions.

[0018] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. is a schematic circuit diagram of a first specific embodiment of a low-temperature drift reference circuit of the present invention.

[0020] Figure 2 FIG. is a schematic circuit diagram of a specific embodiment of a first resistor network.

[0021] Figure 3 FIG. is a schematic circuit diagram of a specific embodiment of a second resistor network.

[0022] Figure 4 FIG. is a schematic circuit diagram of a second specific embodiment of a low-temperature drift reference circuit of the present invention.

[0023] Figure 5 FIG. is a simulation waveform diagram of a traditional Brokaw bandgap reference circuit.

[0024] Figure 6 FIG. is a simulation waveform diagram of the low-temperature drift reference circuit of the present application.

[0025] Figure 7 FIG. is a simulation waveform diagram of the low-temperature drift reference circuit of the present application when the driving signal EN changes from low to high.

[0026] Figure 8 For the reference voltage V BG Waveform. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives and technical solutions of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0028] The present invention provides a low-temperature-drift reference circuit, including 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.

[0029] More specifically, the startup unit injects current into the reference core unit to generate a reference voltage; the base current absorption unit injects current into the reference core unit to achieve current compensation, thereby obtaining a low-temperature-drift reference voltage.

[0030] Figure 1 FIG. 10 is a schematic circuit diagram of a first specific embodiment of a low-temperature-drift reference circuit according to the present invention. In this specific embodiment, the startup unit 11 includes a plurality of resistors, a plurality of transistors, and a plurality of triodes. The voltage VDDA is connected to the first end of the transistor M2 through the 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 grounded to GNDA through the 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 grounded to 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 grounded to GNDA. Among them, the third end of the transistor M2 is connected to the drive signal EN, and the third ends of the transistor M4 and the transistor M17 are connected to the drive signal ENB, and the drive signal EN and the drive signal ENB are opposite.

[0031] Among them, the voltage VDDA plays a power supply role.

[0032] Please continue to refer to Figure 1, in this specific embodiment, the reference core unit 12 includes a plurality of transistors, a plurality of triodes, a plurality of resistors, a first resistor network 121 and a second resistor network 122. The second terminal of transistor M7 is connected to voltage VDDA, the first terminal of transistor M7 is connected to the third terminal of transistor M7 and the first terminal of transistor M5. The second terminal of transistor M5 is connected to the first terminal of triode Q3. The second terminal of triode Q3 is connected to the first terminal V1 of the first resistor network 121. The third terminal V3 of the first resistor network 121 is grounded to GNDA through resistor R3. The second terminal of transistor M8 is connected to voltage VDDA. The third terminal of transistor M8 is connected to the third terminal of transistor M7 and the third terminal of transistor M1. The first terminal of transistor M8 is connected to the first terminal of transistor M6. The third terminal of transistor M6 is connected to the third terminal of transistor M5 and the third terminal of transistor M3. The third terminal of transistor M6 is connected to the first terminal of triode Q4. The second terminal of triode Q4 is connected to the second terminal V2 of the first resistor network 121 through resistor R2. The third terminals of transistor M5 and transistor M6 are also connected to the first terminal of transistor M18. The second terminal of transistor M18 is grounded to GNDA. The first terminal V4 of the second resistor network 122 is connected to the third terminal of triode Q3 and the second terminal of triode Q2. The second terminal V5 of the second resistor network 122 is connected to the third terminal of triode Q4. The second terminal of transistor M9 is connected to voltage VDDA. The first terminal of transistor M9 is connected to the first terminal of resistor R4. The second terminal of resistor R4 is connected to the first terminal of resistor R5. The second terminal of resistor R5 is grounded to GNDA. The third terminal of transistor M9 is connected to the first terminal of transistor M8. Capacitor C1 is connected between the first terminal and the third terminal of transistor M9. The fourth terminal V7 of the second resistor network 122 is connected to the first terminal of transistor M16. The second terminal of transistor M16 is grounded to GNDA. The fourth terminal V7 of the second resistor network 122 outputs a reference voltage V BG . Among them, the third terminals of transistor M18 and transistor M16 are connected to the drive signal ENB.

[0033] Please continue to refer to Figure 1, in this specific embodiment, the base current absorption unit 13 includes a plurality of resistors, a plurality of transistors, and a plurality of 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, the third end of the transistor M12 is connected to the third ends of the transistors M7 and M8, the first end of the transistor M12 is connected to the first end of the triode Q5, the second end of the triode Q5 is grounded to GNDA, the second end of the transistor M13 is connected to the voltage VDDA, the third end of the transistor M13 is connected to the second end of the transistor M13 and the third end of the transistor M10, the second end of the transistor M13 is connected to the first end of the triode Q7, the third end of the triode Q7 is connected to the first end of the transistor M12, the second end of the triode Q7 is connected to the third end of the triode Q5, the second end of the resistor R6 is connected to the voltage VDDA, the second end of the resistor R6 is connected to the first end of the triode Q6, the third end of the triode Q6 is connected to the third end of the triode Q5, and the second end of the triode Q6 is grounded to GNDA.

[0034] Optionally, the transistors M1 to M17 can be MOSFETs; the first end of each transistor is its drain, the second end of each transistor is its source, and the third end of each transistor is its gate.

[0035] More specifically, the transistors M1, M7, M8, M9, M10, M11, M12, and M13 are N-type MOSFETs.

[0036] More specifically, the transistors M2, M3, M4, M5, M6, M14, M15, M16, and M17 are P-type MOSFETs. Optionally, the triodes Q0 to Q7 are NPN-type triodes, and the current amplification factor is β for all of them.

[0037] More specifically, the first end of each triode is its collector, the second end of each triode is its emitter, and the third end of each triode is its base.

[0038] More specifically, in the startup unit 11, the resistor R0, the transistor M3, the triodes Q0, Q1, and the resistor R1 form a startup branch; the triode Q2 is a current injection tube that injects current during startup; wait for the reference voltage VBG After establishment, transistor M1 acts as a feedback transistor to feedback the current flowing through transistors M7 and M8; transistor M3 provides a bias voltage for transistors M5 and M6; transistors M2 and M4 are switching transistors to control the startup and shutdown of the low-temperature drift reference circuit; transistors M17 and M18 are switching transistors to control the switching characteristics of the low-temperature drift reference circuit.

[0039] More specifically, in the reference core unit 12, in order to improve the loop gain of the reference, transistors M5 and M6 are added as folded cascode transistors; transistors M7 and M8 form a linear current mirror to keep the currents in the branches of transistors Q3 and Q4 in the reference core unit 12 matched; transistors M9, resistor R4, and resistor R5 form a common-source amplifier stage, which can further improve 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 to control the switching characteristics of the low-temperature drift reference circuit. In addition, resistors R4 and R5 can also act as voltage-dividing resistors to provide different reference voltages.

[0040] More specifically, in the base current absorption unit 13, transistor M12 is a current copy transistor; transistor Q5 is a base current amplification transistor; transistor Q6 is a copy transistor; transistor Q7 is a bias transistor; transistors M10, M11, M13, M14, and M15 are base current transmission transistors; resistor R6 is an output resistor.

[0041] At the reference voltage V BG Before establishment, the driving signal EN is pulled down, the driving signal ENB is at a high level, transistor M2 is turned off, the first end and the third end of transistor M3 are disconnected, and the startup branch is in an open state at this time; transistors M18 and M17 are turned on, the node VD is pulled down to zero, and at the same time the node VSTART is pulled to the ground, the shutdown current is zero, and the power consumption of the entire low-temperature drift reference circuit is approximately zero. After the driving signal EN is pulled up, the driving signal ENB is at a low level, the startup branch is pre-established, transistor M2 is turned on, there is a bias voltage at the node VD, and the startup branch injects current into the bases of transistors Q3 and Q4 through transistor Q2. Among them, the node VSTART is the third end of transistor Q0, and the node VD is the third end of transistor M3.

[0042] Furthermore, based on zero shutdown current, the reliability of the startup unit 11 mainly depends on the injection characteristics of transistor Q2 and the clamping functions of transistors Q0 and Q1. In order to make the voltage of the node VSTART approximately equal to the voltage of the first end V4 of the second resistor network 122, the resistance values of resistors R1 and R3 are approximately equal. After the driving signal EN is pulled up, the voltage of the node VSTART is approximately 2V BE +IQ1 *The base voltages of R1, transistor Q3, and transistor Q4 are V BE +I Q3 *R1. At this time, the emitters of transistor Q3 and transistor Q4 are in the forward-biased state, and the gate voltages of transistor M5 and transistor M6 are established accordingly. Therefore, the gates of transistor M7 and transistor M8 are pulled low, and the currents in the two core branches of transistor Q3 and transistor Q4 start to be established. At this time, the current increases from zero. The emitter area ratio of Q3 and Q4 is 1:8, and the width-to-length ratios of transistor M7 and transistor M8 are the same. The currents in the two core branches enter the positive feedback state, and the low-temperature-drift reference circuit starts to start reliably. After the current gradually increases, resistor R2 causes the reference core unit 12 to enter the negative feedback state, and the reference voltage V BG is stably established. Among them, V BE is the base-emitter voltage of the transistor, and I Q1 is the emitter current of transistor Q1, and I Q3 is the emitter current of transistor Q3.

[0043] After the reference voltage V BG is stably established, the current flowing through transistor M12 is the same as the currents flowing through transistor M7 and transistor M8. Transistor Q5 realizes the reverse amplification function of the emitter currents of transistor Q3 and transistor Q4; transistor M13 realizes the transmission of the base current of transistor Q5 and injects it into the bases of transistor Q3 and transistor Q4 of the reference core unit 12, realizing the current compensation characteristic. Compared with the traditional reference circuit, this method eliminates the precision error brought by the base current to the reference voltage. In the temperature range of -55°C to 150°C, the amplification factor β of the transistor is different, and the reverse amplification function of the base current absorption unit 13 can follow the change of the ambient temperature.

[0044] Furthermore, Figure 2The circuit schematic diagram of a specific embodiment of the first resistor network 121 is shown. Among them, the first resistor network 121 is a T-shaped symmetric distributed resistor network, including resistor R31, resistor R32, resistor R33, resistor R34, resistor R35, resistor R36, and resistor R37. The first end of resistor R31 is the first end V1 of the first resistor network 121. The second end of resistor R31 is connected to the first end of resistor R32. The second end of resistor R32 is the fourth end V8 of the first resistor network 121. The first end of resistor R33 is connected to the first end of 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 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. The second end of resistor R37 is the third end V3 of the first resistor network 121. Among them, 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.

[0045] More specifically, resistors R32, R33, R35, R36, and R37 are positive temperature coefficient resistors.

[0046] More specifically, the types of resistors R32, R33, R35, R36, and R37 can be the same.

[0047] More specifically, resistors R31 and R34 are negative temperature coefficient resistors.

[0048] More specifically, the types of resistors R31 and R34 can be the same.

[0049] More specifically, the resistance values of the resistors in the first resistor network 121 are symmetrically equal respectively, that is, the resistance value of resistor R31 is equal to that of resistor R34, the resistance value of resistor R32 is equal to that of resistor R35, and the resistance value of resistor R33 is equal to that of resistor R36.

[0050] More specifically, the resistance value of resistor R37 is equal to that of resistor R3.

[0051] Optionally, resistor R37 can be a controllable resistor for generating a positive temperature coefficient voltage.

[0052] Furthermore, Figure 3 The circuit schematic diagram of a specific embodiment of the second resistor network 122 is shown, as Figure 3As shown, the second resistor network 122 includes resistor R41, resistor R42, resistor R43, and resistor R44. The first end of resistor R42 is the first end V4 of the second resistor network 122. The second end of resistor R42 is connected to the first ends of resistor R41, resistor R43, and resistor R44. The second end of resistor R44 is the second end V5 of the second resistor network 122. The second end of resistor R43 is the third end V6 of the second resistor network 122. The second end of resistor R41 is the fourth end V7 of the second resistor network 122. Among them, 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.

[0053] More specifically, the equivalent resistances seen from the first end V1 and the second end V2 of the first resistor network 121 to the fourth end V8 are equal. Using single-sided circuit analysis and setting resistor R37 to zero, the equivalent resistance R eq of seeing the fourth end V8 from the first end V1 and the second end V2 of the first resistor network 121 is derived. .

[0054] More specifically, in this application, based on the principle of first-order linear compensation, using the base-emitter voltage V BE of a triode and the change amount ΔV BE in the base-emitter voltage of the triode caused by temperature, and the principle of superposition, the compensation of the temperature coefficient is realized. The output waveform of the reference voltage V BG is approximately a quadratic parabola. Among them, ΔV BE is the change amount of the difference in the base-emitter voltage of the triode caused by temperature.

[0055] In the traditional Brokaw reference circuit, the first end V1, the second end V2, and the third end V3 of the first resistor network 121 are short-circuited, and the first end V4 and the second end V5 of the second resistor network 122 are short-circuited. Thus, the expression of the traditional reference voltage V BG is: .

[0056] Furthermore, combining Figure 1 with the first resistor network 121 in BG , the expression of the reference voltage V in this application is: Among them, the sum of the first two terms in the above formula 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 the triode Q3, the triode Q4, and the resistor R2.

[0057] Furthermore, the expressions of the resistor R32 and the resistor R33 are as follows: , wherein, and are the first-order temperature coefficients of the resistor R32 and the resistor R31 respectively, R 32,0 is the resistance value of the resistor R32 at the initial temperature T0, R 31,0 is the resistance value of the resistor R31 at the initial temperature T0, and T is the current temperature.

[0058] More specifically, the equivalent resistance R eq seen from the first end V1 of the first resistor network 121 and the second end V2 of the first resistor network 121 to the fourth end V8 can be simplified as follows: .

[0059] Therefore, the expression of the third positive temperature coefficient offset term introduced by the first resistor network 121 is: .

[0060] Furthermore, the above formula can be understood as that on the basis of the quadratic parabola curve, the first-order linear term is adjusted, and the reference voltage V BG always has the characteristic of a quadratic function curve, but compared with the traditional reference voltage V BG , the introduction of the third positive temperature coefficient offset term makes the relative zero-temperature point of the reference voltage V BG shifted.

[0061] Furthermore, on the basis of the zero-temperature point offset of the second resistor network 122, a secondary compensation is performed, a constant term is introduced, and the low-temperature drift characteristic of the reference circuit of the present application is realized. As Figure 1 and Figure 3 shown, the first end of the resistor R42 is connected to the base of the triode Q3, the second end of the resistor R44 is connected to the base of the triode Q4, the second end of the resistor R43 is connected to the first end of the transistor M15, and the second end of the resistor R41 is connected to the first end of the transistor M11. Among them, the current flowing through the resistor R42 and the resistor R44 is the base compensation current.

[0062] Furthermore, the collector current of the triode Q3 in the reference core unit 12 is , the transistor M5 operates in the saturation region, and the copy ratios of the transistors M7 and M12 are 1:1. Therefore, the collector current of the triode Q5 is . To ensure that the triode Q5 operates in the amplification region, the triode Q7 provides a bias voltage for the triodes Q5 and Q6. The base currents of the triodes Q5 and Q6 are both , and the base current of the triode Q7 can be approximately ignored. Therefore, the channel current of the transistor M13 is , and this current is twice the base currents of the triodes Q3 and Q4. Assuming that the current copy ratio from the transistor M13 to the transistor M11 is 1:N, through the current mirror composed of the transistors M13, M10, M14, and M15, where the current copy ratio from the transistor M13 to the transistor M15 is 1:K.

[0063] To achieve the base current compensation of the triodes Q3 and Q4 and simultaneously reduce the temperature drift coefficient, the selection of the parameters N and K needs to compensate for the third positive temperature coefficient offset term of the first resistor network 121.

[0064] Among them, the collector current of the triode Q3 is: In the second resistor network 122, the first terminal V4 is the reference voltage, and the voltage expression from the fourth terminal V7 to the first terminal V4 or the second terminal V5 is In the above formula , where M represents the direct compensation amount 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. It can be deduced that the expression of the reference voltage V BG is Among them, the sum of the first two terms in the above formula is the bandgap reference voltage, which is linearly superimposed by the change amount of the difference between the base-emitter voltages of the positive temperature coefficient triodes with temperature and the base-emitter voltage of the negative temperature coefficient triode ; the third term, that is, the third positive temperature coefficient offset term, is 's low-order compensation term; the fourth term is 's high-order compensation term, where the negative temperature coefficient accounts for a relatively large proportion. By adjusting the resistance values of the resistors R31 and R32, low-order compensation can be achieved, and by adjusting the values of M, N, the resistors R41, and the resistors R42, high-order compensation can be achieved, so that under the condition of temperature change, the sum of the above terms, that is, the reference voltage V BGRemain unchanged or change very little, so as to achieve low temperature drift.

[0065] Therefore, the low-temperature-drift reference circuit of the present application is based on the traditional Brokaw structure, combines the base current compensation idea, adopts a T-type resistor network, and based on the principle of Taylor expansion, for New reference voltage expressions are obtained by transformation at different temperature points. Depending on the positive temperature coefficient offset term to compensate the negative temperature coefficient voltage, the temperature drift characteristic of the reference can be further improved, so as to achieve low temperature drift.

[0066] Figure 4 It is a circuit schematic diagram of the second specific embodiment of a low-temperature-drift reference circuit of the present invention. As 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 and third ends of the transistor M21 through the resistor R20. The second end of the transistor M21 is connected to the first and third ends of the triode Q20. The second end of the triode Q20 is connected to the first and third ends 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 second end of the transistor M25. The first end of the transistor M25 is connected to the first and third ends 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 and third ends of the triode Q22. The second end of the triode Q22 is grounded to GNDA. The second end of the transistor M24 is the 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 first end of the transistor M26 is connected to the third end of the transistor M26 and the first end of the transistor M28 through the resistor R21. The third end of the transistor M28 is connected to the third end of the transistor M27. The second end of the transistor M28 is connected to the first end of the triode Q23. The third end of the triode Q23 is connected to the third end of the transistor Q22. The second end of the triode Q23 is grounded to GNDA through the resistor R22. The second end of the transistor M0 is connected to the voltage VDDA. The third end of the transistor M0 is connected to the third end of the transistor M24. The first end of the transistor M0 is connected to the first end of the transistor M2. 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 second end of the transistor M2. 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 grounded to GNDA through the 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 grounded to 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 grounded to GNDA. Among them, the third end of the transistor M2 is connected to the drive signal EN. The third ends of the transistor M4 and the transistor M17 are connected to the drive signal ENB. The drive signal EN and the drive signal ENB are opposite.

[0067] Optionally, the transistors M2 to M17 can be MOSFETs; the first end of each transistor is its drain, the second end of each transistor is its source, and the third end of each transistor is its gate.

[0068] More specifically, transistors M1, M7, M8, M9, M10, M11, M12, and M13 are N-type MOSFETs.

[0069] More specifically, transistors M2, M3, M4, M5, M6, M14, M15, M16, and M17 are P-type MOSFETs. Optionally, transistors M0, M21 to M28 can be MOSFETs; the first end of each transistor is its drain, the second end of each transistor is its source, and the third end of each transistor is its gate.

[0070] More specifically, transistors M0, M23, M24, M25, and M26 are N-type MOSFETs.

[0071] More specifically, transistors M21, M22, M27, and M28 are P-type MOSFETs.

[0072] Optionally, transistors Q20 to Q23 are NPN-type transistors, and the current amplification factor of each is β.

[0073] 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.

[0074] In Figure 4 In a specific embodiment, resistor R20, transistor M21, transistors Q20 and Q21 form a startup branch; transistors Q22 and Q23 form a 1:8 current definition tube; resistor R22 is used to define the current of the two bias branches where transistors Q22 and Q23 are located; transistors M27 and M28 form a Cascode structure; transistors M23, M24, M25, and M26 form a low-voltage Cascode structure for copying current; resistor R21 provides a bias voltage for transistors M23 to M26.

[0075] During startup, the startup branch is established in advance, where the gate voltage of transistor M21 is defined as a pre-startup voltage, 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 the voltage VDDA is greater than the pre-start voltage, there is current in the start-up branch, and transistor M22 operates in the saturation region, injecting current into two bias branches. At this time, the bias branch current is very small, and it enters the positive feedback loop.

[0076] During the establishment of the two bias currents, the gate voltage of transistor M22 approximately remains unchanged, and the expression is 2V BE +V GS21 ; transistor M27 approximately operates 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 ,wherein, 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. Therefore, when the voltage VDDA is greater than the pre-start voltage, the two bias currents start to be established. During the process of the current increasing continuously, the current of transistor M22 gradually decreases, and transistor M22 exits the saturation region, and the current gradually decreases to zero. The gate-source voltage V GS22 =V BE < the threshold voltage V TH ,transistor M22 turns off. After transistor M22 turns off, the drain-source current I DS22 =0, and the branch for injecting current is in a completely off state.

[0077] Among them, the gate of transistor M0 is connected to the gates of transistors M23 and M24 to form a linear current mirror, copying the two bias currents. After the supply voltage is established, for the start-up branch, 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 starts 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 with Figure 1 in the specific embodiment, Figure 4 in the specific embodiment uses transistor M0 to replace resistor R0 to realize the injection of the start-up current, which can further realize the highly reliable start-up process of the circuit.

[0078] For Figure 4The startup unit 21 therein. Within different supply voltage ranges, resistor R20 mainly determines the current of the startup branch. According to the exponential relationship between the base-emitter current I BE of the triode and the base-emitter voltage V BE , within the microampere-level current range, the voltage V BE changes very little and has no impact on the startup of the chip. Therefore, the problem of highly reliable startup of the chip within different supply voltage ranges is solved, and the circuit design idea is simplified. Compared with the startup unit in Figure 1 , the startup unit in Figure 4 can meet the requirements of highly reliable startup under high and low voltage conditions.

[0079] Furthermore, Figure 4 the reference core unit 22 in Figure 1 has the same structure and function as the reference core unit 12 in

[0080] , and will not be elaborated here. Furthermore, Figure 4 the base current absorption unit 23 in Figure 1 has the same structure and function as the base current absorption unit 13 in

[0081] , and will not be elaborated here. Furthermore, Figure 4 the first resistor network 221 in Figure 1 has the same structure and function as the first resistor network 121 in

[0082] , and will not be elaborated here. Furthermore, Figure 4 the second resistor network 222 in Figure 1 has the same structure and function as the second resistor network 122 in

[0083] , and will not be elaborated here. In summary, the low-temperature drift reference circuit provided by this application is based on the traditional Brokaw structure, combines the base current compensation idea, adopts a T-shaped resistor network, relies on the positive temperature coefficient voltage expansion term to compensate the negative temperature coefficient voltage, and can obtain a reference voltage with low temperature drift; by changing the resistor type and resistance value of the resistor network and the ratio relationship of the current mirror, the magnitude of the reference voltage can be adjusted. In addition, the circuit of the present invention can be implemented by using a conventional BCD process. Within the range of -55°C to 150°C, a reference voltage with a small temperature drift coefficient can be obtained, which can meet the requirements of the reference voltage required in the analog chip, improve the voltage accuracy and temperature drift coefficient of the chip; in addition, a very small chip size (DIE SIZE) can also be achieved, saving the process cost; it is applicable to both high-voltage and low-voltage occasions.

[0084] Figure 5 is the simulation waveform diagram of the traditional Brokaw bandgap reference circuit. Within the range of -55°C - 150°C, the temperature drift coefficient can reach 25 ppm; Figure 6This is the simulation waveform diagram of the low-temperature drift reference circuit of the present application, and the temperature drift coefficient can be improved to about 16 ppm.

[0085] Figure 7 This is the simulation waveform diagram of the low-temperature drift reference circuit of the present application when the drive signal EN changes from low to high. As can be seen from the figure, when the drive signal EN is pulled low, the startup branch is reliably turned off, and the current I of the low-temperature drift reference circuit BG is zero, and the power consumption of the low-temperature drift reference circuit of the present application is zero; when the drive 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 BG is 28.49 μA.

[0086] Figure 8 are the waveforms of the reference voltage V BG at different temperatures. In different temperature ranges, the minimum value of the reference voltage V BG after stabilization is approximately between 2.00 V and 2.20 V, which can meet most application scenarios.

[0087] Although the present invention has been disclosed as above by way of examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the appended patent application.

Claims

1. A low-temperature drift reference circuit, characterized in that, It includes 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; 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 a 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 through the 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. The third end of the sixth transistor is connected to the first end of the fourth triode. The second end of the fourth triode 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 triode and the second end of the second triode. The second end of the second resistor network is connected to the third end of the fourth triode. 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. The second end of the sixteenth transistor is grounded.

2. The low-temperature drift reference circuit according to claim 1, wherein 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. 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. 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. 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. 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. The second end of the thirty - seventh resistor is the third end of the first resistor network.

3. The low-temperature drift reference circuit according to claim 2, wherein 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.

4. The low-temperature drift reference circuit according to claim 3, wherein The starting unit includes a plurality of resistors, a plurality of transistors, and a plurality of triodes. The first voltage is connected to the first end of the second transistor through the zero 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 zero triode. The third end of the third transistor is connected to the first end of the first transistor. The second end of the zero 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 zero 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 zero triode is connected to the first end of the fourth transistor. The second end of the fourth transistor is grounded.

5. The low-temperature drift reference circuit according to claim 4, wherein The starting unit includes a plurality of resistors, a plurality of transistors, and a plurality of triodes. The first voltage is connected to the first and third ends of the twenty-first transistor through the twentieth resistor. The second end of the twenty-first transistor is connected to the first and third ends of the twenty-third triode. The second end of the twenty-third triode is connected to the first and third ends 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 and third ends 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 and third ends 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 triode. The third end of the twenty-third triode is connected to the third end of the twenty-second transistor. The second end of the twenty-third triode is grounded through the twenty-second resistor. The second end of the zero-th transistor is connected to the first voltage. The third end of the zero-th transistor is connected to the third end of the twenty-fourth transistor. The first end of the zero-th transistor is connected to the first end of the second transistor. 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 and third ends of the zero-th triode. The third end of the third transistor is connected to the second end of the second transistor. The second end of the zero-th triode is connected to the first and third ends of the first triode. The second end of the first triode is grounded through the first resistor. The third end of the zero-th 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 zero-th triode is connected to the first end of the fourth transistor. The second end of the fourth transistor is grounded.

6. The low-temperature drift reference circuit according to claim 4 or 5, characterized in that, The base current absorption unit includes a plurality of resistors, a plurality of transistors, and a plurality of 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 third ends of 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.

7. The low-temperature drift reference circuit according to claim 6, wherein Reference voltage V BG is expressed as Among them, V BE is the base-emitter voltage of the triode, ΔV BE is the change in the base-emitter voltage of the triode due to temperature, R3 is the resistance value of the third resistor, R2 is the resistance value of the second resistor, R eq is the equivalent resistance, β is the current amplification factor of the triode, 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.

8. The low-temperature-drift reference circuit according to claim 3, wherein 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.

9. The low-temperature drift reference circuit according to claim 3, wherein The thirty-seventh resistor is a controllable resistor.

10. For a low-temperature drift reference circuit as described in claim 3, the resistance value of the thirty-seventh resistor is equal to that of the third resistor.

Images