A low temperature drift buried zener reference circuit with high order temperature compensation

Abstract

The application relates to the field of integrated circuit design, in particular to a low-temperature-drift buried Zener reference circuit with high-order temperature compensation, which comprises a buried Zener reference core, a bias circuit, a starting circuit, an error amplifier, a feedback resistance network and a power tube, and a temperature compensation structure is added in the error amplifier; the temperature compensation structure is added in the circuit to obtain a more optimal reference voltage temperature characteristic curve, so that the temperature coefficient of the output reference voltage is smaller, and the output precision is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuit design, in particular to a low temperature drift buried zener reference circuit with high order temperature compensation. BACKGROUND

[0002] The reference voltage source is an indispensable module in the circuits such as analog-to-digital converter, digital-to-analog converter, linear voltage regulator and switching voltage regulator, temperature sensor, rechargeable battery protection chip, etc. Any deviation or noise in the numerical value of the reference voltage can directly affect the accuracy and performance of the whole system. In particular, the temperature change has a great influence on the reference voltage. In order to obtain a high-precision reference voltage source, the circuit needs to be temperature compensated.

[0003] With the development of technology, there is an increasing demand for high-precision and high-stability reference sources. Buried zener reference is a type of reference with good long-term stability. The traditional zener reference circuit generally only uses a triode for first-order compensation, and the output reference voltage has low precision and large temperature coefficient, which cannot meet the demand of high-performance circuits. SUMMARY

[0004] In order to reduce the temperature coefficient of the reference voltage and obtain a high-precision and low-temperature drift zener reference circuit, the present application provides a low temperature drift buried zener reference circuit with high order temperature compensation. The gate of the first N-type PN junction field effect transistor is connected to ground, the source thereof is connected together with the emitter of the first N-type triode, the collector of the fifth N-type triode, the collector of the sixth N-type triode, the emitter of the second N-type triode, the collector of the eleventh N-type triode, the emitter of the eighth P-type triode, the emitter of the ninth P-type triode, the collector of the seventh N-type triode, the emitter of the fourth N-type triode, and one end of the sixth resistor and the negative electrode of the diode to form a circuit output terminal, and the drain thereof is connected together with the collector and base of the first N-type triode, the collector and base of the first P-type triode, the base of the second P-type triode, and the base of the third P-type triode.

[0005] The base of the first N-type triode is connected together with the base and collector of the second N-type triode and the collector of the second P-type triode.

[0006] The base of the fifth N-type triode is connected together with one end of the third resistor, the negative electrode of the zener tube, and the collector of the eighth P-type triode, the other end of the third resistor is connected together with one end of the fourth resistor and one end of the fifth resistor, the other end of the fourth resistor is connected together with the base of the sixth N-type triode and the emitter of the seventh N-type triode, the other end of the fifth resistor is connected together with the collector and base of the fourteenth N-type triode and the base of the thirteenth N-type triode, the emitter of the fifth N-type triode is connected together with the emitter of the fourth P-type triode and the emitter of the fifth P-type triode.

[0007] The emitter of the sixth N-type triode is connected together with the emitter of the sixth P-type triode and the emitter of the seventh P-type triode;

[0008] The emitter of the first, second and third P-type triodes is connected together with the collector of the fourth N-type triode;

[0009] The base of the eleventh N-type triode is connected together with the collector of the sixth P-type triode, the collector of the ninth N-type triode and one end of the second resistor; the emitter of the eleventh N-type triode is connected together with the base of the twelfth N-type triode and the collector of the fifteenth N-type triode;

[0010] The base of the eighth P-type triode is connected together with the base and collector of the ninth P-type triode, the collector of the sixteenth N-type triode and the collector of the thirteenth N-type triode;

[0011] The base of the seventh N-type triode is connected together with the other end of the sixth resistor and one end of the seventh resistor; the other end of the seventh resistor is connected together with the emitter of the seventeenth N-type triode, one end of the tenth resistor, the emitter of the sixteenth N-type triode, the anode of the Zener tube, the emitter of the fifteenth N-type triode, the emitter of the tenth N-type triode, one end of the eighth resistor, one end of the ninth resistor and the emitter of the twelfth N-type triode and is connected to the ground terminal;

[0012] The base of the fourth N-type triode is connected together with the collector of the third P-type triode, the base and collector of the third N-type triode;

[0013] The emitter of the fourteenth N-type triode is connected together with the collector and base of the seventeenth N-type triode, the base of the sixteenth N-type triode and the base of the fifteenth N-type triode;

[0014] The emitter of the thirteenth N-type triode is connected together with the base of the tenth N-type triode and the other end of the tenth resistor;

[0015] The base of the sixth P-type triode is connected together with the base and collector of the seventh P-type triode, one end of the first resistor and the collector of the fifth P-type triode; the other end of the first resistor is connected together with the collector of the tenth N-type triode, the base of the fourth P-type triode and the base of the fifth P-type triode;

[0016] The base of the ninth N-type triode is connected together with the base and collector of the eighth N-type triode and the collector of the fourth P-type triode; the emitter of the ninth N-type triode is connected together with the other end of the ninth resistor;

[0017] The collector of the twelfth N-type triode is connected with the emitter of the third N-type triode, one end of the capacitor and the anode of the diode, and the other end of the capacitor is connected with the other end of the second resistor;

[0018] The other end of the eighth resistor is connected with the emitter of the eighth N-type triode.

[0019] Further, the negative electrode of the Zener tube is connected with one end of the twelfth resistor, and the other end of the twelfth resistor is connected with one end of the third resistor and the base of the fifth N-type triode.

[0020] Further, the emitter of the seventh N-type triode is connected with one end of the eleventh resistor, and the other end of the eleventh resistor is connected with the other end of the fourth resistor and the base of the sixth N-type triode.

[0021] Further, the area ratio of the emitter of the sixth N-type triode to the emitter of the fifth N-type triode is 4:1.

[0022] Further, the temperature coefficient of the first resistor is controlled by adjusting the type of the first resistor.

[0023] Further, the breakdown voltage of the Zener tube is positive temperature coefficient, and the base-emitter voltage of the N-type triode is negative temperature coefficient.

[0024] Further, the voltage difference between the positive input end and the negative input end of the first amplifier is controlled by adjusting the resistance values of the eighth resistor and the ninth resistor.

[0025] The general error amplifier is used to keep the voltages of two input ends approximately equal, that is, V P =V N =V Z1 , at this time, the reference nuclear voltage is V REF =V P +V BEN7 =V Z1 +V BEN7 , wherein the breakdown voltage V Z of the Zener tube is positive temperature coefficient, and the base-emitter voltage V BE of the N-type triode is negative temperature coefficient, so that the reference voltage of first-order temperature compensation can be obtained; the voltage difference between V P and V N is formed, a voltage term with high-order coefficient of temperature is introduced, and the high-order term can be adjusted, the term is introduced into the reference voltage, and the reference voltage of high-order temperature compensation can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Structure diagram of a low temperature drift buried zener reference circuit with high order temperature compensation according to the present application;

[0027] Figure 2 Structure diagram of a first amplifier in a low temperature drift buried zener reference circuit with high order temperature compensation according to the present application;

[0028] Figure 3 Output voltage simulation result of a zener reference circuit according to the present application;

[0029] Figure 4 Output voltage simulation result of a prior art zener reference circuit;

[0030] Figure 5 Structure diagram of an optimal implementation of a low temperature drift buried zener reference circuit with high order temperature compensation according to the present application;

[0031] Wherein, J1, first N-type PN junction field effect transistor; N1, first N-type triode; N2, second N-type triode; N3, third N-type triode; N4, fourth N-type triode; N5, fifth N-type triode; N6, sixth N-type triode; N7, seventh N-type triode; N8, eighth N-type triode; N9, ninth N-type triode; N10, tenth N-type triode; N11, eleventh N-type triode; N12, twelfth N-type triode; N13, thirteenth N-type triode; N14, fourteenth N-type triode; N15, fifteenth N-type triode; N16, sixteenth N-type triode; N17, seventeenth N-type triode; P1, first P-type triode; P2, second P-type triode; P3, third P-type triode; P4, fourth P-type triode; P5, fifth N-type triode; P6, sixth P-type triode; P7, seventh P-type triode; P8, eighth P-type triode; P9, ninth P-type triode; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; R8, eighth resistor; R9, ninth resistor; R10, tenth resistor; R11, eleventh resistor; R12, twelfth resistor; D1, diode; Z1, zener diode; C1, capacitor; A1, first amplifier; A2, second amplifier; A3, third amplifier. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0033] This invention proposes a low-temperature drift buried Zener reference circuit with high-order temperature compensation. The circuit is characterized in that the gate of the first N-type PN junction field-effect transistor J1 is grounded, and its source is connected to the emitter of the first N-type transistor N1, the collector of the fifth N-type transistor N5, the collector of the sixth N-type transistor N6, the emitter of the second N-type transistor N2, and the eleventh N-type transistor N... 11 The collector of the first N-type transistor, the emitter of the eighth P-type transistor P8, the emitter of the ninth P-type transistor P9, the collector of the seventh N-type transistor N7, the emitter of the fourth N-type transistor N4, one end of the sixth resistor R6, and the negative terminal of diode D1 are connected together as the circuit output terminal. Its drain is connected together with the collector of the first N-type transistor N1, the collector and base of the first P-type transistor P1, the base of the second P-type transistor P2, and the base of the third P-type transistor P3.

[0034] The base of the first N-type transistor is connected to the base and collector of the second N-type transistor and the collector of the second P-type transistor.

[0035] The base of the fifth N-type transistor is connected to one end of the third resistor R3, the negative terminal of the Zener transistor Z1, and the collector of the eighth P-type transistor. The other end of the third resistor is connected to one end of the fourth resistor R4 and one end of the fifth resistor. The other end of the fourth resistor is connected to the base of the sixth N-type transistor and the emitter of the seventh N-type transistor. The other end of the fifth resistor R5 is connected to the N-type transistor of the fourteenth N-type transistor. 14 The collector and base of the thirteenth N-type transistor N 13 The bases of the five N-type transistors are connected together; the emitter of the fifth N-type transistor is connected to the emitter of the fourth P-type transistor P4 and the emitter of the fifth P-type transistor P5.

[0036] The emitter of the sixth N-type transistor is connected to the emitter of the sixth P-type transistor P6 and the emitter of the seventh P-type transistor P7.

[0037] The emitters of the first, second, and third P-type transistors are connected to the collector of the fourth N-type transistor.

[0038] The base of the eleventh N-type transistor is connected to the collector of the sixth P-type transistor, the collector of the ninth N-type transistor N9, and one end of the second resistor R2; the emitter of the eleventh N-type transistor is connected to the emitter of the twelfth N-type transistor N9. 12 The base of the fifteenth N-type transistor N 15 The collectors are connected together;

[0039] The base of the eighth P-type transistor and the base and collector of the ninth P-type transistor, and the N-type transistor of the sixteenth N-type transistor.16 The collector of the transistor and the collector of the thirteenth N-type transistor are connected together;

[0040] The base of the seventh N-type transistor is connected to the other end of the sixth resistor and one end of the seventh resistor R7. The other end of the seventh resistor is connected to the N-type transistor of the seventeenth N-type transistor. 17 The emitter of the 10th resistor, one end of the 16th N-type transistor, the positive terminal of the Zener transistor, the emitter of the 15th N-type transistor, and the N-type transistor of the 10th N-type transistor. 10 The emitter of the first transistor, one end of the eighth resistor R8, one end of the ninth resistor R9, and the emitter of the twelfth N-type transistor are connected together and connected to the ground terminal.

[0041] The base of the fourth N-type transistor is connected to the collector of the third P-type transistor, and the base and collector of the third N-type transistor N3.

[0042] The emitter of the fourteenth N-type transistor is connected to the collector and base of the seventeenth N-type transistor, the base of the sixteenth N-type transistor, and the base of the fifteenth N-type transistor.

[0043] The emitter of the thirteenth N-type transistor is connected to the base of the tenth N-type transistor, and the tenth resistor R. 10 The other end is connected together;

[0044] The base of the sixth P-type transistor is connected to the base and collector of the seventh P-type transistor, one end of the first resistor R1, and the collector of the fifth P-type transistor. The other end of the first resistor is connected to the collector of the tenth N-type transistor, the base of the fourth P-type transistor, and the base of the fifth P-type transistor.

[0045] The base of the ninth N-type transistor is connected to the base and collector of the eighth N-type transistor N8 and the collector of the fourth P-type transistor; the emitter of the ninth N-type transistor is connected to the other end of the ninth resistor.

[0046] The collector of the twelfth N-type transistor is connected to the emitter of the third N-type transistor, one end of capacitor C1, and the positive terminal of the diode. The other end of the capacitor is connected to the other end of the second resistor.

[0047] The other end of the eighth resistor is connected to the emitter of the eighth N-type transistor.

[0048] This embodiment also provides an improved solution, wherein a twelfth resistor R is provided between the negative terminal of the Zener transistor and one end of the third resistor, and between the base of the fifth N-type transistor. 12That is, the negative terminal of the Zener transistor is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to one end of the third resistor and the base of the fifth N-type transistor; an eleventh resistor R is placed between the emitter of the seventh N-type transistor and the other end of the fourth resistor, and the base of the sixth N-type transistor. 11 That is, the emitter of the seventh N-type transistor is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected to the other end of the fourth resistor and the base of the sixth N-type transistor.

[0049] This invention designs a buried Zener reference circuit, which includes a buried Zener reference core, a bias circuit, a startup circuit, an error amplifier, a feedback resistor network, a power transistor, etc. The reference circuit of this invention incorporates a temperature compensation structure in the error amplifier, as shown in the attached diagram. Figure 1 As shown, the temperature compensation circuit consists of an amplifier (hereinafter referred to as the first amplifier A1) and two resistors, a third resistor R3 and a fourth resistor R4. The inputs of the first amplifier A1 are connected to one end of the third resistor R3 and the fourth resistor R4, respectively. The output of the first amplifier A1 is connected to the eleventh N-type transistor N. 11 The base is connected.

[0050] The specific circuit diagram of this invention is shown in the attached figure. Figure 1 As shown, a buried Zener reference circuit with high-order temperature compensation is disclosed. This circuit includes a buried Zener reference core, a bias circuit, a startup circuit, an error amplifier, a feedback resistor network, and power transistors. The reference core consists of a Zener transistor Z1 and a seventh N-type transistor N7. The error amplifier consists of a first amplifier A1, a second amplifier A2, and a third amplifier A3. The high-order temperature compensation structure consists of the first amplifier A1, a third resistor R3, and a fourth resistor R4.

[0051] After incorporating a high-order temperature compensation structure, the reference core voltage is:

[0052]

[0053] in, The reference core voltage; This is the breakdown voltage of the first buried Zener diode; This represents the base-emitter voltage of the seventh N-type transistor; Thermoelectric voltage; This is the collector current of the sixth N-type transistor; This is the collector current of the fifth N-type transistor; This is the collector current of the fifth P-type transistor; This is the collector current of the seventh P-type transistor; This is the resistance value of the first resistor.

[0054] The output reference voltage is:

[0055]

[0056] in, This is the resistance value of the sixth resistor; This is the resistance value of the seventh resistor.

[0057] The above equation shows that by adding the designed first amplifier A1, a high-order temperature-compensated reference voltage can be obtained without significantly increasing the circuit structure. Furthermore, the high-order temperature coefficient can be adjusted by changing the values ​​of the eighth resistor R8 and the ninth resistor R9, thereby obtaining a lower reference voltage temperature coefficient. The temperature characteristic curve of the reference voltage obtained through simulation is shown in the attached figure. Figure 3 Appendix Figure 4 As shown, attached Figure 4 The simulation results for a typical amplifier structure show that its reference voltage temperature characteristic curve is approximately a quadratic function, and its temperature coefficient across the entire temperature range is calculated to be 5.4 ppm / ℃. (See attached image.) Figure 3 The simulation results of the high-order temperature compensation structure designed in this invention show that its reference voltage temperature characteristic curve is approximately a cubic function with a temperature coefficient of 0.3 ppm / ℃ across the entire temperature range, and the temperature coefficient decreases by orders of magnitude across the entire temperature range.

[0058] The method for calculating the temperature coefficient across the entire temperature range is as follows:

[0059]

[0060] Where TC is the temperature coefficient; V MAX The maximum value of the reference voltage; V MIN The minimum value of the reference voltage; V AVE The average value of the reference voltage; T MAX T represents the maximum operating temperature. MIN This is the minimum operating temperature.

[0061] Based on the aforementioned embodiments, an eleventh resistor R is added. 11 12th resistor R 12 As attached Figure 5 As shown. Add an eleventh resistor R. 11 The twelfth resistor R 12 The formula for calculating the reference voltage is approximately as follows:

[0062]

[0063] in, This represents the base-emitter voltage of the fourteenth N-type transistor; This represents the base-emitter voltage of the seventeenth N-type transistor; This is the resistance value of the eleventh resistor; This is the resistance value of the twelfth resistor; This is the resistance value of the third resistor; This is the resistance value of the fifth resistor.

[0064] As can be seen from the above formula, The magnitude of the resistance is positively correlated with temperature; increasing the resistance of the eleventh resistor R... 11 The twelfth resistor R 12 Then, adjusting its size can change the temperature coefficient, thus allowing for a lower reference voltage temperature coefficient to be obtained by modifying the size of the resistor when there are deviations in the process.

[0065] This invention discloses a buried Zener reference circuit with high-order temperature compensation. By adding a temperature compensation structure to the circuit, a better quasi-voltage temperature characteristic curve is obtained, thereby making the output reference voltage temperature coefficient smaller and the output accuracy higher.

[0066] The general function of an error amplifier is to keep the voltages at its two input terminals approximately equal, i.e., V P =V N =V Z1 At this time, the reference core voltage is V. REF =V P +V BEN7 =V Z1 +V BEN7 The breakdown voltage of the Zener diode is V. Z With a positive temperature coefficient, the base-emitter voltage V of an N-type transistor is... BE Because it has a negative temperature coefficient, a first-order temperature-compensated reference voltage can be obtained. The first amplifier A1 of this invention is shown in the attached figure. Figure 2 As shown, the emitter area ratio of the sixth N-type transistor N6 and the fifth N-type transistor N5 is 4:1, at V P and V N A pressure difference is formed between them, that is:

[0067]

[0068] And because of V BE =V T ×ln(I C / I S ), I S6 =4I S5 I R1 ≈I CP5 +I CP7 Therefore, we can conclude that:

[0069]

[0070] In the above formula, I CP5 =I CP4 I CP7 =ICP6 I CN5 =I CP4 +I CP5 I CN6 =I CP6 +I CP7 , so I CP5 I CP7 I CN5 and I CN6 The value can be adjusted via the eighth resistor R8 and the ninth resistor R9, and V T I C Since both are temperature-related, a voltage term with a high-order coefficient relationship to temperature is introduced into the two input terminals of the first amplifier A1. This high-order term can be adjusted and introduced into the reference voltage to obtain a reference voltage with high-order temperature compensation.

[0071] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature drift buried Zener reference circuit with high-order temperature compensation, characterized in that, In this circuit, the gate of the first N-type PN junction field-effect transistor is grounded. Its source is connected to the emitter of the first N-type transistor, the collector of the fifth N-type transistor, the collector of the sixth N-type transistor, the emitter of the second N-type transistor, the collector of the eleventh N-type transistor, the emitter of the eighth P-type transistor, the emitter of the ninth P-type transistor, the collector of the seventh N-type transistor, the emitter of the fourth N-type transistor, one end of the sixth resistor, and the cathode of the diode as the circuit output terminal. Its drain is connected to the collector of the first N-type transistor, the collector and base of the first P-type transistor, the base of the second P-type transistor, and the base of the third P-type transistor. The base of the first N-type transistor is connected to the base and collector of the second N-type transistor and the collector of the second P-type transistor. The base of the fifth N-type transistor is connected to one end of the third resistor, the negative terminal of the Zener transistor, and the collector of the eighth P-type transistor. The other end of the third resistor is connected to one end of the fourth resistor and one end of the fifth resistor. The other end of the fourth resistor is connected to the base of the sixth N-type transistor and the emitter of the seventh N-type transistor. The other end of the fifth resistor is connected to the collector and base of the fourteenth N-type transistor and the base of the thirteenth N-type transistor. The emitter of the fifth N-type transistor is connected to the emitter of the fourth P-type transistor and the emitter of the fifth P-type transistor. The emitter of the sixth N-type transistor is connected to the emitter of the sixth P-type transistor and the emitter of the seventh P-type transistor. The emitters of the first, second, and third P-type transistors, and the collector of the fourth N-type transistor, and the power supply voltage V. IN Connected together; The base of the eleventh N-type transistor is connected to the collector of the sixth P-type transistor, the collector of the ninth N-type transistor, and one end of the second resistor; the emitter of the eleventh N-type transistor is connected to the base of the twelfth N-type transistor and the collector of the fifteenth N-type transistor. The base of the eighth P-type transistor is connected to the base and collector of the ninth P-type transistor, the collector of the sixteenth N-type transistor, and the collector of the thirteenth N-type transistor. The base of the seventh N-type transistor is connected to the other end of the sixth resistor and one end of the seventh resistor. The other end of the seventh resistor is connected to the emitter of the seventeenth N-type transistor, one end of the tenth resistor, the emitter of the sixteenth N-type transistor, the positive terminal of the Zener transistor, the emitter of the fifteenth N-type transistor, the emitter of the tenth N-type transistor, one end of the eighth resistor, one end of the ninth resistor, and the emitter of the twelfth N-type transistor, and is connected to the ground terminal. The base of the fourth N-type transistor is connected to the collector of the third P-type transistor, and the base and collector of the third N-type transistor are connected together. The emitter of the fourteenth N-type transistor is connected to the collector and base of the seventeenth N-type transistor, the base of the sixteenth N-type transistor, and the base of the fifteenth N-type transistor. The emitter of the thirteenth N-type transistor is connected to the base of the tenth N-type transistor and the other end of the tenth resistor. The base of the sixth P-type transistor is connected to the base and collector of the seventh P-type transistor, one end of the first resistor, and the collector of the fifth P-type transistor. The other end of the first resistor is connected to the collector of the tenth N-type transistor, the base of the fourth P-type transistor, and the base of the fifth P-type transistor. The base of the ninth N-type transistor is connected to the base and collector of the eighth N-type transistor and the collector of the fourth P-type transistor; the emitter of the ninth N-type transistor is connected to the other end of the ninth resistor. The collector of the twelfth N-type transistor is connected to the emitter of the third N-type transistor, one end of the capacitor, and the positive terminal of the diode. The other end of the capacitor is connected to the other end of the second resistor. The other end of the eighth resistor is connected to the emitter of the eighth N-type transistor.

2. The low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 1, characterized in that, A twelfth resistor is placed between the negative terminal of the Zener transistor, one end of the third resistor, and the base of the fifth N-type transistor. That is, the negative terminal of the Zener transistor is connected to one end of the twelfth resistor, and the other end of the twelfth resistor is connected to one end of the third resistor and the base of the fifth N-type transistor.

3. The low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 2, characterized in that, An eleventh resistor is provided between the emitter of the seventh N-type transistor and the other end of the fourth resistor, and the base of the sixth N-type transistor. That is, the emitter of the seventh N-type transistor is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected to the other end of the fourth resistor and the base of the sixth N-type transistor.

4. The low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 1, characterized in that, The emitter area ratio of the sixth N-type transistor to that of the fifth N-type transistor is 4:

1.

5. A low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 1, characterized in that, The temperature coefficient of the first resistor is controlled by adjusting the type of the first resistor.

6. The low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 1, characterized in that, Zener diodes have a positive temperature coefficient of breakdown voltage, while N-type transistors have a negative temperature coefficient of base-emitter voltage.

7. A low-temperature drift buried Zener reference circuit with high-order temperature compensation according to claim 1, characterized in that, The voltage difference between the positive and negative input terminals of the first amplifier is controlled by adjusting the resistance values ​​of the eighth and ninth resistors.

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