Bandgap reference circuit based on feedback control and detection method of reference establishment signal

Abstract

The application discloses a band gap reference circuit based on feedback control and a detection method of reference establishment signal, the reference circuit comprises a first detection point formed by connecting a current mirror circuit and a band gap reference generation circuit, and the band gap reference generation circuit is provided with a second detection point; a detection circuit compares the voltages of the first detection point and the second detection point to judge the feedback loop state and output a band gap reference establishment state signal used for judging whether the band gap reference voltage is established. According to the application, the first detection point serves as a relative reference point, the second detection point rises with the rise of the power supply voltage before the band gap feedback loop is not established, and remains unchanged after the feedback loop is established due to the clamping of the band gap voltage in the feedback loop; the detection circuit compares the voltages of the first detection point and the second detection point to confirm whether the feedback loop is established, thereby determining whether the band gap reference voltage is established, so that the method can accurately and timely output the band gap reference establishment state signal in various scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuits, and in particular to a bandgap reference circuit based on feedback control and a detection method of reference establishment signal. BACKGROUND

[0002] Most chips integrate a bandgap reference (BGR) to generate a reference voltage or bias current, which is a ruler in the chip. The bandgap voltage of the bandgap reference is about 1.2V in normal operation, but this value is incorrect during the startup process, which will cause errors in the modules using the reference voltage or bias current in the system, and even lead to system failure or burning of the chip. Therefore, it is very important to timely and accurately determine whether the bandgap reference voltage has been correctly established during the startup process of the chip.

[0003] During the production process of the chip, due to process differences, the speed of power-on, working voltage and environmental temperature will be different in different application scenarios, so when designing the bandgap reference establishment signal (BG OK), these situations should be fully considered.

[0004] The prior art usually compares the voltage division of the bandgap voltage with the turn-on voltage of a MOS tube, and then adds a delay to generate a bandgap reference establishment signal. This method cannot accurately and timely generate the bandgap reference establishment signal under different power-on speeds, and the system still needs additional auxiliary detection circuits, and the delay of the signal during power-off is large.

[0005] Another solution is to compare the voltage division of the power supply with the voltage division of the bandgap voltage. This solution needs to increase additional voltage division resistors and power consumption, and its accuracy will be affected by the power supply, and it is difficult to meet the scene of wide power supply variation range, especially the low voltage scene.

[0006] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgment or any form of suggestion that this information forms prior art that is publicly known. SUMMARY

[0007] The purpose of the present application is to provide a bandgap reference circuit based on feedback control and a detection method of reference establishment signal, which can provide accurate and timely bandgap reference establishment signal during the startup process in various scenarios.

[0008] To achieve the above purpose, an embodiment of the present application provides a bandgap reference circuit based on feedback control, comprising a bandgap reference generation circuit and a current mirror circuit.

[0009] The bandgap reference generating circuit is used for generating a bandgap reference voltage; and the current mirror circuit is used for providing current to the bandgap reference generating circuit.

[0010] The bandgap reference circuit further comprises a start control circuit, a detection circuit, and the current mirror circuit and the bandgap reference generating circuit are connected, and a connection point forms a first detection point; a second detection point is formed in the bandgap reference generating circuit, and a voltage of the second detection point is clamped by a feedback loop of the bandgap reference generating circuit when the bandgap reference voltage is established; the start control circuit is used for controlling the voltage of the first detection point; and the detection circuit is connected with the first detection point and the second detection point, and is used for comparing the voltages of the first detection point and the second detection point to output a bandgap reference establishment signal used for judging whether the bandgap reference voltage is established.

[0011] In one or more embodiments of the present application, the start control circuit is used for pulling down the voltage of the first detection point to a low level in an initial stage of establishment of the bandgap reference voltage.

[0012] In one or more embodiments of the present application, the detection circuit outputs the bandgap reference establishment signal that the bandgap reference voltage is established when the voltage of the first detection point is greater than or equal to the voltage of the second detection point.

[0013] In one or more embodiments of the present application, the current mirror circuit comprises a first MOS transistor and a second MOS transistor connected in common gate, a third MOS transistor and a fourth MOS transistor connected in common gate, and a first resistor;

[0014] A drain of the first MOS transistor is connected with a source of the third MOS transistor, a drain of the second MOS transistor is connected with a source of the fourth MOS transistor, sources of the first MOS transistor and the second MOS transistor are connected with a power supply voltage, a first end of the first resistor is connected with a gate of the first MOS transistor and a drain of the third MOS transistor, a second end of the first resistor is connected with a gate of the third MOS transistor, the detection circuit, and the bandgap reference generating circuit, a connection point of the second end of the first resistor and the gate of the third MOS transistor constitutes the first detection point, and a drain of the fourth MOS transistor is connected with the bandgap reference generating circuit.

[0015] In one or more embodiments of the present application, the bandgap reference generating circuit comprises a fifth MOS transistor and a sixth MOS transistor connected in common gate, a seventh MOS transistor, a second resistor, a first triode, a second triode, a third resistor, a fourth resistor, and a fifth resistor;

[0016] The drain of the fifth MOS connects a current mirror circuit and a detection circuit, the gate and the drain of the sixth MOS are shorted and connect the gate of the seventh MOS and the current mirror circuit, the collector of the first triode connects the source of the fifth MOS, the base of the first triode connects the base of the second triode, the collector of the second triode connects the source of the sixth MOS and the detection circuit, the connection point of the collector of the second triode, the source of the sixth MOS and the detection circuit constitutes a second detection point, the emitter of the first triode connects the first end of the third resistor, the emitter of the second triode connects the second end of the third resistor and the first end of the fourth resistor, the second end of the fourth resistor is grounded, the drain of the seventh MOS connects the first end of the second resistor, the second end of the second resistor connects a power voltage, the source of the seventh MOS connects the base of the second triode, the first end of the fifth resistor and a bandgap reference voltage output end, and the second end of the fifth resistor is grounded.

[0017] In one or more embodiments of the present application, at the initial stage of establishing the bandgap reference voltage, the voltage of the first detection point is less than the voltage of the second detection point, and the voltage of the first detection point is:

[0018]

[0019] The voltage of the second detection point is:

[0020]

[0021] If the voltage of the first detection point is equal to the voltage of the second detection point, the bandgap reference voltage is established to a critical point, that is:

[0022]

[0023] Record , we can get:

[0024]

[0025] If the voltage of the first detection point is greater than the voltage of the second detection point, the feedback loop of the bandgap reference generation circuit has been established, and the voltage of the first detection point is:

[0026]

[0027] The voltage of the second detection point is:

[0028]

[0029] Wherein, is a power voltage, is a first current flowing through the first MOS and the third MOS, a second current flowing through the second MOS transistor and the fourth MOS transistor, a resistance value of the first resistor, a voltage between the gate and the source of the first MOS transistor, a resistance between the drain and the source of the second MOS transistor, a resistance between the drain and the source of the fourth MOS transistor, a voltage between the gate and the source of the sixth MOS transistor, a bandgap reference voltage, a voltage between the gate and the source of the seventh MOS transistor.

[0030] In one or more embodiments of the present application, the detection circuit includes a comparator, first and second inputs of the comparator are connected to the first and second detection points respectively, and the start control circuit controls the comparator based on the bandgap reference voltage.

[0031] The present application also discloses a method for detecting a bandgap reference establishing signal, the method comprising:

[0032] selecting a connection point of the bandgap reference generating circuit and the current mirror circuit as the first detection point;

[0033] selecting a connection point in the bandgap reference generating circuit as the second detection point, and the voltage of the selected second detection point is clamped by a feedback loop of the bandgap reference generating circuit when the bandgap reference voltage is established;

[0034] controlling the voltage of the first detection point at an initial stage of establishing the bandgap reference voltage;

[0035] comparing the voltages of the first and second detection points to determine a state of the feedback loop;

[0036] using the state of the feedback loop to represent whether the bandgap reference voltage is established.

[0037] In one or more embodiments of the present application, the controlling the voltage of the first detection point at the initial stage of establishing the bandgap reference voltage comprises:

[0038] pulling down the voltage of the first detection point to a low level, so that the voltage of the first detection point is lower than that of the second detection point.

[0039] In one or more embodiments of the present application, the comparing the voltages of the first and second detection points to determine whether the bandgap reference voltage is established comprises:

[0040] if the voltage of the first detection point is greater than or equal to that of the second detection point, the bandgap reference voltage is established;

[0041] If the voltage at the first detection point is less than the voltage at the second detection point, the bandgap reference voltage is not established.

[0042] Compared with the prior art, the present invention uses the connection point between the current mirror circuit and the bandgap reference generation circuit as the first detection point, and the connection point where the voltage is clamped by the feedback loop of the bandgap reference generation circuit when the bandgap reference voltage has been established as the second detection point. The detection circuit compares the voltages of the first detection point and the second detection point, and outputs a bandgap reference establishment signal to confirm whether the bandgap reference voltage has been established.

[0043] During power-up, the feedback loop in the bandgap reference generation circuit acts as a clamping mechanism. Once the bandgap reference voltage is established, the second detection point is clamped to a fixed voltage value by the bandgap reference voltage. Simultaneously, the voltage at the first detection point continues to increase with the increase of the power supply voltage AVDD, allowing the voltage at the first detection point to increase rapidly even at low power-up speeds. Therefore, this circuit can accurately and promptly output the bandgap reference establishment signal at different power-up speeds. Furthermore, in the event of a power failure leading to a power outage, this invention can quickly activate the startup control circuit, which disables the detection circuit, thus ceasing the output of the bandgap reference establishment signal.

[0044] This invention can correctly generate a bandgap reference establishment signal with established bandgap reference voltage within the system power-on speed range of 0.27uV / us to 5.5V / us, and the transmission delay is short. It does not require additional auxiliary circuits, and the implementation method is simple, saves power consumption and cost.

[0045] This invention has a clear logic, is easy to implement, can speed up the system power-on speed, and can also send signals in a timely manner to protect the system in the event of abnormal power failure or system malfunction. Attached Figure Description

[0046] Figure 1 This is a circuit schematic diagram of a bandgap reference circuit based on feedback control according to an embodiment of the present invention.

[0047] Figure 2 This is a graph showing the relationship between the total drain-source resistance and the total drain-source voltage of the second and fourth MOS transistors according to an embodiment of the present invention during the startup process.

[0048] Figure 3 This is a graph showing the relationship between the first current and the second current and the total drain-source voltage of the second and fourth MOSFETs during the startup process, according to an embodiment of the present invention.

[0049] Figure 4 This is a flowchart of a method for detecting a bandgap reference establishment signal according to an embodiment of the present invention. Detailed Implementation

[0050] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0051] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0052] like Figure 1 As shown, a bandgap reference circuit for signal detection based on a bandgap reference includes: a current mirror circuit 10, a bandgap reference generation circuit 20, a start-up control circuit, and a detection circuit.

[0053] A bandgap reference generation circuit 20 is used to generate a bandgap reference voltage. A current mirror circuit 10 is used to provide current to the bandgap reference generation circuit 20. The current mirror circuit 10 is connected to the bandgap reference generation circuit 20, and the connection point forms a first detection point BGOK_P. A second detection point BGOK_N is formed in the bandgap reference generation circuit 20. A start-up control circuit is connected to the first detection point BGOK_P and is used to control the voltage at the first detection point BGOK_P. A detection circuit is connected to the first detection point BGOK_P and the second detection point BGOK_N. The detection circuit compares the voltages at the first detection point BGOK_P and the second detection point BGOK_N to output a bandgap reference establishment signal BG_OK, used to determine whether the bandgap reference voltage VBG has been established.

[0054] In this embodiment, the second detection point BGOK_N can be selected based on the condition that the voltage will be clamped by the feedback loop of the bandgap reference generation circuit 20 when the bandgap reference voltage VBG has been established.

[0055] like Figure 1 As shown, the current mirror circuit 10 includes a first MOSFET M1 and a second MOSFET M2 connected by a common gate, a third MOSFET M3 and a fourth MOSFET M4 connected by a common gate, and a first resistor R1.

[0056] Specifically, the drain of the first MOSFET M1 is connected to the source of the third MOSFET M3, and the drain of the second MOSFET M2 is connected to the source of the fourth MOSFET M4. The sources of the first MOSFET M1 and the second MOSFET M2 are connected to the power supply voltage AVDD. The first terminal of the first resistor R1 is connected to the gate of the first MOSFET M1 and the drain of the third MOSFET M3, and the second terminal of the first resistor R1 is connected to the gate of the third MOSFET M3, the detection circuit, and the bandgap reference generation circuit 20. The connection point between the second terminal of the first resistor R1, the gate of the third MOSFET M3, and the detection circuit constitutes the first detection point BGOK_P. The drain of the fourth MOSFET M4 is connected to the bandgap reference generation circuit 20.

[0057] like Figure 1 As shown, the bandgap reference generation circuit 20 includes a common-gate connected fifth MOSFET M5 and sixth MOSFET M6, seventh MOSFET M7, second resistor R2, first transistor Q1, second transistor Q2, third resistor R3, fourth resistor R4, and fifth resistor R5.

[0058] Specifically, the drain of the fifth MOSFET M5 is connected to the current mirror circuit 10 and the detection circuit. The gate and drain of the sixth MOSFET M6 are shorted and connected to the gate of the seventh MOSFET M7 and the current mirror circuit 10. The collector of the first transistor Q1 is connected to the source of the fifth MOSFET M5. The base of the first transistor Q1 is connected to the base of the second transistor Q2. The collector of the second transistor Q2 is connected to the source of the sixth MOSFET M6 and the detection circuit. The connection point between the collector of the second transistor Q2, the source of the sixth MOSFET, and the detection circuit constitutes the second detection point BGOK_N. The emitter of the first transistor Q1 is connected to the first terminal of the third resistor R3. The emitter of the second transistor Q2 is connected to the second terminal of the third resistor R3 and the first terminal of the fourth resistor R4. The second terminal of the fourth resistor R4 is grounded. The drain of the seventh MOSFET M7 is connected to the first terminal of the second resistor R2, the second terminal of the second resistor R2 is connected to the power supply voltage AVDD, the source of the seventh MOSFET M7 is connected to the base of the second transistor Q2, the first terminal of the fifth resistor R5 and the bandgap reference output terminal, and the second terminal of the fifth resistor R5 is grounded.

[0059] The second resistor R2, the sixth MOSFET M6, the seventh MOSFET M7, the second transistor Q2, and the fifth resistor R5 constitute a feedback loop for clamping the voltage at the second detection point BGOK_N. Whether the feedback loop and the current mirror circuit 10 are established is a crucial factor in determining whether the bandgap reference voltage VBG is established.

[0060] As described above, the connection point between the second terminal of the first resistor R1, the gate of the third MOSFET M3, and the drain of the fifth MOSFET is the first detection point BGOK_P. The connection point between the source of the sixth MOSFET M6 and the collector of the second transistor Q2 is the second detection point BGOK_N. By using the connection point between the source of the sixth MOSFET M6 and the collector of the second transistor Q2 as the second detection point BGOK_N, the power supply voltage AVDD range is above 2.7V, providing a wider range while maintaining measurement accuracy. In other embodiments, the gate of the sixth MOSFET M6 can be selected as the second detection point BGOK_N, providing a power supply voltage AVDD range above 4V while maintaining measurement accuracy.

[0061] like Figure 1 As shown, the detection circuit includes a comparator COMP, whose first and second input terminals are respectively connected to the first detection point BGOK_P and the second detection point BGOK_N. In this embodiment, the first input terminal of the comparator COMP is a positive input terminal and is connected to the first detection point BGOK_P, and the second input terminal of the comparator COMP is a negative input terminal and is connected to the second detection point BGOK_N. In other embodiments, the positive and negative input terminals of the comparator COMP can be interchanged.

[0062] like Figure 1 As shown, the first control terminal of the start control circuit is connected to the first detection point BGOK_P, and the second control terminal of the start control circuit is connected to the enable terminal of the comparator COMP. By controlling the enable terminal of the comparator COMP, the comparator COMP is prevented from outputting an incorrect result when the current in the two branches connected to the first and second input terminals of the comparator COMP is 0.

[0063] During the initial establishment of the bandgap reference voltage VBG, the start-up control circuit pulls down the voltage of the first detection point BGOK_P to a low potential through the first control terminal, making the voltage of the first detection point BGOK_P less than that of the second detection point. The voltage at the first detection point BGOK_P and the voltage at the second detection point when the bandgap reference voltage VBG is not established. The voltages of both transistors increase with the power supply voltage AVDD. At this time, the first current flowing through the first MOSFET M1 and the third MOSFET M3... The second current is greater than the current flowing through the second MOSFET M2 and the fourth MOSFET M4.

[0064] The corresponding first detection point The voltage is:

[0065]

[0066] Second testing point The voltage is:

[0067]

[0068] In the initial stage of establishing the bandgap reference voltage VBG, the second MOSFET M2 and the fourth MOSFET M4 are considered as switching transistors. First testing point The voltage is less than the second detection point At this voltage, the bandgap reference establishment signal BG_OK output from the comparator COMP is "0".

[0069] With the establishment of the bandgap reference voltage VBG, if the voltage at the first detection point BGOK_P is greater than or equal to the voltage at the second detection point BGOK_N, then the surface bandgap reference voltage VBG has been established. In this embodiment, although the surface bandgap reference voltage VBG is established when the voltage at the first detection point BGOK_P is greater than or equal to the voltage at the second detection point BGOK_N, the bandgap reference voltage VBG is not fully established when the voltage at the first detection point BGOK_P is equal to the voltage at the second detection point BGOK_N, considering the safe operation of the comparator COMP and anti-interference reasons. This is because the bandgap reference voltage VBG has reached the critical point of establishment. Only when the voltage at the first detection point BGOK_P is greater than the voltage at the second detection point BGOK_N does it indicate that the bandgap reference voltage VBG has been fully established.

[0070] If the voltage at the first detection point BGOK_P is equal to the voltage at the second detection point BGOK_N, the surface bandgap reference voltage VBG is established to the critical point, that is:

[0071]

[0072] remember We can obtain:

[0073]

[0074] The value changes very little and can be considered constant. By setting the sixth MOSFET M6 and the first MOSFET M1 to different width-to-length ratios and combining this with the fact that the first current I1 is greater than the second current I2, therefore... .

[0075] If the voltage at the first detection point BGOK_P is greater than the voltage at the second detection point BGOK_N, the feedback loop of the bandgap reference generation circuit has been established. Therefore, the voltage at the first detection point BGOK_P is:

[0076]

[0077] The voltage at the second detection point BGOK_N is:

[0078]

[0079] It can be seen that, compared to when the bandgap reference voltage VBG is established to the critical point, the expression for the voltage at the first detection point BGOK_P remains unchanged when the bandgap reference voltage VBG is established, while the voltage at the second detection point BGOK_N is eventually clamped to approximately 1.2V. When the voltage at the first detection point BGOK_P is greater than the voltage at the second detection point BGOK_N, the bandgap reference establishment signal BG_OK output from the comparator COMP is "1".

[0080] Without considering the safe operation and interference immunity of the comparator COMP, the first current I1 when the bandgap reference voltage VBG is established is equal to the second current I2. It can be simplified to , It is a constant.

[0081] In the above expressions, This is the power supply voltage. The first current flowing through the first MOSFET M1 and the third MOSFET M3, The second current flowing through the second MOSFET M2 and the fourth MOSFET M4, Let R1 be the resistance value of the first resistor. This is the voltage between the gate and source of the first MOSFET M1. The resistance between the drain and source of the second MOSFET M2 is... The resistance between the drain and source of the fourth MOSFET M4 is... This is the voltage between the gate and source of the sixth MOSFET M6. The bandgap reference voltage, This is the voltage between the gate and source of the seventh MOSFET M7.

[0082] like Figure 2 As shown, during the establishment of the bandgap reference voltage VBG, the resistance between the drain and source of the second MOS transistor M2... The resistance between the drain and source of the fourth MOSFET M4 The sum will vary with the voltage between the drain and source of the second MOSFET M2. The voltage between the drain and source of the fourth MOSFET M4 The sum of them changes.

[0083] In voltage With voltage When the sum is less than 200uV, the second MOSFET M2 and the fourth MOSFET M4 are in the cutoff state, and the resistor... With resistance The sum is very large. With voltage... With voltage As the sum increases, the second MOSFET M2 and the fourth MOSFET M4 enter the linear region. This is due to the voltage between the gate and source of the second MOSFET M2. The voltage between the gate and source of the fourth MOSFET M4 Both are only around 1V, therefore the sum of the linear resistances of the second MOSFET M2 and the fourth MOSFET M4 is between 10kΩ and 20kΩ, and the voltage... and voltage When the sum of the voltages exceeds 0.2V, the second MOSFET M2 and the fourth MOSFET M4 enter the saturation region, and the resistance... With resistance The sum of them rose sharply.

[0084] like Figure 3 As shown, during the establishment of the bandgap reference voltage VBG, the first current I1 flowing through the first MOSFET M1 and the third MOSFET M3, and the second current I2 flowing through the second MOSFET M2 and the fourth MOSFET M4, will change with the voltage between the drain and source of the second MOSFET M2. The voltage between the drain and source of the fourth MOSFET M4 The sum of them changes.

[0085] In the initial stage of establishing the bandgap reference voltage VBG, the voltage of the first detection point BGOK_P is lowered by the start-up control circuit, causing the first current I1 to increase rapidly. After the start-up control circuit is turned off, the first current I1 and the second current I2 gradually approach each other and eventually become equal through the adjustment of the current mirror circuit and the feedback loop.

[0086] like Figure 4 As shown, this embodiment also discloses a method for detecting a bandgap reference establishment signal. The detection method is based on the above-mentioned bandgap reference circuit and includes:

[0087] S1. Select the connection point between the bandgap reference generation circuit 20 and the current mirror circuit 10 as the first detection point BGOK_P.

[0088] S2. Select a connection point in the bandgap reference generation circuit 20 as the second detection point BGOK_N. The voltage of the selected second detection point BGOK_N is clamped by the feedback loop of the bandgap reference generation circuit when the bandgap reference voltage VBG has been established.

[0089] S3. In the initial stage of establishing the bandgap reference voltage VBG, control the voltage of the first detection point BGOK_P; specifically, pull down the voltage of the first detection point BGOK_P to a low potential, so that the voltage of the first detection point BGOK_P is less than the voltage of the second detection point BGOK_N.

[0090] S4. Compare the voltages at the first detection point BGOK_P and the second detection point BGOK_N to determine the state of the feedback loop.

[0091] S5. The state of the bandgap reference circuit is characterized by the feedback loop state. Specifically, it is determined whether the bandgap reference voltage VBG is established. If the voltage at the first detection point BGOK_P is greater than or equal to the voltage at the second detection point BGOK_N, the bandgap reference voltage VBG has been established. If the voltage at the first detection point BGOK_P is less than the voltage at the second detection point BGOK_N, the bandgap reference voltage VBG has not been established. In this embodiment, if the voltage at the first detection point BGOK_P is equal to the voltage at the second detection point BGOK_N, it indicates that the bandgap reference voltage VBG has been established to the critical point. If the voltage at the first detection point BGOK_P is greater than the voltage at the second detection point BGOK_N, it indicates that the bandgap reference voltage VBG has been fully established.

[0092] As can be seen from the above technical solution, the present invention has the following beneficial effects:

[0093] This invention uses the connection point between the current mirror circuit and the bandgap reference generation circuit as the first detection point, and the connection point where the voltage is clamped by the feedback loop of the bandgap reference generation circuit when the bandgap reference voltage has been established as the second detection point. The first detection point serves as a relative reference point. The second detection point rises with the power supply voltage before the bandgap feedback loop is established, and remains unchanged after the feedback loop is established due to the clamping effect of the bandgap reference voltage in the feedback loop. The detection circuit compares the voltages at the first and second detection points to confirm whether the feedback loop has been established, and outputs a bandgap reference establishment signal to confirm whether the bandgap reference voltage has been established. This allows for accurate and timely signal output in various scenarios.

[0094] This invention can correctly generate a bandgap reference establishment signal with established bandgap reference voltage within the system power-on speed range of 0.27uV / us to 5.5V / us, and the transmission delay is short. It does not require additional auxiliary circuits, and the implementation method is simple, saves power consumption and cost.

[0095] This invention is applicable over a fairly wide range of power supply voltages, with the lowest applicable power supply voltage being slightly higher than the bandgap voltage plus the threshold voltages of two MOS transistors.

[0096] This invention has a clear logic, is easy to implement, can speed up the system power-on speed, and can also send signals in a timely manner to protect the system in the event of abnormal power failure or system malfunction.

[0097] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A bandgap reference circuit based on feedback control, comprising: A bandgap reference generation circuit is used to generate a bandgap reference voltage. A current mirror circuit is used to supply current to the bandgap reference generation circuit. The bandgap reference circuit is characterized in that it further includes: The current mirror circuit is connected to the bandgap reference generation circuit, and the connection point forms the first detection point; A second detection point is formed in the bandgap reference generation circuit. The voltage of the second detection point is clamped by the feedback loop of the bandgap reference generation circuit when the bandgap reference voltage has been established. A start-up control circuit is used to control the voltage at the first detection point; and A detection circuit, connected to a first detection point and a second detection point, is used to compare the voltages at the first detection point and the second detection point to output a bandgap reference establishment signal for determining whether a bandgap reference voltage has been established. The current mirror circuit includes a first MOSFET and a second MOSFET connected in common gate, a third MOSFET and a fourth MOSFET connected in common gate, and a first resistor; The drain of the first MOSFET is connected to the source of the third MOSFET, the drain of the second MOSFET is connected to the source of the fourth MOSFET, the sources of the first MOSFET and the second MOSFET are connected to the power supply voltage, the first end of the first resistor is connected to the gate of the first MOSFET and the drain of the third MOSFET, the second end of the first resistor is connected to the gate of the third MOSFET, the detection circuit and the bandgap reference generation circuit, the connection point of the second end of the first resistor, the gate of the third MOSFET and the detection circuit constitutes the first detection point, and the drain of the fourth MOSFET is connected to the bandgap reference generation circuit. The bandgap reference generation circuit includes a common-gate connected fifth and sixth MOS transistors, a seventh MOS transistor, a second resistor, a first transistor, a second transistor, a third resistor, and a fifth resistor; The drain of the fifth MOSFET is connected to the current mirror circuit and the detection circuit. The gate and drain of the sixth MOSFET are shorted and connected to the gate of the seventh MOSFET and the current mirror circuit. The collector of the first transistor is connected to the source of the fifth MOSFET. The base of the first transistor is connected to the base of the second transistor. The collector of the second transistor is connected to the source of the sixth MOSFET and the detection circuit. The connection point of the collector of the second transistor, the source of the sixth MOSFET, and the detection circuit constitutes the second detection point. The emitter of the first transistor is connected to the first end of the third resistor. The second end of the third resistor is grounded. The emitter of the second transistor is grounded. The drain of the seventh MOSFET is connected to the first end of the second resistor. The second end of the second resistor is connected to the power supply voltage. The source of the seventh MOSFET is connected to the base of the second transistor, the first end of the fifth resistor, and the bandgap reference voltage output terminal. The second end of the fifth resistor is grounded.

2. The bandgap reference circuit based on feedback control as described in claim 1, characterized in that, The startup control circuit is used to pull down the voltage of the first detection point to a low potential during the initial stage of establishing the bandgap reference voltage.

3. The bandgap reference circuit based on feedback control as described in claim 1, characterized in that, When the voltage at the first detection point is greater than or equal to the voltage at the second detection point, the detection circuit outputs a bandgap reference establishment signal indicating that the bandgap reference voltage has been established.

4. The bandgap reference circuit based on feedback control as described in claim 1, characterized in that, The bandgap reference generation circuit includes a fourth resistor; the emitter of the second transistor is connected to the second end of the third resistor and the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

5. The bandgap reference circuit based on feedback control as described in claim 1, characterized in that, In the initial stage of establishing the bandgap reference voltage, the voltage at the first detection point is less than the voltage at the second detection point. The voltage at the first detection point is: The voltage at the second detection point is: If the voltage at the first detection point is equal to the voltage at the second detection point, the bandgap reference voltage is established to the critical point, that is: remember We can obtain: If the voltage at the first detection point is greater than the voltage at the second detection point, the feedback loop of the bandgap reference generation circuit has been established, and the voltage at the first detection point is: The voltage at the second detection point is: in, This is the power supply voltage. The first current flowing through the first MOSFET and the third MOSFET, The second current flowing through the second and fourth MOSFETs, This is the resistance value of the first resistor. This is the voltage between the gate and source of the first MOSFET. The resistance between the drain and source of the second MOSFET is... The resistance between the drain and source of the fourth MOSFET is... This is the voltage between the gate and source of the sixth MOSFET. The bandgap reference voltage, This is the voltage between the gate and source of the seventh MOSFET.

6. The bandgap reference circuit based on feedback control as described in claim 1, characterized in that, The detection circuit includes a comparator, the first input terminal and the second input terminal of the comparator are respectively connected to the first detection point and the second detection point, and the start control circuit enables the comparator according to the bandgap reference voltage.

7. A method for detecting a bandgap reference establishment signal, characterized in that, Based on the feedback-controlled bandgap reference circuit as described in any one of claims 1 to 6, the detection method includes: The connection point between the bandgap reference generation circuit and the current mirror circuit is selected as the first detection point. A connection point in the bandgap reference generation circuit is selected as the second detection point. The voltage at the selected second detection point is clamped by the feedback loop of the bandgap reference generation circuit when the bandgap reference voltage has been established. In the initial stage of establishing the bandgap reference voltage, control the voltage at the first detection point; Compare the voltages at the first and second detection points to determine the state of the feedback loop; The state of the feedback loop is used to characterize whether the bandgap reference voltage has been established.

8. The method for detecting the bandgap reference establishment signal as described in claim 7, characterized in that, In the initial stage of establishing the bandgap reference voltage, controlling the voltage at the first detection point includes: Pull the voltage of the first detection point down to a low potential, so that the voltage of the first detection point is less than the voltage of the second detection point.

9. The method for detecting the bandgap reference establishment signal as described in claim 7, characterized in that, Comparing the voltages at the first and second detection points to determine whether a bandgap reference voltage has been established includes: If the voltage at the first detection point is greater than or equal to the voltage at the second detection point, the bandgap reference voltage has been established; If the voltage at the first detection point is less than the voltage at the second detection point, the bandgap reference voltage is not established.

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