CN117539320A - Band gap reference circuit - Google Patents

Abstract

The invention discloses a band gap reference circuit, which relates to the field of circuits and comprises a reference voltage generation module, a comparison module and a reference voltage trimming module. The reference voltage generation module generates a reference voltage including a positive temperature coefficient voltage and a negative temperature coefficient voltage. When the environmental factors change to cause the reference voltage to change, the trimming signal output by the comparison module also changes, and the reference voltage trimming module adjusts the resistance value of the resistor affecting the voltage value of the positive temperature coefficient voltage based on the trimming signal, so that the positive temperature coefficient voltage is adjusted until the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage, namely the reference voltage is restored to be within a preset reference voltage range under the zero temperature coefficient, so that the actual reference voltage is always close to the zero temperature coefficient, and the automatic trimming of the reference voltage is realized.

Description

Band gap reference circuit

Technical Field

The invention relates to the field of circuits, in particular to a band gap reference circuit.

Background

The bandgap reference circuit is generally used for providing a reference voltage for a subsequent circuit, and the precision and stability of the reference voltage play a vital role in the performance of the subsequent circuit. The precision of the reference voltage is closely related to the temperature coefficient of the reference voltage, the band gap reference circuit in the related art can generate a positive temperature coefficient voltage and a negative temperature coefficient voltage through a transistor, and the zero temperature coefficient reference voltage is obtained by adjusting the ratio between the positive temperature coefficient voltage and the negative temperature coefficient voltage. However, the negative temperature coefficient voltage generated by the transistor and the negative temperature coefficient voltage do not have a linear change relation with temperature, and the reference voltage cannot always be zero temperature coefficient voltage when environmental factors such as temperature or voltage change.

Disclosure of Invention

The invention aims to provide a band-gap reference circuit, which can automatically adjust the reference voltage under the condition that the reference voltage is changed due to the change of environmental factors, so that the reference voltage actually output by the band-gap reference circuit is always close to zero temperature coefficient.

In order to solve the technical problems, the invention provides a band gap reference circuit, which comprises a reference voltage generating module, a comparing module and a reference voltage trimming module;

the reference voltage generation module is used for generating reference voltages, wherein the reference voltages comprise positive temperature coefficient voltages and negative temperature coefficient voltages;

the comparison module is used for comparing the reference voltage with the reference voltage and outputting a trimming signal based on a comparison result;

the reference voltage trimming module is used for adjusting the resistance value of a resistor related to the voltage value of the positive temperature coefficient voltage in the reference voltage generating module based on the trimming signal so as to adjust the positive temperature coefficient voltage until the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage is maintained within a preset reference voltage range under a zero temperature coefficient.

Optionally, the comparison module includes a logic module and M comparators, where M is a positive integer;

the first input end of each comparator is connected with the reference voltage output end of the reference voltage generation module, the second input ends of the M comparators are sequentially input with M reference voltages, the reference voltages are different from each other, and the output end of each comparator is connected with the input end of the logic module;

the logic module is used for generating the trimming signal with M bits based on the output signals of the comparators.

Optionally, the reference voltage generating module includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first transistor, a second transistor and a first operational amplifier, and the fourth resistor includes at least M first trimming resistors connected in series;

the first end of the first resistor and the first end of the second resistor are connected with a power supply, the second end of the first resistor is connected with the first input end of the first operational amplifier and the first end of the first transistor, and the second end of the second resistor is connected with the second input end of the first operational amplifier and the first end of the second transistor;

the second end of the first transistor and the second end of the second transistor are connected, the connected common end is connected with the output end of the first operational amplifier, the third end of the first transistor is connected with the first end of the third resistor, the second end of the third resistor and the third end of the second transistor are connected with the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

Optionally, the reference voltage trimming module includes M first controllable switches;

the first ends of the M first controllable switches are respectively connected with M public ends which are mutually connected with the first trimming resistors, the second ends of the M first controllable switches are grounded, and the first bit signal to the M bit signal of the trimming signal are sequentially input from the control end of the first controllable switch to the control end of the M first controllable switch.

Optionally, the comparator is specifically configured to output a first level when the reference voltage is smaller than the reference voltage, and output a second level when the reference voltage is greater than the reference voltage, where the first level is a level for controlling the first controllable switch to be turned on, and the second level is a level for controlling the first controllable switch to be turned off;

the logic module is specifically configured to generate the trimming signals based on the outputs of the M comparators, and the trimming signals are configured to enable the first trimming resistors corresponding to the reference voltage closest to the reference voltage among all the reference voltages greater than the reference voltage to be connected between the second end of the third resistor and ground by controlling the switching states of the first controllable switches.

Optionally, the reference voltage generating module includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second operational amplifier, a first MOS transistor, a third transistor, and a fourth transistor, where the eighth resistor includes M second trimming resistors connected in series;

the first end of the third transistor and the first end of the fourth transistor are grounded, the second end of the third transistor is connected with the second end of the fourth transistor and the connected common ground is grounded, the third end of the third transistor is connected with the first end of the fifth resistor and the connected common end of the third transistor is connected with the first input end of the second operational amplifier, the third end of the fourth transistor is connected with the first end of the seventh resistor, and the second end of the seventh resistor is connected with the first end of the sixth resistor and the connected common end of the sixth resistor is connected with the second input end of the second operational amplifier;

the output end of the second operational amplifier is connected with the control end of the first MOS tube, the first end of the first MOS tube is connected with a power supply, the second end of the first MOS tube is connected with the second end of the eighth resistor, and the second end of the fifth resistor and the second end of the sixth resistor are connected with the first end of the eighth resistor.

Optionally, the reference voltage trimming module includes M second controllable switches;

the first ends of the M second controllable switches are respectively connected with M public ends of the second trimming resistors, the second ends of the M second controllable switches are connected with each other, the voltage of the connecting point is used as the reference voltage, and the control ends of the first second controllable switches to the control ends of the Mth second controllable switches sequentially input first bit signals to Mth bit signals of the trimming signals.

Optionally, the comparator is specifically configured to output a first level when the reference voltage is smaller than the reference voltage, and output a second level when the reference voltage is greater than the reference voltage, where the first level is a level for controlling the first controllable switch to be turned on, and the second level is a level for controlling the first controllable switch to be turned off;

the logic module is specifically configured to generate the trimming signal based on the outputs of the M comparators, and the trimming signal is configured to adjust a resistance value of a resistor related to a voltage value of the positive temperature coefficient voltage by controlling a switching state of each of the second controllable switches.

Optionally, the device further comprises a reference voltage generating module for generating M reference voltages, wherein the reference voltage generating module comprises a reference voltage source and a plurality of voltage dividing resistors;

and the voltage dividing resistors are connected in series, two ends of the circuit after the series connection are respectively connected with the output end of the reference voltage source and the ground, and the voltages of M public ends of the voltage dividing resistors which are connected with each other are used as M reference voltages.

Optionally, the voltage regulator further comprises a low dropout linear voltage regulator arranged between the output end of the reference voltage source and the voltage dividing resistor.

The beneficial effects of the application lie in that provide a band gap reference circuit, including reference voltage generation module, comparison module and reference voltage trimming module. The reference voltage generation module generates a reference voltage including a positive temperature coefficient voltage and a negative temperature coefficient voltage. When the environmental factors change to cause the reference voltage to change, the trimming signal output by the comparison module also changes, and the reference voltage trimming module adjusts the resistance value of the resistor affecting the voltage value of the positive temperature coefficient voltage based on the trimming signal, so that the positive temperature coefficient voltage is adjusted until the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage, namely the reference voltage is restored to be within a preset reference voltage range under the zero temperature coefficient, so that the actual reference voltage is always close to the zero temperature coefficient, and the automatic trimming of the reference voltage is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the prior art and the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a bandgap reference circuit provided herein;

FIG. 2 is a first circuit diagram of a bandgap reference circuit provided herein;

FIG. 3 is a second circuit diagram of a bandgap reference circuit provided herein;

FIG. 4 is a circuit diagram of a comparison module and a reference voltage generation module in a bandgap reference circuit provided by the present application;

fig. 5 is a circuit diagram of a comparator in a bandgap reference circuit provided in the present application.

Detailed Description

The core of the invention is to provide a band gap reference circuit, which can automatically adjust the reference voltage under the condition that the reference voltage is changed due to the change of environmental factors, so that the reference voltage actually output by the band gap reference circuit is always close to zero temperature coefficient.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a bandgap reference circuit provided in the present application, where the bandgap reference circuit includes a reference voltage generating module 1, a comparing module 2, and a reference voltage trimming module 3;

the reference voltage generation module 1 is used for generating a reference voltage, wherein the reference voltage comprises a positive temperature coefficient voltage and a negative temperature coefficient voltage;

the comparison module 2 is used for comparing the reference voltage with the reference voltage and outputting a trimming signal based on a comparison result;

the reference voltage trimming module 3 is configured to adjust a resistance value of a resistor related to a voltage value of the positive temperature coefficient voltage in the reference voltage generating module 1 based on the trimming signal, so as to adjust the positive temperature coefficient voltage until a sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage is maintained within a preset reference voltage range under a zero temperature coefficient.

The invention aims to provide a band gap reference circuit capable of automatically trimming reference voltage, so that the reference voltage output by a reference voltage generating module 1 is automatically adjusted to be within a preset reference voltage range under the condition that the reference voltage output by the reference voltage generating module 1 is changed due to environmental factors such as temperature, voltage and pressure, and the like, so that the automatic trimming of the temperature coefficient of the reference voltage is realized. It should be noted that, a voltage value when the temperature coefficient of the reference voltage generated by the reference voltage generating module 1 in the current environment is zero temperature coefficient may be predetermined, and a preset reference voltage range may be determined according to the voltage value, so that the temperature coefficient of the reference voltage is close to zero temperature coefficient when the reference voltage falls within the preset reference voltage range.

Specifically, the reference voltage generating module 1 in the present application is configured to generate a reference voltage, where the reference voltage includes a positive temperature coefficient voltage and a negative temperature coefficient voltage, and the reference voltage with zero temperature coefficient in the current environment is formed by adjusting a ratio between the positive temperature coefficient voltage and the negative temperature coefficient voltage. For example, the reference voltage generating module 1 generates the positive temperature coefficient voltage and the negative temperature coefficient voltage by using two transistors with emitter areas in a certain proportion, wherein the negative temperature coefficient voltage is the voltage VBE between the base and the emitter of the transistor, the positive temperature coefficient voltage is related to the emitter area ratio and the resistance value, and the proportion between the positive temperature coefficient voltage and the negative temperature coefficient voltage can be changed by adjusting the resistance value.

When environmental factors such as the ambient temperature, voltage and pressure of the bandgap reference circuit change, both the positive temperature coefficient voltage and the negative temperature coefficient voltage in the reference voltage change, so that the reference voltage generated by the reference voltage generating module 1 is no longer the zero temperature coefficient voltage, and the temperature coefficient of the reference voltage shifts. In order to realize automatic trimming of the temperature coefficient of the reference voltage, the application is provided with a comparison module 2 and a reference voltage trimming module 3 in the band gap reference circuit. The comparison module 2 compares the reference voltage with the reference voltage and outputs a trimming signal based on the comparison result. The reference voltage trimming module 3 adjusts the resistance value of the resistor related to the positive temperature coefficient voltage value in the reference voltage generating module 1 based on the trimming signal, thereby changing the voltage value of the positive temperature coefficient voltage. The negative temperature coefficient voltage in the reference voltage is influenced by environmental factors, and the voltage value of the negative temperature coefficient voltage is passively changed, so that the voltage value of the positive temperature coefficient voltage is actively adjusted, the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage is maintained within a preset reference voltage range under the zero temperature coefficient, and even if the reference voltage is always within the preset reference voltage range. When the reference voltage is within the preset reference voltage range, the temperature coefficient of the reference voltage is zero temperature coefficient, or very close to zero temperature coefficient.

It should be further noted that, the reference voltage generating module 1 in the present application may be a circuit that generates a positive temperature coefficient voltage and a negative temperature coefficient voltage for each type of pass transistor, and obtains the reference voltage by adjusting the ratio of the positive temperature coefficient voltage to the negative temperature coefficient voltage. The structure of the reference voltage generating module 1 includes, but is not limited to, a brookfaw structure and a kuijk structure.

In summary, the beneficial effects of the present application are that a bandgap reference circuit is provided, which includes a reference voltage generating module 1, a comparing module 2 and a reference voltage trimming module 3. The reference voltage generation module 1 generates a reference voltage including a positive temperature coefficient voltage and a negative temperature coefficient voltage. When the environmental factor changes to cause the reference voltage to change, the trimming signal output by the comparison module 2 also changes, and the reference voltage trimming module 3 adjusts the resistance value of the resistor affecting the voltage value of the positive temperature coefficient voltage based on the trimming signal, so as to adjust the positive temperature coefficient voltage until the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage, that is, the reference voltage is restored to be within the preset reference voltage range under the zero temperature coefficient, so that the actual reference voltage is always close to the zero temperature coefficient, and the automatic trimming of the reference voltage is realized.

As an alternative embodiment, the comparison module 2 includes a logic module and M comparators, where M is a positive integer;

the first input end of each comparator is connected with the reference voltage output end of the reference voltage generation module 1, the second input ends of the M comparators sequentially input M reference voltages, the reference voltages are different from each other, and the output ends of the comparators are connected with the input end of the logic module;

the logic module is used for generating a trimming signal with M bits based on the output signals of the comparators.

Referring to fig. 4, fig. 4 is a circuit diagram of a comparison module and a reference voltage generation module in a bandgap reference circuit provided by the present application. In this embodiment, the comparison module 2 includes a logic module and M comparators, wherein a first input terminal of each comparator inputs the reference voltage VBG output by the reference voltage output terminal of the reference voltage generation module 1, a second input terminal of each comparator sequentially inputs each reference voltage (Vref 1, vref2 to VrefM), and an output terminal of each comparator outputs each comparison signal (Trim SEL0, trim SEL1 to Trim SEL M-1). The level of the comparison signal output by the comparator is either a high level or a low level. The logic module integrates the comparison signals output by the comparators into trimming signals, and the bits of the trimming signals are M bits. The reference voltage trimming module 3 adjusts the resistance value of the resistor affecting the voltage value of the positive temperature coefficient voltage based on the trimming signal, thereby adjusting the positive temperature coefficient voltage, and finally adjusting the reference voltage actually output by the reference voltage generating module 1 to be within the preset reference voltage range, so as to realize trimming of the temperature coefficient of the reference voltage.

The structure of the bandgap reference circuit and the principle of implementing automatic trimming of temperature coefficient provided in the present application will be described below by taking the reference voltage generation module 1 with a brookaw structure as an example.

As an alternative embodiment, the reference voltage generating module 1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor Q1, a second transistor Q2, and a first operational amplifier, and the fourth resistor R4 includes at least M first trimming resistors connected in series;

the first end of the first resistor R1 and the first end of the second resistor R2 are connected with the power supply VDD, the second end of the first resistor R1 is connected with the first input end of the first operational amplifier and the first end of the first transistor Q1, and the second end of the second resistor R2 is connected with the second input end of the first operational amplifier and the first end of the second transistor Q2;

the second end of the first transistor Q1 and the second end of the second transistor Q2 are connected, the connected common end is connected with the output end of the first operational amplifier, the third end of the first transistor Q1 is connected with the first end of the third resistor R3, the second end of the third resistor R3 and the third end of the second transistor Q2 are connected with the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is grounded.

Referring to fig. 2, fig. 2 is a first circuit diagram of a bandgap reference circuit provided in the present application. The ratio of emitter areas of the first transistor Q1 and the second transistor Q2 is N:1, after voltage clamping and negative feedback are performed on the two transistors by the first operational amplifier, the voltage and the current of the collector of the first transistor Q1 and the collector of the second transistor Q2 are equal. IQ 1=iq 2=vt (lnN)/R3, where IQ1 is the current of the collector of the first transistor Q1, IQ2 is the current of the collector of the second transistor Q2, VT is a known thermal voltage, N is the ratio of the emitter areas of the first transistor Q1 and the second transistor Q2, and R3 is the resistance of the third resistor. In this embodiment, the voltage at the output end of the first operational amplifier in the reference voltage generating module 1 is the reference voltage, vbg=vbe2+2×vt (lnN) ×r4/R3, where VBG is the reference voltage, VBE2 is the voltage between the base and the emitter of the second transistor Q2, and R4 is the resistance of the fourth resistor. It can be seen that by selecting the appropriate N, fourth resistor R4, and third resistor R3, a reference voltage with zero temperature coefficient in the current environment can be obtained, and the voltage value of the reference voltage can be adjusted by changing the resistance value of fourth resistor R4. The fourth resistor R4 includes at least M first trimming resistors connected in series, and the resistance value of the fourth resistor R4 can be changed by adjusting the connection state of each first trimming resistor in the reference voltage generating module 1, so as to adjust the voltage value of the positive temperature coefficient voltage. In addition, each first trimming resistor in the fourth resistor R4 can be a resistor with the same resistance value, so that the operation is easier. As an alternative embodiment, the reference voltage trimming module 3 includes M first controllable switches M1;

the first ends of the M first controllable switches M1 are respectively connected with M public ends of the first trimming resistors, which are mutually connected, the second ends of the M first controllable switches M1 are grounded, and the first bit signals to the M bit signals of the trimming signals are sequentially input from the control end of the first controllable switch M1 to the control end of the M first controllable switch M1.

On the basis of the above embodiment, the reference voltage trimming module 3 includes M first controllable switches M1, where a first end of each first controllable switch M1 is connected to a common end of each first trimming resistor in the fourth resistor R4, and a second end of each first controllable switch M1 is grounded. The reference voltage trimming module 3 uses the trimming signal output by the comparison module 2 as a control signal for controlling the on state of each first controllable switch M1, and determines whether the first trimming resistor is connected into the loop of the reference voltage generating module 1 by controlling the on state of the first controllable switch M1, thereby changing the resistance value of the fourth resistor R4 and further changing the voltage value of the positive temperature coefficient voltage. Each of the first controllable switches M1 may be an NMOS, a PMOS, or a transmission gate, which is not particularly limited in the present application.

As an alternative embodiment, the comparator is specifically configured to output a first level when the reference voltage is smaller than the reference voltage, and output a second level when the reference voltage is greater than the reference voltage, where the first level is a level for controlling the first controllable switch M1 to be turned on, and the second level is a level for controlling the first controllable switch M1 to be turned off;

the logic module is specifically configured to generate trimming signals based on the outputs of the M comparators, where the trimming signals are used to enable all first trimming resistors corresponding to a reference voltage closest to the reference voltage among the reference voltages greater than the reference voltage to be connected into a loop between the second end of the third resistor R3 and ground by controlling the switching states of the first controllable switches M1.

On the basis of the above-described embodiment, the reference voltage generated by the reference voltage generation module 1 is input to each comparator in the comparison module 2 module, and the reference voltage is compared with each reference voltage a plurality of times by the comparator. The comparator outputs a first level when the reference voltage is smaller than the reference voltage, and outputs a second level when the reference voltage is larger than the reference voltage, wherein the first level is a level for controlling the first controllable switch M1 to be turned on, and the second level is a level for controlling the first controllable switch M1 to be turned off. For example, when the first controllable switch M1 is an NMOS, the first level is a high level, and the second level is a low level.

The outputs of the comparators are operated by the logic modules to generate trimming signals, and the trimming signals ensure that only one first controllable switch M1 is conducted at a time so as to ensure that required first trimming resistors can be connected into a loop of the reference voltage generating module 1. For example, the voltage values of the first to mth reference voltages are sequentially decreased, and the reference voltage actually output by the current reference voltage generating module 1 is smaller than the third reference voltage and larger than the fourth reference voltage. At this time, the comparison signals output by the first comparator, the second comparator and the third comparator are all the first level which enables the first controllable switch M1 to be turned on. The reference voltage is closest to a third reference voltage, and the third reference voltage is formed by dividing the voltage of the first trimming resistor to the third first trimming resistor. In order to enable the first trimming resistor to the third first trimming resistor to be normally connected into the circuit, the logic module outputs trimming signals which only control the first controllable switch M1 corresponding to the third trimming resistor to be conducted. For example, the third bit of the trimming signal has a value of 1, and the rest bits have values of 0.

The reference voltage trimming module 3 controls the access state of the first trimming resistor in the fourth resistor R4 in the circuit based on the trimming signal generated by the comparison module 2, that is, changes the resistance value of the fourth resistor R4. When the environmental factors change, the trimming signal also changes, and the resistance value of the fourth resistor R4 is adjusted in real time, so that the voltage value of the positive temperature coefficient voltage is changed, the reference voltage is restored to the preset reference voltage range, and the reference voltage is ensured to have a lower temperature coefficient.

In other embodiments, the reference voltage generating module 1 may also be in a kuijk structure, and the structure of the bandgap reference circuit in this case and the principle of implementing automatic trimming of the temperature coefficient will be described below.

As an alternative embodiment, the reference voltage generating module 1 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a second operational amplifier, a first MOS transistor, a third transistor Q3, and a fourth transistor Q4, and the eighth resistor R8 includes M second trimming resistors connected in series;

the first end of the third transistor Q3 and the first end of the fourth transistor Q4 are grounded, the second end of the third transistor Q3 is connected with the second end of the fourth transistor Q4 and the connected common end is grounded, the third end of the third transistor Q3 is connected with the first end of the fifth resistor R5 and the connected common end is connected with the first input end of the second operational amplifier, the third end of the fourth transistor Q4 is connected with the first end of the seventh resistor R7, the second end of the seventh resistor R7 is connected with the first end of the sixth resistor R6 and the connected common end is connected with the second input end of the second operational amplifier;

the output end of the second operational amplifier is connected with the control end of the first MOS tube, the first end of the first MOS tube is connected with a power supply, the second end of the first MOS tube is connected with the second end of the eighth resistor R8, and the second end of the fifth resistor R5 and the second end of the sixth resistor R6 are connected with the first end of the eighth resistor R8.

Referring to fig. 3, fig. 3 is a second circuit diagram of a bandgap reference circuit provided in the present application, in this structure, vbg=vbe4+vt (lnN) (r6+r7+2×r8)/R7, wherein VBG is a reference voltage, VBE4 is a voltage between a base and an emitter of the fourth transistor Q4, VT is a known thermal voltage, a ratio of areas of the third transistor Q3 and the fourth transistor Q4 is N, and R6, R7 and R8 are a resistance of the sixth resistor, a resistance of the seventh resistor and a resistance of the eighth resistor in order. It can be seen that by selecting the appropriate N, sixth resistor R6, seventh resistor R7, and eighth resistor R8, the reference voltage with zero temperature coefficient in the current environment can be obtained, and the voltage value of the reference voltage can be adjusted by changing the resistance value of the eighth resistor R8. The eighth resistor R8 includes at least M second trimming resistors connected in series, each trimming resistor corresponding to an output voltage with a different temperature coefficient. The Trim SIG signal is adjusted to change the ratio of the resistors associated with the voltage value of the positive temperature coefficient voltage, thereby selecting a reference voltage that outputs a near zero temperature coefficient. In addition, each second trimming resistor in the eighth resistor R8 may be a resistor with the same resistance value, which is easier to operate.

As an alternative embodiment, the reference voltage trimming module 3 includes M second controllable switches M2;

the first ends of the M second controllable switches M2 are respectively connected with M public ends of the second trimming resistors, the second ends of the M second controllable switches M2 are connected with each other, the voltage of the connecting point is used as the reference voltage of selectable output, and the control ends of the first second controllable switches M2 to the control ends of the M second controllable switches M2 sequentially input first bit signals to M bit signals of trimming signals.

On the basis of the above embodiment, the reference voltage trimming module 3 includes M second controllable switches M2. The reference voltage trimming module 3 uses the trimming signals output by the comparison module 2 as control signals for controlling the conduction states of the second controllable switches M2, and determines the number of second trimming resistors corresponding to the actually output reference voltage by controlling the conduction states of the second controllable switches M2, so as to change the voltage value of the positive temperature coefficient voltage. Each of the second controllable switches M2 may be an NMOS, PMOS or a transmission gate, which is not particularly limited in the present application. That is, different from the reference voltage generating module 1 with the brookfaw structure, in this embodiment, each second trimming resistor is always connected to the loop of the reference voltage generating module 1, and in this embodiment, the reference voltage corresponds to the voltage division value of the second trimming resistor.

As an alternative embodiment, the comparator is specifically configured to output a first level when the reference voltage is smaller than the reference voltage, and output a second level when the reference voltage is greater than the reference voltage, where the first level is a level for controlling the first controllable switch M1 to be turned on, and the second level is a level for controlling the first controllable switch M1 to be turned off;

the logic module is specifically configured to generate a trimming signal based on the outputs of the M comparators, and the trimming signal is configured to adjust a resistance value of a resistor related to a voltage value of the positive temperature coefficient voltage by controlling a switching state of each of the second controllable switches M2.

On the basis of the above-described embodiment, the reference voltage generated by the reference voltage generation module 1 is input to each comparator in the comparison module 2, and the reference voltage is compared with each reference voltage a plurality of times by the comparator. The comparator outputs a first level when the reference voltage is smaller than the reference voltage, and outputs a second level when the reference voltage is larger than the reference voltage, wherein the first level is a level for controlling the first controllable switch M1 to be turned on, and the second level is a level for controlling the first controllable switch M1 to be turned off. For example, when the second controllable switch M2 is an NMOS, the first level is a high level, and the second level is a low level.

The output of each comparator is operated by a logic module to generate a trimming signal, and the trimming signal ensures that only one second controllable switch M2 is conducted at a time so as to ensure that the required partial voltage of each second trimming resistor is used as a reference voltage. For example, the voltage values of the first to mth reference voltages are sequentially decreased, and the reference voltage actually output by the current reference voltage generating module 1 is smaller than the third reference voltage and larger than the fourth reference voltage. At this time, the comparison signals output by the first comparator, the second comparator and the third comparator are all the first level for making the second controllable switch M2 conductive. The reference voltage is closest to the third reference voltage, and the third reference voltage is formed by dividing the voltage between the first second trimming resistor and the third second trimming resistor. In order to enable the first second trimming resistor to the third second trimming resistor to be normally connected into the circuit, the logic module outputs trimming signals which only control the second controllable switch M2 corresponding to the third trimming resistor to be conducted. For example, the third bit of the trimming signal has a value of 1, and the rest bits have values of 0.

The reference voltage trimming module 3 controls the output state of the voltage corresponding to each second trimming resistor in the eighth resistor R8 resistor string based on the trimming signal generated by the comparison module 2. When environmental factors change, the trimming signal also changes along with the change, and the resistance value of the eighth resistor R8 corresponding to the output reference voltage is adjusted in real time, so that the voltage value of the positive temperature coefficient voltage is changed, the reference voltage is restored to be within a preset reference voltage range, and the reference voltage is ensured to have a lower temperature coefficient.

As an alternative embodiment, the device further comprises a reference voltage generating module for generating M reference voltages, wherein the reference voltage generating module comprises a reference voltage source and a plurality of voltage dividing resistors;

the voltage dividing resistors are connected in series, two ends of the circuit after the series connection are respectively connected with the output end of the reference voltage source and the ground, and the voltages of M public ends of the voltage dividing resistors which are connected with each other are used as M reference voltages.

Referring to fig. 4, fig. 4 is a circuit diagram of a comparison module 2 and a reference voltage generation module in a bandgap reference circuit provided in the present application. In this embodiment, a reference voltage generating module is provided to provide each reference voltage, where the reference voltage generating module includes a reference voltage source and a plurality of voltage dividing resistors, and the connection relationship of the reference voltage generating module is shown in fig. 4. Preferably, as shown in fig. 4, a low dropout linear regulator can be further arranged between the output end of the reference voltage source and the voltage dividing resistor, so as to provide a stable reference voltage, and facilitate automatic trimming of the temperature coefficient of the reference voltage.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. In this specification, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, article or apparatus that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The band gap reference circuit is characterized by comprising a reference voltage generation module, a comparison module and a reference voltage trimming module;

the reference voltage generation module is used for generating reference voltages, wherein the reference voltages comprise positive temperature coefficient voltages and negative temperature coefficient voltages;

the comparison module is used for comparing the reference voltage with the reference voltage and outputting a trimming signal based on a comparison result;

the reference voltage trimming module is used for adjusting the resistance value of a resistor related to the voltage value of the positive temperature coefficient voltage in the reference voltage generating module based on the trimming signal so as to adjust the positive temperature coefficient voltage until the sum of the positive temperature coefficient voltage and the negative temperature coefficient voltage is maintained within a preset reference voltage range under a zero temperature coefficient.

2. The bandgap reference circuit of claim 1, wherein said comparison module comprises a logic module and M comparators, M being a positive integer;

the first input end of each comparator is connected with the reference voltage output end of the reference voltage generation module, the second input ends of the M comparators are sequentially input with M reference voltages, the reference voltages are different from each other, and the output end of each comparator is connected with the input end of the logic module;

the logic module is used for generating the trimming signal with M bits based on the output signals of the comparators.

3. The bandgap reference circuit of claim 2, wherein said reference voltage generation module comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first transistor, a second transistor and a first operational amplifier, said fourth resistor comprising at least M first trimming resistors connected in series;

the first end of the first resistor and the first end of the second resistor are connected with a power supply, the second end of the first resistor is connected with the first input end of the first operational amplifier and the first end of the first transistor, and the second end of the second resistor is connected with the second input end of the first operational amplifier and the first end of the second transistor;

the second end of the first transistor and the second end of the second transistor are connected, the connected common end is connected with the output end of the first operational amplifier, the third end of the first transistor is connected with the first end of the third resistor, the second end of the third resistor and the third end of the second transistor are connected with the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

4. The bandgap reference circuit of claim 3, wherein said reference voltage trimming module includes M first controllable switches;

the first ends of the M first controllable switches are respectively connected with M public ends which are mutually connected with the first trimming resistors, the second ends of the M first controllable switches are grounded, and the first bit signal to the M bit signal of the trimming signal are sequentially input from the control end of the first controllable switch to the control end of the M first controllable switch.

5. The bandgap reference circuit according to claim 4, wherein said comparator is specifically configured to output a first level when said reference voltage is less than said reference voltage and a second level when said reference voltage is greater than said reference voltage, said first level being a level that controls said first controllable switch to be on and said second level being a level that controls said first controllable switch to be off;

the logic module is specifically configured to generate the trimming signals based on the outputs of the M comparators, and the trimming signals are configured to enable the first trimming resistors corresponding to the reference voltage closest to the reference voltage among all the reference voltages greater than the reference voltage to be connected between the second end of the third resistor and ground by controlling the switching states of the first controllable switches.

6. The bandgap reference circuit of claim 2, wherein said reference voltage generation module comprises a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a second operational amplifier, a first MOS transistor, a third transistor and a fourth transistor, said eighth resistor comprising M second trimming resistors connected in series;

the first end of the third transistor and the first end of the fourth transistor are grounded, the second end of the third transistor is connected with the second end of the fourth transistor and the connected common ground is grounded, the third end of the third transistor is connected with the first end of the fifth resistor and the connected common end of the third transistor is connected with the first input end of the second operational amplifier, the third end of the fourth transistor is connected with the first end of the seventh resistor, and the second end of the seventh resistor is connected with the first end of the sixth resistor and the connected common end of the sixth resistor is connected with the second input end of the second operational amplifier;

the output end of the second operational amplifier is connected with the control end of the first MOS tube, the first end of the first MOS tube is connected with a power supply, the second end of the first MOS tube is connected with the second end of the eighth resistor, and the second end of the fifth resistor and the second end of the sixth resistor are connected with the first end of the eighth resistor.

7. The bandgap reference circuit of claim 6, wherein said reference voltage trimming module includes M second controllable switches;

the first ends of the M second controllable switches are respectively connected with M public ends of the second trimming resistors, the second ends of the M second controllable switches are connected with each other, the voltage of the connecting point is used as the reference voltage, and the control ends of the first second controllable switches to the control ends of the Mth second controllable switches sequentially input first bit signals to Mth bit signals of the trimming signals.

8. The bandgap reference circuit according to claim 7, wherein said comparator is specifically configured to output a first level when said reference voltage is less than said reference voltage and a second level when said reference voltage is greater than said reference voltage, said first level being a level that controls said first controllable switch to be on and said second level being a level that controls said first controllable switch to be off;

the logic module is specifically configured to generate the trimming signal based on the outputs of the M comparators, and the trimming signal is configured to adjust a resistance value of a resistor related to a voltage value of the positive temperature coefficient voltage by controlling a switching state of each of the second controllable switches.

9. The bandgap reference circuit of any one of claims 2 to 8, further comprising a reference voltage generation module for generating M of said reference voltages, said reference voltage generation module comprising a reference voltage source and a plurality of voltage dividing resistors;

and the voltage dividing resistors are connected in series, two ends of the circuit after the series connection are respectively connected with the output end of the reference voltage source and the ground, and the voltages of M public ends of the voltage dividing resistors which are connected with each other are used as M reference voltages.

10. The bandgap reference circuit of claim 9, further comprising a low dropout linear regulator disposed between an output of said reference voltage source and said voltage dividing resistor.