CN106208998A - A kind of small-signal ac amplifier circuit - Google Patents
A kind of small-signal ac amplifier circuit Download PDFInfo
- Publication number
- CN106208998A CN106208998A CN201610589655.6A CN201610589655A CN106208998A CN 106208998 A CN106208998 A CN 106208998A CN 201610589655 A CN201610589655 A CN 201610589655A CN 106208998 A CN106208998 A CN 106208998A
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- Prior art keywords
- resistance
- signal
- unit
- circuit
- outfan
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
- H03G3/3026—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being discontinuously variable, e.g. controlled by switching
Abstract
The present invention is applicable to electronic applications, it is provided that a kind of small-signal ac amplifier circuit, and this circuit includes: amplifying unit, for being amplified input small-signal, generates and amplifies signal；Detector unit, is used for detecting amplification signal, and generates corresponding switch-over control signal according to amplifying the strong and weak of signal, and the input of detector unit is connected with the outfan of amplifying unit；Switch unit, for the gain according to switch-over control signal regulation amplifying unit, the input of switch unit is connected with the outfan of detector unit, and the outfan of switch unit is connected with the feedback end of amplifying unit.The present invention is by increasing different gains circuit, when the output of present segment signal is more weak, amplify through plus and blowup circuit, when the output of present segment signal is stronger, amplify through low gain amplifying circuit, so that its output is maintained at certain limit value, for the fluctuation of small-signal, being difficult to lose the signal of upper and lower limit, output accuracy is high.
Description
Technical field
The invention belongs to electronic applications, particularly relate to a kind of small-signal ac amplifier circuit.
Background technology
Operational amplification circuit generally utilizes operational amplifier to be amplified input signal, wherein as a kind of common circuit
The structure of operational amplifier can be divided into: reversal amplifier, non-inverted amplifier, adder, subtractor, integrating circuit, differential
Circuit, difference channel etc..
But, current small signal amplification circuit all uses fixing amplifying circuit, such as Fig. 1, including: fortune amplifier OP1
With resistance R1, resistance R2, one end of resistance R1 is signal input part, and one end and the computing of the other end of resistance R1 and resistance R2 are put
The reverse input end of big device OP1 connects, the positive input ground connection of operational amplifier OP1, the outfan of operational amplifier OP1 with
The other end of resistance R2 connects, and signal is amplified in output.
In said structure, when the output of present segment signal is more weak, after this amplifying circuit amplifies, do not reach rear class sampling
Requirement, therefore lose this signal；When the output of present segment signal is stronger, after this amplifying circuit amplifies, want beyond rear class sampling
Asking, same this signal of loss, therefore, existing small signal amplification circuit has certain limitation for signal fluctuation, be easily lost,
The signal of lower limit, or output distortion etc..
Summary of the invention
The purpose of the embodiment of the present invention is to provide a kind of small-signal ac amplifier circuit, it is intended to solves existing small-signal and puts
The problem that big circuit causes signal to be easily lost by fixing amplification, output accuracy is low.
The embodiment of the present invention is achieved in that a kind of small-signal ac amplifier circuit, and described circuit includes:
Amplifying unit, for being amplified input small-signal, generates and amplifies signal；
Detector unit, is used for detecting described amplification signal, and generates corresponding switching according to the strong and weak of described amplification signal
Control signal, the input of described detector unit is connected with the outfan of described amplifying unit；
Switch unit, for regulating the gain of described amplifying unit, described switch unit according to described switch-over control signal
Input be connected with the outfan of described detector unit, the feedback end of the outfan of described switch unit and described amplifying unit
Connect.
The embodiment of the present invention is by increasing different gains circuit, when the output of present segment signal is more weak, through plus and blowup
Circuit amplifies, and when the output of present segment signal is stronger, amplifies through low gain amplifying circuit, so that its output is maintained at certain model
Enclosing value, for the fluctuation of small-signal, be difficult to lose the signal of upper and lower limit, output accuracy is high.
Accompanying drawing explanation
Fig. 1 is the circuit structure diagram of existing small signal amplification circuit；
The structure chart of the small-signal ac amplifier circuit that Fig. 2 provides for the embodiment of the present invention；
One exemplary circuit structure chart of the small-signal ac amplifier circuit that Fig. 3 provides for the embodiment of the present invention；
Another exemplary circuit structure chart of the small-signal ac amplifier circuit that Fig. 4 provides for the embodiment of the present invention.
Detailed description of the invention
In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, right
The present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, and
It is not used in the restriction present invention.If additionally, technical characteristic involved in each embodiment of invention described below
The conflict of not constituting each other just can be mutually combined.
The embodiment of the present invention is by increasing different gains circuit, when the output of present segment signal is more weak, through plus and blowup
Circuit amplifies, and when the output of present segment signal is stronger, amplifies through low gain amplifying circuit, so that its output is maintained at certain model
Enclosing value, for the fluctuation of small-signal, be difficult to lose the signal of upper and lower limit, output accuracy is high.
Fig. 2 shows the structure of the small-signal ac amplifier circuit that the embodiment of the present invention provides, and for convenience of description, only shows
Go out part related to the present invention.
As one embodiment of the invention, this small-signal ac amplifier circuit includes:
Amplifying unit 11, for being amplified input small-signal, generates and amplifies signal；
Detector unit 12, is used for detecting described amplification signal, and generates corresponding cutting according to the strong and weak of described amplification signal
Changing control signal, the input of detector unit 12 is connected with the outfan of amplifying unit 11；
Switch unit 13, for the gain according to switch-over control signal regulation amplifying unit, the input of switch unit 13
Being connected with the outfan of detector unit 12, the outfan of switch unit 13 is connected with the feedback end of amplifying unit 11.
In embodiments of the present invention, the small-signal Vin of input generates after amplifying and amplifies signal Vout, detector unit 12
The size of signal Vout is amplified in detection, and by the power of threshold decision amplification signal Vout, if amplifying signal Vout more than threshold
Value, then corresponding generation reduces the switch-over control signal of gain, if amplification signal Vout is less than threshold value, then corresponding generation increases gain
Switch-over control signal, thus drive switch unit 13 to switch the gain that varies in size, control amplifying unit 11 by gain-adjusted
To suitable amplification gear, to keep output stable.
Fig. 3 shows an exemplary circuit structure of the small-signal ac amplifier circuit that the embodiment of the present invention provides, in order to just
In explanation, illustrate only part related to the present invention.
As one embodiment of the invention, this amplifying unit 11 includes:
Resistance R3, resistance R4, resistance R5 and four-operational amplifier U4-A；
One end of resistance R3 is the input of amplifying unit 11, the other end of resistance R3 and four-operational amplifier U4-A's
Reverse input end connects, and the reverse input end of four-operational amplifier U4-A even with one end of resistance R4 and resistance R5 also simultaneously
Connecing, the other end of resistance R4 and resistance R5 is respectively the first feedback end of amplifying unit 11 and the second feedback end and switch unit 13
Two outfans connect, the positive input ground connection of four-operational amplifier U4-A, the outfan of four-operational amplifier U4-A
Outfan for amplifying unit 11.
Detector unit 12 includes:
Resistance R6, resistance R7, resistance R8, the first switching tube Q1 and the 5th microprocessor U5；
One end of resistance R6 is the input of detector unit 12, the other end of resistance R6 and the detection of the 5th microprocessor U5
End AD0 connects, and the power end VDD of the 5th microprocessor U5 connects+5V supply voltage, the earth terminal GND of the 5th microprocessor U5
Ground connection, the outfan I/O of the 5th microprocessor U5 connects one end of resistance R7, the other end of resistance R7 simultaneously with the one of resistance R8
The control end of end and the first switching tube Q1 connects, and the outfan that input is detector unit 12 of the first switching tube Q1, first opens
Close the output head grounding of pipe Q1, the other end ground connection of resistance R8.
Preferably, the first switching tube Q1 is NPN type triode, and the base stage of NPN type triode is the control of the first switching tube Q1
End processed, the input of the current collection of NPN type triode the extremely first switching tube Q1, the transmitting of NPN type triode extremely first switchs
The outfan of pipe Q1.
Preferably, the 5th microprocessor U5 is single-chip microcomputer.
Switch unit 13 includes:
Relay K 1 and diode D1；
The anode of described diode D1 is that the input of described switch unit 13 is connected with 8 feet of described relay K 1, institute
1 foot of the negative electrode and described relay K 1 of stating diode D1 is simultaneously connected with+5V supply voltage, 2 feet of described relay K 1 and 4 feet
Two outfans being respectively described switch unit 13 are connected with the other end of resistance R5, resistance R4, and 3 feet of described relay K 1 are even
Connect the outfan of amplifying unit 11.
The model of relay K 1 can be preferably G6K-2F-Y, and 1 foot of relay K 1 and 8 feet are for controlling end, and controlling end is
2 feet and 3 feet Guan Bi, 7 feet and 6 feet Guan Bi during low level, control 4 feet and 3 feet Guan Bi, 5 feet and 6 feet Guan Bi when end is high level.
In embodiments of the present invention, input small-signal Vin inputs through resistance R3, via four-operational amplifier U4-A and electricity
The amplifying return circuit of resistance R4 composition amplifies, or amplifies via the amplifying return circuit of four-operational amplifier U4-A and resistance R5 composition,
Generate and amplify signal；
Here the resistance of resistance R5 could be arranged to 10 times of resistance R4, relay K 1 by switch switching by difference resistance
Resistance R4 or resistance R5 as the feedback resistance of amplifier, thus realize the regulation to amplifier gain, certainly, resistance R4 and resistance
The resistance ratio of R5 is not limited to 10 times, can arrange according to reality application.
Exporting through amplification signal Vout mono-tunnel of amplifying unit 11 amplifier, single-chip microcomputer U5's received through resistance R6 in another road
Test side AD0, single-chip microcomputer U5 compare amplifying signal Vout with the threshold value preset, and output increases or reduces the switching of gain
Control signal gives, by switching tube Q1, the selection that switch unit 13 controls different gains.
In embodiments of the present invention, by increasing different gains circuit, when the output of present segment signal is more weak, through high-gain
After amplifying circuit amplifies so that it is reach rear class sampling request, this signal can be collected；When the output of present segment signal is stronger, warp
After too low gain amplifying circuit amplifies so that it is reach rear class sampling request, so that its output is maintained at certain limit value.
Such as, in existing typical practical applications, gain amplifier being fixed on 100dB or 120dB, leading portion is sampled
When signal is millivolt, after amplifying circuit amplifies 1000 times, if rear class sampling request millivolt level, therefore front signal output millivolt
(mV) signal is beyond sample range: mV*1000=1V.
And after using the technical scheme that the embodiment of the present invention provides, no matter present segment sampled signal receives volt (nV) or millivolt
(mV), output all can be made to be maintained in the claimed range of rear class sampling, when sampled signal is at nV, switching is amplified to 1000 times
After, export mV level；During present segment sampled signal output mV, switching is amplified to 1 times, exports also mV level: nV*1000=mV, mV*1
=mV, after gain switching amplifying circuit amplifies, all can reach rear class sampling request.
The embodiment of the present invention, for the fluctuation of small-signal, is easily lost the signal of upper and lower limit, by increasing this circuit, and can
To automatically switch to corresponding gear when signal fluctuation, thus accurately amplifying signal, small-signal precise and stable, good reliability is put
Big circuit, and this is simple and reliable for structure, amplifies accurate stable, there is not the problems such as frequency interferences.
Fig. 4 shows an exemplary circuit structure of the small-signal ac amplifier circuit that the embodiment of the present invention provides, in order to just
In explanation, illustrate only part related to the present invention.
As one embodiment of the invention, this amplifying unit 11 includes:
Resistance R11, resistance R13, resistance R14, resistance R15, resistance R16 and the first operational amplifier U1-A；
One end of resistance R11 is the input of amplifying unit 11, the other end of resistance R11 and the first operational amplifier U1-A
Reverse input end connect, the positive input ground connection of the first operational amplifier U1-A, the output of the first operational amplifier U1-A
The outfan that end is amplifying unit 11 is connected with resistance R13, resistance R14, resistance R15, one end of resistance R16 simultaneously, resistance
R13, resistance R14, resistance R15, the other end of resistance R16 are respectively four feedback ends of amplifying unit 11 with switch unit 13 even
Connect.
Detector unit 12 includes:
Resistance R12 and the second microprocessor U2；
One end of resistance R12 is the input of detector unit 12, the other end of resistance R12 and the inspection of the second microprocessor U2
Surveying end AD0 to connect, the power end VDD of the second microprocessor U2 connects+5V supply voltage, the earth terminal of the second microprocessor U2
GND ground connection, first, second outfan that the two outfan I/O of the second microprocessor U2 are respectively detector unit 12 is single with switching
Unit 13 connects.
Preferably, the second microprocessor U2 is single-chip microcomputer.
Switch unit 13 can use multiplexer switch ADG659 to realize, wherein No. four outfans of multiplexer switch
Four outfans (X0, X1, X2, X3) being respectively switch unit 13 are connected with four feedback ends of amplifying unit 11, and multichannel is multiple
It is connected with the reverse input end of the first operational amplifier U1-A in amplifying unit 11 with the selection end (A) of switch.
In embodiments of the present invention, input small-signal Vin inputs through resistance R11, divides via the first operational amplifier U1-A
Other and resistance R13, resistance R14, resistance R15, resistance R16 form the amplifying return circuit of different gains, generate and amplify signal；
Here resistance R14, resistance R15, the resistance of resistance R16 can be respectively set to 10 times of resistance R13,100 times,
1000 times, by multiplexer switch, the feedback resistance of different resistances is switched into amplifying return circuit, thus realizes different gains
Amplifying and select, certainly, resistance R13, resistance R14, resistance R15, the resistance ratio of resistance R16 are not limited to 10,100,1000
Times, can arrange according to reality application.
Exporting through amplification signal Vout mono-tunnel of amplifying unit 11 amplifier, single-chip microcomputer U2 is received through resistance R12 in another road
Test side AD0, single-chip microcomputer U2 compare amplifying signal Vout with the threshold value preset, output increases or reduction the cutting of gain
Change control signal and control the selection of different gains to switch unit 13.
In embodiments of the present invention, by increasing different gains circuit, when the output of present segment signal is more weak, through high-gain
After amplifying circuit amplifies so that it is reach rear class sampling request, this signal can be collected；When the output of present segment signal is stronger, warp
After too low gain amplifying circuit amplifies so that it is reach rear class sampling request, so that its output is maintained at certain limit value.
The embodiment of the present invention, for the fluctuation of small-signal, is easily lost the signal of upper and lower limit, by increasing this circuit, and can
To automatically switch to corresponding gear when signal fluctuation, thus accurately amplifying signal, small-signal precise and stable, good reliability is put
Big circuit, and the advantage of this structure be circuit lifetime length, safe and reliable, there is no that mechanical wear, switching speed are fast, volume is little,
It is readily produced.
These are only presently preferred embodiments of the present invention, not in order to limit the present invention, all spirit in the present invention and
Any amendment, equivalent and the improvement etc. made within principle, should be included within the scope of the present invention.
Claims (8)
1. a small-signal ac amplifier circuit, it is characterised in that described circuit includes:
Amplifying unit, for being amplified input small-signal, generates and amplifies signal；
Detector unit, is used for detecting described amplification signal, and generates corresponding switching control according to the strong and weak of described amplification signal
Signal, the input of described detector unit is connected with the outfan of described amplifying unit；
Switch unit, for regulating the gain of described amplifying unit, described switch unit defeated according to described switch-over control signal
Entering end to be connected with the outfan of described detector unit, the outfan of described switch unit connects with the feedback end of described amplifying unit
Connect.
2. circuit as claimed in claim 1, it is characterised in that described amplifying unit includes:
Resistance R3, resistance R4, resistance R5 and four-operational amplifier；
The input that one end is described amplifying unit of described resistance R3, the other end of described resistance R3 is put with described 4th computing
The reverse input end of big device connects, the reverse input end of described four-operational amplifier also simultaneously with described resistance R4 and described electricity
One end of resistance R5 connects, and the other end of described resistance R4 and described resistance R5 is respectively first feedback end and second of amplifying unit
Feedback end, the positive input ground connection of described four-operational amplifier, the outfan of described four-operational amplifier be described in put
The outfan of big unit.
3. circuit as claimed in claim 2, it is characterised in that described switch unit includes:
Relay and diode D1；
The input that anode is described switch unit of described diode D1 is connected with 8 feet of described relay, described diode
The negative electrode of D1 is simultaneously connected with supply voltage with 1 foot of described relay, and 2 feet and 4 feet of described relay are respectively described switching
Two outfans of unit, 3 feet of described relay connect the outfan of described amplifying unit.
4. circuit as claimed in claim 1, it is characterised in that described detector unit includes:
Resistance R6, resistance R7, resistance R8, the first switching tube and the 5th microprocessor；
The input that one end is described detector unit of described resistance R6, the other end of described resistance R6 and described 5th micro-process
The test side of device connects, and the outfan of described 5th microprocessor connects one end of described resistance R7, another of described resistance R7
End is connected with the control end of one end of described resistance R8 and described first switching tube simultaneously, and the input of described first switching tube is
The outfan of described detector unit, the output head grounding of described first switching tube, the other end ground connection of described resistance R8.
5. circuit as claimed in claim 4, it is characterised in that described first switching tube is NPN type triode, described NPN type
The base stage of audion is the control end of described first switching tube, the most described first switching tube of current collection of described NPN type triode
Input, the outfan of the most described first switching tube of transmitting of described NPN type triode.
6. circuit as claimed in claim 1, it is characterised in that described amplifying unit includes:
Resistance R11, resistance R13, resistance R14, resistance R15, resistance R16 and the first operational amplifier；
The input that one end is described amplifying unit of described resistance R11, the other end of described resistance R11 and described first computing
The reverse input end of amplifier connects, the positive input ground connection of described first operational amplifier, described first operational amplifier
The outfan that outfan is described amplifying unit simultaneously with described resistance R13, described resistance R14, described resistance R15, described
One end of resistance R16 connects, described resistance R13, described resistance R14, described resistance R15, the other end difference of described resistance R16
Four feedback ends for described amplifying unit.
7. circuit as claimed in claim 6, it is characterised in that described switch unit is multiplexer switch, wherein said many
No. four outfans of road multiplex switch are respectively four outfans of described switch unit, the selection end of described multiplexer switch
It is connected with the reverse input end of described first operational amplifier.
8. circuit as claimed in claim 1, it is characterised in that described detector unit includes:
Resistance R12 and the second microprocessor；
The input that one end is described detector unit of described resistance R12, the other end of described resistance R12 and described second micro-place
The test side of reason device connects, and two outfans of described second microprocessor are respectively first, second output of described detector unit
End.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610589655.6A CN106208998A (en) | 2016-07-22 | 2016-07-22 | A kind of small-signal ac amplifier circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610589655.6A CN106208998A (en) | 2016-07-22 | 2016-07-22 | A kind of small-signal ac amplifier circuit |
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| Publication Number | Publication Date |
|---|---|
| CN106208998A true CN106208998A (en) | 2016-12-07 |
Family
ID=57494889
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610589655.6A Pending CN106208998A (en) | 2016-07-22 | 2016-07-22 | A kind of small-signal ac amplifier circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116295986A (en) * | 2023-05-24 | 2023-06-23 | 无锡卓海科技股份有限公司 | Optical signal processing device, method and stress detection system |
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| CN104166533A (en) * | 2014-08-08 | 2014-11-26 | 深圳市九洲电器有限公司 | Audio output method and system |
| CN205051657U (en) * | 2015-09-10 | 2016-02-24 | 湖南工业大学 | Automatic gain amplifier based on MSP430G2553 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001308663A (en) * | 2000-04-27 | 2001-11-02 | New Japan Radio Co Ltd | Variable gain amplifier circuit |
| US20040239421A1 (en) * | 2003-03-27 | 2004-12-02 | Realtek Semiconductor Corp. | Variable gain amplifier |
| CN1734933A (en) * | 2004-08-13 | 2006-02-15 | 深圳赛意法微电子有限公司 | Have adaptive climbing and the AGC (automatic gain control) system of die-away time |
| CN102624345A (en) * | 2012-04-09 | 2012-08-01 | 武汉科技大学 | Memristor-based automatic gain control circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116295986A (en) * | 2023-05-24 | 2023-06-23 | 无锡卓海科技股份有限公司 | Optical signal processing device, method and stress detection system |
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Application publication date: 20161207 |