CN115993864A - Band gap reference circuit based on feedback control and detection method of reference establishment signal - Google Patents

Abstract

The invention discloses a band-gap reference circuit based on feedback control and a detection method of a reference establishment signal, wherein the reference circuit comprises a first detection point formed by connecting a current mirror circuit and a band-gap reference generating circuit, and a second detection point is arranged in the band-gap reference generating circuit; the detection circuit compares the voltages of the first detection point and the second detection point to judge the feedback loop state so as to output a band gap reference establishment state signal for judging whether the band gap reference voltage is established or not. According to the method, the first detection point is used as a relative reference point, the second detection point rises along with the rising of the power supply voltage before the band gap feedback loop is not established, the second detection point is kept unchanged by clamping of the band gap voltage in the feedback loop after the establishment of the feedback loop is completed, and the detection circuit compares the voltages of the first detection point and the second detection point to determine whether the feedback loop is established or not, so that whether the band gap reference voltage is established or not is determined, and therefore, the method can accurately and timely output band gap reference establishment state signals in various scenes.

Description

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

Technical Field

The present invention relates to the field of integrated circuits, and more particularly, to a band gap reference circuit based on feedback control and a method for detecting a reference setup signal.

Background

A bandgap reference (Bandgap reference, BGR) is integrated in most chips that generates a reference voltage or bias current, the bandgap reference being a scale in the chip. The bandgap voltage of the bandgap reference is about 1.2V in normal operation, but during start-up, the value is incorrect, which can cause errors in the modules in the system that use the reference voltage or bias current, and even cause the system to fail to start-up or burn-in. Therefore, in the chip start-up process, it is important to timely and accurately determine whether the bandgap reference voltage has been properly established.

In the production process of the chip, the power-on speed, the working voltage and the ambient temperature are different under different application scenes due to the process difference, so that the situations are fully considered when the band gap reference building signal (BG_OK) is designed.

In the prior art, the voltage division of the band gap voltage is compared with one starting voltage of the MOS tube, and then one-stage delay is added to generate a band gap reference established signal.

Another solution is to compare the divided voltage of the power supply with the divided voltage of the bandgap voltage, which requires additional voltage dividing resistance and power consumption, and the accuracy of which is affected by the power supply, and it is difficult to simultaneously satisfy a wide range of power supply variation, especially a low voltage scenario.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a band-gap reference circuit based on feedback control and a detection method of a reference established signal, which can provide accurate and timely band-gap reference established signals in the starting process under various scenes.

To achieve the above object, an embodiment of the present invention provides a bandgap reference circuit based on feedback control, including: a bandgap reference generation circuit and a current mirror circuit.

The band gap reference generating circuit is used for generating a band gap reference voltage; the current mirror circuit is used for providing current to the band gap reference generating circuit.

The bandgap reference circuit further includes: the starting control circuit, the detection circuit and the current mirror circuit are connected with the band gap reference generating circuit, and the connection point forms a first detection point; a second detection point is formed in the band-gap reference generating circuit, and the voltage of the second detection point is clamped by a feedback loop of the band-gap reference generating circuit when the band-gap reference voltage is established; the starting control circuit is used for controlling the voltage of the first detection point; 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 band gap reference establishment signal for judging whether band gap reference voltage is established or not.

In one or more embodiments of the present invention, the start-up control circuit is configured to pull down the voltage at the first detection point to a low level at an initial stage of the bandgap reference voltage establishment.

In one or more embodiments of the present invention, the detection circuit outputs a bandgap reference setup signal in which the bandgap reference voltage is established when the voltage at the first detection point is greater than or equal to the voltage at the second detection point.

In one or more embodiments of the present invention, the current mirror circuit includes 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;

the drain electrode of the first MOS tube is connected with the source electrode of the third MOS tube, the drain electrode of the second MOS tube is connected with the source electrode of the fourth MOS tube, the source electrodes of the first MOS tube and the second MOS tube are connected with the power supply voltage, the first end of the first resistor is connected with the grid electrode of the first MOS tube and the drain electrode of the third MOS tube, the second end of the first resistor is connected with the grid electrode of the third MOS tube, the detection circuit and the band gap reference generation circuit, the connection points of the second end of the first resistor, the grid electrode of the third MOS tube and the detection circuit form a first detection point, and the drain electrode of the fourth MOS tube is connected with the band gap reference generation circuit.

In one or more embodiments of the present invention, the bandgap reference generating circuit includes fifth and sixth MOS transistors, a seventh MOS transistor, a second resistor, a first transistor, a second transistor, a third resistor, a fourth resistor, and a fifth resistor connected by a common gate;

the drain electrode of the fifth MOS tube is connected with the current mirror circuit and the detection circuit, the grid electrode and the drain electrode of the sixth MOS tube are in short circuit and are connected with the grid electrode and the current mirror circuit of the seventh MOS tube, the collector electrode of the first MOS tube is connected with the source electrode of the fifth MOS tube, the base electrode of the first MOS tube is connected with the base electrode of the second MOS tube, the collector electrode of the second MOS tube is connected with the source electrode of the sixth MOS tube and the detection circuit, the connection points of the collector electrode of the second MOS tube, the source electrode of the sixth MOS tube and the detection circuit form a second detection point, the emitter electrode of the first MOS tube is connected with the first end of the third resistor, the emitter electrode of the second MOS tube is connected with 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 electrode of the seventh MOS tube is connected with the first end of the second resistor, the second end of the second resistor is connected with the power supply voltage, the source electrode of the seventh MOS tube is connected with the first end of the second MOS tube, the fifth resistor and the band gap voltage output end, and the fifth resistor is grounded.

In one or more embodiments of the present invention, in an early stage of the bandgap reference voltage establishment, a voltage at a first detection point is less than a voltage at a second detection point, and the voltage at the first detection point is:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage of the second detection point is as follows:

VBGOK_N＝AVDD-I2×(Rds2+Rds4)-Vgs6

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 a critical point, namely:

AVDD-I1×R1-|Vgs1|＝AVDD-I2×(Rds2+Rds4)-Vgs6

note Δvgs=vgs 6- |vgs1| can be obtained:

R1＝I2/I1×(Rds2+Rds4)+ΔVgs/I1

if the voltage of the first detection point is greater than the voltage of the second detection point, the feedback loop of the band gap reference generating circuit is established, and the voltage of the first detection point is:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage of the second detection point is as follows:

VBGOK_N＝VBG+Vgs7-Vgs6

wherein AVDD is a power supply voltage, I1 is a first current flowing through the first MOS transistor and the third MOS transistor, I2 is a second current flowing through the second MOS transistor and the fourth MOS transistor, R1 is a resistance value of the first resistor, vgs1 is a voltage between the gate and the source of the first MOS transistor, rds2 is a resistance between the drain and the source of the second MOS transistor, rds4 is a resistance between the drain and the source of the fourth MOS transistor, vgs6 is a voltage between the gate and the source of the sixth MOS transistor, VBG is a bandgap reference voltage, and Vgs7 is a voltage between the gate and the source of the seventh MOS transistor.

In one or more embodiments of the present invention, the detection circuit includes a comparator, a first input terminal and a second input terminal of the comparator are respectively connected to a first detection point and a second detection point, and the start control circuit performs enable control on the comparator according to a bandgap reference voltage.

The invention also discloses a detection method of the band gap reference establishment signal, which comprises the following steps:

selecting a connection point of the band gap reference generating circuit and the current mirror circuit as a first detection point;

selecting a connection point in the band-gap reference generating circuit as a second detection point, wherein the voltage of the selected second detection point is clamped by a feedback loop of the band-gap reference generating circuit when the band-gap reference voltage is established;

controlling the voltage of the first detection point at the initial stage of the establishment of the band gap reference voltage;

comparing the voltages of the first detection point and the second detection point to judge the feedback loop state;

the feedback loop state is used to characterize whether the bandgap reference voltage is established.

In one or more embodiments of the present invention, controlling the voltage at the first detection point at an initial stage of the bandgap reference voltage establishment includes:

and pulling down the voltage of the first detection point to a low potential so that the voltage of the first detection point is smaller than the voltage of the second detection point.

In one or more embodiments of the present invention, comparing the voltages at the first detection point and the second detection point to determine whether the bandgap reference voltage is established includes:

if the voltage of the first detection point is greater than or equal to the voltage of the second detection point, the band gap reference voltage is established;

if the voltage of the first detection point is smaller than the voltage of the second detection point, the band gap reference voltage is not established.

Compared with the prior art, the invention uses the connection point of the current mirror circuit and the band gap reference generating circuit as a first detection point, uses the connection point of the voltage clamped by the feedback loop of the band gap reference generating circuit when the band gap reference voltage is established as a second detection point, compares the voltages of the first detection point and the second detection point through the detection circuit, and outputs a band gap reference establishing signal to confirm whether the band gap reference voltage is established.

In the power-on process, the feedback loop in the band-gap reference generating circuit is used as a clamping function, when the establishment of the band-gap reference voltage is completed, the second detection point is clamped to a fixed voltage value by the band-gap reference voltage, and meanwhile, the voltage of the first detection point is continuously increased along with the increase of the power supply voltage AVDD, so that the voltage of the first detection point can be rapidly increased under the condition of lower power-on speed of the AVDD. Therefore, the circuit can accurately and timely output band gap reference establishment signals at different power-on speeds. In addition, under the condition of power failure caused by power failure abnormality, the invention can quickly act on the starting control circuit, and the starting control circuit controls the detection circuit to be in a non-enabling state, and the band gap reference establishment signal is not output any more.

The invention can correctly send out the band-gap reference establishment signal with established band-gap reference voltage within the range of 0.27uV/us to 5.5V/us in the system power-on speed, has short sending delay, does not need an additional auxiliary circuit, has simple implementation mode and saves power consumption and cost.

The invention has clear logic and convenient realization, can accelerate the power-on speed of the system, and can also timely and rapidly send out signals to protect the system when the power supply is abnormally powered off or the system is abnormally.

Drawings

Fig. 1 is a circuit schematic of a feedback control based bandgap reference circuit in accordance with an embodiment of the invention.

Fig. 2 is a graph of drain-source total resistance versus drain-source total voltage of the second MOS transistor and the fourth MOS transistor during start-up according to an embodiment of the present invention.

Fig. 3 is a graph of the first and second currents versus the total drain-source voltages of the second and fourth MOS transistors during start-up according to an embodiment of the present invention.

Fig. 4 is a flowchart of a method for detecting a bandgap reference setup signal according to an embodiment of the invention.

Detailed Description

Specific embodiments of the invention will be described in detail below with reference to the drawings, but it should be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.

As shown in fig. 1, a bandgap reference circuit for detecting a bandgap reference based on a bandgap reference setup signal, includes: a current mirror circuit 10, a bandgap reference generation circuit 20, a start control circuit and a detection circuit.

The bandgap reference generation circuit 20 is used for generating a bandgap reference voltage. The current mirror circuit 10 is used to supply current to the bandgap reference generating circuit 20. The current mirror circuit 10 is connected to the bandgap reference generating circuit 20, and the connection point forms a first detection point bgok_p, and a second detection point bgok_n is formed in the bandgap reference generating circuit 20. The start control circuit is connected with the first detection point BGOK_P and is used for controlling the voltage of the first detection point BGOK_P. The detection circuit is connected with the first detection point BGOK_P and the second detection point BGOK_N, and is used for comparing the voltages of the first detection point BGOK_P and the second detection point BGOK_N to output a band gap reference establishment signal BG_OK for judging whether the band gap reference voltage VBG is established or not.

In the present embodiment, the second detection point bgok_n may be selected on the condition that the voltage is clamped by the feedback loop of the bandgap reference generating circuit 20 in the case where the bandgap reference voltage VBG is established.

As shown in fig. 1, the current mirror circuit 10 includes a first MOS transistor M1 and a second MOS transistor M2 connected in common gate, a third MOS transistor M3 and a fourth MOS transistor M4 connected in common gate, and a first resistor R1.

Specifically, the drain electrode of the first MOS transistor M1 is connected to the source electrode of the third MOS transistor M3, the drain electrode of the second MOS transistor M2 is connected to the source electrode of the fourth MOS transistor M4, and the source electrodes of the first MOS transistor M1 and the second MOS transistor M2 are connected to the power supply voltage AVDD. The first end of the first resistor R1 is connected to the gate of the first MOS transistor M1 and the drain of the third MOS transistor M3, and the second end of the first resistor R1 is connected to the gate of the third MOS transistor M3, the detection circuit, and the bandgap reference generation circuit 20. The second end of the first resistor R1, and the connection point between the gate of the third MOS transistor M3 and the detection circuit form a first detection point bgok_p. The drain electrode of the fourth MOS transistor M4 is connected with the band gap reference generating circuit 20.

As shown in fig. 1, the bandgap reference generating circuit 20 includes a fifth MOS transistor M5 and a sixth MOS transistor M6 which are connected by common gates, a seventh MOS transistor M7, a second resistor R2, a first transistor Q1, a second transistor Q2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

Specifically, the drain electrode of the fifth MOS transistor M5 is connected to the current mirror circuit 10 and the detection circuit, and the gate electrode and the drain electrode of the sixth MOS transistor M6 are shorted and connected to the gate electrode of the seventh MOS transistor M7 and the current mirror circuit 10. The collector of the first transistor Q1 is connected with the source of the fifth MOS transistor M5, the base of the first transistor Q1 is connected with the base of the second transistor Q2, the collector of the second transistor Q2 is connected with the source of the sixth MOS transistor M6 and the detection circuit, and the connection points of the collector of the second transistor Q2, the source of the sixth MOS transistor and the detection circuit form a second detection point BGOK_N. An emitter of the first triode Q1 is connected with a first end of the third resistor R3, an emitter of the second triode Q2 is connected with a second end of the third resistor R3 and a first end of the fourth resistor R4, and a second end of the fourth resistor R4 is grounded. The drain electrode of the seventh MOS tube M7 is connected with the first end of the second resistor R2, the second end of the second resistor R2 is connected with the power supply voltage AVDD, the source electrode of the seventh MOS tube M7 is connected with the base electrode of the second triode Q2, the first end of the fifth resistor R5 and the band gap reference output end, and the second end of the fifth resistor R5 is grounded.

The second resistor R2, the sixth MOS transistor M6, the seventh MOS transistor M7, the second transistor Q2, and the fifth resistor R5 form a feedback loop for clamping the voltage of the second detection point bgok_n. Whether the feedback loop and the current mirror circuit 10 are established is a very critical factor in determining whether the bandgap reference voltage VBG is established.

As can be seen from the above description, the connection point of the second end of the first resistor R1, the gate of the third MOS transistor M3, and the drain of the fifth MOS transistor is the first detection point bgok_p. The connection point between the source of the sixth MOS transistor M6 and the collector of the second transistor Q2 is the second detection point bgok_n. By using the connection point of the source electrode of the sixth MOS transistor M6 and the collector electrode of the second transistor Q2 as the second detection point bgok_n, the range of the power supply voltage AVDD is 2.7V or more and is wider on the premise of satisfying the measurement accuracy. In other embodiments, the gate of the sixth MOS transistor M6 may be selected as the second detection point bgok_n, and the range of the power supply voltage AVDD is more than 4V on the premise of satisfying the measurement accuracy.

As shown in fig. 1, the detection circuit includes a comparator COMP, and a first input terminal and a second input terminal of the comparator COMP 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 inputs of the comparator COMP may be swapped.

As shown in fig. 1, a first control end of the start control circuit is connected to a first detection point bgok_p, a second control end of the start control circuit is connected to an enable end of the comparator COMP, and the comparator COMP is prevented from outputting an error result when currents on two branches connected to a first input end and a second input end of the comparator COMP are 0 by controlling the enable end of the comparator COMP.

In the initial stage of the 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 level through the first control terminal, so that the voltage of the first detection point bgok_p is smaller than the voltage of the second detection point bgok_n. When the bandgap reference voltage VBG is not established, the voltage at the first detection point bgok_p and the voltage at the second detection point bgok_n both rise with the power supply voltage AVDD. At this time, the first current I1 flowing through the first MOS transistor M1 and the third MOS transistor M3 is greater than the second current I2 flowing through the second MOS transistor M2 and the fourth MOS transistor M4.

The voltage of the corresponding first detection point bgok_p is:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage at the second detection point bgok_n is:

VBGOK_N＝AVDD-I2×(Rds2+Rds4)-Vgs6

in the initial stage of the establishment of the bandgap reference voltage VBG, the second MOS transistor M2 and the fourth MOS transistor M4 are regarded as switching transistors, rds2+rds4< R1, the voltage of the first detection point bgok_p is smaller than the voltage of the second detection point bgok_n, and at this time, the bandgap reference establishment signal bg_ok output by the output end of the comparator COMP is "0".

With the establishment of the bandgap reference voltage VBG, if the voltage of the first detection point bgok_p is greater than or equal to the voltage of the second detection point bgok_n, the surface bandgap reference voltage VBG is already established. In the present embodiment, the bandgap reference voltage VBG is established when the voltage of the first detection point bgok_p is greater than or equal to the voltage of the second detection point bgok_n. However, when the voltage at the first detection point bgok_p is equal to the voltage at the second detection point bgok_n, the bandgap reference voltage VBG is not sufficiently established, and the bandgap reference voltage VBG is established to the critical point for the reasons of safe operation of the comparator COMP, anti-interference, and the like. Only when the voltage of the first detection point bgok_p is greater than the voltage of the second detection point bgok_n, it indicates that the bandgap reference voltage VBG is sufficiently established.

If the voltage of the first detection point bgok_p is equal to the voltage of the second detection point bgok_n, the bandgap reference voltage VBG is established to the critical point, i.e.:

AVDD-I1×R1-|Vgs1|＝AVDD-I2×(Rds2+Rds4)-Vgs6

note Δvgs=vgs 6- |vgs1| can be obtained:

R1＝I2/I1×(Rds2+Rds4)+ΔVgs/I1

the value of avgs varies little and can be considered a constant value. By setting the sixth MOS transistor M6 and the first MOS transistor M1 to different aspect ratios and combining the first current I1 to be larger than the second current I2, Δvgs >0.

If the voltage of the first detection point bgok_p is greater than the voltage of the second detection point bgok_n, the feedback loop of the bandgap reference generating circuit is established, and the voltage of the first detection point bgok_p is:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage at the second detection point bgok_n is:

VBGOK_N＝VBG+Vgs7-Vgs6

it can be seen that the expression of the voltage at the first detection point bgok_p is unchanged when the bandgap reference voltage VBG is established, compared to the bandgap reference voltage VBG established to the critical point, and the voltage at the second detection point bgok_n is finally clamped to be approximately equal to 1.2V. When the voltage of the first detection point bgok_p is greater than the voltage of the second detection point bgok_n, the bandgap reference establishment signal bg_ok output by the output terminal of the comparator COMP is "1".

Regardless of the safe operation of the comparator COMP and the anti-interference reasons, the first current I1 when the bandgap reference voltage VBG is established is equal to the second current I2, r1=i2/i1× (rds2+rds4) +Δvgs/I1, which can be reduced to r1=rds2+rds4+Δvgs/I1, Δvgs/I1 being constant.

In the above expressions, AVDD is the power supply voltage, I1 is the first current flowing through the first MOS transistor M1 and the third MOS transistor M3, I2 is the second current flowing through the second MOS transistor M2 and the fourth MOS transistor M4, R1 is the resistance of the first resistor R1, vgs1 is the voltage between the gate and the source of the first MOS transistor M1, rds2 is the resistance between the drain and the source of the second MOS transistor M2, rds4 is the resistance between the drain and the source of the fourth MOS transistor M4, vgs6 is the voltage between the gate and the source of the sixth MOS transistor M6, VBG is the bandgap reference voltage, and Vgs7 is the voltage between the gate and the source of the seventh MOS transistor M7.

As shown in fig. 2, in the process of establishing the bandgap reference voltage VBG, the sum of the resistance Rds2 between the drain and the source of the second MOS transistor M2 and the resistance Rds4 between the drain and the source of the fourth MOS transistor M4 varies with the sum of the voltage Vds2 between the drain and the source of the second MOS transistor M2 and the voltage Vds4 between the drain and the source of the fourth MOS transistor M4.

When the sum of the voltage Vds2 and the voltage Vds4 is smaller than 200uV, the second MOS transistor M2 and the fourth MOS transistor M4 are in the cut-off state, and the sum of the resistance Rds2 and the resistance Rds4 is very large. Along with the increase of the sum of the voltage Vds2 and the voltage Vds4, the second MOS transistor M2 and the fourth MOS transistor M4 enter the linear region. Because the voltage Vgs2 between the gate and the source of the second MOS transistor M2 and the voltage Vgs4 between the gate and the source of the fourth MOS transistor M4 are only about 1V, the sum of the linear resistance values of the second MOS transistor M2 and the fourth MOS transistor M4 is 10 k-20 kΩ, after the sum of the voltage Vds2 and the voltage Vds4 is greater than 0.2V, the second MOS transistor M2 and the fourth MOS transistor M4 enter a saturation region, and the sum of the resistance Rds2 and the resistance Rds4 increases sharply.

As shown in fig. 3, in the process of establishing the bandgap reference voltage VBG, the first current I1 flowing through the first MOS transistor M1 and the third MOS transistor M3 and the second current I2 flowing through the second MOS transistor M2 and the fourth MOS transistor M4 may change along with the sum of the voltage Vds2 between the drain and the source of the second MOS transistor M2 and the voltage Vds4 between the drain and the source of the fourth MOS transistor M4.

In the initial stage of the establishment of the band gap reference voltage VBG, the starting control circuit pulls down the voltage of the first detection point BGOK_P, so that the first current I1 is rapidly increased, and after the starting control circuit is closed, the first current I1 and the second current I2 are gradually close to each other and are finally equal through the adjustment of the current mirror circuit and the feedback loop.

As shown in fig. 4, this embodiment also discloses a method for detecting a band gap reference setup signal, where the method is based on the band gap reference circuit, and the method includes:

s1, a connection point of the bandgap reference generating circuit 20 and the current mirror circuit 10 is selected as a first detection point BGOK_P.

S2, a connection point in the bandgap reference generating circuit 20 is selected as a second detection point BGOK_N, and the voltage of the selected second detection point BGOK_N is clamped by the feedback loop of the bandgap reference generating circuit when the bandgap reference voltage VBG is established.

S3, controlling the voltage of a first detection point BGOK_P at the initial stage of establishing the band gap reference voltage VBG; specifically, the voltage of the first detection point bgok_p is pulled down to a low voltage level, so that the voltage of the first detection point bgok_p is smaller than the voltage of the second detection point bgok_n.

S4, comparing the voltages of the first detection point BGOK_P and the second detection point BGOK_N to judge the state of the feedback loop;

s5, representing the state of the band gap reference circuit by using the feedback loop state, specifically judging whether the band gap reference voltage VBG is established, if the voltage of the first detection point BGOK_P is greater than or equal to the voltage of the second detection point BGOK_N, the band gap reference voltage VBG is established. If the voltage of the first detection point BGOK_P is smaller than the voltage of the second detection point BGOK_N, the bandgap reference voltage VBG is not established. In the present embodiment, if the voltage of the first detection point bgok_p is equal to the voltage of the second detection point bgok_n, it indicates that the bandgap reference voltage VBG is established to the critical point. If the voltage of the first detection point BGOK_P is greater than the voltage of the second detection point BGOK_N, the bandgap reference voltage VBG is fully established.

From the above technical scheme, the invention has the following beneficial effects:

the invention uses the connection point of the current mirror circuit and the band gap reference generating circuit as a first detection point, and uses the connection point of the voltage clamped by the feedback loop of the band gap reference generating circuit when the band gap reference voltage is established as a second detection point. The first detection point is used as a relative reference point, the second detection point can rise along with the rising of the power supply voltage before the band gap feedback loop is not established, the second detection point can be kept unchanged by clamping the band gap reference voltage in the feedback loop after the establishment of the feedback loop is completed, the detection circuit compares the voltages of the first detection point and the second detection point to determine whether the feedback loop is established or not, and a band gap reference establishment signal is output to determine whether the band gap reference voltage is established or not, so that signals can be accurately and timely output in various scenes.

The invention can correctly send out the band-gap reference establishment signal with established band-gap reference voltage within the range of 0.27uV/us to 5.5V/us in the system power-on speed, has short sending delay, does not need an additional auxiliary circuit, has simple implementation mode and saves power consumption and cost.

The invention can be used in a quite wide power supply voltage range, and the applicable minimum power supply voltage is slightly higher than the band gap voltage plus the threshold voltage of two MOS tubes.

The invention has clear logic and convenient realization, can accelerate the power-on speed of the system, and can also timely and rapidly send out signals to protect the system when the power supply is abnormally powered off or the system is abnormally.

The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (10)

1. A bandgap reference circuit based on feedback control, comprising:

a bandgap reference generating circuit for generating a bandgap reference voltage;

a current mirror circuit for supplying a current to the bandgap reference generating circuit;

the bandgap reference circuit is characterized by further comprising:

the current mirror circuit is connected with the band gap reference generating circuit, and the connection point forms a first detection point;

a second detection point is formed in the band-gap reference generating circuit, and the voltage of the second detection point is clamped by a feedback loop of the band-gap reference generating circuit when the band-gap reference voltage is established;

the starting control circuit is used for controlling the voltage of the first detection point; and

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 band gap reference establishment signal for judging whether the band gap reference voltage is established or not.

2. The feedback control-based bandgap reference circuit of claim 1, wherein said start-up control circuit is configured to pull down the voltage at the first detection point to a low potential at an initial stage of said bandgap reference voltage establishment.

3. The feedback control-based bandgap reference circuit of claim 1, wherein said detection circuit outputs a bandgap reference setup signal that said bandgap reference voltage has been established when the voltage at the first detection point is greater than or equal to the voltage at the second detection point.

4. The feedback control-based bandgap reference circuit of claim 1, wherein said current mirror circuit comprises first and second MOS transistors connected in common gate, third and fourth MOS transistors connected in common gate, and a first resistor;

the drain electrode of the first MOS tube is connected with the source electrode of the third MOS tube, the drain electrode of the second MOS tube is connected with the source electrode of the fourth MOS tube, the source electrodes of the first MOS tube and the second MOS tube are connected with the power supply voltage, the first end of the first resistor is connected with the grid electrode of the first MOS tube and the drain electrode of the third MOS tube, the second end of the first resistor is connected with the grid electrode of the third MOS tube, the detection circuit and the band gap reference generation circuit, the connection points of the second end of the first resistor, the grid electrode of the third MOS tube and the detection circuit form a first detection point, and the drain electrode of the fourth MOS tube is connected with the band gap reference generation circuit.

5. The feedback control-based bandgap reference circuit of claim 1, wherein said bandgap reference generation circuit comprises fifth and sixth MOS transistors, seventh MOS transistor, second resistor, first transistor, second transistor, third resistor, fourth resistor and fifth resistor connected in common gate;

the drain electrode of the fifth MOS tube is connected with the current mirror circuit and the detection circuit, the grid electrode and the drain electrode of the sixth MOS tube are in short circuit and are connected with the grid electrode and the current mirror circuit of the seventh MOS tube, the collector electrode of the first MOS tube is connected with the source electrode of the fifth MOS tube, the base electrode of the first MOS tube is connected with the base electrode of the second MOS tube, the collector electrode of the second MOS tube is connected with the source electrode of the sixth MOS tube and the detection circuit, the connection points of the collector electrode of the second MOS tube, the source electrode of the sixth MOS tube and the detection circuit form a second detection point, the emitter electrode of the first MOS tube is connected with the first end of the third resistor, the emitter electrode of the second MOS tube is connected with 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 electrode of the seventh MOS tube is connected with the first end of the second resistor, the second end of the second resistor is connected with the power supply voltage, the source electrode of the seventh MOS tube is connected with the first end of the second MOS tube, the fifth resistor and the band gap voltage output end, and the fifth resistor is grounded.

6. The feedback control-based bandgap reference circuit of claim 5, wherein at an initial stage of said bandgap reference voltage establishment, a first detection point voltage is less than a second detection point voltage, said first detection point voltage being:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage of the second detection point is as follows:

VBGOK_N＝AVDD-I2×(Rds2+Rds4)-Vgs6

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 a critical point, namely:

AVDD-I1×R1-|Vgs1|＝AVDD-I2×(Rds2+Rds4)-Vgs6

note Δvgs=vgs 6- |vgs1| can be obtained:

R1＝I2/I1×(Rds2+Rds4)+ΔVgs/I1

if the voltage of the first detection point is greater than the voltage of the second detection point, the feedback loop of the band gap reference generating circuit is established, and the voltage of the first detection point is:

VBGOK_P＝AVDD-I1×R1-|Vgs1|

the voltage of the second detection point is as follows:

VBGOK_N＝VBG+Vgs7-Vgs6

wherein AVDD is a power supply voltage, I1 is a first current flowing through the first MOS transistor and the third MOS transistor, I2 is a second current flowing through the second MOS transistor and the fourth MOS transistor, R1 is a resistance value of the first resistor, vgs1 is a voltage between the gate and the source of the first MOS transistor, rds2 is a resistance between the drain and the source of the second MOS transistor, rds4 is a resistance between the drain and the source of the fourth MOS transistor, vgs6 is a voltage between the gate and the source of the sixth MOS transistor, VBG is a bandgap reference voltage, and Vgs7 is a voltage between the gate and the source of the seventh MOS transistor.

7. The feedback control-based bandgap reference circuit of claim 1, wherein said detection circuit comprises a comparator, a first input terminal and a second input terminal of said comparator being connected to a first detection point and a second detection point, respectively, and said start-up control circuit enables control of said comparator based on said bandgap reference voltage.

8. A method for detecting a bandgap reference build signal, the method comprising:

selecting a connection point of the band gap reference generating circuit and the current mirror circuit as a first detection point;

selecting a connection point in the band-gap reference generating circuit as a second detection point, wherein the voltage of the selected second detection point is clamped by a feedback loop of the band-gap reference generating circuit when the band-gap reference voltage is established;

controlling the voltage of the first detection point at the initial stage of the establishment of the band gap reference voltage;

comparing the voltages of the first detection point and the second detection point to judge the feedback loop state;

the feedback loop state is used to characterize whether the bandgap reference voltage is established.

9. The method of detecting a bandgap reference building signal according to claim 8, wherein controlling the voltage at the first detection point at an initial stage of bandgap reference voltage building comprises:

and pulling down the voltage of the first detection point to a low potential so that the voltage of the first detection point is smaller than the voltage of the second detection point.

10. The method of detecting a bandgap reference build signal according to claim 8, wherein comparing voltages at the first detection point and the second detection point to determine whether the bandgap reference voltage is built up comprises:

if the voltage of the first detection point is greater than or equal to the voltage of the second detection point, the band gap reference voltage is established;

if the voltage of the first detection point is smaller than the voltage of the second detection point, the band gap reference voltage is not established.

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