Anti-radiation voltage pre-stabilizing circuit with wide power supply voltage range

Abstract

The invention discloses an anti-radiation pre-voltage-stabilizing circuit with a wide power supply voltage range, and the circuit comprises a bias circuit which comprises a first current mirror and an emitter junction reference current source, the input end of the first current mirror is electrically connected with a power supply VCC, the output end of the first current mirror is connected with the input end of the voltage reference source, and the first current mirror is used for outputting stable bias current; the emitter junction reference current source is used for generating reference current; the voltage reference source comprises a temperature compensation circuit and a band gap core circuit, the input end of the temperature compensation circuit is electrically connected with the output end of the first current mirror, and the temperature compensation circuit is used for generating temperature compensation voltage; the input end of the band-gap core circuit is electrically connected with the output end of the temperature compensation circuit and is used for generating reference voltage; and the input end of the output buffer circuit is connected with the reference voltage, and the output buffer circuit is used for buffering and driving the reference voltage. According to the invention, stable internal working voltage can be provided for a chip with a wide power supply voltage input range in a radiation environment, and the circuit is suitable for the design of a pre-voltage-stabilizing circuit of a bipolar process.

Description

Technical Field

[0001] This invention relates to the field of analog integrated circuit technology, and in particular to a radiation-resistant pre-regulatory circuit with a wide power supply voltage range. Background Technology

[0002] Voltage regulator circuits are fundamental modules in integrated circuits, providing stable operating voltage and current to other modules within the chip. In bipolar integrated circuits, the traditional method often utilizes the reverse breakdown characteristic of the emitter junction of an NPN transistor to form a Zener diode, which serves as the reference voltage source for the pre-regulator circuit, such as... Figure 1 As shown. However, this Zener diode solution reveals several inherent defects during long-term operation or in harsh environments, resulting in limited reliability: Insufficient temperature stability: Zener diodes have a high positive temperature coefficient of breakdown voltage (typically +2mV / °C or higher), causing their output voltage to drift significantly with changes in ambient temperature. Temperature fluctuations are common in integrated circuit applications (e.g., power consumption variations or external thermal effects), but Zener diodes lack effective temperature compensation mechanisms. This results in an unstable reference voltage, affecting the overall chip accuracy, especially when operating over a wide temperature range, where voltage drift can accumulate to unacceptable levels (e.g., exceeding 5%), limiting the circuit's application in high-precision analog systems.

[0003] Poor long-term reliability and susceptibility to aging effects: After undergoing accelerated life testing such as aging and temperature cycling, Zener diodes exhibit "Zener creep," an irreversible drift in breakdown voltage over time. This drift typically originates from defect migration or interface state changes in the semiconductor material, and the drift magnitude can reach several tenths (e.g., 10%-30%), intensifying after prolonged operation. Current technology lacks anti-aging design for Zener diodes, potentially causing chip failure in the middle of their lifespan, failing to meet the demands of long-life applications such as automotive electronics or industrial control.

[0004] Weak radiation resistance: Under total dose (TID) radiation, the breakdown characteristics of Zener diodes degrade due to radiation-induced charge trapping, leading to exacerbated voltage regulation drift. Existing solutions lack integrated radiation hardening measures, causing a sharp drop in reference voltage stability in radiation scenarios such as aerospace or nuclear industries. The drift amplitude may far exceed that under normal conditions, resulting in chip malfunction. This sensitivity limits the use of Zener diodes in high-reliability applications.

[0005] Low voltage accuracy and consistency: The breakdown voltage of Zener diodes is significantly affected by process variations, resulting in high initial value dispersion between different batches or chips. Current technology lacks precise voltage adjustment or compensation mechanisms, leading to large output fluctuations in the pre-regulator circuit, making it difficult to meet the low noise and high consistency requirements of modern integrated circuits. Furthermore, Zener diodes have high dynamic impedance, which easily introduces additional errors when the load changes. Summary of the Invention

[0006] To address the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a radiation-resistant pre-regulatory circuit with a wide power supply voltage range, which can provide a stable internal operating voltage for chips with a wide power supply voltage input range under radiation environment, and is suitable for pre-regulatory circuit design in bipolar processes.

[0007] One technical solution adopted by this invention is to provide a radiation-resistant pre-regulatory circuit with a wide power supply voltage range, comprising: a bias circuit, a voltage reference source, and an output buffer circuit, wherein, The bias circuit includes a first current mirror and an emitter junction reference current source. The input terminal of the first current mirror is electrically connected to the power supply VCC, and its output terminal is connected to the input terminal of the voltage reference source to output a stable bias current. The emitter junction reference current source is used to generate a reference current that is almost independent of the power supply voltage. The voltage reference source includes a temperature compensation circuit and a bandgap core circuit. The input terminal of the temperature compensation circuit is electrically connected to the output terminal of the first current mirror to generate a temperature compensation voltage. The input terminal of the bandgap core circuit is electrically connected to the output terminal of the temperature compensation circuit to generate a reference voltage. An output buffer circuit is provided, with its input terminal connected to the reference voltage, for buffering and driving the reference voltage.

[0008] Furthermore, the first current mirror includes a first transistor Q1 and a second transistor Q2. Both the first transistor Q1 and the second transistor Q2 are PNP transistors. The base of the first transistor Q1 is electrically connected to the base of the second transistor Q2. The emitters of both the first transistor Q1 and the second transistor Q2 are electrically connected to the power supply VCC. The base and collector of the first transistor Q1 are short-circuited.

[0009] Furthermore, the bias feedback loop includes a first resistor R1, a second resistor R2, a twelfth transistor Q12, and a thirteenth transistor Q13, wherein the twelfth transistor Q12 and the thirteenth transistor Q13 are both NPN transistors; the first end of the first resistor R1 is electrically connected to the emitter of the first transistor Q1, and the second end is electrically connected to the base of the twelfth transistor Q12 and the collector of the thirteenth transistor Q13; the first end of the second resistor R2 is electrically connected to the emitter of the twelfth transistor Q12 and the base of the thirteenth transistor Q13, and the second end is electrically connected to the emitter of the thirteenth transistor Q13 and grounded; the collector of the twelfth transistor Q12 is electrically connected to the base of the first transistor Q1.

[0010] Furthermore, the temperature compensation circuit includes several NPN transistors whose emitters and collectors are connected in sequence, and whose bases and collectors are short-circuited.

[0011] Furthermore, the temperature compensation circuit includes a third transistor Q3, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, and an eighth transistor Q8; the bases of the third transistor Q3, the fifth transistor Q5, the sixth transistor Q6, the seventh transistor Q7, and the eighth transistor Q8 are all shorted to their own collectors; the collector of the third transistor Q3 is connected to the bias current of the first current mirror, and its emitter is electrically connected to the collector of the fifth transistor Q5; the emitter of the fifth transistor Q5 is electrically connected to the collector of the sixth transistor Q6; the emitter of the sixth transistor Q6 is electrically connected to the collector of the seventh transistor Q7; the emitter of the seventh transistor Q7 is electrically connected to the collector of the eighth transistor Q8; and the emitter of the eighth transistor Q8 outputs the reference voltage.

[0012] Furthermore, the bandgap core circuit includes a ninth transistor Q9, a thirteenth transistor Q10, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The ninth transistor Q9 and the thirteenth transistor Q10 are both NPN transistors, and their bases are electrically connected to form a second current mirror. The base and collector of the ninth transistor Q9 are short-circuited, and its emitter is grounded. The first end of the third resistor R3 is electrically connected to the emitter of the eighth transistor Q8, and its second end is electrically connected to the collector of the ninth transistor Q9. The first end of the fourth resistor R4 is electrically connected to the emitter of the eighth transistor Q8, and its second end is electrically connected to the collector of the thirteenth transistor Q10. The first end of the fifth resistor R5 is electrically connected to the emitter of the thirteenth transistor Q10, and its second end is grounded.

[0013] Furthermore, the emitter area ratio of the ninth transistor Q9 and the thirteenth transistor Q10 is 1:4; the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal.

[0014] Furthermore, the emitter area ratio of the fifth transistor Q5, the sixth transistor Q6, the seventh transistor Q7, and the eighth transistor Q8 to that of the ninth transistor Q9 is 2:1.

[0015] Furthermore, the voltage reference source also includes an eleventh transistor Q11 as a reference voltage output interface; the base of the eleventh transistor Q11 is electrically connected to the second terminal of the fourth resistor R4 and the collector of the thirteenth transistor Q10; the emitter of the eleventh transistor Q11 is grounded; and the collector of the eleventh transistor Q11 is electrically connected to the base of the third transistor Q3.

[0016] Furthermore, the output buffer circuit includes a fourth transistor Q4 and a sixth resistor R6. The fourth transistor Q4 is an NPN transistor. The collector of the fourth transistor Q4 is electrically connected to the power supply VCC, the emitter is connected to the voltage output Vout, and the base is electrically connected to the output terminal of the voltage reference source. The first terminal of the sixth resistor R6 is electrically connected to the emitter of the fourth transistor Q4, and the second terminal is grounded.

[0017] The wide power supply voltage range radiation-resistant pre-regulator circuit of the present invention has at least the following beneficial effects: The bias circuit provides a stable base, the voltage reference source generates a high-precision reference voltage, and the output buffer ensures reliable voltage output. Overall, the circuit has advantages such as low temperature drift, high reliability, and strong anti-interference, making it suitable for harsh environments such as high-precision analog systems, automotive electronics, or aerospace. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a diagram of a pre-regulated voltage circuit in the prior art.

[0019] Figure 2 This is a diagram of a radiation-resistant pre-stabilized circuit with a wide power supply voltage range according to the present invention. Detailed Implementation

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Please see Figure 1This is a diagram of a pre-regulated voltage circuit in the prior art. It can be seen that the pre-regulated voltage circuit in the prior art has the following obvious problems: 1. Lack of temperature compensation mechanism (such as PTAT voltage generation), failing to combine the positive temperature coefficient voltage with the negative temperature coefficient Vbe to achieve a near-zero temperature coefficient output; 2. Simple bias circuit (relying solely on R1 to set the current), lacking feedback regulation or current mirror structure to suppress power supply noise, resulting in weak anti-interference capability compared to advanced circuits using current mirrors and feedback loops; 3. Lack of buffer or feedback control in the output stage, unable to compensate for load changes in real time; 4. Simple design, lacking anti-aging structures (such as bandgap cores) or radiation hardening measures; 5. Crude current source design, lacking temperature compensation resistors or current mirror matching technology.

[0022] Compared to the pre-regulator circuit in the prior art described above, please refer to [link / reference]. Figure 2 This is a radiation-resistant pre-regulatory circuit diagram for a wide power supply voltage range according to the present invention. The circuit may include: a bias circuit, a voltage reference source, and an output buffer circuit, wherein... The bias circuit includes a first current mirror and an emitter junction reference current source. The input terminal of the first current mirror is electrically connected to the power supply VCC, and its output terminal is connected to the input terminal of the voltage reference source to output a stable bias current. The emitter junction reference current source is used to generate a reference current that is almost independent of the power supply voltage. This bias circuit provides a stable bias current for the entire system, ensuring that other parts operate at their ideal operating points and reducing power supply fluctuations and environmental influences.

[0023] The aforementioned first current mirror may specifically include a first transistor Q1 and a second transistor Q2. Both the first transistor Q1 and the second transistor Q2 are PNP transistors. The base of the first transistor Q1 is electrically connected to the base of the second transistor Q2, and the emitters of both transistors are electrically connected to the power supply VCC. The base and collector of the first transistor Q1 are short-circuited. This first current mirror, through its current mirror structure, can ensure precise matching of the bias current, reduce the impact of process deviations, and improve circuit consistency. Furthermore, since the current mirror is insensitive to changes in power supply voltage, it can effectively suppress errors caused by VCC fluctuations, enhancing the circuit's anti-interference capability. In addition, the characteristics of PNP transistors help compensate for temperature changes, keeping the bias current stable over a wide temperature range, providing a reliable basis for the voltage reference source.

[0024] The aforementioned emitter junction reference current source may include a first resistor R1, a second resistor R2, a twelfth transistor Q12, and a thirteenth transistor Q13, wherein the twelfth transistor Q12 and the thirteenth transistor Q13 are both NPN transistors; the first end of the first resistor R1 is electrically connected to the emitter of the first transistor Q1, and the second end is electrically connected to the base of the twelfth transistor Q12 and the collector of the thirteenth transistor Q13; the first end of the second resistor R2 is electrically connected to the emitter of the twelfth transistor Q12 and the base of the thirteenth transistor Q13, and the second end is electrically connected to the emitter of the thirteenth transistor Q13 and grounded; the collector of the twelfth transistor Q12 is electrically connected to the base of the first transistor Q1. This emitter-base reference current source uses the base-emitter voltage of the thirteenth transistor Q13 as a reference to generate a reference bias current across the second resistor R2 that is almost independent of the power supply voltage. At the same time, the bias current is stabilized through a negative feedback loop (Q12 and Q13 form a feedback structure). The feedback gain is set through the first resistor R1 and the second resistor R2 to reduce the influence of transistor parameter dispersion and improve circuit stability.

[0025] The voltage reference source includes a temperature compensation circuit and a bandgap core circuit. The input terminal of the temperature compensation circuit is electrically connected to the output terminal of the first current mirror to generate a temperature compensation voltage. The input terminal of the bandgap core circuit is electrically connected to the output terminal of the temperature compensation circuit to generate a reference voltage. This voltage reference source is the core of this circuit, generating a reference voltage with a low temperature coefficient and high stability, which directly determines the overall performance.

[0026] The temperature compensation circuit may include several NPN transistors whose emitters and collectors are connected in sequence, with their bases and collectors shorted. This temperature compensation circuit uses multiple NPN transistors connected in series (the emitter of one transistor is connected to the collector of the next), and shorts the base and collector of each transistor to form an equivalent diode, thereby generating a voltage inversely proportional to the absolute temperature. Furthermore, because the transistor structure is more stable than a Zener diode, it is less prone to Zener creep, exhibiting minimal voltage drift after long-term operation or aging, thus extending chip lifespan. In addition, using standard bipolar transistors eliminates the need for special components, reducing costs and improving manufacturability.

[0027] This temperature compensation circuit specifically includes a third transistor Q3, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, and an eighth transistor Q8. The bases of all transistors Q3, Q5, Q6, Q7, and Q8 are shorted to their collectors. The collector of the third transistor Q3 is connected to the bias current of the first current mirror, and its emitter is electrically connected to the collector of the fifth transistor Q5. The emitter of the fifth transistor Q5 is electrically connected to the collector of the sixth transistor Q6. The emitter of the sixth transistor Q6 is electrically connected to the collector of the seventh transistor Q7. The emitter of the seventh transistor Q7 is electrically connected to the collector of the eighth transistor Q8. The emitter of the eighth transistor Q8 outputs the reference voltage.

[0028] The aforementioned bandgap core circuit may specifically include a ninth transistor Q9, a thirteenth transistor Q10, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. Specifically, the ninth transistor Q9 and the thirteenth transistor Q10 are both NPN transistors, with their bases electrically connected to form a second current mirror. The base and collector of the ninth transistor Q9 are short-circuited, and its emitter is grounded. The first end of the third resistor R3 is electrically connected to the emitter of an eighth transistor Q8, and its second end is electrically connected to the collector of the ninth transistor Q9. The first end of the fourth resistor R4 is electrically connected to the emitter of the eighth transistor Q8, and its second end is electrically connected to the collector of the thirteenth transistor Q10. The first end of the fifth resistor R5 is electrically connected to the emitter of the thirteenth transistor Q10, and its second end is grounded. This bandgap core circuit combines the PTAT voltage and Vbe voltage, and generates a reference voltage through a second current mirror and resistor network composed of the ninth transistor Q9 and the thirteenth transistor Q10.

[0029] To precisely control the output voltage, the emitter area of ​​each transistor in the bandgap core circuit can be set. For example, if the emitter area ratio of the ninth transistor Q9 and the thirteenth transistor Q10 is set to 1:4, and the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal, then the current flowing through the ninth transistor Q9 and the thirteenth transistor Q10 is equal. The current generated across R5 due to the voltage difference between the emitter junctions of the ninth transistor Q9 and the thirteenth transistor Q10 is: .in, This refers to thermal voltage, which is a voltage proportional to absolute temperature (i.e., PTAT voltage).

[0030] Furthermore, the emitter area ratio of transistors Q5, Q6, Q7, and Q8 to that of transistor Q9 can be set to 2:1. Therefore, their current is also twice that of transistor Q9. Consequently, the emitter junction voltages of Q5~Q8 are the same as those of Q9, and the voltage at point A is: By using a base-emitter voltage with a negative temperature coefficient ( ) and voltage difference with a positive temperature coefficient ( By combining these two methods, temperature compensation can be achieved using the bandgap reference principle.

[0031] Therefore, the output voltage regulation can be obtained as follows: .in, This represents the emitter voltage of the third transistor Q3, which is also the voltage at point A. This represents the base-emitter voltage of the third transistor Q3. This represents the base-emitter voltage of the fourth transistor Q4. The collector current ratio of the third transistor Q3 and the fourth transistor Q4 in this circuit determines their emitter areas. ,final This ensures that the output voltage Vout remains almost unchanged with temperature, achieving voltage regulation.

[0032] This voltage reference source may also include an eleventh transistor Q11 as a reference voltage output interface; the base of the eleventh transistor Q11 is electrically connected to the second terminal of the fourth resistor R4 and the collector of the thirteenth transistor Q10; the emitter of the eleventh transistor Q11 is grounded; and the collector of the eleventh transistor Q11 is electrically connected to the base of the third transistor Q3. This eleventh transistor Q11 can be used to buffer and drive the reference voltage, isolating the load from its influence.

[0033] An output buffer circuit, whose input is connected to the reference voltage, is used to buffer and drive the reference voltage. This output buffer section ensures that the reference voltage can stably drive the external load without introducing additional errors.

[0034] This output buffer circuit may specifically include a fourth transistor Q4 and a sixth resistor R6. The fourth transistor Q4 is an NPN transistor. The collector of the fourth transistor Q4 is electrically connected to the power supply VCC, the emitter is connected to the voltage output Vout, and the base is electrically connected to the output terminal of the voltage reference source. The first end of the sixth resistor R6 is electrically connected to the emitter of the fourth transistor Q4, and the second end is grounded.

[0035] The above description merely illustrates preferred embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A radiation-resistant pre-regulatory circuit with a wide power supply voltage range, characterized in that, include: Bias circuit, voltage reference source and output buffer circuit, among which, The bias circuit includes a first current mirror and an emitter junction reference current source. The input terminal of the first current mirror is electrically connected to the power supply VCC, and its output terminal is connected to the input terminal of the voltage reference source to output a stable bias current. The bias feedback loop is used to generate a reference current. The voltage reference source includes a temperature compensation circuit and a bandgap core circuit. The input terminal of the temperature compensation circuit is electrically connected to the output terminal of the first current mirror as the input terminal of the voltage reference source, and is used to generate a temperature compensation voltage. The input terminal of the bandgap core circuit is electrically connected to the output terminal of the temperature compensation circuit, and is used to generate a reference voltage. An output buffer circuit is provided, with its input terminal connected to the reference voltage, for buffering and driving the reference voltage.

2. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 1, characterized in that, The first current mirror includes a first transistor Q1 and a second transistor Q2. Both the first transistor Q1 and the second transistor Q2 are PNP transistors. The base of the first transistor Q1 is electrically connected to the base of the second transistor Q2. The emitters of both the first transistor Q1 and the second transistor Q2 are electrically connected to the power supply VCC. The base and collector of the first transistor Q1 are short-circuited.

3. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 2, characterized in that, The emitter junction reference current source includes a first resistor R1, a second resistor R2, a twelfth transistor Q12, and a thirteenth transistor Q13, wherein the twelfth transistor Q12 and the thirteenth transistor Q13 are both NPN transistors; the first end of the first resistor R1 is electrically connected to the emitter of the first transistor Q1, and the second end is electrically connected to the base of the twelfth transistor Q12 and the collector of the thirteenth transistor Q13; the first end of the second resistor R2 is electrically connected to the emitter of the twelfth transistor Q12 and the base of the thirteenth transistor Q13, and the second end is electrically connected to the emitter of the thirteenth transistor Q13 and grounded; the collector of the twelfth transistor Q12 is electrically connected to the base of the first transistor Q1.

4. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 1, characterized in that, The temperature compensation circuit includes several NPN transistors whose emitters and collectors are connected in sequence, and whose bases and collectors are short-circuited.

5. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 1, characterized in that, The temperature compensation circuit includes a third transistor Q3, a fifth transistor Q5, a sixth transistor Q6, a seventh transistor Q7, and an eighth transistor Q8. The bases of all transistors Q3, Q5, Q6, Q7, and Q8 are shorted to their collectors. The collector of the third transistor Q3 is connected to the bias current of the first current mirror, and its emitter is electrically connected to the collector of the fifth transistor Q5. The emitter of the fifth transistor Q5 is electrically connected to the collector of the sixth transistor Q6. The emitter of the sixth transistor Q6 is electrically connected to the collector of the seventh transistor Q7. The emitter of the seventh transistor Q7 is electrically connected to the collector of the eighth transistor Q8. The emitter of the eighth transistor Q8 outputs the reference voltage.

6. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 5, characterized in that, The bandgap core circuit includes a ninth transistor Q9, a thirteenth transistor Q10, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. Both the ninth and thirteenth transistors Q9 and Q10 are NPN transistors, with their bases electrically connected to form a second current mirror. The base and collector of the ninth transistor Q9 are short-circuited, and its emitter is grounded. The first terminal of the third resistor R3 is electrically connected to the emitter of an eighth transistor Q8, and its second terminal is electrically connected to the collector of the ninth transistor Q9. The first terminal of the fourth resistor R4 is electrically connected to the emitter of the eighth transistor Q8, and its second terminal is electrically connected to the collector of the thirteenth transistor Q10. The first terminal of the fifth resistor R5 is electrically connected to the emitter of the thirteenth transistor Q10, and its second terminal is grounded.

7. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 6, characterized in that, The emitter area ratio of the ninth transistor Q9 and the thirteenth transistor Q10 is 1:4; the resistance values ​​of the third resistor R3 and the fourth resistor R4 are equal.

8. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 7, characterized in that, The emitter area ratio of the fifth transistor Q5, the sixth transistor Q6, the seventh transistor Q7, and the eighth transistor Q8 to that of the ninth transistor Q9 is 2:

1.

9. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 6, characterized in that, The voltage reference source also includes an eleventh transistor Q11 as a reference voltage output interface; the base of the eleventh transistor Q11 is electrically connected to the second terminal of the fourth resistor R4 and the collector of the thirteenth transistor Q10; the emitter of the eleventh transistor Q11 is grounded; and the collector of the eleventh transistor Q11 is electrically connected to the base of the third transistor Q3.

10. The wide power supply voltage range radiation-resistant pre-regulatory circuit as described in claim 1, characterized in that, The output buffer circuit includes a fourth transistor Q4 and a sixth resistor R6. The fourth transistor Q4 is an NPN transistor. The collector of the fourth transistor Q4 is electrically connected to the power supply VCC, the emitter is connected to the voltage output Vout, and the base is electrically connected to the output terminal of the voltage reference source. The first end of the sixth resistor R6 is electrically connected to the emitter of the fourth transistor Q4, and the second end is grounded.

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