CN106656066A - Amplifying circuit of feedback signal of switch power source - Google Patents
Amplifying circuit of feedback signal of switch power source Download PDFInfo
- Publication number
- CN106656066A CN106656066A CN201611235718.4A CN201611235718A CN106656066A CN 106656066 A CN106656066 A CN 106656066A CN 201611235718 A CN201611235718 A CN 201611235718A CN 106656066 A CN106656066 A CN 106656066A
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- China
- Prior art keywords
- feedback signal
- input
- resistor
- circuit
- amplifier
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
Abstract
The invention discloses an amplifying circuit of a feedback signal of a switch power source. The amplifying circuit comprises an input circuit and an amplifier circuit; the input circuit comprises a first input end, a second input end, a first output end, a first capacitor, a second capacitor, a first transistor and a first resistor, wherein the first input end is used for accessing to the feedback signal of the switch power source; the first resistor is connected with the first capacitor in parallel; one end of the first resistor is connected with the first input end; the other end of the first resistor is connected with the drain electrode of the first transistor; the grid electrode of the first transistor is accessed to the second input end; one end of the second capacitor is grounded; and the other end of the second capacitor and the source electrode of the first transistor are connected to the first output end. By use of a zero sampling mode, the amplifying circuit of the feedback signal of the switch power source disclosed by the invention improves the dynamic response speed of a switch power source system and lowers the output ripple, thereby avoiding the stability problem of the whole system.
Description
Technical field
The present invention relates to technical field of integrated circuits, more particularly to a kind of amplifying circuit of the feedback signal of Switching Power Supply.
Background technology
It is well known that in switch power supply system, control circuit needs to carry out detection amplification to the feedback signal of system output,
Further according to the error signal regulating system output produced after amplification, so as to form stable closed-loop control.In switch power supply system
A switch periods in, the feedback signal of Switching Power Supply can be subdivided into as shown in Figure 1 five phase place interval, respectively
P1, p2, p3, p4 and p5, feedback signal is in stable low level p1 phase places are interval, in p2 phase places interval rapid increase,
P3 phase places are interval to be in unstable high level, interval in stable high level in p4 phase places, can now reflect that system is defeated
Go out voltage, be useful signal, in p5 phase places unstable low level is in.Magnitude of voltage energy only in wherein p4 phase places interval
Effectively reflection system output, needs amplifying circuit to retain the interval signal of this phase place as useful signal, to other
The interval signal of phase place is filtered as noise.
It is generally interval in effective phase place to feedback signal for the amplifying circuit of the feedback signal of traditional Switching Power Supply
Amplified with scaling circuit again after interior sampling and obtain error signal, in order that the speed of amplifying circuit meets requiring, often adopted
The sampled voltage for using non return to zero sample mode, i.e. each cycle persistently remains to the sampling instant of next cycle.Specifically,
First switch periods changes original state of the sampling capacitance in second switch periods in S1 position samplings, causes second
In S2 position samplings, sampled value error changes individual switch periods, while changing sampling capacitance again in the 3rd switch
The original state in cycle, causes the 3rd switch periods in S3 position samplings, and sampling error changes again.This mode will be controlled
Loop design processed is into idling slow speed system, although avoid the demand of circuit speed, but the dynamic that can reduce switch power supply system is rung
Answer speed；Simultaneously this mode can be such that sampling error constantly accumulates, and increase output ripple, and extreme case becomes can the stability of a system
Difference, and the effect of error accumulation can make system response time slower.
The content of the invention
The technical problem to be solved in the present invention is to overcome the amplification electricity of the feedback signal of prior art breaker in middle power supply
Road causes the defect that the dynamic responding speed of switch power supply system is slow, output ripple is more and system is unstable, there is provided a kind of
The dynamic responding speed that switch power supply system can be improved, the feedback for reducing output ripple and improving the Switching Power Supply of stability
The amplifying circuit of signal.
The present invention is to solve above-mentioned technical problem by following technical proposals：
A kind of amplifying circuit of the feedback signal of Switching Power Supply, its feature is, including input circuit and amplifier circuit；
The input circuit includes first input end, the second input, the first output end, the first electric capacity, the second electric capacity, the first transistor
And first resistor；The first input end is used to accessing the feedback signal of the Switching Power Supply, the first resistor and described the
One electric capacity is in parallel, and one end of the first resistor is connected with the first input end, the other end of the first resistor with it is described
The drain electrode of the first transistor is connected, grid access second input of the first transistor, and the one of second electric capacity
End ground connection, the other end and the source electrode of the first transistor of second electric capacity are connected to first output end；When described anti-
When feedback signal is in stable low level, second input switches to high level, when the feedback signal is in stable
During high level, second input switches to low level；The input phase of first output end and the amplifier circuit
Even, the amplifier circuit is used for output error signal.
In this programme, using the sample mode of zero, the level switching for controlling the second input by control signal is realized
Control to conducting and the disconnection of the first transistor.When feedback signal is in stable low level in p1 phase places interval, first
Transistor be in control signal the signal of the second input control under be switched to conducting state, the second electric capacity is used as sampling electricity
Hold, the electric charge of its storage is discharged by first resistor, realize that sampling capacitance resets.When feedback signal is interval quick in p2 phase places
During rising, the first electric capacity provides AC charging path for the second electric capacity, the first output end can be caused quickly to bring up to final
Near sampled voltage.When feedback signal is in stable high level in p4 phase places interval, the first transistor is in control signal
Off-state is switched under control, makes the second electric capacity that the sampling of this switch periods is completed in S2 positions.When feedback signal is in p5
When phase place is in unstable low level, the first transistor maintains under control of the control signal off-state, this time error letter
Number will not by feedback signal fluctuation be affected.
In this way, the amplifying circuit of the feedback signal of Switching Power Supply can be complete within each switch periods time
Reset into sampling capacitance, a series of processes such as sampled voltage is quickly set up, error signal is stably exported, it is ensured that each switch periods
Sampling be all independent, will not be affected by the sample information in front switch cycle, so as to avoid sampling error not
Disconnected accumulation, the dynamic responding speed for improving switch power supply system is slow, the problem that output ripple is more and system is unstable.
It is preferred that the input circuit also includes second resistance, one end of the second resistance and the first resistor
The other end is connected, the other end ground connection of the second resistance.
In this programme, first resistor and second resistance carry out voltage division processing to feedback signal, produce the feedback letter after partial pressure
Number, the feedback signal after the partial pressure is used for the voltage requirements of the input of adapter amplifier circuit.
It is preferred that the amplifier circuit includes amplifier and feedback network, first output end and the amplifier
Reverse input end be connected；The feedback network includes the 3rd electric capacity and the 4th resistance, the 3rd electric capacity and described 4th electric
Resistance is parallel to the reverse input end of the amplifier and the output end of the amplifier.
In this programme, when feedback signal is in unstable high level in p3 phase places interval, feedback signal includes one
High frequency noise content, the 3rd electric capacity is divided to play a part of LPF, make error signal high-frequency noises constituent reduction, prevent from touching
Send out subsequent conditioning circuit misoperation.
It is preferred that the amplifier circuit also includes 3rd resistor, the 3rd resistor is series at first output end
With the inverting input of the amplifier.
In this programme, amplifier amplifies to feedback signal, and the ratio of amplification is adjusted by the ratio of 3rd resistor and the 4th resistance
Section, using analog filter accurate amplifier in a switch periods is realized.
It is preferred that the first transistor is NMOS (N-type Metal-oxide-semicondutor) pipes.
The present invention positive effect be：The amplifying circuit of the feedback signal of the Switching Power Supply that the present invention is provided passes through
The sample mode of zero, can complete that sampling capacitance resets, sampled voltage is quickly set up, instead within each switch periods time
Feedback signal noise filtering, error signal such as stably export at a series of processes, improve the dynamic responding speed of switch power supply system,
Reduce output ripple, it is to avoid whole system stability problem occur.
Description of the drawings
Fig. 1 is the schematic diagram of the feedback signal of Switching Power Supply.
Fig. 2 is the circuit diagram of the amplifying circuit of the feedback signal of the Switching Power Supply of a preferred embodiment of the present invention.
Specific embodiment
The present invention is further illustrated below by the mode of embodiment, but does not therefore limit the present invention to described reality
Among applying a scope.
As shown in Fig. 2 a kind of amplifying circuit of the feedback signal of Switching Power Supply, including input circuit 101 and amplifier electricity
Road 102.Wherein input circuit 101 includes first input end, the second input, the first output end, the first electric capacity C1, the second electric capacity
C2, the first transistor M1, first resistor R1 and second resistance R2, wherein the first transistor M1 are NMOS tube.
First input end is used to access feedback signal VFB of Switching Power Supply, and the second input accesses an external control signal
Vsw, the first output end exports the second feedback signal Vf2 to amplifier circuit 102, and amplifier circuit 102 is used for according to input
Second feedback signal Vf2 output error signal Verr.
First resistor R1 and the first electric capacity C1 are in parallel, and one end of first resistor R1 is connected with first input end, first resistor
The other end of R1 is connected with the drain electrode of the first transistor M1, and the grid of the first transistor M1 accesses the second input, the second electric capacity
One end ground connection of C2, the other end of the second electric capacity C2 is connected to the first output end with the source electrode of the first transistor M1.Work as feedback signal
When VFB is in stable low level, the second input switches to high level under the control of external control signal Vsw, control the
One transistor M1 switches to conducting state；When feedback signal VFB is in stable high level, the second input is in external control
Low level, control the first transistor M1 is switched to switch to off state under the control of signal Vsw；One end of second resistance R2 with
The other end of first resistor R1 is connected, the other end ground connection of second resistance R2.
Amplifier circuit 102 includes 3rd resistor R3, amplifier AMP and feedback network 1021, and feedback network 1021 includes
3rd electric capacity C3 and the 4th resistance R4.First output end is connected with the reverse input end of amplifier AMP；3rd electric capacity C3 and the 4th
Resistance R4 is parallel to the output end of the reverse input end of amplifier AMP and amplifier AMP.3rd resistor R3 is series at the first output
End and the inverting input of amplifier AMP, the second feedback signal Vf2 produces sum voltages Vsum Jing after 3rd resistor R3.Summation
Voltage Vsum is exported to the reverse input end of amplifier AMP, and the homophase input of amplifier AMP terminates a reference voltage Vref, puts
The big output error signal Verr of device circuit 102.
The amplifying circuit of the feedback signal of the Switching Power Supply that the present embodiment is provided uses the sample mode of zero instead, works as feedback letter
Number VFB p1 phase places it is interval in stable low level when, the original state of the second electric capacity C2 is resetted, when feedback signal VFB
When p4 phase places interval is in stable high level, the second electric capacity C2 completes the sampling to feedback signal, it is ensured that each switch week
The sampling of phase is all independent, will not be affected by the sample information in front switch cycle.After changing in this way, second is electric
Hold original states of the C2 before S2 instance samples, the relatively low current potential at p1 is changed to by the higher current potential of S1, originally put
Big circuit improves the response speed of switch power supply system.
In the present embodiment, first resistor R1 and second resistance R2 produce the first feedback signal to feedback signal VFB partial pressure
Vf1.When feedback signal is in stable low level in p1 phase places interval, the first transistor M1 is external control signal Vsw's
Conducting state is switched under control, the second electric capacity C2 is used as sampling capacitance, the electric charge of its storage passes through first resistor R1 and second
Resistance R2 discharges, and realizes that sampling capacitance resets.When feedback signal is when in p2 phase places interval rapid increase, the first electric capacity C1 is the
Two electric capacity C2 provide AC charging path, and the second feedback signal Vf2 can be made quickly to bring up near final sampled voltage.
In the present embodiment, amplifier AMP amplifies to the second feedback signal Vf2, and the ratio of amplification is by 3rd resistor R3 and
The proportion adjustment of four resistance R4.When feedback signal VFB is in unstable high level in p3 phase places interval, the second feedback signal
Vf2 can also include a part of high frequency noise content, and the 3rd electric capacity C3 plays a part of LPF, make high in error signal Verr
Frequency noise contribution is reduced, and prevents triggering following circuit erroneous action.When feedback signal VFB in p4 phase places interval in stable height electricity
At ordinary times, the first transistor M1 is switched to off-state under the control of external control signal Vsw, makes the second electric capacity C2 in S2 positions
Complete the sampling of this switch periods.When feedback signal is in unstable low level in p5 phase places, the first transistor M1 exists
Off-state is maintained under the control of external control signal Vsw, now error signal Verr will not be subject to the fluctuation of feedback signal VFB
Affect.
In this way, the amplifying circuit of the feedback signal of Switching Power Supply can be complete within each switch periods time
Reset into sampling capacitance, a series of mistakes such as sampled voltage is quickly set up, feedback signal noise filtering, error signal are stably exported
Journey, improves the dynamic response of switch power supply system, it is to avoid the stability problem of whole system occur.
Although the specific embodiment of the present invention is the foregoing described, it will be appreciated by those of skill in the art that this is only
It is to illustrate, protection scope of the present invention is defined by the appended claims.Those skilled in the art without departing substantially from
On the premise of the principle and essence of the present invention, various changes or modifications can be made to these embodiments, but these changes and
Modification each falls within protection scope of the present invention.
Claims (5)
1. a kind of amplifying circuit of the feedback signal of Switching Power Supply, it is characterised in that including input circuit and amplifier circuit；
The input circuit includes first input end, the second input, the first output end, the first electric capacity, the second electric capacity, first brilliant
Body pipe and first resistor；
The first input end is used to access the feedback signal of the Switching Power Supply, and the first resistor and first electric capacity are simultaneously
Connection, one end of the first resistor is connected with the first input end, the other end of the first resistor and the first crystal
The drain electrode of pipe is connected, and the grid of the first transistor accesses second input, one end ground connection of second electric capacity, institute
The other end and the source electrode of the first transistor for stating the second electric capacity is connected to first output end；When the feedback signal is in
During stable low level, second input switches to high level, when the feedback signal is in stable high level, institute
State the second input and switch to low level；First output end is connected with the input of the amplifier circuit, the amplification
Device circuit is used for output error signal.
2. the amplifying circuit of the feedback signal of Switching Power Supply as claimed in claim 1, it is characterised in that the input circuit is also
Including second resistance, one end of the second resistance is connected with the other end of the first resistor, the second resistance it is another
End ground connection.
3. the amplifying circuit of the feedback signal of Switching Power Supply as claimed in claim 1, it is characterised in that the amplifier circuit
Including amplifier and feedback network, first output end is connected with the reverse input end of the amplifier；The feedback network
Including the 3rd electric capacity and the 4th resistance, the 3rd electric capacity and the 4th resistor coupled in parallel are in the reverse input end of the amplifier
With the output end of the amplifier.
4. the amplifying circuit of the feedback signal of Switching Power Supply as claimed in claim 3, it is characterised in that the amplifier circuit
Also include 3rd resistor, the 3rd resistor is series at the inverting input of first output end and the amplifier.
5. the amplifying circuit of the feedback signal of the Switching Power Supply as described in any one of Claims 1-4, it is characterised in that described
The first transistor is NMOS tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611235718.4A CN106656066B (en) | 2016-12-28 | 2016-12-28 | Feedback signal amplifying circuit of switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611235718.4A CN106656066B (en) | 2016-12-28 | 2016-12-28 | Feedback signal amplifying circuit of switching power supply |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106656066A true CN106656066A (en) | 2017-05-10 |
| CN106656066B CN106656066B (en) | 2020-02-07 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201611235718.4A Active CN106656066B (en) | 2016-12-28 | 2016-12-28 | Feedback signal amplifying circuit of switching power supply |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102347758A (en) * | 2010-08-05 | 2012-02-08 | 中国人民解放军国防科学技术大学 | Slope compensation and summing circuit with configurable slope |
| CN203674971U (en) * | 2013-12-12 | 2014-06-25 | 深圳市金威源科技股份有限公司 | Switch power feedback circuit |
| US20150249457A1 (en) * | 2014-02-28 | 2015-09-03 | Rohm Co., Ltd. | Double-integration type a/d converter |
-
2016
- 2016-12-28 CN CN201611235718.4A patent/CN106656066B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102347758A (en) * | 2010-08-05 | 2012-02-08 | 中国人民解放军国防科学技术大学 | Slope compensation and summing circuit with configurable slope |
| CN203674971U (en) * | 2013-12-12 | 2014-06-25 | 深圳市金威源科技股份有限公司 | Switch power feedback circuit |
| US20150249457A1 (en) * | 2014-02-28 | 2015-09-03 | Rohm Co., Ltd. | Double-integration type a/d converter |
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| Publication number | Publication date |
|---|---|
| CN106656066B (en) | 2020-02-07 |
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