A power supply circuit for improving output voltage accuracy

Abstract

The present application provides a power supply circuit for improving the accuracy of output voltage. The power supply circuit includes a voltage generator and a voltage regulator. The voltage generator is connected to an external power supply voltage VIN, and outputs a first power supply voltage VA and a second power supply voltage VB; in the voltage regulator, the external power supply voltage VIN is grounded through a first controllable current source G1, a first resistor R1, and a second resistor R2 in sequence; the first power supply voltage VA is grounded through a current source module, a first switch tube M1, and a third resistor R3 in sequence; the first power supply voltage VA is also grounded through a current source module, a second switch tube M2, and a fourth resistor R4 in sequence; the control end of the first switch tube M1 is connected to the second power supply voltage VB, the control end of the second switch tube M2 is connected between the first resistor R1 and the second resistor R2, the output end of the power supply circuit is connected between the first controllable current source G1 and the first resistor R1, and the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal. The power supply circuit of the present application can improve the accuracy of the output voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply circuits, and in particular to a power supply circuit capable of improving output voltage accuracy. Background Art

[0002] In the prior art, the power supply circuit inside the chip usually includes a voltage regulator and multiple voltage generators, and the multiple voltage generators supply power to the voltage regulator. However, this design has the following problems: on the one hand, the structure of the existing voltage regulator usually cannot fully achieve the precise matching of the current and voltage of each path, which reduces the output voltage accuracy of the power supply circuit. On the other hand, multiple voltage generators need to be set inside the chip, which increases the volume of the chip, and because the accuracy of the power supply voltage output by different voltage generators is different, the accuracy of the output voltage of the power supply circuit is further reduced. Summary of the invention

[0003] An embodiment of the present invention provides a power supply circuit for improving output voltage accuracy, and the power supply circuit can ensure output of a high-precision output voltage.

[0004] According to one aspect of the present invention, there is provided a power supply circuit for improving output voltage accuracy, comprising a voltage generator and a voltage regulator, wherein the voltage generator is connected to an external power supply voltage VIN and outputs a first power supply voltage VA and a second power supply voltage VB;

[0005] In the voltage regulator, the external power supply voltage VIN is grounded through the first controllable current source G1, the first resistor R1 and the second resistor R2 in sequence; the first power supply voltage VA is grounded through the current source module, the first switch tube M1 and the third resistor R3 in sequence; the first power supply voltage VA is also grounded through the current source module, the second switch tube M2 and the fourth resistor R4 in sequence, and the voltage regulator includes a control module, the external power supply voltage VIN is connected to the control module, and the control module is connected to the current output end of the first switch tube M1, the current source module, the first controllable current source G1 and the ground end;

[0006] The control end of the first switch tube M1 is connected to the second power supply voltage VB, the control end of the second switch tube M2 is connected between the first resistor R1 and the second resistor R2, the output end of the power supply circuit is connected between the first controllable current source G1 and the first resistor R1, the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal, and the control module is used to control the current flowing through the first switch tube M1 to be equal to the current flowing through the second switch tube M2, so that the control end voltage of the second switch tube M2 is equal to the control end voltage of the first switch tube M1.

[0007] In a possible implementation, when the voltage regulator is in a stable working state, the control terminal voltage of the second switch tube M2 is equal to the second power supply voltage VB, so that the output terminal voltage VOUT of the power supply circuit satisfies the following formula:

[0008] .

[0009] In a possible implementation, in the control module, the external power supply voltage VIN is further connected to ground via a fifth resistor R5, a fourth switch tube M4 and a sixth resistor R6 in sequence;

[0010] The negative control terminal of the first controllable current source G1 is connected to one end of the fifth resistor R5 close to the fourth switch tube M4 , and the positive control terminal and the input terminal of the first controllable current source G1 are both connected to the external power supply voltage VIN.

[0011] In a possible implementation, the current source module includes:

[0012] A second controllable current source G2, whose positive control terminal and input terminal are both connected to the first power supply voltage VA, and whose output terminal is connected to the current input terminals of the first switch tube M1 and the second switch tube M2;

[0013] a third controllable current source G3, whose positive control terminal and input terminal are both connected to the first power supply voltage VA, whose negative control terminal is connected to the negative control terminal of the second controllable current source G2, and whose output terminal is connected to the control terminal of the fourth switch tube M4;

[0014] The control module includes a fourth controllable current source G4, a positive control end of the fourth controllable current source G4 is connected to the current output end of the first switch tube M1, an input end is connected to the output end of the third controllable current source G3 and the control end of the fourth switch tube M4, and a negative control end and an output end are both grounded.

[0015] In a possible implementation, in the current source module, the first supply voltage VA is further connected to ground via a seventh resistor R7 and a first current source I1 in sequence;

[0016] One end of the seventh resistor R7 close to the first current source I1 is connected to the negative control end of the second controllable current source G2.

[0017] In a possible implementation, the voltage regulator further includes a third switch tube M3, a current input end of the third switch tube M3 is connected to the negative control end of the first controllable current source G1, a current output end of the third switch tube M3 is connected to the current input end of the fourth switch tube M4, and a control end of the third switch tube M3 is connected to the first supply voltage VA.

[0018] In a possible implementation, the first power supply voltage VA is greater than the second power supply voltage VB, and a difference between the first power supply voltage VA and the second power supply voltage VB is greater than or equal to a turn-on threshold voltage of the switch tube.

[0019] In a possible implementation, the ratio of the controllable current generated by the second controllable current source G2 to the controllable current generated by the third controllable current source G3 is 2:1;

[0020] The second controllable current source G2, the first switch tube M1 and the third resistor R3 form a first branch, and the ratio of the current of the first branch to the controllable current generated by the fourth controllable current source G4 is 1:1.

[0021] In a possible implementation, the voltage generator includes a power supply branch, in which the external power supply voltage VIN is grounded in sequence through a fifth switch tube M5, a first transistor Q1, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a second transistor Q2, and the first transistor Q1 and the second transistor Q2 are both connected by diodes;

[0022] The first power supply end of the voltage generator is connected to the current output end of the fifth switch tube M5, and outputs the first power supply voltage VA, and the second power supply end of the voltage generator is connected between the eighth resistor R8 and the ninth resistor R9, and outputs the second power supply voltage VB;

[0023] The first supply voltage VA satisfies the following formula:

[0024] ;

[0025] The second supply voltage VB satisfies the following formula:

[0026] ;

[0027] Wherein, ID represents the power supply current generated in the power supply branch, VBE1 represents the voltage difference between the base and the emitter of the first transistor Q1, and VBE2 represents the voltage difference between the base and the emitter of the second transistor Q2.

[0028] In a possible implementation, in the voltage generator, the external power supply voltage VIN is grounded through the first diode D1, the eleventh resistor R11, the third transistor Q3 and the fifth controllable current source G5 in sequence, and the base of the third transistor Q3 is connected between the eighth resistor R8 and the ninth resistor R9;

[0029] The voltage generator also includes a twelfth resistor R12 and a fourth transistor Q4, one end of the twelfth resistor R12 is connected to the cathode of the first diode D1, the other end of the twelfth resistor R12 is connected to the collector of the fourth transistor Q4, the emitter of the fourth transistor Q4 is connected to the input end of the fifth controllable current source G5, and the base of the fourth transistor Q4 is connected between the ninth resistor R9 and the tenth resistor R10.

[0030] In a possible implementation, the ratio of the number of the third transistor Q3 to the number of the fourth transistor Q4 is 1:K;

[0031] The parameters of the first transistor Q1 and the second transistor Q2 are the same.

[0032] In a possible implementation, the first supply voltage VA satisfies the following formula:

[0033] ;

[0034] The second supply voltage VB satisfies the following formula:

[0035] ;

[0036] Wherein, VBE represents the voltage difference between the base and the emitter of the first transistor Q1 and the second transistor Q2, and Vt represents the thermal voltage of the transistor.

[0037] In a possible implementation, in the voltage generator, the external power supply voltage VIN is further connected to ground via a sixth controllable current source G6, a sixth switch tube M6 and a second diode D2 in sequence;

[0038] The voltage generator further includes a seventh switch tube M7, a current input end of the seventh switch tube M7 is connected to the external power supply voltage VIN, a current output end of the seventh switch tube M7 is connected between the eighth resistor R8 and the ninth resistor R9, and a control end of the seventh switch tube M7 is connected to the control end of the sixth switch tube M6 and is incorporated into the current input end of the sixth switch tube M6;

[0039] When the voltage at the current output terminal of the seventh switch tube M7 is less than the forward conduction voltage drop VD2 of the second diode D2, the seventh switch tube M7 is turned on, thereby clamping the voltage at the current output terminal of the seventh switch tube M7 at VD2; when the voltage at the current output terminal of the seventh switch tube M7 is greater than VD2, the voltage difference between the base and the emitter of the third transistor Q3 and the fourth transistor Q4 is greater than the forward conduction voltage drop of the transistor, thereby ensuring that the third transistor Q3 and the fourth transistor Q4 are smoothly turned on.

[0040] In a possible implementation, there are multiple second diodes D2, and the multiple second diodes D2 are connected in series.

[0041] In a possible implementation, in the voltage generator, the external power supply voltage VIN is also grounded through the seventh controllable current source G7, the eighth switch tube M8 and the thirteenth resistor R13 in sequence, and the control end of the eighth switch tube M8 is connected to the collector of the third triode Q3; the external power supply voltage VIN is also grounded through the seventh controllable current source G7, the ninth switch tube M9 and the fourteenth resistor R14 in sequence, and the control end of the ninth switch tube M9 is connected to the collector of the fourth triode Q4.

[0042] In a possible implementation, in the voltage generator, the external power supply voltage VIN is further grounded through an eighth controllable current source G8, a tenth switch tube M10, and a thirteenth resistor R13 in sequence; the external power supply voltage VIN is further grounded through a ninth controllable current source G9, an eleventh switch tube M11, and a fourteenth resistor R14 in sequence;

[0043] The control ends of the tenth switch tube M10 and the eleventh switch tube M11 are connected and merged into the current input end of the tenth switch tube M10 , and the current input end of the eleventh switch tube M11 is connected to the control end of the fifth switch tube M5 .

[0044] In a possible implementation, the resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12 are equal;

[0045] The resistance values ​​of the thirteenth resistor R13 and the fourteenth resistor R14 are equal.

[0046] In a possible implementation, in the voltage generator, the external power supply voltage VIN is also grounded through a fifteenth resistor R15 and a tenth controllable current source G10 in sequence; the external power supply voltage VIN is also grounded through a second current source I2 and a sixteenth resistor R16 in sequence;

[0047] The positive control terminal of the tenth controllable current source G10 is connected to the positive control terminal of the fifth controllable current source G5 and the end of the sixteenth resistor R16 close to the second current source I2, the negative control terminal and the output terminal of the tenth controllable current source G10 are both grounded, the end of the fifteenth resistor R15 close to the tenth controllable current source G10 is connected to the negative control terminals of the seventh controllable current source G7, the eighth controllable current source G8, the ninth controllable current source G9 and the sixth controllable current source G6, the negative control terminal of the fifth controllable current source G5 is grounded, and the positive control terminals and input terminals of the sixth controllable current source G6, the seventh controllable current source G7, the eighth controllable current source G8 and the ninth controllable current source G9 are all connected to the external power supply voltage VIN.

[0048] According to the solution of the present application, when the power supply circuit is in a stable working state, the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2. Therefore, at this time, a fourth resistor R4 is set in the branch of the second switch tube M2, and the resistance value of the fourth resistor R4 is designed to be equal to the third resistor R3. Therefore, when the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2, the voltage drop in the third resistor R3 and the fourth resistor R4 is the same, so that when the circuit is in a stable working state, the first switch tube M1 is equal to the branch current flowing through the second switch tube M2. The voltages at the current output ends of the first switch tube M1 and the second switch tube M2 are completely equal, so it can be obtained that when the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2, and the voltages at the current output ends of the first switch tube M1 and the second switch tube M2 are also completely equal, the voltages at the control ends of the first switch tube M1 and the second switch tube M2 must be completely equal, thereby ensuring that when the circuit is in a stable working state, the current voltages of each path in the circuit are completely matched, and the voltage at the control end of the second switch tube M2 is precisely equal to the second power supply voltage VB. Therefore, through the above circuit structure, the accuracy of the output voltage VOUT can be improved.

[0049] In the power supply circuit of the present application, only one voltage generator is provided to generate two high-precision supply voltages that are not affected by temperature and have the same precision, thereby ensuring that after the two high-precision supply voltages with the same precision are input into the voltage regulator, the circuit of the present application can output a high-precision output voltage. At the same time, since only one voltage generator is provided to generate two supply voltages, the volume of the circuit is reduced.

[0050] In the voltage generator of the present application, a first supply voltage with current capability and a second supply voltage without current capability are provided, and after reasonable combination with the voltage regulator, the power supply circuit of the present application with improved output voltage accuracy is obtained.

[0051] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 A schematic circuit structure diagram of a power supply circuit for improving output voltage accuracy according to an embodiment of the present invention is shown;

[0054] Figure 2 A schematic circuit structure diagram of a power supply circuit for improving output voltage accuracy according to another embodiment of the present invention is shown;

[0055] Figure 3 A schematic circuit structure diagram of a voltage generator according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0056] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0057] Figure 1 FIG. 1 is a schematic circuit diagram of a power supply circuit for improving output voltage accuracy according to an embodiment of the present invention. Figure 1As shown, the power supply circuit includes a voltage generator and a voltage regulator. The voltage generator is connected to an external power supply voltage VIN and outputs a first power supply voltage VA and a second power supply voltage VB. In the voltage regulator, the external power supply voltage VIN is connected to the ground through the first controllable current source G1, the first resistor R1 and the second resistor R2 in sequence; the first power supply voltage VA is connected to the ground through the current source module 1, the first switch tube M1 and the third resistor R3 in sequence; the first power supply voltage VA is also connected to the ground through the current source module 1, the second switch tube M2 and the fourth resistor R4 in sequence; the voltage regulator includes a control module, the external power supply voltage VIN is connected to the control module, and the control module is connected to the current output end of the first switch tube M1, the current source module 1, the first controllable current source G1 and the ground end. Among them, the control end of the first switch tube M1 is connected to the second power supply voltage VB, the control end of the second switch tube M2 is connected between the first resistor R1 and the second resistor R2, the output end of the power supply circuit is connected between the first controllable current source G1 and the first resistor R1, the third resistor R3 and the fourth resistor R4 have equal resistance values, and the control module is used to control the current flowing through the first switch tube M1 to be equal to the current flowing through the second switch tube M2, so that the control end voltage of the second switch tube M2 is equal to the control end voltage of the first switch tube M1. Among them, the first power supply voltage VA is greater than the second power supply voltage VB, and the difference between the two is greater than or equal to the turn-on threshold voltage of the switch tube.

[0058] Depend on Figure 1 It can be seen that when the power supply circuit is in a stable working state, the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2. Therefore, at this time, the third resistor R3 is set in the branch of the first switch tube M1, and the fourth resistor R4 is set in the branch of the second switch tube M2, and the resistance value of the fourth resistor R4 is designed to be equal to the resistance value of the third resistor R3. Therefore, when the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2, the voltage drop in the third resistor R3 and the fourth resistor R4 is the same, so that when the circuit is in a stable working state, When the circuit is in a stable working state, the voltages at the current output ends of the first switch tube M1 and the second switch tube M2 are completely equal. Therefore, it can be obtained that when the branch current flowing through the first switch tube M1 is equal to the branch current flowing through the second switch tube M2, and the voltages at the current output ends of the first switch tube M1 and the second switch tube M2 are also completely equal, the voltages at the control ends of the first switch tube M1 and the second switch tube M2 must be completely equal, thereby ensuring that when the circuit is in a stable working state, the current voltages of each path in the circuit are completely matched, and the voltage at the control end of the second switch tube M2 is precisely equal to the second power supply voltage VB. Therefore, through the above circuit structure, the accuracy of the output voltage VOUT can be improved.

[0059] According to the above analysis, when the power supply circuit is in a stable working state, the voltage at the control terminal of the second switch tube M2 is exactly equal to the second power supply voltage VB, that is, , so at this time, the output voltage VOUT of the power supply circuit satisfies the following formula: .

[0060] Figure 2 FIG. 2 is a schematic circuit diagram of a power supply circuit for improving output voltage accuracy according to another embodiment of the present invention. Figure 2 As shown, in a possible implementation, the control module 2 includes a fifth resistor R5, a fourth switch tube M4 and a sixth resistor R6, and the external power supply voltage VIN is grounded through the fifth resistor R5, the fourth switch tube M4 and the sixth resistor R6 in sequence. The negative control terminal of the first controllable current source G1 is connected to an end of the fifth resistor R5 close to the fourth switch tube M4, and the positive control terminal and the input terminal of the first controllable current source G1 are both connected to the external power supply voltage VIN.

[0061] In a possible implementation, the voltage regulator also includes a third switch tube M3, a current input end of the third switch tube M3 is connected to the negative control end of the first controllable current source G1, a current output end of the third switch tube M3 is connected to the current input end of the fourth switch tube M4, and a control end of the third switch tube M3 is connected to the first power supply voltage VA.

[0062] In a possible implementation, the current source module includes a second controllable current source G2 and a third controllable current source G3. The control module includes a fourth controllable current source G4. The positive control terminal and the input terminal of the second controllable current source G2 are both connected to the first power supply voltage VA, and the output terminal is connected to the current input terminals of the first switch tube M1 and the second switch tube M2. The positive control terminal and the input terminal of the third controllable current source G3 are both connected to the first power supply voltage VA, the negative control terminal is connected to the negative control terminal of the second controllable current source G2, and the output terminal is connected to the control terminal of the fourth switch tube M4. The positive control terminal of the fourth controllable current source G4 is connected to the current output terminal of the first switch tube M1, the input terminal is connected to the output terminal of the third controllable current source G3 and the control terminal of the fourth switch tube M4, and the negative control terminal and the output terminal are both grounded.

[0063] In a possible implementation, in the current source module, the first supply voltage VA is also grounded via the seventh resistor R7 and the first current source I1 in sequence. One end of the seventh resistor R7 close to the first current source I1 is connected to the negative control end of the second controllable current source G2.

[0064] In the embodiment of the present application, the third switch tube M3 plays a role in isolating the high voltage. Figure 1 All devices below the third switch tube M3 can be low-voltage devices, thereby reducing the volume of the circuit.

[0065] The working principle of the power supply circuit for improving output voltage accuracy in the embodiment of the present application is as follows:

[0066] When the circuit is powered on, the external power supply voltage VIN is input into the voltage generator, and the voltage generator generates a high-precision first power supply voltage VA and a second power supply voltage VB; at the same time, the first current source I1 generates a first current, so at this time, a voltage drop is generated across the seventh resistor R7, and the second controllable current source G2 generates a second controllable current according to the voltage drop, and the third controllable current source G3 generates a third controllable current according to the voltage drop, and the ratio of the second controllable current to the third controllable current is 2:1.

[0067] At this time, the second power supply voltage VB is input to the control end of the first switch tube M1, and the voltage of the current input end of the first switch tube M1 is pulled up to the first power supply voltage VA through the second controllable current source G2, and because the difference between the first power supply voltage VA and the second power supply voltage VB is greater than or equal to the turn-on threshold voltage of the switch tube, at this time, the first switch tube M1 is turned on, and a first branch current is generated in the first branch composed of the second controllable current source G2, the first switch tube M1 and the third resistor R3. Therefore, a voltage drop is generated across the third resistor R3, and the fourth controllable current source G4 generates a fourth controllable current according to the voltage drop, and the ratio of the first branch current to the fourth controllable current is 1:1.

[0068] Since the output voltage VOUT is approximately 0 when the circuit is just powered on, the voltage at the control end of the second switch tube M2 is also approximately 0. Since the current input ends of the first switch tube M1 and the second switch tube M2 are connected, it can be obtained that the voltage difference between the current input end and the control end of the first switch tube M1 is smaller than the voltage difference between the current input end and the control end of the second switch tube M2. Therefore, a second branch current is generated in the second branch composed of the second controllable current source G2, the second switch tube M2 and the fourth resistor R4, and the first branch current flowing through the first switch tube M1 is smaller than the second branch current flowing through the second switch tube M2. Since the sum of the first branch current and the second branch current is equal to the second controllable current, the first branch current is equal to the fourth controllable current and is smaller than half of the second controllable current, and the third controllable current is equal to half of the second controllable current. Therefore, it can be obtained that the fourth controllable current is smaller than the third controllable current. Therefore, the voltage at the control end of the fourth switch tube M4 is pulled up to the first power supply voltage VA, and the fourth switch tube M4 is turned on. At this time, the voltage at the current output end of the third switch tube M3 is pulled down through the fourth switch tube M4 and the sixth resistor R6, and the control end of the third switch tube M3 inputs the first power supply voltage VA. Therefore, the third switch tube M3 is turned on, and the third branch current flows through the fifth resistor R5. Therefore, a voltage drop is generated across the fifth resistor R5, and the first controllable current source G1 generates a first controllable current according to the voltage drop. The first controllable current flows into the first resistor R1 and the second resistor R2, and the output voltage VOUT starts to increase.

[0069] As the output voltage VOUT gradually increases, the voltage at the control end of the second switch tube M2 also gradually increases. When the voltage at the control end of the second switch tube M2 increases to be greater than the second power supply voltage VB, the voltage difference between the current input end and the control end of the first switch tube M1 is greater than the voltage difference between the current input end and the control end of the second switch tube M2. Therefore, the first branch current flowing through the first switch tube M1 is greater than the second branch current flowing through the second switch tube M2. Since the sum of the first branch current and the second branch current is equal to the second controllable current, the first branch current is equal to the fourth controllable current. The fourth controllable current is greater than the third controllable current, and the third controllable current is equal to half of the second controllable current. Therefore, the fourth controllable current is greater than the third controllable current. Therefore, the control terminal voltage of the fourth switch tube M4 is pulled down, the fourth switch tube M4 is turned off, and the third branch current is not generated in the fifth resistor R5. Therefore, the first controllable current source G1 does not generate the first controllable current either, the output voltage VOUT begins to decrease, and the control terminal voltage of the second switch tube M2 also gradually decreases. When the control terminal voltage of the second switch tube M2 decreases to be less than the second power supply voltage VB, the circuit enters the next cycle.

[0070] Therefore, when the power supply circuit is in a stable working state, the voltage at the control terminal of the second switch tube M2 is exactly equal to the second power supply voltage VB, that is, , so at this time, the output voltage VOUT of the power supply circuit satisfies the following formula: .

[0071] Figure 3 FIG. 2 shows a schematic circuit structure diagram of a voltage generator according to an embodiment of the present application. Figure 3 As shown, the voltage generator includes a power supply branch. In the power supply branch, the external power supply voltage VIN is grounded in sequence through the fifth switch tube M5, the first transistor Q1, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the second transistor Q2, and the first transistor Q1 and the second transistor Q2 are both diode-connected. The first power supply end of the voltage generator is connected to the current output end of the fifth switch tube M5, and outputs the first power supply voltage VA. The second power supply end of the voltage generator is connected between the eighth resistor R8 and the ninth resistor R9, and outputs the second power supply voltage VB. The first power supply voltage VA satisfies the following formula: , the second power supply voltage VB satisfies the following formula: , wherein ID represents the power supply current generated in the power supply branch, VBE1 represents the voltage difference between the base and the emitter of the first transistor Q1, and VBE2 represents the voltage difference between the base and the emitter of the second transistor Q2. The circuit structure of the voltage generator of the embodiment of the present application can realize the output of two power supply voltages.

[0072] In a possible implementation, in the voltage generator, the external power supply voltage VIN is grounded through the first diode D1, the eleventh resistor R11, the third triode Q3 and the fifth controllable current source G5 in sequence. The base of the third triode Q3 is connected between the eighth resistor R8 and the ninth resistor R9. The voltage generator also includes a twelfth resistor R12 and a fourth triode Q4, one end of the twelfth resistor R12 is connected to the cathode of the first diode D1, the other end of the twelfth resistor R12 is connected to the collector of the fourth triode Q4, the emitter of the fourth triode Q4 is connected to the input end of the fifth controllable current source G5, and the base of the fourth triode Q4 is connected between the ninth resistor R9 and the tenth resistor R10.

[0073] In a possible implementation, the number ratio of the third transistor Q3 to the fourth transistor Q4 is 1: K. The parameters of the first transistor Q1 and the second transistor Q2 are the same.

[0074] In some possible implementations, in the voltage generator, the external power supply voltage VIN is also grounded through the sixth controllable current source G6, the sixth switch tube M6 and the second diode D2 in sequence. The voltage generator also includes a seventh switch tube M7, the current input end of the seventh switch tube M7 is connected to the external power supply voltage VIN, the current output end of the seventh switch tube M7 is connected between the eighth resistor R8 and the ninth resistor R9, and the control end of the seventh switch tube M7 is connected to the control end of the sixth switch tube M6 and is incorporated into the current input end of the sixth switch tube M6.

[0075] In a possible implementation, in the voltage generator, the external power supply voltage VIN is also grounded through the fifteenth resistor R15 and the tenth controllable current source G10 in sequence. The external power supply voltage VIN is also grounded through the second current source I2 and the sixteenth resistor R16 in sequence. The positive control terminal of the tenth controllable current source G10 is connected to the positive control terminal of the fifth controllable current source G5 and the end of the sixteenth resistor R16 close to the second current source I2, and the negative control terminal and output terminal of the tenth controllable current source G10 are both grounded. The negative control terminal and output terminal of the fifth controllable current source G5 are both grounded. The end of the fifteenth resistor R15 close to the tenth controllable current source G10 is connected to the negative control terminal of the sixth controllable current source G6, and the positive control terminal and input terminal of the sixth controllable current source G6 are both connected to the external power supply voltage VIN.

[0076] In the voltage generator, the working principle of the third transistor Q3 and the fourth transistor Q4 being turned on is as follows:

[0077] After the circuit is powered on, the second current source I2 generates a second current, so at this time, a voltage drop is generated across the sixteenth resistor R16, and the fifth controllable current source G5 and the tenth controllable current source G10 generate a fifth controllable current and a tenth controllable current according to the voltage drop. The tenth controllable current flows into the fifteenth resistor R15, a voltage drop is generated across the fifteenth resistor R15, and the sixth controllable current source G6 generates a sixth controllable current according to the voltage drop.

[0078] At this time, the external power supply voltage VIN pulls up the control terminal voltage of the sixth switch tube M6 and the seventh switch tube M7 through the sixth controllable current. At the same time, the current output terminal of the sixth switch tube M6 is grounded through the second diode D2. Therefore, since the external power supply voltage VIN is greater than the sum of the voltage difference VGS between the control terminal and the current output terminal of the sixth switch tube M6 and the forward conduction voltage drop VD2 of the second diode D2, at this time, the sixth switch tube M6 and the second diode D2 are both turned on. At this time, Figure 2 From the circuit structure shown, it can be obtained that the control terminal voltage of the sixth switch tube M6 and the control terminal voltage of the seventh switch tube M7 are both equal to VGS+VD2. Therefore, it can be obtained that when the current output terminal voltage of the seventh switch tube M7 is less than VD2, the seventh switch tube M7 is turned on, and the current output terminal voltage of the seventh switch tube M7 can be clamped at VD2. When the voltage at the current output terminal of the seventh switch tube M7 is greater than VD2, although the seventh switch tube M7 is not turned on, at this time, the base voltage of the third triode Q3 is greater than VD2. Therefore, in the present application, the base voltage of the third triode Q3 is at least VD2, and the base voltage of the fourth triode Q4 is at least close to VD2. Since the third triode Q3 and the fourth triode Q4 are grounded through the fifth controllable current source G5, the emitter voltage of the third triode Q3 and the emitter voltage of the fourth triode Q4 are pulled down to GND through the fifth controllable current. Therefore, at this time, when the base voltage of the third triode Q3 is at least VD2 and the base voltage of the fourth triode Q4 is at least close to VD2, the third triode Q3 and the fourth triode Q4 can be smoothly turned on. At the same time, in order to further ensure that the third transistor Q3 and the fourth transistor Q4 are smoothly turned on, M diodes can be connected in series in the branch of the fourth transistor Q4, thereby ensuring that the base voltage of the third transistor Q3 is approximately M×VD2 and the base voltage of the fourth transistor Q4 is close to M×VD2.

[0079] In some possible implementations, the external power supply voltage VIN is also connected to ground through the seventh controllable current source G7, the eighth switch tube M8 and the thirteenth resistor R13 in sequence, and the control end of the eighth switch tube M8 is connected to the collector of the third triode Q3. The external power supply voltage VIN is also connected to ground through the seventh controllable current source G7, the ninth switch tube M9 and the fourteenth resistor R14 in sequence, and the control end of the ninth switch tube M9 is connected to the collector of the fourth triode Q4. The positive control end and the input end of the seventh controllable current source G7 are both connected to the external power supply voltage VIN.

[0080] In some possible implementations, in the voltage generator, the external power supply voltage VIN is also connected to ground through the eighth controllable current source G8, the tenth switch tube M10 and the thirteenth resistor R13 in sequence. The external power supply voltage VIN is also connected to ground through the ninth controllable current source G9, the eleventh switch tube M11 and the fourteenth resistor R14 in sequence. The control ends of the tenth switch tube M10 and the eleventh switch tube M11 are connected and incorporated into the current input end of the tenth switch tube M10, and the current input end of the eleventh switch tube M11 is connected to the control end of the fifth switch tube M5. One end of the fifteenth resistor R15 close to the tenth controllable current source G10 is also connected to the negative control ends of the seventh controllable current source G7, the eighth controllable current source G8, and the ninth controllable current source G9. The positive control end and the input end of the eighth controllable current source G8 are both connected to the external power supply voltage VIN, and the positive control end and the input end of the ninth controllable current source G9 are both connected to the external power supply voltage VIN. In a possible implementation, the eleventh resistor R11 and the twelfth resistor R12 have the same resistance value, and the thirteenth resistor R13 and the fourteenth resistor R14 have the same resistance value.

[0081] The working principle of the voltage generator is as follows:

[0082] In this embodiment, during the conduction of the third transistor Q3 and the fourth transistor Q4, after the circuit is powered on, a voltage drop is generated across the fifteenth resistor R15. In addition to the sixth controllable current source G6 generating a sixth controllable current according to the voltage drop, the seventh controllable current source G7, the eighth controllable current source G8 and the ninth controllable current source G9 respectively generate a seventh controllable current, an eighth controllable current and a ninth controllable current according to the voltage drop.

[0083] After the third transistor Q3 and the fourth transistor Q4 are turned on, the cathode of the first diode D1 is pulled down, and the first diode D1 is turned on, so current flows through the third transistor Q3 and the fourth transistor Q4. At this time, since the ratio of the number of the third transistor Q3 to the number of the fourth transistor Q4 is 1:K, and when the circuit is just powered on, the base voltage of the third transistor Q3 and the base voltage of the fourth transistor Q4 are very small, at this time, the number ratio of the transistors has a greater impact on the current flowing through the transistors, so the current IC3 flowing through the third transistor Q3 is less than the current IC4 flowing through the fourth transistor Q4. Since the eleventh resistor R11 and the twelfth resistor R12 have the same resistance value, the voltage drop across the eleventh resistor R11 is smaller than the voltage drop across the twelfth resistor R12. Since the eleventh resistor R11 is connected to one end of the twelfth resistor R12, it can be obtained that the control terminal voltage of the eighth switch tube M8 connected to the eleventh resistor R11 is greater than the control terminal voltage of the ninth switch tube M9 connected to the twelfth resistor R12. Since the eighth switch tube M8 is connected to the current input terminal of the ninth switch tube M9, the voltage difference between the current input terminal and the control terminal of the eighth switch tube M8 is smaller than that of the ninth switch tube M9. The voltage difference between the current input terminal and the control terminal of the switch tube M9 is, therefore, the current flowing through the ninth switch tube M9 is greater than the current flowing through the eighth switch tube M8. At this time, since the resistance values ​​of the thirteenth resistor R13 and the fourteenth resistor R14 are equal, it can be obtained that the voltage drop across the fourteenth resistor R14 is greater than the voltage drop across the thirteenth resistor R13. Therefore, the voltage at the current output terminal of the tenth switch tube M10 is less than the voltage at the current output terminal of the eleventh switch tube M11. The tenth switch tube M10 is connected to the control terminal of the eleventh switch tube M11. Therefore, the control terminal of the eleventh switch tube M11 is connected to the current The voltage difference between the output ends is smaller than the voltage difference between the control end and the current output end of the tenth switch tube M10, so that the current flowing through the tenth switch tube M10 is greater than the current flowing through the eleventh switch tube M11. Since the eighth controllable current is equal to the ninth controllable current, it can be obtained that the current flowing into the point C between the ninth controllable current source G9 and the eleventh switch tube M11 is equal to the ninth controllable current and equal to the current flowing through the tenth switch tube M10. The current flowing out of the point C is equal to the current flowing through the eleventh switch tube M11. Therefore, the current flowing into the point C is greater than the current flowing out of the point C. The voltage at point C is pulled up, that is, the voltage at the control end of the fifth switch tube M5 is pulled up to the external power supply voltage VIN. At the same time, the current output end of the fifth switch tube M5 is grounded through the first transistor Q1, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the second transistor Q2. The external power supply voltage VIN is obviously much larger than the voltage difference VBE between the base and the emitter of the first transistor Q1, the voltage difference VBE between the base and the emitter of the second transistor Q2, and the voltage difference VGS between the control end and the current output end of the fifth switch tube M5. Therefore, the fifth switch tube M5 is turned on.At this time, a power supply current ID is generated in the branch composed of the fifth switch tube M5, the first transistor Q1, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the second transistor Q2. As the power supply current ID increases, the base voltage of the third transistor Q3 and the base voltage of the fourth transistor Q4 both gradually increase. Since the voltage drop across the ninth resistor R9 increases, the base voltage of the third transistor Q3 increases relative to the base voltage of the fourth transistor Q4. Therefore, the voltage difference VBE3 between the base and the emitter of the third transistor Q3 increases relative to the voltage difference VBE4 between the base and the emitter of the fourth transistor Q4. In addition, the influence of the voltage difference between the base and the emitter of the transistor on the current is greater than the influence of the number of transistors connected in parallel on the current. Therefore, it can be obtained that as the power supply current ID increases, the current IC3 flowing through the third transistor Q3 gradually becomes greater than the current IC3 flowing through the fourth transistor Q4. The current IC4 flows through. At this time, combined with the above analysis, it can be seen that the current flowing into C is less than the current flowing out from point C, and the voltage at point C is pulled down, that is, the voltage at the control end of the fifth switch tube M5 is pulled down. At this time, by designing the parameters of the fourteenth resistor R14 and the current flowing through the eleventh switch tube M11, the terminal voltage of the fourteenth resistor R14 is lower than the voltage difference VBE between the base and the emitter of the first transistor Q1 plus the voltage difference VBE between the base and the emitter of the second transistor Q2 plus the voltage difference VGS between the control end and the current output end of the fifth switch tube M5. Therefore, when the voltage at point C is pulled down, the fifth switch tube M5 is turned off, the power supply current ID is reduced, and the base voltage of the third transistor Q3 and the base voltage of the fourth transistor Q4 are both reduced. Afterwards, when the current IC3 flowing through the third transistor Q3 is less than the current IC4 flowing through the fourth transistor Q4, the circuit enters the next cycle.

[0084] When the voltage generator enters a stable working state, the current IC3 flowing through the third transistor Q3 is equal to the current IC4 flowing through the fourth transistor Q4. At the same time, from the circuit structure of the voltage generator, it can be seen that VBE3=VBE4+VR9, where VR9 is the voltage difference across the ninth resistor R9, and VR9=ID×R9. At this time, combined with the transistor current formula, it can be obtained: , it can be seen that the supply current ID satisfies the following formula: , where Vt is the thermal voltage and R9 is the resistance of the ninth resistor.

[0085] From the above analysis, it can be seen that the first supply voltage VA output by the voltage generator satisfies the following formula: , the output second supply voltage VB satisfies the following formula: Since the parameters of the first transistor Q1 and the second transistor Q2 are the same, VBE1 of the first transistor Q1 is equal to VBE2 of the second transistor Q2, denoted as VBE, so we can get, In addition, since the VBE of the transistor is a negative temperature parameter and the thermal voltage Vt of the transistor is a positive temperature parameter, by appropriately matching the parameters of K, R8, R9 and R10, the output first power supply voltage VA and the second power supply voltage VB can be made unaffected by temperature, so that the voltage generator generates two high-precision power supply voltages that are unaffected by temperature and have the same accuracy.

[0086] According to the scheme of the embodiment of the present application, when the voltage generator is just powered on, the current in the third transistor Q3 and the fourth transistor Q4 is small, so at this time, the voltage drop across the eleventh resistor R11 and the twelfth resistor R12 is small. At this time, if the first diode D1 does not exist, the eleventh resistor R11 and the twelfth resistor R12 are directly connected to the external power supply voltage VIN, then the terminal voltage of the eleventh resistor R11 and the twelfth resistor R12 away from the external power supply voltage VIN will be larger, close to the external power supply voltage VIN, thereby causing the control terminal voltage of the eighth switch tube M8 and the ninth switch tube M9 to be larger, making the eighth switch tube M8 and the ninth switch tube M9 unable to conduct. Therefore, at this time, the first diode D1 is set in the voltage generator, so that the terminal voltage of the eleventh resistor R11 and the twelfth resistor R12 close to the external power supply voltage VIN is VIN-VD1, where VD1 is the forward conduction voltage drop of the first diode D1. And by Figure 2 It can be seen that the seventh controllable current pulls up the current input terminal voltage of the eighth switch tube M8 and the ninth switch tube M9 to the external power supply voltage VIN, so when the control terminal voltage of the eighth switch tube M8 and the ninth switch tube M9 is less than VIN-VGS, they can be smoothly turned on. In addition, it can be known from the prior art that the forward conduction voltage drop of the diode is slightly less than the gate-source voltage difference VGS after the MOS tube is turned on, so when the first diode D1, the eleventh resistor R11 and the twelfth resistor R12 are set in the circuit, it can be basically ensured that the eleventh resistor R11 and the twelfth resistor R12 are far away from the terminal voltage of the external power supply voltage VIN, that is, the control terminal voltage of the eighth switch tube M8 and the ninth switch tube M9 is less than VIN-VGS, so that the eighth switch tube M8 and the ninth switch tube M9 are smoothly turned on.

[0087] At the same time, in order to further ensure that the eighth switch tube M8 and the ninth switch tube M9 are smoothly turned on, N diodes can be connected in series in the branch of the first diode D1 to ensure that the control terminal voltage of the eighth switch tube M8 and the ninth switch tube M9 is less than VIN-VGS.

[0088] Furthermore, when the voltage generator enters a stable working state, the first supply voltage VB output by the voltage generator is greater than VGS, thereby ensuring that the seventh switch tube M7 is in an off state and will not affect the magnitudes of the two supply voltages output by the voltage generator.

[0089] In addition, the first power supply end of the voltage generator is connected to the external power supply voltage end through the fifth switch tube M5, and the current output by the first power supply end to the voltage regulator comes from the external power supply voltage end, and the current output to the voltage regulator does not affect the magnitude of the power supply current ID, so the first power supply end has current capacity. The second power supply end is connected to the external power supply voltage end through the eighth resistor R8, the first transistor Q1 and the fifth switch tube M5. Since the ninth resistor R9, the tenth resistor R10 and the second transistor Q2 are regulated by the circuit, the current flowing through the above three devices remains unchanged. Therefore, at this time, if the second power supply end outputs current to the voltage regulator, the power supply current ID will inevitably increase, thereby making the first power supply voltage VA too large, so the second power supply end does not have current capacity.

[0090] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A power supply circuit for improving output voltage accuracy, characterized in that: It includes a voltage generator and a voltage regulator, wherein the voltage generator is connected to an external power supply voltage VIN and outputs a first power supply voltage VA and a second power supply voltage VB; In the voltage regulator, the external power supply voltage VIN is grounded through the first controllable current source G1, the first resistor R1 and the second resistor R2 in sequence; the first power supply voltage VA is grounded through the current source module, the first switch tube M1 and the third resistor R3 in sequence; the first power supply voltage VA is also grounded through the current source module, the second switch tube M2 and the fourth resistor R4 in sequence, and the voltage regulator includes a control module, the external power supply voltage VIN is connected to the control module, and the control module is connected to the current output end of the first switch tube M1, the current source module, the first controllable current source G1 and the ground end; The control end of the first switch tube M1 is connected to the second power supply voltage VB, the control end of the second switch tube M2 is connected between the first resistor R1 and the second resistor R2, the output end of the power supply circuit is connected between the first controllable current source G1 and the first resistor R1, the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal, and the control module is used to control the current flowing through the first switch tube M1 to be equal to the current flowing through the second switch tube M2, so that the control end voltage of the second switch tube M2 is equal to the control end voltage of the first switch tube M1; The voltage regulator further includes a third switch tube M3, and a control end of the third switch tube M3 is connected to the first power supply voltage VA; The voltage generator includes a power supply branch, in which the external power supply voltage VIN is connected to ground in sequence through a fifth switch tube M5, a first transistor Q1, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a second transistor Q2, and the first transistor Q1 and the second transistor Q2 are both connected in a diode manner; The first power supply end of the voltage generator is connected to the current output end of the fifth switch tube M5, and outputs the first power supply voltage VA, and the second power supply end of the voltage generator is connected between the eighth resistor R8 and the ninth resistor R9, and outputs the second power supply voltage VB; The first supply voltage VA and the second supply voltage VB are two supply voltages that are not affected by temperature and have the same accuracy.

2. The power supply circuit according to claim 1, characterized in that: When the voltage regulator is in a stable working state, the control terminal voltage of the second switch tube M2 is equal to the second power supply voltage VB, so that the output terminal voltage VOUT of the power supply circuit satisfies the following formula: 。 3. The power supply circuit according to claim 2, characterized in that: In the control module, the external power supply voltage VIN is also connected to ground via a fifth resistor R5, a fourth switch tube M4 and a sixth resistor R6 in sequence; The negative control terminal of the first controllable current source G1 is connected to one end of the fifth resistor R5 close to the fourth switch tube M4 , and the positive control terminal and the input terminal of the first controllable current source G1 are both connected to the external power supply voltage VIN.

4. The power supply circuit according to claim 3, characterized in that: The current source module comprises: A second controllable current source G2, whose positive control terminal and input terminal are both connected to the first power supply voltage VA, and whose output terminal is connected to the current input terminals of the first switch tube M1 and the second switch tube M2; a third controllable current source G3, whose positive control terminal and input terminal are both connected to the first power supply voltage VA, whose negative control terminal is connected to the negative control terminal of the second controllable current source G2, and whose output terminal is connected to the control terminal of the fourth switch tube M4; The control module includes a fourth controllable current source G4, a positive control end of the fourth controllable current source G4 is connected to the current output end of the first switch tube M1, an input end is connected to the output end of the third controllable current source G3 and the control end of the fourth switch tube M4, and a negative control end and an output end are both grounded.

5. The power supply circuit according to claim 4, characterized in that: In the current source module, the first supply voltage VA is also grounded via the seventh resistor R7 and the first current source I1 in sequence; One end of the seventh resistor R7 close to the first current source I1 is connected to the negative control end of the second controllable current source G2.

6. The power supply circuit according to claim 5, characterized in that: The current input terminal of the third switch tube M3 is connected to the negative control terminal of the first controllable current source G1 , and the current output terminal of the third switch tube M3 is connected to the current input terminal of the fourth switch tube M4 .

7. The power supply circuit according to any one of claims 1 to 6, characterized in that: The first power supply voltage VA is greater than the second power supply voltage VB, and a difference between the first power supply voltage VA and the second power supply voltage VB is greater than or equal to a turn-on threshold voltage of the switch tube.

8. The power supply circuit according to any one of claims 4 to 6, characterized in that: The ratio of the controllable current generated by the second controllable current source G2 to the controllable current generated by the third controllable current source G3 is 2:1; The second controllable current source G2, the first switch tube M1 and the third resistor R3 form a first branch, and the ratio of the current of the first branch to the controllable current generated by the fourth controllable current source G4 is 1:

1.

9. The power supply circuit according to any one of claims 1 to 6, characterized in that: The first supply voltage VA satisfies the following formula: ； The second supply voltage VB satisfies the following formula: ； Wherein, ID represents the power supply current generated in the power supply branch, VBE1 represents the voltage difference between the base and the emitter of the first transistor Q1, and VBE2 represents the voltage difference between the base and the emitter of the second transistor Q2.

10. The power supply circuit according to claim 9, characterized in that: In the voltage generator, the external power supply voltage VIN is grounded through the first diode D1, the eleventh resistor R11, the third transistor Q3 and the fifth controllable current source G5 in sequence, and the base of the third transistor Q3 is connected between the eighth resistor R8 and the ninth resistor R9; The voltage generator also includes a twelfth resistor R12 and a fourth transistor Q4, one end of the twelfth resistor R12 is connected to the cathode of the first diode D1, the other end of the twelfth resistor R12 is connected to the collector of the fourth transistor Q4, the emitter of the fourth transistor Q4 is connected to the input end of the fifth controllable current source G5, and the base of the fourth transistor Q4 is connected between the ninth resistor R9 and the tenth resistor R10.

11. The power supply circuit according to claim 10, characterized in that: The number ratio of the third transistor Q3 to the fourth transistor Q4 is 1:K; The parameters of the first transistor Q1 and the second transistor Q2 are the same.

12. The power supply circuit according to claim 11, characterized in that: The first supply voltage VA satisfies the following formula: ； The second supply voltage VB satisfies the following formula: ； Wherein, VBE represents the voltage difference between the base and the emitter of the first transistor Q1 and the second transistor Q2, and Vt represents the thermal voltage of the transistor.

13. The power supply circuit according to claim 12, characterized in that: In the voltage generator, the external power supply voltage VIN is also grounded via a sixth controllable current source G6, a sixth switch tube M6 and a second diode D2 in sequence; The voltage generator further includes a seventh switch tube M7, a current input end of the seventh switch tube M7 is connected to the external power supply voltage VIN, a current output end of the seventh switch tube M7 is connected between the eighth resistor R8 and the ninth resistor R9, and a control end of the seventh switch tube M7 is connected to the control end of the sixth switch tube M6 and is incorporated into the current input end of the sixth switch tube M6; When the voltage at the current output terminal of the seventh switch tube M7 is less than the forward conduction voltage drop VD2 of the second diode D2, the seventh switch tube M7 is turned on, thereby clamping the voltage at the current output terminal of the seventh switch tube M7 at VD2; when the voltage at the current output terminal of the seventh switch tube M7 is greater than VD2, the voltage difference between the base and the emitter of the third transistor Q3 and the fourth transistor Q4 is greater than the forward conduction voltage drop of the transistor, thereby ensuring that the third transistor Q3 and the fourth transistor Q4 are smoothly turned on.

14. The power supply circuit according to claim 13, characterized in that: There are multiple second diodes D2, and the multiple second diodes D2 are connected in series.

15. The power supply circuit according to claim 13 or 14, characterized in that: In the voltage generator, the external power supply voltage VIN is also grounded through the seventh controllable current source G7, the eighth switch tube M8 and the thirteenth resistor R13 in sequence, and the control end of the eighth switch tube M8 is connected to the collector of the third triode Q3; the external power supply voltage VIN is also grounded through the seventh controllable current source G7, the ninth switch tube M9 and the fourteenth resistor R14 in sequence, and the control end of the ninth switch tube M9 is connected to the collector of the fourth triode Q4.

16. The power supply circuit according to claim 15, characterized in that: In the voltage generator, the external power supply voltage VIN is also grounded through the eighth controllable current source G8, the tenth switch tube M10 and the thirteenth resistor R13 in sequence; the external power supply voltage VIN is also grounded through the ninth controllable current source G9, the eleventh switch tube M11 and the fourteenth resistor R14 in sequence; The control ends of the tenth switch tube M10 and the eleventh switch tube M11 are connected and merged into the current input end of the tenth switch tube M10 , and the current input end of the eleventh switch tube M11 is connected to the control end of the fifth switch tube M5 .

17. The power supply circuit according to claim 16, characterized in that: The resistance values ​​of the eleventh resistor R11 and the twelfth resistor R12 are equal; The resistance values ​​of the thirteenth resistor R13 and the fourteenth resistor R14 are equal.

18. The power supply circuit according to claim 16 or 17, characterized in that: In the voltage generator, the external power supply voltage VIN is also connected to ground via a fifteenth resistor R15 and a tenth controllable current source G10 in sequence; the external power supply voltage VIN is also connected to ground via a second current source I2 and a sixteenth resistor R16 in sequence; The positive control terminal of the tenth controllable current source G10 is connected to the positive control terminal of the fifth controllable current source G5 and the end of the sixteenth resistor R16 close to the second current source I2, the negative control terminal and the output terminal of the tenth controllable current source G10 are both grounded, the end of the fifteenth resistor R15 close to the tenth controllable current source G10 is connected to the negative control terminals of the seventh controllable current source G7, the eighth controllable current source G8, the ninth controllable current source G9 and the sixth controllable current source G6, the negative control terminal of the fifth controllable current source G5 is grounded, and the positive control terminals and input terminals of the sixth controllable current source G6, the seventh controllable current source G7, the eighth controllable current source G8 and the ninth controllable current source G9 are all connected to the external power supply voltage VIN.

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