Voltage stabilizing control circuit, voltage stabilizing control method, and low-dropout linear voltage stabilizing circuit

Abstract

The application provides a voltage stabilizing control circuit, a voltage stabilizing control method and a low-voltage-difference linear voltage stabilizing circuit. The voltage stabilizing control circuit is used for controlling an output voltage, and comprises an operational amplifier circuit, a current sampling circuit and a compensation circuit. A first input end of the operational amplifier circuit is used for acquiring a feedback signal representing the output voltage, and an output end of the operational amplifier circuit is used for coupling a control end of an output power tube. The current sampling circuit is used for generating a current sampling signal representing a current flowing through the output power tube. A first end of the compensation circuit is coupled with the current sampling circuit, a second end of the compensation circuit is coupled with the operational amplifier circuit, and the compensation circuit is used for adjusting a compensation resistor of the operational amplifier circuit according to the current sampling signal. The voltage stabilizing control circuit, the voltage stabilizing control method and the low-voltage-difference linear voltage stabilizing circuit disclosed by the application effectively improve the loop stability of the voltage stabilizing control circuit under various load conditions through dynamic compensation of the compensation circuit.

Description

Technical Field

[0001] This invention belongs to the field of power electronics and relates to a voltage regulation technology, particularly a voltage regulation control circuit, a voltage regulation control method, and a low-dropout linear voltage regulator circuit. Background Technology

[0002] LDO (low dropout regulator) is a type of low-dropout linear regulator widely used in various DC voltage regulation circuits due to its advantages such as low noise, high power supply rejection ratio, and low power consumption. Low dropout refers to a small difference between the input and output voltages, typically as small as several hundred mV. When the input power supply voltage VIN varies within a certain range, the output voltage VOUT remains constant. LDOs are widely used in integrated circuits to power circuits.

[0003] For LDOs with large external capacitors at the output, ensuring stability is a key design consideration. Existing LDO circuits of this type use a fixed compensation method, meaning the values ​​of the compensation capacitor and resistor are fixed. This method can guarantee loop stability when the load current changes little. However, with larger load current variations, the stability of LDOs with fixed compensation deteriorates. This is because, with a large output capacitor and a light load, the output pole of this type of LDO is the dominant pole, and within the unity-gain bandwidth, there is a secondary pole and a zero. When the secondary pole and zero cancel each other out, there is only one dominant pole in the entire loop, resulting in a stable loop. When the load coupled to the output is heavy, the dominant pole shifts to a higher frequency, sometimes even higher than the frequency of the secondary pole. While the secondary pole and zero still cancel each other out, the unity-gain bandwidth increases due to the change in the dominant pole's position, allowing other poles to enter the loop, thus causing instability. The greater the change in load current, that is, the greater the current under heavy load, the worse its stability will be, as can be seen from the above analysis.

[0004] In view of this, there is a need to provide a new structure or control method to solve at least some of the above problems. Summary of the Invention

[0005] In view of one or more problems in the prior art, the present invention proposes a voltage regulation control circuit, a voltage regulation control method, and a low dropout linear voltage regulator circuit.

[0006] According to one aspect of the present invention, a voltage regulation control circuit is disclosed, which is used to control the output voltage, the voltage regulation control circuit comprising:

[0007] An operational amplifier circuit has a first input terminal used to obtain a feedback signal characterizing the output voltage, a second input terminal used to obtain a reference voltage, and an output terminal used to couple to the control terminal of the output power transistor to control the output voltage.

[0008] A current sampling circuit, whose input is coupled to the output power transistor, is used to generate a current sampling signal characterizing the current flowing through the output power transistor; and

[0009] The compensation circuit has a first terminal coupled to a current sampling circuit and a second terminal coupled to the output terminal of an operational amplifier circuit. It is used to adjust the compensation resistor of the operational amplifier circuit according to the current sampling signal. The compensation resistor value of the operational amplifier circuit is negatively correlated with the current sampling signal.

[0010] As an embodiment of the present invention, the compensation circuit includes:

[0011] The regulating circuit has its first terminal coupled to the input voltage and its third terminal coupled to the output terminal of the current sampling circuit; and

[0012] The second capacitor has its first end coupled to the second end of the regulating circuit, and its second end coupled to the output end of the operational amplifier circuit.

[0013] In one embodiment, the regulating circuit includes an eleventh transistor, the first terminal of which is coupled to the input voltage, and the second terminal of which is coupled to the first terminal of a second capacitor. The regulating circuit controls the conduction level of the eleventh transistor according to the current sampling signal.

[0014] As an embodiment of the present invention, the adjustment circuit includes:

[0015] The eleventh transistor has its first terminal coupled to the input voltage;

[0016] The twelfth transistor has its first terminal coupled to the first terminal of the eleventh transistor, and its second terminal coupled to the control terminal of the eleventh transistor and the control terminal of the twelfth transistor, respectively.

[0017] The thirteenth transistor has its first terminal coupled to the second terminal of the twelfth transistor, and its second terminal coupled to ground; and

[0018] The fourteenth transistor has its first terminal coupled to the second terminal of the twelfth transistor, its second terminal coupled to ground, and its control terminal coupled to the output terminal of the current sampling circuit.

[0019] As an embodiment of the present invention, the current sampling circuit includes:

[0020] The sampling resistor has its first terminal coupled to the second terminal of the output power transistor, and its second terminal coupled to ground; and

[0021] The voltage-to-current conversion circuit has an input terminal coupled to a sampling resistor to obtain a sampling voltage, and an output terminal that outputs a current sampling signal, which is used to generate a current sampling signal based on the sampling voltage.

[0022] As an embodiment of the present invention, the current sampling circuit includes:

[0023] The fifteenth transistor has its first terminal coupled to the input voltage, and its control terminal coupled to the control terminal of the output power transistor.

[0024] The sixteenth transistor has its first terminal coupled to the second terminal of the fifteenth transistor;

[0025] The seventeenth transistor has its first terminal coupled to the second terminal of the output power transistor, and its second terminal coupled to the control terminal of the sixteenth transistor and the control terminal of the seventeenth transistor respectively.

[0026] The eighteenth transistor has its first terminal coupled to the second terminal of the sixteenth transistor, its second terminal coupled to ground, and its control terminal coupled to both the compensation circuit and the first terminal of the eighteenth transistor; and

[0027] The nineteenth transistor has its first terminal coupled to the second terminal of the seventeenth transistor, its second terminal coupled to ground, and its control terminal coupled to a second voltage.

[0028] As an embodiment of the present invention, the voltage regulation control circuit further includes: a level conversion circuit, the input terminal of which is coupled to the output terminal of the operational amplifier circuit, and the output terminal of which is coupled to the control terminal of the output power transistor.

[0029] As an embodiment of the present invention, the level conversion circuit includes:

[0030] The twentieth transistor has its first terminal coupled to an input voltage and its control terminal coupled to a first voltage; and

[0031] The 21st transistor has its first terminal coupled to the second terminal of the 20th transistor, its control terminal coupled to the output terminal of the operational amplifier circuit, and its second terminal coupled to the fourth resistor; the first terminal of the 21st transistor is used to couple to the control terminal of the output power transistor.

[0032] In one embodiment of the present invention, the voltage regulation control circuit further includes a tail current generation circuit, which generates a tail current to provide the tail current required for operation of the operational amplifier circuit. The tail current generation circuit includes:

[0033] A first current source, whose first terminal is coupled to the input voltage, is used to generate a first current;

[0034] The ninth transistor has its first terminal and control terminal coupled to the output terminal of the first current source, and its second terminal coupled to ground; and

[0035] The tenth transistor has its first terminal coupled to an operational amplifier circuit, its second terminal coupled to ground, and its control terminal coupled to the control terminal of the ninth transistor.

[0036] According to another aspect of the present invention, a low-dropout linear regulator circuit is disclosed, the low-dropout linear regulator circuit including a voltage regulation control circuit as described in any of the preceding claims, the voltage regulation control circuit controlling the output power transistor in the low-dropout linear regulator circuit thereby controlling the output voltage.

[0037] According to another aspect of the present invention, a voltage regulation control method is disclosed, which is used to control a voltage regulation control circuit. The voltage regulation control method includes:

[0038] The operational amplifier circuit controls the output power transistor to control the output voltage based on the reference voltage and the feedback signal characterizing the output voltage;

[0039] Generate a current sampling signal that characterizes the current flowing through the output power transistor;

[0040] The compensation resistor of the operational amplifier circuit is adjusted according to the current sampling signal, and the value of the compensation resistor of the operational amplifier circuit is negatively correlated with the current sampling signal.

[0041] As an embodiment of the present invention, the voltage regulation control circuit includes an operational amplifier circuit and a compensation circuit. The compensation circuit is coupled to the output terminal of the operational amplifier circuit and includes an eleventh transistor. The compensation circuit controls the conduction degree of the eleventh transistor according to the current sampling signal, thereby adjusting the compensation resistor of the operational amplifier circuit.

[0042] In one embodiment of the present invention, the sampling resistor in the voltage regulation control circuit is coupled to the output power transistor, and the step of generating a current sampling signal characterizing the current flowing through the output power transistor includes:

[0043] The sampling voltage is obtained through the sampling resistor, and a current sampling signal is generated based on the sampling voltage. The current sampling signal is a current signal.

[0044] This invention proposes a voltage regulation control circuit, a voltage regulation control method, and a low-dropout linear voltage regulator circuit. The voltage regulation control circuit controls the output voltage and includes an operational amplifier circuit, a current sampling circuit, and a compensation circuit. The first input terminal of the operational amplifier circuit is used to obtain a feedback signal characterizing the output voltage, the second input terminal is used to obtain a reference voltage, and the output terminal of the operational amplifier circuit is coupled to the control terminal of the output power transistor to control the output voltage. The input terminal of the current sampling circuit is coupled to the output power transistor, and the current sampling circuit generates a current sampling signal characterizing the current flowing through the output power transistor. The first terminal of the compensation circuit is coupled to the current sampling circuit, and the second terminal of the compensation circuit is coupled to the output terminal of the operational amplifier circuit. The compensation circuit adjusts the compensation resistor of the operational amplifier circuit according to the current sampling signal; the compensation resistor value of the operational amplifier circuit is negatively correlated with the current sampling signal. This invention discloses a voltage regulation control circuit, a voltage regulation control method, and a low-dropout linear voltage regulator circuit, which effectively improves the loop stability of the voltage regulation control circuit under various load conditions through dynamic compensation by the compensation circuit. Attached Figure Description

[0045] The accompanying drawings are provided to further illustrate the invention and, together with the description, serve to explain embodiments of the invention, but do not constitute a limitation thereof. In the drawings:

[0046] Figure 1 A schematic diagram of the circuit structure of a voltage regulation control circuit according to an embodiment of the present invention is shown;

[0047] Figure 2 A schematic diagram of the circuit structure of a voltage regulation control circuit according to another embodiment of the present invention is shown;

[0048] Figure 3 A schematic diagram of the circuit structure of a compensation circuit according to an embodiment of the present invention is shown;

[0049] Figure 4 A schematic diagram of the circuit structure of a current sampling circuit according to an embodiment of the present invention is shown;

[0050] Figure 5 A schematic diagram of the circuit structure of a voltage regulation control circuit according to another embodiment of the present invention is shown;

[0051] Figure 6 A schematic diagram of the circuit structure of a level conversion circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0052] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0053] The description in this section pertains to only a few typical embodiments, and the present invention is not limited to the scope of the embodiments described. Combinations of different embodiments, substitution of some technical features in different embodiments, and substitution of similar or identical prior art with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0054] The terms "coupled" or "connected" in this specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection through an electrically conductive medium like a conductor, which may contain parasitic inductance or capacitance. It can also be a connection through intermediate circuits or components described in the embodiments of this specification. Indirect connections may also include connections through other active or passive devices that achieve the same or similar functions, such as connections through switches, signal amplification circuits, follower circuits, or other circuits or components. "A plurality of" or "more" indicates two or more. Furthermore, in this invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship or order between these technical features.

[0055] like Figure 1 As shown, an embodiment of the present invention discloses a voltage regulation control circuit. This circuit controls an output power transistor 10 to control the output voltage VOUT, thereby achieving a regulated output. The output power transistor 10 is a three-terminal device, including a control terminal, a first terminal, and a second terminal. The first terminal of the output power transistor 10 is coupled to the input voltage VIN. The voltage regulation control circuit includes an operational amplifier circuit 11, a current sampling circuit 14, and a compensation circuit 13. The first input terminal of the operational amplifier circuit 11 is used to obtain a feedback signal characterizing the output voltage VOUT, and the second input terminal is used to obtain a reference voltage. The output terminal of the operational amplifier circuit 11 is coupled to the control terminal of the output power transistor 10. The operational amplifier circuit 11 controls the output power transistor 10 according to the feedback signal and the reference voltage, thereby controlling the output voltage VOUT. In a specific embodiment, the operational amplifier circuit is an operational amplifier. Figure 1 As shown, the input terminal of the current sampling circuit 14 is coupled to the second terminal of the output power transistor 10. The current sampling circuit 14 is used to generate a current sampling signal characterizing the current flowing through the output power transistor 10. The first terminal of the compensation circuit 13 is coupled to the output terminal of the current sampling circuit 14, and the second terminal of the compensation circuit 13 is coupled to the output terminal of the operational amplifier circuit 11. The compensation circuit 13 is used to adjust the compensation resistor of the operational amplifier circuit 11 according to the current sampling signal. The compensation resistor value of the operational amplifier circuit is negatively correlated with the current sampling signal, and the compensation resistor value is the resistance value of the compensation resistor of the operational amplifier circuit.

[0056] In one embodiment, the voltage regulation control circuit further includes an output voltage feedback circuit 12, the input terminal of which is coupled to the output voltage terminal to obtain the output voltage. The output voltage feedback circuit 12 generates a feedback signal characterizing the output voltage based on the output voltage. In one embodiment, the voltage regulation control circuit further includes an output power transistor. In another embodiment, the voltage regulation control circuit may not include an output power transistor.

[0057] like Figure 2 As shown, in one embodiment of the present invention, the voltage regulation control circuit includes an operational amplifier circuit 21, an output voltage feedback circuit 22, a compensation circuit 23, and a current sampling circuit 24. The operational amplifier circuit 21 includes a first transistor M1, a second transistor M2, a third transistor M3, a fourth transistor M4, a fifth transistor M5, a sixth transistor M6, a seventh transistor M7, and an eighth transistor M8. The first terminal of the first transistor M1 is coupled to the input voltage. The first terminal of the second transistor M2 is coupled to the input voltage, and the control terminal of the second transistor M2 is coupled to the control terminal of the first transistor M1 and the second terminal of the second transistor M2. The first terminal of the third transistor M3 is coupled to the input voltage, and the second terminal of the third transistor M3 is coupled to its control terminal. The first terminal of the fourth transistor M4 is coupled to the input voltage, and its control terminal is coupled to the control terminal of the third transistor M3. The first terminal of the fifth transistor M5 is coupled to the second terminal of the second transistor M2, and its control terminal is coupled to a reference signal VREF. The first terminal of the sixth transistor M6 is coupled to the second terminal of the third transistor M3, and the second terminal of the sixth transistor M6 is coupled to the second terminal of the fifth transistor M5. The control terminal of the sixth transistor M6 is coupled to the feedback signal VFB. The first terminal of the seventh transistor M7 is coupled to the second terminal of the first transistor M1 and the control terminal of the seventh transistor M7, respectively, and the second terminal of the seventh transistor M7 is grounded. The first terminal of the eighth transistor M8 is coupled to the second terminal of the fourth transistor M4, and the second terminal of the eighth transistor M8 is grounded. The control terminal of the eighth transistor M8 is coupled to the control terminal of the seventh transistor M7, and the first terminal of the eighth transistor M8 can be used as the output terminal of the operational amplifier circuit 21. The above embodiment is one implementation of the operational amplifier circuit, and other operational amplifier circuit structures can be selected according to specific application needs.

[0058] like Figure 2In one embodiment shown, the voltage regulation control circuit further includes a tail current generation circuit. The tail current generation circuit generates a tail current to provide the operational amplifier circuit 21 with the tail current required for operation. The tail current generation circuit includes a first current source I1, a ninth transistor M9, and a tenth transistor M10. The first terminal of the first current source I1 is coupled to the input voltage VIN, and the first current source I1 generates a first current. The first terminal and the control terminal of the ninth transistor M9 are respectively coupled to the output terminal of the first current source I1, and the second terminal of the ninth transistor M9 is coupled to ground. The first terminal of the tenth transistor M10 is coupled to the second terminal of the fifth transistor M5 in the operational amplifier circuit 21, and the second terminal of the tenth transistor M10 is coupled to ground. The control terminal of the tenth transistor M10 is coupled to the control terminal of the ninth transistor M9.

[0059] In such Figure 2 In one embodiment shown, the compensation circuit 23 includes an adjustment circuit 231 and a second capacitor C2. The first terminal of the adjustment circuit 231 is coupled to the input voltage VIN, and the third terminal of the adjustment circuit 231 is coupled to the output terminal of the current sampling circuit 24. The first terminal of the second capacitor C2 is coupled to the second terminal of the adjustment circuit 231, and the second terminal of the second capacitor C2 is coupled to the output terminal of the operational amplifier circuit 21. The input terminal of the current sampling circuit 24 is coupled to the second terminal of the output power transistor Q1, and the current sampling circuit 24 samples the current flowing through the output power transistor Q1 and generates a current sampling signal. The output voltage feedback circuit 22 includes a first resistor R1 and a second resistor R2. The first terminal of the first resistor R1 is coupled to the second terminal of the output power transistor Q1, the first terminal of the second resistor R2 is coupled to the second terminal of the first resistor R1, the second terminal of the second resistor R2 is coupled to ground, and the first terminal of the second resistor R2 outputs a feedback signal VFB. The second terminal of the output power transistor Q1 is also coupled to the first capacitor C1.

[0060] In one specific embodiment, the regulating circuit includes an eleventh transistor. The first terminal of the eleventh transistor is coupled to the input voltage, and the second terminal of the eleventh transistor is coupled to the first terminal of a second capacitor. The regulating circuit controls the conduction level of the eleventh transistor based on a current sampling signal. When the load increases, the current sampling signal increases, and the regulating circuit increases the conduction level of the eleventh transistor. When the load decreases, the current sampling signal decreases, and the regulating circuit decreases the conduction level of the eleventh transistor. In another specific embodiment, the regulating circuit includes a resistor regulating circuit, which adjusts the resistance value of the resistor regulating circuit based on the current sampling signal.

[0061] In one embodiment of the present invention, the output power transistor is one of a metal-oxide-semiconductor field-effect transistor (MOS transistor), a junction field-effect transistor (JFET), or an insulated-gate bipolar transistor (IGBT). Preferably, the output power transistor is a PMOS transistor, with its drain coupled to the input voltage, its source coupled to the output voltage, and its gate coupled to the output terminal of the operational amplifier circuit.

[0062] In such Figure 3 In another embodiment shown, the compensation circuit 33 includes an adjustment circuit and a second capacitor C2. The adjustment circuit includes an eleventh transistor M11, a twelfth transistor M12, a thirteenth transistor M13, a fourteenth transistor M14, and a third resistor R3. The first terminal of the eleventh transistor M11 is coupled to the input voltage VIN. The first terminal of the twelfth transistor M12 is coupled to the first terminal of the eleventh transistor M11, and the second terminal of the twelfth transistor M12 is coupled to the control terminals of both the eleventh transistor M11 and the twelfth transistor M12. The third resistor R3 is connected in series with the second capacitor C2. The first terminal of the thirteenth transistor M13 is coupled to the second terminal of the twelfth transistor M12, the second terminal of the thirteenth transistor M13 is coupled to ground, and the control terminal of the thirteenth transistor M13 is coupled to the third voltage V3. The first terminal of the fourteenth transistor M14 is coupled to the second terminal of the twelfth transistor M12, the second terminal of the fourteenth transistor M14 is coupled to ground, and the control terminal of the fourteenth transistor M14 is coupled to the output terminal of the current sampling circuit.

[0063] In one embodiment of the present invention, the current sampling circuit includes a sampling resistor and a voltage-to-current conversion circuit. A first terminal of the sampling resistor is coupled to a second terminal of the output power transistor, and the second terminal of the sampling resistor is coupled to ground. The input terminal of the voltage-to-current conversion circuit is coupled to the sampling resistor to obtain a sampling voltage, and the output terminal of the voltage-to-current conversion circuit outputs a current sampling signal. The voltage-to-current conversion circuit is used to generate a current sampling signal based on the sampling voltage, and the current sampling signal is a current signal.

[0064] In another embodiment of the invention, such as Figure 4As shown, the current sampling circuit 34 includes a fifteenth transistor M15, a sixteenth transistor M16, a seventeenth transistor M17, an eighteenth transistor M18, and a nineteenth transistor M19. The first terminal of the fifteenth transistor M15 is coupled to the input voltage VIN, and its control terminal is coupled to the control terminal of the output power transistor Q1. The first terminal of the sixteenth transistor M16 is coupled to the second terminal of the fifteenth transistor M15. The first terminal of the seventeenth transistor M17 is coupled to the second terminal of the output power transistor Q1, and its second terminal is coupled to both the control terminals of the sixteenth transistor M16 and the seventeenth transistor M17. The first terminal of the eighteenth transistor M18 is coupled to the second terminal of the sixteenth transistor M16, and its second terminal is grounded. Its control terminal is coupled to both the compensation circuit and the first terminal of the eighteenth transistor M18. The first terminal of the nineteenth transistor M19 is coupled to the second terminal of the seventeenth transistor M17, and its second terminal is grounded. Its control terminal is coupled to the second voltage V2. The fifteenth transistor is a current sampling transistor that samples the output current on the output power transistor Q1. The current sampling signal generated by the current sampling circuit is the current flowing through the eighteenth transistor M18. The eighteenth transistor M18 and the fourteenth transistor M14 form a current mirror, so the mirror current (i.e., the current flowing through the fourteenth transistor M14) can be obtained from the current flowing through the eighteenth transistor M18.

[0065] In one embodiment of the present invention, such as Figure 5 As shown, the voltage regulation control circuit includes an operational amplifier circuit 41, an output voltage feedback circuit 42, a compensation circuit 43, a current sampling circuit 44, and a level conversion circuit 45. The input terminal of the level conversion circuit 45 is coupled to the output terminal of the operational amplifier circuit 41, and the output terminal of the level conversion circuit 45 is coupled to the control terminal of the output power transistor 40. The level conversion circuit 45 is used to perform level conversion on the output signal of the operational amplifier circuit.

[0066] like Figure 6 In one embodiment shown, the level conversion circuit 55 includes a twentieth transistor M20 and a twenty-first transistor M21. The first terminal of the twentieth transistor M20 is coupled to the input voltage VIN, and the control terminal of the twentieth transistor M20 is coupled to a first voltage V1. The first terminal of the twenty-first transistor M21 is coupled to the second terminal of the twentieth transistor M20. The control terminal of the twenty-first transistor M21 is coupled to the output terminal of the operational amplifier circuit, and the second terminal of the twenty-first transistor M21 is coupled to the first terminal of a fourth resistor R4, which is grounded. The first terminal of the twenty-first transistor is used to couple to the control terminal of the output power transistor.

[0067] In one embodiment of the present invention, each of the first to twenty-first transistors is one of a metal-oxide-semiconductor field-effect transistor (MOS transistor), a junction field-effect transistor (JFET transistor), or an insulated-gate bipolar transistor (IGBT transistor). Preferably, as Figure 2 As shown, transistors 1, 2, 3, and 4 are all PMOS transistors. Transistors 5, 6, 7, and 8 are all NMOS transistors. Transistors 9 and 10 are also NMOS transistors. Figure 3 As shown, transistors eleven and twelfth are PMOS transistors. Transistors thirteenth and fourteenth are NMOS transistors. Figure 4 As shown, transistors 15, 16, and 17 are all PMOS transistors. Transistors 18 and 19 are NMOS transistors. Transistors 20 and 21 are PMOS transistors.

[0068] Combination Figures 2-4 In one embodiment, the dominant pole of the voltage regulator control circuit is the output pole, and the secondary pole of the voltage regulator control circuit is located at the output terminal of the operational amplifier circuit (i.e., the first stage of the voltage regulator control circuit) (corresponding to the second terminal of the fourth transistor). The secondary pole of the voltage regulator control circuit is formed by the output resistor of the operational amplifier circuit and the second capacitor C2. Capacitor C2 and resistor RZ form a zero point, and resistor RZ is the compensation resistor of the operational amplifier circuit. The resistance value of resistor RZ is the sum of the equivalent resistance value of the eleventh transistor and the resistance value of the third resistor R3.

[0069] In one embodiment, the thirteenth transistor M13 and the ninth transistor M9 form a current mirror. In this embodiment, the current flowing through the thirteenth transistor M13 is a fixed current. The current flowing through the fourteenth transistor M14 is obtained by mirroring the current flowing through the eighteenth transistor M18. The current flowing through the twelfth transistor M12 is equal to the sum of the current flowing through the thirteenth transistor M13 and the current flowing through the fourteenth transistor M14. Therefore, the voltage VGS of the twelfth transistor M12 can vary with the load current. Correspondingly, the equivalent resistance value on the eleventh transistor M11 also varies with the load current, wherein the eleventh transistor M11 operates in the deep linear region.

[0070] In one embodiment, when the voltage regulation control circuit is under no-load, the current flowing through the fourteenth transistor M14 is 0, so the current flowing through the twelfth transistor M12 is equal to the current flowing through the thirteenth transistor M13. At this time, the absolute value of the voltage VGS of the twelfth transistor M12 is small, so the resistance value of resistor RZ is large. The zero and the secondary pole cancel each other out. Since the output impedance is very large at this time, the dominant pole is located at a low frequency, the unity-gain bandwidth is very low, and the system remains very stable. When the voltage regulation control circuit is under heavy load, the current flowing through the fourteenth transistor M14 increases, so the current flowing through the twelfth transistor M12 is equal to the sum of the current flowing through the thirteenth transistor M13 and the current flowing through the fourteenth transistor M14. At this time, the absolute value of the voltage VGS of the twelfth transistor M12 is large, so the resistance value of resistor RZ is small. The dominant pole shifts to a higher frequency due to the decrease in output impedance, and its frequency is closer to that of the secondary pole, forming a double dominant pole. At this point, adjusting the zero point to a higher frequency than under light load allows the amplitude-frequency response to decrease at a rate of -40dB / dec. This reduces the unity-gain bandwidth and avoids the influence of high-frequency poles (such as the pole corresponding to the control terminal of the sixth transistor) on the phase margin, thus ensuring stability. In this invention, dynamic compensation is achieved by introducing a compensation circuit. When the voltage regulator control circuit is under heavy load, shifting the zero point to a higher frequency range further reduces the unity-gain bandwidth and places other poles outside the unity-gain bandwidth, effectively solving the problem of stability under heavy load.

[0071] Another embodiment of the present invention discloses a low-dropout linear regulator circuit, which includes a voltage regulation control circuit as described in any of the preceding claims. The voltage regulation control circuit controls the output power transistor in the low-dropout linear regulator circuit to control the output voltage. In a specific embodiment, the low-dropout linear regulator circuit is a low-dropout linear regulator.

[0072] Another embodiment of the present invention discloses a voltage regulation control method for controlling a voltage regulation control circuit. The voltage regulation control method includes: an operational amplifier circuit controlling an output power transistor to control the output voltage based on a reference voltage and a feedback signal characterizing the output voltage; generating a current sampling signal characterizing the current flowing through the output power transistor; and adjusting a compensation resistor of the operational amplifier circuit based on the current sampling signal, wherein the value of the compensation resistor of the operational amplifier circuit is negatively correlated with the current sampling signal. In the present invention, the control steps of the operational amplifier circuit controlling the output power transistor to control the output voltage based on the reference voltage and the feedback signal characterizing the output voltage in the voltage regulation control method are not limited by the order of the steps.

[0073] In one embodiment of the present invention, the voltage regulation control circuit includes an operational amplifier circuit and a compensation circuit. The compensation circuit is coupled to the output terminal of the operational amplifier circuit and includes an eleventh transistor. The compensation circuit controls the conduction degree of the eleventh transistor according to the current sampling signal, thereby adjusting the compensation resistor of the operational amplifier circuit.

[0074] In another embodiment of the present invention, the sampling resistor in the voltage regulation control circuit is coupled to the output power transistor, and the step of generating a current sampling signal characterizing the current flowing through the output power transistor includes obtaining a sampling voltage through the sampling resistor, generating a current sampling signal based on the sampling voltage, wherein the current sampling signal is a current signal.

[0075] Those skilled in the art should know that the logic controls such as "high level" and "low level", "set" and "reset", "AND gate" and "OR gate", "non-inverting input" and "inverting input" in the logic control involved in the specification or drawings can be interchanged or changed, and the same function or purpose as the above embodiment can be achieved by adjusting the subsequent logic control.

[0076] The description and application of the present invention herein are illustrative and not intended to limit the scope of the invention to the embodiments described above. The effects or advantages described in the specification may not be apparent in actual experimental cases due to uncertainties in specific conditions or other factors, and such descriptions are not intended to limit the scope of the invention. Variations and modifications to the embodiments disclosed herein are possible, and various substitutions and equivalents of the components in the embodiments are well known to those skilled in the art. It should be understood by those skilled in the art that the invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of the invention. Other variations and modifications can be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A voltage regulation control circuit for controlling output voltage, characterized in that, The voltage regulation control circuit includes: An operational amplifier circuit has a first input terminal used to obtain a feedback signal characterizing the output voltage, a second input terminal used to obtain a reference voltage, and an output terminal used to couple to the control terminal of the output power transistor to control the output voltage. A current sampling circuit, whose input is coupled to the output power transistor, is used to generate a current sampling signal characterizing the current flowing through the output power transistor; and A compensation circuit, with its first terminal coupled to a current sampling circuit and its second terminal coupled to the output terminal of an operational amplifier circuit, is used to adjust the compensation resistor of the operational amplifier circuit according to the current sampling signal. The compensation resistor value of the operational amplifier circuit is negatively correlated with the current sampling signal. The compensation circuit includes an adjustment circuit and a second capacitor. The first terminal of the adjustment circuit is coupled to the input voltage, and the third terminal of the adjustment circuit is coupled to the output terminal of the current sampling circuit. The first terminal of the second capacitor is coupled to the second terminal of the adjustment circuit, and the second terminal of the second capacitor is coupled to the output terminal of the operational amplifier circuit. The adjustment circuit includes: The eleventh transistor has its first terminal coupled to the input voltage and its second terminal coupled to the first terminal of the second capacitor. The twelfth transistor has its first terminal coupled to the first terminal of the eleventh transistor, and its second terminal coupled to the control terminal of the eleventh transistor and the control terminal of the twelfth transistor, respectively. The thirteenth transistor has its first terminal coupled to the second terminal of the twelfth transistor, and its second terminal coupled to ground; and The fourteenth transistor has its first terminal coupled to the second terminal of the twelfth transistor, its second terminal coupled to ground, and its control terminal coupled to the output terminal of the current sampling circuit.

2. The voltage regulation control circuit as described in claim 1, characterized in that, The voltage regulation control circuit also includes: The level conversion circuit has its input terminal coupled to the output terminal of the operational amplifier circuit, and its output terminal coupled to the control terminal of the output power transistor.

3. The voltage regulation control circuit as described in claim 2, characterized in that, The level conversion circuit includes: The twentieth transistor has its first terminal coupled to an input voltage and its control terminal coupled to a first voltage; and The 21st transistor has its first terminal coupled to the second terminal of the 20th transistor, its control terminal coupled to the output terminal of the operational amplifier circuit, and its second terminal coupled to the fourth resistor; the first terminal of the 21st transistor is used to couple to the control terminal of the output power transistor.

4. A voltage regulation control circuit for controlling the output voltage, characterized in that, The voltage regulation control circuit includes: An operational amplifier circuit has a first input terminal used to obtain a feedback signal characterizing the output voltage, a second input terminal used to obtain a reference voltage, and an output terminal used to couple to the control terminal of the output power transistor to control the output voltage. The current sampling circuit has its input terminal coupled to the output power transistor to generate a current sampling signal characterizing the current flowing through the output power transistor. A compensation circuit, with its first terminal coupled to a current sampling circuit and its second terminal coupled to the output terminal of an operational amplifier circuit, is used to adjust the compensation resistor of the operational amplifier circuit according to the current sampling signal. The compensation resistor value of the operational amplifier circuit is negatively correlated with the current sampling signal. A level conversion circuit, the input of which is coupled to the output of an operational amplifier circuit, and the output of which is coupled to the control terminal of an output power transistor; wherein the level conversion circuit includes: The twentieth transistor has its first terminal coupled to an input voltage and its control terminal coupled to a first voltage; and The 21st transistor has its first terminal coupled to the second terminal of the 20th transistor, its control terminal coupled to the output terminal of the operational amplifier circuit, and its second terminal coupled to the fourth resistor; the first terminal of the 21st transistor is used to couple to the control terminal of the output power transistor.

5. The voltage regulation control circuit as described in claim 1 or 4, characterized in that, The current sampling circuit includes: The sampling resistor has its first terminal coupled to the second terminal of the output power transistor, and its second terminal coupled to ground; and The voltage-to-current conversion circuit has an input terminal coupled to a sampling resistor to obtain a sampling voltage, and an output terminal that outputs a current sampling signal, which is used to generate a current sampling signal based on the sampling voltage.

6. The voltage regulation control circuit as described in claim 1 or 4, characterized in that, The current sampling circuit includes: The fifteenth transistor has its first terminal coupled to the input voltage, and its control terminal coupled to the control terminal of the output power transistor. The sixteenth transistor has its first terminal coupled to the second terminal of the fifteenth transistor; The seventeenth transistor has its first terminal coupled to the second terminal of the output power transistor, and its second terminal coupled to the control terminal of the sixteenth transistor and the control terminal of the seventeenth transistor respectively. The eighteenth transistor has its first terminal coupled to the second terminal of the sixteenth transistor, its second terminal coupled to ground, and its control terminal coupled to both the compensation circuit and the first terminal of the eighteenth transistor; and The nineteenth transistor has its first terminal coupled to the second terminal of the seventeenth transistor, its second terminal coupled to ground, and its control terminal coupled to a second voltage.

7. The voltage regulation control circuit as described in claim 1 or 4, characterized in that, The voltage regulation control circuit further includes a tail current generation circuit, which generates a tail current to provide the operational amplifier circuit with the tail current required for operation. The tail current generation circuit includes: A first current source, whose first terminal is coupled to the input voltage, is used to generate a first current; The ninth transistor has its first terminal and control terminal coupled to the output terminal of the first current source, and its second terminal coupled to ground; and The tenth transistor has its first terminal coupled to an operational amplifier circuit, its second terminal coupled to ground, and its control terminal coupled to the control terminal of the ninth transistor.

8. A low-dropout linear voltage regulator circuit, characterized in that, The low-dropout linear regulator circuit includes a voltage regulation control circuit as described in any one of claims 1-7, wherein the voltage regulation control circuit controls the output power transistor in the low-dropout linear regulator circuit to control the output voltage.

9. A voltage regulation control method for controlling a voltage regulation control circuit as described in claim 1 or 4, characterized in that, The voltage regulation control method includes: The operational amplifier circuit controls the output power transistor to control the output voltage based on the reference voltage and the feedback signal characterizing the output voltage; Generate a current sampling signal that characterizes the current flowing through the output power transistor; The compensation resistor of the operational amplifier circuit is adjusted according to the current sampling signal, and the value of the compensation resistor of the operational amplifier circuit is negatively correlated with the current sampling signal.

10. The voltage regulation control method as described in claim 9, characterized in that, The voltage regulation control circuit includes an operational amplifier circuit and a compensation circuit. The compensation circuit is coupled to the output terminal of the operational amplifier circuit and includes an eleventh transistor. The compensation circuit controls the conduction degree of the eleventh transistor according to the current sampling signal, thereby adjusting the compensation resistor of the operational amplifier circuit.

11. The voltage regulation control method as described in claim 9, characterized in that, The sampling resistor in the voltage regulation control circuit is coupled to the output power transistor. The step of generating a current sampling signal characterizing the current flowing through the output power transistor includes: The sampling voltage is obtained through the sampling resistor, and a current sampling signal is generated based on the sampling voltage. The current sampling signal is a current signal.

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