CN113342117A - Band-gap reference circuit for improving power supply rejection ratio by using feedback loop - Google Patents
Band-gap reference circuit for improving power supply rejection ratio by using feedback loop Download PDFInfo
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- CN113342117A CN113342117A CN202110563674.2A CN202110563674A CN113342117A CN 113342117 A CN113342117 A CN 113342117A CN 202110563674 A CN202110563674 A CN 202110563674A CN 113342117 A CN113342117 A CN 113342117A
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- resistor
- power supply
- operational amplifier
- rejection ratio
- supply rejection
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/567—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for temperature compensation
Abstract
The invention discloses a band-gap reference circuit for improving a power supply rejection ratio by using a feedback loop, and belongs to the technical field of analog integrated circuits. The bandgap reference circuit includes: the circuit comprises two NPN bipolar transistors Q1-Q2, six resistors R0-R5 and an operational amplifier. The operational amplifier adopts a differential input structure, divides the output of the operational amplifier by resistors, provides feedback voltage to the bases of NPN bipolar transistors Q1 and Q2, and simultaneously the feedback voltage is used as the output reference voltage of the band gap reference circuit. The resistances of the resistor R0 and the resistor R1 are equal, and the temperature coefficient and the accuracy of the reference voltage can be improved by adjusting the parallel number of the NPN bipolar transistor Q2 and the ratio of the resistor R3 to the resistor R2; by increasing the gain of the operational amplifier, the power supply rejection ratio of the output reference voltage can be effectively improved.
Description
Technical Field
The invention relates to an analog integrated circuit, in particular to a band-gap reference circuit for improving a power supply rejection ratio by utilizing a feedback loop.
Background
In an integrated circuit system, a reference voltage is often used, factors such as temperature drift of the reference voltage are required, the voltage variation range is as small as possible, and the suppression capability on power supply voltage ripples is as high as possible. For the temperature drift characteristic of the band-gap reference voltage, various curvature compensation technologies are available, such as segmented temperature compensation and second-order curvature compensation for the whole temperature range of circuit operation; in order to improve the rejection capability of the output reference voltage to the power supply voltage ripple, there are various schemes for increasing the power supply rejection ratio enhancement module. The scheme also makes the circuit structure more complicated, and the circuit area and the power consumption are increased. In order to improve the power supply rejection ratio of the output reference voltage in the traditional circuit, a power supply rejection ratio enhancing module is added in the circuit, so that the complexity, the area and the power consumption of the circuit are synchronously increased.
Disclosure of Invention
The purpose of the invention is as follows: the present invention is to solve the above problems, and an object of the present invention is to provide a bandgap reference circuit that improves a power supply rejection ratio by using a feedback loop, and improves the power supply rejection ratio of an output reference voltage while improving a gain of an operational amplifier; the invention does not need to additionally increase a power supply rejection ratio enhancement module, and has the advantages of simple structure and smaller chip area.
The technical scheme is as follows: a bandgap reference circuit, the circuit comprising:
the output end of the operational amplifier is connected in series with a resistor R4 and a resistor R5 between the output end of the operational amplifier and the ground, the base of a transistor Q1 is connected with the middle node of the resistor R4 and the resistor R5 which are connected in series, the middle node is an output reference voltage Vref node, the collector of a transistor Q1 is respectively connected with the second end of a resistor R1 and the reverse input end of the operational amplifier, the emitter of the transistor Q1 is grounded after being connected in series with the resistor R3, the base of a transistor Q2 is connected with the output reference voltage Vref node, the collector of a transistor Q2 is respectively connected with the second end of a resistor R0 and the same-direction input end of the operational amplifier, the emitter of the transistor Q2 is grounded after being connected in series with the resistor R2 and the resistor R3 in sequence, the first end of the resistor R0 is connected with VDD, and the first end of the resistor R1 is connected with VDD.
Further, the transistor Q1 is an NPN bipolar transistor.
Further, the transistor Q2 is an NPN bipolar transistor.
Further, the resistance value of the resistor R1 is equal to the resistance value of the resistor R2.
Further, changing the size or the number of parallel NPN bipolar transistors Q2, and changing the ratio of resistors R3 to R2 can be used to improve the temperature coefficient and accuracy of the reference voltage.
Further, the gain of the operational amplifier is increased for improving the power supply rejection ratio of the output reference voltage.
Further, the amplifier circuit is implemented using a BiCMOS process.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:
(1) the high-gain operational amplifier can ensure that the collector current of the NPN bipolar transistor Q1 and the collector current of the NPN bipolar transistor Q2 are equal as much as possible, so that the accuracy of the output reference voltage is improved;
(2) the power supply rejection ratio of the output reference voltage can be improved by increasing the gain of the operational amplifier;
(3) the circuit structure does not increase an additional power supply rejection ratio enhancement module, reduces the complexity of the circuit, reduces the circuit area and reduces the cost.
Drawings
Fig. 1 is a circuit diagram of the present invention.
Detailed Description
The invention is further elucidated with reference to the drawings and the embodiments.
The invention provides a band-gap reference circuit for improving the power supply rejection ratio by utilizing a feedback loop, which divides the output voltage of an operational amplifier and feeds the divided voltage back to the base of a bipolar transistor, thereby improving the power supply rejection ratio of the output reference voltage while improving the gain of the operational amplifier.
As shown in fig. 1, two NPN bipolar transistors Q1 and Q2, six resistors R0 to R5, and an operational amplifier; the same-direction input end of the operational amplifier is connected with the second end of the resistor R0 on one hand and the collector of the Q2 on the other hand, the reverse-direction input end of the operational amplifier is connected with the second end of the resistor R1 on the other hand and the collector of the Q1 on the other hand, the output end of the operational amplifier is connected with the ground through the resistor R4 and the resistor R5, the voltage at the connection part of the resistors R4 and R5 is the output voltage Vref of the circuit, and the operational amplifier is connected with the bases of NPN bipolar transistors Q1 and Q2; the base of Q1 is connected to the output voltage Vref, i.e. to the second terminal of a resistor R4 and to the first terminal of a resistor R5, the collector of Q1 is connected on the one hand to the supply voltage VDD via a resistor R1 and on the other hand to the inverting input of the operational amplifier, the emitter of Q1 is connected on the one hand to ground via a resistor R3 and on the other hand to the emitter of Q2 via a resistor R2; the base of Q2 is connected to the output voltage Vref of the circuit, i.e. to the second terminal of a resistor R4 and to the first terminal of a resistor R5, the collector of Q2 is connected on the one hand to the supply voltage VDD via a resistor R0 and on the other hand to the inverting input of the operational amplifier, and the emitter of Q2 is connected on the one hand to a resistor R3 via a resistor R2 and on the other hand to the emitter of Q1 via a resistor R2.
In order to make the currents flowing through the collector of Q1 and the collector of Q2 approximately equal, and the voltage values of the collector of Q1 and the collector of Q2 approximately equal, on one hand, the collector of Q1 and the collector of Q2 are respectively connected with VDD through a resistor R0 and a resistor R1 with equal resistance values, and on the other hand, the voltage difference between the collectors of Q1 and Q2 is ensured to be as small as possible through the 'virtual short' characteristic of the same-direction input end and the reverse-direction input end of the high-gain operational amplifier.
In order to make the ripple suppression capability of the output reference voltage of the circuit to the power supply VDD strong enough, the output voltage of the operational amplifier is divided by the resistors R4 and R5 and then fed back to the bases of Q1 and Q2 to form a feedback loop as shown in fig. 1.
Specifically, the detailed connection mode of each component is as follows:
the base of an NPN bipolar transistor Q1 is connected to the output voltage of the operational amplifier via a divided voltage Vref of resistors R4 and R5, the collector of Q1 is connected to the second terminal of resistor R1 on the one hand and to the inverting input terminal of the operational amplifier on the other hand, and the emitter of Q1 is connected to the first terminal of resistor R3 on the one hand and to the second terminal of resistor R2 on the other hand.
The base of an NPN bipolar transistor Q2 is connected with a Vref point of the output voltage of the operational amplifier after being divided by resistors R4 and R5, the collector of Q2 is connected with the second end of the resistor R0 on one hand, and the homodromous input end of the operational amplifier on the other hand, and the emitter of Q2 is connected with the first end of the resistor R2.
A first end of the resistor R0 is connected with VDD, and a second end of the resistor R0 is connected with the collector of Q2 on the one hand and the same-direction input end of the operational amplifier on the other hand;
a first end of the resistor R1 is connected with VDD, and a second end of the resistor R1 is connected with a collector of Q1 on the one hand and an inverting input end of the operational amplifier on the other hand;
a first end of the resistor R2 is connected with an emitter of the Q2, a second end of the resistor R2 is connected with a first end of the resistor R3 on one hand, and is connected with the emitter of the Q1 on the other hand;
a first end of the resistor R3 is connected with a second end of the resistor R2, an emitter of the Q1 and a resistor R3 to the ground;
the first end of the resistor R4 is connected with the output end of the operational amplifier, the voltage of the second end of the resistor R4 is the output reference voltage Vref, and the first end of the resistor R5 is connected with the bases of Q1 and Q2 on one hand;
the voltage of the first end of the resistor R5 is the output reference voltage Vref, and is connected with the base of Q1, the base of Q2 and the second end of the resistor R4; a second terminal of resistor R5 is connected to ground.
The same-direction input end of the operational amplifier is connected with the collector of the Q2 on one hand and is connected with the second end of the resistor R0 on the other hand; the inverting input end of the operational amplifier is connected with the collector of the Q1 on one hand and the second end of the resistor R1 on the other hand; the output of the operational amplifier is connected to a first terminal of a resistor R4.
The working principle of the band-gap reference circuit is as follows:
first, the circuit obtains the output reference voltage Vref with zero temperature coefficient by superimposing two voltages with opposite temperature coefficients with appropriate weights. The existing research shows that if two bipolar transistors with different parallel numbers work under the same current density, the difference value of the base-emitter voltages of the two bipolar transistors is proportional to the absolute temperature, namely positive temperature coefficient voltage. At a certain temperature, the base-emitter voltage of the bipolar collector transistor is basically in negative correlation with the absolute temperature.
As in fig. 1, the output reference voltage Vref is the sum of the base-emitter voltage of Q1 and the voltage across resistor R3. Wherein the base-emitter voltage of Q1 is inversely related to absolute temperature at a certain temperature; the difference between the base-emitter voltage of Q1 and the base-emitter voltage of Q2 produces a current across resistor R2 that is proportional to absolute temperature, while the currents across resistors R0 and R1 are equal, so the voltage drop across resistor R3 is proportional to absolute temperature. Therefore, the sum of the base-emitter voltage of Q1 and the voltage across resistor R3 achieves a first order compensation for absolute temperature, resulting in a zero-coefficient output reference voltage Vref.
Next, the output voltage of the operational amplifier is divided by resistors R4 and R5, and the output reference voltage Vref is fed back to the bases of Q1 and Q2, so that the power supply rejection ratio of the output reference voltage can be increased by increasing the gain of the operational amplifier. Let the transconductances of Q1 and Q2 be gmThe gain of the operational amplifier is AOPThe power supply rejection ratio of the operational amplifier is AVCCThen, the power supply rejection ratio of the output reference voltage Vref is:
wherein the content of the first and second substances,
RK2＝R1·gm·R2
therefore, when the bandgap reference circuit completes the first-order compensation, the resistance values of all the resistors R1-R5 and the transconductance gm of Q1 and Q2 are determined, and the power supply rejection ratio of the output reference voltage Vref can be improved by increasing the gain AOP of the operational amplifier.
Claims (7)
1. A band-gap reference circuit for improving power supply rejection ratio by using a feedback loop is characterized by specifically comprising: the output end of the operational amplifier is connected in series with a resistor R4 and a resistor R5 between the output end of the operational amplifier and the ground, the base electrode of a transistor Q1 is connected with the middle node of the resistor R4 and the resistor R5 which are connected in series, the middle node is an output reference voltage Vref node, the collector electrode of a transistor Q1 is respectively connected with the second end of a resistor R1 and the reverse input end of the operational amplifier, the emitter electrode of a transistor Q1 is grounded after being connected in series with the resistor R3, the base electrode of a transistor Q2 is connected with the output reference voltage Vref node, the collector electrode of a transistor Q2 is respectively connected with the second end of a resistor R0 and the same-direction input end of the operational amplifier, the emitter electrode of the transistor Q2 is grounded after being connected in series with the resistor R2 and the resistor R3 in sequence, the first end of the resistor R0 is connected with VDD, and the first end of the resistor R1 is connected with VDD.
2. The bandgap reference circuit with feedback loop for improving power supply rejection ratio as claimed in claim 1, wherein said transistor Q1 is NPN bipolar transistor.
3. The bandgap reference circuit with feedback loop for improving power supply rejection ratio as claimed in claim 1, wherein said transistor Q2 is NPN bipolar transistor.
4. The bandgap reference circuit with feedback loop for improving power supply rejection ratio as claimed in claim 1, wherein the resistance of the resistor R1 is equal to the resistance of the resistor R2.
5. The bandgap reference circuit with feedback loop for improving power supply rejection ratio as claimed in claim 1, wherein changing the size or parallel number of NPN bipolar transistor Q2 and the ratio of R3 to R2 can be used to improve the temperature coefficient and accuracy of the reference voltage.
6. A bandgap reference circuit with improved power supply rejection ratio using a feedback loop as claimed in claim 1, wherein the gain of the operational amplifier is increased for improving the power supply rejection ratio of the output reference voltage.
7. The bandgap reference circuit with feedback loop for improving power supply rejection ratio as claimed in claim 1, wherein said amplifier circuit is implemented by BiCMOS process.
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| CN202110563674.2A CN113342117A (en) | 2021-05-24 | 2021-05-24 | Band-gap reference circuit for improving power supply rejection ratio by using feedback loop |
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| CN202110563674.2A CN113342117A (en) | 2021-05-24 | 2021-05-24 | Band-gap reference circuit for improving power supply rejection ratio by using feedback loop |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113885642A (en) * | 2021-10-27 | 2022-01-04 | 四川宽鑫科技发展有限公司 | Band gap reference source with low temperature drift coefficient |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020049761A (en) * | 2000-12-20 | 2002-06-26 | 박종섭 | A CMOS bandgap reference voltage generator |
| CN104345765A (en) * | 2013-08-05 | 2015-02-11 | 日月光半导体制造股份有限公司 | Band gap reference voltage generation circuit and electronic system using same |
| CN105676928A (en) * | 2014-11-18 | 2016-06-15 | 华润矽威科技（上海）有限公司 | Band gap reference circuit |
| CN107121997A (en) * | 2017-05-08 | 2017-09-01 | 电子科技大学 | A kind of high-precision band-gap reference source compensated with self-adaption high-order |
-
2021
- 2021-05-24 CN CN202110563674.2A patent/CN113342117A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020049761A (en) * | 2000-12-20 | 2002-06-26 | 박종섭 | A CMOS bandgap reference voltage generator |
| CN104345765A (en) * | 2013-08-05 | 2015-02-11 | 日月光半导体制造股份有限公司 | Band gap reference voltage generation circuit and electronic system using same |
| CN105676928A (en) * | 2014-11-18 | 2016-06-15 | 华润矽威科技（上海）有限公司 | Band gap reference circuit |
| CN107121997A (en) * | 2017-05-08 | 2017-09-01 | 电子科技大学 | A kind of high-precision band-gap reference source compensated with self-adaption high-order |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113885642A (en) * | 2021-10-27 | 2022-01-04 | 四川宽鑫科技发展有限公司 | Band gap reference source with low temperature drift coefficient |
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