Quick-start low-power current reference circuit

Abstract

The application provides a current reference circuit, comprising: a reference current generation module configured to charge a first compensation capacitor at a control input node and a second compensation capacitor at a first output node to generate a first reference voltage at the control input node and a second reference voltage at the first output node, respectively; a starting module configured to control the reference current generation module to charge the first compensation capacitor and the second compensation capacitor; an operational amplifier electrically coupled to the reference current generation module and configured to generate an output voltage at a second output node based on the second reference voltage and the first reference voltage; an adjusting module electrically coupled to the first output node and configured to control the first reference voltage and the second reference voltage to be equal; and an output module configured to output a reference current based on the output voltage at the second output node. The current reference circuit has the advantages of ultra-low power consumption and fast starting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits, and in particular to a low-power current reference circuit capable of fast start-up. BACKGROUND

[0002] A current reference module is an important basic module in analog circuits and digital-analog hybrid circuits, and the current reference module needs to provide a reference current that is relatively stable with respect to process, power voltage and temperature. With the development of high integration and low power consumption, the design of the current reference module is more stringent.

[0003] Current reference sources can now be divided into bandgap reference current sources based on a bandgap architecture and current mirror reference current sources based on a current mirror architecture. In ultra-low power circuits with low precision requirements, the reference current usually adopts a current mirror reference current source. The linearity of the reference current of the traditional current mirror architecture is poor. In order to improve the linearity of the reference current of this architecture, the method of adding an operational amplifier is used to reduce the mismatch of the current mirror. The added operational amplifier introduces an additional loop to the traditional current mirror reference current source, and therefore a compensation capacitor needs to be added to ensure the stability of the circuit, but this also leads to the problem of slow start-up of the reference current source. SUMMARY

[0004] The present application provides a current reference circuit which can make the current reference source have the advantages of ultra-low power consumption while also being capable of fast start-up.

[0005] In one aspect of the present application, a current reference circuit is provided. The circuit includes: a reference current generation module configured to charge a first compensation capacitor at a control input node and a second compensation capacitor at a first output node upon power-up to generate a first reference voltage at the control input node and a second reference voltage at the first output node, respectively; a start-up module configured to control the reference current generation module to charge the first compensation capacitor and the second compensation capacitor; an operational amplifier electrically coupled to the first output node and the control input node of the reference current generation module and configured to generate an output voltage at a second output node based on the second reference voltage and the first reference voltage; a regulation module electrically coupled to the first output node and configured to control the first reference voltage and the second reference voltage to tend to be equal; and an output module configured to output a reference current based on the output voltage at the second output node.

[0006] According to the application, the adjusting module is added to the current reference circuit composed of the reference current generating module, the operational amplifier, the starting module and the output module, the first compensation capacitor, the second compensation capacitor and the operational amplifier are introduced to make the stability and linearity of the circuit better, the first reference voltage and the second reference voltage are controlled to be equal by the adjusting module, so as to solve the problem that the first reference voltage and the second reference voltage are not equal due to the existence of the first compensation capacitor and the second compensation capacitor, and the operational amplifier needs to wait for the capacitor to discharge before outputting the first bias voltage in the first state, and then the voltage is output by the second voltage output node of the operational amplifier, and the output module outputs the reference current based on the output voltage at the second output node, so that the low-power current reference source can be quickly started without waiting for the compensation capacitor to discharge. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 The schematic diagram of the current reference circuit according to the embodiment of the application;

[0008] Figure 2 The starting waveform diagram of the current reference circuit at different process corners and different temperatures when the adjusting module is not used;

[0009] Figure 3 The starting waveform diagram of the current reference circuit at different process corners and different temperatures when the adjusting module is used. DETAILED DESCRIPTION

[0010] The technical content, the achieved purposes and effects of the application will be described in detail below in combination with the embodiments and the drawings.

[0011] In the prior art, in order to make the reference current circuit of the low-power current mirror architecture more stable and have better linearity, two compensation capacitors and an operational amplifier are usually introduced into the circuit. In order to make the system stable, the capacitances of the two compensation capacitors are not equal, thereby causing the first reference voltage and the second reference voltage generated by the two compensation capacitors to be not equal, and causing the reference current circuit to need to wait for the capacitors to discharge before being able to output the reference current when the first reference voltage and the second reference voltage are equal, thereby causing the problem of slow starting of the circuit.

[0012] In order to solve at least the above technical problems, the present disclosure provides a low-power current reference circuit which can be quickly started. According to the present disclosure, the adjusting module is added to the low-power, high-linearity reference current source composed of the reference current generating module, the operational amplifier, the starting module and the output module, and the first reference voltage and the second reference voltage output by the reference current generating module are adjusted by the adjusting module so that the two voltages tend to be equal when being input into the operational amplifier. In this way, the reference current circuit according to the embodiment of the present disclosure can overcome the defect of slow starting of the reference current circuit which originally has the advantage of low power consumption, and achieve quick starting.

[0013] Hereinafter, the technical solutions according to the present disclosure will be described with reference to specific embodiments and in conjunction with the accompanying drawings.

[0014] Figure 1 is a schematic diagram illustrating a low-power current reference circuit 100 that can be quickly started according to an embodiment of the present disclosure. Referring to Figure 1 , the circuit 100 includes a reference current generation module 102, a start-up module 104, an operational amplifier 106, a regulation module 108, and an output module 110.

[0015] To facilitate understanding of the operation principle of the circuit, each circuit node in Figure 1 is explained: vbn is a control input node of the reference current generation module 102; vbn2 is at a first output node of the reference current generation module 102; vbp is a first bias input node of the reference current generation module 102; vbp2 is a second bias input node of the operational amplifier 106; vs represents a regulation input node.

[0016] The reference current generation module 102 is configured to charge a first compensation capacitor at the control input node and a second compensation capacitor at the first output node upon power-up, to generate a first reference voltage at the control input node and a second reference voltage at the first output node, respectively.

[0017] The start-up module 104 is configured to control the reference current generation module 102 to charge the first compensation capacitor and the second compensation capacitor.

[0018] The operational amplifier 106 is electrically coupled to the first output node and the control input node of the reference current generation module 102, and is configured to generate an output voltage at a second output node based on the second reference voltage and the first reference voltage.

[0019] The regulation module 108 is electrically coupled to the first output node, and is configured to control the first reference voltage and the second reference voltage to tend to be equal.

[0020] The output module 110 is configured to output a reference current based on the output voltage at the second output node.

[0021] In some embodiments, the regulation module 108 is further configured to cause the second reference voltage at the first output node to tend to be equal to the first reference voltage at the control input node by pulling down the second reference voltage at the first output node. In this way, when facing a situation that the second compensation capacitor is smaller than the first compensation capacitor, the control of the first reference voltage and the second reference voltage to tend to be equal can be effectively and quickly achieved by pulling down the second reference voltage at the first output node.

[0022] In some other embodiments, the adjustment module 108 includes a transistor, a first transmission terminal of the transistor is electrically coupled to the first output node, a control terminal of the transistor is electrically coupled to an adjustment input node charged by an external power source, and a conductive path to which the first transmission terminal of the transistor and a second transmission terminal of the transistor are electrically coupled is used to pull down the second reference voltage at the first output node. In this way, the above-mentioned operation of pulling down the second reference voltage can be realized by controlling the transistor to be turned on through the adjustment input node charged by the external power source, so as to automatically trigger the pulling down operation when the current reference circuit is powered on, and reduce the number of control sources required for the circuit to operate.

[0023] In some embodiments, the operational amplifier 106 is configured to generate an output voltage of a first state at the second output node when the first reference voltage and the second reference voltage are equal, and generate an output voltage of a second state at the second output node when the first reference voltage and the second reference voltage are not equal. The output module 110 is configured to output the desired reference current based on the output voltage of the first state. In this way, the output module 110 is regulated by the input-output control logic of the operational amplifier 106.

[0024] In some embodiments, the second output node is electrically coupled to a first bias input node of the reference current generation module. The reference current generation module is further configured to generate a second reference voltage corresponding to the desired reference current at the first output node based on the first reference voltage at the control input node when the output voltage at the first bias input node is in the first state during the initial charging phase. In this way, a control feedback loop is formed between the second output node of the operational amplifier 106, the first bias input node of the reference current generation module 102, and the first output node of the control input node.

[0025] In some embodiments, the regulation signal output node of the start module 104 is electrically coupled to the first bias input node of the reference current generation module 102 and the second output node of the operational amplifier 106 at the same time. The first output node of the reference current generation module 102 is electrically coupled to the first input terminal of the operational amplifier 106, and the second reference voltage output node of the reference current generation module 102 is electrically coupled to the second input terminal of the operational amplifier 106. In this way, the first bias input node of the current generation module 102 is regulated into the first state by the start module 106 outputting the control signal.

[0026] In some embodiments, the reference current generating module 102 includes a first MOS transistor M1, a second MOS transistor M2, a third MOS transistor M3, a fourth MOS transistor M4, a first compensation capacitor C1, a second compensation capacitor C2, and a first resistor R1. The source of the first MOS transistor M1 and the source of the second MOS transistor M2 are electrically coupled to an external power supply, the gate of the first MOS transistor M1 is electrically coupled to the gate of the second MOS transistor M2, the control signal output node of the starting module 104, and the second output node of the operational amplifier 106. The drain of the first MOS transistor M1 is electrically coupled to the drain and the gate of the third MOS transistor M3, and the first end of the first compensation capacitor C1; the drain of the second MOS transistor M2 is electrically coupled to the drain of the fourth MOS transistor M4 and the first end of the second compensation capacitor C2; the second end of the first compensation capacitor C1 is grounded; the second end of the second compensation capacitor C2 is grounded through the first resistor R1; the gate of the third MOS transistor M3 is electrically coupled to the gate of the fourth MOS transistor M4. The first end of the first compensation capacitor C1 is a control input node, and the first end of the second compensation capacitor C2 is a first output node. In this way, the reference current generating module 102 uses the first MOS transistor M1 and the second MOS transistor M2 as switching elements, controls the conduction of the two through the control signal of the starting module 104, and charges the first compensation capacitor C1 and the second compensation capacitor C2.

[0027] In some embodiments, the operational amplifier 106 includes a fifth MOS transistor M5, a sixth MOS transistor M6, a seventh MOS transistor M7, and an eighth MOS transistor M8. The source of the fifth MOS transistor M5 and the source of the sixth MOS transistor M6 are electrically coupled to an external power supply, the gate and the drain of the fifth MOS transistor M5 and the gate of the sixth MOS transistor M6 are electrically coupled to the second bias input node of the operational amplifier 106. The drain of the fifth MOS transistor M5 is electrically coupled to the drain of the seventh MOS transistor M7, and the drain of the sixth MOS transistor M6 is electrically coupled to the drain of the eighth MOS transistor M8; the gate of the seventh MOS transistor M7 is electrically coupled to the first output node, and the gate of the eighth MOS transistor M8 is electrically coupled to the control input node. The drain of the sixth MOS transistor M6 is electrically coupled to the second output node. In this way, the operational amplifier 106 is composed of the fifth MOS transistor M5, the sixth MOS transistor M6, the seventh MOS transistor M7, and the eighth MOS transistor M8, uses the fifth MOS transistor M5 and the sixth MOS transistor M6 as load tubes, uses the seventh MOS transistor M7 and the eighth MOS transistor M8 as positive and negative amplification input tubes respectively, receives the first reference voltage and the second reference voltage, and outputs the first bias voltage to form a feedback loop, thereby improving the linearity of the current reference circuit and reducing the mismatch problem of the current mirror of the current reference circuit by increasing the operational amplifier 106.

[0028] In some embodiments, the output module 110 comprises a ninth MOS transistor M9. The source of the ninth MOS transistor M9 is electrically coupled with an external power source, the gate of the ninth MOS transistor M9 is electrically coupled with the second output node, and the drain of the ninth MOS transistor outputs a reference current. In this way, the on-off state of the ninth MOS transistor M9 is controlled by the signal outputted by the second output node of the operational amplifier 106.

[0029] In some embodiments, the start module 104 comprises a third capacitor C3, a tenth MOS transistor M10, an eleventh MOS transistor M11, a twelfth MOS transistor M12, a thirteenth MOS transistor M13, and a fourteenth MOS transistor M14. The first end of the third capacitor C3 and the source of the tenth MOS transistor M10 are both electrically coupled with an external power source, the gate and the drain of the tenth MOS transistor M10 are both electrically coupled with the source of the eleventh MOS transistor M11, the gate and the drain of the eleventh MOS transistor M11 are both electrically coupled with the source of the twelfth MOS transistor M12, the gate and the drain of the twelfth MOS transistor M12 are both electrically coupled with the drain of the thirteenth MOS transistor M13. The second end of the third capacitor C3 is electrically coupled with the drain of the thirteenth MOS transistor M13 and the gate of the fourteenth MOS transistor M14 at the regulating input node, the gate of the thirteenth MOS transistor M13 is electrically coupled with the control input node, and the drain of the fourteenth MOS transistor M14 is electrically coupled with the second output node. The source of the thirteenth MOS transistor M13 and the source of the fourteenth MOS transistor M14 are both grounded. In this way, when powered on, the gate voltage of the fourteenth MOS transistor M14 is pulled high by the third capacitor C3, and the first bias voltage is pulled low, so that the first MOS transistor M1 and the second MOS transistor M2 are turned on, and the initial start is completed.

[0030] In some embodiments, the regulating module 108 comprises a fifteenth MOS transistor M15. The drain of the fifteenth MOS transistor M15 is electrically coupled with the first output node, the gate of the fifteenth MOS transistor M15 is electrically coupled with the regulating input node, and the source of the fifteenth MOS transistor M15 is electrically coupled with the second bias input node. In this way, the regulating module 108 adopts the fifteenth MOS transistor M15 to form a "virtual short" between the node of the second reference voltage and the second bias input node after the fifteenth MOS transistor M15 is turned on, so as to adjust the second reference voltage to a state equivalent to the first reference voltage, which has a simple structure and is convenient to control.

[0031] Reference Figure 1As shown, the composition of the current reference circuit includes: M1-M4 and R1 constitute a reference current generation module, i.e. the core part of the circuit. M5-M8 constitute an operational amplifier part for improving the linearity of the reference current, M5 and M6 are load tubes, M7 is a positive input amplifying tube of the operational amplifier, and M8 is a negative input amplifying tube of the operational amplifier. M9 is an output module part of the reference current source, and the load connected to the drain of M9 can provide the reference current for the load. M10-M14 and C3 constitute a starting circuit of the reference current source.

[0032] In the present application, M15 is a regulating module added by the present application to accelerate the starting speed of the reference current source circuit. M15 can also be replaced by other types of tubes, and if a P-type tube is used, the control signal thereof is opposite to that of an N-type tube. It is necessary to ensure that M15 is turned on when the circuit starts and is turned off when the circuit starts.

[0033] In addition, compensation capacitors C1 and C2 are added to stabilize the system. The capacitance of C1 is about four times that of C2. In the structure in which the operational amplifier is added to improve the linearity of the reference current source, the stability of the circuit needs to be compensated, and the compensation capacitor C1 is greater than C2, and the specific multiple is different for different processes and design sizes.

[0034] It is worth noting that the positive feedback loop refers to the fact that when a certain direction of jitter occurs at the input end, the jitter in the direction of the input end will increase after passing through the positive feedback loop, i.e. the jitter will be strengthened. The negative feedback loop refers to the fact that when a certain direction of jitter occurs at the input end, the jitter in the direction of the input end will be weakened after passing through the negative feedback loop. The gain refers to the intensity of the input end jitter after passing through the loop.

[0035] In combination Figure 1 As shown, each vs node, each vbn node, each vbp node, and each vbp2 node are electrically coupled through metal wiring. Based on this, in the present application, the negative feedback loop is vbp→vbn2→vbp2→vbp, and the positive feedback loop is vbp→vbn→vbn2→vbp2→vbp and vbp→vbn→vbp. Any node in the loop can be used as a feedback input end.

[0036] In order to clearly show the role of the regulating module, the use process of the low-power current reference circuit capable of being quickly started according to the present application is described in the following cases:

[0037] 1. The case without M15 in the circuit

[0038] When the circuit is powered on, there is no current in the reference current source circuit, the gate of M13 is low, and node vs is pulled high by capacitor C3. At the moment when vs is pulled high, vbp is pulled low, and vbn and vbn2 start to charge. Due to the compensation capacitor C1 > C2, the initial voltage of node vbn2 is much larger than that of vbn1. Since the loop in which vbn2 is located is a negative feedback loop, the discharging speed of vbn2 is very slow, so there is still a large voltage difference between nodes vbn2 and vbn after vs becomes low, that is, the positive input voltage of the operational amplifier is greater than the negative input voltage. Therefore, after vs becomes low, the operational amplifier pulls vbp back to high, and the initial current of the circuit becomes very small. At this time, it is necessary to wait for vbn2 to slowly discharge before re-entering positive feedback start, and the start time is very long.

[0039] 2. Circuit with M15

[0040] When the circuit is first powered on, there is no current in the circuit, vs is high, vbp is pulled low, and vbn and vbn2 nodes start to charge. Due to the compensation capacitor C1 > C2, the initial voltage of node vbn2 is much larger than that of vbn1. However, due to the presence of M15, vbn2 and vbp2 are in a virtual short state when vs is high. At this time, the loop in which vbn2 is located changes from a negative feedback loop to a positive feedback loop, so vbn2 can quickly drop to a voltage value comparable to vbn, ensuring that the voltage difference between vbn and vbn2 is small when vs becomes low, thereby ensuring that vbp will not be pulled high when vs becomes low. Thus, the circuit does not need to wait for vbn2 to slowly discharge before re-entering positive feedback start, and the start time is shortened.

[0041] During the above operation, the circuit can normally pass through negative feedback to quickly lock the correct static operating point when vs is low. At this time, it should be noted that the size of M14 cannot be too large to ensure that the charging current of capacitors C1 and C2 is not too large when vs becomes high, ensuring that nodes vbn and vbn2 have a small initial voltage difference. Moreover, when the circuit is stable, the voltage of vbn is equal to that of vbn2 due to the clamping action of the operational amplifier, so the current flowing through M7 and the current flowing through M3 are in a size ratio relationship. Therefore, vbp2 can also be used as the first bias voltage of the reference current source.

[0042] Combining Figure 2 and Figure 3 as shown, Figure 2 and Figure 3 are the start waveforms of the fast start ultra-low power current reference circuit before and after optimization under different corners and temperatures. From Figure 2It can be seen that, before optimization, the starting speed of the ultra-low power current reference circuit at some temperature in some corner is up to 1.8ms, from Figure 3 It can be seen that the starting time of the optimized current reference circuit is within 300us, effectively improving the starting speed of the circuit.

[0043] In summary, the current reference circuit provided by the application adds an adjusting module to the low-power circuit composed of a reference current generation module, an operational amplifier, a starting module and an output module, introduces a first compensation capacitor, a second compensation capacitor and an operational amplifier to make the stability and linearity of the circuit better, and the existence of the first compensation capacitor and the second compensation capacitor will make the first reference voltage and the second reference voltage not equal, so that the operational amplifier needs to wait for the capacitor to discharge before outputting the first bias voltage in the first state, that is, the reference current generation module can output the reference current, the first reference voltage and the second reference voltage are controlled to be equal by the adjusting module to make up for the above defects, so that the low-power current reference source can start quickly without waiting for the compensation capacitor to discharge, and the linkage between each control signal in the circuit is used, the number of digital control signal sources required by the circuit is reduced, and the cost of the circuit is reduced.

[0044] The above is only an embodiment of the application, and does not limit the patent range of the application, any equivalent transformation or direct or indirect application in related technical fields using the content of the specification and drawings of the application are also included in the patent protection range of the application.

Claims

1. A current reference circuit, characterized in that, include: The reference current generation module is configured to charge the first compensation capacitor at the control input node and the second compensation capacitor at the first output node when powered on, so as to generate a first reference voltage at the control input node and a second reference voltage at the first output node, respectively. The startup module is configured to control the reference current generation module to charge the first compensation capacitor and the second compensation capacitor; An operational amplifier is electrically coupled to the first output node and the control input node of the reference current generation module, and is configured to generate an output voltage at the second output node based on the second reference voltage and the first reference voltage; The adjustment module is electrically coupled to the first output node and configured to control the first reference voltage and the second reference voltage to tend to be equal; as well as The output module is configured to output a reference current based on the output voltage at the second output node. The adjustment module is configured to make the second reference voltage at the first output node approximately equal to the first reference voltage at the control input node by pulling down the second reference voltage at the first output node.

2. The circuit according to claim 1, characterized in that, The regulation module includes a transistor, a first transmission terminal of which is electrically coupled to the first output node, and a control terminal of which is electrically coupled to a regulation input node charged by an external power source. The conductive path to which the first transmission terminal and the second transmission terminal of the transistor are electrically coupled is used to pull down the second reference voltage at the first output node.

3. The circuit according to claim 1, characterized in that, The operational amplifier is configured to generate the output voltage in a first state at the second output node when the first reference voltage and the second reference voltage are equal, and to generate the output voltage in a second state at the second output node when the first reference voltage and the second reference voltage are not equal. The output module is configured to output a desired reference current based on the output voltage of the first state.

4. The circuit according to claim 3, characterized in that, The second output node is electrically coupled to the first bias input node of the reference current generation module; The reference current generation module is configured to generate a second reference voltage at the first output node corresponding to the desired reference current based on the first reference voltage at the control input node when the output voltage at the first bias input node is in the first state during the initial charging phase.

5. The circuit according to claim 1, characterized in that, The control signal output node of the startup module is electrically coupled to both the first bias input node of the reference current generation module and the second output node of the operational amplifier. The first output node of the reference current generation module is electrically coupled to the first input terminal of the operational amplifier, and the control input node of the reference current generation module is electrically coupled to the second input terminal of the operational amplifier.

6. The circuit according to claim 1, characterized in that, The reference current generation module includes a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a first compensation capacitor, a second compensation capacitor, and a first resistor; The source of the first MOS transistor and the source of the second MOS transistor are both electrically coupled to an external power supply. The gate of the first MOS transistor is simultaneously electrically coupled to the gate of the second MOS transistor, the control signal output node of the startup module, and the second output node of the operational amplifier. The drain of the first MOS transistor is electrically coupled to the drain and gate of the third MOS transistor and the first terminal of the first compensation capacitor. The drain of the second MOS transistor is electrically coupled to the drain of the fourth MOS transistor and the first terminal of the second compensation capacitor. The second terminal of the first compensation capacitor is grounded, and the second terminal of the second compensation capacitor is grounded through the first resistor. The gate of the third MOS transistor is electrically coupled to the gate of the fourth MOS transistor; as well as The first end of the first compensation capacitor is the control input node, and the first end of the second compensation capacitor is the first output node.

7. The circuit according to claim 2, characterized in that, The operational amplifier includes a fifth MOSFET, a sixth MOSFET, a seventh MOSFET, and an eighth MOSFET; The source of the fifth MOS transistor and the source of the sixth MOS transistor are both electrically coupled to an external power supply, and the gate and drain of the fifth MOS transistor and the gate of the sixth MOS transistor are all electrically coupled to the second bias input node of the operational amplifier. The drain of the fifth MOS transistor is electrically coupled to the drain of the seventh MOS transistor, the drain of the sixth MOS transistor is electrically coupled to the drain of the eighth MOS transistor, the gate of the seventh MOS transistor is electrically coupled to the first output node, and the gate of the eighth MOS transistor is electrically coupled to the control input node; and The drain of the six MOS transistors is electrically coupled to the second output node.

8. The circuit according to claim 1, characterized in that, The output module includes a ninth MOS transistor; The source of the ninth MOS transistor is electrically coupled to an external power supply, the gate of the ninth MOS transistor is electrically coupled to the second output node, and the drain of the ninth MOS transistor outputs the reference current.

9. The circuit according to claim 7, characterized in that, The startup module includes a third capacitor, a tenth MOSFET, an eleventh MOSFET, a twelfth MOSFET, a thirteenth MOSFET, and a fourteenth MOSFET; The first terminal of the third capacitor and the source of the tenth MOS transistor are both electrically coupled to an external power supply. The gate and drain of the tenth MOS transistor are both electrically coupled to the source of the eleventh MOS transistor. The gate and drain of the eleventh MOS transistor are both electrically coupled to the source of the twelfth MOS transistor. The gate and drain of the twelfth MOS transistor are both electrically coupled to the drain of the thirteenth MOS transistor. The second terminal of the third capacitor is electrically coupled at the adjustment input node to both the drain of the thirteenth MOS transistor and the gate of the fourteenth MOS transistor. The gate of the thirteenth MOS transistor is electrically coupled to the control input node, and the drain of the fourteenth MOS transistor is electrically coupled to the second output node. The source of both the thirteenth MOS transistor and the fourteenth MOS transistor are grounded.

10. The circuit according to claim 9, characterized in that, The adjustment module includes a fifteenth MOS transistor; The drain of the fifteenth MOS transistor is electrically coupled to the first output node, the gate of the fifteenth MOS transistor is electrically coupled to the adjustment input node, and the source of the fifteenth MOS transistor is electrically coupled to the second bias input node.

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