Band-gap reference circuit and chip

Abstract

The invention discloses a band-gap reference circuit and a chip. The band-gap reference circuit comprises a band-gap reference core module, a first trimming module and a second trimming module, the band-gap reference core module is used for generating reference voltage; the output end of the first trimming module is connected with a first adjusting point of the band-gap reference core module, and the first trimming module is used for outputting a first trimming signal; a first output end of the second trimming module is connected with a second adjusting point of the band-gap reference core module, a second output end of the second trimming module is connected with a third adjusting point of the band-gap reference core module, and the second trimming module is used for outputting a second trimming signal; and the band-gap reference core module is also used for adjusting the reference voltage according to the first trimming signal and the second trimming signal. The band-gap reference circuit provided by the invention is relatively high in trimming speed.

Description

Technical Field

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

[0002] The bandgap reference circuit provides a DC reference voltage that is basically independent of the process, power supply voltage, and temperature. It has the advantages of low power consumption and good long-term stability, and is widely used in data conversion systems, power management chips, and various test instruments. Due to factors such as process parameter changes and device matching, the output voltage may be greatly offset. The trimming technology can perform personalized calibration on each chip, thereby improving the yield and performance consistency of the entire batch of products.

[0003] At present, the bandgap reference circuit is generally adjusted by single resistor adjustment or adaptive adjustment to adjust the circuit characteristics to make it closer to the target. The above adjustment steps are relatively complicated and the adjustment process is time-consuming. Summary of the invention

[0004] The present invention provides a bandgap reference circuit and a chip to solve the problem of a long time-consuming trimming process in the prior art.

[0005] According to one aspect of the present invention, there is provided a bandgap reference circuit, comprising a bandgap reference core module, a first trimming module and a second trimming module;

[0006] The bandgap reference core module is used to generate a reference voltage;

[0007] The output end of the first trimming module is connected to the first adjustment point of the bandgap reference core module, and the first trimming module is used to output a first trimming signal;

[0008] The first output end of the second trimming module is connected to the second adjustment point of the bandgap reference core module, the second output end of the second trimming module is connected to the third adjustment point of the bandgap reference core module, and the second trimming module is used to output a second trimming signal;

[0009] The bandgap reference core module is further configured to adjust the reference voltage according to the first trimming signal and the second trimming signal.

[0010] Optionally, the first adjustment module includes a first switch unit and a second switch unit, the control end of the first switch unit is connected to a first control signal, the first end of the first switch unit is connected to a first power supply end, and the second end of the first switch unit is connected to an output end of the first adjustment module; the control end of the second switch unit is connected to a second control signal, the first end of the second switch unit is connected to the first power supply end, and the second end of the second switch unit is connected to the second power supply end, the first switch unit is used to turn on or off according to the first control signal, and the second switch unit is used to turn on or off according to the second control signal, and the first control signal and the second control signal are inverted signals to each other.

[0011] Optionally, the first switch unit includes at least two first transistors, the control ends of the at least two first transistors are connected to the control end of the first switch unit, the first ends of the at least two first transistors are connected to the first end of the first switch unit, and the second ends of the at least two first transistors are connected to the second end of the first switch unit; the second switch unit includes at least two second transistors, the control ends of the at least two second transistors are connected to the control end of the second switch unit, the first ends of the at least two second transistors are connected to the first end of the second switch unit, and the second ends of the at least two second transistors are connected to the second end of the second switch unit.

[0012] Optionally, the first trimming module also includes a third transistor and a fourth transistor, the control end of the third transistor is connected to the third power supply end, the first end of the third transistor is connected to the first power supply end, the second end of the third transistor is connected to the output end of the first trimming module, the control end of the fourth transistor is grounded, the first end of the fourth transistor is connected to the first power supply end, and the second end of the fourth transistor is connected to the second power supply end.

[0013] Optionally, the second trimming module includes a first mirror unit, a third switch unit and a fourth switch unit, the input end of the first mirror unit is connected to the fourth power supply end, the first mirror unit is used to provide a bias current, the control end of the third switch unit is connected to a third control signal, the first end of the third switch unit is connected to the output end of the first mirror unit, the second end of the third switch unit is connected to the first output end of the second trimming module, the control end of the fourth switch unit is connected to a fourth control signal, the first end of the fourth switch unit is connected to the output end of the first mirror unit, the second end of the fourth switch unit is connected to the second output end of the second trimming module, the third switch unit is used to turn on or off according to the third control signal, the fourth switch unit is used to turn on or off according to the fourth control signal, and the third control signal and the fourth control signal are inverted signals to each other.

[0014] Optionally, the first mirror unit includes a fifth transistor and at least two sixth transistors, the first end of the fifth transistor is connected to the input end of the first mirror unit, the second end of the fifth transistor is grounded, the control ends of the at least two sixth transistors are connected to the control end of the fifth transistor, the first ends of the at least two sixth transistors are connected to the output end of the first mirror unit, and the second ends of the at least two sixth transistors are grounded.

[0015] Optionally, the third switch unit includes at least two seventh transistors, the control ends of the at least two seventh transistors are connected to the control end of the third switch unit, the first ends of the at least two seventh transistors are connected to the first end of the third switch unit, and the second ends of the at least two seventh transistors are connected to the second end of the third switch unit; the fourth switch unit includes at least two eighth transistors, the control ends of the at least two eighth transistors are connected to the control end of the fourth switch unit, the first ends of the at least two eighth transistors are connected to the first end of the fourth switch unit, and the second ends of the at least two eighth transistors are connected to the second end of the fourth switch unit.

[0016] Optionally, the bandgap reference core module includes an operational amplifier unit, a second mirror unit, a ninth transistor and a first resistor, the operational amplifier unit is used to output a positive temperature coefficient voltage, the second mirror unit is connected to the operational amplifier unit, the second mirror unit is used to replicate the positive temperature coefficient voltage, the first end of the first resistor is connected to the output end of the second mirror unit and the output end of the bandgap reference core module, the second end of the first resistor is connected to the first end of the ninth transistor, the second end and the control end of the ninth transistor are grounded, the ninth transistor generates a negative temperature coefficient voltage, and the first resistor generates the reference voltage according to the positive temperature coefficient voltage output by the second mirror unit and the negative temperature coefficient voltage generated by the ninth transistor.

[0017] Optionally, the operational amplifier unit includes a first operational amplifier, a second resistor, a tenth transistor, an eleventh transistor, a twelfth transistor and a thirteenth transistor; the first input end of the first operational amplifier is connected to the first end of the tenth transistor and the second mirror unit, the second input end of the first operational amplifier is connected to the first end of the second resistor and the second mirror unit, the control end of the tenth transistor is connected to the second adjustment point and the first end of the eleventh transistor, the second end of the tenth transistor is connected to the second end of the eleventh transistor, the control end of the eleventh transistor, the second end of the twelfth transistor and the second end of the thirteenth transistor, the control end of the twelfth transistor is connected to the control end of the eleventh transistor, and the first end of the twelfth transistor is connected The third regulating point is connected to the control end of the thirteenth transistor, the first end of the thirteenth transistor is connected to the second end of the second resistor; the second mirror unit includes a fourteenth transistor, a fifteenth transistor and a sixteenth transistor, the first end of the fourteenth transistor is connected to the first input end of the first operational amplifier, the control end of the fourteenth transistor is connected to the control end of the fifteenth transistor, the control end of the sixteenth transistor and the output end of the first operational amplifier, the second end of the fourteenth transistor is connected to the second end of the fifteenth transistor, the second end of the sixteenth transistor and the fifth power supply end, the first end of the fifteenth transistor is connected to the first end of the second resistor, and the first end of the sixteenth transistor is connected to the output end of the second mirror unit.

[0018] According to another aspect of the present invention, a chip is provided, comprising the bandgap reference circuit.

[0019] The technical solution of the embodiment of the present invention provides a bandgap reference circuit, including a bandgap reference core module, a first trimming module and a second trimming module; the bandgap reference core module is used to generate a reference voltage; the output end of the first trimming module is connected to the first adjustment point of the bandgap reference core module, and the first trimming module is used to output a first trimming signal; the first output end of the second trimming module is connected to the second adjustment point of the bandgap reference core module, and the second output end of the second trimming module is connected to the third adjustment point of the bandgap reference core module, and the second trimming module is used to output a second trimming signal; the bandgap reference core module is also used to adjust the reference voltage according to the first trimming signal and the second trimming signal. Among them, the output trimming signals of the first trimming module and the second trimming module are controlled by the signal output by the register. Since the control code can take effect once it is written into the register, the trimming method is simple and convenient, and the trimming speed is fast, which solves the problem of long time-consuming trimming process in the prior art.

[0020] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A bandgap reference circuit diagram is provided in the related art;

[0023] Figure 2 is a schematic structural diagram of a bandgap reference circuit provided by an embodiment of the present invention;

[0024] Figure 3 is a circuit diagram of a first trimming module provided in an embodiment of the present invention;

[0025] Figure 4 is a circuit diagram of a second trimming module provided in an embodiment of the present invention;

[0026] Figure 5 is a circuit diagram of a bandgap reference circuit provided by an embodiment of the present invention;

[0027] Figure 6 is a curve diagram of adjustment results of the first adjustment module provided by an embodiment of the present invention;

[0028] Figure 7 is a curve diagram of adjustment results of the second adjustment module provided in an embodiment of the present invention;

[0029] Figure 8 It is a schematic diagram of the structure of a chip provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The bandgap reference circuit provides a DC reference voltage that is basically independent of the process, power supply voltage, and temperature. It has the advantages of low power consumption and good long-term stability, and is widely used in data conversion systems, power management chips, and various test instruments. The bandgap reference voltage is a superposition of a positive temperature coefficient voltage V1 and a negative temperature coefficient voltage V2. For the voltages V1 and V2 that change in opposite directions with temperature, we select appropriate positive temperature coefficients α1 and negative temperature coefficients α2, so that At this time, the temperature T offset is at a very small level. Thus, a reference voltage V with a temperature coefficient close to zero is obtained. REF =α1V1+α2V2. Figure 1 A bandgap reference circuit diagram is provided in the related art, such as Figure 1 As shown, the bandgap reference circuit is mainly composed of power supply VDD, transistor Q01, transistor Q02, transistor Q03, resistor R01, resistor R02, resistor R03, MOS transistor PM1, MOS transistor PM2, MOS transistor PM3, MOS transistor PM4, MOS transistor PM5, MOS transistor PM6, capacitor C0 and operational amplifier U0. The base emitter Pn junction voltage V BE Negatively correlated with temperature, a positive temperature coefficient voltage is generated by two bipolar transistors operating at different current densities, and the junction voltage difference ΔV BE Related to the positive temperature coefficient. The "virtual short" characteristic of the op amp circuit is used to force the positive and negative input voltages to be equal, so that the voltage difference ΔV generated on R01 BE It is the positive temperature coefficient voltage. The positive temperature coefficient current is mirrored to the right to generate a positive temperature coefficient voltage on R02 and a negative temperature coefficient voltage V of Q03. BE Superposition produces a zero temperature coefficient voltage V BG. Since factors such as process parameter changes and device matching may cause a large deviation in the output voltage, the trimming technology can perform personalized calibration on each chip, thereby improving the yield and performance consistency of the entire batch of products. At present, the trimming method generally adopts single resistor trimming or adaptive adjustment to adjust the circuit characteristics to make it closer to the target. The above trimming steps are relatively complicated, resulting in high time cost.

[0033] In order to solve the above problems, an embodiment of the present invention provides a bandgap reference circuit. Figure 2 is a schematic diagram of a bandgap reference circuit provided by an embodiment of the present invention, such as Figure 2 As shown, the bandgap reference circuit 100 includes a bandgap reference core module 110, a first trimming module 120 and a second trimming module 130; the bandgap reference core module 110 is used to generate a reference voltage Vref; the output terminal a of the first trimming module 120 is connected to the first adjustment point b of the bandgap reference core module, and the first trimming module 120 is used to output a first trimming signal; the first output terminal c of the second trimming module 130 is connected to the second adjustment point d of the bandgap reference core module 110, the second output terminal e of the second trimming module 130 is connected to the third adjustment point f of the bandgap reference core module 110, and the second trimming module 130 is used to output a second trimming signal; the bandgap reference core module 110 is also used to adjust the reference voltage Vref according to the first trimming signal and the second trimming signal.

[0034] In this embodiment, the bandgap reference circuit 100 is a circuit for outputting a reference voltage that is independent of temperature. The bandgap reference core module 110 is a module for outputting a reference voltage, the first trimming module 120 is a module for outputting a first trimming signal, and the second trimming module 130 is a module for outputting a second trimming signal, wherein the first trimming module 120 and the second trimming module 130 are respectively connected to registers, and the first trimming signal and the second trimming signal are controlled by signals output by the registers.

[0035] In this embodiment, the register connected to the first trimming module 120 and the register connected to the second trimming module 130 output a signal of 0 in the default state, and the first trimming module 120 and the second trimming module 130 have no trimming signal output. When the reference voltage increases with the increase of temperature, the second trimming signal output by the second trimming module 130 is controlled by writing a control code in the register, and the bandgap reference core module 110 adjusts the reference voltage according to the second trimming signal. When the reference voltage decreases with the increase of temperature, the first trimming signal output by the first trimming module 120 is controlled by writing a control code in the register, and the bandgap reference core module 110 adjusts the reference voltage according to the first trimming signal. The first trimming module 120 and the second trimming module 130 adjust the positive and negative temperature coefficients of the bandgap reference respectively, without affecting each other.

[0036] The technical solution of this embodiment provides a bandgap reference circuit, including a bandgap reference core module, a first trimming module and a second trimming module; the bandgap reference core module is used to generate a reference voltage; the output end of the first trimming module is connected to the first adjustment point of the bandgap reference core module, and the first trimming module is used to output a first trimming signal; the first output end of the second trimming module is connected to the second adjustment point of the bandgap reference core module, and the second output end of the second trimming module is connected to the third adjustment point of the bandgap reference core module, and the second trimming module is used to output a second trimming signal; the bandgap reference core module is also used to adjust the reference voltage according to the first trimming signal and the second trimming signal. Among them, the output trimming signals of the first trimming module and the second trimming module are controlled by the signal output by the register. Since the control code can take effect once it is written into the register, the trimming method is simple and convenient, and the trimming speed is fast, which solves the problem of long time-consuming trimming process in the prior art.

[0037] Based on the above embodiment, this embodiment describes the first adjustment module in detail. Figure 3 is a circuit diagram of a first trimming module provided in an embodiment of the present invention, such as Figure 3 As shown, the first adjustment module 120 includes a first switch unit and a second switch unit, the control end of the first switch unit is connected to the first control signal S1, the first end of the first switch unit is connected to the first power supply end V1, and the second end of the first switch unit is connected to the output end a of the first adjustment module 120; the control end of the second switch unit is connected to the second control signal S2, the first end of the second switch unit is connected to the first power supply end V1, and the second end of the second switch unit is connected to the second power supply end V2, the first switch unit is used to turn on or off according to the first control signal S1, and the second switch unit is used to turn on or off according to the second control signal S2, and the first control signal S1 and the second control signal S2 are inverted signals to each other.

[0038] In this embodiment, the first switch unit and the second switch unit are units including switch elements. The first control signal is a signal output by a register (not shown in the figure), and the second control signal is a signal output by the first control signal after being inverted through a NOT gate logic circuit (not shown in the figure). Referring to the above embodiment, the register outputs the first control signal according to the written control code, the NOT gate logic circuit inverts the first control signal and outputs the second control signal, the first switch unit is turned on or off according to the first control signal, the second switch unit is turned on or off according to the second control signal, and the first trimming module 120 outputs the first trimming signal according to the state of the first switch unit and the state of the second switch unit.

[0039] Specifically, the first switch unit includes at least two first transistors Q1, the control ends of the at least two first transistors Q1 are connected to the control end of the first switch unit, the first ends of the at least two first transistors Q1 are connected to the first end of the first switch unit, and the second ends of the at least two first transistors Q1 are connected to the second end of the first switch unit; the second switch unit includes at least two second transistors Q2, the control ends of the at least two second transistors Q2 are connected to the control end of the second switch unit, the first ends of the at least two second transistors Q2 are connected to the first end of the second switch unit, and the second ends of the at least two second transistors Q2 are connected to the second end of the second switch unit. The number of the first transistors Q1 corresponds to the number of the second transistors Q2.

[0040] The first trimming module 120 further includes a third transistor Q3 and a fourth transistor Q4, wherein the control end of the third transistor Q3 is connected to the third power supply end V3, the first end of the third transistor Q3 is connected to the first power supply end V1, the second end of the third transistor Q3 is connected to the output end of the first trimming module 120, the control end of the fourth transistor Q4 is grounded, the first end of the fourth transistor Q4 is connected to the first power supply end V1, the second end of the fourth transistor Q4 is connected to the second power supply end V2, and the first trimming module 120 further includes a twenty-third transistor Q23. The third transistor Q3 is in an off state, the fourth transistor Q4 is in an on state, and the fourth transistor Q4 is used to match at least two first transistors Q1, so that the current distributed in the at least two first transistors Q1 is more accurate.

[0041] Exemplarily, the first switch unit includes eight first transistors Q1 (respectively represented by Q101-Q108) and eight second transistors Q2 (respectively represented by Q201-Q208). The first adjustment module 120 outputs the first control signal and the second control signal through the register and the NOT gate logic circuit. The number of transistors connected in parallel inside the first transistors Q101-Q106 increases by two times. If all the first transistors Q101-Q106 are turned on, the current flowing through the first transistors Q101-Q106 is proportionally distributed at two times the ratio. (The magnitude of the current flowing through the transistor is proportional to the number of transistors connected in parallel. In order to achieve precise control of the current, the first transistors Q101-Q106 are connected in parallel in double proportions, and the number of transistors connected in parallel inside the first transistors Q101-Q106 is 1 2 4 8 respectively. 1632, the first control signal is a binary code, which can realize the adjustment from Im-64Im, where Im is the current flowing when the first transistor Q101 is turned on. In order to keep the current of each transistor of the first transistor Q101-Q108 in a multiple relationship, the fourth transistor Q4 needs to flow a fixed current Im. If Q107 and Q108 continue to use a parallel number of twice the ratio, the current flowing is too large and is not conducive to the matching between transistors. Independent paths can be used to control independent current sources. The first control signal and the second control signal are mutually inverted signals, so that when the input control code is the default state 00000000, the first adjustment module outputs 20uA current), the number of transistors in parallel of the second transistors Q201-Q206 is equal to that of the first transistors Q101-Q106, and the current output by the first power supply terminal V1 is 10uA, which can achieve proportional distribution of 10uA current. The first trimming module 120 also includes the sixth power supply terminal V6 (output current is 10uA) and the seventh power supply terminal V7 (output current is 20uA). The current adjusted by Q107-Q108 and Q207-Q208 is relatively large. If they are connected together with the low position, more tubes are required, and the matching is poor. The use of separate branch control reduces the number of transistors and occupies a smaller chip area. The fourth transistor Q4 flows through the unit current, making the current distribution of each branch more accurate, and the layout is more matched. Since the highest bit is inverted, when the control code of the input register is all 0, the current output by the first trimming module 120 is 20uA, so the first trimming module 120 adjusts the current range to 0-40uA, and the minimum unit current is 0.156uA (40uA / 256). In the default state, the control code of the input register is all 0.

[0042] Based on the above embodiment, this embodiment describes the second adjustment module in detail. Figure 4 is a circuit diagram of a second trimming module provided in an embodiment of the present invention, such as Figure 4As shown, the second trimming module 130 includes a first mirror unit, a third switch unit and a fourth switch unit. The input end of the first mirror unit is connected to the fourth power supply end V4, the first mirror unit is used to provide a bias current, the control end of the third switch unit is connected to the third control signal S3, the first end of the third switch unit is connected to the output end of the first mirror unit, the second end of the third switch unit is connected to the first output end of the second trimming module 130, the control end of the fourth switch unit is connected to the fourth control signal S4, the first end of the fourth switch unit is connected to the output end of the first mirror unit, the second end of the fourth switch unit is connected to the second output end of the second trimming module 130, the third switch unit is used to turn on or off according to the third control signal S3, the fourth switch unit is used to turn on or off according to the fourth control signal S4, and the third control signal S3 and the fourth control signal S4 are inverted signals to each other.

[0043] In this embodiment, the first mirror unit provides bias current for the third switch unit and the fourth switch unit, and the third switch unit and the fourth switch unit are units including switch elements. The third control signal is a signal output by a register (not shown in the figure), and the fourth control signal is a signal output by the third control signal after being inverted through a NOT gate logic circuit (not shown in the figure). Referring to the above embodiment, the register outputs the third control signal according to the written control code, the NOT gate logic circuit inverts the third control signal and outputs the fourth control signal, the third switch unit is turned on or off according to the third control signal, the fourth switch unit is turned on or off according to the fourth control signal, and the second trimming module 130 outputs the second trimming signal according to the state of the third switch unit and the state of the fourth switch unit.

[0044] Specifically, the first mirror unit includes a fifth transistor Q5 and at least two sixth transistors Q6, the first end of the fifth transistor Q5 is connected to the input end of the first mirror unit, the second end of the fifth transistor Q5 is grounded, the control ends of the at least two sixth transistors Q6 are connected to the control end of the fifth transistor Q5, the first ends of the at least two sixth transistors Q6 are connected to the output end of the first mirror unit, and the second ends of the at least two sixth transistors Q6 are grounded.

[0045] In this embodiment, the first end of the fifth transistor Q5 is connected to the fourth power supply terminal V4, the control end of the sixth transistor Q6 is connected to the control end of the fifth transistor Q5, and the sixth transistor Q6 and the fifth transistor Q5 mirror the voltage of the fourth power supply terminal V4 to the first end of the third switch unit and the first end of the fourth switch unit, providing a stable voltage for the third switch unit and the fourth switch unit.

[0046] Specifically, the third switch unit includes at least two seventh transistors Q7, the control ends of the at least two seventh transistors Q7 are connected to the control end of the third switch unit, the first ends of the at least two seventh transistors Q7 are connected to the first end of the third switch unit, and the second ends of the at least two seventh transistors Q7 are connected to the second end of the third switch unit; the fourth switch unit includes at least two eighth transistors Q8, the control ends of the at least two eighth transistors Q8 are connected to the control end of the fourth switch unit, the first ends of the at least two eighth transistors Q8 are connected to the first end of the fourth switch unit, and the second ends of the at least two eighth transistors Q8 are connected to the second end of the fourth switch unit. The number of the seventh transistors Q7 corresponds to the number of the eighth transistors Q8.

[0047] Exemplarily, the first mirror unit includes sixteen sixth transistors Q6, respectively represented by Q601-Q616, and correspondingly, the third switch unit includes sixteen seventh transistors Q7, respectively represented by Q701-Q716, and the fourth switch unit includes sixteen eighth transistors Q8, respectively represented by Q801-Q816. In the default state, the control code of the input register is 0000, which is inverted to 1000 after the high bit is inverted, and then the 16-bit control word "1111111100000000" is obtained after the decoder, so that the number of the seventh transistor Q7 and the eighth transistor Q8 turned on in the default state is equal, that is, the current flowing through the first output end and the second output end of the second trimming module 130 is also equal. When trimming is required, the control code is changed, and the number of transistors turned on by the seventh transistor Q7 and the eighth transistor Q8 changes in the opposite direction (that is, one path increases and the other path decreases), and the magnitude of the current in the two paths also changes in the opposite direction.

[0048] Figure 5 is a circuit diagram of a bandgap reference circuit provided by an embodiment of the present invention, such as Figure 5 As shown, the bandgap reference core module 110 includes an operational amplifier unit, a second mirror unit, a ninth transistor Q9 and a first resistor R1. The operational amplifier unit is used to output a positive temperature coefficient voltage. The second mirror unit is connected to the operational amplifier unit. The second mirror unit is used to replicate the positive temperature coefficient voltage. The first end of the first resistor R1 is connected to the output end of the second mirror unit and the output end of the bandgap reference core module 110. The second end of the first resistor R1 is connected to the first end of the ninth transistor Q9. The second end and the control end of the ninth transistor Q9 are grounded. The ninth transistor Q9 generates a negative temperature coefficient voltage. The first resistor R1 generates a reference voltage Vref according to the positive temperature coefficient voltage output by the second mirror unit and the negative temperature coefficient voltage generated by the ninth transistor Q9.

[0049] In this embodiment, the operational amplifier unit is a unit for transmitting and calculating a signal, and the second mirror unit is a unit for replicating a current in the operational amplifier circuit. On the basis of the above embodiment, the operational amplifier unit outputs a positive temperature coefficient voltage, and the second mirror unit replicates the positive temperature coefficient voltage to the first end of the first resistor R1, and the ninth transistor Q9 generates a negative temperature coefficient voltage. Since the second end of the first resistor R1 is connected to the first end of the ninth transistor Q9, the first resistor R1 generates a reference voltage Vref according to the positive temperature coefficient voltage output by the second mirror unit and the negative temperature coefficient voltage generated by the ninth transistor Q9.

[0050] Specifically, the operational amplifier unit includes a first operational amplifier U1, a second resistor R2, a tenth transistor Q10, an eleventh transistor Q11, a twelfth transistor Q12 and a thirteenth transistor Q13; the first input end of the first operational amplifier U1 is connected to the first end of the tenth transistor Q10 and the second mirror unit, the second input end of the first operational amplifier U1 is connected to the first end of the second resistor R2 and the second mirror unit, the control end of the tenth transistor Q10 is connected to the second adjustment point d and the first end of the eleventh transistor Q11, the second end of the tenth transistor Q10 is connected to the second end of the eleventh transistor Q11, the control end of the eleventh transistor Q11, the second end of the twelfth transistor Q12 and the second end of the thirteenth transistor Q13, the control end of the twelfth transistor Q12 is connected to the control end of the eleventh transistor Q11, and the twelfth transistor Q12 is connected to the control end of the eleventh transistor Q11. The first end of is connected to the third adjustment point f and the control end of the thirteenth transistor Q13, the first end of the thirteenth transistor Q13 is connected to the second end of the second resistor R2; the second mirror unit includes a fourteenth transistor Q14, a fifteenth transistor Q15 and a sixteenth transistor Q16, the first end of the fourteenth transistor Q14 is connected to the first input end of the first operational amplifier U1, the control end of the fourteenth transistor Q14 is connected to the control end of the fifteenth transistor Q15, the control end of the sixteenth transistor Q16 and the output end of the first operational amplifier U1, the second end of the fourteenth transistor Q14 is connected to the second end of the fifteenth transistor Q15, the second end of the sixteenth transistor Q16 and the fifth power supply end V5, the first end of the fifteenth transistor Q15 is connected to the first end of the second resistor R2, and the first end of the sixteenth transistor Q16 is connected to the output end of the second mirror unit.

[0051] In this embodiment, the tenth transistor Q10 and the thirteenth transistor Q13 generate a positive temperature coefficient current IPTAT on the second resistor R2, and the positive temperature coefficient current IPTAT is mirrored to the first resistor R1 through the fifteenth transistor Q15 and the sixteenth transistor Q16 to generate a positive temperature coefficient voltage. The base emitter voltage of the ninth transistor Q9 is a negative temperature coefficient voltage, so the reference voltage Vref is a zero temperature coefficient voltage. According to the "virtual short" characteristic of the first operational amplifier U1, the X point and the Y point are stabilized at approximately equal voltages. Due to asymmetry, the first operational amplifier U1 will be affected by the input "offset" (if the op amp input is zero and its output voltage is not zero). The offset voltage itself changes with temperature, thereby increasing the temperature coefficient of the output voltage. The tenth transistor Q10, the eleventh transistor Q11, the twelfth transistor Q12 and the thirteenth transistor Q13 are in the form of PN junction series connection, which can reduce the influence of the offset voltage.

[0052] On the basis of the above embodiment, the bandgap reference circuit further includes a seventeenth transistor Q17, an eighteenth transistor Q18, a nineteenth transistor Q19, a twentieth transistor Q20, a twenty-first transistor Q21, a twenty-second transistor Q22 and a third resistor R3. Among them, the function of the third resistor R3 is to adjust the source voltage of the twenty-second transistor Q22, change the gate-source voltage of the twenty-second transistor Q22, and change the current I4. The current I4 on the twenty-second transistor Q22 is mirrored to the nineteenth transistor Q19 and the twentieth transistor Q20 branch through the eighteenth transistor Q18, thereby affecting the base-emitter voltage of the eleventh transistor Q11 and the twelfth transistor Q12. Therefore, by adjusting the third resistor R3, the current of the first output terminal and the second output terminal of the second trimming module 130 in the default state can be adjusted, so that the temperature drift of the output reference voltage Vref in the default state is small.

[0053] For example, when no adjustment circuit is added, the output reference voltage expression is:

[0054]

[0055] I0 and I2 are mirror images of the positive temperature coefficient current (current IPTAT):

[0056]

[0057] I S is the transistor saturation current, V T is the transistor conduction threshold voltage, k is the Boltzmann constant (k = 1.38 × 10^-23 J / K), and q is the charge of the electron (q = 1.6 × 10^-19 C).

[0058] m, n, and p are the number of Q2, Q4, and Q5 transistors connected in parallel, respectively. a and b are the mirror ratios of I0 and I2 to the PTAT current.

[0059] After adding the trimming, the trimming currents I1 and I3 are introduced, and the output reference voltage expression is:

[0060]

[0061] After the adjustment current I3 is introduced, I ′ 0 and I ′ 2 is:

[0062]

[0063] I4 is the current generated on M2 and mirrored through M7 and M8.

[0064] Introducing the adjusted reference voltage V R ′ EF Taking the derivative with respect to temperature T yields positive and negative temperature coefficients:

[0065] Negative Temperature Coefficient

[0066] Positive temperature coefficient

[0067] λ is the first-order temperature coefficient. It can be seen from equations (3) and (4) that the current I1 generated by the first trimming module can change the negative temperature coefficient α1, and the current I3 generated by the second trimming module can change the positive temperature coefficient α2 and the negative temperature coefficient α1. The impact on the positive temperature coefficient is relatively large, and the change on the negative temperature coefficient is very small. At the same time, the second trimming module can perform high-order trimming on the negative temperature coefficient.

[0068] Figure 6 It is a curve chart of the adjustment result of the first adjustment module provided by an embodiment of the present invention, wherein the horizontal axis is temperature (in degrees Celsius) and the vertical axis is reference voltage Vref (in volts). When no adjustment is added, the bandgap reference temperature drift is 5.6ppm / °C. In the default state, the injected current is 20uA, the first control signal S1 is between 0 and 127, and the current gradually decreases. When the first control signal S1 is equal to 127, the injected current is at least 0uA, which is the maximum value of the adjusted negative temperature coefficient (absolute value). When the first control signal S1 is equal to 128, the current flowing through is at most 40uA, which is the minimum value of the adjusted negative temperature coefficient (absolute value). When the first control signal S1 is between 128 and 256, the current gradually decreases, and the negative temperature coefficient (absolute value) gradually increases.

[0069] Figure 7It is a curve diagram of the adjustment result of the second adjustment module provided by an embodiment of the present invention, wherein the horizontal axis is temperature (in degrees Celsius) and the vertical axis is reference voltage Vref (in volts). When the third control signal S3 is equal to 0, the currents outputted by the two output terminals of the second adjustment module are equal. When the control code gradually increases, the current at the second output terminal of the second adjustment module increases, and the current at the first output terminal of the second adjustment module decreases. At this time, the positive temperature coefficient increases. When the third control signal S3 is equal to 7, the positive temperature coefficient is maximum. When the third control signal S3 is equal to 8, the current at the second output terminal of the second adjustment module is minimum, and the current at the first output terminal of the second adjustment module is maximum. At this time, the positive temperature coefficient is minimum. When the third control signal S3 is between 8 and 15, the current at the second output terminal of the second adjustment module gradually increases, and the positive temperature coefficient gradually increases.

[0070] The embodiment of the present invention further provides a chip, Figure 8 is a schematic diagram of the structure of a chip provided by an embodiment of the present invention, such as Figure 8 As shown, the chip 10 includes a bandgap reference circuit 100. The bandgap reference circuit 100 can be applied to various chips 10 that require a reference voltage source. For example, the chip 10 includes a power chip, an analog chip (signal chain chips such as ADC chips and DAC chips), and a control chip (FPGA chip, DSP chip, etc.). The chip 10 can be applied to test instruments and equipment. The bandgap reference circuit 100 controls the trimming signal by writing a control code in a register, and has the advantages of a simple structure and a fast trimming speed. At the same time, the bandgap reference circuit 100 has a wide adjustment range and comprehensive coverage, and can perform a wide range of trimming on positive and negative temperature coefficients. Applying the bandgap reference circuit 100 to the chip 10 improves the trimming accuracy of the chip and enhances the stability of the chip at different ambient temperatures.

[0071] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0072] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bandgap reference circuit, characterized in that: It includes a bandgap reference core module, a first trimming module and a second trimming module; The bandgap reference core module is used to generate a reference voltage; The output end of the first trimming module is connected to the first adjustment point of the bandgap reference core module, and the first trimming module is used to output a first trimming signal; The first output end of the second trimming module is connected to the second adjustment point of the bandgap reference core module, the second output end of the second trimming module is connected to the third adjustment point of the bandgap reference core module, and the second trimming module is used to output a second trimming signal; The bandgap reference core module is further configured to adjust the reference voltage according to the first trimming signal and the second trimming signal.

2. The bandgap reference circuit according to claim 1, characterized in that: The first trimming module includes a first switch unit and a second switch unit, the control end of the first switch unit is connected to a first control signal, the first end of the first switch unit is connected to a first power supply end, and the second end of the first switch unit is connected to an output end of the first trimming module; the control end of the second switch unit is connected to a second control signal, the first end of the second switch unit is connected to the first power supply end, and the second end of the second switch unit is connected to the second power supply end, the first switch unit is used to turn on or off according to the first control signal, and the second switch unit is used to turn on or off according to the second control signal, and the first control signal and the second control signal are inverted signals to each other.

3. The bandgap reference circuit according to claim 2, characterized in that: The first switch unit includes at least two first transistors, control ends of the at least two first transistors are connected to the control end of the first switch unit, first ends of the at least two first transistors are connected to the first end of the first switch unit, and second ends of the at least two first transistors are connected to the second end of the first switch unit; The second switch unit includes at least two second transistors, control ends of the at least two second transistors are connected to the control end of the second switch unit, first ends of the at least two second transistors are connected to the first end of the second switch unit, and second ends of the at least two second transistors are connected to the second end of the second switch unit.

4. The bandgap reference circuit according to claim 2, characterized in that: The first trimming module also includes a third transistor and a fourth transistor, the control end of the third transistor is connected to the third power supply end, the first end of the third transistor is connected to the first power supply end, the second end of the third transistor is connected to the output end of the first trimming module, the control end of the fourth transistor is grounded, the first end of the fourth transistor is connected to the first power supply end, and the second end of the fourth transistor is connected to the second power supply end.

5. The bandgap reference circuit according to claim 1, characterized in that: The second trimming module includes a first mirror unit, a third switch unit and a fourth switch unit. The input end of the first mirror unit is connected to the fourth power supply end. The first mirror unit is used to provide a bias current. The control end of the third switch unit is connected to a third control signal. The first end of the third switch unit is connected to the output end of the first mirror unit. The second end of the third switch unit is connected to the first output end of the second trimming module. The control end of the fourth switch unit is connected to a fourth control signal. The first end of the fourth switch unit is connected to the output end of the first mirror unit. The second end of the fourth switch unit is connected to the second output end of the second trimming module. The third switch unit is used to turn on or off according to the third control signal. The fourth switch unit is used to turn on or off according to the fourth control signal. The third control signal and the fourth control signal are inverted signals.

6. The bandgap reference circuit according to claim 5, characterized in that: The first mirror unit includes a fifth transistor and at least two sixth transistors, wherein a first end of the fifth transistor is connected to an input end of the first mirror unit, a second end of the fifth transistor is grounded, control ends of the at least two sixth transistors are connected to a control end of the fifth transistor, a first end of the at least two sixth transistors is connected to an output end of the first mirror unit, and a second end of the at least two sixth transistors is grounded.

7. The bandgap reference circuit according to claim 5, characterized in that: The third switch unit includes at least two seventh transistors, control ends of the at least two seventh transistors are connected to the control end of the third switch unit, first ends of the at least two seventh transistors are connected to the first end of the third switch unit, and second ends of the at least two seventh transistors are connected to the second end of the third switch unit; The fourth switch unit includes at least two eighth transistors, the control ends of the at least two eighth transistors are connected to the control end of the fourth switch unit, the first ends of the at least two eighth transistors are connected to the first end of the fourth switch unit, and the second ends of the at least two eighth transistors are connected to the second end of the fourth switch unit.

8. The bandgap reference circuit according to claim 1, characterized in that: The bandgap reference core module includes an operational amplifier unit, a second mirror unit, a ninth transistor and a first resistor, wherein the operational amplifier unit is used to output a positive temperature coefficient voltage, the second mirror unit is connected to the operational amplifier unit, the second mirror unit is used to replicate the positive temperature coefficient voltage, the first end of the first resistor is connected to the output end of the second mirror unit and the output end of the bandgap reference core module, the second end of the first resistor is connected to the first end of the ninth transistor, the second end and the control end of the ninth transistor are grounded, the ninth transistor generates a negative temperature coefficient voltage, and the first resistor generates the reference voltage according to the positive temperature coefficient voltage output by the second mirror unit and the negative temperature coefficient voltage generated by the ninth transistor.

9. The bandgap reference circuit according to claim 8, characterized in that: The operational amplifier unit includes a first operational amplifier, a second resistor, a tenth transistor, an eleventh transistor, a twelfth transistor and a thirteenth transistor; the first input end of the first operational amplifier is connected to the first end of the tenth transistor and the second mirror unit, the second input end of the first operational amplifier is connected to the first end of the second resistor and the second mirror unit, the control end of the tenth transistor is connected to the second adjustment point and the first end of the eleventh transistor, the second end of the tenth transistor is connected to the second end of the eleventh transistor, the control end of the eleventh transistor, the second end of the twelfth transistor and the second end of the thirteenth transistor, the control end of the twelfth transistor is connected to the control end of the eleventh transistor, the first end of the twelfth transistor is connected to the third adjustment point and the control end of the thirteenth transistor, and the first end of the thirteenth transistor is connected to the second end of the second resistor; The second mirror unit includes a fourteenth transistor, a fifteenth transistor and a sixteenth transistor, the first end of the fourteenth transistor is connected to the first input end of the first operational amplifier, the control end of the fourteenth transistor is connected to the control end of the fifteenth transistor, the control end of the sixteenth transistor and the output end of the first operational amplifier, the second end of the fourteenth transistor is connected to the second end of the fifteenth transistor, the second end of the sixteenth transistor and a fifth power supply end, the first end of the fifteenth transistor is connected to the first end of the second resistor, and the first end of the sixteenth transistor is connected to the output end of the second mirror unit.

10. A chip, characterized in that: The invention comprises the bandgap reference circuit as described in any one of claims 1 to 9.

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