Band-gap reference circuit

Abstract

The invention discloses a band-gap reference circuit, which belongs to the technical field of integrated circuits and comprises a reference core unit, an error amplification unit and an output unit which are connected in sequence. According to the band-gap reference circuit, the reference voltage VREF can be finely adjusted through the base current, and limitation of technological parameters on the reference voltage VREF is avoided; the fixed voltage source used by the operational amplifier in the circuit can reduce the influence of the cathode voltage on the reference voltage VREF and improve the stability of the reference voltage; the compensation current unit in the circuit can counteract the base current, so that the reference voltage VREF is reduced, and the temperature curve at the high-temperature position is finely adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a bandgap reference circuit. Background Art

[0002] Bandgap reference circuits are key modules in modern analog and mixed-signal integrated circuits, and their performance directly impacts the accuracy and stability of the entire system. With the continuous expansion of application scenarios and the increasing performance requirements for analog chips, more stringent requirements are being placed on the accuracy, stability, and power supply rejection capabilities of reference voltage circuits.

[0003] Figure 1 For traditional 2.5V bandgap reference circuit, such as Figure 1 The bandgap reference circuit shown includes a reference core unit 11, an error amplifying unit 12, and an output unit 13, which are connected in sequence. The reference core unit 11 includes multiple transistors and multiple resistors. The second end of the transistor Q4 is connected to the cathode voltage V - The first end of transistor Q4 is connected to the first end of resistor R4, and the third end of transistor Q4 outputs the reference voltage V REF The second end of the resistor R4 is connected to the first end of the resistor R3 and the first end of the resistor R1, the second end of the resistor R3 is connected to the second end of the transistor Q2, and the first end of the transistor Q2 is connected to the first end of the resistor R2; the second end of the resistor R1 is connected to the second end and the third end of the transistor Q1 and the third end of the transistor Q2, and the first end of the transistor Q1 is connected to the second end of the resistor R2 and the anode voltage V + The error amplifier unit 12 includes a plurality of transistors, and the first end of the transistor Q5 is connected to the cathode voltage V - The second end of the transistor Q3 is connected to the second end and the third end of the transistor Q5 and the third end of the transistor Q6. The second end of the transistor Q6 is connected to the second end of the transistor Q7. The third end of the transistor Q7 is connected to the third end of the transistor Q1. The third end of the transistor Q3 is connected to the second end of the transistor Q2. The first end of the transistor Q3 is connected to the first end of the transistor Q7 and the anode voltage V + The output unit 13 includes a plurality of transistors and a plurality of resistors. The second end of the transistor Q10 is connected to the cathode voltage V - and the second end of the transistor Q11, the third end of the transistor Q10 is connected to the second end of the transistor Q6, the first end of the transistor Q10 is connected to the first end of the resistor R12, the second end of the resistor R12 is connected to the first end of the resistor R13 and the third end of the transistor Q11, and the second end of the resistor R13 is connected to the first end of the transistor Q11 and the anode voltage V + .

[0004] The operational amplifier composed of transistors Q3, Q7, Q5 and Q6 controls the base potential of transistor Q3 to be equal to that of transistor Q1, that is, V BE1 =V BE3 , so the voltage drops across resistors R1 and R3 are equal. Suppose the collector current of transistor Q1 is I C1 , the collector current of Q2 is I C2 .

[0005] So we have: (1) in, is the voltage drop across resistor R3, Has a positive temperature coefficient, k is the Boltzmann constant ( ), q is the electron charge ( ), T is the absolute temperature (K), V T is the thermoelectric potential, m It is a parameter related to the process.

[0006] Get the reference voltage: (2) in, Has a negative temperature coefficient, Has a positive temperature coefficient, k is the Boltzmann constant ( ), q is the electron charge ( ), T is the absolute temperature (K), V T is the thermoelectric potential, m It is a parameter related to the process.

[0007] However, the current conventional reference voltage generation circuit has two significant defects in practical applications: First, the generated reference voltage is susceptible to fluctuations in the semiconductor manufacturing process. Because process parameters are difficult to maintain completely consistent throughout the production process, the final output reference voltage can deviate from the preset 2.5V target value. This makes it impossible to ensure the accuracy and consistency of the reference voltage, which in turn adversely affects the performance of circuit modules that rely on it. Secondly, the operating voltage of the second-stage operational amplifier in conventional circuits is derived from the cathode voltage of the main chip. When the cathode voltage of the chip fluctuates due to external power supply fluctuations, load changes, or other operating factors, it directly affects the operating point and output characteristics of the op amp, causing deviations in the output signal. This deviation is further transmitted to the reference voltage, causing instability and ultimately reducing the output accuracy of the entire chip. Summary of the Invention

[0008] The present invention utilizes the base current of a transistor to design a small-term voltage compensation circuit, which can compensate for the difference in reference output voltage caused by differences in transistor device parameters under different processes. The output voltage is fine-tuned and raised based on the bandgap reference voltage determined by the process to obtain an accurate 2.5V reference voltage. At the same time, the temperature coefficient of the base current can participate in compensating the temperature curve of the reference voltage, thereby reducing the temperature drift of the reference.

[0009] To achieve the above object, the technical solution of the present invention is: A bandgap reference circuit includes a reference core unit, an error amplification unit, and an output unit, which are connected in sequence. The reference core unit includes multiple triodes, multiple resistors, multiple transistors, and a diode. The second end of the fourth triode is connected to a cathode voltage, the first end of the fourth triode is connected to the first end of the fourth resistor, the second end of the fourth resistor is connected to the first end of the third resistor and the first end of the first resistor, the second end of the third resistor is connected to the second end of the second triode and the third end of the eighth triode, and the first end of the second triode is connected to the first end of the second resistor. The second end of the first resistor is connected to the second end and the third end of the first triode and the third end of the second triode, and the first end of the first triode is connected to the second end of the second resistor, the second end of the ninth resistor, and the anode voltage. The first end of the fifth resistor is connected to the cathode voltage and the first end of the sixth resistor, the second end of the fifth resistor is connected to the first end of the first transistor, the second end of the eighth triode is connected to the second end and the third end of the first transistor, and the third end of the second transistor, the first end of the eighth triode is connected to the first end of the ninth resistor, the second end of the sixth resistor is connected to the first end of the second transistor, the second end of the second transistor is connected to the cathode of the first diode, and the anode of the first diode is grounded.

[0010] In a specific embodiment, the error amplification unit includes multiple transistors, multiple resistors and a capacitor; the first end of the fifth transistor is connected to the second end of the second transistor and the first end of the sixth transistor, the second end of the third transistor is connected to the second end and the third end of the fifth transistor and the third end of the sixth transistor, the third end of the third transistor is connected to the third end of the eighth transistor, the first end of the third transistor is connected to the first end of the zeroth resistor and the first end of the seventh transistor, the second end of the sixth transistor is connected to the first end of the first capacitor and the second end of the seventh transistor, the second end of the first capacitor is connected to the first end of the eleventh resistor, the second end of the eleventh resistor is connected to the third end of the second transistor and the third end of the seventh transistor, and the second end of the zeroth resistor is connected to the anode voltage.

[0011] Furthermore, the output unit includes a third transistor and a second capacitor; the second end of the third transistor is connected to the cathode voltage, the third end of the third transistor is connected to the second end of the seventh transistor and the first end of the second capacitor, and the second end of the second capacitor is connected to the first end of the third transistor and the anode voltage.

[0012] In a specific embodiment, the bandgap reference circuit also includes a compensation current unit; the compensation current unit includes multiple resistors, multiple transistors and a ninth transistor; the first end of the seventh resistor is connected to the first end of the fifth transistor and the second end of the second transistor, the second end of the seventh resistor is connected to the first end of the eighth resistor and the first end of the fourth transistor, the second end of the ninth transistor is connected to the second end and the third end of the fifth transistor, the second end of the eighth resistor and the third end of the fourth transistor, the first end of the ninth transistor is connected to the first end of the tenth resistor, the third end of the ninth transistor is connected to the third end of the third transistor, and the second end of the tenth resistor is connected to the anode voltage.

[0013] Furthermore, the reference voltage V REF The expression is: in, V BE1 is the base-emitter voltage of the first transistor, V BE4 is the base-emitter voltage of the fourth transistor, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, and R4 is the resistance of the fourth resistor. is the change in the base-emitter voltage of the transistor, k 2 I B1 is the current drawn from the base of the third transistor and the eighth transistor to the collector of the second transistor, I C2is the collector current of the second transistor, β is the transistor amplification factor, Vos is the input offset voltage of the error amplifier.

[0014] Furthermore, the reference voltage V REF The temperature coefficient includes V BE1 +V BE4 、 and the temperature coefficient of the small term; where, V BE1 +V BE4 is a positive temperature coefficient, is a negative temperature coefficient, is the small term temperature coefficient.

[0015] Furthermore, by adjusting the size of the zeroth resistor, the ninth resistor, and the tenth resistor, the base-emitter voltage difference of the third transistor, the seventh transistor, the eighth transistor, and the ninth transistor is adjusted, thereby adjusting the size of the small-term compensation voltage. By adjusting the size of the fourth resistor, the The positive temperature coefficient of the term.

[0016] Furthermore, the resistance of the first resistor is equal to that of the third resistor.

[0017] Furthermore, the third transistor, the seventh transistor, the fifth transistor, the sixth transistor and the zeroth resistor constitute an error amplifier.

[0018] Furthermore, the first diode is a Zener diode.

[0019] Beneficial effect: a bandgap reference circuit of the present invention can use the base current to adjust the reference voltage V REF Fine-tune to avoid process parameters affecting the reference voltage V REF The fixed voltage source used by the operational amplifier in this circuit can reduce the cathode voltage to the reference voltage. V REF The compensation current unit in this circuit can offset the base current, thereby reducing the reference voltage V REF , and fine-tune the temperature curve at its high temperature.

[0020] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a traditional 2.5V bandgap reference circuit.

[0022] Figure 2 The figure is a schematic structural diagram of a bandgap reference circuit of the present invention.

[0023] Figure 3 This is a circuit diagram of a first specific embodiment of a bandgap reference circuit according to the present invention.

[0024] Figure 4 This is a circuit diagram of a second specific embodiment of a bandgap reference circuit of the present invention.

[0025] Figure 5 for Figure 3 The temperature curve of the transistor base current in the first specific embodiment is shown.

[0026] Figure 6 This is the simulation waveform of the traditional 2.5V bandgap reference circuit.

[0027] Figure 7 for Figure 3 The simulation waveform diagram of the first specific embodiment is shown.

[0028] Figure 8 for Figure 4 The simulation waveform diagram of the second specific embodiment is shown.

[0029] Figure 9 Reference voltage at different temperatures V REF Schematic diagram of the change with cathode voltage.

[0030] In the drawings, like reference numerals refer to the same drawing elements. DETAILED DESCRIPTION

[0031] To make the purpose and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Figure 2 FIG. 1 is a schematic diagram of the structure of a bandgap reference circuit of the present invention. Figure 2 As shown, a bandgap reference circuit includes a reference core unit 21, an error amplifying unit 22, and an output unit 23, which are connected in sequence.

[0033] More specifically, the reference core unit 21 provides a voltage source for the error amplifier unit 22, and generates a reference voltage together with the error amplifier unit 22. V REF , the output unit 23 is used to ensure the load capacity of the circuit.

[0034] Figure 3 FIG. 1 is a circuit diagram of a first specific embodiment of a bandgap reference circuit according to the present invention. Figure 3 As shown, a bandgap reference circuit includes a reference core unit 31, an error amplifying unit 32, and an output unit 33, which are connected in sequence.

[0035] Furthermore, the reference core unit 31 includes a plurality of transistors, a plurality of resistors, a plurality of transistors and a diode. The second end of the transistor Q4 is connected to the cathode voltage V - The first end of transistor Q4 is connected to the first end of resistor R4, and the third end of transistor Q4 outputs the reference voltage V REF The second end of the resistor R4 is connected to the first end of the resistor R3 and the first end of the resistor R1, the second end of the resistor R3 is connected to the second end of the transistor Q2 and the third end of the transistor Q8, the first end of the transistor Q2 is connected to the first end of the resistor R2 and the node DVBE; the second end of the resistor R1 is connected to the second end and the third end of the transistor Q1 and the third end of the transistor Q2, the first end of the transistor Q1 is connected to the second end of the resistor R2, the second end of the resistor R9 and the anode voltage V + ; The first end of the resistor R5 is connected to the cathode voltage V - and a first end of the resistor R6, a second end of the resistor R5 is connected to the first end of the transistor M1, a second end of the transistor Q8 is connected to the second end and the third end of the transistor M1 and the third end of the transistor M2, a first end of the transistor Q8 is connected to the first end of the resistor R9; the second end of the resistor R6 is connected to the first end of the transistor M2, the second end of the transistor M2 is connected to the cathode of the diode D1, and the anode of the diode D1 is grounded.

[0036] Furthermore, the error amplification unit 32 includes multiple transistors, multiple resistors, and a capacitor. The first end of the transistor Q5 is connected to the second end of the transistor M2, the first end of the transistor Q6, and the power supply VDDL. The second end of the transistor Q3 is connected to the second end and the third end of the transistor Q5 and the third end of the transistor Q6. The third end of the transistor Q3 is connected to the third end of the transistor Q8. The first end of the transistor Q3 is connected to the first end of the resistor R0 and the first end of the transistor Q7. The second end of the transistor Q6 is connected to the first end of the capacitor C1 and the second end of the transistor Q7. The second end of the capacitor C1 is connected to the first end of the resistor R11. The second end of the resistor R11 is connected to the third end of the transistor Q2 and the third end of the transistor Q7. The second end of the resistor R0 is connected to the anode voltage V + .

[0037] Furthermore, the output unit 33 includes a transistor M3 and a capacitor C2, and the second end of the transistor M3 is connected to the cathode voltage V - The third end of the transistor M3 is connected to the second end of the transistor Q7 and the first end of the capacitor C2, and the second end of the capacitor C2 is connected to the first end of the transistor M3 and the anode voltage V + .

[0038] Optionally, the transistor M1 , the transistor M2 and the transistor M3 may be MOSFETs; the first terminal of each transistor is its source, the second terminal of each transistor is its drain, and the third terminal of each transistor is its gate.

[0039] More specifically, the transistors M1 and M2 are P-type MOSFETs, and the transistor M3 is an N-type MOSFET.

[0040] Optionally, transistors Q1 to Q4, Q7, and Q8 are NPN transistors, and transistors Q5 and Q6 are PNP transistors. The first end of each transistor is its emitter, the second end of each transistor is its collector, and the third end of each transistor is its base.

[0041] Optionally, the diode D1 is a Zener diode.

[0042] Next, continue to combine Figure 3 The working principle of a bandgap reference circuit of the present invention is introduced. In the reference core unit 31, transistors M1, M2, resistors R5, and R6 form a current mirror and flow through diode D1 to generate an internal small voltage source VDDL, which is used as the power supply of the error amplifier unit 32 to reduce the cathode voltage to the reference voltage. V REF and improve the reference voltage stability.

[0043] The error amplifier unit 32, transistors Q3, Q7, Q5, Q6 and resistor R0 form an error amplifier for clamping the collector voltages of transistors Q1 and Q2. Vos is the input offset voltage of the error amplifier. The resistor R11 and capacitor C1 connected between the base and collector of transistor Q7 are a compensation network used to adjust the loop stability of the system. Among them, the size of resistor R0 affects the base-emitter voltage difference of the three transistors, transistor Q8, transistor Q3, and transistor Q7, thereby affecting their bias current. Transistor Q7 and transistor Q1 are a pair of current mirrors. It can be approximately considered that transistor Q8 and transistor Q3 also form a current mirror with transistor Q1. Due to the limited amplification factor of the transistor, the base of transistor Q7, transistor Q3, and transistor Q8 respectively draw current from the collector of transistor Q1 and transistor Q2, and their sizes are recorded as k 1 I B1 and k 2 I B1 ,in k 1 and k 2 Affected by the area ratio of the transistors and the size of resistors R0 and R9: The larger the area of ​​transistors Q3 and Q7 relative to transistor Q1, k 1 and k 2 The larger the resistance R0 and the resistance R9, k 1 and k 2 The smaller.

[0044] Furthermore, the transistor M3 in the output unit 33 is a large-size power transistor, which is used to ensure the load capacity of the circuit.

[0045] More specifically, let the collector current of transistor Q1 be I C1 , the collector current of Q2 is I C2 The currents on resistors R1 and R3 are: (3) (4) Taking into account the offset of the error amplifier, the voltage drops across resistors R1 and R3 have the following relationship: (5) Right now: (6) Thus, the ratio of the collector current of transistor Q1 and transistor Q2 is obtained: (7) The voltage drop across resistor R2 is then: (8) in, Has a positive temperature coefficient, k is the Boltzmann constant ( ), q is the electron charge ( ), T is the absolute temperature (K), V T is the thermoelectric potential; I S1 and I S2 are the reverse saturation currents of transistor Q1 and transistor Q2 respectively, and the number of transistors Q1 and Q2 in parallel is 1:m ,so , m It is a parameter related to the process.

[0046] Will k 2 I B1 Taking into account the base current of transistor Q2, the current flowing through resistor R3 is as follows: (9) in, β is the transistor amplification factor.

[0047] Thus, the reference voltage expression is obtained: (10) When the resistors R1 and R3 satisfy: R1=R3, we have: (11) in, V BE1 is the base-emitter voltage of the first transistor, V BE4 is the base-emitter voltage of the fourth transistor, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, and R4 is the resistance of the fourth resistor. is the change in the base-emitter voltage of the transistor.

[0048] in, This is an additional small term that can increase the reference voltageV REF , and its own temperature coefficient can affect the reference voltage V REF The temperature coefficient is compensated. The simulation results show that the current I B1 Changes with temperature Figure 5 As shown in the figure, from -55℃ to 125℃, its temperature coefficient first shows a negative temperature and then a positive temperature. V REF In the reference voltage V REF The temperature coefficient includes V BE1 +V BE4 Positive temperature coefficient, The negative temperature coefficient and temperature coefficient of the small term, the introduction of the small term voltage makes the reference voltage V REF Based on the traditional reference circuit voltage formula (2), the base-emitter voltage difference of transistors Q3, Q7, and Q8 can be adjusted by adjusting the size of resistors R0 and R9, thereby fine-tuning the size of the small-term compensation voltage. By adjusting the size of resistor R4, the The positive temperature coefficient of the term, the two parts of the resistance work together, and finally the reference voltage V REF Accurately achieve 2.5V while minimizing temperature drift.

[0049] Figure 6 This is the simulation waveform of the traditional 2.5V reference circuit. Under the current process, the reference voltage at the point where the slope of the temperature curve is 0 V REF The output voltage is only 2.436V, and it changes by 11.6mV in the full temperature range of -55℃ to 125℃, with a temperature drift of 25.78ppm / ℃. V REF Different processes will have varying degrees of fluctuation, and in most cases it is impossible to obtain exactly 2.5V. Using this solution, by properly adjusting resistors R0, R9, and R4, a precise 2.5V output voltage can be obtained. Figure 7 for Figure 3 The simulation waveform diagram of the first specific embodiment is shown in FIG. Figure 7 As shown, under the compensation of the small voltage temperature coefficient, the reference voltage V REF The temperature drift is reduced to 4.56ppm / °C over the full temperature range.

[0050] In summary, this circuit can use the base current to adjust the reference voltage VREF Fine-tune to avoid process parameters affecting the reference voltage V REF The fixed voltage source used by the operational amplifier in this circuit can reduce the cathode voltage to the reference voltage. V REF and improve the reference voltage stability.

[0051] Figure 4 FIG. 1 is a circuit diagram of a second specific embodiment of a bandgap reference circuit according to the present invention. Figure 4 As shown, a bandgap reference circuit includes a reference core unit 41 , an error amplifying unit 42 , an output unit 43 , and a compensation current unit 44 . The reference core unit 41 , the error amplifying unit 42 , and the output unit 43 are connected in sequence, and the compensation current unit 44 is connected to the reference core unit 41 .

[0052] Figure 4 Specific embodiments and Figure 3 The difference between the specific embodiment of the present invention and the present invention is that the present invention further includes a compensation current unit 44. The compensation current unit 44 includes multiple resistors, multiple transistors, and a transistor Q9. The first end of the resistor R7 is connected to the first end of the transistor M5 and the voltage source VDDL, the second end of the resistor R7 is connected to the first end of the resistor R8 and the first end of the transistor M4, the second end of the transistor Q9 is connected to the second end and the third end of the transistor M5, the second end of the resistor R8, and the third end of the transistor M4, the second end of the transistor M4 is connected to the node DVBE, the first end of the transistor Q9 is connected to the first end of the resistor R10, the third end of the transistor Q9 is connected to the third end of the transistor Q3, and the second end of the resistor R10 is connected to the anode voltage V + The node DVBE is the first end of the resistor R2.

[0053] Optionally, the transistor M4 and the transistor M5 may be MOSFETs; the first terminal of each transistor is its source, the second terminal of each transistor is its drain, and the third terminal of each transistor is its gate.

[0054] More specifically, the transistor M4 and the transistor M5 are P-type MOSFETs.

[0055] Optionally, the transistor Q9 is an NPN transistor, wherein the first end of the transistor is its emitter, the second end of the transistor is its collector, and the third end of the transistor is its base.

[0056] In this embodiment, k 1 and k 2 Affected by the area ratio of the transistors and the size of resistors R0, R9 and R10: The larger the area of ​​transistors Q3 and Q7 relative to transistor Q1,k 1 and k 2 The larger the resistance R0, resistance R9, and resistance R10, k 1 and k 2 By adjusting the size of resistor R0, resistor R9, and resistor R10, the base-emitter voltage difference of transistor Q3, transistor Q7, transistor Q8, and transistor Q9 can be adjusted, thereby fine-tuning the size of the small-term compensation voltage. By adjusting the size of resistor R4, the The positive temperature coefficient of the term, the two parts of the resistance work together, and finally the reference voltage V REF Accurately achieve 2.5V while minimizing temperature drift.

[0057] for Figure 3 For the specific embodiment in the embodiment, if the temperature coefficient model is inaccurate or the high temperature junction leakage of the core transistor is too large, the measured reference voltage V REF At high temperatures, the compensation current unit 44 can adjust the reference voltage at high temperatures without adjusting the ratio of other resistors in the bandgap reference circuit. V REF Make adjustments, and here's how it works.

[0058] The collector current of transistor Q9 can be regarded as the reference core unit 41 current like transistor Q8 and transistor Q3. I C2 The mirror current is recorded as ( k 9 Represents the current mirror ratio, whose size is determined by the resistance value of resistor R10 and the area ratio of transistor Q9 to transistor Q1). The current flows through transistor M4 and resistors R7 and R8. When the current is small enough and the voltage drop on resistor R8 is small enough, transistor M4 cannot be turned on, and the current flows entirely through resistors R7 and R8. At this time, the gate-source voltage of transistor M4 is V GS4 is the voltage drop across resistors R7 and R8 From formula (1), we can see that I C2 The size is proportional to the temperature. When the temperature rises to a certain level, the gate-source voltage of transistor M4 V GS4 Increases to the threshold voltage of transistor M4, transistor M4 is turned on, the temperature rises further, and the gate-source voltage of transistor M4 V GS4 Further increase, , transistor M3 is turned on, and its channel current is injected into node DVBE, which is equivalent to partially offsetting the current drawn from the collector node of transistor Q1 and transistor Q2. k 1 I B1 and k 2 I B1 , thus the reference voltage V REF Pull down.

[0059] From the above circuit analysis process, it can be seen that the size of resistors R7 and R8 can control the temperature node at which transistor M4 turns on. Furthermore, the resistance ratio of resistors R7 and R8 can control the temperature node at which transistor M3 turns on, thereby controlling the reference voltage. V REF The temperature node starts to be pulled down; transistor M3 and transistor M4 form a current mirror structure. The current of transistor M3 is determined by the ratio of the sizes of the two and the ratio of the resistance values ​​of resistors R7 and R8. Adjusting the above two ratios can control the current injected by transistor M3 into node DVBE, thereby controlling the reference voltage. V REF Therefore, the compensation current unit 44 can flexibly adjust the reference voltage at high temperature. V REF And set the temperature node for adjusting the reference voltage. Figure 8 for Figure 4 The simulation waveform diagram of the second specific embodiment is shown in FIG. Figure 8 As shown in the figure, the reference voltage of the reference circuit is given when the resistance value of resistor R8 is different. V REF In the simulation waveform, the blue line shows the minimum value of resistor R8. Transistor M3 is always closed in the full temperature range, so the current compensation stage does not work and the reference voltage V REF Will not be pulled down; the green line is the resistor R8 takes a larger value, the transistor M3 starts to open at about 40℃, and its current is injected into the node DVBE, the reference voltage V REF The simulation results show that the design of the current compensation stage can compensate for the extracted base current at high temperature, thereby reducing the reference voltage V REF In practice, by adjusting the resistance of resistor R8, the effect of the current compensation stage can be adjusted to be between the green and blue lines.

[0060] Figure 9 Reference voltage at different temperatures V REF Schematic diagram of the change of cathode voltage. At room temperature, the cathode voltage changes from V REF In the process of increasing to 36V, the reference voltage V REF The change is about 10mV.

[0061] In summary, this circuit can use the base current to adjust the reference voltage V REF Fine-tune to avoid process parameters affecting the reference voltage V REF The fixed voltage source used by the operational amplifier in this circuit can reduce the cathode voltage to the reference voltage. V REF The compensation current unit in this circuit can offset the base current, thereby reducing the reference voltage V REF , and fine-tune the temperature curve at its high temperature.

[0062] Although the present invention has been disclosed above with reference to the embodiments, they are not intended to limit the present invention. Anyone with ordinary skill in the art may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent applications.

Claims

1. A bandgap reference circuit, characterized in that: The invention comprises a reference core unit, an error amplifying unit, and an output unit, which are connected in sequence; the reference core unit comprises a plurality of triodes, a plurality of resistors, a plurality of transistors, and a diode; the second end of the fourth triode is connected to a cathode voltage, the first end of the fourth triode is connected to a first end of a fourth resistor, the second end of the fourth resistor is connected to a first end of a third resistor and a first end of the first resistor, the second end of the third resistor is connected to a second end of the second triode and a third end of an eighth triode, and the first end of the second triode is connected to the first end of the second resistor; the second end of the first resistor is connected to the second end and the third end of the first triode and the third end of the second triode, the first end of the first triode is connected to the second end of the second resistor, the second end of the ninth resistor, and an anode voltage; the first end of the fifth resistor is connected to a cathode voltage and the first end of the sixth resistor, the second end of the fifth resistor is connected to the first end of the first transistor, the second end of the eighth triode is connected to the second end and the third end of the first transistor, and the third end of the second transistor, the first end of the eighth triode is connected to the first end of the ninth resistor, the second end of the sixth resistor is connected to the first end of the second transistor, the second end of the second transistor is connected to the cathode of the first diode, and the anode of the first diode is grounded.

2. A bandgap reference circuit as claimed in claim 1, characterized in that: The error amplification unit includes multiple transistors, multiple resistors and a capacitor; the first end of the fifth transistor is connected to the second end of the second transistor and the first end of the sixth transistor, the second end of the third transistor is connected to the second end and the third end of the fifth transistor and the third end of the sixth transistor, the third end of the third transistor is connected to the third end of the eighth transistor, the first end of the third transistor is connected to the first end of the zeroth resistor and the first end of the seventh transistor, the second end of the sixth transistor is connected to the first end of the first capacitor and the second end of the seventh transistor, the second end of the first capacitor is connected to the first end of the eleventh resistor, the second end of the eleventh resistor is connected to the third end of the second transistor and the third end of the seventh transistor, and the second end of the zeroth resistor is connected to the anode voltage.

3. A bandgap reference circuit as claimed in claim 2, characterized in that: The output unit includes a third transistor and a second capacitor; the second end of the third transistor is connected to the cathode voltage, the third end of the third transistor is connected to the second end of the seventh transistor and the first end of the second capacitor, and the second end of the second capacitor is connected to the first end of the third transistor and the anode voltage.

4. A bandgap reference circuit as claimed in claim 3, characterized in that: The bandgap reference circuit also includes a compensation current unit; the compensation current unit includes multiple resistors, multiple transistors and a ninth transistor; the first end of the seventh resistor is connected to the first end of the fifth transistor and the second end of the second transistor, the second end of the seventh resistor is connected to the first end of the eighth resistor and the first end of the fourth transistor, the second end of the ninth transistor is connected to the second end and the third end of the fifth transistor, the second end of the eighth resistor and the third end of the fourth transistor, the first end of the ninth transistor is connected to the first end of the tenth resistor, the third end of the ninth transistor is connected to the third end of the third transistor, and the second end of the tenth resistor is connected to the anode voltage.

5. A bandgap reference circuit as claimed in claim 4, characterized in that: Reference voltage V REF The expression is: in, V BE1 is the base-emitter voltage of the first transistor, V BE4 is the base-emitter voltage of the fourth transistor, R1 is the resistance of the first resistor, R2 is the resistance of the second resistor, R3 is the resistance of the third resistor, and R4 is the resistance of the fourth resistor. is the change in the base-emitter voltage of the transistor, k 2 I B1 is the current drawn from the base of the third transistor and the eighth transistor to the collector of the second transistor, I C2 is the collector current of the second transistor, β is the transistor amplification factor, Vos is the input offset voltage of the error amplifier.

6. A bandgap reference circuit as claimed in claim 5, characterized in that: The reference voltage V REF The temperature coefficient includes V BE1 +V BE4 、 and the temperature coefficient of the small term; where, V BE1 +V BE4 is a positive temperature coefficient, is a negative temperature coefficient, is the small term temperature coefficient.

7. A bandgap reference circuit as claimed in claim 6, characterized in that: By adjusting the size of the zeroth resistor, the ninth resistor, and the tenth resistor, the base-emitter voltage difference of the third transistor, the seventh transistor, the eighth transistor, and the ninth transistor is adjusted, thereby adjusting the size of the small-term compensation voltage. By adjusting the size of the fourth resistor, the The positive temperature coefficient of the term.

8. A bandgap reference circuit as claimed in claim 7, characterized in that: The resistance values ​​of the first resistor and the third resistor are equal.

9. A bandgap reference circuit as claimed in claim 8, characterized in that: The third transistor, the seventh transistor, the fifth transistor, the sixth transistor and the zeroth resistor form an error amplifier.

10. The bandgap reference circuit according to claim 9, wherein: The first diode is a Zener diode.

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