CN103441742B - Gain control circuit - Google Patents
Gain control circuit Download PDFInfo
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- CN103441742B CN103441742B CN201310317887.2A CN201310317887A CN103441742B CN 103441742 B CN103441742 B CN 103441742B CN 201310317887 A CN201310317887 A CN 201310317887A CN 103441742 B CN103441742 B CN 103441742B
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Abstract
The present invention relates to electronic circuit, disclose a kind of gain control circuit.In the present invention, gain control circuit comprises preamplifying circuit, switch and integrator circuit.Preamplifying circuit is used for the prime signal receiving audio signal and exporting amplification；Prime signal packet prime containing positive signal and anti-phase prime signal；Preamplifying circuit comprises positive audio signal input end, anti-phase audio signal input end, positive prime signal output part and anti-phase prime signal output part；One end of switch is connected with positive prime signal output part, and the other end is connected with anti-phase prime signal output part；Integrator circuit is used for receiving the prime signal of output feedback signal and preamplifying circuit output, and is exported by described output feedback signal and prime signal shaping and filtering and after subtracting each other.The invention enables avoiding the input resistance in gain control circuit and feedback resistance segmentation, solve audio frequency power amplifier chip wiring difficult, it is to avoid adjust " clicker " sound during gain control circuit gain.
Description
Technical field
The present invention relates to electronic circuit, particularly to a kind of gain control circuit of audio frequency power amplifier chip.
Background technology
In audio power amplification system, gain is a key parameter index, is defined as the ratio of output signal and input signal.
Concordance between the precision of gain and sample is to weigh power discharging IC（Integrated circuit, Integrated Circuit）Quality is good
One of bad standard, gain control is one of whole audio power amplification system important component part.During design system, for essence
The gain of true ground control system, usually the ratio by the resistance of closed loop system to realize, i.e. A=RF/RIN.Wherein, A is system
Gain, RFIt is the feedback resistance of system, RINIt is the input resistance of signal.
Fig. 1 is the structural representation of a more universal gain control circuit for audio frequency power amplifier chip.Wherein, input electricity
Resistance RI, feedback resistance RFForm the preamplifying circuit of power amplifier chips, input resistance R with difference transport and placing deviceIComprise resistance RI1, electricity
Resistance RI2, resistance RI1, resistance RI2Resistance is equal, feedback resistance RFComprise resistance RF1, resistance RF2, resistance RF1, resistance RF2Resistance phase
Deng.Audio signal VIBy resistance RI、RFCircuit network obtains prime signal V after amplifyingO1, audio signal VIThe gain A amplifiedV
By resistance RI、RFRatio setting, AV=VO1/VI=RF/RI.Resistance R1, resistance R2, electric capacity C1, electric capacity C2With difference transport and placing device group
Become integrator circuit.Prime signal VO1With output feedback signal VF1Through integrator circuit shaping filter and complete to subtract each other.In work(
Put in application, because the amplitude of signal source is inconsistent, need gain on Regulate signal path to realize power amplifier output volume
Comfort level.
At this stage, gain-adjusted is that power discharging IC needs an integrated basic function, and general way is to be changed by segmentation
Become resistance RFWith resistance RINResistance completing, as shown in Figure 2.Wherein, resistance RFWith resistance RIIt is processed into multistage resistance
Series connection：Rn1、Rn2、Rn3、……、Rnn-1、Rnn、Rnn+1, the resistance of these resistance is the gain curve being needed according to system come reconnaissance
Set.Gain control tap net is chosen according to the condition that user sets1、net2、net3、……netn-1、netn.For example,
When choosing net2, signal gain is：
But, this technical scheme by resistor section, during physics realization, the cloth of the resistance of gain control circuit
Lineman makees will be extremely difficult, and wastes chip area.Because resistance segmentation in proportion, need input resistance RIAnd feedback resistance
RFIt is divided into multiple resistances.Because the physical size of the resistance of different value is also different, the series of gain control is more, and system needs
The resistance species of resistance is also more.
Meanwhile, in power amplifier application aspect, voltage jump is exaggerated in power take-off, and user can hear and be unwilling to hear
" clicker " sound.Due to being by resistance segmentation in proportion, there is larger difference in the resistance between resistance, and even conventional 64 grades increase
It is also such that benefit controls.During gain changes, the change of voltage signal is sufficiently oily, there is the change of moment.
Content of the invention
It is an object of the invention to provide a kind of gain control circuit is so that avoid dividing input resistance and feedback resistance
Section, solve audio frequency power amplifier chip wiring difficult, it is to avoid adjusts " clicker " sound during gain control circuit gain.
For solving above-mentioned technical problem, the invention provides a kind of gain control circuit, comprise：Preamplifying circuit, open
Close and integrator circuit；
Described preamplifying circuit is used for the prime signal receiving audio signal and exporting amplification；Described audio signal comprises
Positive audio signal and anti-phase audio signal；Described prime signal packet prime containing positive signal and anti-phase prime signal；Before described
Level amplifying circuit comprise two inputs and two outfans, described two inputs be respectively positive audio signal input end,
Anti-phase audio signal input end, described two outfans are respectively positive prime signal output part, anti-phase prime signal output part；
One end of described switch is connected with described positive prime signal output part, and the other end is defeated with described anti-phase prime signal
Go out end to connect；
Described integrator circuit is used for receiving the prime signal of output feedback signal and the output of described preamplifying circuit, and
Exported by described output feedback signal and prime signal shaping and filtering and after subtracting each other；Wherein, described output feedback signal bag
Output feedback signal containing positive and anti-phase output feedback signal；
Described integrator circuit comprise positive output feedback signal input, anti-phase output feedback signal input terminal, first
Outfan and the second outfan；Described positive output feedback signal input is connected with described positive prime signal output part, institute
State anti-phase output feedback signal input terminal to connect with described anti-phase prime signal output part, described first outfan and second exports
The signal output held described shaping filter and subtract each other.
Embodiment of the present invention in terms of existing technologies, is realized the amplification of audio signal by preamplifying circuit, by
Output feedback signal and prime, to control prime to amplify the decay of signal, are amplified signal by integrator by the on or off of switch
Carry out shaping filter and exported after subtracting each other.Control the gain of gain control circuit by controlling switch ON time, should
Do not need input resistance and feedback resistance segmentation in proportion in gain control circuit, solve audio frequency power amplifier chip wiring and be stranded
Difficult, it is to avoid to adjust " clicker " sound during gain control circuit gain.
In addition, switch is by control circuit of duty ratio control.Adjust described gain control electricity by adjusting duty cycle of switching
The gain on road, can realize step-less adjustment gain, the more suitability in certain limit.
In addition, this gain control circuit comprises 3rd resistor R3, the 4th resistance R4；Described resistance R3It is connected on the one of switch
Between end and described positive prime signal output part；Described resistance R4It is connected on the other end of switch and described anti-phase prime signal
Between outfan.Described resistance R3、R4Electric current when turning on for limit switch, protects preamplifying circuit.
In addition, the gain of preamplifying circuit is by input resistance RI, feedback resistance RFDetermine, and be set as gain control electricity
The maximum of road place system, to ensure that described gain control circuit has wide in range range of accommodation.Due to preamplifying circuit
For existing mature technology it is ensured that the feasibility of embodiment of the present invention.
Brief description
Fig. 1 is the structural representation of gain control circuit of the prior art；
Fig. 2 is the structural representation of the resistor network in gain control circuit of the prior art；
Fig. 3 is the structural representation of the gain control circuit according to first embodiment of the invention；
Fig. 4 is the control circuit of duty ratio according to first embodiment of the invention；
Fig. 5 is the structural representation of the gain control circuit according to second embodiment of the invention.
Specific embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with each reality to the present invention for the accompanying drawing
The mode of applying is explained in detail.However, it will be understood by those skilled in the art that in each embodiment of the present invention,
In order that reader more fully understands that the application proposes many ins and outs.But, even if there is no these ins and outs and base
In following embodiment many variations and modification it is also possible to realize each claim of the application technical side required for protection
Case.
The first embodiment of the present invention is related to a kind of gain control circuit, as shown in figure 3, this gain control circuit comprises
First resistor R1, second resistance R2, the 5th resistance RI1, the 6th resistance RF1, the 7th resistance RI2, the 8th resistance RF2, the first electric capacity C1、
Second electric capacity C2, the second difference transport and placing device, the 3rd difference transport and placing device and switch SW1.
Wherein, the 5th resistance RI1, the 6th resistance RF1, the 7th resistance RI2, the 8th resistance RF2Form with the second difference transport and placing device
Preamplifying circuit, receives audio signal and exports the prime signal of amplification.Described audio signal comprises positive audio signal
VIWith anti-phase audio signal-VI；Described prime signal packet prime containing positive signal VO1With anti-phase prime signal-VO1.Described prime
Amplifying circuit comprises two inputs and two outfans, and described two inputs are respectively positive audio signal input end, anti-
Phase audio signal input end, described two outfans are respectively positive prime signal output part, anti-phase prime signal output part.
Specifically, the 5th resistance RI1, the 7th resistance RI2For input resistance, the 6th resistance RF1, the 8th resistance RF2For feedback
Resistance；Second difference transport and placing device comprises an electrode input end, negative input, the first outfan and the second outfan.
5th resistance RI1One end is connected to described positive audio signal input end, and the negative pole that the other end is connected to the second difference transport and placing device is defeated
Enter end；6th resistance RF1One end is connected to the negative input of the second difference transport and placing device, and the other end is connected to the second difference amplifier
First outfan of device；7th resistance RI2One end is connected to described anti-phase audio signal input end, and it is poor that the other end is connected to second
Divide the electrode input end of transport and placing device；8th resistance RF2One end is connected to the electrode input end of the second difference transport and placing device, and the other end is even
It is connected to the second outfan of the second difference transport and placing device.
In the present embodiment, first resistor R1, second resistance R2, the first electric capacity C1, the second electric capacity C2Transport with the 3rd difference
Put device and constitute integrator circuit, receive output feedback signal and the prime signal of described preamplifying circuit output, and will be defeated
Go out to feed back signal and prime signal shaping and filtering and exported after subtracting each other.Output feedback signal comprises positive output feedback signal
VF1Feed back signal-VF with anti-phase output1.Integrator circuit comprises positive output feedback signal input, anti-phase output feedback letter
Number input, the first outfan and the second outfan；Described positive output feedback signal input and described positive prime signal
Outfan connects, and described anti-phase output feedback signal input terminal is connected with described anti-phase prime signal output part, and described first is defeated
Go out end and the second outfan by described shaping filter and the signal output subtracted each other.
Specifically, the 3rd difference transport and placing device comprise an electrode input end, negative input, the first outfan and
Second outfan；First electric capacity C1One end is connected to described positive output feedback signal input, and the other end is connected to integrator
The first outfan；Second electric capacity C2One end is connected to described anti-phase output feedback signal input terminal, and the other end is connected to integration
Second outfan of device；The negative input of the 3rd difference transport and placing device is connected to described positive output feedback signal input, the
The electrode input end of three difference transport and placing devices is connected to described anti-phase output feedback signal input terminal, and the first of the 3rd difference transport and placing device
Outfan is the first outfan of described integrator, and the second outfan of the 3rd difference transport and placing device is the second output of integrator
End.
In the present embodiment, switch SW1One end connect with described positive prime signal output part, the other end with described
Anti-phase prime signal output part connects.Switch SW1On or off control prime amplify signal decay.By controlling switch
SW1ON time is controlling the gain of gain control circuit.Therefore, do not need input resistance and anti-in this gain control circuit
Feed resistance segmentation in proportion, solve audio frequency power amplifier chip wiring difficult, it is to avoid during described regulation gain control circuit gain
" clicker " sound.
In the present embodiment, switch SW1By control circuit of duty ratio control, described control circuit of duty ratio is used for controlling
Described switch SW1On or off, as shown in figure 4, control circuit of duty ratio comprises buffer circuit and comparator.Buffer circuit
For the first difference transport and placing device；The positive pole of the just extremely buffer circuit of the first difference transport and placing device, the negative pole of the first difference transport and placing device is
The negative pole of buffer circuit, the outfan of the first difference transport and placing device is the outfan of buffer circuit.Buffer circuit receives outside regulation
Voltage VDAnd export the buffering signals of this external regulating voltage；Comparator receives the sawtooth waveforms V of fixed frequencySAWWith from described
The buffering signals of buffer circuit output.The output signal of control circuit of duty ratio is the output signal of comparator.By by outside
Adjust voltage VDWith sawtooth waveforms VSAWIt is compared, work as VD>VSAWWhen, VSAWFor low level；Conversely, working as VD<VSAWWhen, VSAWFor high electricity
Flat, reasonable disposition switchs SW1Turn-on and turn-off, the required duty specific damping of achievable gain control circuit place system increase
Benefit controls.By adjusting switch SW1Dutycycle come to control prime amplify signal the dough softening, thus realize to described gain control
The regulation of circuit gain.On the one hand, do not need input resistance and feedback resistance segmentation in proportion in described gain control circuit,
The audio frequency power amplifier chip wiring solving during physics realization is difficult.On the other hand, described gain control circuit adopts duty
The regulative mode of ratio, can realize step-less adjustment gain in certain limit, it is to avoid the appearance of " clicker " sound.
Therefore, in the present embodiment, by between positive prime signal output part and anti-phase prime signal output part
Connecting valve SW1, and pass through control circuit of duty ratio controlling switch SW1Dutycycle come to realize control gain control circuit gain,
So that avoiding input resistance and feedback resistance segmentation, solve audio frequency power amplifier chip wiring difficult, it is to avoid the described increasing of regulation
" clicker " sound during beneficial control circuit gain.
And, preamplifying circuit and integrator be existing mature technology it is ensured that embodiment of the present invention can
Row.
In addition, it is necessary to illustrate, the gain of preamplifying circuit is determined by input resistance, feedback resistance, in this enforcement
In mode, the gain of preamplifying circuit is set as the maximum of described gain control circuit place system, described to ensure
Gain control circuit has wide in range range of accommodation.
It is noted that the duty cycle circuit in present embodiment, a kind of simply concrete implementation mode, answer actual
With in, it would however also be possible to employ other equivalent circuit structures, here does not repeat one by one.
Second embodiment of the present invention is related to a kind of gain control circuit.Second embodiment is in first embodiment
On the basis of made to improve further, mainly the improvement is that, in second embodiment of the invention, also comprise 3rd resistor
R3, the 4th resistance R4, as shown in Figure 5.
In the present embodiment, resistance R3It is connected on switch SW1One end and described positive prime signal output part between；
Resistance R4It is connected on switch SW1The other end and described anti-phase prime signal output part between.Resistance R3、R4For limit switch
SW1Electric current during conducting, protects preamplifying circuit.
It will be understood by those skilled in the art that the respective embodiments described above are to realize the specific embodiment of the present invention,
And in actual applications, can to it, various changes can be made in the form and details, without departing from the spirit and scope of the present invention.
Claims (7)
1. a kind of gain control circuit is it is characterised in that comprise：Preamplifying circuit, switch and integrator circuit and dutycycle
Control circuit；
Described preamplifying circuit is used for the prime signal receiving audio signal and exporting amplification；Described audio signal comprises positive
Audio signal and anti-phase audio signal；Described prime signal packet prime containing positive signal and anti-phase prime signal；Described prime is put
Big circuit comprises two inputs and two outfans, and described two inputs are respectively positive audio signal input end, anti-phase
Audio signal input end, described two outfans are respectively positive prime signal output part, anti-phase prime signal output part；
One end of described switch is connected with described positive prime signal output part, the other end and described anti-phase prime signal output part
Connect；
Described integrator circuit is used for receiving the prime signal of output feedback signal and the output of described preamplifying circuit, and by institute
State output feedback signal and prime signal shaping and filtering and exported after subtracting each other；Wherein, described output feedback signal just comprises
Phase output feedback signal and anti-phase output feedback signal；
Described integrator circuit comprises positive output feedback signal input, anti-phase output feedback signal input terminal, the first output
End and the second outfan；Described positive output feedback signal input is connected with described positive prime signal output part, described anti-
Phase output feedback signal input is connected with described anti-phase prime signal output part, and described first outfan and the second outfan will
Described shaping filter and the signal output subtracted each other；
Described control circuit of duty ratio is used for controlling the on or off of described switch.
2. gain control circuit according to claim 1 is it is characterised in that described gain control circuit also comprises the 3rd electricity
Resistance and the 4th resistance；
Described 3rd resistor is connected between one end of described switch and described positive prime signal output part；
Described 4th resistant series are between the other end and described anti-phase prime signal output part of described switch.
3. gain control circuit according to claim 1 is it is characterised in that described control circuit of duty ratio comprises buffering electricity
Road and comparator；
Described buffer circuit receives external regulating voltage VDAnd export the buffering signals of this external regulating voltage；
Described comparator receives the sawtooth waveforms V of fixed frequencySAWWith the buffering signals exporting from described buffer circuit；
The positive pole input external voltage of described buffer circuit, the negative pole of this buffer circuit directly outfan company with this buffer circuit
Connect, the outfan of this buffer circuit is directly connected to the negative pole of described comparator, the positive pole of described comparator inputs described sawtooth
Ripple VSAW；
The output signal of described control circuit of duty ratio is the output signal of described comparator.
4. gain control circuit according to claim 3 is it is characterised in that described buffer circuit is the first difference amplifier
Device；
The positive pole of the just extremely described buffer circuit of described first difference transport and placing device, the negative pole of described first difference transport and placing device is institute
State the negative pole of buffer circuit, the outfan of described first difference transport and placing device is the outfan of described buffer circuit.
5. gain control circuit according to claim 1 is it is characterised in that described preamplifying circuit comprises the 5th electricity
Resistance, the 6th resistance, the 7th resistance, the 8th resistance and the second difference transport and placing device；
Described second difference transport and placing device comprises an electrode input end, negative input, first outfan and second export
End；
Described 5th resistance one end is connected to described positive audio signal input end, and the other end is connected to described second difference amplifier
The negative input of device；Described 6th resistance one end is connected to the negative input of described second difference transport and placing device, and the other end is even
It is connected to the first outfan of described second difference transport and placing device；Described 7th resistance one end is connected to described anti-phase audio signal input
End, the other end is connected to the electrode input end of described second difference transport and placing device；Described 8th resistance one end is connected to described second
The electrode input end of difference transport and placing device, the other end is connected to the second outfan of described second difference transport and placing device.
6. gain control circuit according to any one of claim 1 to 5 is it is characterised in that described preamplifying circuit
Gain be set as the maximum of described gain control circuit place system.
7. gain control circuit according to claim 1 is it is characterised in that described integrator circuit comprises the first electricity
Resistance, second resistance, the first electric capacity, the second electric capacity and the 3rd difference transport and placing device；
Described first resistor is connected between one end of described switch and described positive output feedback signal input；
Described second resistance is connected between the other end of described switch and described anti-phase output feedback signal input terminal；Described
Three difference transport and placing devices comprise an electrode input end, negative input, the first outfan and the second outfan；
Described first electric capacity one end is connected to described positive output feedback signal input, and the other end is connected to described integrator electricity
First outfan on road；Described second electric capacity one end is connected to described anti-phase output feedback signal input terminal, and the other end is connected to
Second outfan of described integrator circuit；
The negative input of described 3rd difference transport and placing device is connected to described positive output feedback signal input, and the described 3rd is poor
The electrode input end of point transport and placing device is connected to described anti-phase output feedback signal input terminal, and the first of described 3rd difference transport and placing device
Outfan is the first outfan of described integrator circuit, and the second outfan of described 3rd difference transport and placing device is described integrator
Second outfan of circuit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310317887.2A CN103441742B (en) | 2013-07-25 | 2013-07-25 | Gain control circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310317887.2A CN103441742B (en) | 2013-07-25 | 2013-07-25 | Gain control circuit |
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| Publication Number | Publication Date |
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| CN103441742A CN103441742A (en) | 2013-12-11 |
| CN103441742B true CN103441742B (en) | 2017-03-08 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101340244A (en) * | 2008-08-08 | 2009-01-07 | 宁波环球广电科技有限公司 | Optical receiving module |
| CN203590168U (en) * | 2013-07-25 | 2014-05-07 | 上海智浦欣微电子有限公司 | Gain control circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102545800B (en) * | 2010-12-29 | 2015-09-23 | 意法半导体研发(深圳)有限公司 | The circuit of amplifying signal and method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101340244A (en) * | 2008-08-08 | 2009-01-07 | 宁波环球广电科技有限公司 | Optical receiving module |
| CN203590168U (en) * | 2013-07-25 | 2014-05-07 | 上海智浦欣微电子有限公司 | Gain control circuit |
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