CN112835404B

CN112835404B - Band gap reference circuit and electronic equipment

Info

Publication number: CN112835404B
Application number: CN202011622984.9A
Authority: CN
Inventors: 杨潺; 宋志军; 杜士才; 陈朝勇; 曹雷
Original assignee: Shanghai Awinic Technology Co Ltd
Current assignee: Shanghai Awinic Technology Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-07-19
Anticipated expiration: 2040-12-31
Also published as: CN112835404A

Abstract

The application discloses band gap reference circuit and electronic equipment, band gap reference circuit includes: the circuit comprises a first switch tube, a second switch tube, a first resistor, a control circuit and an operational amplification circuit, wherein the first switch tube and the second switch tube form a current mirror structure, and generate a first control voltage based on the voltage input by a voltage input end; the control circuit generates a first adjusting voltage and a second adjusting voltage based on the first control voltage, and the operational amplification circuit adjusts the control end voltage of the second switching tube based on the first adjusting voltage and the second adjusting voltage until the band-gap reference circuit establishes a normal working point and outputs a reference voltage. The band-gap reference circuit provided by the application can gradually break through a zero degeneracy point after the voltage is input at the voltage input end, enters a stable working state and outputs the reference voltage, so that self-starting is realized without an additional starting circuit.

Description

Band gap reference circuit and electronic equipment

Technical Field

The present application relates to the field of semiconductor integrated circuits, and in particular, to a bandgap reference circuit and an electronic device.

Background

With the development of semiconductor integrated circuits, power supply systems of the semiconductor integrated circuits are expanded from lithium batteries to button batteries or solar batteries. However, when a solar cell is used as a power supply to supply power, since the voltage fluctuation is large and the voltage may drop to a relatively low value, a bandgap reference circuit with low voltage, low power consumption and high power supply rejection ratio (PSR) is required to ensure the stability of the output voltage.

The basic principle of the bandgap reference circuit is to add the voltage with positive temperature coefficient and the voltage with negative temperature coefficient with proper weight to finally obtain the reference voltage with zero temperature coefficient. However, in actual operation, the bandgap reference circuit has two degeneracy points, namely 0 and reference voltage, and the conventional bandgap reference circuit needs to be additionally provided with a starting circuit to break a zero degeneracy point during starting so as to be adjusted to enter a normal operating point.

Disclosure of Invention

In order to solve the technical problem, the application provides a bandgap reference circuit and an electronic device, so that the bandgap reference circuit can realize self-starting without adding an additional starting circuit.

In order to achieve the above purpose, the present application provides the following technical solutions:

a bandgap reference circuit comprising: a first switch tube, a second switch tube, a first resistor, a control circuit and an operational amplifier circuit, wherein,

the first end of the first switch tube is connected with the voltage input end of the band-gap reference circuit, the second end of the first switch tube is grounded through the first resistor, and the control end of the first switch tube is connected with the second end of the first switch tube;

the first end of the second switching tube is connected with the voltage input end of the band-gap reference circuit, the second end of the second switching tube is the output end of the band-gap reference circuit, and the control end of the second switching tube is connected with the control end of the first switching tube;

the first end of the control circuit is connected with the second end of the second switch tube, the second end of the control circuit is grounded, the third end of the control circuit is connected with the first input end of the operational amplification circuit, the fourth end of the control circuit is connected with the second input end of the operational amplification circuit, and the output end of the operational amplification circuit is connected with the control end of the second switch tube;

the first switching tube and the second switching tube form a current mirror structure, and a first control voltage is generated based on the voltage input by the voltage input end; the control circuit generates a first regulation voltage and a second regulation voltage based on the first control voltage, and the operational amplification circuit regulates the control end voltage of the second switching tube based on the first regulation voltage and the second regulation voltage until the band-gap reference circuit outputs a reference voltage.

Optionally, the control circuit generates a first regulated voltage to be output through a third terminal thereof and simultaneously generates a second regulated voltage to be output through a fourth terminal thereof based on the first control voltage input through the first terminal thereof; the operational amplification circuit adjusts the voltage of the control end of the second switching tube based on the first adjusting voltage input by the first input end and the second adjusting voltage input by the second input end until the band-gap reference circuit outputs the reference voltage.

Optionally, the control circuit includes: the first branch, the second branch and the third branch are electrically connected between the second end of the second switching tube and the ground end;

the first end of the first branch circuit is connected with the second end of the second switching tube, the second end of the first branch circuit is grounded, and the first branch circuit is used for generating a second control voltage based on the first control voltage input by the first end of the first branch circuit and outputting the second control voltage to the control end of the second branch circuit through the output end of the second branch circuit;

the first end of the second branch circuit is connected with the second end of the second switching tube, the second end of the second branch circuit is grounded, and the second branch circuit is used for generating the first regulating voltage based on the first control voltage input by the first end of the second branch circuit and the second control voltage input by the control end of the second branch circuit, outputting the first regulating voltage to the first input end of the operational amplification circuit through the first output end of the first regulating voltage, and generating the third control voltage and outputting the third control voltage to the control end of the third branch circuit through the second output end of the third regulating voltage;

the first end of the third branch circuit is connected with the second end of the second switching tube, the second end of the third branch circuit is grounded, and the third branch circuit is used for generating a second adjusting voltage based on the first control voltage input by the first end of the third branch circuit and the third control voltage input by the control end of the third branch circuit and outputting the second adjusting voltage to the second input end of the operational amplification circuit through the output end of the operational amplification circuit, so that the operational amplification circuit adjusts the voltage at the control end of the second switching tube based on the first adjusting voltage and the second adjusting voltage until the band-gap reference circuit outputs the reference voltage.

Optionally, in the control circuit,

the first branch includes:

the first end of the second resistor is connected with the second end of the second switching tube, the second end of the second resistor is connected with the first end of the first triode, the second end of the first triode is grounded, and the control end of the first triode is connected with the first end of the first triode;

the second branch circuit includes:

the first end of the third resistor is connected with the second end of the second switching tube, the second end of the third resistor is connected with the first end of the second triode, the second end of the second triode is grounded through the fourth resistor, and the control end of the second triode is connected with the control end of the first triode;

the third branch includes:

the first end of the fifth resistor is connected with the second end of the second switching tube, the second end of the fifth resistor is connected with the first end of the third triode, the second end of the third triode is grounded, and the control end of the third triode is connected with the first end of the second triode;

the first end of the second triode is connected with the first input end of the operational amplification circuit and outputs the first regulating voltage; the first end of the third triode is connected with the second input end of the operational amplification circuit and outputs the second regulating voltage;

the second resistor, the third resistor and the fifth resistor are equal in resistance value.

Optionally, the bandgap reference circuit further includes:

and the sixth resistor is positioned between the voltage input end and the first end of the first switching tube, the first end of the sixth resistor is connected with the voltage input end, and the second end of the sixth resistor is connected with the first end of the first switching tube.

Optionally, the operational amplifier circuit includes: an operational amplifier, a seventh resistor, and a first capacitor, wherein,

the first input end of the operational amplifier is connected with the first end of the second triode, the second input end of the operational amplifier is connected with the first end of the third triode, the output end of the operational amplifier is connected with the control end of the second switching tube,

the output end of the operational amplifier is also grounded through the seventh resistor and the first capacitor which are connected in series.

Optionally, the operational amplifier further has a power input end, and the power input end of the operational amplifier is connected to the second end of the second switch tube.

Optionally, the first input end of the operational amplifier is a positive input end of the operational amplifier, and the second input end of the operational amplifier is a negative input end of the operational amplifier.

Optionally, the first input end of the operational amplifier is a negative input end of the operational amplifier, the second input end of the operational amplifier is a positive input end of the operational amplifier, and the operational amplifier circuit further includes:

and the third switching tube is positioned between the second end of the second switching tube and the end, far away from the first resistor, of the first switching tube, the first end of the third switching tube is connected with the second end of the second switching tube, the second end of the third switching tube is connected with the end, far away from the first resistor, of the first switching tube, and the control end of the third switching tube is connected with the output end of the operational amplifier.

Optionally, the operational amplifier circuit further includes:

and the fourth switching tube is positioned between the second end of the first switching tube and the end, far away from the first resistor, of the first switching tube, the first end of the fourth switching tube is connected with the second end of the first switching tube, the second end of the fourth switching tube is connected with the end, far away from the first resistor, of the first switching tube, and the control end of the fourth switching tube is connected with the bias voltage input end.

Optionally, the bandgap reference circuit further includes:

and the first end of the second capacitor is connected with the first end of the fourth switch tube, and the second end of the second capacitor is connected with the second end of the fourth switch tube.

Optionally, the bandgap reference circuit further includes:

and the first end of the third capacitor is connected with the second end of the second switching tube, and the second end of the third capacitor is connected with the second input end of the operational amplification circuit.

An electronic device comprising a bandgap reference circuit as claimed in any preceding claim.

Compared with the prior art, the technical scheme has the following advantages:

the band gap reference circuit provided by the embodiment of the application comprises a first switching tube, a second switching tube, a first resistor, a control circuit and an operational amplification circuit, wherein the first switching tube and the second switching tube form a current mirror structure, and a first control voltage is generated based on a voltage input by a voltage input end; the control circuit generates a first regulation voltage and a second regulation voltage based on the first control voltage, and the operational amplification circuit regulates the control end voltage of the second switching tube based on the first regulation voltage and the second regulation voltage until the band-gap reference circuit establishes a normal working point and outputs a reference voltage. Therefore, the bandgap reference circuit provided by the embodiment of the application can gradually break through a zero degeneracy point after the voltage is input at the voltage input end, enter a stable working state and output the reference voltage, so that self-starting is realized without an additional starting circuit.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic circuit diagram of a bandgap reference circuit and a start-up circuit thereof;

FIG. 2 is a schematic diagram of a bandgap reference circuit according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a bandgap reference circuit according to another embodiment of the present application;

FIG. 4 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 5 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 6 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 7 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 8 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 9 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

FIG. 10 is a schematic diagram of a bandgap reference circuit according to yet another embodiment of the present application;

fig. 11 is a schematic diagram of a small-signal equivalent circuit of the fourth switching transistor M4 in the bandgap reference circuit shown in fig. 10;

fig. 12 is a schematic diagram of a bandgap reference circuit according to still another embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways than those described herein, and it will be apparent to those of ordinary skill in the art that the present application is not limited to the specific embodiments disclosed below.

Next, the present application will be described in detail with reference to the drawings, and in the detailed description of the embodiments of the present application, the cross-sectional views illustrating the device structures are not enlarged partially in general scale for the sake of illustration, and the drawings are only examples, which should not limit the scope of protection of the present application. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

As described in the background section, the conventional bandgap reference circuit needs to add an additional start-up circuit to break the zero degeneracy point at the start-up.

Fig. 1 shows a circuit structure schematic diagram of a bandgap reference circuit and a start-up circuit thereof, as shown in fig. 1, the bandgap reference circuit includes an operational amplifier OPA, three PMOS transistors M10, M20 and M30, two PNP-type triodes Q10 and Q20, and four resistors R00, R10, R20 and R30, the start-up circuit includes a depletion-type NMOS transistor MS, and a control terminal of the start-up circuit is connected to an output terminal of the bandgap reference circuit. Specifically, when the power supply voltage VDD starts to be powered on, the output voltage of the bandgap reference circuit is 0V, that is, the voltage of the OUT terminal in fig. 1 is 0V, and the voltage at the connection point a is 0V, because the threshold voltage of the depletion NMOS transistor MS is a negative value, the gate-source voltage of the NMOS transistor MS is greater than the threshold voltage thereof at this time, the NMOS transistor MS is turned on, and the power supply voltage VDD starts to charge the connection point a; when the voltage of the connection point A is larger than the output voltage of the band-gap reference circuit, the NMOS tube MS is turned off, the band-gap reference circuit breaks a zero degeneracy point, and normal work is started.

In addition, after a normal operating point is established, the conventional bandgap reference circuit needs to turn off the start-up circuit, otherwise, the bias of the reference voltage is caused. The following description is continued with the circuit configuration shown in fig. 1, in which the collector current I of the transistor Q10 is set in the bandgap reference circuit_C10Comprises the following steps:

I_C10＝I_S10exp(V_BE10/V_T) (1)

wherein, I_S10Is the saturation current, V, of transistor Q10_BE10Is the emitter-base voltage, V, of transistor Q10_TkT/q is a thermal voltage, K is boltzmann's constant, q is an electron charge amount, T is a thermodynamic temperature, and V is at room temperature (T300K)_T≈0.026eV。

Therefore, the emitter-base voltage V of the transistor Q10_BE10Comprises the following steps:

V_BE10＝V_Tln(I_C10/I_S10) (2)

further, the difference between the emitter-base voltages of the transistors Q10 and Q20 is:

wherein, I_S20Is the saturation current, I, of transistor Q20_C20Is the collector current of transistor Q20.

Since the PMOS transistors M10 and M20 in FIG. 1 form a current mirror structure, the currents flowing through the PMOS transistors M10 and M20 are equal, i.e., I₁₀＝I₂₀And I is_C10＝I₁₀，I_C20＝I₂₀-I_R20Wherein, I_R20The current flowing through resistor R20, therefore, the difference between the emitter-base voltages of transistors Q10 and Q20 is:

after the bandgap reference circuit establishes a normal operating point, if the NMOS transistor MS of the start-up circuit is not turned off, the voltage of the connection point a is still less than the output voltage of the bandgap reference circuit, and then the source of the NMOS transistor MS will continue to inject current into the connection point a, so that the current I of the PMOS transistor M10₁₀Current I less than M20₂₀In combination with equation (4), it can be seen that if the current I of PMOS transistor M10 is increased₁₀Current I less than M20₂₀Will make Δ V_BE0A certain deviation occurs, eventually causing the reference voltage to shift. In addition, in order to close the starting circuit after the bandgap reference circuit enters a normal working point, a depletion type NMOS transistor MS is adopted, and other MOS transistors in the bandgap reference circuit are enhancement type MOS transistors.

In view of this, the embodiments of the present application provide a bandgap reference circuit, which can implement self-starting without adding an additional starting circuit.

Fig. 2 is a bandgap reference circuit according to an embodiment of the present application, and as shown in fig. 2, the bandgap reference circuit includes:

a first switch tube M1, a second switch tube M2, a first resistor R1, a control circuit 100 and an operational amplifier circuit 200, wherein,

a first end of the first switch tube M1 is connected with a voltage input end of the bandgap reference circuit, a power supply voltage VDD is input, a second end is grounded through the first resistor R1, and a control end is connected with the second end;

a first end of the second switch tube M2 is connected to a voltage input end of the bandgap reference circuit, a second end is an output end of the bandgap reference circuit, and outputs a reference voltage Vout, and a control end is connected to a control end of the first switch tube M1;

the first end of the control circuit 100 is connected to the second end of the second switch tube M2, the second end is grounded, the third end is connected to the first input end of the operational amplifier circuit 200, the fourth end is connected to the second input end of the operational amplifier circuit 200, and the output end of the operational amplifier circuit 200 is connected to the control end of the second switch tube M2;

the first switch tube M1 and the second switch tube M2 form a current mirror structure, generate a first control voltage based on the voltage VDD input by the voltage input terminal, and output the first control voltage to the first terminal of the control circuit 100; the control circuit 100 generates a first regulation voltage and a second regulation voltage based on the first control voltage; the operational amplifier circuit 200 adjusts the voltage at the control end of the second switching tube M2 based on the first adjusting voltage V1 and the second adjusting voltage V2 until the bandgap reference circuit establishes a normal operating point, and outputs a reference voltage Vout.

Optionally, in an embodiment of the present application, the first switch tube and the second switch tube are both first type field effect transistors, and optionally, the first type field effect transistor is a P type field effect transistor, that is, a PMOS transistor, but the present application does not limit this, which is determined as the case may be.

The self-starting process of the bandgap reference circuit is described below by taking the first switch transistor M1 and the second switch transistor M2 as PMOS transistors as an example, at this time, the first ends of the two switch transistors are both source electrodes, the second ends thereof are both drain electrodes, and the control ends thereof are both gate electrodes.

Specifically, when the voltage VDD input by the voltage input terminal is powered up from 0V, the voltage value of the voltage VDD is smaller than the on-state voltage drop of the first switching tube M1, the first switching tube M1 and the second switching tube M2 are both in an off state, at this time, the voltage V1 input by the first input terminal of the operational amplifier circuit 100 is equal to the voltage V2 input by the second input terminal thereof, and is 0V, that is, V1 is equal to V2 is equal to 0V.

When the voltage VDD input by the voltage input terminal is greater than the conduction voltage drop of the first switch tube M1, as the voltage VDD input by the voltage input terminal continues to increase, a path formed by the first switch tube M1 and the first resistor R1 to ground begins to conduct slowly, and the current flowing through the first switch tube M1 begins to increase. Since the first switch transistor M1 and the second switch transistor M2 form a current mirror structure, and since the control circuit 100 is still in the off state at this time, it can be equivalent to a capacitor, the second switch transistor M2 starts to mirror the current flowing through the first switch transistor M1, so as to charge the equivalent capacitor of the control circuit 100 through the second terminal thereof, and further generate the first control voltage at the second terminal thereof to output to the first terminal of the control circuit 100.

As the voltage VDD input by the voltage input terminal continues to increase, the current flowing through the first switching tube M1 gradually increases, the current flowing through the second switching tube M2 also gradually increases, so that the voltage at the second end of the second switching tube M2 gradually increases, so that the first control voltage gradually increases, and the control circuit 100 starts to operate, at this time, the control circuit 100 generates the first adjustment voltage V1 and the second adjustment voltage V2 based on the first control voltage input by the first end thereof, so that the bandgap reference circuit breaks through a zero degenerate point, and thus self-start is achieved; further, the operational amplifier circuit 200 adjusts the control terminal voltage of the second switching tube M2 based on the first adjustment voltage V1 and the second adjustment voltage V2 until the bandgap reference circuit establishes a normal operating point, and outputs a reference voltage Vout.

Therefore, the bandgap reference circuit provided by the embodiment of the application can break a zero degeneracy point and realize self-starting without additionally adding a starting circuit.

Alternatively, on the basis of the above embodiments, in an embodiment of the present application, as shown in fig. 2, the control circuit 100 generates the first regulated voltage V1 to be output through the third terminal thereof, and simultaneously generates the second regulated voltage V2 to be output through the fourth terminal thereof, based on the first control voltage input through the first terminal thereof; the operational amplifier circuit 200 regulates the control terminal voltage of the second switching transistor M2 based on the first regulating voltage V1 input at the first input terminal and the second regulating voltage V2 input at the second input terminal thereof until the bandgap reference circuit establishes a normal operating point, and outputs a reference voltage Vout.

On the basis of the above-mentioned embodiments, in an embodiment of the present application, as shown in fig. 3, the control circuit 100 includes: a first branch 10, a second branch 20 and a third branch 30 electrically connected between the second end of the second switch tube and the ground end;

the first end of the first branch 10 is connected to the second end of the second switching tube M2, and the second end is grounded, so as to generate a second control voltage based on the first control voltage input by the first end, and output the second control voltage to the control end of the second branch 20 through the output end of the second branch;

the first end of the second branch 20 is connected to the second end of the second switch M2, the second end is grounded, and the second branch is configured to generate the first regulated voltage V1 based on the first control voltage input from the first end and the second control voltage input from the control end, and output the first regulated voltage V1 to the first input end of the operational amplifier circuit 200 through the first output end thereof, and generate the third control voltage and output the third control voltage to the control end of the third branch 30 through the second output end thereof;

the first end of the third branch 30 is connected to the second end of the second switching tube M2, and the second end is grounded, so that the second regulated voltage V2 is generated based on the first control voltage input from the first end and the third control voltage input from the control end, and is output to the second input end of the operational amplifier circuit 200 through the output end, so that the operational amplifier circuit 200 regulates the control end voltage of the second switching tube M2 based on the first regulated voltage V1 and the second regulated voltage V2 until the bandgap reference circuit establishes a normal operating point, and outputs the reference voltage Vout.

It should be noted that, in the embodiment of the present application, after the voltage VDD input at the voltage input terminal is greater than the conduction voltage drop of the first switching tube M1, the second switching tube M2 generates the first control voltage at the second terminal thereof and outputs the first control voltage to the first terminal of the first branch 10, the first terminal of the second branch 20, and the first terminal of the third branch 30 in the control circuit 100. As the voltage VDD input by the voltage input terminal increases, the first control voltage generated by the second switch tube M2 at the second terminal thereof gradually increases, so that the control circuit 100 starts to operate.

At this time, in the control circuit 100, as shown in fig. 3, the first branch circuit 10 generates the second control voltage based on the first control voltage input at the first end thereof, and outputs the second control voltage to the control end of the second branch circuit 20 through the output end thereof; the second branch circuit 20 generates the first regulated voltage V1 to be output to the first input terminal of the operational amplifier circuit 200 through the first output terminal thereof and generates the third control voltage to be output to the control terminal of the third branch circuit 30 through the second output terminal thereof based on the first control voltage input to the first terminal thereof and the second control voltage input to the control terminal thereof; the third branch circuit 30 generates the second adjustment voltage V2 based on the first control voltage input from the first terminal and the third control voltage input from the control terminal, and outputs the second adjustment voltage V2 to the second input terminal of the operational amplifier circuit 200 through the output terminal thereof, and the bandgap reference circuit breaks a zero degeneracy point, thereby realizing self-starting.

Further, the operational amplifier circuit 200 adjusts the control terminal voltage of the second switching transistor M2 based on the first adjusting voltage V1 inputted from the first input terminal thereof and the second adjusting voltage V2 inputted from the second input terminal thereof, so as to adjust the second terminal voltage of the second switching transistor M2 until the bandgap reference circuit establishes a normal operating point, and output the reference voltage Vout at the second terminal of the second switching transistor M2.

On the basis of the above-described embodiment, in one embodiment of the present application, as shown in fig. 4,

the first branch 10 includes:

a second resistor R2 and a first triode Q1 which are connected in series, wherein a first end of the second resistor R2 is connected to a second end of the second switching tube M2, a second end of the second resistor R2 is connected to a first end of the first triode Q1, a second end of the first triode Q2 is grounded, and a control end of the first triode Q2 is connected to the first end of the first triode;

the second branch 20 includes:

a third resistor R3, a second triode Q2 and a fourth resistor R4 which are connected in series, wherein a first end of the third resistor R3 is connected to a second end of the second switching tube M2, a second end of the third resistor R3 is connected to a first end of the second triode Q2, a second end of the second triode Q2 is grounded through the fourth resistor R4, and a control end of the second triode Q2 is connected to a control end of the first triode Q1;

the third branch 30 includes:

a fifth resistor R5 and a third transistor Q3 connected in series, wherein a first end of the fifth resistor R5 is connected to a second end of the second switching tube M2, a second end of the fifth resistor R5 is connected to a first end of the third transistor Q3, a second end of the third transistor Q3 is grounded, and a control end of the third transistor Q3 is connected to the first end of the second transistor Q2;

a first end of the second triode Q2 is connected to a first input end of the operational amplifier circuit 200, and outputs the first regulated voltage V1; a first end of the third triode Q3 is connected to the second input end of the operational amplifier circuit 200, and outputs the second regulated voltage V2;

the resistance values of the second resistor R2, the third resistor R3 and the fifth resistor R5 are equal.

It should be noted that, in the embodiment of the present application, the first end of the first branch 10 is a first end of the second resistor, the second end is a second end of the first transistor Q1, and the output end is a control end of the first transistor Q1; the first end of the second branch 20 is the first end of the third resistor R3, the second end is the grounded end of the fourth resistor R4, the control end is the control end of the second triode Q2, and the first output end and the second output end are the same output end, which is the first end of the second triode Q2; the first end of the third branch 30 is the first end of the fifth resistor R5, the second end is the second end of the third transistor Q3, the control end is the control end of the third transistor Q3, and the output end is the first end of the third transistor Q3.

Optionally, in an embodiment of the application, the first transistor Q1, the second transistor Q2, and the third transistor Q3 are all first type transistors, and the first type transistors may be NPN type transistors or PNP type transistors.

Optionally, in an embodiment of the present application, the conduction voltage drops of the first transistor Q1, the second transistor Q2, and the third transistor Q3 are the same, which is not limited in the present application, and are determined as the case may be.

The working process of the control circuit 100 will be described below by taking as an example that the first transistor Q1, the second transistor Q2, and the third transistor Q3 are all NPN transistors, and their conduction voltage drops are the same, at this time, the first end of each transistor is a collector, the second end is an emitter, and the control end is a base.

Specifically, after the voltage VDD input by the voltage input terminal is greater than the turn-on voltage drop of the first switch tube M1, the first control voltage generated by the second switch tube M2 at the second end thereof gradually increases as the voltage VDD input by the voltage input terminal increases.

When the first control voltage is less than the conduction voltage drop of the first transistor Q1, the first transistor Q1, the second transistor Q2 and the third transistor Q3 are all not turned on, at this time, the first input terminal of the operational amplifier circuit 200 is connected to the second terminal of the second switch tube M2 through the third resistor R3, and the second input terminal of the operational amplifier circuit 200 is connected to the second terminal of the second switch tube M2 through the fifth resistor R5, so that the voltage V1 input to the first input terminal of the operational amplifier circuit 200 is equal to the voltage V2 input to the second input terminal thereof, and all of them increase with the increase of the first control voltage, i.e., all of them gradually increase from 0V.

When the first control voltage is greater than the conduction voltage drop of the first transistor Q1, the first transistor Q1 starts conducting. Since the second end of the second transistor Q2 is connected in series with the fourth resistor R4, although the second transistor Q2 also starts to conduct, the voltage between the control end and the second end thereof is smaller than the voltage between the control end and the second end of the first transistor Q1, and the first transistor Q1 starts to conduct, and the current IQ1 flowing through the first transistor Q1 is small, so the current IQ2 flowing through the second transistor Q2 is smaller, and the second transistor Q2 is still close to the off state, at this time, the voltage V1 input to the first input end of the operational amplifier circuit 200 continues to increase with the increase of the first control voltage. Since the control terminal of the third transistor Q3 is connected to the first terminal of the second transistor Q2, and also connected to the second terminal of the second switching transistor M2 through the third resistor R3, that is, the control terminal voltage of the third transistor Q3 is also greater than its conduction voltage drop, and continues to increase with the increase of the first control voltage, the third transistor Q3 also starts to conduct, at this time, since the third transistor Q3 is turned on, a current IQ3 flows through the fifth resistor R5 and the third transistor Q3, so that there is a voltage drop across the fifth resistor R5, and therefore, a voltage V2 input at the second input terminal of the operational amplifier circuit appears a steep drop, so that the voltage V1 input at the first input terminal of the operational amplifier circuit 200 is greater than the voltage V2 input at the second input terminal thereof, that is V1> V2, but at this time, since the voltage input terminal is smaller, the first control voltage generated by the second switch M2 at the second end thereof is also relatively small, which just causes the first transistor Q1 and the third transistor Q3 to start conducting, so that the voltage V1 input at the first input end of the operational amplifier circuit 200 and the voltage V2 input at the second input end thereof are still relatively small, which is not enough to cause the operational amplifier circuit 200 to start operating.

As the voltage VDD inputted from the voltage input terminal continues to increase, the first control voltage generated by the second switching transistor M2 at the second terminal thereof also continues to increase, so that the control terminal voltage of the first transistor Q1 gradually increases, and thus the control terminal voltage of the second transistor Q2 also gradually increases, and further the second transistor Q2 gradually conducts, at this time, the current IQ2 flowing through the second transistor Q2 gradually increases, and the voltage drop across the third resistor R3 connected in series with the second transistor Q2 gradually increases, so that the voltage V1 inputted from the first input terminal of the operational amplifier circuit 200 also has a steep drop at this time, that is, the control terminal voltage of the third transistor Q3 also has a steep drop, so that the current IQ3 flowing through the third transistor Q3 decreases, and the voltage drop across the fifth resistor R5 connected in series with the third transistor Q3 decreases, further, the voltage V2 input at the second input terminal of the operational amplifier circuit 200 will have a jump, and since the third transistor Q3 is just turned on, the current IQ3 flowing through the third transistor Q3 is inherently small, at this time, the steep drop of the control terminal voltage of the third transistor Q3 makes the current IQ3 flowing through the third transistor Q3 become smaller than the current IQ2 flowing through the second transistor Q2, so that the voltage drop across the fifth resistor R5 is smaller than the voltage drop across the third resistor R3, and further the voltage V1 input at the first input terminal of the operational amplifier circuit 200 is smaller than the voltage V2 input at the second input terminal thereof, i.e., V1< V2, and at this time, the voltage VDD input at the voltage input terminal is already large, the first control voltage generated at the second terminal of the second switching tube M2 is already large, so that the first transistor Q1, the current IQ3 flowing through the third transistor Q3538 is already turned on, Both the second transistor Q2 and the third transistor Q3 are turned on, so that the operational amplifier circuit 200 can start operating already by the voltage V1 inputted to the first input terminal of the operational amplifier circuit 200 and the voltage V2 inputted to the second input terminal thereof.

It should be noted that the voltage signal output from the output terminal of the operational amplifier circuit 200 is determined based on the magnitudes of the voltage V1 input from the first input terminal and the voltage V2 input from the second input terminal, that is, when the voltage V1 input from the first input terminal of the operational amplifier circuit is greater than the voltage V2 input from the second input terminal thereof, the voltage output from the output terminal thereof increases; when the voltage V1 input by the first input end of the operational amplification circuit is smaller than the voltage V2 input by the second input end of the operational amplification circuit, the voltage output by the output end of the operational amplification circuit is reduced. Therefore, when the second transistor Q2 is turned on, and the voltage V1 input at the first input terminal of the operational amplifier circuit is smaller than the voltage V2 input at the second input terminal thereof, the voltage output at the output terminal of the operational amplifier circuit decreases, and the voltage at the control terminal of the second switching tube M2 is pulled low, so that the voltage between the control terminal of the second switching tube M2 and the first terminal thereof increases, and thus the current flowing through the second switching tube M2 increases, and the voltage at the second terminal of the second switching tube M2 increases, that is, the first control voltage continues to increase.

After the second transistor Q2 is turned on, the current IQ2 flowing through the second transistor Q2 is:

wherein, Δ V_BEThe difference between the voltage between the control terminal of the first transistor Q1 and the second terminal thereof and the voltage between the control terminal of the second transistor Q2 and the second terminal thereof is, therefore, when the second transistor Q2 is turned on, as the first control voltage continues to increase, the voltage between the control terminal of the first transistor Q1 and the second terminal thereof and the voltage between the control terminal of the second transistor Q2 and the second terminal thereof change synchronously, so that the difference Δ V between the voltage between the control terminal of the first transistor Q1 and the second terminal thereof and the voltage between the control terminal of the second transistor Q2 and the second terminal thereof is_BEThe variation is small.

As can be seen from equation (5), the difference Δ V between the voltage between the control terminal of the first transistor Q1 and the second terminal thereof and the voltage between the control terminal of the second transistor Q2 and the second terminal thereof_BEThe small variation causes the current IQ2 flowing through the second transistor Q2 to vary little, thereby causing the third resistor in series with the second transistor Q2The pressure drop across R3 varies little. Therefore, as the first control voltage continues to increase, the voltage V1 input to the first input terminal of the operational amplifier circuit 200 continues to increase, that is, the control terminal voltage of the third transistor Q3 continues to increase, so that the current IQ3 flowing through the third transistor Q3 gradually increases, so that the voltage drop across the fifth resistor R5 connected in series with the third transistor Q3 gradually increases, and the voltage V2 input to the second input terminal of the operational amplifier circuit 200 gradually decreases until the voltage V1 input to the first input terminal of the operational amplifier circuit 200 is equal to the voltage V2 input to the second input terminal thereof, and the bandgap reference circuit establishes a normal operating point, and outputs the reference voltage Vout at the second terminal of the second switch M2.

Specifically, the reference voltage Vout output by the second end of the second switch tube M2 is:

wherein, V_BE(Q3) is the voltage between the control terminal of the third transistor Q3 and the second terminal thereof, and has a negative temperature coefficient, Δ V_BEThe difference between the voltage of the control terminal of the first transistor Q1 and the second terminal thereof and the voltage of the control terminal of the second transistor Q2 and the second terminal thereof has a positive temperature coefficient. As can be seen from equation (6), by appropriately selecting the resistances of the third resistor R3 and the fourth resistor R4, the reference voltage Vout with zero temperature coefficient can be obtained.

As can be seen from the above, in the embodiment of the present application, after the voltage VDD input by the voltage input terminal is greater than the turn-on voltage drop of the first switch tube M1, as the voltage VDD input by the voltage input terminal increases, the first control voltage generated by the second switch tube M2 at the second end thereof gradually increases, so that the voltage V1 input by the first input terminal of the operational amplifier circuit 200 and the voltage V2 input by the second input terminal thereof gradually increase from 0V; when the first triode Q1 and the third triode Q3 are turned on, the voltage V2 input by the second input terminal of the operational amplifier circuit appears a steep drop, and at this time, the voltage V1 input by the first input terminal of the operational amplifier circuit is greater than the voltage V2 input by the second input terminal thereof; when the second transistor Q2 is turned on, the voltage V1 input by the first input terminal of the operational amplifier circuit also appears a steep drop, and the voltage V2 input by the second input terminal thereof appears a jump, at this time, the voltage V1 input by the first input terminal of the operational amplifier circuit is less than the voltage V2 input by the second input terminal thereof, so that the voltage output by the output terminal of the operational amplifier circuit decreases, and the voltage at the control terminal of the second switching tube M2 is pulled low, therefore, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof increases, the current flowing through the second switching tube M2 increases, so that the first control voltage generated by the second switching tube M2 at the second terminal thereof continues to increase, and the voltage V1 input by the first input terminal of the operational amplifier circuit continues to increase, and the voltage V2 input by the second input terminal thereof gradually decreases, until the voltage V1 input by the first input terminal of the operational amplifier circuit 200 is equal to the voltage V2 input by the second input terminal thereof, the bandgap reference circuit establishes a normal operating point, and outputs the reference voltage Vout at the second terminal of the second switch transistor M2.

It should be noted that, in this embodiment of the application, the output terminal of the operational amplifier circuit 200 is connected to the control terminal of the second switching tube M2, and when the voltage VDD input by the voltage input terminal of the bandgap reference circuit fluctuates and the reference voltage Vout thereof changes, the operational amplifier circuit 100 may control the voltage of the output terminal to change in the same direction based on the magnitude of the voltage V1 input by the first input terminal and the voltage V2 input by the second input terminal thereof, so that the voltage of the control terminal of the second switching tube M2 changes in the same direction, so that the voltage between the control terminal of the second switching tube M2 and the first terminal thereof changes in the opposite direction, and the voltage of the second terminal of the second switching tube Q2 changes in the opposite direction, that is, the reference voltage Vout changes in the opposite direction, until the reference voltage Vout is kept stable.

Next, the adjustment process of the operational amplifier circuit 200 will be described by taking the first switch transistor M1 and the second switch transistor M2 as PMOS transistors as an example.

Specifically, when the voltage VDD input by the voltage input terminal increases, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof increases, the current flowing through the second switching tube M2 increases, so that the voltage at the second terminal of the second switching tube M2 increases, that is, the reference voltage Vout increases, since the fourth resistor R4 is connected in series to the second terminal of the second transistor Q2, and the resistances of the third resistor R3 and the fifth resistor R5 are equal, the resistance of the second branch composed of the third resistor R3, the second transistor Q2 and the fourth resistor R4 is greater than the resistance of the third branch composed of the fifth resistor R5 and the third transistor Q3, so that the magnitude of the increase of the current IQ2 of the second branch is smaller than the magnitude of the increase of the current IQ3 of the third branch, and the magnitude of the voltage drop resistor IQ 5 of the third resistor R3 increases, further, the voltage V1 input at the first input terminal of the operational amplifier circuit 200 is greater than the voltage V2 input at the second input terminal thereof, at this time, the voltage output at the output terminal of the operational amplifier circuit increases, the voltage at the control terminal of the second switching tube M2 is pulled high, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof decreases, the current flowing through the second switching tube M2 decreases, the voltage at the second terminal of the second switching tube M2 decreases, and the reference voltage Vout is pulled low until the reference voltage Vout keeps stable.

When the voltage VDD inputted from the voltage input terminal is decreased, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof is decreased, the current flowing through the second switching tube M2 is decreased, so that the voltage at the second terminal of the second switching tube M2 is decreased, that is, the reference voltage Vout is decreased, and also because the resistance of the second branch composed of the third resistor R3, the second transistor Q2 and the fourth resistor R4 is greater than the resistance of the third branch composed of the fifth resistor R5 and the third transistor Q3, the magnitude of the decrease of the current IQ2 of the second branch is less than the magnitude of the decrease of the current IQ3 of the third branch, so that the magnitude of the decrease of the voltage drop across the third resistor R3 is less than the magnitude of the voltage drop across the fifth resistor R5, and further the voltage V1 inputted from the first input terminal of the operational amplifier circuit 200 is less than the voltage V2 inputted from the second input terminal thereof, at this time, the voltage output by the output end of the operational amplifier circuit decreases, and the voltage at the control end of the second switching tube M2 is pulled low, so that the voltage between the control end of the second switching tube M2 and the first end thereof increases, and the current flowing through the second switching tube M2 increases, and further the voltage at the second end of the second switching tube M2 increases, and the reference voltage Vout is pulled high until the reference voltage Vout keeps stable.

Optionally, on the basis of the foregoing embodiment, in an embodiment of the present application, as shown in fig. 5, the bandgap reference circuit further includes:

a sixth resistor R6, the sixth resistor R6 is located between the voltage input end and the first end of the first switching tube M1, the first end of the sixth resistor R8932 is connected to the voltage input end, and the second end of the sixth resistor R6 is connected to the first end of the first switching tube M1, so that in the current mirror structure formed by the first switching tube M1 and the second switching tube M2, the current flowing through the second switching tube M2 can be greater than the current flowing through the first switching tube M1 by adjusting the resistance of the sixth resistor R6, thereby ensuring the normal operation of the control circuit 100.

On the basis of the above embodiments, in an embodiment of the present application, as shown in fig. 6, the operational amplifier circuit 200 includes: an operational amplifier A1, a seventh resistor R7, and a first capacitor C1, wherein,

a first input end of the operational amplifier A1 is connected to a first end of the second transistor Q2, a second input end is connected to a first end of the third transistor Q3, an output end is connected to a control end of the second switch tube M2,

the output terminal of the operational amplifier a1 is also connected to ground through the seventh resistor R7 and the first capacitor C1 in series.

In the embodiment of the present application, the first input terminal of the operational amplifier circuit 200 is the first input terminal of the operational amplifier a1, the second input terminal of the operational amplifier circuit 200 is the second input terminal of the operational amplifier a1, and the output terminal of the operational amplifier circuit 200 is the output terminal of the operational amplifier a 1.

Optionally, on the basis of the foregoing embodiment, in an embodiment of the present application, as shown in fig. 6, the first input terminal of the operational amplifier a1 is the positive input terminal of the operational amplifier a1, the second input terminal of the operational amplifier a1 is the negative input terminal of the operational amplifier a1, that is, the positive input terminal of the operational amplifier a1 is connected to the first terminal of the second transistor Q2, the negative input terminal of the operational amplifier a1 is connected to the first terminal of the third transistor Q3, and the voltage output by the output terminal of the operational amplifier a1 is determined based on the magnitudes of the voltage V1 input by the positive input terminal and the voltage V2 input by the negative input terminal. Specifically, when the voltage V1 input to the positive input terminal of the operational amplifier a1 is greater than the voltage V2 input to the negative input terminal thereof, the voltage output from the output terminal of the operational amplifier a1 increases; when the voltage V1 input to the positive input terminal of the operational amplifier a1 is less than the voltage V2 input to the negative input terminal thereof, the voltage output from the output terminal of the operational amplifier a1 decreases.

It should be further noted that, in the embodiment of the present application, the output end of the operational amplifier a1 is connected to the control end of the second switch tube M2, so that when the voltage VDD input by the voltage input end fluctuates, so that the reference voltage Vout changes, the operational amplifier a1 controls the voltage at the output end of the operational amplifier a1 to change in the same direction based on the magnitude of the voltage V1 input by the positive input end and the voltage V2 input by the negative input end, that is, when the voltage VDD input by the voltage input end increases, so that the voltage at the output end of the operational amplifier a1 increases, the voltage V1 at the positive input end of the operational amplifier a1 is greater than the voltage V2 at the negative input end thereof, so that the voltage at the output end of the operational amplifier a1 increases; when the voltage VDD inputted from the voltage input terminal decreases to decrease the reference voltage Vout, the voltage V1 at the positive input terminal of the first operational amplifier a1 is smaller than the voltage V2 at the negative input terminal thereof, so that the voltage at the output terminal of the operational amplifier a1 decreases, and further, the voltage at the control terminal of the second switch tube M2 varies in the same direction based on the voltage at the output terminal of the operational amplifier a1, so that the voltage between the control terminal of the second switch tube M2 and the first terminal thereof varies in the opposite direction, and further the voltage at the second terminal of the second switch tube Q2 varies in the opposite direction, that is, the reference voltage Vout varies in the opposite direction, until the reference voltage Vout keeps stable.

In addition, the output end of the operational amplifier A1 is also connected to the ground through the seventh resistor R7 and the first capacitor C1 which are connected in series. The first capacitor C1 plays a role of filtering, specifically, when the frequency of the voltage change output by the output end of the operational amplifier a1 is low, the impedance of the first capacitor C1 is high, so that the low-frequency voltage signal output by the output end of the operational amplifier a1 is transmitted to the control end of the second switching tube M2; when the voltage change frequency output by the output end of the operational amplifier a1 is higher and exceeds the operating bandwidth of the operational amplifier a1, at this time, the operational amplifier a1 cannot respond in time, and the impedance of the first capacitor C1 is smaller, so that the high-frequency voltage signal output by the output end of the operational amplifier a1 is short-circuited to the ground to prevent oscillation of the operational amplifier a 1; the seventh resistor R7 is used to prevent the output terminal of the operational amplifier a1 from being directly grounded, and to protect the output terminal of the operational amplifier a 1.

It should be noted that the reference voltage value Vout output by the bandgap reference circuit provided in the embodiment of the present application may be 1.2V, and at this time, the voltage VDD input by the voltage input terminal substantially exceeds 1.4V, which may satisfy the normal operation of the bandgap reference circuit.

However, as is known from the background art, when a solar cell is used as a power supply to supply power, the voltage fluctuation is large, and the voltage may drop to a relatively low value, so that a low-voltage and low-power consumption bandgap reference circuit is also required to have a high power supply rejection ratio, so as to reduce the influence on the output reference voltage of the bandgap reference circuit when the power supply voltage of the bandgap reference circuit changes.

The inventor researches and finds that it is generally difficult to design a pre-modulation voltage circuit with a high comparison ratio to increase the power supply rejection ratio of a bandgap reference circuit at a low voltage, because in order to increase the power supply rejection ratio of the bandgap reference circuit, a circuit designer generally adds a primary pre-modulation voltage circuit between a power supply and the bandgap reference circuit and then uses the voltage circuit to supply power to the bandgap reference circuit, and at this time, the power supply rejection ratio of a system consisting of the bandgap reference circuit and the primary pre-modulation voltage circuit is the sum of the power supply rejection ratio of the bandgap reference circuit and the power supply rejection ratio of the primary pre-modulation voltage circuit.

In the bandgap reference circuit provided in the embodiment of the present application, the power supply rejection ratio includes two parts, one is that the power supply rejection ratio of the operational amplifier circuit is converted to the power supply rejection ratio of the output terminal of the bandgap reference circuit, and the other is that the power supply rejection ratio of the other part is converted to the power supply rejection ratio of the output terminal of the bandgap reference circuit through the operational amplifier circuit.

Therefore, in the embodiment of the application, the improvement of the power supply rejection ratio of the bandgap reference circuit can be started from at least one of the following two aspects: firstly, the power supply rejection ratio of the operational amplification circuit is improved; and secondly, the gain of the operational amplifier circuit is improved.

First, in view of increasing the power supply rejection ratio of the operational amplifier circuit itself, the power supply of the operational amplifier a1 should be kept stable to increase the power supply rejection ratio of the operational amplifier a1 itself, and further, the power supply rejection ratio of the bandgap reference circuit should be increased by converting the power supply rejection ratio to the output terminal of the bandgap reference circuit.

Therefore, on the basis of the above embodiments, in an embodiment of the present application, as shown in fig. 7, the operational amplifier a1 further has a power supply input end, and the power supply input end of the operational amplifier a1 is connected to the second end of the second switch tube M2, so as to supply power to the operational amplifier a1 by using the reference voltage Vout output by the bandgap reference circuit, on one hand, the bias voltage generating circuit of the operational amplifier a1 can be omitted, thereby simplifying the circuit structure of the bandgap reference circuit; on the other hand, the reference voltage Vout output by the bandgap reference circuit is kept stable by the regulating action of the operational amplifier a1, so that the bias voltage of the operational amplifier a1 is stable, and the power supply rejection ratio of the operational amplifier a1 itself can be increased, and further, the power supply rejection ratio of the bandgap reference circuit can be increased by converting the bias voltage to the output end of the bandgap reference circuit. However, the application of the bandgap reference circuit provided in the present application is not limited to the supply of the reference voltage Vout output by the bandgap reference circuit to the operational amplifier a1, and in other embodiments of the present application, the supply of the bias voltage Vout to the operational amplifier a1 may be included, as the case may be.

Further, in view of increasing the gain of the operational amplifier circuit, in an embodiment of the present application, as shown in fig. 8, when the first input terminal of the operational amplifier a1 is the negative input terminal of the operational amplifier a1, and the second input terminal of the operational amplifier a1 is the positive input terminal of the operational amplifier a1, the operational amplifier circuit 200 further includes: a third switching tube M3 located between the second end of the second switching tube M2 and the end far away from the first resistor R1, wherein the first end of the third switching tube M3 is connected to the second end of the second switching tube M2, the second end is connected to the end far away from the first resistor R1, and the control end is connected to the output end of the operational amplifier a1, so that the gain of the operational amplifier circuit 200 is increased by adding the third switching tube M3 to the operational amplifier circuit 200.

The operation of the operational amplifier circuit 200 with the third switching tube M3 added is described in detail below.

It should be noted that, in the embodiment of the present application, as shown in fig. 8, the second end of the third switching tube M3 is connected to the end of the first resistor R1 that is far away, and the end of the first resistor R1 that is far away is connected to the control end of the second switching tube M2, so that the second end of the third switching tube M3 is connected to the control end of the second switching tube M2, and the second end of the third switching tube M3 is the output end of the operational amplifier circuit 200.

It should be noted that the output end of the operational amplifier a1 is connected to the control end of the third switching tube M3, and the second end of the third switching tube M3 is connected to the control end of the second switching tube M2, so that the voltage signal output by the operational amplifier a1 based on the magnitude of the voltage V1 input by the first input end and the voltage V2 input by the second input end is transmitted to the control end of the third switching tube M3, and after being amplified once by the third switching tube M3 as a first-stage single-tube operational amplifier, the amplified voltage is transmitted to the control end of the second switching tube M2 by the second end of the third switching tube M3, so as to adjust the second end voltage of the second switching tube M2, that is the reference voltage Vout output by the bandgap reference circuit.

Therefore, according to the bandgap reference circuit provided by the embodiment of the present application, by adding a single-transistor operational amplifier, that is, the third switching transistor M3, to increase the gain of the operational amplifier circuit, the power supply rejection ratio of the other parts except the operational amplifier circuit is increased, and the power supply rejection ratio of the bandgap reference circuit is increased by the operational amplifier circuit being converted to the power supply rejection ratio of the output terminal of the bandgap reference circuit.

Optionally, in an embodiment of the application, the third switching tube M3 is a PMOS tube, at this time, the first end of the third switching tube M3 is a source, the second end is a drain, and the control end is a gate, and as shown in fig. 8, the second end of the third switching tube M3 is the output end of the operational amplifier circuit 200. However, the third switch tube M3 is not limited in the present application, as the case may be.

In the embodiment of the present application, since the second terminal voltage of the third switching tube M3 changes in the opposite direction to its control terminal voltage (i.e., the voltage output by the output terminal of the operational amplifier circuit), that is, when the control terminal voltage of the third switching tube M3 increases, the voltage between its control terminal and its first terminal decreases, the current flowing through the third switching tube M3 decreases, and the voltage drop across the first resistor R1 connected in series with the third switching tube M3 decreases, so that the second terminal voltage of the third switching tube M3 decreases; when the voltage at the control end of the third switching tube M3 decreases, the voltage between the control end and the first end thereof increases, the current flowing through the third switching tube M3 increases, the voltage drop across the first resistor R1 connected in series with the third switching tube M3 increases, so that the voltage at the second end of the third switching tube M3 increases, therefore, the first input end of the operational amplifier a1 is the negative input end of the operational amplifier a1, the second input end of the operational amplifier a1 is the positive input end of the operational amplifier a1, that is, the negative input end of the operational amplifier a1 is connected to the first end of the second triode Q2, and the positive input end of the operational amplifier a1 is connected to the first end of the third triode Q3.

It should be noted that, in the embodiment of the present application, when the voltage VDD input by the voltage input terminal fluctuates, so that the reference voltage Vout changes, the adjustment process of the operational amplifier circuit 200 composed of the operational amplifier a1 and the third switching tube M3 is different from the adjustment process of the operational amplifier circuit 200 composed of only the operational amplifier a1 in the previous embodiment.

Specifically, when the voltage VDD input by the voltage input terminal is increased to increase the reference voltage Vout, the voltage V1 input by the negative input terminal of the operational amplifier a1 is greater than the voltage V2 input by the positive input terminal thereof, so that the voltage output by the output terminal of the operational amplifier a1 is decreased, and further the voltage at the second terminal of the third switching tube M3 is increased, that is, the voltage at the output terminal of the operational amplifier circuit 200 is increased, the voltage at the control terminal of the second switching tube M2 is pulled high, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof is decreased, so that the current flowing through the second switching tube M2 is decreased, and further the voltage at the second terminal of the second switching tube M2 is decreased, and the reference voltage Vout is pulled low until the reference voltage Vout is kept stable.

When the voltage VDD input by the voltage input terminal is decreased to decrease the reference voltage Vout, the voltage V1 input by the negative input terminal of the operational amplifier a1 is smaller than the voltage V2 input by the positive input terminal thereof, the voltage output by the output terminal of the operational amplifier a1 is increased, and further the voltage of the second terminal of the third switching tube M3 is decreased, that is, the voltage of the output terminal of the operational amplifier circuit 200 is decreased, the voltage of the control terminal of the second switching tube M2 is pulled down, the voltage between the control terminal of the second switching tube M2 and the first terminal thereof is increased, so that the current flowing through the second switching tube M2 is increased, and further the voltage of the second terminal of the second switching tube M2 is increased to pull up the reference voltage Vout until the reference voltage Vout is kept stable.

On the basis of the above embodiments, in an embodiment of the present application, in order to continuously increase the gain of the bandgap reference circuit, as shown in fig. 9, the operational amplifier circuit 200 further includes:

a fourth switching tube M4 located between the second end of the first switching tube M1 and the end of the first resistor R1 far away from the ground, where the first end of the fourth switching tube M4 is connected to the second end of the first switching tube M1, the second end is connected to the end of the first resistor R1 far away from the ground, the control end is connected to the bias voltage input end, and a bias voltage Vbias is input, where the bias voltage Vbias is greater than the conduction voltage drop of the fourth switching tube M4, so that the fourth switching tube M4 is in a conducting state.

It should be noted that, in the embodiment of the present application, since the first end of the fourth switching tube M4 is connected to the second end of the first switching tube M1, the second end of the first switching tube M1 is connected to the control end thereof, and the control end thereof is connected to the control end of the second switching tube M2, the first end of the fourth switching tube M4 is connected to the control end of the second switching tube M2; since the second end of the fourth switching tube M4 is connected to the end of the first resistor R1 that is far away from the ground, and the end of the first resistor R1 that is far away from the ground is connected to the second end of the third switching tube M3, the second end of the fourth switching tube M4 is connected to the second end of the third switching tube M3, and at this time, the output end of the operational amplifier circuit is the first end of the fourth switching tube M4.

Optionally, in an embodiment of the present application, the fourth switching transistor M4 is an NMOS transistor, and at this time, the first terminal of the fourth switching transistor M4 is a drain, the second terminal thereof is a source, and the control terminal thereof is a gate. However, the present application does not limit this, and the specific case may be.

It should be noted that, in the embodiment of the present application, as shown in fig. 9 again, the output end of the operational amplifier a1 is connected to the control end of the third switch tube M3, the second end of the third switch tube M3 is connected to the second end of the fourth switch tube M4, and the first end of the fourth switch tube M4 is connected to the control end of the second switch tube M2, so that the voltage signal output by the operational amplifier a2 based on the magnitude of the voltage V1 input by the first input end and the voltage V2 input by the second input end thereof is transmitted to the control end of the third switch tube M3, amplified once by the third switch tube M3 as a first-stage single-tube operational amplifier, transmitted to the second end of the fourth switch tube M4 by the second end of the third switch tube M3, and amplified for the second time by the fourth switch tube M4 as a second-stage single-tube operational amplifier, and the voltage is transmitted to the control end of the second switching tube M2 from the first end of the fourth switching tube M4, so as to adjust the voltage of the second end of the second switching tube M2, that is, the reference voltage Vout output by the bandgap reference circuit.

It should be noted that, in the embodiment of the present application, since the fourth switching tube M4 is added between the second end of the first switching tube M1 and the end far away from the first resistor R1, when VDD input by the voltage input end is greater than the sum of the conduction voltage drops of the first switching tube M1 and the fourth switching tube M4, a path formed by the first switching tube M1, the fourth switching tube M4 and the first resistor R1 starts to conduct.

It should be noted that, in this embodiment of the application, since the second end of the third switching tube M3 is connected to the second end of the fourth switching tube M4, and the second end of the fourth switching tube M4 is connected to the control end of the second switching tube M2, when the third switching tube M3 controls the voltage of the second end to change based on the voltage signal output by the operational amplifier a1 received by the control end, the voltage of the second end of the fourth switching tube M4 changes in the same direction, so that the voltage of the first end of the fourth switching tube M4 changes in the same direction, and thus the control end voltage of the second switching tube M2 changes in the same direction, that is, when the voltage VDD input by the voltage input end fluctuates and the reference voltage Vout changes, the adjustment process of the operational amplifier circuit 200 composed of the operational amplifier a1, the third switching tube M3 and the fourth switching tube M4 and the adjustment process of the operational amplifier a1 and the third switch 1 and the operational amplifier a1 and the fourth switch M4 The adjustment process of the operational amplifier circuit 200 composed of the tube M3 is the same, and since the adjustment process has been described in detail in the foregoing embodiment, the detailed description is not repeated here.

As can be seen from this, in the embodiment of the present application, the bandgap reference circuit further increases the gain of the operational amplifier circuit by adding two stages of single-tube operational amplifiers, that is, the third switch tube M3 and the fourth switch tube M4, so as to further increase the power supply rejection ratio of the other parts except the operational amplifier circuit, which is converted by the operational amplifier circuit into the power supply rejection ratio of the output terminal of the bandgap reference circuit, and further increase the power supply rejection ratio of the bandgap reference circuit.

In the above embodiments, the gain of the operational amplifier circuit is increased by adding two stages of single-tube operational amplifiers, and the power supply rejection ratio of the bandgap reference circuit is further improved. Therefore, on the basis of the above-mentioned embodiments, in an embodiment of the present application, as shown in fig. 10, the operational amplifier circuit 200 further includes:

a second capacitor C2, wherein a first terminal of the second capacitor C2 is connected to the first terminal of the fourth switching tube M4, and a second terminal thereof is connected to the second terminal of the fourth switching tube M4.

It should be noted that, in the embodiment of the present application, the output end of the operational amplifier circuit 100 is the first end of the fourth switching tube M4, and outputs the voltage signal Vop, at this time, a small-signal equivalent model of the fourth switching tube M4 is as shown in fig. 11, where Iin is the current output by the second end of the third switching tube M3.

Through derivation of a small-signal model, the gain of the fourth switching tube M4 can be obtained as follows:

gm1 is the transconductance of the fourth switching transistor M4, which is determined by the size of the fourth switching transistor M4, and C2 is the capacitance of the second capacitor.

Therefore, the gain of the two-stage single-tube operational amplifier composed of the third switching tube M3 and the fourth switching tube M4 is:

gm2 is the transconductance of the third switching tube M3, and is determined by the size of the third switching tube M3.

As can be seen from equation (8), in the embodiment of the present application, the operational amplifier circuit generates a zero point and a pole by adding the third capacitor C3, where the generated zero point corresponds to the S value when the numerator in equation (8) is equal to 0, and is set as S1, which is specifically:

the generated pole corresponds to the value of S when the denominator in equation (8) is equal to 0, which is set as S2, and is specifically:

it can be seen from the combination of the formula (9) and the formula (10) that by adjusting the size of the fourth switching tube M4 and the resistances of the first resistor R1 and the sixth resistor R6, a pole (corresponding to S2) can be placed outside the operating bandwidth of the operational amplifier circuit, a zero (corresponding to S1) can be placed within the operating bandwidth of the operational amplifier circuit, and the zero (corresponding to S1) is located in front of the pole (S2), so that the phase margin of the operational amplifier circuit is increased, and the stability of the operational amplifier circuit is further improved.

It should be further noted that, in the bandgap reference circuit provided in this embodiment of the application, the first switching tube M1 and the second switching tube M2 are input by a common source, when the voltage VDD input by the voltage input terminal has small signal fluctuation, because the output impedance from the first end of the fourth switching tube M4 to ground is much larger than that of the sixth resistor R6, the fluctuation of the voltage VDD input by the voltage input terminal is almost completely transmitted to the control end of the second switching tube M2 through the first end of the first switching tube M1 and the control end thereof, and the first end of the second switching tube Q2 is also connected to the voltage input terminal, so that the voltage change between the control end of the second switching tube M2 and the first end thereof is small, and the voltage between the control end of the second switching tube M2 and the first end thereof is kept stable in combination with the adjustment function of the operational amplifier circuit 200, therefore, the voltage at the second end of the second switching tube M2 is kept stable, and the reference voltage Vout output by the bandgap reference circuit is kept stable.

In addition, in view of the fact that the operational amplifier circuit can respond in time when the variation frequency of the voltage VDD inputted from the voltage input terminal is high, on the basis of the above embodiment, in an embodiment of the present application, as shown in fig. 12, the bandgap reference circuit further includes:

a third capacitor C3, wherein a first end of the third capacitor C3 is connected to the second end of the second switch tube M2, and a second end is connected to the second input end of the operational amplifier circuit 200.

Optionally, on the basis of the foregoing embodiment, in an embodiment of the present application, as shown in fig. 12, the operational amplifier circuit 200 includes the operational amplifier a1, the third switching tube M3, the fourth switching tube M4, the seventh resistor R7, and the first capacitor C1, a first input end of the operational amplifier circuit is a negative input end of the operational amplifier a1, a second input end of the operational amplifier circuit is a positive input end of the operational amplifier a1, and therefore a second end of the third capacitor C3 is connected to a positive input end of the operational amplifier a 1.

It should be noted that, in the embodiment of the present application, when the frequency of the voltage VDD input by the voltage input terminal is high, the current change flowing through the second transistor Q2 is different from the current change flowing through the third transistor Q3, so that the transmission process of the voltage V1 input by the negative input terminal of the operational amplifier a1 and the voltage V2 input by the positive input terminal thereof cannot respond in time, at this time, the bandgap reference circuit introduces the fourth capacitor C4, the high-frequency voltage signal of the voltage VDD input by the voltage input terminal is timely transmitted to the positive input terminal of the operational amplifier a1 through the fourth capacitor C4, then the operational amplifier a1 controls the voltage change output by the output terminal thereof based on the magnitudes of the voltage V2 input by the positive input terminal thereof and the voltage V1 input by the negative input terminal thereof, and the voltage change passes through the control terminal of the third switching tube M3 and the second terminal thereof, the second end and the first end of the fourth switching tube M4, and the control end of the second switching tube M2 are transmitted to the second end of the second switching tube M2, and finally, when the voltage V2 input at the positive input end of the operational amplifier a1 and the voltage V1 input at the negative input end thereof are equal again, the bandgap reference circuit outputs a stable reference voltage Vout.

It should be noted that, in the embodiment of the present application, in the overall operational amplifier circuit composed of the operational amplifier a1, the seventh resistor R7 and the first capacitor C1 connected in series with the output end thereof, the cutoff frequency of the overall operational amplifier circuit is equal to the product of the gain of the operational amplifier a1 and the capacitance of the first capacitor C1, and since the gain of the operational amplifier a1 is high, the cutoff frequency of the overall operational amplifier circuit is very high and higher than the change frequency of the high-frequency voltage signal inputted from the voltage input end through which the third capacitor C3 passes, that is, the high-frequency voltage signal inputted from the voltage input end through which the third capacitor C3 passes is still within the operating bandwidth of the overall operational amplifier circuit, so that the operational amplifier a1 can respond in time and further transmit the response signal to the control end of the third switching tube M3, without being short-circuited to ground by said first capacitor C1.

In addition, an embodiment of the present application further provides an electronic device, including the bandgap reference circuit provided in any of the embodiments, where a specific working process of the bandgap reference circuit has been described in detail in each of the embodiments, and is not described herein again.

In summary, the bandgap reference circuit and the electronic device provided in the embodiments of the present application include a first switching tube, a second switching tube, a first resistor, a control circuit, and an operational amplifier circuit, where the first switching tube and the second switching tube form a current mirror structure, and generate a first control voltage based on a voltage input by a voltage input terminal; the control circuit generates a first adjusting voltage and a second adjusting voltage based on the first control voltage, and the operational amplification circuit adjusts the control end voltage of the second switching tube based on the first adjusting voltage and the second adjusting voltage until the band-gap reference circuit establishes a normal working point and outputs a reference voltage. Therefore, the bandgap reference circuit provided by the embodiment of the application can break a zero degeneracy point and realize self-starting without additionally adding a starting circuit.

All parts in the specification are described in a mode of combining parallel and progressive, each part is mainly described to be different from other parts, and the same and similar parts among all parts can be referred to each other.

In the above description of the disclosed embodiments, features described in various embodiments in this specification can be substituted for or combined with each other to enable those skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bandgap reference circuit, comprising: a first switch tube, a second switch tube, a first resistor, a control circuit and an operational amplifier circuit, wherein,

the first switching tube and the second switching tube form a current mirror structure, and a first control voltage is generated based on the voltage input by the voltage input end; the control circuit generates a first regulation voltage and a second regulation voltage based on the first control voltage, and the operational amplification circuit regulates the control end voltage of the second switching tube based on the first regulation voltage and the second regulation voltage until the band-gap reference circuit outputs a reference voltage;

the control circuit includes: the first branch, the second branch and the third branch are electrically connected between the second end of the second switching tube and the ground end; the first branch includes:

the second branch includes:

the third branch includes:

the first end of the second triode is connected with the first input end of the operational amplification circuit and outputs the first regulating voltage; and the first end of the third triode is connected with the second input end of the operational amplification circuit and outputs the second regulating voltage.

2. The bandgap reference circuit of claim 1, wherein the control circuit generates a first regulated voltage for output through a third terminal thereof and a second regulated voltage for output through a fourth terminal thereof based on the first control voltage inputted through the first terminal thereof; the operational amplification circuit adjusts the voltage of the control end of the second switching tube based on the first adjusting voltage input by the first input end and the second adjusting voltage input by the second input end until the band-gap reference circuit outputs the reference voltage.

3. The bandgap reference circuit according to claim 1, wherein the first end of the first branch is connected to the second end of the second switching transistor, and the second end is grounded, so as to generate a second control voltage based on the first control voltage inputted from the first end, and output the second control voltage to the control end of the second branch through the output end;

4. The bandgap reference circuit of claim 3, wherein the second resistor, the third resistor and the fifth resistor have equal resistance values.

5. The bandgap reference circuit of claim 1, further comprising:

6. The bandgap reference circuit according to claim 4, wherein the operational amplifier circuit comprises: an operational amplifier, a seventh resistor and a first capacitor, wherein,

7. The bandgap reference circuit as claimed in claim 6, wherein the operational amplifier further has a power input terminal, and the power input terminal of the operational amplifier is connected to the second terminal of the second switch tube.

8. The bandgap reference circuit as recited in claim 6 or 7, wherein the first input of the operational amplifier is a positive input of the operational amplifier, and the second input of the operational amplifier is a negative input of the operational amplifier.

9. The bandgap reference circuit according to claim 6 or 7, wherein the first input terminal of the operational amplifier is a negative input terminal of the operational amplifier, the second input terminal of the operational amplifier is a positive input terminal of the operational amplifier, and the operational amplifier circuit further comprises:

10. The bandgap reference circuit according to claim 9, wherein the operational amplifier circuit further comprises:

11. The bandgap reference circuit according to claim 10, further comprising:

12. The bandgap reference circuit of claim 1, further comprising:

and a first end of the third capacitor is connected with the second end of the second switch tube, and a second end of the third capacitor is connected with the second input end of the operational amplification circuit.

13. An electronic device comprising the bandgap reference circuit as claimed in any of claims 1 to 12.