A bandgap reference current source, a low dropout linear regulator and a power manager

Abstract

This application provides a bandgap reference current source, a low-dropout linear regulator, and a power manager, which are applied in the field of power chip technology. The bandgap reference current source uses dual bandgap references to form a bandgap reference loop and uses an operational amplifier clamping unit to achieve clamping adjustment, thereby generating a reference current proportional to temperature. This facilitates subsequent linear regulation using the reference current, giving the regulator high load capacity, very low quiescent current, and high power supply noise rejection ratio, which can improve the overall efficiency of the voltage regulator circuit and greatly reduce the layout area.

Description

Technical Field

[0001] This application relates to the field of power chip technology, specifically to a bandgap reference current source, a low dropout linear regulator, and a power manager. Background Technology

[0002] The main functional circuit units of an existing low dropout linear regulator (LDO) include: a reference source, an error amplifier, a feedback resistor network, protection circuits, an enable circuit, and a bias power supply. Among these, the MOSFET-type LDO primarily utilizes the constant current region of the MOSFET to adjust V... GS Voltage is used to control the output current and stabilize the output voltage of a MOSFET by placing it in different current states. However, under the existing structure and voltage regulation principle, the output voltage of an LDO is easily affected.

[0003] Therefore, the structure and circuit performance of LDOs need to be improved and enhanced. Summary of the Invention

[0004] In view of this, the embodiments of this specification provide a bandgap reference current source, a low dropout linear regulator, and a power manager, forming a novel reference current source in the LDO structure. This source can provide a reference current proportional to temperature, which helps to reduce the influence of the internal functional circuit of the LDO on the output voltage. It also has a high power supply rejection ratio, high load capacity, and helps to improve the overall circuit performance of the LDO.

[0005] The embodiments in this specification provide the following technical solutions:

[0006] This specification provides a bandgap reference current source, including: a first bandgap reference circuit, a second bandgap reference circuit, and an operational amplifier clamping circuit; the first bandgap reference circuit includes a first resistor, a first MOSFET, a second MOSFET, and a first transistor; the second bandgap reference circuit includes a second resistor, a third MOSFET, a fourth MOSFET, a second transistor, and a third resistor; the operational amplifier clamping circuit includes an operational amplifier circuit;

[0007] In this circuit, one end of the first resistor is connected to the input power supply, and the other end is connected to the source of the first MOSFET. The gate of the first MOSFET is connected to the gate of the third MOSFET, the drain of the first MOSFET, and the first differential input terminal of the operational amplifier circuit. The drain of the first MOSFET is connected to the drain of the second MOSFET. The gate of the second MOSFET is connected to the gate of the fourth MOSFET, the base of the first transistor, and the base of the second transistor. The source of the second MOSFET is connected to the collector of the first transistor. The emitter of the first transistor is connected to the power supply ground. One end of the second resistor is connected to the input power supply, and the other end is connected to the source of the third MOSFET. The drain of the third MOSFET is connected to the second differential input terminal of the operational amplifier circuit and the drain of the fourth MOSFET. The source of the fourth MOSFET is connected to the collector of the second transistor. The emitter of the second transistor is connected to the power supply ground through the third resistor. The output terminal of the operational amplifier circuit is connected to the source of the first MOSFET and the source of the third MOSFET. The base of the first transistor serves as the output terminal of a constant current source to provide an output current proportional to temperature.

[0008] Preferably, the operational amplifier circuit includes a fifth MOSFET, a sixth MOSFET, a seventh MOSFET, an eighth MOSFET, and a ninth MOSFET;

[0009] The source of the fifth MOSFET is connected to the input power supply, and the drain of the fifth MOSFET is connected to the source of the sixth MOSFET and the source of the seventh MOSFET. The gate of the sixth MOSFET serves as the first differential input terminal of the operational amplifier circuit. The gate of the seventh MOSFET serves as the second differential input terminal of the operational amplifier circuit. The eighth and ninth MOSFETs form a current mirror, with the drain of the eighth MOSFET connected to the drain of the sixth MOSFET, the gate of the eighth MOSFET, and the gate of the ninth MOSFET. The drain of the ninth MOSFET is connected to the drain of the seventh MOSFET. The sources of the eighth and ninth MOSFETs are connected to the power supply ground. The drain of the ninth MOSFET serves as the output terminal of the operational amplifier circuit.

[0010] The gate of the fifth MOSFET is used for power-on control so that the fifth MOSFET is turned on after the input power is applied to form the quiescent current of the operational amplifier circuit.

[0011] Preferably, the operational amplifier circuit further includes a tenth MOSFET and an eleventh MOSFET. The gates of the tenth MOSFET and the eleventh MOSFET are connected to the drain of the ninth MOSFET, and the sources of the tenth MOSFET and the eleventh MOSFET are connected to the power supply ground. The drain of the tenth MOSFET serves as the first output terminal of the operational amplifier circuit and is connected to the source of the first MOSFET. The drain of the eleventh MOSFET serves as the second output terminal of the operational amplifier circuit and is connected to the source of the third MOSFET.

[0012] Preferably, the bandgap reference current source further includes a startup circuit, which includes a fourth resistor and a twelfth MOS transistor. The drain of the twelfth MOS transistor is connected to the gate of the first MOS transistor and the drain of the fourth MOS transistor. The gate of the twelfth MOS transistor is connected to the power supply ground, and the source of the twelfth MOS transistor is connected to the power supply ground through the fourth resistor. The twelfth MOS transistor is a depletion-type MOS transistor.

[0013] Preferably, the startup circuit further includes a fifth resistor and a thirteenth MOSFET. One end of the fifth resistor is connected to the input power supply, and the other end of the fifth resistor is connected to the source of the thirteenth MOSFET. The drain of the thirteenth MOSFET is connected to the source of the twelfth MOSFET, and the gate of the thirteenth MOSFET is connected to the drain of the first MOSFET.

[0014] Preferably, the startup circuit further includes a fourteenth MOS transistor, the drain of which is connected to the source of the thirteenth MOS transistor, the source of which is connected to the power supply ground, and the gate of which is connected to the output terminal of the operational amplifier circuit.

[0015] Preferably, the second and fourth MOSFETs are depletion-mode MOSFETs;

[0016] And / or, the resistance values ​​of the first resistor and the second resistor are equal;

[0017] And / or, the first MOSFET and the third MOSFET are a matched pair;

[0018] And / or, the second MOSFET and the fourth MOSFET are a matched pair.

[0019] This specification also provides an embodiment of a low-dropout linear regulator, comprising:

[0020] Bandgap reference current source as described in any of the items in this specification;

[0021] Power MOSFET;

[0022] The adjustment circuit includes a third transistor and a sixth resistor.

[0023] In this configuration, the output terminal of the bandgap reference current source is connected to the base of the third transistor, the emitter of the third transistor is connected to the power supply ground, the collector of the third transistor is connected to the base of the third transistor and one end of the sixth resistor, the other end of the sixth resistor is connected to the drain of the power MOSFET, the source of the power MOSFET is connected to the input power supply, the drain of the power MOSFET serves as the output terminal of the voltage regulator, and the gate of the power MOSFET is used for power-on control so that the power MOSFET is turned on after the input power supply is powered on, so as to provide an output voltage to the outside through the output terminal of the voltage regulator.

[0024] Preferably, the low-dropout linear regulator further includes a filter capacitor and / or a Miller capacitor, wherein the filter capacitor is connected between the drain of the power MOSFET and the power supply ground for output filtering of the regulator; the Miller capacitor is connected between the gate and drain of the power MOSFET for power MOSFET.

[0025] This specification also provides a power manager, including: a bandgap reference current source as described in any one of the present specification, or a low-dropout linear regulator as described in any one of the present specification; wherein the bandgap reference current source is used to provide an output current proportional to temperature; and the low-dropout linear regulator is used to provide a supply voltage.

[0026] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0027] By proposing a bandgap reference current source to construct the LDO structure based on the traditional LDO circuit, the LDO can generate a temperature-independent reference voltage. Furthermore, by combining the LDO loop with the bandgap reference loop, this invention offers higher load-carrying capacity compared to traditional bandgap reference circuits, and also exhibits significantly lower quiescent current and higher power supply noise suppression ratio, thus improving the overall efficiency of the LDO circuit. In addition, due to the single loop in this bandgap structure, the invention greatly reduces the layout area compared to traditional LDOs. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of a bandgap reference current source and a low dropout linear regulator according to this application;

[0030] Figure 2 This is a schematic diagram showing the influence of base voltage on current in the bandgap reference circuit of this application.

[0031] Among them, 10 is the start-up unit, 20 is the first bandgap reference, 30 is the operational amplifier clamping unit, 40 is the second bandgap reference, and 50 is the output unit. Detailed Implementation

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0033] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0035] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0037] Existing LDOs achieve constant current control by adjusting the VGS voltage to keep the MOSFET in different current states, thus utilizing the MOSFET's constant current region to stabilize the output voltage.

[0038] Due to the inherent limitations of MOS, the above structure and working principle make the output voltage easily affected.

[0039] In view of this, the inventors conducted in-depth research and improvement on the structure and working principle of linear regulators and found that in the existing LDO structure, the current source required for voltage regulation is realized by using the constant current region of the MOSFET, which is easily affected by various factors, such as input voltage, load changes, etc. Moreover, it is difficult to offset or reduce the influence of these factors on the current source through other means, which leads to current fluctuations used for voltage regulation control, and in turn causes fluctuations in the output voltage, affecting the improvement of the LDO circuit performance.

[0040] Based on this, the embodiments in this specification propose a reference current source scheme that can be used for LDOs: such as Figure 1 As shown, in the LDO structure, two bandgap references (i.e., the first bandgap reference and the second bandgap reference) are used to form a new bandgap loop unit, and the bandgap is clamped and adjusted using an operational amplifier. This allows the bandgap reference unit to generate a proportional to the temperature reference current (PTAT), eliminating other possible influences on the current. This facilitates the subsequent use of temperature coefficient-related circuits to perform temperature coefficient compensation on the PTAT reference current to obtain a temperature-independent reference voltage. In other words, the LDO can obtain an output voltage that is not affected by temperature, which greatly improves the temperature coefficient suppression performance of the linear regulator, improves the stability of the regulated output voltage, and enhances the performance of the LDO circuit.

[0041] Furthermore, the bandgap reference type LDO structure of the present invention has only one loop, resulting in a smaller area in the layout.

[0042] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0043] The present invention will now be described in further detail with reference to the accompanying drawings.

[0044] Reference design circuit such as Figure 1 As shown, a bandgap reference current source includes: a first bandgap reference circuit, a second bandgap reference circuit, and an operational amplifier clamping circuit.

[0045] like Figure 1The diagram illustrates that the first bandgap reference circuit includes a first resistor R3, a first MOSFET M2A, a second MOSFET M2C, and a first transistor Q2; the second bandgap reference circuit includes a second resistor R1, a third MOSFET M2B, a fourth MOSFET M2D, a second transistor Q1, and a third resistor R2; the operational amplifier clamping circuit includes an operational amplifier circuit; wherein, one end of the first resistor R3 is connected to the input power supply, and the other end of the first resistor R3 is connected to the source of the first MOSFET M2A; the gate of the first MOSFET M2A is connected to the gate of the third MOSFET M2B, the drain of the first MOSFET M2A, and the first differential input terminal of the operational amplifier circuit; the drain of the first MOSFET M2A is connected to the drain of the second MOSFET M2C; the gate of the second MOSFET M2C is connected to the gate of the fourth MOSFET M2D, the base of the first transistor Q2, and... The base of the second transistor Q1 is connected, and the source of the second MOSFET M2C is connected to the collector of the first transistor Q2. The emitter of the first transistor Q2 is connected to the power supply ground (GND). One end of the second resistor R1 is connected to the input power supply (VIN), and the other end of the second resistor R1 is connected to the source of the third MOSFET M2B. The drain of the third MOSFET M2B is connected to the second differential input terminal of the operational amplifier circuit and the drain of the fourth MOSFET M2D. The source of the fourth MOSFET M2D is connected to the collector of the second transistor Q1. The emitter of the second transistor Q1 is connected to the power supply ground through the third resistor R2. The output terminal of the operational amplifier circuit is connected to the source of the first MOSFET M2A and the source of the third MOSFET M2B. The base of the first transistor Q2 serves as the output terminal of the current source to provide an output current proportional to the temperature.

[0046] In the aforementioned bandgap reference unit, the first bandgap reference and the second bandgap reference each include resistors R1 and R3 with equal resistance values. One end of the resistor is connected to the voltage "VIN", and the other end is connected to the source of current mirrors M2B and M2A, respectively. The drain of current mirrors M2A and M2B is connected to the drain of current mirrors M2C and M2D, respectively.

[0047] Furthermore, transistors M2C and M2D are depletion-type MOSFETs (where Vth is approximately -100mV). The gates of transistors M2C and M2D are connected together with the bases of transistors Q1 and Q2. The sources of transistors M2C and M2D are connected to the collectors of transistors Q2 and Q1, respectively. The emitter of transistor Q2 is connected to the voltage "GND", and the emitter of transistor Q1 is connected to one end of resistor R2, while the other end of resistor R2 is connected to the voltage "GND".

[0048] In some implementations, the operational amplifier circuit can be Figure 1 The illustrated five-tube amplifier circuit can also be other circuit configurations.

[0049] Below is an example of a five-transistor amplifier circuit. Figure 1 The operational amplifier circuit includes a fifth MOSFET M1A, a sixth MOSFET M1B, a seventh MOSFET M1C, an eighth MOSFET M1D, and a ninth MOSFET M1E.

[0050] In this circuit, the source of the fifth MOSFET M1A is connected to the input power supply, and the drain of the fifth MOSFET M1A is connected to the source of the sixth MOSFET M1B and the source of the seventh MOSFET M1C. The gate of the sixth MOSFET M1B serves as the first differential input terminal of the operational amplifier circuit. The gate of the seventh MOSFET M1C serves as the second differential input terminal of the operational amplifier circuit. The eighth MOSFET M1D and the ninth MOSFET M1E constitute the current mirror in the operational amplifier circuit. The drain of the eighth MOSFET M1D is connected to the drain of the sixth MOSFET M1B, the gate of the eighth MOSFET M1D, and the gate of the ninth MOSFET M1E. The drain of the ninth MOSFET M1E is connected to the drain of the seventh MOSFET M1C. The sources of the eighth MOSFET M1D and the ninth MOSFET M1E are connected to the power supply ground. The drain of the ninth MOSFET M1E serves as the output terminal of the operational amplifier circuit.

[0051] In addition, the gate of the fifth MOSFET M1A is used for power-on control so that the fifth MOSFET M1A is turned on after the input power supply is powered on to form the quiescent current of the operational amplifier circuit.

[0052] Furthermore, the operational amplifier circuit also includes a tenth MOSFET M1F and an eleventh MOSFET M1G. The gates of the tenth MOSFET M1F and the eleventh MOSFET M1G are connected to the drain of the ninth MOSFET M1E. The sources of the tenth MOSFET M1F and the eleventh MOSFET M1G are connected to the power supply ground. The drain of the tenth MOSFET M1F serves as the first output terminal of the operational amplifier circuit and is connected to the source of the first MOSFET M2A. The drain of the eleventh MOSFET M1G serves as the second output terminal of the operational amplifier circuit and is connected to the source of the third MOSFET M1B.

[0053] The function of the op-amp clamping unit is to ensure that the voltages at the differential input terminals of the op-amp are approximately equal when the circuit is working normally, thereby ensuring the normal operation of the bandgap reference.

[0054] Specifically, the source of M1A is connected to "VIN", and its drain is connected to the source of the amplifier's differential input pair (M1B, M1C). In this configuration, M1A provides quiescent current to the five-transistor amplifier. The gates of the differential input pair (M1B, M1C) serve as the differential inputs of the operational amplifier, and are connected to the drains of M2A and M2B in the bandgap reference unit, respectively. The drains of the differential input pair (M1B, M1C) are connected to the drains of the current mirrors (M1D, M1E), respectively. The sources of the current mirrors (M1D, M1E) are connected to the reference ground "GND".

[0055] In some examples, the bandgap reference current source may also include a startup circuit, which includes a fourth resistor R5, a twelfth MOSFET M3B, the drain of the twelfth MOSFET M3B being connected to the gate of the first MOSFET M2A and the drain of the fourth MOSFET M2D, the gate of the twelfth MOSFET M3B being connected to the power supply ground, and the source of the twelfth MOSFET M3B being connected to the power supply ground through the fourth resistor R5; wherein the twelfth MOSFET M3B is a depletion-type MOSFET.

[0056] In some examples, the startup circuit also includes a fifth resistor R4 and a thirteenth MOSFET M3A. One end of the fifth resistor R4 is connected to the input power supply, and the other end of the fifth resistor R4 is connected to the source of the thirteenth MOSFET M3A. The drain and source of the thirteenth MOSFET M3A are connected to each other, and the gate of the thirteenth MOSFET M3A is connected to the drain of the first MOSFET M2A.

[0057] In some examples, the startup circuit also includes a fourteenth MOSFET M3C, the drain of which is connected to the source of the thirteenth MOSFET M3B, the source of which is connected to the power supply ground, and the gate of which is connected to the output of the operational amplifier circuit (such as the drain of M1E in the aforementioned example).

[0058] It should be noted that the connection relationship between M3A, M3B, M3C and the current-limiting resistors R4 and R5 in the startup unit is as follows: one end of resistor R4 is connected to the voltage "VIN", and the other end is connected to the source of M3A. The gate of M3A is connected to the gate of the differential input transistor M1B of the op-amp, and its drain is connected together with the source of M3B and one end of resistor R5. In practice, M3B is a depletion-type MOSFET (Vth approximately equal to -100mV), and the drain of M3B can also be connected together with the gate of the subsequent circuit (such as the gate of M4A in the output unit) and the drain of M2D in the bandgap reference unit, with its gate connected to the voltage "GND". The other end of resistor R5 is connected to the voltage "GND".

[0059] Based on the same inventive concept, this specification also provides a low-dropout linear regulator and a low-dropout linear regulator based on the current source of the above example.

[0060] like Figure 1 This diagram illustrates a low-dropout linear regulator comprising: a bandgap reference current source, a power MOSFET, and an adjustment circuit as described in any of the examples above. The adjustment circuit includes a third transistor Q3 and a sixth resistor R6.

[0061] The output terminal of the bandgap reference current source (such as the base of Q2 in the previous example) is connected to the base of the third transistor Q3. The emitter of the third transistor Q3 is connected to the power supply ground. The collector of the third transistor Q3 is connected to the base of the third transistor Q3 and one end of the sixth resistor R6. The other end of the sixth resistor R6 is connected to the drain of the power MOSFET M4A. The source of the power MOSFET M4A is connected to the input power supply. The drain of the power MOSFET M4A serves as the output terminal (VOUT) of the voltage regulator. The gate of the power MOSFET M4A is used for power-on control so that the power MOSFET M4A is turned on after the input power supply is powered on, so as to provide an output voltage to the outside through the output terminal of the voltage regulator.

[0062] Compared with existing bandgap reference circuits, the bandgap reference type LDO of the present invention has a stronger load-carrying capacity and a smaller load regulation, and is applicable to a wider range of applications.

[0063] In some examples, the low-dropout linear regulator further includes a filter capacitor C2 and / or a Miller capacitor C1, wherein the filter capacitor C2 is connected between the drain of the power MOSFET M4A and the power supply ground for output filtering of the regulator; the Miller capacitor C1 is connected between the gate and drain of the power MOSFET M4A to provide Miller compensation for the power MOSFET M4A, thereby compensating for the phase margin of the circuit and making the circuit more stable.

[0064] In practice, the capacitor can be a plate capacitor. In this case, the source of power transistor M4A is connected to voltage "VIN", the gate is connected to the upper plate of capacitor C1, and the drain is connected to the lower plate of capacitor C1, the upper plate of Zener capacitor C2, and one end of resistor R6. The other end of resistor R6 is connected to the base and collector of transistor Q3, and the emitter of Q3 is connected to voltage "GND". The lower plate of Zener capacitor C2 is connected to voltage "GND".

[0065] Based on the same inventive concept, this specification also provides a power manager, comprising: a bandgap reference current source as described in any of the foregoing examples in this specification, or a low dropout linear regulator as described in any of the foregoing examples in this specification, wherein the bandgap reference current source is used to provide an output current proportional to temperature; and the low dropout linear regulator is used to provide a supply voltage.

[0066] Below, on Figure 1 Explanation of the working principle of the schematic circuit unit:

[0067] 1. M2C, M2D, and M3B are depletion-type MOSFETs with a threshold voltage of approximately -100mV.

[0068] 2. The bandgap reference unit (first bandgap reference and second bandgap reference) is used to generate the bandgap reference PTAT current, which is replicated to the output unit through the transistor current mirror.

[0069] 3. The function of the op-amp clamping unit is to ensure that the voltages at the differential input terminals of the op-amp are approximately equal when the circuit is working normally, thereby ensuring the normal operation of the bandgap reference.

[0070] 4. Working Principle of the Start-up Unit: The start-up unit is used to initially start the entire circuit. When the circuit is working normally, the start-up unit does not operate, reducing static losses. When the circuit is not yet working normally, the gate and source of M3B in the start-up unit are both zero. At this time, the VGS voltage of this MOSFET is zero because the Vth of this MOSFET is -100mV, and the MOSFET is in the conducting state. Because M3B is in the conducting state, it pulls down the voltage at the drain of the MOSFET and the point connected to the drain (the gate of MOSFETs M4A and M1A). When the input voltage VIN is applied, the absolute value of VGS of MOSFETs M4A and M1A will increase, the MOSFETs will conduct, a static current will be generated in the circuit, and the circuit will start working. After the circuit is working normally, current will be generated in branches R4, M3A, and R5. After the current flows through resistor R5, a voltage is generated at the upper end of the resistor and the source of M3B. This voltage will make the VGS of MOSFET M3B less than -100mV. Therefore, when the circuit is working normally, MOSFET M3B is in the off state. To minimize the static current during circuit operation, current limiting can be applied to the branch (composed of R4, M3A, and R5) as in the previous example. This current limiting operation is performed through R5 and M3C. During normal operation, M3C conducts some current while increasing the resistance of R5 to limit the current in this branch.

[0071] 5. The LDO circuit can output a temperature-independent bandgap reference voltage, approximately 1.25V (this value can be adjusted by changing resistor R6 as needed, but is not limited here). The bandgap reference unit generates a reference current PTAT, which is transmitted to the output unit through transistor current mirrors Q1, Q2, and Q3. This current, along with resistor R6, generates a voltage with a positive temperature coefficient. The sum of this voltage and the negative temperature coefficient voltage VBE generated by transistor Q3 equals the output voltage. Clamping is achieved through the input differential pair transistors in the operational amplifier unit, ensuring that the drain voltages of transistors M2C and M2D in the bandgap reference unit are approximately equal. Furthermore, the depletion-mode MOSFETs M2C and M2D in the bandgap reference unit further ensure that the collector voltages of transistors Q1 and Q2 are equal, while also ensuring that transistors Q1 and Q2 operate in the saturation region.

[0072] 6. Design a negative feedback loop in the circuit based on the operating characteristics of the transistor (reference) Figure 2 (Illustrative image). For example: [Example image would be inserted here] Figure 1As shown, when the output voltage suddenly increases, the base voltages of transistors Q1 and Q2 will be pulled up, due to... Figure 2 It can be seen that the current flowing through Q2 is higher than the current flowing through Q1. The branch current of Q2 is replicated to the drain of MOSFET M2B through the current mirror pair M2A and M2B. At this time, the pull-up current of MOSFET M2D is greater than the pull-down current, so the drain voltage of MOSFET M2D will be pulled up. At the same time, the gate voltage of M4A, which is connected to the drain of M2D, will also be pulled up. Since M4A is a PMOS transistor, when the gate voltage increases, the pull-up force will weaken, and the drain output voltage VOUT of M4A will decrease. This forms a negative feedback loop to stabilize the circuit.

[0073] 7. For example Figure 1 In the circuit diagram shown, MOSFET M4A is the power transistor of the circuit, and the size of the power transistor determines the load capacity of the circuit. Figure 1 In the circuit diagram shown, capacitor C1 is a Miller compensation capacitor introduced into the circuit to compensate for the phase margin of the circuit and make the circuit more stable.

[0074] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0075] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A bandgap reference current source, characterized in that, include: First bandgap reference circuit, second bandgap reference circuit, operational amplifier clamping circuit; The first bandgap reference circuit includes a first resistor, a first MOSFET, a second MOSFET, and a first transistor; the second bandgap reference circuit includes a second resistor, a third MOSFET, a fourth MOSFET, a second transistor, and a third resistor; the operational amplifier clamping circuit includes an operational amplifier circuit; In this circuit, one end of the first resistor is connected to the input power supply, and the other end is connected to the source of the first MOSFET. The gate of the first MOSFET is connected to the gate of the third MOSFET, the drain of the first MOSFET, and the first differential input terminal of the operational amplifier circuit. The drain of the first MOSFET is connected to the drain of the second MOSFET. The gate of the second MOSFET is connected to the gate of the fourth MOSFET, the base of the first transistor, and the base of the second transistor. The source of the second MOSFET is connected to the collector of the first transistor. The emitter of the first transistor is connected to the power supply ground. One end of the second resistor is connected to the input power supply, and the other end is connected to the source of the third MOSFET. The drain of the third MOSFET is connected to the second differential input terminal of the operational amplifier circuit and the drain of the fourth MOSFET. The source of the fourth MOSFET is connected to the collector of the second transistor. The emitter of the second transistor is connected to the power supply ground through the third resistor. The output terminal of the operational amplifier circuit is connected to the source of the first MOSFET and the source of the third MOSFET. The base of the first transistor serves as the output terminal of a current source to provide an output current proportional to temperature.

2. The bandgap reference current source according to claim 1, characterized in that, The operational amplifier circuit includes a fifth MOSFET, a sixth MOSFET, a seventh MOSFET, an eighth MOSFET, and a ninth MOSFET; The source of the fifth MOSFET is connected to the input power supply, and the drain of the fifth MOSFET is connected to the source of the sixth MOSFET and the source of the seventh MOSFET. The gate of the sixth MOSFET serves as the first differential input terminal of the operational amplifier circuit. The gate of the seventh MOSFET serves as the second differential input terminal of the operational amplifier circuit. The eighth and ninth MOSFETs form a current mirror, wherein the drain of the eighth MOSFET is connected to the drain of the sixth MOSFET, the gate of the eighth MOSFET, and the gate of the ninth MOSFET, and the drain of the ninth MOSFET is connected to the drain of the seventh MOSFET. The sources of the eighth and ninth MOSFETs are connected to the power supply ground. The drain of the ninth MOSFET serves as the output terminal of the operational amplifier circuit. The gate of the fifth MOSFET is used for power-on control so that the fifth MOSFET is turned on after the input power is applied to form the quiescent current of the operational amplifier circuit.

3. The bandgap reference current source according to claim 2, characterized in that, The operational amplifier circuit also includes a tenth MOSFET and an eleventh MOSFET. The gates of the tenth and eleventh MOSFETs are connected to the drain of the ninth MOSFET, and the sources of the tenth and eleventh MOSFETs are connected to the power supply ground. The drain of the tenth MOSFET serves as the first output terminal of the operational amplifier circuit and is connected to the source of the first MOSFET. The drain of the eleventh MOSFET serves as the second output terminal of the operational amplifier circuit and is connected to the source of the third MOSFET.

4. The bandgap reference current source according to claim 2, characterized in that, The bandgap reference current source also includes a startup circuit, which includes a fourth resistor and a twelfth MOS transistor. The drain of the twelfth MOS transistor is connected to the gate of the fifth MOS transistor and the drain of the fourth MOS transistor. The gate of the twelfth MOS transistor is connected to the power supply ground, and the source of the twelfth MOS transistor is connected to the power supply ground through the fourth resistor. The twelfth MOSFET is a depletion-type MOSFET.

5. The bandgap reference current source according to claim 4, characterized in that, The startup circuit also includes a fifth resistor and a thirteenth MOSFET. One end of the fifth resistor is connected to the input power supply, and the other end of the fifth resistor is connected to the source of the thirteenth MOSFET. The drain of the thirteenth MOSFET is connected to the source of the twelfth MOSFET, and the gate of the thirteenth MOSFET is connected to the drain of the first MOSFET.

6. The bandgap reference current source according to claim 5, characterized in that, The startup circuit also includes a fourteenth MOS transistor, the drain of which is connected to the source of the thirteenth MOS transistor, the source of which is connected to the power supply ground, and the gate of which is connected to the output terminal of the operational amplifier circuit.

7. The bandgap reference current source according to any one of claims 1-6, characterized in that, The second and fourth MOSFETs are depletion-type MOSFETs; And / or, the resistance values ​​of the first resistor and the second resistor are equal; And / or, the first MOSFET and the third MOSFET are a matched pair; And / or, the second MOSFET and the fourth MOSFET are a matched pair.

8. A low-dropout linear voltage regulator, characterized in that, include: The bandgap reference current source as described in any one of claims 1-7; Power MOSFET; The adjustment circuit includes a third transistor and a sixth resistor. In this configuration, the output terminal of the bandgap reference current source is connected to the base of the third transistor, the emitter of the third transistor is connected to the power supply ground, the collector of the third transistor is connected to the base of the third transistor and one end of the sixth resistor, the other end of the sixth resistor is connected to the drain of the power MOSFET, the source of the power MOSFET is connected to the input power supply, the drain of the power MOSFET serves as the output terminal of the voltage regulator, and the gate of the power MOSFET is used for power-on control so that the power MOSFET is turned on after the input power supply is powered on, so as to provide an output voltage to the outside through the output terminal of the voltage regulator.

9. The low-dropout linear regulator according to claim 8, characterized in that, The low-dropout linear regulator further includes a filter capacitor and / or a Miller capacitor, wherein the filter capacitor is connected between the drain of the power MOSFET and the power supply ground for output filtering of the regulator; the Miller capacitor is connected between the gate and drain of the power MOSFET for compensation of the power MOSFET.

10. A power manager, characterized in that, include: The bandgap reference current source as described in any one of claims 1-7, and the low dropout linear regulator as described in any one of claims 8-9, wherein the bandgap reference constant current source is used to provide an output current proportional to temperature; and the low dropout linear regulator is used to provide a supply voltage.

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