A bandgap reference circuit using segmented compensation technology to reduce temperature drift coefficient

Abstract

The present invention discloses a bandgap reference circuit that uses segmented compensation technology to reduce the temperature drift coefficient. The circuit includes four parts: a turn-on circuit, a first-order bandgap, a subthreshold positive temperature current, and a compensation circuit. The turn-on circuit is used to eliminate the degenerate bias point of the PTAT current generating circuit, allowing it to operate normally and stably. The first-order bandgap is used to perform first-order compensation on the output voltage, obtaining a voltage near zero temperature and generating a positive temperature current with a large slope. The subthreshold positive temperature current circuit is used to generate a positive temperature current with a slope smaller than that generated by the first-order bandgap circuit. The compensation circuit uses a subtraction circuit to process the two positive temperature currents, extracting the first-order compensated current at high and low temperatures, respectively, to obtain an output voltage with a lower temperature coefficient. The present invention achieves segmented compensation by using two positive temperature currents with different slopes.

Description

Technical Field

[0001] The present invention belongs to the technical field of bandgap reference circuits, and in particular relates to a bandgap reference circuit which reduces a temperature drift coefficient by utilizing a segmented compensation technology. Background Art

[0002] As one of the most critical components in analog integrated circuits, bandgap references are widely used in a variety of integrated circuit devices, including operational amplifiers, digital-to-analog converters, analog-to-digital converters, and filters. They are widely used in practical projects. High-performance analog circuits must be supported by high-quality, highly stable current and voltage bias circuits, whose performance directly affects the circuit's power consumption, power supply rejection ratio, open-loop gain, and temperature characteristics. Existing segmented compensation circuits often require two or more op amps to generate independent positive and negative temperature currents, which occupies a large area and increases design complexity. Therefore, further innovation and new solutions are needed.

[0003] Existing segmented compensation band gaps require two op amp clamps to obtain independent positive and negative temperature currents, which will cause the impact of offset voltage, increase power consumption and area; independent negative temperature currents that do not use op amps have stability issues and require frequency compensation.

[0004] like Figure 3 As shown, the existing case uses op amp OP1 to clamp points A and B to obtain a positive temperature current:

[0005]

[0006] I PT To utilize the positive temperature current generated by the operational amplifier OP1, ΔV BE The base-collector voltage difference of the two transistors is used for current mirroring through VBP9.

[0007] Then use op amp OP2 to clamp points B and C to obtain negative temperature current:

[0008]

[0009] V CT To utilize the negative temperature current generated by op amp 2, V BE It is the base-collector voltage of Q3 and is mirrored by VBP7.

[0010] The output voltage of the first-order compensation is:

[0011] V E =(I PT +I CT )×(R1+R2)

[0012] V E is the voltage after first-order compensation; IPT is the positive temperature current generated by operational amplifier 1; I CT It is the negative temperature current generated by operational amplifier 2.

[0013] The second-order compensation part is similar to the present invention, and uses a subtraction circuit to process independent positive temperature current and negative temperature current, extracting a part of the current in the low temperature section and the high temperature section respectively to reduce the temperature drift coefficient of the final output voltage.

[0014] This solution uses two op amps, which can lead to offset voltage, increased power consumption and area, and increased circuit design difficulty. Furthermore, this solution does not adopt a cascode structure, resulting in a low power supply rejection ratio. Summary of the Invention

[0015] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a bandgap reference circuit that uses segmented compensation technology to reduce the temperature drift coefficient, adopts a common source and common gate structure for clamping, saves area and power consumption, and improves the power supply rejection ratio; through a positive temperature current working in the subthreshold region, the slope of this current is smaller than the positive temperature current slope formed by using a transistor, and these two positive temperature currents are used to perform segmented compensation to reduce the temperature drift coefficient of the bandgap.

[0016] In order to achieve the above object, the technical solution adopted by the present invention is:

[0017] A bandgap reference circuit that uses segmented compensation technology to reduce temperature drift coefficient includes four parts: a turn-on circuit, a first-order bandgap, a subthreshold positive temperature current, and a compensation circuit.

[0018] The turn-on circuit is used to eliminate the degenerate bias point of the PTAT current generating circuit, allowing it to operate normally and stably;

[0019] The first-order band gap is used to perform first-order compensation on the output voltage, obtain a near-zero-temperature voltage, and generate a first positive temperature current;

[0020] The subthreshold positive temperature current circuit is used to generate a second positive temperature current, and the slope of the second positive temperature current is smaller than the slope of the first positive temperature current;

[0021] The compensation circuit processes two positive temperature currents using a subtraction circuit, extracts the first-order compensated currents at a high temperature stage and a low temperature stage respectively, thereby obtaining an output voltage with a lower temperature coefficient.

[0022] The start-up circuit includes MOS transistors M1 to M8, wherein the gates of M1 to M4 are connected together and connected to the drain of M4; the source of M1 is connected to the power supply, the drain is connected to the source of M2, the drain of M2 is connected to the source of M3, the drain of M3 is connected to the source of M4, the drain of M4 is connected to the gates of M1, M2, M3, M4, M6, and the drain of M5; the gate of M5 is connected to the bandgap output voltage V ref , the source is grounded; the source of M6 is grounded, and the drain is connected to the gate and drain of M7; the source of M7 is connected to the power supply, the gate is connected to the drain of M7, the drain of M6, and the gate of M8; the gate of M8 is connected to the gate of M7, the source is connected to the power supply, and the drain is connected to the gate voltage VBN3 of M19.

[0023] During the power-on process of the power supply voltage, the bias circuit composed of M1-M4 and M6 supplies power to the gate of the M8 tube. At the beginning of power-on, the M8 tube is turned on, and the potential of the VBN3 point is raised, so that the PTAT current generating circuit breaks away from the degenerate bias point and starts to work normally. When the output of the PTAT current generating circuit is normal, a near-zero temperature voltage Vref can be obtained to provide a gate voltage for the M5 tube, so that M5 starts to turn on. The gate voltage of the M6 ​​tube gradually decreases until it is turned off. At the same time, the gate voltage of the M7 and M8 tubes gradually increases until the tubes are turned off, ending the power-on process.

[0024] The first-order bandgap includes a positive temperature circuit consisting of MOS tubes M14-M21, resistors R4-R6, and transistors Q1 and Q2, wherein the gates of M14, M15, and M59 are connected and connected to the drain voltage of M16, and this point voltage is named VBP9, and the sources of these three MOS are all connected to the power supply; the gates of M16, M17, and M60 are connected together and connected to the drain voltage of M18, and this point voltage is named VBP10; the drain of M14 is connected to the source of M16, and the drain of M16 is connected to R4 and the gate voltage VBP9 of M14; the drain of M15 is connected to the source of M17, and the drain of M17 is connected to R5 and the gate voltage VBN3 of M19; R4 is connected Connected between VBP9 and VBP10, R5 is connected between VBN3 and VBN4; the drain of M18 is connected to VBP10, the gate is connected to VBN3, the source is connected to the drain of M20, the gate of M20 is indirectly connected to VBN4, the source is connected to R6, the drain of M19 is connected to VBN4, the gate is connected to VBN3, the source is connected to the drain of M21, the gate of M21 is connected to VBN4, the drain is connected to the emitter of transistor Q2, the other end of R6 is connected to the emitter of transistor Q1, the bases of Q1 and Q2 are connected and grounded, the collectors of Q1 and Q2 are also grounded, the source of M59 is connected to the power supply, the gate is connected to VBP9, the drain is connected to the source of M60, the gate of M60 is connected to VBO10, and the drain is connected to V ref , one end of R3 is connected to V ref, the other end is connected to R8, the other end of R8 is connected to the emitter of transistor Q3, and the base and collector of Q3 are connected and grounded.

[0025] The MOS tubes M14 to M17 form a set of cascode current mirrors to ensure that the currents in the two branches are the same. M18 to M21 form another set of cascode current mirrors. Since the currents in the two branches are the same, the VGS of M20 and M21 are the same. Since the gates of the two tubes are connected, the source voltage is also the same, replacing the virtual short function of the op amp, so that the source voltages of M20 and M21 are the same. The positive temperature current formula is:

[0026]

[0027] I PT1 is the positive temperature current generated by the first-order band gap, ΔV BE is the base-collector voltage difference between the two transistors, and R6 is the resistance of this branch;

[0028] The current has a positive temperature coefficient, and the resistor selected is the RPPLOYU resistor with a very small temperature drift coefficient (temperature drift can be ignored). Therefore, the voltage across the resistor also has a positive temperature coefficient, while the base-emitter voltage of the transistor has a negative temperature coefficient. Adding the two voltages can obtain a voltage with nearly zero temperature drift. The formula for the first-order compensation voltage is:

[0029] V E =I PT1 (R3+R8)+V BE3

[0030] V E is the voltage after first-order compensation; I PT1 is the positive temperature current generated by the first-order band gap; R3 and R8 are the two resistor values ​​on the output branch; V BE3 is the base-collector voltage of transistor Q3.

[0031] The subthreshold positive temperature current includes MOS tubes M22 to M27 and resistor R7, forming a positive temperature current, wherein the gates of M22 and M23 are connected to each other VBP7, and the sources of the two tubes are connected to the power supply, the drain of M22 tube is connected to VBP7 and the source of M24; the drain of M23 is connected to the source of M25, the gates of M24 and M25 are connected to each other VBP8, the drain of M24 is connected to VBP8 and the drain of M26, the drain of M25 is connected to the gate and source of M27, the gates of M26 and M27 are connected, the source of M265 is connected to R7, the other end of R7 is grounded, the gate and drain of M27 are connected, and the source is grounded.

[0032] The positive temperature current is:

[0033]

[0034] I PT2 The current generated by the subthreshold positive temperature current; ΔV GS is the gate-source voltage difference between the two MOSFETs M26 and M27; R7 is the resistance value of the branch resistor;

[0035] M26 and M27 work in the subthreshold region. The gate-source voltage difference formula of MOS working in the subthreshold region is as follows:

[0036]

[0037] ΔV GS is the gate-source voltage difference of MOS working in the subthreshold region; V th1 and V th2 are the threshold voltages of the two MOS tubes respectively; n is the subthreshold slope correction factor; is the thermovoltage, which has a positive temperature coefficient; and is the spaciousness ratio of the two MOS tubes;

[0038] According to the above formula, ΔV GS It has a positive temperature characteristic, so the current also has a positive temperature characteristic, and the temperature coefficient is smaller than the positive temperature characteristic of the transistor.

[0039] In the compensation circuit, the gate of M33 is connected to VBP9, the source is connected to the power supply, the drain is connected to the source of M34, the gate of M34 is connected to VBP10, the drain is connected to the drain and gate of M37, the gate of M37 is connected to the gate of M39, the drain of M37 is connected to the drain and gate of M38, the gate of M38 is connected to the gate of M40, the source of M38 is grounded, the source of M40 is grounded, the drain is connected to the source of M39, the drain of M39 is connected to M The drain of M36 is connected to the drain of M32, the gate of M36 is connected to VBP8, the source is connected to the drain of M35, the gate of M35 is connected to VBP7, and the source is connected to the power supply; the gate of M38 is connected to the gate of M31, the drains of M39, M32 and M36 are connected, the source of M32 is connected to the power supply, the source of M31 is connected to the power supply, the drain is connected to the drain and gate of M64, the gate of M64 is connected to the gate of M63, the source of M64 is grounded, the source of M63 is grounded, and the drain is connected to R8;

[0040] The gate of M41 is connected to VBP7, the source is connected to the power supply, the drain is connected to the source of M42, the gate of M42 is connected to VBP8, the drain is connected to the drain and gate of M45, the gate of M45 is connected to the gate of M47, the drain of M45 is connected to the drain and gate of M46, the gate of M46 is connected to the gate of M48, the source of M46 is grounded, the source of M48 is grounded, the drain is connected to the source of M47, the drain of M47 is connected to the drain of M44 and M2 The drain of M29 is connected to the gate of M30, the source of M44, M47 and M29 are connected, the source of M29 is connected to the power supply, the source of M30 is connected to the power supply, the drain is connected to the drain and gate of M62, the gate of M62 is connected to the gate of M61, the source of M62 is grounded, the source of M61 is grounded, and the drain is connected to R8.

[0041] Positive temperature current I generated by subthreshold MOS PT2 Mirrored to the branch where M41 and M42 are located through M23 and M25, generating the size bit A1I PT2 The positive temperature current generated by the first-order band gap is I PT1 Mirrored to the M43 M44 branch through M15 and M17, the size is A2I PT1 The positive temperature current is adjusted by adjusting the two coefficients, so that A1I PT2 >A2I PT1 At this time, M29 in the current subtraction circuit will be turned on. As the temperature increases, the difference between the two currents continues to decrease. Therefore, the current on M29 is a negative temperature current. If the current after the mirror image through M30, M61, and M62 is A3I M29 , then the magnitude of this compensation current is:

[0042] I COMP_CT =A3(A1I PT2 -A2I PT1 )

[0043] I COMP_CT is the magnitude of the compensation current in the low temperature stage; A3 is the ratio of the mirror current of the M62 tube and the M61 tube; A1 is the ratio of the mirror current of the M41 tube and the M23 tube; A2 is the ratio of the mirror current of the M43 tube and the M15 tube; I PT2 It is the positive temperature current generated by subthreshold MOS;

[0044] I PT1 is the positive temperature current generated by the first-order band gap;

[0045] The compensation current is extracted from R8, and the voltage after compensation is:

[0046] V ref=I PT1 (R3+R8)+V BE3 -A3R8(A1I PT2 -A2I PT1 )

[0047] =V E -ΔV CT

[0048] V ref is the voltage after low temperature compensation; I PT1 is the positive temperature current generated by the first-order band gap; I PT2 is the positive temperature current generated by the subthreshold MOS; A3 is the ratio of the mirror current of the M62 tube and the M61 tube; A1 is the ratio of the mirror current of the M41 tube and the M23 tube; A2 is the ratio of the mirror current of the M43 tube and the M15 tube; V E is the voltage after first-order compensation; ΔV CT The voltage magnitude participating in the second-order compensation in the low temperature section.

[0049] Similarly, the high temperature section adjusts the size of the current mirror to adjust the size of the replica current, thereby increasing the value of the positive temperature current generated by the first-order band gap, so that B1I in the subtraction circuit PT2 <B2I PT1 At this time, M32 will be turned on. As the temperature increases, the difference between the two currents continues to increase. Therefore, the current on M32 is a positive temperature current, and the magnitude of the positive temperature compensation current generated is:

[0050] I COMP_PT =B3(B2I PT1 -B1I PT2 )

[0051] I COMP_PT is the size of the compensation current in the high temperature stage; B3 is the ratio of the mirror current of the M63 tube and the M64 tube; B1 is the ratio of the mirror current of the M35 tube and the M23 tube; B2 is the ratio of the mirror current of the M33 tube and the M15 tube.

[0052] The compensation current is also extracted from R8, and the voltage after compensation is:

[0053] V ref =I PT1 (R3+R8)+V BE3 -B3(B2I PT1 -B1I PT2 )

[0054] =V E -ΔV PT

[0055] V ref is the voltage after high temperature compensation; IPT1 is the positive temperature current generated by the first-order band gap; I PT2 is the positive temperature current generated by the subthreshold MOS; B3 is the ratio of the mirror current of the M63 tube and the M64 tube; B1 is the ratio of the mirror current of the M35 tube and the M23 tube; B2 is the ratio of the mirror current of the M33 tube and the M15 tube; V E is the voltage after first-order compensation; ΔV CT It is the voltage magnitude participating in the second-order compensation in the high temperature section.

[0056] Beneficial effects of the present invention:

[0057] The present invention realizes segmented compensation through two positive temperature currents with different slopes (the first-order band gap also provides a positive temperature current with a larger slope, and the subthreshold positive temperature current provides a positive temperature current with a smaller slope).

[0058] In the present invention, no operational amplifier is used in the main part of the bandgap, which simplifies the circuit structure, reduces the area and reduces the manufacturing cost.

[0059] During segmented compensation, the present invention does not need to generate an independent negative temperature current. Instead, segmented compensation is performed using a subthreshold positive temperature current that does not require an operational amplifier and a positive temperature generated by a first-order band gap, thereby avoiding the use of an operational amplifier and complex frequency compensation.

[0060] The present invention utilizes segmented compensation technology to reduce the temperature drift coefficient.

[0061] The current mirrors of the present invention, such as M14 to M17; M22 to M25, etc., all use a common source and common gate structure, thereby improving the power supply rejection ratio of the output voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a circuit diagram of the present invention.

[0063] Figure 2 This is a schematic diagram of the segmented compensation principle of the present invention.

[0064] Figure 3 This is the circuit diagram of the implementation scheme closest to the present invention. DETAILED DESCRIPTION

[0065] The present invention will be described in further detail below with reference to the accompanying drawings.

[0066] Specific circuit Figure 1 As shown in FIG, the circuit is mainly composed of four parts: turn-on circuit, first-order band gap, subthreshold positive temperature current and compensation circuit.

[0067] M1 to M8 form the startup circuit, whose purpose is to eliminate the degenerate bias point of the PTAT current generation circuit, ensuring normal and stable operation. During the power-up process, the bias circuit formed by M1-M4 and M6 supplies power to the gate of transistor M8. Initially, M8 turns on, raising the potential at VBN3, allowing the PTAT current generation circuit to break free of the degenerate bias point and begin normal operation. When the PTAT current generation circuit outputs normally, a near-zero temperature voltage Vref is generated, providing gate voltage for transistor M5, causing it to begin conducting. The gate voltage of transistor M6 gradually decreases until it turns off. Simultaneously, the gate voltages of transistors M7 and M8 gradually increase until they turn off, completing the power-up process.

[0068] M14-M21, R4-R6, Q1Q2 together form a positive temperature circuit. The cascode current mirror can replace the virtual short function of the op amp, making the source voltage of M20 and M21 the same. The positive temperature current formula is:

[0069]

[0070] The current has a positive temperature coefficient, and the resistor selected is the RPPLOYU resistor with a very small temperature drift coefficient (temperature drift can be ignored). Therefore, the voltage across the resistor also has a positive temperature coefficient, while the base-emitter voltage of the transistor has a negative temperature coefficient. Adding the two voltages can obtain a voltage with nearly zero temperature drift. The formula for the first-order compensation voltage is:

[0071] V E =I PT1 (R3+R8)+V BE3

[0072] M22 to M27 and R7 together form a positive temperature current, the current magnitude is:

[0073]

[0074] M26 and M27 work in the subthreshold region. According to the characteristics of MOS in the subthreshold region, ΔV GS It has a positive temperature characteristic, so the current also has a positive temperature characteristic, and the temperature coefficient is smaller than the positive temperature characteristic of the transistor.

[0075] The first-order compensation curve is a concave curve, with the current on both sides being greater than the current in the middle. If a portion of the current on both sides is removed, the temperature drift of the curve can be reduced. Figure 2As shown, in the low-temperature stage, the cause of excessive temperature drift is an excessively large negative temperature coefficient, resulting in a negative temperature characteristic in the output voltage. Therefore, by adjusting the two positive temperature currents, the current with the high temperature coefficient is higher than the current with the high temperature coefficient. The difference between the two currents is the negative temperature current. Through M61, a portion of the negative temperature current is drawn from the output resistor to achieve temperature compensation for the low-temperature portion. Meanwhile, in the high-temperature stage, the excessively large positive temperature coefficient causes excessive temperature drift. By drawing an appropriately large positive temperature current through the input resistor, temperature compensation for the high-temperature portion is achieved.

[0076] like Figure 1 As shown, the positive temperature current I generated by the subthreshold MOS PT2 Mirror M23 M25 to the branch where M41 M42 is located, generating the size bit A1I PT2 The positive temperature current generated by the bandgap reference is I PT1 Mirror M15 M17 to M43 M44 branch, generating a size of A2I PT1 The positive temperature current is adjusted by adjusting the two coefficients, so that A1I PT2 >A2I PT1 , at this time M29 in the current subtraction circuit will be turned on, such as Figure 2 As shown, as the temperature increases, the difference between the two currents decreases continuously, so the current on M29 is a negative temperature current. If the current after mirroring through M30, M61, and M62 is A3I M29 , then the magnitude of this compensation current is:

[0077] I COMP_CT =A3(A1I PT2 -A2I PT1 )

[0078] The compensation current is extracted from R8, and the voltage after compensation is:

[0079] V E =I PT1 (R3+R8)+V BE3 -A3R8(A1I PT2 -A2I PT1 )

[0080] =V ref -ΔV CT

[0081] Similarly, in the high temperature section, the size of the current mirror is adjusted to make B1I in the subtraction circuit PT2 <B2I PT1 , at this time M32 will be turned on, such as Figure 2 As shown in the figure, as the temperature increases, the difference between the two currents continues to increase. Therefore, the current on M32 is a positive temperature current, and the magnitude of the positive temperature compensation current generated is:

[0082] I COMP_PT =B3(B2I PT1 -B1I PT2 )

[0083] The compensation current is also extracted from R8, and the voltage after compensation is:

[0084] V E =I PT1 (R3+R8)+V BE3 -B3(B2I PT1 -B1I PT2 )

[0085] =V ref -ΔV PT .

Claims

1. A bandgap reference circuit that utilizes segmented compensation technology to reduce temperature drift coefficient, characterized in that: It includes four parts: turn-on circuit, first-order band gap, subthreshold positive temperature current and compensation circuit; The turn-on circuit is used to eliminate the degenerate bias point of the PTAT current generating circuit, allowing it to operate normally and stably; The first-order band gap is used to perform first-order compensation on the output voltage, obtain a near-zero-temperature voltage, and generate a first positive temperature current; The subthreshold positive temperature current circuit is used to generate a second positive temperature current, and the slope of the second positive temperature current is smaller than the slope of the first positive temperature current; The compensation circuit processes the two positive temperature currents using a subtraction circuit, extracting the first-order compensated currents at high temperature and low temperature stages respectively to obtain an output voltage with a lower temperature coefficient. The subthreshold positive temperature current includes MOS tubes M22 to M27 and resistor R7, forming a positive temperature current, wherein the gates of M22 and M23 are connected to VBP7, and the sources of the two tubes are connected to the power supply, the drain of M22 is connected to VBP7 and the source of M24; the drain of M23 is connected to the source of M25, the gates of M24 and M25 are connected to VBP8, the drain of M24 is connected to VBP8 and the drain of M26, the drain of M25 is connected to the gate and source of M27, the gates of M26 and M27 are connected, the source of M265 is connected to R7, the other end of R7 is grounded, the gate and drain of M27 are connected, and the source is grounded; The positive temperature current is: I PT2 The current generated by the subthreshold positive temperature current; ΔV GS is the gate-source voltage difference between the two MOSFETs M26 and M27; R7 is the resistance of the branch resistor; M26 and M27 work in the subthreshold region. The gate-source voltage difference formula of MOS working in the subthreshold region is as follows: ΔV GS is the gate-source voltage difference of MOS working in the subthreshold region; V th1 and V th2 are the threshold voltages of the two MOS tubes respectively; n is the subthreshold slope correction factor; is the thermovoltage, which has a positive temperature coefficient; and is the spaciousness ratio of the two MOS tubes; According to the above formula, ΔV GS It has a positive temperature characteristic, so the current also has a positive temperature characteristic, and the temperature coefficient is smaller than the positive temperature characteristic of the transistor.

2. The bandgap reference circuit for reducing temperature drift coefficient using segmented compensation technology according to claim 1, characterized in that: The start-up circuit includes MOS transistors M1 to M8, wherein the gates of M1 to M4 are connected together and connected to the drain of M4; the source of M1 is connected to the power supply, the drain is connected to the source of M2, the drain of M2 is connected to the source of M3, the drain of M3 is connected to the source of M4, the drain of M4 is connected to the gates of M1, M2, M3, M4, M6, and the drain of M5; the gate of M5 is connected to the bandgap output voltage V ref , the source is grounded; the source of M6 is grounded, and the drain is connected to the gate and drain of M7; the source of M7 is connected to the power supply, the gate is connected to the drain of M7, the drain of M6, and the gate of M8; the gate of M8 is connected to the gate of M7, the source is connected to the power supply, and the drain is connected to the gate voltage VBN3 of M19.

3. The bandgap reference circuit for reducing temperature drift coefficient using segmented compensation technology according to claim 2, characterized in that: During the power-on process of the power supply voltage, the bias circuit composed of M1-M4 and M6 supplies power to the gate of the M8 tube. At the beginning of power-on, the M8 tube is turned on, and the potential of the VBN3 point is raised, so that the PTAT current generating circuit breaks away from the degenerate bias point and starts to work normally. When the output of the PTAT current generating circuit is normal, a near-zero temperature voltage Vref can be obtained to provide a gate voltage for the M5 tube, so that M5 starts to turn on. The gate voltage of the M6 ​​tube gradually decreases until it is turned off. At the same time, the gate voltage of the M7 and M8 tubes gradually increases until the tubes are turned off, ending the power-on process.

4. The bandgap reference circuit for reducing temperature drift coefficient using segmented compensation technology according to claim 1, characterized in that: The first-order bandgap includes a positive temperature circuit consisting of MOS tubes M14-M21, resistors R4-R6, and transistors Q1 and Q2, wherein the gates of M14, M15, and M59 are connected and connected to the drain voltage of M16, and this point voltage is named VBP9, and the sources of these three MOS are all connected to the power supply; the gates of M16, M17, and M60 are connected together and connected to the drain voltage of M18, and this point voltage is named VBP10; the drain of M14 is connected to the source of M16, and the drain of M16 is connected to R4 and the gate voltage VBP9 of M14; the drain of M15 is connected to the source of M17, and the drain of M17 is connected to R5 and the gate voltage VBN3 of M19; R4 is connected Connected between VBP9 and VBP10, R5 is connected between VBN3 and VBN4; the drain of M18 is connected to VBP10, the gate is connected to VBN3, the source is connected to the drain of M20, the gate of M20 is indirectly connected to VBN4, the source is connected to R6, the drain of M19 is connected to VBN4, the gate is connected to VBN3, the source is connected to the drain of M21, the gate of M21 is connected to VBN4, the drain is connected to the emitter of transistor Q2, the other end of R6 is connected to the emitter of transistor Q1, the bases of Q1 and Q2 are connected and grounded, the collectors of Q1 and Q2 are also grounded, the source of M59 is connected to the power supply, the gate is connected to VBP9, the drain is connected to the source of M60, the gate of M60 is connected to VBO10, and the drain is connected to V ref , one end of R3 is connected to V ref , the other end is connected to R8, the other end of R8 is connected to the emitter of transistor Q3, and the base and collector of Q3 are connected and grounded.

5. The bandgap reference circuit for reducing temperature drift coefficient by using segmented compensation technology according to claim 4, characterized in that: The MOS tubes M14 to M17 form a set of cascode current mirrors to ensure that the currents in the two branches are the same. M18 to M21 form another set of cascode current mirrors. Since the currents in the two branches are the same, the VGS of M20 and M21 are the same. Since the gates of the two tubes are connected, the source voltage is also the same, replacing the virtual short function of the op amp, so that the source voltages of M20 and M21 are the same. The positive temperature current formula is: I PT1 is the positive temperature current generated by the first-order band gap, ΔV BE is the base-collector voltage difference between the two transistors, and R6 is the resistance of the branch; The current has a positive temperature coefficient, and the resistor is selected with a very small temperature drift coefficient. Therefore, the voltage on the resistor also has a positive temperature coefficient, while the base-emitter voltage of the transistor has a negative temperature coefficient. The two voltages are added to obtain a voltage with nearly zero temperature drift. The formula for the first-order compensation voltage is: V E =I PT1 (R3+R8)+V BE3 V E is the voltage after first-order compensation; I PT1 is the positive temperature current generated by the first-order band gap; R3 and R8 are the two resistor values ​​on the output branch; V BE3 is the base-collector voltage of transistor Q3.

6. The bandgap reference circuit for reducing temperature drift coefficient using segmented compensation technology according to claim 1, characterized in that: In the compensation circuit, the gate of M33 is connected to VBP9, the source is connected to the power supply, the drain is connected to the source of M34, the gate of M34 is connected to VBP10, the drain is connected to the drain and gate of M37, the gate of M37 is connected to the gate of M39, the drain of M37 is connected to the drain and gate of M38, the gate of M38 is connected to the gate of M40, the source of M38 is grounded, the source of M40 is grounded, the drain is connected to the source of M39, the drain of M39 is connected to M The drain of M36 is connected to the drain of M32, the gate of M36 is connected to VBP8, the source is connected to the drain of M35, the gate of M35 is connected to VBP7, and the source is connected to the power supply; the gate of M38 is connected to the gate of M31, the drains of M39, M32 and M36 are connected, the source of M32 is connected to the power supply, the source of M31 is connected to the power supply, the drain is connected to the drain and gate of M64, the gate of M64 is connected to the gate of M63, the source of M64 is grounded, the source of M63 is grounded, and the drain is connected to R8; The gate of M41 is connected to VBP7, the source is connected to the power supply, the drain is connected to the source of M42, the gate of M42 is connected to VBP8, the drain is connected to the drain and gate of M45, the gate of M45 is connected to the gate of M47, the drain of M45 is connected to the drain and gate of M46, the gate of M46 is connected to the gate of M48, the source of M46 is grounded, the source of M48 is grounded, the drain is connected to the source of M47, the drain of M47 is connected to the drain of M44 and M2 The drain of M29 is connected to the gate of M30, the source of M44, M47 and M29 are connected, the source of M29 is connected to the power supply, the source of M30 is connected to the power supply, the drain is connected to the drain and gate of M62, the gate of M62 is connected to the gate of M61, the source of M62 is grounded, the source of M61 is grounded, and the drain is connected to R8.

7. The bandgap reference circuit for reducing temperature drift coefficient using segmented compensation technology according to claim 6, characterized in that: Positive temperature current I generated by subthreshold MOS PT2 Mirrored to the branch where M41 and M42 are located through M23 and M25, generating the size bit A1I PT2 The positive temperature current generated by the first-order band gap is I PT1 Mirrored to the M43 M44 branch through M15 and M17, the size is A2I PT1 The positive temperature current is adjusted by adjusting the two coefficients, so that A1I PT2 >A2I PT1 At this time, M29 in the current subtraction circuit will be turned on. As the temperature increases, the difference between the two currents continues to decrease. Therefore, the current on M29 is a negative temperature current. If the current after the mirror image through M30, M61, and M62 is A3I M29 , then the magnitude of this compensation current is: <h2 style=";text-align:left;direction:ltr">I<h2 style=";text-align:left;direction:ltr"> COMP_CT <h2 style=";text-align:left;direction:ltr"> A3(A1I)<h2 style=";text-align:left;direction:ltr"> PT2 <h2 style=";text-align:left;direction:ltr"> -A2I<h2 style=";text-align:left;direction:ltr"> PT1 <h2 style=";text-align:left;direction:ltr"> ) I COMP_CT is the magnitude of the compensation current in the low temperature stage; A3 is the ratio of the mirror current of the M62 tube and the M61 tube; A1 is the ratio of the mirror current of the M41 tube and the M23 tube; A2 is the ratio of the mirror current of the M43 tube and the M15 tube; I PT2 is the positive temperature current generated by the subthreshold MOS; I PT1 is the positive temperature current generated by the first-order band gap; The compensation current is extracted from R8, and the voltage after compensation is: V ref =I PT1 (R3+R8)+V BE3 -A3R8(A1I PT2 -A2I PT1 ) =V E -ΔV CT V ref is the voltage after low temperature compensation; I PT1 is the positive temperature current generated by the first-order band gap; I PT2 is the positive temperature current generated by the subthreshold MOS; A3 is the ratio of the mirror current of the M62 tube and the M61 tube; A1 is the ratio of the mirror current of the M41 tube and the M23 tube; A2 is the ratio of the mirror current of the M43 tube and the M15 tube; V E is the voltage after first-order compensation; ΔV CT The voltage magnitude of the low temperature section participating in the second-order compensation; Similarly, the high temperature section adjusts the size of the current mirror to adjust the size of the replica current, thereby increasing the value of the positive temperature current generated by the first-order band gap, so that B1I in the subtraction circuit PT2 <B2I PT1 At this time, M32 will be turned on. As the temperature increases, the difference between the two currents continues to increase. Therefore, the current on M32 is a positive temperature current, and the magnitude of the positive temperature compensation current generated is: I COMP_PT =B3(B2I PT1 -B1I PT2 ) I COMP_PT is the magnitude of the compensation current in the high temperature stage; B3 is the ratio of the mirror current of the M63 tube and the M64 tube; B1 is the ratio of the mirror current of the M35 tube and the M23 tube; B2 is the ratio of the mirror current of the M33 tube and the M15 tube; The compensation current is also extracted from R8, and the voltage after compensation is: V ref =I PT1 (R3+R8)+V BE3 -B3(B2I PT1 -B1I PT2 ) =V E -ΔV PT V ref is the voltage after high temperature compensation; I PT1 is the positive temperature current generated by the first-order band gap; I PT2 is the positive temperature current generated by the subthreshold MOS; B3 is the ratio of the mirror current of the M63 tube and the M64 tube; B1 is the ratio of the mirror current of the M35 tube and the M23 tube; B2 is the ratio of the mirror current of the M33 tube and the M15 tube; V E is the voltage after first-order compensation; ΔV PT It is the voltage magnitude participating in the second-order compensation in the high temperature section.

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