Start circuit and low-power-consumption reference source

Abstract

The present application discloses a start circuit and a low-power-consumption reference source. The start circuit is connected to a reference circuit, and the start circuit comprises: a coupling boosting module connected to a first node and configured to couple and boost a voltage of the first node; a start control module connected to the first node and configured to adjust the voltage of the first node on the basis of a bandgap reference voltage of the reference circuit; a current limiting module connected to the coupling boosting module and configured to adjust an output current of the coupling boosting module on the basis of the bandgap reference voltage of the reference circuit; and a conversion module configured to adjust a voltage of a second node on the basis of the voltage of the first node; wherein the current limiting module is further configured to adjust the output current of the coupling boosting module on the basis of the voltage of the second node.

Description

Startup circuit and low power reference source

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application 202311811700.4, filed on December 26, 2023, entitled “Start-up circuit and low-power reference source,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of electronic circuits, and in particular relates to a startup circuit and a low-power reference source. Background Art

[0004] Bandgap references are typically used to provide a stable reference voltage / current. To maintain the reference circuit in a steady-state operating point, a startup circuit is typically included within the bandgap reference. This circuit provides an excitation voltage / current to the reference circuit upon power-up, allowing it to quickly reach a steady-state operating point and preventing it from entering a degenerate state. Once the reference circuit enters normal operation, the startup circuit gradually shuts down.

[0005] At present, the startup circuit in the related art is usually composed of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other types of transistors. The startup circuit can control the on-state of the MOSFET according to the bandgap reference voltage or bias signal output by the reference circuit. However, when the reference circuit enters the normal operating state, the voltage difference between the bandgap reference voltage or bias signal received by the startup circuit and the power supply signal is large, so that the MOSFET remains in the on-state due to the gate-source voltage difference reaching the on-threshold. The current flowing through the MOSFET in the on-state is large, which will cause the power consumption of the startup circuit to increase when the reference circuit is in the normal operating state. In addition, in a high temperature environment, the on-threshold of the MOSFET will be further reduced, thereby causing the power consumption of the startup circuit to further increase. Summary of the Invention

[0006] The embodiments of the present application provide a startup circuit and a low-power reference source, which can solve the technical problem in the related art that the startup circuit consumes a large amount of power when the reference circuit operates normally.

[0007] In a first aspect, an embodiment of the present application provides a startup circuit, wherein the startup circuit is connected to a reference circuit; the startup circuit includes:

[0008] A coupling boost module, connected to the first node, for coupling and boosting the voltage of the first node; wherein the first node is used to provide an excitation voltage for the startup switch, and the startup switch is used to provide a startup current for the reference circuit when it is turned on;

[0009] a startup control module connected to the first node and configured to adjust the voltage of the first node according to a bandgap reference voltage of a reference circuit;

[0010] A current limiting module is connected to the coupling boost module and is used to adjust the output current of the coupling boost module according to the bandgap reference voltage of the reference circuit;

[0011] A conversion module is connected between the first node and the second node, and is used to adjust the voltage of the second node according to the voltage of the first node; wherein the current limiting module is connected to the second node, and the current limiting module is also used to adjust the output current of the coupled boost module according to the voltage of the second node.

[0012] In some embodiments, the startup control module includes:

[0013] The first transistor is connected between the first node and the ground terminal. The gate of the first transistor is connected to the reference circuit. The bandgap reference voltage of the reference circuit is used to adjust the conduction state of the first transistor.

[0014] In some embodiments, the coupled boost module includes:

[0015] A current source is connected between the first node and the power supply terminal, and a control terminal of the current source is connected to the current limiting module;

[0016] The coupling unit is connected between the first node and the power supply end, and is used to couple and boost the voltage of the first node when the power supply end provides the power voltage.

[0017] In some embodiments, the coupling unit includes a first capacitor, and the current source includes:

[0018] a second transistor connected between the first node and a power supply terminal;

[0019] The third transistor is connected between the current limiting module and the power supply end. The gate of the third transistor is connected to the gate of the second transistor. The gate of the third transistor is also connected to the current limiting module.

[0020] In some embodiments, the current limiting module includes:

[0021] a fourth transistor connected between the coupled boost module and the third node, wherein a gate of the fourth transistor is connected to a reference circuit; a bandgap reference voltage of the reference circuit is used to adjust a conduction state of the fourth transistor;

[0022] The fifth transistor is connected between the third node and the ground terminal, and the gate of the fifth transistor is connected to the second node; the voltage of the second node is used to adjust the conduction state of the fifth transistor.

[0023] In some embodiments, the conversion module includes:

[0024] a first inverter and a second inverter, the first inverter being connected between the first node and the second inverter, and the second inverter being connected between the first inverter and the second node;

[0025] The second capacitor is connected between the power supply terminal and the second node.

[0026] In some embodiments, the startup circuit further comprises:

[0027] The indication signal module is connected to the second node and is used to generate an indication signal according to the voltage of the second node.

[0028] In some embodiments, the startup circuit further includes a voltage divider module, and the voltage divider module is provided in at least one of the following:

[0029] Between the current limiting module and the coupled boost module;

[0030] Between the start control module and the ground terminal;

[0031] Coupling between the boost module and the power supply terminal;

[0032] Between the conversion module and the power supply terminal; and,

[0033] Between the conversion module and the ground terminal.

[0034] In some embodiments, the voltage divider module includes a voltage divider MOSFET, and a gate and a drain of the voltage divider MOSFET are connected.

[0035] In a second aspect, an embodiment of the present application provides a low-power reference source, comprising a reference circuit and the startup circuit of the first aspect.

[0036] Compared to related technologies, the startup circuit and low-power reference source provided in the embodiments of the present application utilize a coupled boost module to couple and boost the voltage at the first node during power-up. When the voltage at the first node is raised, it provides an excitation voltage for the reference circuit, thereby starting the reference circuit. During startup, the bandgap reference voltage output by the reference circuit gradually increases. The startup control module lowers the voltage at the first node based on the increasing bandgap reference voltage. When the bandgap reference voltage stabilizes, the voltage at the first node is lowered to a point where it no longer provides excitation for the reference circuit, thereby shutting down the startup circuit. Both the bandgap reference voltage output by the reference circuit and the voltage at the second node generated based on the voltage at the first node can adjust the current limiting effect of the current limiting module. When the bandgap reference voltage is low, the current limiting effect of the current limiting module is weak, and the coupled boost module can quickly raise the voltage at the first node, enabling rapid startup of the startup circuit. As the bandgap reference voltage gradually increases, the current limiting effect of the current limiting module also gradually increases, thereby reducing the power consumption of the startup circuit itself. After the startup circuit completes startup, the voltage of the second node that changes with the voltage of the first node can also increase the current limiting effect of the current limiting module, reduce the power consumption of the startup circuit itself, and ensure that the startup circuit can be completely shut down and exit, preventing the startup circuit from affecting the normal operation of the reference circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] FIG1 is a schematic diagram of the circuit structure of a startup circuit provided in one embodiment of the present application;

[0039] FIG2 is a schematic diagram of the circuit structure of a startup circuit provided in another embodiment of the present application;

[0040] FIG3 is a schematic diagram of the circuit structure of a startup circuit provided in yet another embodiment of the present application;

[0041] FIG4 is a schematic diagram of the circuit structure of a startup circuit provided in yet another embodiment of the present application;

[0042] FIG5 is a schematic diagram of the circuit structure of a startup circuit provided in yet another embodiment of the present application;

[0043] FIG6 is a schematic diagram of the circuit structure of a startup circuit provided in yet another embodiment of the present application.

[0044] In the accompanying drawings: 10, coupling boost module; 11, current source; 12, coupling unit; 20, start-up control module; 30, current limiting module; 40, conversion module; 2, reference circuit; VBG, bandgap reference voltage; 41, first inverter; 42, second inverter; 50, indication signal module; 60, voltage divider module; N1, first node; N2, second node; N3, third node; C1, first capacitor; C2, second capacitor; MO, start-up switch; M1, first transistor; M2, second transistor; M3, third transistor; M4, fourth transistor; M5, fifth transistor. DETAILED DESCRIPTION

[0045] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0046] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0047] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The embodiments will be described in detail below with reference to the accompanying drawings.

[0048] Bandgap references are typically used to provide a stable reference voltage / current. To maintain the reference circuit in a steady-state operating point, a startup circuit is typically included within the bandgap reference. This circuit provides an excitation voltage / current to the reference circuit upon power-up, allowing it to quickly reach a steady-state operating point and preventing it from entering a degenerate state. Once the reference circuit enters normal operation, the startup circuit gradually shuts down.

[0049] At present, the startup circuit in the related art is usually composed of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other types of transistors. The startup circuit can control the on-state of the MOSFET according to the bandgap reference voltage or bias signal output by the reference circuit. However, when the reference circuit enters the normal operating state, the voltage difference between the bandgap reference voltage or bias signal received by the startup circuit and the power supply signal is large, so that the MOSFET remains in the on-state due to the gate-source voltage difference reaching the on-threshold. The current flowing through the MOSFET in the on-state is large, which will cause the power consumption of the startup circuit to increase when the reference circuit is in the normal operating state. In addition, in a high temperature environment, the on-threshold of the MOSFET will be further reduced, thereby causing the power consumption of the startup circuit to further increase.

[0050] In order to solve the above technical problems, the embodiments of the present application provide a startup circuit and a low-power reference source.

[0051] FIG1 shows a schematic diagram of a startup circuit according to an embodiment of the present invention. The startup circuit can be connected to a reference circuit 2. The startup circuit includes a coupled boost module 10, a startup control module 20, a current limiting module 30, and a conversion module 40.

[0052] The coupled boost module 10 is connected to the first node N1 and can couple and boost the voltage of the first node N1 to raise the voltage of the first node N1. The voltage of the first node N1 can serve as an excitation voltage for the startup switch M0. When the excitation voltage reaches the conduction threshold of the startup switch M0, the startup switch M0 turns on and provides a startup current to the reference circuit 2. Raising the voltage of the first node N1 is equivalent to injecting a startup current into the reference circuit 2, thereby starting the reference circuit 2.

[0053] The coupling and boosting module 10 couples and boosts the voltage of the first node N1 . This may be when the startup circuit is powered on, the coupling and boosting module 10 couples and boosts the voltage of the first node N1 according to the power supply voltage after power-on.

[0054] The startup control module 20 is connected to the first node N1. The startup control module 20 can be connected to the reference circuit 2 and receive a bandgap reference voltage VBG provided by the reference circuit 2. When the reference circuit 2 is not in operation, the bandgap reference voltage VBG is low. As the voltage at the first node N1 gradually increases, acting as the excitation voltage for the startup switch M0, the startup switch M0 gradually turns on, and the bandgap reference voltage VBG provided by the reference circuit 2 during the startup process also gradually increases.

[0055] As the bandgap reference voltage VBG increases, the startup control module 20 can adjust the voltage at the first node N1 based on the increasing bandgap reference voltage VBG. For example, the startup control module 20 can lower the voltage at the first node N1 in response to the increasing bandgap reference voltage VBG. When the bandgap reference voltage VBG provided by the reference circuit 2 reaches a stable state, the startup control module 20 can lower the voltage at the first node N1 to below the turn-on voltage of the startup switch M0, causing the startup switch M0 to switch from the on state to the off state. This is equivalent to the startup circuit ceasing to inject startup current into the reference circuit 2, i.e., shutting down the startup circuit. Accordingly, to accommodate the disconnection of the startup switch M0 when the voltage at the first node N1 is a low-level signal, the startup switch M0 can be an N-type transistor.

[0056] The current limiting module 30 can be connected to the coupled boost module 10. The current limiting module 30 can also be connected to the reference circuit 2 and receive the bandgap reference voltage VBG provided by the reference circuit 2. The current limiting module 30 can adjust the output current of the coupled boost module 10 according to the bandgap reference voltage VBG provided by the reference circuit 2.

[0057] When the reference circuit 2 is not in operation, the bandgap reference voltage VBG is low, and the current limiting module 30 has a relatively low current limiting effect on the output current of the coupled boost module 10. The coupled boost module 10 can quickly increase the voltage of the first node N1 through a relatively large output current, thereby improving the startup speed of the startup circuit.

[0058] As the bandgap reference voltage VBG provided by the reference circuit 2 gradually increases, the current-limiting module 30 gradually increases its current-limiting effect on the output current of the coupled boost module 10. Specifically, as the bandgap reference voltage VBG provided by the reference circuit 2 gradually increases, the current-limiting module 30 can function to limit the output current of the coupled boost module 10. When the output current of the coupled boost module 10 is limited, the startup circuit's operating power consumption is reduced by limiting the current magnitude.

[0059] When the bandgap reference voltage VBG output by the reference circuit 2 is low, the current limiting effect of the current limiting module 30 is relatively small. At this time, the coupled boost module 10 can quickly raise the voltage of the first node N1 through a large output current, thereby improving the startup speed of the startup circuit. When the reference circuit 2 outputs a stable bandgap reference voltage VBG, the current limiting module 30 can reduce the power consumption of the startup circuit by limiting the output current of the coupled boost module 10.

[0060] The conversion module 40 is connected between the first node N1 and the second node N2. The conversion module 40 can adjust the voltage of the second node N2 according to the voltage of the first node N1. The second node N2 is connected to the current limiting module 30, which can adjust the output current of the coupled boost module 10 according to the voltage of the second node N2.

[0061] The conversion module 40 can obtain the voltage of the first node N1 and adjust the voltage of the second node N2 according to the voltage of the first node N1. For example, the conversion module 40 can increase the voltage of the second node N2 when the voltage of the first node N1 increases, and decrease the voltage of the second node N2 when the voltage of the first node N1 decreases; or, the conversion module 40 can decrease the voltage of the second node N2 when the voltage of the first node N1 increases, and increase the voltage of the second node N2 when the voltage of the first node N1 decreases.

[0062] The current limiting module 30 can obtain the voltage of the second node N2 and adjust the output current of the coupled boost module 10 according to the voltage of the second node N2. That is, the current limiting module 30 can adjust the degree of current limiting according to the voltage of the second node N2, in addition to adjusting the degree of current limiting according to the bandgap reference voltage VBG of the reference circuit 2.

[0063] It should be noted that the current limiting module 30 adjusts the current limiting strength of the output current of the coupled boost module 10 based on the voltage of the second node N2, and can be analyzed based on the voltage of the first node N1. For example, as the bandgap reference voltage VBG provided by the reference circuit 2 increases, the voltage of the first node N1 gradually decreases. In this case, the current limiting module 30 should gradually increase the current limiting strength of the output current of the coupled boost module 10 in response to the voltage of the second node N2. If the voltage of the second node N2 decreases as the voltage of the first node N1 decreases, the current limiting module 30 may gradually increase the current limiting effect as the voltage of the second node N2 decreases. If the voltage of the second node N2 increases as the voltage of the first node N1 decreases, the current limiting module 30 may gradually increase the current limiting effect as the voltage of the second node N2 increases.

[0064] As the bandgap reference voltage VBG increases, the voltage at the first node N1 gradually decreases. The increased bandgap reference voltage VBG can drive the current limiting module 30 to enhance the current limiting effect on the coupled boost module 10. The conversion module 40 can adjust the voltage at the second node N2 using the reduced first voltage, and use the voltage at the second node N2 to drive the current limiting module 30 to enhance the current limiting effect on the coupled boost module 10. In other words, both the bandgap reference voltage VBG and the voltage at the second node N2 can enhance the current limiting function of the current limiting module 30, thereby ensuring that the current limiting module 30 can limit the loop current to reduce the power consumption of the startup circuit, and can also ensure that the startup circuit can be shut down after startup is completed, preventing the startup circuit from affecting the normal operation of the reference circuit 2.

[0065] In this embodiment, by providing a coupling boost module 10, the voltage at the first node N1 can be coupled and boosted during power-up. When the voltage at the first node N1 is raised, it can provide an excitation voltage for the reference circuit 2, thereby starting the reference circuit 2. During the startup process, the bandgap reference voltage VBG output by the reference circuit 2 gradually increases. The startup control module 20 can lower the voltage at the first node N1 based on the gradually increasing bandgap reference voltage VBG. When the bandgap reference voltage VBG stabilizes, the voltage at the first node N1 is lowered to a level that no longer provides excitation for the reference circuit 2, thereby shutting down the startup circuit. The bandgap reference voltage VBG output by the reference circuit 2 and the voltage at the second node N2 generated based on the voltage at the first node N1 can both adjust the current limiting function of the current limiting module 30. When the bandgap reference voltage VBG is low, the current limiting effect of the current limiting module 30 is relatively small, and the coupled boost module 10 can quickly increase the voltage of the first node N1, thereby achieving rapid startup of the startup circuit. As the bandgap reference voltage VBG gradually increases, the current limiting effect of the current limiting module 30 also gradually increases, thereby reducing the power consumption of the startup circuit. After the startup circuit completes startup, the voltage of the second node N2, which changes with the voltage of the first node N1, can also increase the current limiting effect of the current limiting module 30, reducing the power consumption of the startup circuit and ensuring that the startup circuit can be completely shut down and exit, preventing the startup circuit from affecting the normal operation of the reference circuit 2.

[0066] Referring to FIG. 2 , in some embodiments, the startup control module 20 may include a first transistor M1. The first transistor may be connected between a first node N1 and a ground terminal. The gate of the first transistor M1 may be connected to a reference circuit 2. The reference circuit 2 provides a bandgap reference voltage VBG that can adjust the conduction state of the first transistor M1.

[0067] When the startup circuit is not powered on, the voltage of the first node N1 is lower than the turn-on threshold voltage of the startup switch M0 . At this time, the reference circuit 2 is not working, and the bandgap reference voltage VBG provided by the reference circuit 2 is low.

[0068] The first transistor M1 can be an N-type transistor, such as an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other transistor that turns on in response to a high-level signal. When the bandgap reference voltage VBG is low, the first transistor M1 is in an off state, and the first node N1 is disconnected from the ground terminal.

[0069] When the first node N1 is disconnected from the ground, the first node N1 can be regarded as a high-resistance state relative to the ground. When the startup circuit is powered on, the coupling boost module 10 can couple and boost the voltage of the first node N1, so that the voltage of the first node N1 gradually increases.

[0070] Since the voltage at the first node N1 can serve as the excitation voltage for the reference circuit 2, after the voltage at the first node N1 rises to the turn-on threshold voltage of the start-up switch M0, the start-up switch M0 is turned on, injecting a start-up current into the reference circuit 2. At this point, the reference circuit 2 begins to operate, and during the operation of the reference circuit 2, the bandgap reference voltage VBG output by the reference circuit 2 gradually increases.

[0071] Taking the first transistor M1 as an N-type transistor as an example, as the bandgap reference voltage VBG gradually increases, the conduction amplitude of the first transistor M1 gradually increases, causing the current flowing through the first transistor M1 to gradually increase. Because the first transistor M1 is connected between the ground terminal and the first node N1, the first transistor M1 that gradually turns on can pull down the potential of the first node N1. In other words, as the bandgap reference voltage VBG increases, the first transistor M1 can pull down the potential of the first node N1, causing the potential of the first node N1 to drop below the conduction threshold voltage of the startup switch M0. At this time, the startup switch M0 is turned off, which is equivalent to stopping the startup circuit and exiting the startup process.

[0072] Continuing to refer to FIG. 2 , in some embodiments, the coupling boost module 10 may include a current source 11 and a coupling unit 12 .

[0073] The current source 11 may be connected between the first node N1 and the power supply terminal VCC, and a control terminal of the current source 11 may be connected to the current limiting module 30 .

[0074] The coupling unit 12 may be connected between the first node N1 and the power supply terminal VCC. When the startup circuit is powered on, the power supply terminal VCC may provide a power supply voltage, and the coupling unit 12 may couple and boost the voltage of the first node N1.

[0075] One end of the coupling unit 12 is connected to the power supply terminal VCC, and the other end is connected to the first node N1. When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage. Since the voltage at both ends of the coupling unit 12 cannot change suddenly, it will correspondingly pull up the potential of the first node N1, thereby coupling and boosting the voltage of the first node N1.

[0076] After the voltage at first node N1 increases, reference circuit 2 gradually starts up, receiving the increased voltage at first node N1 as an incentive, causing the bandgap reference voltage VBG to gradually increase. Current limiting module 30 limits the current of current source 11 based on the increasing bandgap reference voltage VBG. As the current at the control terminal of current source 11 gradually decreases, it also limits the loop current between power supply terminal VCC and first node N1, thereby reducing the power consumption of the startup circuit itself by lowering the loop current. Through current source 11 and coupling unit 12, coupled boost module 10 can achieve both DC coupling and AC coupling at first node N1.

[0077] In some embodiments, the coupling unit 12 may include a first capacitor C1 , and the current source 11 may include a second transistor M2 and a third transistor M3 .

[0078] The two ends of the first capacitor C1 are connected to the power supply terminal VCC and the first node N1 respectively. When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage. The first capacitor C1 can couple and raise the potential of the first node N1 to achieve coupled voltage boosting of the first node N1.

[0079] The second transistor M2 can be connected between the first node N1 and the power supply terminal VCC, and the third transistor M3 can be connected between the current limiting module 30 and the power supply terminal VCC. The gate of the second transistor M2 is connected to the gate of the third transistor M3, and the gate of the third transistor M3 can also be connected to the current limiting module 30.

[0080] The second transistor M2 and the third transistor M3 can form a current mirror, i.e., a mirrored constant current source. The current in the loop where the current limiting module 30 is located is the input current, and the current in the loop where the first node N1 is located is the output current. Because the input-to-output current transfer ratio of the current mirror is equal to 1, the current limiting module 30 can correspondingly limit the current in the loop where the first node N1 is located by limiting the current in its loop.

[0081] When the current limiting module 30 limits the current in the loop containing the first node N1, the current between the power supply terminal VCC and the first node N1 gradually decreases, weakening the power supply voltage's ability to pull up the potential of the first node N1. This will cause the potential of the first node N1 to gradually decrease. Furthermore, as the bandgap reference voltage VBG gradually increases, the gradually turned-on first transistor M1 will increase the ground terminal's ability to pull down the potential of the first node N1.

[0082] When the pull-up capability weakens and the pull-down capability strengthens, the potential of the first node N1 gradually decreases. That is, the current limiting module 30 increases the current limiting function in response to the bandgap reference voltage VBG, thereby lowering the potential of the first node N1. The first transistor M1 of the startup control module 20 gradually turns on in response to the bandgap reference voltage VBG, thereby also lowering the potential of the first node N1.

[0083] 3 , in some embodiments, the current limiting module 30 may include a fourth transistor M4 and a fifth transistor M5. The fourth transistor M4 is connected between the coupled boost module 10 and the third node N3, and the gate of the fourth transistor M4 is connected to the reference circuit 2. The fifth transistor M5 is connected between the third node N3 and the ground terminal, and the gate of the fifth transistor M5 is connected to the second node N2.

[0084] The bandgap reference voltage VBG output by the reference circuit 2 can adjust the conduction state of the fourth transistor M4. As the bandgap reference voltage VBG gradually increases, the fourth transistor M4 operates in a saturation region, and the current flowing through the fourth transistor M4 is negatively correlated with the gate-source voltage difference. Because the gate voltage is the bandgap reference voltage VBG and the source voltage is the voltage of the third node N3, as the bandgap reference voltage VBG gradually increases, the gate-source voltage difference of the fourth transistor M4 gradually increases, causing the source-drain current of the fourth transistor M4 to gradually decrease, thereby achieving a current limiting effect in response to changes in the bandgap reference voltage VBG.

[0085] The voltage of the second node N2 can control the conduction state of the fifth transistor M5. When the voltage of the second node N2 decreases as the voltage of the first node N1 decreases, the gate voltage of the fifth transistor M5 is equivalent to gradually decreasing. At this time, the fifth transistor M5 operates in the saturation region and can reduce the source-drain current in response to the gradually decreasing gate voltage, thereby achieving a current limiting effect.

[0086] The fourth transistor M4 and the fifth transistor M5 can both be P-type transistors, for example, P-channel MOSFETs. The gate of the fourth transistor M4 receives a bandgap reference voltage VBG. When the bandgap reference voltage VBG gradually increases, the source-drain current of the fourth transistor M4 gradually decreases. The gate of the fifth transistor M5 is connected to the second node N2 via an inverter. When the voltage of the second node N2 gradually decreases, the inverter can change the output low-level signal to a high-level signal when the voltage of the second node N2 drops below the transition threshold, causing the fifth transistor M5 to change from an on state to an off state, thereby achieving further current limiting. That is, at this time, the fifth transistor M5 switches between an off state and an on state.

[0087] In another example, the fifth transistor M5 may also be an N-type transistor, in which case the second node N2 may be directly connected to the gate of the fifth transistor M5. When the voltage of the second node N2 gradually decreases, the gate voltage of the fifth transistor M5 gradually decreases, and the source-drain current also gradually decreases.

[0088] It is understandable that the voltage of the second node N2 may also be set to increase as the voltage of the first node N1 decreases, and the type of the fifth transistor M5 and the corresponding added devices may be adaptively adjusted based on the above embodiment.

[0089] Referring to FIG. 4 , in some embodiments, the conversion module 40 may include a first inverter 41 , a second inverter 42 , and a second capacitor C2 .

[0090] The first inverter 41 may be connected between the first node N1 and the second inverter 42 , and the second inverter 42 may be connected between the first inverter 41 and the second node N2 .

[0091] The second capacitor C2 may be connected between the power terminal VCC and the second node N2.

[0092] When the startup circuit is powered on, the voltage of the power supply terminal VCC is pulled up to the power supply voltage. At this time, the second capacitor C2 can pull the second node N2 up to a high level signal through coupling boosting.

[0093] Taking the above embodiment, in which the fifth transistor M5 is a P-type transistor and is connected to the second node N2 via an inverter, as an example, the high-level signal at the second node N2 is converted to a low-level signal after passing through the inverter, driving the fifth transistor M5 to remain in the on state. In other words, the fifth transistor M5 does not perform a current limiting function at this time. Similarly, the bandgap reference voltage VBG has not yet increased, and can drive the fourth transistor M4 to remain in the on state. In other words, the fourth transistor M4 does not perform a current limiting function at this time. The coupled boost module 10 can quickly raise the potential of the first node N1.

[0094] As the voltage of the first node N1 gradually increases, the voltage of the first node N1 can be converted to the voltage of the second node N2 through the first inverter 41 and the second inverter 42. The two inversion conversion processes can filter out interference glitches in the voltage of the first node N1. When the voltage of the first node N1 is a high-level signal, the voltage of the second node N2 after the two inversions is also a high-level signal.

[0095] When the startup control module 20 increases the pull-down capability and the current limiting module 30 reduces the pull-up capability by current limiting, the potential of the first node N1 is pulled down, and the voltage of the second node N2, after two inversions, also becomes a low-level signal. This low-level signal is converted to a high-level signal after passing through the inverter, driving the fifth transistor M5 to turn off, further strengthening the current limiting function of the current limiting module 30.

[0096] Referring to FIG. 5 , in some embodiments, the startup circuit may further include an indication signal module 50 .

[0097] The indication signal module 50 may be connected to the second node N2 and generate an indication signal according to the voltage of the second node N2.

[0098] When the startup circuit is powered on, the second capacitor C2 can couple the voltage of the second node N2 to a high level signal, and as the voltage of the first node N1 increases, the voltage of the second node N2 will also maintain a high level signal.

[0099] After the startup circuit successfully starts the reference circuit 2, the bandgap reference voltage VBG output by the reference circuit 2 gradually increases, causing the voltage at the first node N1 to gradually decrease. Correspondingly, the voltage at the second node N2 switches from a high-level signal to a low-level signal. When the voltage at the second node N2 is a low-level signal, the fifth transistor M5 is driven to turn off. At this point, the startup circuit completes the startup of the reference circuit 2 and shuts down.

[0100] Since the voltage of the second node N2 becomes a low level signal only when the startup circuit is shut down, the indication signal module 50 can generate an indication signal when the voltage of the second node N2 is a low level signal to indicate that the startup circuit has completed startup and is shut down.

[0101] As an optional implementation, the indication signal module 50 may be an inverter. Since the voltage of the second node N2 becomes a low-level signal only after the startup circuit completes startup, the indication signal module 50 may invert the low-level signal and use it as an indication signal.

[0102] Referring to FIG6 , in some embodiments, the startup circuit may further include a voltage divider module 60. The voltage divider module 60 may be composed of at least one voltage divider unit, which may be disposed in at least one of the following locations:

[0103] Between the current limiting module 30 and the coupled boost module 10;

[0104] Between the start control module 20 and the ground terminal;

[0105] Coupling between the boost module 10 and the power supply terminal VCC;

[0106] between the conversion module 40 and the power supply terminal VCC; and

[0107] Between the conversion module 40 and the ground terminal.

[0108] The voltage divider unit is disposed between the current limiting module 30 and the coupled boost module 10 and is capable of stepping down the power supply voltage and providing it to the current limiting module 30. When the current limiting module 30 includes a fourth transistor M4, the voltage divider unit is capable of stepping down the power supply voltage and providing it to the source of the fourth transistor M4 to prevent the source voltage of the fourth transistor M4 from being too high. That is, by providing the voltage divider unit, when the reference circuit 2 outputs a stable bandgap reference voltage VBG, this bandgap reference voltage VBG, acting as the gate voltage of the fourth transistor M4, can minimize the source-drain current of the fourth transistor M4 or turn off the fourth transistor M4.

[0109] The voltage divider is disposed between the startup control module 20 and the ground terminal and is capable of raising the voltage at the bottom terminal of the startup control module 20. When the startup control module 20 includes a first transistor M1, the voltage divider can raise the source voltage of the first transistor M1, thereby reducing the gate-source voltage difference of the first transistor M1. When the reference circuit 2 outputs a stable bandgap reference voltage VBG, this bandgap reference voltage VBG, acting as the gate voltage of the first transistor M1, can minimize the source-drain current of the first transistor M1 or turn off the first transistor M1.

[0110] The voltage divider unit is arranged between the coupling boost module 10 and the power supply terminal VCC. When the coupling boost module 10 includes the second transistor M2, the voltage divider unit can be arranged between the source of the second transistor M2 and the power supply terminal VCC. The voltage divider unit can reduce the source voltage of the second transistor M2, so that the source-drain current of the second transistor M2 can be as small as possible under the current limiting effect of the current limiting module 30, or the second transistor M2 can be cut off.

[0111] The voltage divider unit can also be provided between the conversion module 40 and the power supply terminal VCC and between the conversion module 40 and the ground terminal. The first inverter 41 and the second inverter 42 in the conversion module 40 can be composed of two transistors of different types. For example, the first inverter 41 can include a P-type transistor and an N-type transistor. The P-type transistor is connected between the power supply terminal VCC and the second node N2, and the N-type transistor is connected between the ground terminal and the second node N2. The gate of the P-type transistor and the gate of the N-type transistor are connected to the first node N1. The voltage divider unit can also be provided between the conversion module 40 and the power supply terminal VCC, which is equivalent to the P-type transistor being connected to the power supply terminal VCC via the voltage divider unit; the voltage divider unit can also be provided between the conversion module 40 and the ground terminal, which is equivalent to the N-type transistor being connected to the ground terminal via the voltage divider unit. By providing an appropriate voltage divider unit, the source voltage of the P-type transistor and the source voltage of the N-type transistor can be adjusted so that the voltage variation range of the first node N1 can drive the P-type transistor and the N-type transistor to switch between the conductive states.

[0112] In some embodiments, the voltage dividing module 60 may include a voltage dividing MOSFET, wherein the gate and the drain of the voltage dividing MOSFET are connected.

[0113] Connecting the gate and drain of a MOSFET acts as a voltage-dropping diode. Placing a voltage-dividing MOSFET in the appropriate position can achieve a voltage-dropping effect, so that the source voltage of each transistor meets the requirements.

[0114] As an optional embodiment, the voltage-dividing MOSFET can be an N-channel MOSFET or a P-channel MOSFET. The voltage-dividing module 60 can include a single voltage-dividing MOSFET or can be composed of multiple voltage-dividing MOSFETs connected in series. As shown in FIG6 , the voltage-dividing module 60 disposed between the current-limiting module 30 and the coupled boost module 10 can be composed of a P-channel MOSFET and two N-channel MOSFETs connected in series.

[0115] In an optional embodiment, after software simulation verification based on the circuit topology schematic diagram shown in Figure 6, the static power consumption of the startup circuit at room temperature can reach less than 1nA, and the power consumption under the high temperature and high pressure FF (Fast N Fast P) process corner (worst case) does not exceed 10nA, with excellent power consumption performance.

[0116] The embodiment of the present application further provides a low-power reference source, which may include a reference circuit and a startup circuit provided in the embodiment of the present application. The reference circuit is connected to the startup circuit.

[0117] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of the present application are programs or code segments used to perform the required tasks. The programs or code segments can be stored in a machine-readable medium, or transmitted on a transmission medium or communication link via a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM (Read-Only Memory), flash memory, EROM (Erasable Read-Only Memory), floppy disks, CD-ROMs (Compact Disc Read-Only Memory), optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0118] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0119] This article uses specific examples to illustrate the principles and implementation methods of this application. The above examples are only used to help understand the method and core ideas of this application. The above are only optional implementation methods of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of this application, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of this application to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A startup circuit, the startup circuit being connected to a reference circuit; the startup circuit includes: A coupled boost module, connected to a first node, for coupling and boosting the voltage of the first node; wherein, the first node is used to provide an excitation voltage for a startup switch, and the startup switch is used to provide a startup current for the reference circuit when conducting; A startup control module, connected to the first node, for adjusting the voltage of the first node according to the bandgap reference voltage of the reference circuit; A current limiting module, connected to the coupled boost module, for adjusting the output current of the coupled boost module according to the bandgap reference voltage of the reference circuit; A conversion module, connected between the first node and a second node, for adjusting the voltage of the second node according to the voltage of the first node; wherein, the current limiting module is connected to the second node, and the current limiting module is further used to adjust the output current of the coupled boost module according to the voltage of the second node.

2. The startup circuit according to claim 1, wherein, The startup control module includes: A first transistor, connected between the first node and the ground terminal, and the gate of the first transistor is connected to the reference circuit; the bandgap reference voltage of the reference circuit is used to adjust the conduction state of the first transistor.

3. The startup circuit according to claim 1, wherein, The coupled boost module includes: A current source, connected between the first node and the power supply terminal, and the control terminal of the current source is connected to the current limiting module; A coupling unit, connected between the first node and the power supply terminal, for coupling and boosting the voltage of the first node when the power supply voltage is provided by the power supply terminal.

4. The startup circuit according to claim 3, wherein, The coupling unit includes a first capacitor, and the current source includes: A second transistor, connected between the first node and the power supply terminal; A third transistor, connected between the current limiting module and the power supply terminal, the gate of the third transistor is connected to the gate of the second transistor, and the gate of the third transistor is further connected to the current limiting module.

5. The startup circuit according to claim 1, wherein, The current limiting module includes: A fourth transistor, connected between the coupled boost module and a third node, and the gate of the fourth transistor is connected to the reference circuit; the bandgap reference voltage of the reference circuit is used to adjust the conduction state of the fourth transistor; A fifth transistor, connected between the third node and the ground terminal, and the gate of the fifth transistor is connected to the second node; the voltage of the second node is used to adjust the conduction state of the fifth transistor.

6. The startup circuit according to claim 1, wherein The conversion module includes: A first inverter and a second inverter, the first inverter is connected between the first node and the second inverter, and the second inverter is connected between the first inverter and the second node; A second capacitor, the second capacitor is connected between the power supply terminal and the second node.

7. The startup circuit according to claim 1, wherein The startup circuit further includes: An indication signal module, connected to the second node, for generating an indication signal according to the voltage of the second node.

8. The startup circuit according to claim 1, wherein, The startup circuit further includes a voltage dividing module, and the voltage dividing module is disposed in at least one of the following: Between the current limiting module and the coupled boost module; Between the startup control module and the ground terminal; Between the coupled boost module and the power supply terminal; between the conversion module and the power supply terminal; and, between the conversion module and the ground terminal.

9. The startup circuit according to claim 8, wherein The voltage dividing module includes a voltage dividing MOSFET, and the gate and the drain of the voltage dividing MOSFET are connected.

10. A low-power reference source, comprising a reference circuit and the startup circuit according to any one of claims 1-9.

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