Ultra-low-frequency noise resistance-free band-gap reference voltage source

Abstract

The invention provides an ultra-low-frequency noise resistance-free band-gap reference power supply, which is applied to the technical field of band-gap reference power supplies, in the band-gap reference power supply, BJTs with different emitter junction areas are firstly utilized, when collectors work under equal current bias and work at different current densities, a BE junction voltage difference can be generated between two transistors, and the BE junction voltage difference can be generated between the two transistors; then, the BE junction voltage difference does not need to act on a resistor to avoid low-frequency 1 / f noise and thermal noise introduced into the resistor, that is, the BE junction voltage difference is used for lifting the potential where the base-emitter voltage of the transistor is located so as to obtain band-gap reference voltage, and finally the band-gap reference voltage can be obtained by utilizing the characteristic that the base-emitter voltage of the transistor is a negative temperature coefficient. By combining the characteristic that the BE junction voltage difference is a positive temperature coefficient, a new circuit architecture with the positive temperature coefficient and the negative temperature coefficient overlapped to achieve the compensation effect is jointly formed, and therefore the band-gap reference voltage source with the zero temperature coefficient can be obtained only by selecting proper circuit parameters.

Description

Technical Field

[0001] This application relates to the technical field of bandgap reference voltage sources, and particularly to an ultra-low low-frequency noise resistorless bandgap reference voltage source. Background Art

[0002] In high-performance application scenarios such as analog circuits, digital circuits, and mixed-signal circuits like ADC (Analog-to-Digital Converter), DAC (Digital-to-Analog Converter), sensors, and VCO (Voltage-Controlled Oscillator), an ultra-low low-frequency noise reference voltage source is usually an essential and very important functional module that significantly affects the performance of these circuits. Due to the characteristics of higher stability and lower noise, the bandgap reference voltage source is a common type of circuit unit in these circuits. The principle of the bandgap reference voltage source is: by using the negative temperature coefficient of the BE junction voltage of the BJT (Bipolar Junction Transistor) and the positive temperature coefficient voltage of the voltage difference between two BE junctions under different current densities for mutual compensation, the output voltage can achieve a very low temperature coefficient.

[0003] Currently, the circuit architecture of the bandgap reference voltage source generally realizes negative feedback compensation based on resistors. For example, poly resistors (polycrystalline silicon resistors) are used in the feedback circuit. The low-frequency 1 / f noise and thermal noise of the resistors both significantly contribute to the output low-frequency noise. Although thin-film resistors have lower 1 / f noise characteristics than poly resistors, this type of resistor has been no longer used in most processes because it will cause severe environmental pollution.

[0004] Therefore, the improvement of the low-frequency noise of the bandgap reference voltage source using resistors is restricted to some extent and cannot meet the requirements of ultra-low low-frequency noise performance. Summary of the Invention

[0005] In order to still reduce the low-frequency noise of the bandgap reference voltage source without using thin-film resistors, this application provides an ultra-low low-frequency noise resistorless bandgap reference voltage source. No resistor is used in this circuit architecture, avoiding the contribution of the low-frequency 1 / f noise and thermal noise of the resistor to the output low-frequency noise. Therefore, the low-frequency noise can be made lower, thus realizing a reference voltage with ultra-low low-frequency noise performance.

[0006] This application provides the following technical solutions: The present application provides a resistorless bandgap reference power supply with ultra-low low-frequency noise, comprising: a BE junction voltage difference generating circuit and a bandgap voltage generating circuit, wherein the BE junction voltage difference generating circuit includes a first transistor circuit, the first transistor circuit includes at least two transistors, the ratio of the emitter junction areas of the at least two transistors is N:1, and the collector inputs of the at least two transistors are biased with equal bias currents, so as to form a BE junction voltage difference when the at least two transistors operate at different current densities under equal current biasing; the bandgap voltage generating circuit includes at least one transistor, and the at least one transistor uses the BE junction voltage difference to raise the potential of the base to form a bandgap reference voltage; wherein, the emitters of the transistors that output the BE junction voltage difference among the at least two transistors and the emitters of the transistors that input the BE junction voltage difference among the at least one transistor are jointly provided with emitter bias currents by a first current source.

[0007] Preferably, the at least two transistors include a first transistor and a second transistor, the ratio of the emitter junction area of the first transistor to the emitter junction area of the second transistor is N:1, and the collectors of the first transistor and the second transistor are biased with equal currents; wherein, the base of the first transistor is connected to the base of the second transistor, and the BE junction voltage difference is output from the emitter of the first transistor; or, the base of the first transistor is connected to the collector of the second transistor, and the base of the second transistor is connected to the collector of the first transistor, so as to output the BE junction voltage difference from the emitter of the first transistor; And / or, the at least one transistor includes a fourth transistor and a fifth transistor, the ratio of the emitter junction area of the fourth transistor to the emitter junction area of the fifth transistor is 1:1, and the collectors of the fourth transistor and the fifth transistor are biased with equal currents; wherein, the base of the fourth transistor is connected to the collector of the fifth transistor, the base of the fifth transistor is connected to the collector of the fourth transistor, the emitter of the fourth transistor is provided with an emitter current by a second current source, the emitter of the fifth transistor inputs the BE junction voltage difference, and the base of the fifth transistor is used to output the bandgap reference voltage.

[0008] Preferably, the at least two transistors include a first transistor, a second transistor, a third transistor and a fourth transistor, the ratio of the emitter junction area of the first transistor to the emitter junction area of the second transistor is N:1, and the ratio of the emitter junction area of the third transistor to the emitter junction area of the fourth transistor is N:1; Among them, the base of the first transistor is connected to the collector of the second transistor and the emitter of the third transistor. The base of the second transistor is connected to the collector of the first transistor and the emitter of the fourth transistor. The emitter of the second transistor is grounded. The base and collector of the third transistor are connected to the base of the fourth transistor. The collectors of the third transistor and the fourth transistor are biased with equal currents. The emitter of the first transistor is used to output the BE junction voltage difference; And / or, the at least one transistor includes a forty-first transistor, a forty-second transistor, a forty-third transistor, and a forty-fourth transistor. The ratio of the emitter junction area of the forty-first transistor to the emitter junction area of the forty-second transistor is 1:1. The ratio of the emitter junction area of the forty-third transistor to the emitter junction area of the forty-fourth transistor is 1:1. The collectors of the forty-third transistor and the forty-fourth transistor are biased with equal currents. Among them, the base of the forty-first transistor is connected to the collector of the forty-second transistor and the emitter of the forty-third transistor. The base of the forty-second transistor is connected to the collector of the forty-first transistor and the emitter of the forty-fourth transistor. The base and collector of the forty-third transistor are connected to the base of the forty-fourth transistor. The emitter of the forty-first transistor is provided with emitter current by a second current source. The emitter of the forty-second transistor inputs the BE junction voltage difference. The base of the forty-second transistor outputs the bandgap reference voltage.

[0009] Preferably, the at least two transistors include a first transistor, a second transistor, a third transistor, and a fourth transistor. The ratio of the emitter junction area of the first transistor to the emitter junction area of the second transistor is N:1. The ratio of the emitter junction area of the third transistor to the emitter junction area of the fourth transistor is N:1; Among them, the base of the first transistor is connected to the collector of the second transistor and the emitter of the third transistor. The base of the second transistor is connected to the collector of the first transistor and the emitter of the fourth transistor. The emitter of the second transistor is grounded. The base and collector of the third transistor are connected to the base of the fourth transistor. The collectors of the third transistor and the fourth transistor are biased with equal currents. The emitter of the first transistor is used to output the BE junction voltage difference; And / or, the at least one transistor includes a fourth one transistor, a fourth two transistor, a fourth three transistor, and a fourth four transistor. The ratio of the emitter junction area of the fourth one transistor to the emitter junction area of the fourth two transistor is 1:1. The ratio of the emitter junction area of the fourth three transistor to the emitter junction area of the fourth four transistor is 1:1. The collectors of the fourth three transistor and the fourth four transistor are biased with equal current. Wherein, the base of the fourth one transistor is connected to the collector of the fourth two transistor and the emitter of the fourth three transistor. The base of the fourth two transistor is connected to the collector of the fourth one transistor and the emitter of the fourth four transistor. The base and the collector of the fourth three transistor are connected to the base of the fourth four transistor. The emitter of the fourth one transistor is supplied with emitter current by a second current source. The emitter of the fourth two transistor inputs the BE junction voltage difference. The base of the fourth two transistor outputs the bandgap reference voltage.

[0010] Preferably, the first transistor circuit further includes a first one operational amplifier and a first one bias current source. Wherein, the first one bias current source is used to provide a first bias current. The first one bias current source is connected in series between the first input terminal of the first one operational amplifier and the power supply terminal. The second input terminal of the first one operational amplifier is connected to the output terminal of the first one operational amplifier. After being respectively connected to the collectors of the at least two transistors through the first input terminal and the second input terminal of the first one operational amplifier, equal first bias current is provided to the collectors of the at least two transistors. And / or, when there is more than one transistor in the at least one transistor, the bandgap voltage generation circuit further includes a fourth one operational amplifier and a fourth one bias current source. Wherein, the fourth one bias current source is used to provide a current equal to the first bias current. The fourth one bias current source is connected in series between the first input terminal of the fourth one operational amplifier and the power supply terminal. The second input terminal of the fourth one operational amplifier is connected to the output terminal of the fourth one operational amplifier. After being respectively connected to the collectors of the at least one transistor of more than one transistor through the first input terminal and the second input terminal of the fourth one operational amplifier, equal bias current is provided to the collectors of the at least one transistor.

[0011] Preferably, the circuit structure of the first one operational amplifier and / or the fourth one operational amplifier includes a differential operational amplifier. The differential operational amplifier includes a PNP differential pair transistor, a first current mirror, a second current mirror, a transistor current source, an RC branch, and an amplification transistor. Wherein, the bases of the PNP differential pair transistors are respectively used as the differential input terminals of the operational amplifier. The collectors of the PNP pair transistors are supplied with bias current by the transistor current source. The emitters of the PNP differential pair transistors are respectively provided with emitter current by the first current mirror as a long-tail current source after passing through resistors. The RC branch is connected across the gate and the drain of the amplification transistor. The gate of the amplification transistor is connected to the collector of one of the PNP differential pair transistors. The source of the amplification transistor is grounded. The drain of the amplification transistor is supplied with bias current by the second current mirror. The drain of the amplification transistor is used as the output terminal of the operational amplifier.

[0012] Preferably, the BE junction voltage difference generating circuit further includes a second transistor circuit, and the circuit structure formed by the transistors in the second transistor circuit is the same as the circuit structure formed by the transistors in the first transistor circuit; wherein, the emitter of the transistor that outputs the BE junction voltage difference among the at least two transistors in the first transistor circuit is connected to the emitter of the transistor that inputs the BE junction voltage difference among the at least two transistors in the second transistor circuit and is provided with emitter current by a first current source, and the emitter of the transistor that outputs the BE junction voltage difference among the at least two transistors in the second transistor circuit and the emitter of the transistor that is used to input the BE junction voltage difference among the at least one transistor are jointly provided with emitter current by a second current source having the same current as the first current source, so that the second transistor circuit is connected in series between the first transistor circuit and the bandgap voltage generating circuit.

[0013] Preferably, the BE junction voltage difference generating circuit further includes a third transistor circuit, and the circuit structure formed by the transistors in the third transistor circuit is the same as the circuit structure formed by the transistors in the first transistor circuit; wherein, the emitter of the transistor that outputs the BE junction voltage difference among the at least two transistors in the second transistor circuit is connected to the emitter of the transistor that inputs the BE junction voltage difference among the at least two transistors in the third transistor circuit and is provided with emitter current by a second current source, and the emitter of the transistor that outputs the BE junction voltage difference among the at least two transistors in the third transistor circuit and the emitter of the transistor that is used to input the BE junction voltage difference among the at least one transistor are jointly provided with emitter current by a third current source having the same current as the first current source, so that the third transistor circuit is connected in series between the second transistor circuit and the bandgap voltage generating circuit.

[0014] Preferably, the first current source includes a reference current source and a current mirror, wherein the current of the reference current source is equal to the collector current of the at least two transistors, and the reference current source is connected in series between the current mirror and the power supply terminal, and the current mirror is used to copy the current of the reference current source to provide the emitter bias current.

[0015] Preferably, when the current used to bias the collectors of the at least two transistors is equal to the current used to bias the collector of the at least one transistor, the current mirror includes a first current mirror transistor and a second current mirror transistor, the ratio of the emitter junction area of ​​the first current mirror transistor to the emitter junction area of ​​the second current mirror transistor is 1:2, the collector and base of the first current mirror transistor are connected to the base of the second current mirror transistor to input the current provided by the reference current source, the emitter of the first current mirror transistor and the emitter of the second current mirror transistor are grounded, and the collector of the second current mirror transistor is used to provide the emitter bias current.

[0016] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the present application include at least: The present application proposes an ultra-low low-frequency noise non-resistance bandgap reference power supply. In the architecture of the bandgap reference power supply, no resistors are used, so the low-frequency 1 / f noise and thermal noise of the resistors no longer contribute to the output low-frequency noise, thereby obtaining a bandgap reference voltage with smaller low-frequency noise. Since no resistors are used and all circuits are designed with BJTs, the 1 / f noise of the BJT itself is very low, close to the thermal noise, and the BJT thermal noise is lower than that of ordinary MOS, and the overall 1 / f noise is easy to achieve. For example, in the circuit design of the present application, the static current is 120uA, the output is 1.2V, and the integrated noise from 0.1Hz to 10Hz is only 1.5uVpp.

[0017] Therefore, the present application can achieve excellent performance of ultra-low low-frequency noise by adopting a bandgap reference voltage source implemented by a resistor-free architecture, which well meets the application requirements of higher precision and lower noise application scenarios that require the reference voltage source to have ultra-low low-frequency noise, and also improves the low-frequency noise performance of the reference voltage source to a higher level, making the reference voltage source adaptable to more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a structural schematic diagram of a bandgap reference voltage source in the prior art; Figure 2 It is a structural schematic diagram of an ultra-low low-frequency noise non-resistance bandgap reference power supply in the present application; Figure 3 This is a schematic diagram of a structure based on two transistors generating a BE junction voltage difference in this application; Figure 4 It is another structural schematic diagram for generating the BE junction voltage difference based on two transistors in this application; Figure 5 It is a structural schematic diagram for generating the BE junction voltage difference based on four stacked transistors in this application; Figure 6 It is a structural schematic diagram for a current source combined with an operational amplifier to provide a collector bias current in this application; Figure 7 It is a structural schematic diagram of an ultra-low low-frequency noise resistorless bandgap reference power supply for generating the BE junction voltage difference and the bandgap reference voltage based on multiple stacked transistors in this application; Figure 8 It is a structural schematic diagram of an operational amplifier based on differential second-stage amplification in this application; Figure 9 It is a structural schematic diagram of an ultra-low low-frequency noise resistorless bandgap reference power supply formed by multi-stage cascading in this application. Detailed implementation manners

[0020] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0021] The following illustrates the implementation manners of the present application through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0022] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects described herein can be used to implement the device and / or practice the method. Additionally, this device and / or this method can be implemented using other structures and / or functionality in addition to one or more of the aspects described herein.

[0023] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application schematically. The diagrams only show the components related to the present application, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and ratios of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0024] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the practice can be carried out without these specific details.

[0025] Referring Figure 1 to the schematic, in a traditional structure of a bandgap reference voltage source, the principle of implementing the bandgap reference voltage source is as follows: By using the negative temperature coefficient of the BE junction voltage of the BJT and the positive temperature coefficient voltage of the voltage difference between two BE junctions under different current densities for mutual compensation, the output bandgap reference voltage V BG can achieve a very low temperature coefficient. Further, in order to achieve an even lower temperature coefficient, usually in the circuit structure, the voltage difference between the two BE junctions acts on the resistor R2, is converted into a current flowing into the resistor R1, and the high-gain operational amplifier A1 is used to amplify the voltage difference between the two BE junctions, where the amplification factor is R2 / 2R1, and N is the ratio of the emitter areas of the selected BJTs (i.e., Q2 and Q1).

[0026] Regarding Figure 1 the traditional circuit design scheme shown (i.e., the bandgap reference voltage source using NPN transistors and resistors), assuming that the resistor R4 = R5, and the ratio of the emitter areas of Q2 and Q1 is N:1. The high-gain operational amplifier A1 and Q1, Q2, R1, and R2 together form a negative feedback loop, making the input of the operational amplifier virtually short-circuited, so that the collector currents of Q2 and Q1 can be kept equal.

[0027] Through derivation, the output bandgap reference voltage can be obtained as: (1) It can be seen from the above formula (1) that in the scheme for achieving low temperature drift, in the second term, Vt = kt / q is a first-order positive temperature coefficient, and in the first term, the junction voltage V BE is a term that varies with current , and the variation with current can be expressed as the following formula (2): (2) In the formula is the reference temperature, generally referring to room temperature; is a process constant, characterizing the temperature change influence coefficient of the BJT current density, and different processes have different values, generally 3 - 6.

[0028] From the combination of the above equations (1) and (2), the advantages and disadvantages of the circuit are as follows: The advantages of this architecture are: by selecting the most appropriate ratio of R1 and R2, and the transistor emitter area ratio N, a bandgap reference with zero temperature coefficient can be obtained.

[0029] Similarly, the main disadvantage of this architecture is that the noise of the R1 and R2 resistors will be directly amplified and significantly contribute to the output reference voltage, that is, the low-frequency noise of both the R1 and R2 resistors will directly have an obvious contribution to the output reference voltage. In particular, the 1 / f noise of the poly resistor in the traditional process contributes greatly to the low-frequency integrated noise from 0.1 to 10 Hz.

[0030] Regarding the influence of the low-frequency noise brought by the resistor, the current common technical route in the industry is as follows: In some solutions, increasing the current can reduce the high-frequency thermal noise, and the low-frequency noise can only be reduced by increasing the area. Usually, when the area is increased to a large enough extent, the low-frequency noise will also reach a limit. The cost of achieving ultra-low low-frequency noise by using the resistor-based bandgap reference is unacceptable and difficult to achieve.

[0031] In individual solutions, in order to solve the influence of resistor noise, low-1 / f thin-film resistors can be used, but such resistors are no longer provided in most processes.

[0032] It should be noted that the above analysis is based on the relatively typical Brokaw bandgap reference circuit structure in the prior art for analysis, but other similar bandgap references that use resistors to form the bandgap reference voltage also have similar problems, that is, the resistors used contribute relatively obvious low-frequency noise to the bandgap reference voltage, making it difficult for the bandgap reference to reach the ultra-low low-frequency noise level.

[0033] In view of this, through in-depth research and improvement exploration of the bandgap reference voltage source, it is found that: as described in the above analysis, the bandgap reference voltage source utilizes the voltage difference of the BE junction acting on the resistor to form the bandgap reference voltage. If the bandgap reference voltage source does not use a resistor, that is, the existing circuit architecture based on the resistor-type bandgap reference voltage source is improved to a resistorless circuit architecture, then the resistorless circuit architecture should be able to avoid the influence of the low-frequency noise of the resistor on the output reference voltage, thereby realizing a bandgap reference voltage source with ultra-low low-frequency noise based on the resistorless architecture.

[0034] Reference Figure 2 As shown in the schematic, this application proposes a resistorless circuit architecture for an ultra-low low-frequency noise bandgap reference voltage source. The design idea of the circuit architecture is as follows: On the one hand, in terms of forming the base-emitter junction voltage difference using BJT transistors, it can still be similar to the traditional BJT structure scheme, that is, using BJTs with different emitter junction areas to generate the base-emitter junction voltage difference. Specifically, by biasing the same current to two BJT transistors, the two transistors are operated at different current densities, thereby forming the difference in base-emitter voltage between the two transistors (i.e., the base-emitter junction voltage difference). It should be noted that the BJT circuit architecture for forming the base-emitter junction voltage difference can be one of the structure forms schematically shown above Figure 1 , or other structure forms, or even the circuit structure forms in other improved preferred embodiments provided in the following text of this application.

[0035] On the other hand, in terms of forming the bandgap reference voltage using the base-emitter junction voltage difference, it is no longer like the traditional scheme of applying the base-emitter junction voltage difference to a resistor (such as the example above Figure 1 , or the bandgap reference voltage source-related architectures in other existing technologies). In this application, the base-emitter junction voltage difference is used to raise the potential of the base-emitter voltage of the transistor, that is, by applying the base-emitter junction voltage difference to the subsequent stage transistor circuit, thereby using the base-emitter junction voltage difference to raise the base potential of the transistor to obtain the bandgap reference voltage. Finally, the negative temperature coefficient characteristic of the base-emitter voltage of the transistor can be combined with the positive temperature coefficient characteristic of the base-emitter junction voltage difference to jointly form a circuit architecture with the superposition effect of positive and negative temperature coefficients, so as to achieve the mutual compensation of positive and negative temperature coefficients, that is, by selecting appropriate circuit parameters (such as the parameter N of the emitter junction area ratio of the transistors generating the base-emitter junction voltage difference in the example above Figure 1 ) to obtain a bandgap reference voltage source with zero temperature coefficient.

[0036] As Figure 2 shown, the base-emitter junction voltage difference generation circuit 100 is used to generate the base-emitter junction voltage difference ( ), and the bandgap reference voltage generation circuit 200 is used to generate the bandgap reference voltage V BG using this base-emitter junction voltage difference. Specifically, in the base-emitter junction voltage difference generation circuit 100, by using two transistors Q11 and Q12 with different emitter junction areas and biasing equal current I 1 to the collectors of the transistors, the base-emitter junction voltage difference (i.e., ) is generated by operating these two transistors at different current densities. After obtaining the base-emitter junction voltage difference, this base-emitter voltage difference is applied to the subsequent stage transistor circuit (i.e., the bandgap reference voltage generation circuit 200); in the bandgap reference voltage generation circuit 200, the base potential of the transistor Q41 is raised using this base-emitter voltage difference, thereby using the negative temperature coefficient of the base-emitter voltage V BE of the transistor Q41, combined with the base-emitter junction voltage difference It is a positive temperature coefficient. Only by selecting appropriate circuit parameters (such as the parameter N of the emitter junction area ratio) can a bandgap reference voltage with zero temperature coefficient be obtained.

[0037] It should be noted that the generation of the BE junction voltage difference The circuit architecture form of the BE junction voltage difference generation circuit 100 that generates the BE junction voltage difference can be the BJT pair transistor circuit architecture used in the prior art to generate the BE junction voltage difference, or the preferred circuit architecture form in the improved preferred embodiment provided in this application hereinafter. Therefore, although Figure 2 does not show the specific circuit connections of the two transistors in the BE junction voltage difference generation circuit 100, it does not affect those skilled in the art to understand the foregoing technical idea of this application - using the BJT operating at different current densities to provide .

[0038] Similarly, using the BE junction voltage difference to generate the bandgap reference voltage V BG The circuit architecture form of the bandgap reference voltage generation circuit 200 can be the circuit structure of a traditional single transistor, or the preferred circuit architecture form in the improved preferred embodiment provided in this application hereinafter using at least one transistor. Therefore, although Figure 2 does not show the specific circuit connections of the transistors in the bandgap reference voltage generation circuit 200, it does not affect those skilled in the art to understand the foregoing technical idea of this application - using to raise the base potential of the BJT to obtain a stable temperature coefficient (or zero temperature coefficient) bandgap reference voltage.

[0039] In addition, Figure 2 the bias currents I 1 and I 2 of the transistors in can be equal or unequal currents. If equal bias currents are used, it can further simplify the current source circuit design in the overall circuit, thus facilitating the overall circuit architecture design. Therefore, the bias current is not specifically limited, but those skilled in the art should understand the foregoing technical idea of this application.

[0040] In summary, compared with the circuit architecture of the traditional bandgap reference voltage source, in the new circuit architecture of the bandgap reference voltage source improved by using the BJT in this application, since no resistor is used, the low-frequency 1 / f noise and thermal noise of the resistor will not contribute relevant low-frequency noise to the output bandgap reference voltage, enabling the bandgap reference voltage source to achieve a very low (i.e., ultra-low) low-frequency noise level.

[0041] Moreover, since no resistor is used and all circuits are designed with BJTs, and the 1 / f noise of the BJT itself is very low, close to thermal noise, and the thermal noise of the BJT is lower than that of ordinary MOS transistors, the overall 1 / f noise can be easily achieved.

[0042] The following will describe the technical solutions provided by the embodiments of the present application with reference to the accompanying drawings.

[0043] As Figure 2 shown, the present application provides an ultra-low low-frequency noise resistorless bandgap reference voltage source, which may include: a BE junction voltage difference generation circuit 100 and a bandgap voltage generation circuit 200, wherein the BE junction voltage difference generation circuit 100 is used to provide a base-emitter voltage difference (i.e., BE junction voltage difference, ), and the bandgap voltage generation circuit 200 is used to generate a bandgap reference voltage V BG .

[0044] In implementation, the BE junction voltage difference generation circuit 100 includes a first transistor circuit, and the first transistor circuit may include at least two transistors (such as Figure 2 Q11 and Q12 shown in the schematic), the emitter junction area ratio of the at least two transistors is N:1, and the collector inputs of the at least two transistors are equal bias currents (such as Figure 2 bias current I 1 shown in the schematic), so as to form a BE junction voltage difference by using the at least two transistors operating at different current densities under equal current bias.

[0045] As analyzed above, the first transistor circuit may be two transistors (such as NPN transistors) Q11 and Q12 with the same collector bias and operating at different current densities, and then output a BE junction voltage difference at the emitter to obtain .

[0046] In implementation, the bandgap voltage generation circuit 200 may include at least one transistor, and the at least one transistor uses the BE junction voltage difference to lift the potential of the base to form a bandgap reference voltage.

[0047] Referring to Figure 2 the schematic, from the perspective of the BE junction voltage difference generation circuit 100, the emitter of one of the at least two transistors (such as Figure 2 Q11 shown in the schematic) used to generate the BE junction voltage difference is used to output the BE junction voltage difference, and from the perspective of the bandgap voltage generation circuit 200, the transistor (such as Figure 2The schematic Q41), whose emitter is connected to the emitter that outputs the BE junction voltage difference in the BE junction voltage difference generation circuit 100, and is jointly provided with the emitter bias current by the first current source (such as Figure 2 The schematic current source I 3 ), so that the base potential of the transistor Q41 in the bandgap voltage generation circuit 200 is lifted under the action of the BE junction voltage difference (i.e., V1), forming the output of the bandgap reference voltage V BG . Among them .

[0048] In summary, in this application, the BE junction voltage difference is generated by the BJT, and then the BE junction voltage difference is used to lift the base potential of the transistor by acting on the emitter of the next-stage BJT, so as to obtain the bandgap reference voltage: . Since is the base-emitter voltage of the transistor Q41 and has a negative temperature coefficient, while the BE junction voltage difference has a positive temperature coefficient, so only by selecting appropriate circuit parameters (such as the emitter junction area ratio N, or the coefficients in V BG in and / or etc.), a bandgap reference voltage with zero temperature coefficient can be obtained by mutual compensation of positive and negative temperature coefficients.

[0049] In some embodiments, the first transistor circuit for generating the BE junction voltage difference adopts a circuit architecture composed of two transistors.

[0050] Figure 3 Illustrates a circuit architecture, where the two transistors are respectively denoted as the first transistor Q11 and the second transistor Q12, and the ratio of the emitter junction areas of Q11 and Q12 is N:1. The base and collector of Q11 are connected to the base of Q12, the emitter of Q12 is grounded, and by inputting equal bias currents I 1 to the collectors of the two transistors, and providing a stable emitter current for the emitter based on the current source, a BE junction voltage difference is formed on the emitter of Q11 by using the two transistors operating at different current densities: .

[0051] Figure 4 Illustrates another circuit architecture. The same as Figure 3 is the characteristics of the transistors, that is, the two transistors are respectively denoted as the first transistor Q11 and the second transistor Q12, and the ratio of the emitter junction areas of Q11 and Q12 is N:1. The difference is the connection relationship of the transistors, that is, the transistors are cross-connected, where the base of Q11 is connected to the collector of Q12, the base of Q12 is connected to the collector of Q11, the emitter of Q12 is grounded, and by inputting equal bias currents I1 , and a stable emitter current is provided for the emitter based on a current source, so that the two transistors operate at different current densities to obtain a BE junction voltage difference at the emitter of Q11 .

[0052] It should be noted that the current source that provides current for the emitter can be a reference current source or a current mirror. Improved preferred examples are provided later and can be used as a reference.

[0053] In some embodiments, the first transistor circuit for generating the BE junction voltage difference adopts a circuit architecture composed of four transistors. For example, by Figure 3 and Figure 4 stacking the two transistor circuit architectures, the BE junction voltage difference that can be output is twice that before stacking.

[0054] Referring to Figure 5 for illustration, first design a circuit architecture for generating the BE junction voltage difference by two transistors as shown in Figure 4 , that is, composed of two NPNs Q11 and Q12, and the ratio of the emitter areas is N:1. By biasing two equal currents, the voltage difference of the BE junction between the two NPNs can be generated: . Then, design a circuit architecture one for generating the BE junction voltage difference by two transistors as shown in Figure 3 , that is, composed of two NPNs Q13 and Q14 as shown in Figure 3 the circuit architecture shown, and then stack it on the Figure 4 circuit architecture. By biasing two equal currents I 1 for the stacked circuit architecture, that is, inputting equal currents I 1 to the collectors of Q13 and Q14, a corresponding BE junction voltage difference is generated at the emitter of Q11, that is, the BE junction voltage difference output by the stacked circuit architecture becomes twice that of the original single architecture: .

[0055] In addition, by stacking to obtain a new circuit architecture, in addition to the foregoing Figure 5 example shown, it can also be stacking the Figure 4 circuit on the Figure 3 circuit to obtain a new circuit architecture, or even stacking two or more circuits, which will not be elaborated here.

[0056] In summary, by forming a new circuit architecture in a stacked manner with a circuit architecture composed of multiple transistors, a BE junction voltage difference that is multiple times that of the original single architecture can be obtained, further improving the flexibility of parameter setting for adjusting the temperature coefficient of the bandgap reference voltage to zero temperature coefficient.

[0057] In some embodiments, for the transistor collector bias that generates the BE junction voltage difference, a current source can be used for biasing, or the improved preferred examples provided below can be used.

[0058] Reference Figure 6 As shown in the schematic, in the first transistor circuit that generates the BE junction voltage difference, by adding an operational amplifier and a current source, that is, the first transistor circuit includes the first operational amplifier A11 and the first bias current source I 1 , a stable and equal biasing circuit is provided for the collectors of the two transistors. Among them, the first bias current source I 1 is used to provide the first bias current I 1 , the first bias current source I 1 is connected in series between the first input terminal of the first operational amplifier A11 and the power supply terminal. The second input terminal of the first operational amplifier A11 is connected to the output terminal of the first operational amplifier A11, so as to form a follower using A11. After the first input terminal and the second input terminal of A11 are respectively connected to the collectors of the two transistors, by using the "virtual short and virtual open" of the operational amplifier, the two transistors work under the condition that the collector voltages are equal, that is, the working conditions of the two transistors are kept the same, and an equal biasing current I 1 can be provided to the collectors of the two transistors. In this way, the transistor is not likely to generate linear errors, and a BE junction voltage difference without nonlinear errors is realized.

[0059] As analyzed above, in this application, the base potential of the transistor is lifted by using the BE junction voltage difference to generate the bandgap reference voltage. Therefore, the transistors in the bandgap reference voltage generation circuit 200 can be one or more. Some improved preferred examples are provided for the bandgap reference voltage generation circuit 200 below.

[0060] In some embodiments, two transistors are used to form the circuit architecture in the bandgap reference voltage generation circuit 200.

[0061] Reference Figure 7 As shown in the schematic, the two-transistor circuit architecture formed by using the transistor Q41 (denoted as the forty-first transistor) and Q42 (denoted as the forty-second transistor) is as follows: the emitter junction areas of Q41 and Q42 are in a ratio of 1:1, and the collectors of Q41 and Q42 are biased with equal current I 2 , the two transistors are connected in a cross-connected manner, that is, the base of Q41 is connected to the collector of Q42, the base of Q42 is connected to the collector of Q41, the emitter of Q41 is provided with the emitter current by the second current source (such as the current mirror formed by Q40 and Q0), and the emitter of Q42 inputs the BE junction voltage difference generated by the BE junction voltage difference generation circuit 100, then the base of Q42 is used to output the bandgap reference voltage V BG .

[0062] The bandgap reference voltage generation circuit 200 is designed as a two-transistor circuit structure, which is composed of two NPN transistors, Q41 and Q42, with an emitter area ratio of 1:1. The base potential is lifted by using the BE junction voltage difference to obtain the bandgap reference voltage.

[0063] In some embodiments, four transistors are used to form the circuit architecture in the bandgap reference voltage generation circuit 200.

[0064] The bandgap reference voltage generation circuit 200 is designed as a first transistor circuit similar to that composed of four transistors, that is, a new circuit architecture is formed by stacking: a four-transistor circuit architecture composed of transistors Q41 (denoted as the forty-first transistor), Q42 (denoted as the forty-second transistor), Q43 (denoted as the forty-third transistor), and Q44 (denoted as the forty-fourth transistor).

[0065] In implementation, first design a two-transistor circuit, specifically referring to Figure 7 the circuit structure composed of Q41 and Q42 shown in the schematic, and then design another two-transistor circuit, specifically referring to Figure 7 the circuit structure composed of Q43 and Q44 shown in the schematic, and then stack the two transistor circuits to form a four-transistor circuit architecture.

[0066] Refer to Figure 7 As shown in the schematic, the emitter junction area ratio of Q41 and Q42 is 1:1, the emitter junction area ratio of the forty-first transistor to the forty-second transistor is 1:1, the collectors of Q43 and Q44 are biased with equal currents, the base of Q41 is connected to the collector of Q42 and the emitter of Q43, the base of Q42 is connected to the collector of Q41 and the emitter of Q44, the base and collector of Q43 are connected to the base of Q44, the emitter of Q41 is provided with an emitter current by the second current source, the BE junction voltage difference is input to the emitter of Q42, and the bandgap reference voltage is output from the base of Q42.

[0067] The current values flowing through Q41 and Q42 are the same, the current values flowing through Q43 and Q44 are the same, and the input BE junction voltage difference (such as Figure 7 V1 in ) is superimposed on the Vbe of Q42, then the output voltage is

[0068] Therefore, since has a negative temperature coefficient and the BE junction voltage difference has a positive temperature coefficient, so by reasonably setting the value of N, a bandgap reference voltage V BG with zero temperature coefficient can be obtained.

[0069] In some embodiments, the collector currents of the transistors in the bandgap reference voltage generation circuit 200 can adopt a current supply method similar to that of the first transistor circuit, that is, a current source and an operational amplifier are used to provide equal bias currents I for the collectors of the two transistors. 2 .

[0070] Reference Figure 7 Schematic illustration, the current source is connected in series between the fourth operational amplifier A4 and the power supply terminal. The operational amplifier A44 is connected in a follower configuration and used as a voltage buffer. Thus, stable and equal bias currents are obtained at the collectors of Q43 and Q44 respectively. By using the operational amplifier as a voltage buffer, the emitter voltages of Q43 and Q44 are made equal, ensuring that the operating conditions of Q43 and Q42 are the same and there is no nonlinear error.

[0071] In some embodiments, the operational amplifier serving as the voltage buffer can adopt a traditional circuit structure or an improved priority example provided in the present application.

[0072] Reference Figure 8 Schematic illustration, the present application provides an operational amplifier structure with a differential circuit architecture, including: a PNP differential pair transistor composed of Q100 and Q200, a first current mirror composed of M1 and M0, a second current mirror composed of M2 and M0, a transistor current source composed of Q300 and Q400, an RC branch composed of a resistor R and a capacitor C connected in series, and an amplifying transistor M3. The specific connection relationship is illustrated as follows: In the PNP differential pair transistor composed of Q100 and Q200, the bases of the two transistors serve as the differential input terminals INP and INN of the operational amplifier respectively. The collectors of the PNP pair transistors are provided with bias currents by the transistor current source. The emitters of the PNP differential pair transistors are respectively passed through resistors R1 and R2, and then the first current mirror serves as a long-tail current source to provide emitter currents. The RC branch is connected across the gate and drain of the amplifying transistor M3. The gate of the amplifying transistor M3 is connected to the collector of one transistor Q200 in the PNP differential pair transistor. The source of the amplifying transistor M3 is grounded. The drain of the amplifying transistor M3 is provided with a bias current by the second current mirror. The drain of the amplifying transistor M3 serves as the output terminal OUT of the operational amplifier.

[0073] By adopting a two-stage operational amplifier structure design of differential pair transistor + amplifying transistor, that is, using BJT transistors as the input pair transistors, when the current amplification factor of the input pair transistors is relatively large, the operational amplifier has the advantages of low offset voltage and small offset temperature drift, and can meet the application requirements with high requirements for input current and voltage offset.

[0074] In some embodiments, by adopting a multi-stage cascaded circuit architecture such as the first transistor circuit architecture, an integer multiple of the BE junction voltage difference of the original single architecture can be further obtained.

[0075] Reference Figure 9 Schematic illustration, similar toFigure 5 The number of stages of the first transistor circuit is three, where the first stage is composed of Q11 - Q14 to form the aforementioned Figure 5 stacked structure, and the output BE - junction voltage difference is: ; the second stage is composed of Q21 - Q24 to form the aforementioned Figure 5 stacked structure, and the output BE - junction voltage difference is: ; the third stage is composed of Q31 - Q34 to form the aforementioned Figure 5 stacked structure, and the output BE - junction voltage difference is: ; the finally obtained band - gap reference voltage is: . Therefore, from the expression of the finally output band - gap reference voltage, it can be known that: by selecting a reasonable value of N, a band - gap reference voltage with zero temperature coefficient can be obtained.

[0076] As Figure 8 shown in a circuit architecture, its working principle is shown as follows: First - stage circuit: When the current values flowing through Q11 and Q12 are the same, the V BE difference between them is ; when the current values flowing through Q13 and Q14 are the same, the V BE difference between them is . Therefore, the voltage at point V1 is .

[0077] In addition, the current flowing through Q10 is provided by a current source (such as the current mirror of Q10 and Q0), which is 2 times the reference current, which can ensure that the current values flowing through Q11 and Q12 are the same, and through a voltage buffer (i.e., the first operational amplifier A11), the collector voltages of Q13 and Q14 are made equal, ensuring that the working conditions of Q13 and Q14 are the same and there is no non - linear error.

[0078] Second - stage circuit: When the current values flowing through Q21 and Q22 are the same, the V BE difference between them is ; when the current values flowing through Q23 and Q24 are the same, the V BE difference between them is . Therefore, the voltage at point V2 in the figure is .

[0079] In addition, the current flowing through Q20 is provided by a current source (such as the current mirror of Q20 and Q0), which is 2 times the reference current, which can ensure that the current values flowing through Q21 and Q22 are the same, and through a voltage buffer (i.e., the second operational amplifier A21), the collector voltages of Q23 and Q24 are made equal, ensuring that the working conditions of Q23 and Q24 are the same and there is no non - linear error.

[0080] Second - stage circuit: When the current values flowing through Q31 and Q32 are the same, the difference in VBE between Q31 and Q32 can be obtained as ; when the current values flowing through Q33 and Q34 are the same, the difference in VBE between Q33 and Q34 can be obtained as . Therefore, the voltage at point V3 in the figure is . In addition, the current flowing through Q30 is provided by a current source (such as the current mirror of Q30 and Q0), which is 2 times the reference current. This can ensure that the current values flowing through Q31 and Q32 are the same, and through a voltage buffer (i.e., the third operational amplifier A31), the collector voltages of Q33 and Q34 are equal, ensuring that the operating conditions of Q33 and Q34 are the same without non - linear errors.

[0081] It should be noted that the number of stages can be selected according to the coefficient requirement of the band - gap reference voltage for the BE - junction voltage difference term; similarly, the circuit architecture of stacking after generating the BE - junction voltage difference using two transistors in each stage can be selected according to the coefficient requirement of the band - gap reference voltage for the BE - junction voltage difference term.

[0082] Therefore, for the multi - stage cascaded circuit architecture composed of transistor circuits generating the BE - junction voltage difference, the number of stages can be a three - stage structure as Figure 9 schematically shown, or a single - stage, two - stage, or more - than - three - stage structure, etc. Among them, in the multi - stage cascade, the BE - junction voltage difference output from the emitter of the previous - stage circuit serves as the emitter input of the next - stage circuit.

[0083] In some embodiments, the current source providing current for the emitters of the transistors in the BE - junction voltage difference generating circuit 100 and the band - gap reference voltage generating circuit 200 can be a reference current source or the BJT current source of the improved preferred example provided in this application.

[0084] Refer to Figure 9 schematic, the current source providing a stable bias current for the emitters of transistors such as Q11, Q21, Q22, Q31, Q32, Q41, Q42, etc. can be provided by a current mirror composed of BJTs.

[0085] For example, the current flowing through Q10 is provided by the current mirror of Q10 and Q0, which is 2 times the reference current, and this can ensure that the current values flowing through Q11 and Q12 are the same.

[0086] For example, the current flowing through Q20 is provided by the current mirror of Q20 and Q0, which is 2 times the reference current, and this can ensure that the current values flowing through Q21 and Q22 are the same.

[0087] For example, the current flowing through Q30 is provided by the current mirror of Q30 and Q0 and is twice the reference current, which can ensure that the current values flowing through Q31 and Q32 are the same.

[0088] For example, the current flowing through Q40 is provided by the current mirror of Q40 and Q0 and is twice the reference current, which can ensure that the current values flowing through Q41 and Q42 are the same.

[0089] In this specification, for the same or similar parts among the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and reference can be made to the corresponding parts of the foregoing embodiments for relevant matters.

[0090] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An ultra-low low-frequency noise resistance-free bandgap reference power supply, characterized in that: include: A BE junction voltage difference generating circuit and a bandgap voltage generating circuit, wherein the BE junction voltage difference generating circuit comprises a first transistor circuit, the first transistor circuit comprises at least two transistors, the emitter junction area ratio of the at least two transistors is N:1, and the collectors of the at least two transistors input equal bias currents, so as to form a BE junction voltage difference when the at least two transistors operate at different current densities under equal current bias; the bandgap voltage generating circuit comprises at least one transistor, the at least one transistor utilizes the BE junction voltage difference to raise the potential of the base to form a bandgap reference voltage; wherein the emitter of the transistor outputting the BE junction voltage difference in the at least two transistors and the emitter of the transistor inputting the BE junction voltage difference in the at least one transistor are jointly provided with an emitter bias current by a first current source.

2. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The at least two transistors include a first transistor and a second transistor, the ratio of the emitter junction area of ​​the first transistor to the emitter junction area of ​​the second transistor is N:1, and the collector of the first transistor and the collector of the second transistor are biased with equal current; wherein the base and collector of the first transistor are connected to the base of the second transistor, and the BE junction voltage difference is output from the emitter of the first transistor; or, the base of the first transistor is connected to the collector of the second transistor, and the base of the second transistor is connected to the collector of the first transistor, so as to output the BE junction voltage difference from the emitter of the first transistor; And / or, the at least one transistor includes a fourth-first transistor and a fourth-second transistor, the ratio of the emitter junction area of ​​the fourth-first transistor to the emitter junction area of ​​the fourth-second transistor is 1:1, and the collector of the fourth-first transistor and the collector of the fourth-second transistor are biased with equal currents; wherein, the base of the fourth-first transistor is connected to the collector of the fourth-second transistor, the base of the fourth-second transistor is connected to the collector of the fourth-first transistor, the emitter of the fourth-first transistor is provided with an emitter current by a second current source, the emitter of the fourth-second transistor inputs the BE junction voltage difference, and the base of the fourth-second transistor is used to output the bandgap reference voltage.

3. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The at least two transistors include a first-first transistor, a first-second transistor, a first-third transistor and a first-fourth transistor, the ratio of the emitter junction area of ​​the first-first transistor to the emitter junction area of ​​the first-second transistor is N:1, and the ratio of the emitter junction area of ​​the first-third transistor to the emitter junction area of ​​the first-fourth transistor is N:1; Wherein, the base of the first transistor is connected to the collector of the first transistor and the emitter of the first transistor, the base of the first transistor is connected to the collector of the first transistor and the emitter of the first transistor, the emitter of the first transistor is grounded, the base and collector of the first transistor are connected to the base of the first transistor, the collector of the first transistor is biased with equal current, and the emitter of the first transistor is used to output the BE junction voltage difference; And / or, the at least one transistor includes a forty-first transistor, a forty-second transistor, a forty-third transistor and a forty-fourth transistor, the ratio of the emitter junction area of ​​the forty-first transistor to the emitter junction area of ​​the forty-second transistor is 1:1, the ratio of the emitter junction area of ​​the forty-third transistor to the emitter junction area of ​​the forty-fourth transistor is 1:1, and the collector of the forty-third transistor and the collector of the forty-fourth transistor are biased with equal currents; wherein, the base of the forty-first transistor is connected to the collector of the forty-second transistor and the emitter of the forty-third transistor, the base of the forty-second transistor is connected to the collector of the forty-first transistor and the emitter of the forty-fourth transistor, the base and collector of the forty-third transistor are connected to the base of the forty-fourth transistor, the emitter of the forty-first transistor is provided with an emitter current by the second current source, the emitter of the forty-second transistor inputs the BE junction voltage difference, and the base of the forty-second transistor outputs the bandgap reference voltage.

4. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The at least two transistors include a first transistor, a second transistor, a third transistor and a fourth transistor, the ratio of the emitter junction area of ​​the first transistor to the emitter junction area of ​​the second transistor is N:1, and the ratio of the emitter junction area of ​​the third transistor to the emitter junction area of ​​the fourth transistor is N:1; The base of the first transistor is connected to the collector of the second transistor and the emitter of the third transistor, the base of the second transistor is connected to the collector of the first transistor and the emitter of the fourth transistor, the emitter of the second transistor is grounded, the base and collector of the third transistor are connected to the base of the fourth transistor, the collector of the third transistor and the collector of the fourth transistor are biased with equal currents, and the emitter of the first transistor is used to output the BE junction voltage difference; And / or, the at least one transistor includes a forty-first transistor, a forty-second transistor, a forty-third transistor and a forty-fourth transistor, the ratio of the emitter junction area of ​​the forty-first transistor to the emitter junction area of ​​the forty-second transistor is 1:1, the ratio of the emitter junction area of ​​the forty-third transistor to the emitter junction area of ​​the forty-fourth transistor is 1:1, and the collector of the forty-third transistor and the collector of the forty-fourth transistor are biased with equal currents; wherein, the base of the forty-first transistor is connected to the collector of the forty-second transistor and the emitter of the forty-third transistor, the base of the forty-second transistor is connected to the collector of the forty-first transistor and the emitter of the forty-fourth transistor, the base and collector of the forty-third transistor are connected to the base of the forty-fourth transistor, the emitter of the forty-first transistor is provided with an emitter current by the second current source, the emitter of the forty-second transistor inputs the BE junction voltage difference, and the base of the forty-second transistor outputs the bandgap reference voltage.

5. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The first transistor circuit further includes a first operational amplifier and a first bias current source; wherein the first bias current source is used to provide a first bias current, the first bias current source is connected in series between a first input terminal of the first operational amplifier and a power supply terminal, and a second input terminal of the first operational amplifier is connected to an output terminal of the first operational amplifier, so as to provide equal first bias currents to collectors of the at least two transistors after the first input terminal and the second input terminal of the first operational amplifier are connected to collectors of the at least two transistors respectively; And / or, when the at least one transistor is more than one transistor, the bandgap voltage generating circuit further includes a fourth operational amplifier and a fourth bias current source; wherein the fourth bias current source is used to provide a current equal to the first bias current, the fourth bias current source is connected in series between the first input terminal and the power supply terminal of the fourth operational amplifier, and the second input terminal of the fourth operational amplifier is connected to the output terminal of the fourth operational amplifier, so as to provide an equal bias current to the collector of the at least one transistor after being connected to the collector of the at least one transistor of more than one transistors through the first input terminal and the second input terminal of the fourth operational amplifier respectively.

6. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 5, characterized in that: The circuit structure of the first operational amplifier and / or the fourth operational amplifier includes a differential operational amplifier, and the differential operational amplifier includes a PNP differential pair tube, a first current mirror, a second current mirror, a transistor current source, an RC branch and an amplifier tube; wherein the bases of the PNP differential pair tubes are respectively used as differential input terminals of the operational amplifier, the collectors of the PNP pair tubes are provided with bias current by the transistor current source, the emitters of the PNP differential pair tubes are respectively provided with emitter current by the first current mirror as a long-tail current source after passing through resistors, the RC branch is bridged between the gate and drain of the amplifier tube, the gate of the amplifier tube is connected to the collector of a transistor in the PNP differential pair tube, the source of the amplifier tube is grounded, the drain of the amplifier tube is provided with bias current by the second current mirror, and the drain of the amplifier tube serves as the output terminal of the operational amplifier.

7. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The BE junction voltage difference generating circuit also includes a second transistor circuit, and the circuit structure formed by the transistors in the second transistor circuit is the same as the circuit structure formed by the transistors in the first transistor circuit; wherein the emitter of the transistor outputting the BE junction voltage difference among the at least two transistors in the first transistor circuit is connected to the emitter of the transistor inputting the BE junction voltage difference among the at least two transistors in the second transistor circuit and the emitter current is provided by a first current source, and the emitter of the transistor outputting the BE junction voltage difference among the at least two transistors in the second transistor circuit and the emitter of the transistor for inputting the BE junction voltage difference among the at least one transistor are jointly provided with an emitter current by a second current source with a current equal to that of the first current source, so that the second transistor circuit is connected in series between the first transistor circuit and the bandgap voltage generating circuit.

8. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 7, characterized in that: The BE junction voltage difference generating circuit also includes a third transistor circuit, and the circuit structure formed by the transistors in the third transistor circuit is the same as the circuit structure formed by the transistors in the first transistor circuit; wherein the emitter of the transistor outputting the BE junction voltage difference among the at least two transistors in the second transistor circuit is connected to the emitter of the transistor inputting the BE junction voltage difference among the at least two transistors in the third transistor circuit and the emitter current is provided by a second current source, and the emitter of the transistor outputting the BE junction voltage difference among the at least two transistors in the third transistor circuit and the emitter of the transistor for inputting the BE junction voltage difference among the at least one transistor are provided with an emitter current by a third current source having a current equal to that of the first current source, so that the third transistor circuit is connected in series between the second transistor circuit and the bandgap voltage generating circuit.

9. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 1, characterized in that: The first current source includes a reference current source and a current mirror, wherein the current of the reference current source is equal to the collector current of the at least two transistors, and the reference current source is connected in series between the current mirror and a power supply terminal, and the current mirror is used to replicate the current of the reference current source to provide the emitter bias current.

10. The ultra-low low-frequency noise resistance-free bandgap reference power supply according to claim 9, characterized in that: When the current used to bias the collectors of the at least two transistors is equal to the current used to bias the collector of the at least one transistor, the current mirror includes a first current mirror transistor and a second current mirror transistor, the ratio of the emitter junction area of ​​the first current mirror transistor to the emitter junction area of ​​the second current mirror transistor is 1:2, the collector and base of the first current mirror transistor are connected to the base of the second current mirror transistor to input the current provided by the reference current source, the emitter of the first current mirror transistor and the emitter of the second current mirror transistor are grounded, and the collector of the second current mirror transistor is used to provide the emitter bias current.

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