Curvature Corrected Bandgap Reference Circuit

Abstract

The present invention provides a curvature-corrected bandgap reference circuit, which includes a bandgap reference module, a low-temperature curvature correction module, and a high-temperature curvature correction module. The bandgap reference module generates a bandgap reference voltage by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage. The low-temperature curvature correction module compensates and adjusts the positive temperature coefficient voltage to correct the low-temperature curvature of the bandgap reference voltage. The high-temperature curvature correction module compensates and adjusts the positive temperature coefficient voltage to correct the high-temperature curvature of the bandgap reference voltage, further reducing the temperature drift coefficient of the bandgap reference voltage and improving the temperature stability of the bandgap reference voltage. An adjusting resistor is introduced to balance the curvature correction compensation degree at low and high temperatures, further improving performance. At the same time, the curvature-corrected bandgap reference circuit proposed by the present invention can be used in a relatively low power supply voltage environment and is suitable for advanced CMOS processes of 28nm and below.

Description

Technical Field

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

[0002] Bandgap reference circuits are widely used in various analog and mixed-signal integrated circuits due to their ability to generate high-precision and high-stability bandgap reference voltages. However, in advanced 28nm CMOS processes, the design of bandgap reference circuits is becoming increasingly difficult due to decreasing power supply voltages and increasing temperature variations. Furthermore, the higher performance requirements of products using advanced processes further increase the performance demands placed on bandgap reference circuits.

[0003] Traditional bandgap reference circuits are generally constructed using the principle of mutual compensation between positive and negative temperature coefficients. Although this compensation method can greatly reduce the impact of temperature on the output bandgap reference voltage, the voltage difference between intermediate temperatures and high and low temperatures is still large, making it impossible to obtain a bandgap reference voltage with smaller temperature variation, which will affect the performance of some high-performance modules. At the same time, for advanced CMOS processes of 28nm and below, due to their relatively low power supply voltage (such as 1.9V), traditional bandgap reference circuits cannot operate at lower power supply voltages.

[0004] Therefore, there is an urgent need for a high-performance bandgap reference circuit technology solution that can be applied to low power supply voltages. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a technical solution for a curvature-corrected bandgap reference circuit. On the basis of the traditional bandgap reference compensation circuit, a low-temperature curvature correction module and a high-temperature curvature correction module are added to correct the low-temperature curvature and high-temperature curvature of the bandgap reference voltage respectively, thereby reducing the temperature drift coefficient of the bandgap reference voltage; at the same time, an adjustment resistor is introduced to balance the curvature correction compensation degree at low temperature and high temperature, thereby further improving performance.

[0006] To achieve the above-mentioned objectives and other related objectives, the present invention provides the following technical solutions.

[0007] A curvature-corrected bandgap reference circuit, comprising:

[0008] The bandgap reference module generates and outputs a bandgap reference voltage by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage;

[0009] a low-temperature curvature correction module, connected to the bandgap reference module, for compensating and adjusting the positive temperature coefficient voltage to correct the low-temperature curvature of the bandgap reference voltage;

[0010] The high-temperature curvature correction module is connected to the bandgap reference module and performs compensation adjustment on the positive temperature coefficient voltage to correct the high-temperature curvature of the bandgap reference voltage.

[0011] Optionally, the bandgap reference module includes a bandgap reference unit, an output drive unit and a frequency compensation unit, the bandgap reference unit generates and outputs the bandgap reference voltage, the output drive unit is connected to the bandgap reference unit, the output drive unit provides a driving current for the bandgap reference unit, the frequency compensation unit is connected to the bandgap reference unit, and the frequency compensation unit compensates and adjusts the output frequency of the bandgap reference unit.

[0012] Optionally, the bandgap reference unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first NPN transistor, a second NPN transistor and an operational amplifier, the emitter of the first NPN transistor is connected to ground after being connected in series with the first resistor and the second resistor, the collector of the first NPN transistor is connected to the base of the first NPN transistor after being connected in series with the third resistor, the emitter of the second NPN transistor is connected to the common end of the first resistor and the second resistor, the collector of the second NPN transistor is connected to the base of the first NPN transistor after being connected in series with the fourth resistor, the base of the second NPN transistor is connected to the base of the first NPN transistor, the non-inverting input terminal of the operational amplifier is connected to the collector of the first NPN transistor, the inverting input terminal of the operational amplifier is connected to the collector of the second NPN transistor, and the base of the first NPN transistor outputs the bandgap reference voltage.

[0013] Optionally, the resistance of the third resistor is equal to the resistance of the fourth resistor, the emitter junction area of ​​the first NPN transistor is N times the emitter junction area of ​​the second NPN transistor, and N is an integer greater than or equal to 1.

[0014] Optionally, the output drive unit includes a fifth resistor and a PMOS tube, the source of the PMOS tube is connected to the power supply voltage, the gate of the PMOS tube is connected to the output end of the operational amplifier, the drain of the PMOS tube is grounded after passing through the fifth resistor connected in series, the drain of the PMOS tube is also connected to the base of the first NPN transistor, and the drain of the PMOS tube outputs the driving current.

[0015] Optionally, the frequency compensation unit includes a sixth resistor and a capacitor, one end of the sixth resistor is connected to the gate of the PMOS tube, the other end of the sixth resistor is connected to one end of the capacitor, and the other end of the capacitor is connected to the drain of the PMOS tube.

[0016] Optionally, the low-temperature curvature correction module includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor and a third NPN transistor. The base of the first NPN transistor is grounded after being connected in series with the seventh resistor and the eighth resistor, the collector of the third NPN transistor is connected to the base of the first NPN transistor after being connected in series with the ninth resistor, the collector of the third NPN transistor is also connected to the emitter of the first NPN transistor, the base of the third NPN transistor is connected to the common end of the seventh resistor and the eighth resistor, and the emitter of the third NPN transistor is grounded after being connected in series with the tenth resistor.

[0017] Optionally, the low-temperature curvature correction module further includes an eleventh resistor, one end of the eleventh resistor is connected to the base of the first NPN transistor, and the other end of the eleventh resistor is connected to the emitter of the first NPN transistor.

[0018] Optionally, the high-temperature curvature correction module includes a fourth NPN transistor and a fifth NPN transistor, the collector of the fourth NPN transistor is connected to the collector of the first NPN transistor, the emitter of the fourth NPN transistor is connected to the base of the first NPN transistor, the base of the fourth NPN transistor is connected to the emitter of the fourth NPN transistor, the collector of the fifth NPN transistor is connected to the collector of the second NPN transistor, the emitter of the fifth NPN transistor is connected to the base of the first NPN transistor, and the base of the fifth NPN transistor is connected to the emitter of the fifth NPN transistor.

[0019] Optionally, a size of the fifth NPN transistor is larger than a size of the fourth NPN transistor.

[0020] As described above, the curvature-corrected bandgap reference circuit provided by the present invention has at least the following beneficial effects:

[0021] A bandgap reference circuit with curvature correction is designed by combining a bandgap reference module, a low-temperature curvature correction module and a high-temperature curvature correction module. On the basis that the bandgap reference module generates a bandgap reference voltage by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage, the positive temperature coefficient voltage is compensated and adjusted by the low-temperature curvature correction module, which can correct the low-temperature curvature of the bandgap reference voltage. The positive temperature coefficient voltage is compensated and adjusted by the high-temperature curvature correction module, which can correct the high-temperature curvature of the bandgap reference voltage. The temperature drift coefficient of the bandgap reference voltage can be further reduced, thereby improving the temperature stability of the bandgap reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is the circuit diagram of a conventional bandgap reference circuit.

[0023] Figure 2A simulation curve showing the variation of the bandgap reference voltage outputted by a conventional bandgap reference circuit with temperature.

[0024] Figure 3 Shown is a circuit diagram of the curvature-corrected bandgap reference circuit of the present invention.

[0025] Figure 4 Shown is a simulation curve showing the variation of the bandgap reference voltage output by the curvature-corrected bandgap reference circuit of the present invention with temperature.

[0026] Description of Reference Numerals

[0027] 1—bandgap reference module, 2—low-temperature curvature correction module, 3—high-temperature curvature correction module, M1~M3—NMOS transistors, M4~M7, P1—PMOS transistors, IBIAS—bias current, Q1—first NPN transistor, Q2—second NPN transistor, Q3—third NPN transistor, Q4—fourth NPN transistor, Q5—fifth NPN transistor, R1—first resistor, R2—second resistor, R3—third resistor, R4—fourth resistor, R5—fifth resistor, R6—sixth resistor, R7—seventh resistor, R8—eighth resistor, R9—ninth resistor, R10—tenth resistor, R11—eleventh resistor, C1—capacitor, AMP1—operational amplifier, VDD—power supply voltage, GND—ground, VBANDGEN, VBG—bandgap reference voltage. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] See also Figures 1-4 . It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner, so the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components during actual implementation. During actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated. The structure, proportion, size, etc. shown in the diagrams attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0030] As mentioned above in the background technology, Figure 1 As shown, a conventional bandgap reference circuit is generally constructed using the principle of mutual compensation of positive temperature coefficient and negative temperature coefficient. It is composed of NMOS transistors M1 to M3, PMOS transistors M4 to M7, a first NPN transistor Q1, a second NPN transistor Q2, a first resistor R1, and a second resistor R2. The bias current IBIAS provides bias for the PMOS transistors M6 to M7, and the power supply voltage VDD and the ground GND provide power for the bandgap reference circuit. The individual dimensions of the first NPN transistor Q1 and the second NPN transistor Q2 are consistent, but the first The number of NPN transistors Q1 is N times that of the second NPN transistors Q2 (or in other words, the emitter junction cross-sectional area of ​​the first NPN transistor Q1 is N times the emitter junction cross-sectional area of ​​the second NPN transistor Q2, where N is an integer greater than or equal to 1). The currents flowing through the first NPN transistor Q1 and the second NPN transistor Q2 are pulled to be consistent through a current mirror formed by PMOS transistors M4 and M5. The NMOS transistor M1 is used to control the emitter voltage of the first NPN transistor Q1, and the NMOS transistor M2 is used to control the emitter voltage of the second NPN transistor Q2.

[0031] In this way, a positive temperature coefficient voltage and a negative temperature coefficient voltage can be simultaneously formed through the first NPN transistor Q1 and the second NPN transistor Q2 to achieve a compensation effect. Assume that the current flowing through the first NPN transistor Q1 is IC1, the current flowing through the second NPN transistor Q2 is IC2, the base-collector voltage difference of the first NPN transistor Q1 is VBE1, and the base-collector voltage difference of the second NPN transistor Q2 is VBE2.

[0032] Then by Figure 1 have

[0033] VBE2-VBE1=IC1·R1

[0034] For the base-collector voltage difference of a transistor, we can write it in the form of a current expression as follows:

[0035]

[0036] Where VT is the thermal voltage and IS is the reverse saturation current;

[0037] So there is

[0038]

[0039] Right now

[0040]

[0041] For the output voltage of the bandgap reference circuit (i.e., the bandgap reference voltage) VBANDGEN, there is

[0042] (IC1+IC2)·R2+VBE2=VBANDGEN

[0043] Due to the current mirror effect formed by PMOS tubes M4 and M5, IC1 = IC2, so

[0044]

[0045] Since the number of the first NPN transistor Q1 is N times that of the second NPN transistor Q2 (or the emitter junction cross-sectional area of ​​the first NPN transistor Q1 is N times that of the emitter junction cross-sectional area of ​​the second NPN transistor Q2), IS1≈N*IS2, substituting into the above formula, we have

[0046]

[0047] The above bandgap reference voltage formula includes the positive temperature coefficient term VT and the negative temperature coefficient term VBE2. As long as the resistance values ​​of the first resistor R1 and the second resistor R2 are adjusted to appropriate values, we can obtain a temperature-voltage curve similar to a parabola. The simulation results are as follows: Figure 2 As shown, its temperature drift coefficient is 35.04ppm.

[0048] In this way, if Figure 1 The conventional bandgap reference circuit shown above utilizes the principle of mutual compensation between the positive temperature coefficient term VT and the negative temperature coefficient term VBE2 to produce a bandgap reference voltage with minimal temperature variation. While this compensation method can significantly reduce the impact of temperature on the output bandgap reference voltage, the resulting temperature-voltage curves, derived solely through mutual compensation between the positive temperature coefficient term VT and the negative temperature coefficient term VBE2, still exhibit significant voltage differences between high temperatures (e.g., 125°C), low temperatures (e.g., -40°C), and intermediate temperatures (e.g., 55°C). This fails to produce a bandgap reference voltage with minimal temperature variation. This can affect the performance of certain high-performance modules (such as ADCs, DACs, and PLLs), resulting in poor performance at high or low temperatures. Furthermore, for advanced CMOS processes of 28nm and below, the traditional bandgap reference circuit cannot operate at these relatively low supply voltages (e.g., 1.9V), making it unsuitable.

[0049] Based on this, the present invention proposes a technical solution for a curvature-corrected bandgap reference circuit: on the basis of a traditional bandgap reference compensation circuit, a low-temperature curvature correction module and a high-temperature curvature correction module are added to correct the low-temperature curvature and high-temperature curvature of the bandgap reference voltage respectively, thereby reducing the temperature drift coefficient of the bandgap reference voltage; at the same time, an adjustment resistor is introduced to balance the curvature correction compensation degree at low and high temperatures, thereby further improving performance.

[0050] like Figure 3 As shown, the present invention proposes a curvature correction bandgap reference circuit, which includes:

[0051] The bandgap reference module 1 generates and outputs a bandgap reference voltage VBG by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage;

[0052] The low-temperature curvature correction module 2 is connected to the bandgap reference module 1 and performs compensation adjustment on the positive temperature coefficient voltage to correct the low-temperature curvature of the bandgap reference voltage VBG;

[0053] The high-temperature curvature correction module 3 is connected to the bandgap reference module 1 and performs compensation adjustment on the positive temperature coefficient voltage to correct the high-temperature curvature of the bandgap reference voltage VBG.

[0054] In detail, such as Figure 3 As shown, the bandgap reference module 1 includes a bandgap reference unit, an output driving unit and a frequency compensation unit. The bandgap reference unit generates and outputs a bandgap reference voltage VBG. The output driving unit is connected to the bandgap reference unit and provides a driving current for the bandgap reference unit. The frequency compensation unit is connected to the bandgap reference unit and compensates and adjusts the output frequency of the bandgap reference unit.

[0055] In more detail, Figure 3 As shown, the bandgap reference unit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first NPN transistor Q1, a second NPN transistor Q2 and an operational amplifier AMP1. The emitter of the first NPN transistor Q1 is connected to the ground GND through the first resistor R1 and the second resistor R2 connected in series. The collector of the first NPN transistor Q1 is connected to the base of the first NPN transistor Q1 through the third resistor R3 connected in series. The emitter of the second NPN transistor Q2 is connected to the first resistor R1 and the second resistor R2 connected in series. The common end of the resistor R1 and the second resistor R2, the collector of the second NPN transistor Q2 is connected to the base of the first NPN transistor Q1 after being connected in series with the fourth resistor R4, the base of the second NPN transistor Q2 is connected to the base of the first NPN transistor Q1, the non-inverting input end of the operational amplifier AMP1 is connected to the collector of the first NPN transistor Q1, the inverting input end of the operational amplifier AMP1 is connected to the collector of the second NPN transistor Q2, and the base of the first NPN transistor Q1 outputs the bandgap reference voltage VBG.

[0056] In which, the resistance of the third resistor R3 is equal to the resistance of the fourth resistor R4, the emitter junction area of ​​the first NPN transistor Q1 is N times the emitter junction area of ​​the second NPN transistor Q2, or the number of first NPN transistors Q1 is N times the number of second NPN transistors Q2, that is, the first NPN transistor Q1 is actually a device formed by N second NPN transistors Q2 connected in parallel, where N is an integer greater than or equal to 1.

[0057] In more detail, Figure 3 As shown, the output driving unit includes a fifth resistor R5 and a PMOS transistor P1. The source of the PMOS transistor P1 is connected to the power supply voltage VDD, the gate of the PMOS transistor P1 is connected to the output terminal of the operational amplifier AMP1, and the drain of the PMOS transistor P1 is connected to the ground GND after passing through the fifth resistor R5 connected in series. The drain of the PMOS transistor P1 is also connected to the base of the first NPN transistor Q1. The drain of the PMOS transistor P1 outputs a driving current.

[0058] In more detail, Figure 3 As shown, the frequency compensation unit includes a sixth resistor R6 and a capacitor C1. One end of the sixth resistor R6 is connected to the gate of the PMOS transistor P1. The other end of the sixth resistor R6 is connected to one end of the capacitor C1. The other end of the capacitor C1 is connected to the drain of the PMOS transistor P1.

[0059] In detail, such as Figure 3 As shown, the low-temperature curvature correction module 2 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and a third NPN transistor Q3. The base of the first NPN transistor Q3 is connected to the ground GND via the seventh resistor R7 and the eighth resistor R8 connected in series. The collector of the third NPN transistor Q3 is connected to the base of the first NPN transistor Q1 via the ninth resistor R9 connected in series. The collector of the third NPN transistor Q3 is also connected to the emitter of the first NPN transistor Q1. The base of the third NPN transistor Q3 is connected to the common end of the seventh resistor R7 and the eighth resistor R8. The emitter of the third NPN transistor Q3 is connected to the ground GND via the tenth resistor R10 connected in series.

[0060] In detail, such as Figure 3 As shown, the low-temperature curvature correction module 2 further includes an eleventh resistor R11 , one end of the eleventh resistor R11 is connected to the base of the first NPN transistor Q1 , and the other end of the eleventh resistor R11 is connected to the emitter of the first NPN transistor Q1 .

[0061] In detail, such as Figure 3As shown, the high-temperature curvature correction module 3 includes a fourth NPN transistor Q4 and a fifth NPN transistor Q5. The collector of the fourth NPN transistor Q4 is connected to the collector of the first NPN transistor Q1, the emitter of the fourth NPN transistor Q4 is connected to the base of the first NPN transistor Q1, the base of the fourth NPN transistor Q4 is connected to the emitter of the fourth NPN transistor Q4, the collector of the fifth NPN transistor Q5 is connected to the collector of the second NPN transistor Q2, the emitter of the fifth NPN transistor Q5 is connected to the base of the first NPN transistor Q1, and the base of the fifth NPN transistor Q5 is connected to the emitter of the fifth NPN transistor Q5.

[0062] The size of the fifth NPN transistor Q5 is larger than that of the fourth NPN transistor Q4 , and the size of the fifth NPN transistor Q5 is much larger than that of the fourth NPN transistor Q4 .

[0063] In more detail, Figure 3 The working principle of the curvature-corrected bandgap reference circuit shown is analyzed as follows.

[0064] 1) The basic principle of the bandgap reference unit in the bandgap reference module 1 is the same as that of the traditional bandgap reference circuit. The collector of the first NPN transistor Q1 and the collector of the second NPN transistor Q2 are pulled to the same value through the operational amplifier AMP1. Since the resistance of the third resistor R3 is equal to the resistance of the fourth resistor R4, when the value of the bandgap reference voltage VBG output by the bandgap reference unit stabilizes, the current IC1 flowing through the first NPN transistor Q1 and the current IC2 flowing through the second NPN transistor Q2 are the same. Therefore, the bandgap reference voltage VBG has the following expression.

[0065]

[0066]

[0067] Similarly, the emitter junction area of ​​the first NPN transistor Q1 is N times the emitter junction area of ​​the second NPN transistor Q2, so that IS1≈N*IS2, and the expression can be approximated as follows:

[0068]

[0069] Among them, VT has a positive temperature coefficient, VBE2 has a negative temperature coefficient, the first term of the above formula is the positive temperature coefficient voltage, and the second term of the above formula is the negative temperature coefficient voltage. Therefore, in the bandgap reference module 1, the bandgap reference unit generates and outputs the bandgap reference voltage VBG by superimposing the positive temperature coefficient voltage and the negative temperature coefficient voltage.

[0070] In the bandgap reference module 1, the PMOS transistor P1 and the fifth resistor R5 form an output drive unit. The output drive unit forms feedback with the bandgap reference unit. Under the output control of the operational amplifier AMP1, the output end of the bandgap reference voltage VBG is provided with sufficient drive current to ensure the normal operation of the bandgap reference unit. The sixth resistor R6 and the capacitor C1 form a frequency compensation unit, which is connected to the output end of the operational amplifier AMP1 to compensate and adjust the output frequency of the operational amplifier AMP1.

[0071] 2) For the low-temperature curvature correction module 2, since the bandgap reference voltage VBG varies minimally with temperature, the base voltages of the third NPN transistor Q3 and the first NPN transistor Q1 remain essentially unchanged. Because the transistor's base-collector voltage difference VBE has a negative temperature coefficient, the emitter voltage of the first NPN transistor Q1 increases with increasing temperature. Similarly, the emitter voltage of the third NPN transistor Q3 also increases with increasing temperature. When the temperature is low, the base voltage of the third NPN transistor Q3 is biased to an appropriate value through the seventh resistor R7 and the eighth resistor R8. At this time, due to the low emitter voltage of the third NPN transistor Q3, the current flowing through the third NPN transistor Q3 (or the tenth resistor R10) is at a very low value. Therefore, the current flowing through the ninth resistor R9 is diverted away from the first resistor R1, thereby increasing the emitter voltage of the first NPN transistor Q1, or in other words, increasing the current flowing through the second resistor R2 (positively correlated with the positive temperature coefficient voltage in the formula), slightly increasing the base voltage of the first NPN transistor Q1 (i.e., the bandgap reference voltage VBG). As the temperature rises, the emitter voltage of the third NPN transistor Q3 increases, and the current flowing through the third NPN transistor Q3 gradually increases. At the same time, the emitter voltage of the first NPN transistor Q1 increases, while the bandgap reference voltage VBG does not change, so the current flowing through the ninth resistor R9 decreases. The current flowing through the ninth resistor R9 decreases, while the current flowing through the third NPN transistor Q3 increases. This causes the current flowing from the ninth resistor R9 to the first resistor R1 to decrease and approach zero. Therefore, as the temperature rises, the compensation provided by the low-temperature curvature correction module 2 gradually decreases until almost no compensation is provided, allowing the low-temperature curvature correction module 2 to effectively perform the low-temperature curvature correction function.

[0072] 3) Regarding the high-temperature curvature correction module 3, since the emitter and base of the fourth NPN transistor Q4 are respectively connected to the bandgap reference voltage VBG, the emitter and base of the fifth NPN transistor Q5 are respectively connected to the bandgap reference voltage VBG, the collector of the first NPN transistor Q1 is connected to the collector of the fourth NPN transistor Q4, and the collector of the second NPN transistor Q2 is connected to the collector of the fifth NPN transistor Q5, the fourth NPN transistor Q4 and the fifth NPN transistor Q5 are therefore inverted transistors operating in the cutoff region. In this operating state, the electron diffusion current (i.e., IBE current) formed by electrons injected from the base region into the emitter region, that is, the base-to-collector current, always exists. This current is not significant at low temperatures, but begins to take effect when the temperature rises to a certain level. Since the size of the fifth NPN transistor Q5 is much larger than that of the fourth NPN transistor Q4, when the collector voltage of the fourth NPN transistor Q4 and the collector voltage of the fifth NPN transistor Q5 are pulled to the same level by the operational amplifier AMP1, the current flowing from the base region to the collector of the fifth NPN transistor Q5 will be larger than the current flowing from the base region to the collector of the fourth NPN transistor Q4, thereby causing the current IC2 flowing through the second NPN transistor Q2 to be larger than the current IC1 flowing through the first NPN transistor Q1. Since the first NPN transistor Q1 and the second NPN transistor Q2 satisfy the following expression when the high-temperature curvature correction module 3 composed of the fourth NPN transistor Q4 and the fifth NPN transistor Q5 is not added

[0073]

[0074] Therefore, after adding the high-temperature curvature correction module 3 consisting of the fourth NPN transistor Q4 and the fifth NPN transistor Q5, the current IC2 flowing through the second NPN transistor Q2 is slightly larger than the current IC1 flowing through the first NPN transistor Q1, which increases the positive temperature coefficient voltage in the formula and causes the bandgap reference voltage VBG to increase, thereby compensating for the bandgap reference voltage VBG at high temperatures. As the temperature decreases, the emitter-collector voltage difference between the fourth NPN transistor Q4 and the fifth NPN transistor Q5 gradually decreases, and the reverse cutoff current in the fourth NPN transistor Q4 and the fifth NPN transistor Q5 gradually decreases until there is no reverse cutoff current. The compensation of the high-temperature curvature correction module 3 gradually decreases until almost no compensation is generated, allowing the high-temperature curvature correction module 3 to achieve the high-temperature curvature correction function.

[0075] 4) Based on the bandgap reference voltage VBG generated by superimposing the positive temperature coefficient voltage and the negative temperature coefficient voltage in the bandgap reference module 1, the low-temperature curvature of the bandgap reference voltage VBG is corrected by the low-temperature curvature correction module 2, and the high-temperature curvature of the bandgap reference voltage VBG is corrected by the high-temperature curvature correction module 3. It should be noted that the low-temperature curvature refers to the curvature within a specified low-temperature range (e.g., -40°C to 0°C), and the high-temperature curvature refers to the curvature within a specified high-temperature range (e.g., 80°C to 120°C), which are not limited here.

[0076] 5) After simultaneously applying the low-temperature curvature correction module 2 and the high-temperature curvature correction module 3 to correct the temperature curvature of the bandgap reference voltage VBG, in order to balance the degree of the two corrections, the present invention adds an eleventh resistor R11. The eleventh resistor R11 serves as an adjustment resistor. By adjusting the value of the eleventh resistor R11, the compensation effect of the third NPN transistor Q3 can be modified to a certain extent. The smaller the resistance of the eleventh resistor R11, the greater the current flowing into the first resistor R1, which in turn increases the compensation effect of the third NPN transistor Q3. To ensure that the eleventh resistor R11 does not disrupt the normal operation of the bandgap reference, the resistance of the eleventh resistor R11 is typically relatively large, ranging from hundreds of kilohms to megaohms.

[0077] In an optional embodiment of the present invention, in order to verify the advantages of the curvature correction bandgap reference circuit of the present invention, the curvature correction bandgap reference circuit proposed by the present invention is designed and implemented in a 28nm CMOS process using 1.9V as the power supply voltage VDD. In order to minimize noise and improve performance, the operational amplifier AMP1 uses a triode as the input pair transistor to ensure a low-frequency gain of about 90dB. The circuit is constructed and simulated, and the simulation results are as follows: Figure 4 As shown in the figure, it can be seen that the temperature drift coefficient of the corresponding bandgap reference voltage is only 4.712ppm, which is consistent with Figure 2 Compared with the simulation results of the traditional bandgap reference circuit, its temperature drift coefficient is reduced by nearly 8 times, which fully demonstrates the performance improvement effect of the curvature correction bandgap reference circuit in the present invention.

[0078] In summary, in the curvature-corrected bandgap reference circuit provided by the present invention, a bandgap reference circuit with curvature correction is designed by combining a bandgap reference module, a low-temperature curvature correction module and a high-temperature curvature correction module. On the basis of the bandgap reference module generating a bandgap reference voltage by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage, the positive temperature coefficient voltage is compensated and adjusted by the low-temperature curvature correction module, so that the low-temperature curvature of the bandgap reference voltage can be corrected. The positive temperature coefficient voltage is compensated and adjusted by the high-temperature curvature correction module, so that the high-temperature curvature of the bandgap reference voltage can be corrected, and the temperature drift coefficient of the bandgap reference voltage can be further reduced, thereby improving the temperature stability of the bandgap reference voltage. An adjusting resistor is introduced to balance the curvature correction compensation degree at low and high temperatures, thereby further improving the performance. At the same time, the curvature-corrected bandgap reference circuit proposed by the present invention can be applied in a lower power supply voltage environment and is suitable for advanced CMOS processes of 28nm and below.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A curvature-corrected bandgap reference circuit, characterized in that: include: The bandgap reference module generates and outputs a bandgap reference voltage by superimposing a positive temperature coefficient voltage and a negative temperature coefficient voltage; the bandgap reference module includes a bandgap reference unit, an output drive unit and a frequency compensation unit, the bandgap reference unit generates and outputs the bandgap reference voltage, the output drive unit is connected to the bandgap reference unit, the output drive unit provides a drive current for the bandgap reference unit, the frequency compensation unit is connected to the bandgap reference unit, and the frequency compensation unit compensates and adjusts the output frequency of the bandgap reference unit; the bandgap reference unit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first NPN transistor, a second NPN transistor and an operational amplifier, the first NPN transistor The emitter of the first transistor is connected to ground via the first resistor and the second resistor connected in series in sequence, the collector of the first NPN transistor is connected to the base of the first NPN transistor via the third resistor connected in series, the emitter of the second NPN transistor is connected to the common end of the first resistor and the second resistor, the collector of the second NPN transistor is connected to the base of the first NPN transistor via the fourth resistor connected in series, the base of the second NPN transistor is connected to the base of the first NPN transistor, the non-inverting input terminal of the operational amplifier is connected to the collector of the first NPN transistor, the inverting input terminal of the operational amplifier is connected to the collector of the second NPN transistor, and the base of the first NPN transistor outputs the bandgap reference voltage; a low-temperature curvature correction module, connected to the bandgap reference module, compensating and adjusting the positive temperature coefficient voltage to correct the low-temperature curvature of the bandgap reference voltage; the low-temperature curvature correction module includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, and a third NPN transistor, wherein the base of the first NPN transistor is connected to ground via the seventh resistor and the eighth resistor connected in series, the collector of the third NPN transistor is connected to the base of the first NPN transistor via the ninth resistor connected in series, the collector of the third NPN transistor is also connected to the emitter of the first NPN transistor, the base of the third NPN transistor is connected to a common end of the seventh resistor and the eighth resistor, and the emitter of the third NPN transistor is grounded via the tenth resistor connected in series; A high-temperature curvature correction module is connected to the bandgap reference module to compensate and adjust the positive temperature coefficient voltage to correct the high-temperature curvature of the bandgap reference voltage; the high-temperature curvature correction module includes a fourth NPN transistor and a fifth NPN transistor, the collector of the fourth NPN transistor is connected to the collector of the first NPN transistor, the emitter of the fourth NPN transistor is connected to the base of the first NPN transistor, the base of the fourth NPN transistor is connected to the emitter of the fourth NPN transistor, the collector of the fifth NPN transistor is connected to the collector of the second NPN transistor, the emitter of the fifth NPN transistor is connected to the base of the first NPN transistor, and the base of the fifth NPN transistor is connected to the emitter of the fifth NPN transistor.

2. The curvature-corrected bandgap reference circuit according to claim 1, wherein: The resistance of the third resistor is equal to the resistance of the fourth resistor, the emitter junction area of ​​the first NPN transistor is N times the emitter junction area of ​​the second NPN transistor, and N is an integer greater than or equal to 1.

3. The curvature-corrected bandgap reference circuit according to claim 1, wherein: The output drive unit includes a fifth resistor and a PMOS transistor, the source of the PMOS transistor is connected to the power supply voltage, the gate of the PMOS transistor is connected to the output end of the operational amplifier, the drain of the PMOS transistor is grounded after passing through the fifth resistor connected in series, the drain of the PMOS transistor is also connected to the base of the first NPN transistor, and the drain of the PMOS transistor outputs the driving current.

4. The curvature-corrected bandgap reference circuit according to claim 3, wherein: The frequency compensation unit includes a sixth resistor and a capacitor, one end of the sixth resistor is connected to the gate of the PMOS tube, the other end of the sixth resistor is connected to one end of the capacitor, and the other end of the capacitor is connected to the drain of the PMOS tube.

5. The curvature-corrected bandgap reference circuit according to claim 1, wherein: The low-temperature curvature correction module further includes an eleventh resistor, one end of the eleventh resistor is connected to the base of the first NPN transistor, and the other end of the eleventh resistor is connected to the emitter of the first NPN transistor.

6. The curvature-corrected bandgap reference circuit according to claim 1, wherein: The size of the fifth NPN transistor is greater than that of the fourth NPN transistor.

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