Band-gap reference circuit for subrange piecewise linear compensation and control method
By using a sub-range segmented linear compensation bandgap reference circuit, and utilizing positive and negative temperature coefficient currents and digital-to-analog converters for temperature segmentation, the problem of high-order temperature coefficients in traditional bandgap reference circuits over a wide temperature range is solved, achieving a high-precision and low-power circuit design.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG INST OF BUSINESS & TECH
- Filing Date
- 2026-01-23
- Publication Date
- 2026-04-21
AI Technical Summary
Traditional bandgap reference circuits are susceptible to the influence of high-order temperature coefficients on the output reference voltage over a wide temperature range, resulting in degraded circuit performance and difficulty in meeting the requirements of high precision and low power consumption.
A bandgap reference circuit with sub-range segmented linear compensation is adopted. By superimposing positive and negative temperature coefficient currents and combining them with a digital-to-analog converter, a comparator is used to perform temperature segmentation. A PTAT current source and a curvature compensation current generation circuit are introduced to compensate for different temperature ranges.
It effectively suppresses the interference of the second-order temperature coefficient on the output reference voltage, improves temperature stability and circuit robustness, reduces compensation current requirements and chip area, adapts to different process deviations, and provides a reliable high-precision reference voltage.
Smart Images
Figure CN121900570A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor integrated circuit technology, and specifically relates to a bandgap reference circuit and control method with sub-range piecewise linear compensation. Background Technology
[0002] In the field of integrated circuit design, bandgap reference circuits are fundamental and critical circuit units typically used to generate reference voltages, and are widely used in analog, digital, and mixed-signal circuit systems. Typical applications include analog-to-digital converters (ADCs), digital-to-analog converters (DACs), power management modules, and sensor front-end circuits. Bandgap reference voltage sources are generally used to generate a stable reference voltage that is insensitive to temperature, power supply voltage, and manufacturing process fluctuations. With the continuous evolution of semiconductor manufacturing processes and the increasing diversification of end-application requirements, higher demands are being placed on bandgap reference voltage sources in terms of accuracy, power consumption, and chip area.
[0003] Due to the operating environment requirements of circuit systems, bandgap reference circuits typically operate over a wide temperature range. Traditional bandgap reference circuits usually only perform first-order temperature coefficient compensation. However, because the output voltage reference contains higher-order temperature coefficients, the error introduced by the second-order temperature coefficient gradually increases as the ambient temperature decreases or increases. This causes the reference voltage output by the bandgap reference circuit to deviate from the design value, ultimately leading to a deterioration in the overall performance of the circuit system. To reduce the impact of errors introduced by higher-order terms, higher-order temperature compensation mechanisms are usually introduced at both ends of the operating temperature range to improve the temperature drift performance of the output reference voltage. Due to process limitations, the actual compensation effect often deviates from the initial design. To stabilize the effect of higher-order compensation, higher-order compensation adjustment circuits are added to the initial design to adjust the higher-order temperature compensation to meet the design performance. However, the wide temperature range complicates the adjustment circuits, resulting in higher power consumption and larger area during design and implementation. This is detrimental to achieving circuit miniaturization and low power consumption.
[0004] In voltage reference circuits, the temperature drift coefficient is a crucial parameter for evaluating voltage stability. It reflects the degree of voltage fluctuation in the output voltage as the circuit's operating temperature changes. Traditional first-order compensated bandgap voltage reference sources typically achieve stability of only around 30 ppm / ℃ over a wide temperature range, which is insufficient for more demanding applications. Even with complete first-order temperature coefficient compensation, the presence of the second-order temperature coefficient still significantly impacts the voltage output, especially at extreme temperatures. This makes optimizing the temperature coefficient a significant challenge. Summary of the Invention
[0005] To overcome the problems in the prior art, this invention proposes a bandgap reference circuit with subrange piecewise linear compensation.
[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a bandgap reference circuit with sub-range piecewise linear compensation, including a core circuit and a sub-range linear compensation circuit. The core circuit is used to achieve temperature segmentation by superimposing currents with positive and negative temperature coefficients and combining them with a digital-to-analog converter, and then using a comparator to fine-tune the ratio of positive and negative temperature coefficient currents in different temperature ranges. The sub-range linear compensation circuit includes a PTAT current source circuit and a curvature compensation current generation circuit. The PTAT current source circuit is used to stabilize the current with a positive temperature coefficient, serving as the basic current source for the sub-range linear compensation circuit. The curvature compensation current generation circuit is used to generate compensation current in the high-temperature region and compensation current in the low-temperature region, so as to effectively compensate for the second-order temperature coefficient in different sub-temperature ranges.
[0007] Furthermore, the core circuit includes an amplifier, a first transistor, a second transistor, a first resistor, a second resistor, a digital-to-analog converter, a current mirror unit, an output unit, and a comparator; The current mirror unit has a first terminal, a second terminal, a third terminal, a fourth terminal, and a control terminal. The first terminal of a first transistor is connected to the first terminal of the current mirror unit to generate a first CTAT voltage. The second terminal of the first transistor, the control terminal of the first transistor, the second terminal of the second transistor, and the control terminal of the second transistor are connected to ground. The first terminal of the second transistor is connected to the first terminal of a first resistor. The second terminal of the first resistor is connected to the second terminal of the current mirror unit to generate the first voltage. The first terminal of the second resistor is connected to ground. The second terminal of the second resistor is connected to the third terminal of the current mirror unit to generate a second voltage. The first input terminal of the digital-to-analog converter is connected to the second terminal of the first resistor to receive the first voltage. The second input terminal of the digital-to-analog converter is connected to the second terminal of the second resistor to receive the second voltage. The first input terminal of the amplifier is connected to the first terminal of the first transistor to receive the first CTAT voltage. The second input terminal of the amplifier is connected to the output terminal of the digital-to-analog converter to clamp the voltage at the output terminal of the digital-to-analog converter based on the first CTAT voltage. The output terminal of the amplifier is connected to the control terminal of the current mirror unit. The output unit is connected to the fourth terminal of the current mirror unit to generate an output voltage based on the current on the current mirror unit. The comparator is connected to the second terminal of the first resistor, the second terminal of the second resistor, and the digital-to-analog converter to generate a digital input code for adjusting the digital-to-analog converter based on the first voltage and the second voltage.
[0008] Furthermore, the output unit includes a third resistor, a fourth resistor, and a fifth resistor connected in series.
[0009] Furthermore, the current mirror unit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor are respectively connected to the power supply voltage. The control terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor are connected to the output terminal of the amplifier.
[0010] Furthermore, the PTAT current source circuit includes a thirteenth transistor, a fourteenth transistor, a nineteenth transistor, a twentieth transistor, and a seventh resistor; the first terminals of the thirteenth and fourteenth transistors are respectively connected to the power supply voltage, the first terminal of the nineteenth transistor is connected to the ground voltage, the first terminal of the twentieth transistor is connected to the second terminal of the seventh resistor, and the first terminal of the seventh resistor is connected to the power supply voltage; the second terminal of the thirteenth transistor is connected to the second terminal of the nineteenth transistor, and the control terminal of the thirteenth transistor is connected to the second terminal of the thirteenth transistor; the second terminal of the fourteenth transistor is connected to the second terminal of the twentieth transistor, and the control terminal of the fourteenth transistor is connected to the second terminal of the fourteenth transistor.
[0011] Furthermore, the high-temperature compensation circuit includes a sixth transistor, an eighth transistor, an eleventh transistor, a twelfth transistor, a seventeenth transistor, and an eighteenth transistor; the first terminals of the sixth transistor, the eighth transistor, the eleventh transistor, and the twelfth transistor are respectively connected to the power supply voltage; the first terminals of the seventeenth transistor and the eighteenth transistor are respectively connected to the ground voltage; the second terminal of the eighth transistor is connected to the second terminal of the seventeenth transistor, and the second terminal of the sixth transistor is connected to the second terminal of the eighteenth transistor; the second terminal of the eleventh transistor is connected to the second terminal of the sixth transistor, the control terminal of the sixth transistor is connected to the control terminal of the first transistor, the second terminal of the twelfth transistor is connected to the first terminal of the fourth resistor of the output unit; the control terminal of the seventeenth transistor is connected to the control terminal of the eighteenth transistor, and the control terminal of the seventeenth transistor is connected to the second terminal of the seventeenth transistor; the control terminal of the eleventh transistor is connected to the control terminal of the twelfth transistor, and the control terminal of the eleventh transistor is connected to the second terminal of the eleventh transistor.
[0012] Furthermore, the low-temperature compensation circuit includes a fifth transistor, a seventh transistor, a ninth transistor, a tenth transistor, a fifteenth transistor, and a sixteenth transistor; the first terminals of the fifth transistor, the ninth transistor, and the tenth transistor are respectively connected to the power supply voltage, and the first terminals of the fifteenth transistor and the sixteenth transistor are respectively connected to the ground voltage; the second terminal of the fifth transistor is connected to the second terminal of the fifteenth transistor; the second terminal of the seventh transistor is connected to the second terminal of the sixteenth transistor, the control terminal of the fifteenth transistor is connected to the control terminal of the sixteenth transistor, and the control terminal of the fifteenth transistor is connected to the second terminal of the fifteenth transistor; the control terminal of the ninth transistor is connected to the control terminal of the tenth transistor, the second terminal of the ninth transistor is connected to the second terminal of the seventh transistor, the second terminal of the tenth transistor is connected to the first terminal of the third resistor in the output unit, and the control terminal of the fifth transistor is connected to the output terminal of the amplifier; the control terminal of the seventh transistor is connected to the PTAT current source circuit.
[0013] In a second aspect, a control method for a sub-range piecewise linearly compensated bandgap reference circuit is provided, based on the sub-range piecewise linearly compensated bandgap reference circuit described in the first aspect, the control method comprising: A first CTAT voltage is generated at the first terminal of the first transistor; the amplifier clamps the voltage at the output terminal DACout of the digital-to-analog converter based on the voltage value of the first CTAT voltage. The amplifier output signal controls the current mirror unit, which is used to replicate the current, copying the current from the PTAT current source circuit and the core circuit to each branch according to a preset ratio. The comparator simultaneously receives a first voltage and a second voltage, compares and analyzes the voltages, and generates a digital input code to adjust the digital-to-analog converter based on the comparison result. The digital input code will be used to adjust the ratio of the internal resistance of the digital-to-analog converter. In high-temperature environments, the high-temperature compensation circuit starts working, proportionally replicating the current generated by the core circuit and combining it with the current generated by the PTAT current source to generate a high-temperature compensation current. In low-temperature environments, the low-temperature compensation circuit starts working, proportionally replicating the current generated by the core circuit and combining it with the current generated by the PTAT current source to generate a low-temperature compensation current. The output unit generates the final output voltage based on the current distributed by the current mirror unit and the current after adjustment by the high-temperature compensation circuit and the low-temperature compensation circuit.
[0014] Furthermore, in a high-temperature environment, the second terminal of the twelfth transistor is connected to the first terminal of the fourth resistor of the output unit, and the resulting differential current compensates for the output voltage.
[0015] Furthermore, in a low-temperature environment, the second terminal of the tenth transistor is connected to the first terminal of the third resistor in the output unit, and the resulting differential current compensates for the output voltage.
[0016] Compared with the prior art, the present invention has the following technical effects: (1) The core circuit designed in this invention achieves temperature segmentation by superimposing currents with positive and negative temperature coefficients and introducing a digital-to-analog converter (DAC). A comparator is used to fine-tune the ratio of positive and negative temperature coefficient currents within different temperature ranges. Based on this, a sub-range linear circuit is introduced within each temperature sub-range, which effectively suppresses the interference of the second-order temperature coefficient on the output reference voltage and improves temperature stability. Moreover, the linear compensation method within the sub-range has significant advantages, reducing the required compensation current and correspondingly decreasing the chip area. This improves performance while also meeting the requirements of miniaturization design, providing strong support for the high integration development of integrated circuits.
[0017] (2) After completing the sub-temperature band compensation, to further eliminate the residual effect of the first-order temperature coefficient, this invention uses a DAC to adjust the first-order temperature coefficient. The DAC can calibrate the first-order temperature coefficient according to the actual process deviation, making the output voltage more stable. Through this adjustment, the circuit's sensitivity to process deviations is greatly reduced, and its robustness is significantly enhanced. Whether in chips produced in different batches or facing complex and ever-changing external environments, this bandgap reference circuit can maintain excellent performance, providing a reliable high-precision reference voltage for integrated circuit systems. Attached Figure Description
[0018] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This invention provides a bandgap reference circuit with sub-range linear compensation. Figure 2 The basic principle for achieving linear compensation of temperature segments and sub-ranges; Figure 3 This is a scan diagram of the output voltage within the operating range of this invention; Figure 4 This is a power supply suppression diagram of the present invention. Detailed Implementation
[0020] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the specific implementation methods, structures, features, and effects of the technical solutions proposed according to the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments. Specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0021] This invention provides a sub-range piecewise linear compensation bandgap reference circuit and control method, aiming to solve the problem that the output reference voltage is easily affected by high-order temperature coefficients in the prior art, thereby significantly reducing the temperature drift coefficient over the entire operating temperature range.
[0022] The core circuit of this invention achieves temperature segmentation by superimposing currents with positive and negative temperature coefficients and combining them with a digital-to-analog converter (DAC). A comparator finely adjusts the ratio of positive and negative temperature coefficient currents within different temperature ranges. Furthermore, a sub-range linear circuit is introduced within each temperature sub-range to effectively suppress the influence of the second-order temperature coefficient on the output reference voltage, thereby improving temperature stability. Moreover, because linear compensation is performed within a sub-range, the required compensation current and the occupied area are reduced.
[0023] In this bandgap reference circuit, all MOS transistors used are standard CMOS devices and operate in the saturation region, ensuring the stability and consistency of circuit operation. Furthermore, to further eliminate the residual effects of the first-order temperature coefficient after sub-temperature compensation, this invention employs a DAC to achieve precise first-order temperature coefficient adjustment, improving the circuit's robustness to process variations.
[0024] In one embodiment of the present invention, a bandgap reference circuit with sub-range piecewise linear compensation includes a core circuit and a sub-range linear compensation circuit. The core circuit is used to achieve temperature segmentation by superimposing currents with positive and negative temperature coefficients and combining them with a digital-to-analog converter, and then using a comparator to fine-tune the ratio of positive and negative temperature coefficient currents in different temperature ranges. The sub-range linear compensation circuit includes a PTAT current source circuit and a curvature compensation current generation circuit. The PTAT current source circuit is used to stabilize the current with a positive temperature coefficient, serving as the basic current source for the sub-range linear compensation circuit. The curvature compensation current generation circuit is used to generate compensation current in the high-temperature region and compensation current in the low-temperature region, so as to effectively compensate for the second-order temperature coefficient in different sub-temperature ranges.
[0025] In this embodiment, the core circuit includes an amplifier, a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2, a digital-to-analog converter, a current mirror unit, an output unit, and a comparator.
[0026] The current mirror unit has a first terminal, a second terminal, a third terminal, a fourth terminal, and a control terminal. The first terminal of the first transistor Q1 is connected to the first terminal of the current mirror unit to generate a first CTAT voltage V. BE1 The second terminal of the first transistor Q1, the control terminal of the first transistor Q1, the second terminal of the second transistor Q2, and the control terminal of the second transistor Q2 are connected to ground. The first terminal of the second transistor Q2 is connected to the first terminal of the first resistor R1. The second terminal of the first resistor R1 is connected to the second terminal of the current mirror unit to generate a first voltage V1. The first terminal of the second resistor R2 is connected to ground. The second terminal of the second resistor R2 is connected to the third terminal of the current mirror unit to generate a second voltage V2. The first input terminal of the digital-to-analog converter is connected to the second terminal of the first resistor R1 to receive the first voltage V1. The second input terminal of the digital-to-analog converter is connected to the second terminal of the second resistor R2 to receive the second voltage V2. The first input terminal Vin1 of the amplifier is connected to the first terminal of the first transistor Q1 to receive the first CTAT voltage VBE1. The second input terminal Vin2 of the amplifier is connected to the output terminal DACout of the digital-to-analog converter to clamp the voltage at the output terminal DACout of the digital-to-analog converter based on the first CTAT voltage VBE1. The amplifier's output terminal is connected to the control terminal of the current mirror unit, and the output unit is connected to the fourth terminal of the current mirror unit to generate an output voltage V based on the current in the current mirror unit. out The output unit includes a third resistor R3, a fourth resistor R4, and a fifth resistor R5 connected in series. A comparator is connected to the second terminal of the first resistor R1, the second terminal of the second resistor R2, and the digital-to-analog converter to generate a digital input code that adjusts the digital-to-analog converter based on a first voltage V1 and a second voltage V2.
[0027] The current mirror unit includes a first transistor M1, a second transistor M2, a third transistor M3, and a fourth transistor M4. The first terminals of the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are respectively connected to the power supply voltage V. DD The control terminals of the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are connected to the output terminal of the amplifier and are used as the control terminals of the current mirror unit.
[0028] The second terminal of the first transistor M1 is connected to the first terminal of the first transistor Q1, serving as the first terminal of the current mirror unit. The second terminal of the second transistor M2 is connected to the second terminal of the first resistor R1, serving as the second terminal of the current mirror unit. The second terminal of the third transistor M3 is connected to the second terminal of the second resistor R2, serving as the third terminal of the current mirror unit. The second terminal of the fourth transistor M4 is connected to the second terminal of the third resistor R3. The first terminal of the third resistor R3 is connected to the second terminal of the fourth resistor R4. The first terminal of the third resistor R4 is connected to the first terminal of the fifth resistor R5. The first terminal of the fifth resistor R5 is grounded, serving as the fourth terminal of the current mirror unit.
[0029] In a specific embodiment, the first transistor Q1 and the second transistor Q2 are PNP transistors. The first terminal of the first transistor Q1 and the first terminal of the second transistor Q2 are the emitters, and the second terminals of the first transistor Q1 and the second terminals of the second transistor Q2 are the collectors. The control terminals of the first transistor Q1 and the second transistor Q2 are the bases. The first terminal of the transistor is the source, the second terminal is the drain, and the control terminal is the gate. The first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are NMOS transistors. The width-to-length ratios of the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are the same, meaning that the current flowing from the first, second, third, and fourth terminals of the current mirror unit is the same. For ease of description, this current will be referred to as the reference current Iref in the following text. The width-to-length ratios of the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 can also be different, and can be adjusted according to actual needs.
[0030] In this embodiment, the sub-range linear compensation circuit includes a PTAT current source circuit and a curvature compensation current generation circuit. The PTAT current source circuit is used to stabilize the current with a positive temperature coefficient as the basic current source of the sub-range linear compensation circuit. The curvature compensation current generation circuit is used to generate compensation current in the high-temperature region and compensation current in the low-temperature region to effectively compensate for the second-order temperature coefficient in different sub-temperature ranges.
[0031] The PTAT current source circuit includes a thirteenth transistor M13, a fourteenth transistor M14, a nineteenth transistor M19, a twentieth transistor M20, and a seventh resistor Rs. The first terminal of the thirteenth transistor M13 and the first terminal of the fourteenth transistor M14 are connected to the power supply voltage V. DDThe transistors are connected to provide the voltage required for operation. The second terminal of the thirteenth transistor M13 is connected to the second terminal of the nineteenth transistor M19, and the first terminal of the nineteenth transistor M19 is connected to ground. The second terminal of the fourteenth transistor M14 is connected to the second terminal of the twentieth transistor M20, and the first terminal of the twentieth transistor M20 is connected to the second terminal of the seventh resistor Rs, which is connected to ground. The control terminal of the fourteenth transistor M14 is connected to the second terminal of the fourteenth transistor M14. This connection method can stabilize the gate-source voltage Vgs of the fourteenth transistor M14, thereby stabilizing its operating state. The control terminal of the thirteenth transistor M13 is connected to the control terminal of the fourteenth transistor M14 and is connected to the low-temperature compensation circuit to ensure that the thirteenth transistor M13 and the fourteenth transistor M14 have the same gate voltage.
[0032] The thirteenth transistor M13 and the fourteenth transistor M14 are PMOS transistors, while the nineteenth transistor M19 and the twentieth transistor M20 are NMOS transistors. The PTAT current source circuit generates a stable positive temperature coefficient current. Utilizing the conduction characteristics of the PMOS transistors (thirteenth transistor M13 and fourteenth transistor M14), the diode connection of the fourteenth transistor M14 stabilizes its gate-source voltage Vgs, providing a base current reference for the circuit; the gates of M13 and M14 are connected to achieve current matching. The NMOS transistors (nineteenth transistor M19 and twentieth transistor M20) and the seventh resistor Rs form a complete current loop. The seventh resistor Rs affects the current through voltage division and current limiting, thereby adjusting the output current magnitude and temperature coefficient of the entire current source, providing a basis for subsequent compensation.
[0033] In this embodiment, the curvature compensation current generation circuit is divided into a high-temperature compensation circuit and a low-temperature compensation circuit according to the temperature range. They are used to generate INL (high-temperature compensation current) and IPL (low-temperature compensation current) respectively, so as to effectively compensate for the second-order temperature coefficient in different sub-temperature ranges.
[0034] The high-temperature compensation circuit includes transistors M6 (sixth), M8 (eighth), M11 (eleventh), M12 (twelfth), M17 (seventeenth), and M18 (eighteenth). The first terminals of transistors M6, M8, M11, and M12 are respectively connected to the power supply voltage V. DDThe transistors are connected as follows: the first terminal of the seventeenth transistor M17 and the first terminal of the eighteenth transistor M18 are connected to ground; the second terminal of the eighth transistor M8 is connected to the second terminal of the seventeenth transistor M17, and the second terminal of the sixth transistor M6 is connected to the second terminal of the eighteenth transistor M18; the second terminal of the eleventh transistor M11 is connected to the second terminal of the sixth transistor M6, and the control terminal of the sixth transistor M6 is connected to the control terminal of the first transistor M1; the second terminal of the twelfth transistor M12 is connected to the first terminal of the fourth resistor R4 in the output unit; the control terminal of the seventeenth transistor M17 is connected to the control terminal of the eighteenth transistor M18, and the control terminal of the seventeenth transistor M17 is connected to the second terminal of the seventeenth transistor M17; the control terminal of the eleventh transistor M11 is connected to the control terminal of the twelfth transistor M12, and the control terminal of the eleventh transistor M11 is connected to the second terminal of the eleventh transistor M11. Among these, the sixth transistor M6, the eighth transistor M8, the eleventh transistor M11, and the twelfth transistor M12 are NMOS transistors, and the seventeenth transistor M17 and the eighteenth transistor M18 are PMOS transistors.
[0035] As the temperature rises and enters the high-temperature range, the current flowing through the thirteenth transistor M13 and the fourteenth transistor M14 of the PTAT current source increases. This current is replicated to the seventh transistor M7 and the second transistor M8 through the current mirror. The current flowing through the M8 branch is then replicated to the M18 branch through the seventeenth transistor M17 and the eighteenth transistor M18. The sixth transistor M6 replicates the current flowing through the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4. In the high-temperature range, when the current in the sixth transistor M6 is less than the current flowing through the eighteenth transistor M18, the eleventh transistor M11 and the twelfth transistor M12 generate a compensation current, which is injected into the third resistor R3 to form compensation.
[0036] The low-temperature compensation circuit includes transistors M5 (fifth), M7 (seventh), M9 (ninth), M10 (tenth), M15 (fifteenth), and M16 (sixteenth); the first terminals of transistors M5, M9, and M10 are respectively connected to the power supply voltage V. DDThe first terminals of the fifteenth transistor M15 and the sixteenth transistor M16 are connected to ground, forming the reference potential of the current loop. The second terminal of the fifth transistor M5 is connected to the second terminal of the fifteenth transistor M15, forming part of the current path; the second terminal of the seventh transistor M7 is connected to the second terminal of the sixteenth transistor M16; the control terminal of the fifteenth transistor M15 is connected to the control terminal of the sixteenth transistor M16; the control terminal of the fifteenth transistor M15 is connected to the second terminal of the fifteenth transistor M15; the control terminal of the ninth transistor M9 is connected to the control terminal of the tenth transistor M10; the second terminal of the ninth transistor M9 is connected to the second terminal of the seventh transistor M7; the second terminal of the tenth transistor M10 is connected to the first terminal of the third resistor R3 in the output unit; the control terminal of the fifth transistor M5 is connected to the output terminal of the amplifier; the control terminal of the seventh transistor M7 is connected to the PTAT current source circuit.
[0037] As the temperature decreases and enters the lower temperature range, the current flowing through the thirteenth transistor M13 and the fourteenth transistor M14 of the PTAT current source decreases. This current is replicated to the seventh transistor M7 and the fourth transistor M8 through the current mirror. The current flowing through the M7 branch is replicated to the M15 branch through the fifteenth transistor M15 and the sixteenth transistor M16. The fifth transistor M5 replicates the current flowing through the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4. In the lower temperature range, when the current of the fifth transistor M6 is greater than the current flowing through the fifteenth transistor M15, the ninth transistor M9 and the tenth transistor M10 will generate a compensation current, which is injected into the third resistor R3 to form compensation.
[0038] The present invention also provides a control method based on the above-described bandgap reference circuit, the control method comprising: Step 1: Generating the base voltage: When the first transistor Q1 is working normally, the first CTAT voltage V is generated through the first terminal of the first transistor Q1. BE1 .
[0039] Step 2: Voltage clamping and digital code adjustment: The amplifier is based on the first CTAT voltage V BE1 The voltage value is used to clamp the voltage at the output terminal DACout of the digital-to-analog converter; the comparator simultaneously receives the first voltage V1 and the second voltage V2, compares and analyzes the voltages, and generates a digital input code to adjust the digital-to-analog converter based on the comparison result. The digital input code will be used to adjust the ratio of the internal resistance of the digital-to-analog converter.
[0040] Step 3: Current Distribution The amplifier output signal controls the current mirror unit, which replicates the current, copying the current from the PTAT current source circuit and the core circuit to each branch according to a preset ratio. Specifically, the control signal output by the amplifier adjusts the conduction state of the transistors in the current mirror unit, thereby achieving current distribution. The distributed current provides a stable and on-demand current for different parts such as the branches generating V1 and V2, the output unit, and the curvature compensation current generation circuit, ensuring the normal operation of each circuit.
[0041] Step 4: Function of the curvature compensation current generation circuit: High temperature compensation can be set to the middle value of the high temperature sub-range as the starting point of high temperature compensation, 61℃-140℃, take about 100℃.
[0042] As the temperature rises and enters the high-temperature range, the current flowing through the thirteenth transistor M13 and the fourteenth transistor M14 of the PTAT current source increases. This current is replicated to the seventh transistor M7 and the second transistor M8 through the current mirror. The current flowing through the M8 branch is then replicated to the M18 branch through the seventeenth transistor M17 and the eighteenth transistor M18. The sixth transistor M6 replicates the current flowing through the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4. In the high-temperature range, when the current in the sixth transistor M6 is less than the current flowing through the eighteenth transistor M18, the eleventh transistor M11 and the twelfth transistor M12 generate a compensation current, which is injected into the third resistor R3 to form high-temperature compensation.
[0043] Low temperature compensation can be set to the middle value of the low temperature sub-range as the starting point of low temperature compensation, with approximately 10℃ for -40℃ to 61℃.
[0044] As the temperature decreases and enters the low-temperature range, the current flowing through the thirteenth transistor M13 and the fourteenth transistor M14 of the PTAT current source decreases. This current is replicated to the seventh transistor M7 and the fourth transistor M8 through the current mirror. The current flowing through the M7 branch is replicated to the M15 branch through the fifteenth transistor M15 and the sixteenth transistor M16. The fifth transistor M5 replicates the current flowing through the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4. In the low-temperature range, when the current of the fifth transistor M6 is greater than the current flowing through the fifteenth transistor M15, the ninth transistor M9 and the tenth transistor M10 will generate a compensation current, which is injected into the third resistor R3 to form low-temperature compensation.
[0045] Step 5: Output voltage generation: The output unit generates the final output voltage Vout through the voltage division effect of the output unit, based on the current distributed by the current mirror unit and the current after adjustment by the high temperature compensation circuit and the low temperature compensation circuit.
[0046] Combination Figure 1 As shown, the emitter and base IV characteristics of a bipolar junction transistor (BJT) are as follows: ; ; in, It is the collector current. Let b be the saturation current, and m be the proportionality constant. -1.5 is an empirical coefficient. This represents the band gap energy of silicon. Represents thermal voltage; T represents absolute temperature; The voltage difference between the emitter and base : ; By the voltage difference between the emitter and base Find the partial derivative: ; In the above formula, q It represents the amount of electron charge.
[0047] It can be seen that the voltage difference between the emitter and the base is... The relationship with temperature is non-linear, and A voltage with a negative temperature coefficient is called a negative temperature coefficient voltage (CTAT).
[0048] If the current flowing through two different BJT transistors is the same, then the difference between their base-emitter voltages is a voltage proportional to temperature. Assuming the emitter junction area ratio of Q1 and Q2 is 1:N, then: ; As can be seen from the formula, It is a voltage that is proportional to temperature, and this voltage is called a positive temperature coefficient voltage (PTAT); I0 represents the current flowing through two different BJT transistors.
[0049] The voltage difference between the emitter and base of a bipolar junction transistor (BJT) The sum of the voltage differences between the emitter and base of two different BJTs, with a negative temperature coefficient. To achieve a positive temperature coefficient, the operational amplifier's clamping effect generates PTAT and CTAT currents in the circuit. A DAC is inserted at nodes V1 and V2 to segment the temperature coefficient. The principle is to fine-tune the DAC to generate different code values within the two temperature segments. When the ambient temperature changes to the temperature segmentation point, the comparator switches the input code value of the DAC to achieve fine-tuning.
[0050] Reference Figure 2 To achieve a range, the denominator is changed, meaning there are two resistances that vary with the coefficient. changing as well as The formula then becomes: ; In the above formula, Indicates positive temperature coefficient voltage; Indicates a negative temperature coefficient voltage; The first resistance represents the resistance that varies with temperature T. The second resistance represents the resistance that varies with temperature T.
[0051] when = The time, i.e., the time at the temperature breakpoint, is obtained as follows: ; In the above formula, Indicates the temperature breakpoint.
[0052] At this time, the coefficient No longer affecting That is, in all the different coefficients They will all pass through = This temperature point. Utilizing this characteristic, to... Using temperature segmentation points, compensation is applied to the first-order temperature coefficient within each of the two segments to reduce the temperature drift coefficient across the entire temperature range. Based on the two-point calibration method, it can be seen that if the coefficient is adjusted... When the temperatures at both ends are equal, theoretically the first-order temperature coefficient is completely eliminated. Both ends are calibrated at two points, and since both have undergone… This is the temperature segmentation point, where the maximum temperature drift in one sub-range is averaged across the entire temperature range, which significantly reduces the final temperature drift coefficient.
[0053] To achieve the above-described invention, operational amplifier A1, BJT transistors Q1 and Q2, PMOS transistors M1, M2, and M3, resistors R1 and R2, and a segmented DAC are used. This enables temperature segmentation and accurate calibration of the first-order temperature coefficient. A segmented DAC with a total resistance much larger than the second resistor R2 is inserted between the first resistor R1 and the second resistor R2, making the current flowing through it almost zero. The temperature range segmentation is achieved by using the comparator value to determine the fine-tuning resistor.
[0054] The PTAT current source circuit adopts a self-biased structure, consisting of four MOSFETs and one resistor. It generates a current with a stable positive temperature coefficient, serving as the base current source for subsequent compensation circuits. Its working principle is as follows: The thirteenth transistor M13 and the fourteenth transistor M14 are two PMOS current mirrors, with almost identical currents flowing through them; the nineteenth transistor M19 and the twentieth transistor M20 are NMOS transistors, operating in the saturation region with a ratio of K:1. The gate-source voltage relationship between the two MOSFETs can be expressed as: ; In the above formula, This represents the gate-source voltage of M19; This represents the gate-source voltage of M20.
[0055] Due to the drain current of the MOSFET operating in the saturation region It can be represented as: ; The above formula, This represents the capacitance of the gate oxide layer per unit area. Indicates the width-to-length ratio of a MOS transistor; This represents the threshold voltage.
[0056] Substituting the values, we get the following formula: ; Assume the influence of the deception effect and simplify it: ; ; Due to electron mobility The current decreases as temperature increases, therefore the current increases as temperature increases, and the circuit generates a PTAT current source.
[0057] The curvature compensation current generation circuit is divided into a high-temperature compensation circuit and a low-temperature compensation circuit according to the temperature range. These circuits generate INL (high-temperature compensation current) and IPL (low-temperature compensation current) respectively, to effectively compensate for the second-order temperature coefficient within different sub-temperature ranges. The compensation current is generated by proportionally replicating the current generated by the core circuit and combining it with the current generated by the PTAT current source. When the temperature is too high or too low, the difference between the two currents flows back to the output segment in a certain proportion to compensate for the output voltage, thereby reducing the tendency of the output voltage to change with temperature.
[0058] Figure 3 This is the voltage-temperature characteristic curve based on sub-range linear compensation. The approximate midpoint (61℃) of the full temperature range from -40℃ to 140℃ is selected as the segmentation threshold. This threshold is directly related to the resistance ratio of the first and second resistors. Using this as the boundary, the entire temperature range is divided into a low-temperature sub-range and a high-temperature sub-range. The curvature compensation circuit can perform compensation operations in each of the two sub-ranges, ultimately achieving a second-order temperature coefficient compensation effect. This compensation effect can be visually observed from the concave shape of the curve in the figure. Figure 4 This displays the power supply rejection of the reference voltage source, which is designed to suppress low-frequency power supply fluctuations by -60dB.
[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A bandgap reference circuit with sub-range piecewise linear compensation, characterized in that, Includes the core circuit and sub-range linear compensation circuit; The core circuit is used to achieve temperature segmentation by superimposing currents with positive and negative temperature coefficients and combining them with a digital-to-analog converter, and then using a comparator to fine-tune the ratio of positive and negative temperature coefficient currents in different temperature ranges. The sub-range linear compensation circuit includes a PTAT current source circuit and a curvature compensation current generation circuit. The PTAT current source circuit is used to stabilize the current with a positive temperature coefficient, serving as the basic current source for the sub-range linear compensation circuit. The curvature compensation current generation circuit is used to generate compensation current in the high-temperature region and compensation current in the low-temperature region, so as to effectively compensate for the second-order temperature coefficient in different sub-temperature ranges.
2. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 1, characterized in that, The core circuit includes an amplifier, a first transistor, a second transistor, a first resistor, a second resistor, a digital-to-analog converter, a current mirror unit, an output unit, and a comparator; The current mirror unit has a first terminal, a second terminal, a third terminal, a fourth terminal, and a control terminal. The first terminal of a first transistor is connected to the first terminal of the current mirror unit to generate a first CTAT voltage. The second terminal of the first transistor, the control terminal of the first transistor, the second terminal of the second transistor, and the control terminal of the second transistor are connected to ground. The first terminal of the second transistor is connected to the first terminal of a first resistor. The second terminal of the first resistor is connected to the second terminal of the current mirror unit to generate the first voltage. The first terminal of the second resistor is connected to ground. The second terminal of the second resistor is connected to the third terminal of the current mirror unit to generate a second voltage. The first input terminal of the digital-to-analog converter (DAC) is connected to the second terminal of the first resistor to receive the first voltage. The second input terminal of the DAC is connected to the second terminal of the second resistor to receive the second voltage. The first input terminal of the amplifier is connected to the first terminal of the first transistor to receive the first CTAT voltage. The second input terminal of the amplifier is connected to the output terminal of the DAC to clamp the voltage at the output terminal of the DAC based on the first CTAT voltage. The output terminal of the amplifier is connected to the control terminal of the current mirror unit. The output unit is connected to the fourth terminal of the current mirror unit to generate an output voltage based on the current in the current mirror unit. The comparator is connected to the second terminal of the first resistor, the second terminal of the second resistor, and the digital-to-analog converter to generate a digital input code that regulates the digital-to-analog converter based on the first voltage and the second voltage.
3. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 2, characterized in that, The output unit includes a third resistor, a fourth resistor, and a fifth resistor connected in series.
4. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 2, characterized in that, The current mirror unit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor are respectively connected to the power supply voltage. The control terminals of the first transistor, the second transistor, the third transistor, and the fourth transistor are connected to the output terminal of the amplifier.
5. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 1, characterized in that, The PTAT current source circuit includes a thirteenth transistor, a fourteenth transistor, a nineteenth transistor, a twentieth transistor, and a seventh resistor. The first terminals of the thirteenth and fourteenth transistors are connected to the power supply voltage, the first terminal of the nineteenth transistor is connected to ground, and the first terminal of the twentieth transistor is connected to the second terminal of the seventh resistor, which is also connected to the power supply voltage. The second terminal of the thirteenth transistor is connected to the second terminal of the nineteenth transistor, and the control terminal of the thirteenth transistor is connected to the second terminal of the thirteenth transistor. The second terminal of the fourteenth transistor is connected to the second terminal of the twentieth transistor, and the control terminal of the fourteenth transistor is connected to the second terminal of the fourteenth transistor.
6. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 1, characterized in that, The high-temperature compensation circuit includes a sixth transistor, an eighth transistor, an eleventh transistor, a twelfth transistor, a seventeenth transistor, and an eighteenth transistor. The first terminals of the sixth, eighth, eleventh, and twelfth transistors are connected to the power supply voltage, respectively. The first terminals of the seventeenth and eighteenth transistors are connected to the ground voltage, respectively. The second terminal of the eighth transistor is connected to the second terminal of the seventeenth transistor, and the second terminal of the sixth transistor is connected to the second terminal of the eighteenth transistor. The second terminal of the eleventh transistor is connected to the second terminal of the sixth transistor. The control terminal of the sixth transistor is connected to the control terminal of the first transistor. The second terminal of the twelfth transistor is connected to the first terminal of the fourth resistor in the output unit. The control terminal of the seventeenth transistor is connected to the control terminal of the eighteenth transistor, and the control terminal of the seventeenth transistor is connected to the second terminal of the seventeenth transistor. The control terminal of the eleventh transistor is connected to the control terminal of the twelfth transistor, and the control terminal of the eleventh transistor is connected to the second terminal of the eleventh transistor.
7. The bandgap reference circuit with sub-range piecewise linear compensation according to claim 1, characterized in that, The low-temperature compensation circuit includes the fifth transistor, the seventh transistor, the ninth transistor, the tenth transistor, the fifteenth transistor, and the sixteenth transistor; The first terminals of the fifth transistor, the ninth transistor, and the tenth transistor are connected to the power supply voltage, respectively; the first terminals of the fifteenth transistor and the sixteenth transistor are connected to the ground voltage, respectively; the second terminal of the fifth transistor is connected to the second terminal of the fifteenth transistor; the second terminal of the seventh transistor is connected to the second terminal of the sixteenth transistor; the control terminal of the fifteenth transistor is connected to the control terminal of the sixteenth transistor; the control terminal of the fifteenth transistor is connected to the second terminal of the fifteenth transistor; the control terminal of the ninth transistor is connected to the control terminal of the tenth transistor; the second terminal of the ninth transistor is connected to the second terminal of the seventh transistor; the second terminal of the tenth transistor is connected to the first terminal of the third resistor in the output unit; the control terminal of the fifth transistor is connected to the output terminal of the amplifier; the control terminal of the seventh transistor is connected to the PTAT current source circuit.
8. A control method for a sub-range piecewise linear compensation bandgap reference circuit, characterized in that, Based on the sub-range piecewise linear compensation bandgap reference circuit according to any one of claims 1-7, the control method includes: A first CTAT voltage is generated at the first terminal of the first transistor; the amplifier clamps the voltage at the output terminal DACout of the digital-to-analog converter based on the voltage value of the first CTAT voltage. The amplifier output signal controls the current mirror unit, which is used to replicate the current, copying the current from the PTAT current source circuit and the core circuit to each branch according to a preset ratio. The comparator simultaneously receives a first voltage and a second voltage, compares and analyzes the voltages, and generates a digital input code to adjust the digital-to-analog converter based on the comparison result. The digital input code will be used to adjust the ratio of the internal resistance of the digital-to-analog converter. In high-temperature environments, the high-temperature compensation circuit starts working, proportionally replicating the current generated by the core circuit and combining it with the current generated by the PTAT current source to generate a high-temperature compensation current. In low-temperature environments, the low-temperature compensation circuit starts working, proportionally replicating the current generated by the core circuit and combining it with the current generated by the PTAT current source to generate a low-temperature compensation current. The output unit generates the final output voltage based on the current distributed by the current mirror unit and the current after adjustment by the high-temperature compensation circuit and the low-temperature compensation circuit.
9. The control method for a sub-range piecewise linear compensation bandgap reference circuit according to claim 8, characterized in that, In a high-temperature environment, the second terminal of the twelfth transistor is connected to the first terminal of the fourth resistor of the output unit, and the resulting differential current compensates for the output voltage.
10. The control method for a sub-range piecewise linear compensation bandgap reference circuit according to claim 8, characterized in that, In low-temperature environments, the second terminal of the tenth transistor is connected to the first terminal of the third resistor in the output unit, and the resulting differential current compensates for the output voltage.