CN104767498B - Gain control method and device - Google Patents
Gain control method and device Download PDFInfo
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- CN104767498B CN104767498B CN201510219178.XA CN201510219178A CN104767498B CN 104767498 B CN104767498 B CN 104767498B CN 201510219178 A CN201510219178 A CN 201510219178A CN 104767498 B CN104767498 B CN 104767498B
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Abstract
A kind of gain control method and device, methods described include：Gather the output signal of amplifier；When it is determined that when the output signal zero crossing or adjacent interval in the zero crossing, controlling the corresponding gain signal of AGC control circuit outputs, the gain of the amplifier being controlled by gain control circuit.Above-mentioned scheme can improve the quality of music.
Description
Technical field
The present invention relates to gain control field, more particularly to a kind of gain control method and device.
Background technology
Audio-frequency power amplifier, is that audio signal is carried out into power amplification, the purpose that amplifies is reached with drive the speaker.
In order to lift the effect of music, increase the loudness of music, the most band of current audio-frequency power amplifier
There is automatic growth control (Automatic Gain Control, AGC) function.With the increase of input signal, power output with
Increase, AGC detect power output exceed setting startup threshold value after, actively reduce the gain inside power amplifier,
By output power limit under the power threshold of setting；When input signal reduces, power output is reduced to the release threshold of setting
After value, AGC actively recovers the gain inside power amplifier, and the output of power amplifier is limited within the power bracket of setting.
A kind of gain control method of the prior art, can be more than predetermined work(in the power output for detecting amplifier
During rate threshold value, power output is maintained to the power threshold of setting.But, the AGC control circuits in audio-frequency power amplifier exist
Change gain at the peak value of output amplitude and introduce certain noise, have impact on music effect, certain noise can be produced,
Accordingly, there exist the problem of music file play quality difference, the usage experience of user has been had a strong impact on.
The content of the invention
What the embodiment of the present invention was solved is the play quality for lifting music file.
To solve the above problems, the embodiments of the invention provide a kind of gain control method, methods described includes：
Gather the output signal of amplifier；
When it is determined that when the output signal zero crossing or adjacent interval in the zero crossing, control AGC control circuits
Corresponding gain signal is exported, the gain of the amplifier is controlled by gain control circuit.
Alternatively, the determination output signal zero crossing includes：
The output signal is compared with default common mode electrical level；
When it is determined that the output signal is equal with the common mode electrical level, the output signal zero crossing is determined.
Alternatively, the determination output signal is in the adjacent interval of the zero crossing, including：
The output signal is compared with default first threshold level and Second Threshold level, the first threshold
Level is more than the common mode electrical level, and the Second Threshold level is less than the common mode electrical level；
When it is determined that the output signal is more than the Second Threshold level, less than the first threshold level, and being not equal to
During the common mode electrical level, determine that the output signal is in the adjacent interval of the zero crossing.
The embodiment of the present invention additionally provides a kind of gain control, and described device includes：
Collecting unit, the output signal suitable for gathering amplifier；
Zero cross detection circuit, suitable for judge the output signal whether zero crossing or adjacent region in the zero crossing
Between, and when determining the output signal zero crossing or the adjacent interval in the zero crossing, control AGC controls circuit to gain
Circuit is controlled to input corresponding gain signal；
AGC controls circuit, suitable for input signal is compared with default detection level threshold, and according to comparative result
Export corresponding gain signal；
Gain control circuit, suitable for the gain according to the gain signal of the AGC control circuit outputs to the amplifier
It is controlled.
Alternatively, the zero cross detection circuit includes the first detection circuit and the second detection circuit；
The first detection circuit, suitable for the output signal is compared with default common mode electrical level；When it is determined that institute
State output signal it is equal with the common mode electrical level when, export the first control signal, first control signal be suitable to control AGC control
Circuit processed exports corresponding gain signal, the gain by gain control circuit to the amplifier to the gain control circuit
It is controlled；
The second detection circuit, suitable for by the output signal and default first threshold level and Second Threshold level
It is compared, when it is determined that the output signal is more than the Second Threshold level, less than the first threshold level, and being not equal to
During the common mode electrical level, the second control signal is exported, second control signal is suitable to control AGC and controls circuit to the gain
The corresponding gain signal of control circuit output, is controlled by gain control circuit to the gain of the amplifier, wherein, institute
State first threshold level and the Second Threshold level is respectively greater than and less than the common mode electrical level；
It is described first detection circuit output end and it is described second detection circuit output end respectively with an OR gate arithmetic element
First output end and the coupling of the second output end, the output end of the OR gate arithmetic element and the control end coupling of the controlling switch
Connect, and the input of controlling switch and the AGC control the output end of circuit to couple, the output end of the controlling switch with it is described
The input coupling of gain control circuit.
Alternatively, the first detection circuit includes：First comparator, delay cell and XOR gate；
The positive input of the first comparator is coupled with the output signal, reverse input end and the common mode electrical level
Coupling, output end is coupled with the first input end of the delay cell and the XOR gate respectively；
The output end of the delay cell and the second input of the XOR gate are coupled；
Second input of the XOR gate and the first input end of the OR gate arithmetic element are coupled.
Alternatively, the second detection circuit includes：Second comparator, the 3rd comparator and with door arithmetic element；
The positive input of second comparator is coupled with the first threshold level, reverse input end and the output
Signal is coupled, and output end is coupled with the first input end with door arithmetic element；
The positive input of 3rd comparator is coupled with the output signal, reverse input end and the Second Threshold
Level is coupled, and output end is coupled with second input with door arithmetic element；
It is described to be coupled with the output end of door arithmetic element with the second input of the OR gate arithmetic element.
Alternatively, the AGC controls circuit includes amplitude detection circuit and AGC control circuits, wherein：
The amplitude detection circuit, suitable for the output signal is compared with default detection threshold level, when true
When the fixed output signal is more than default detection threshold level, control in the AGC controls circuit forward-backward counter according to
Default first clock signal frequency carries out appreciation counting；When it is determined that the output signal is less than default detection threshold level
When, control forward-backward counter in the AGC controls circuit to carry out depreciation counting according to default second clock signal frequency.
The AGC sequential control circuits, suitable for exporting gain signal corresponding with the count value of the forward-backward counter.
Compared with prior art, technical scheme has the following advantages that：
It is determined that amplifier output signal zero crossing or adjacent interval in the zero crossing when, controlled by AGC
The gain of circuit and gain control circuit processed to amplifier is controlled, rather than the increasing at the peak value of output signal to amplifier
Benefit is adjusted, and can prevent output signal from going out the phenomenon fallen in peak value, so as to eliminate the noise thus introduced,
It is thus possible to improve music effect.
Brief description of the drawings
Fig. 1 is the oscillogram of the average broadcast sound volume for the music file that peak amplitude is 0dB；
Fig. 2 is the oscillogram of the average broadcast sound volume for the music file that peak amplitude is -12dB；
Fig. 3 is the oscillogram of the average broadcast sound volume for the music file that peak factor is 9dB；
Fig. 4 is the oscillogram of the average broadcast sound volume for the music file that peak factor is 19dB；
Fig. 5 a and Fig. 5 b are the oscillogram of the output signal of 40ms and 5ms startup time corresponding amplifier respectively；
Fig. 6 a and Fig. 6 b are a kind of structural representations of gain control of the prior art；
Fig. 7 is the output signal of amplifier of the prior art and the waveform diagram of gain；
Fig. 8 is a kind of structural representation of gain control in the embodiment of the present invention；
Fig. 9 is the circuit diagram of the zero cross detection circuit in a kind of gain control in the embodiment of the present invention；
Figure 10 is a kind of flow chart of gain control method in the embodiment of the present invention；
Figure 11 is the relation schematic diagram between the input signal and output signal of the first detection circuit；
Figure 12 is the relation schematic diagram between the input signal and output signal of the second detection circuit；
Figure 13 is the output signal and the ripple of gain of the amplifier after the gain control method regulation during the present invention is implemented
Shape schematic diagram.
Embodiment
When playing music, it is found that the average volume difference of different music files is very big, there is two reasons, and one is peak
Value amplitude is different, and two be that peak factor is different.
Figures 1 and 2 show that the schematic diagram of the average volume of the same a piece of music of different peak amplitudes.Wherein, Fig. 1 middle pitches
The peak amplitude of music file is that the peak amplitude of music file broadcasting in 0dB, Fig. 2 is -12dB.
Fig. 3 and Fig. 4 show the volume schematic diagram of the music file of different peak factors.Music file in wherein Fig. 3
Peak factor is that the peak factor of music file in 9dB, Fig. 4 is 19dB.
In specific implementation, peak factor can be calculated using formula below：
Wherein, Crestfactor represents peak factor, PpeakRepresent the peak power that music file is played, PAVGRepresent sound
The mean power that music file is played.
It was found from above-mentioned analysis, in the case of ceteris paribus, average volume of the music file when playing, with
The increase of peak amplitude and increase, reduce with the increase of peak factor.
In actual applications, audio power amplification system has default spiking output, the spiking output
Typically determined by the supply voltage of the audio power amplification system, if output exceedes the spiking output, Jiu Huifa
Raw truncation distortion.
Specific to refer in Fig. 5 a and shown in Fig. 5 b, the 500a in wherein Fig. 5 a is the region of generation truncation distortion, Fig. 5 b
In 500b for occur truncation distortion region.Therefore, the startup time is longer, and volume can be larger, but truncation distortion also can be therewith
Increase；If the time of startup is shorter, truncation distortion can be reduced therewith, but volume can be reduced.
In the prior art, in order to lift the result of broadcast of music, the loudness of music, current audio-frequency amplifier are increased
Automatic growth control (Automatic Gain Control, AGC) function is carried mostly, similar to the work done during compression in audio effect processing
Energy or amplitude limit function.With the increase of input signal, output signal increases therewith, and AGC is detecting output signal more than setting
Startup threshold value after, output signal is limited under the predetermined threshold value of setting by the gain inside active step-down amplifier；When defeated
Enter signal reduction, output signal is reduced to after the release threshold value of setting, and AGC actively recovers the gain inside power amplifier, by amplifier
Output be limited within the power bracket of setting.Wherein, the time of gain reduction is the AGC startup time, gain recovery
Time is AGC release time, specifically refers to Fig. 6 a and 6b.
As shown in figure 6 a and 6b, a kind of gain control circuit of the prior art, amplitude detection circuit 501 is to amplifier
502 output signal Vout are monitored, after output signal Vout exceeds default detection threshold level, amplitude detection circuit
The 501 corresponding control signals of output, the first path of control MUX gate circuits 503 is opened, into AGC sequential control circuits 504
The input of forward-backward counter 5041 starts time clock signal so that forward-backward counter 5041 is according to the startup time clock
The signal frequency f of signal1Appreciation counting is carried out, the AGC control outputs of circuit 505 are corresponding with the count value of forward-backward counter 5041
Gain signal, by the gain of the gradually droop amplifier 502 of gain control circuit 506, output signal Vout is reached and is tieed up
Hold in detection threshold level.
After output signal Vout is less than the detection threshold level, the output release time clock of amplitude detection circuit 501
Signal, amplitude detection circuit 501 exports corresponding control signal, and the alternate path of control MUX gate circuits 503 is opened, to plus-minus
Method counter 5041 inputs release time clock signal so that forward-backward counter 5041 is according to the release time clock signal
Frequency f2Depreciation counting is carried out, AGC control circuits 505 export gain letter corresponding with the count value of forward-backward counter 5041
Number, gradually recover the gain of amplifier 502 by gain control circuit 506, output signal Vout is maintained default scope
Within.
Shown in Figure 7, existing gain control exceedes default threshold in the amplitude for detecting output signal Vout
After value, start to change the internal gain of power amplifier so that the change of the gain 71 of amplifier occurs at the peak value of output amplitude, this
" falling " of output signal will be caused, specifically referred in Fig. 7 shown in the 701-707 of region.To voice signal, in general
Change within 1dB is not easy to discover, but to some specific music, if its frequency is relatively simple, just can hear
The noise produced during Gain tuning.Therefore, AGC of the prior art control circuit go out to change gain in the peak value of output amplitude and
Certain noise is introduced, music effect is have impact on.
To solve the above-mentioned problems in the prior art, the technical scheme that the embodiment of the present invention is used passes through it is determined that putting
When the output signal zero crossing of big device or adjacent interval in the zero crossing, pass through AGC and control circuit and gain to control
Gain of the circuit to amplifier is controlled, rather than the gain to amplifier at the peak value of output signal is adjusted, can be with
Prevent output signal from going out the phenomenon fallen in peak value, the noise thus introduced can be eliminated, improve music effect.
It is understandable to enable the above objects, features and advantages of the present invention to become apparent, below in conjunction with the accompanying drawings to the present invention
Specific embodiment be described in detail.
Fig. 8 shows a kind of structural representation of gain control in the embodiment of the present invention.Gain as shown in Figure 1
Control device, can include collecting unit (not shown), zero cross detection circuit 801, AGC control circuits 802 and gain control
Circuit 803 processed, wherein, the output end of amplifier 800 controls circuit 802 with the input and AGC of zero cross detection circuit 801 respectively
Input coupling, the output end of zero cross detection circuit 801 controls the output end of circuit 802 to couple with AGC, AGC control circuits
802 output end is also coupled with the input of gain control circuit 803, output end and the amplifier 800 of gain control circuit 803
Coupling.Wherein：
Collecting unit, the output signal suitable for gathering amplifier.
Zero cross detection circuit 801, suitable for judge the output signal whether zero crossing or in the adjacent of the zero crossing
Interval, and when determining the output signal zero crossing or the adjacent interval in the zero crossing, control AGC controls circuit to increasing
Benefit control circuit inputs corresponding gain signal.
AGC controls circuit 802, suitable for input signal is detected into level threshold is compared with default, and according to comparing
As a result corresponding gain signal is exported.In an embodiment of the present invention, the AGC controls circuit 802 includes amplitude detection circuit
8021 and AGC sequential control circuits 8022.Wherein, the amplitude detection circuit 8021, suitable for by the output signal with it is default
Detection threshold level be compared, when it is determined that the output signal be more than default detection threshold level when, control AGC sequential
Forward-backward counter in circuit 8032 is controlled to carry out appreciation counting according to default first clock signal frequency；When it is determined that described defeated
When going out signal less than default detection threshold level, control in the AGC sequential control circuits 8022 forward-backward counter according to
Default second clock signal frequency carries out depreciation counting；The sequential AGC controls circuit 8022, suitable for output and the plus-minus
The corresponding gain signal of count value of method counter.
Gain control circuit 803, suitable for the increasing according to the gain signal of the AGC control circuit outputs to the amplifier
Benefit is controlled.
Shown in Figure 9, in an embodiment of the present invention, zero cross detection circuit includes the first detection circuit 901, second
Detect circuit 902, controlling switch (not shown) and OR gate arithmetic element 903.The output end of the first detection circuit 901
The first output end and the second output end coupling of the output end of circuit 902 respectively with OR gate arithmetic element 903 are detected with described second
Connect, the output end of OR gate arithmetic element 903 and the control end of controlling switch are coupled, and the input of controlling switch and the AGC
The output end coupling of circuit is controlled, the output end of controlling switch and the input of gain control circuit are coupled.Wherein：
First detection circuit 901, suitable for the output signal is compared with default common mode electrical level；When it is determined that described
When output signal is equal with the common mode electrical level, the first control signal is exported, first control signal is suitable to control AGC controls
Circuit exports corresponding gain signal to the gain control circuit, and the gain of the amplifier is entered by gain control circuit
Row control.
Second detection circuit 902, suitable for by the output signal and default first threshold level and Second Threshold level
It is compared, when it is determined that the output signal is more than the Second Threshold level, less than the first threshold level, and being not equal to
During the common mode electrical level, the second control signal is exported, second control signal is suitable to control AGC and controls circuit to the gain
The corresponding gain signal of control circuit output, is controlled by gain control circuit to the gain of the amplifier, wherein, institute
State first threshold level and the Second Threshold level is respectively greater than and less than the common mode electrical level.
Continuing with shown in Figure 9, in an embodiment of the present invention, the first detection circuit 901 includes first comparator
9011st, delay cell 9012 and XOR gate 9013.Wherein, the positive input of first comparator 9011 and the output signal coupling
Connect, reverse input end is coupled with the common mode electrical level, output end is defeated with the first of delay cell 9012 and XOR gate 9013 respectively
Enter end coupling；The output end of delay cell 9012 is coupled with the second input of XOR gate 9013；The second of XOR gate 9013 is defeated
Enter end and the first input end of OR gate arithmetic element is coupled.
In an embodiment of the present invention, the second detection circuit 902 includes the second comparator 9021, the 3rd comparator
9022 and with door arithmetic element 9023.Wherein, the positive input of the second comparator 9021 is coupled with the first threshold level,
Reverse input end is coupled with the output signal, and output end with the first input end of door arithmetic element 9023 with coupling；3rd ratio
Positive input compared with device 9022 is coupled with the output signal, and reverse input end is coupled with the Second Threshold level, output
End with the second input of door arithmetic element 9023 with coupling；With the output end and OR gate arithmetic element of door arithmetic element 9023
903 the second input coupling.
The operation principle of the gain control shown in Fig. 8 and 9 is further described in detail with reference to Figure 10.
Figure 10 shows a kind of flow chart of gain control method in the embodiment of the present invention.Gain control as shown in Figure 10
Method processed, can include：
Step S1001：Gather the output signal of amplifier.
In specific implementation, after the music signal of input is handled by amplifier, exported as the output signal Vout.
Step S1002：Judge the output signal zero crossing or the adjacent interval in the zero crossing, work as judged result
During to be, step S1003 can be performed, conversely, not performing any action then.
In specific implementation, judge amplifier output signal Vout whether zero crossing when, can be first by collection
The output signal Vout of amplifier is compared with default common mode electrical level；When it is determined that the output signal Vout and the common mode
When level is equal, the output signal Vout zero crossings are determined.
In an embodiment of the present invention, using first detection circuit come judge amplifier output signal Vout whether zero passage
Point, specifically refers to Fig. 9.
As shown in figure 9, the first comparator 9011 in the first detection circuit 901 is by the output signal Vout of amplifier and in advance
If common mode electrical level be compared the corresponding signal of output, XOR gate 9013 is by the comparison signal of the output of first comparator 9011
The delay comparison signal obtained after the processing of delay cell 9012, the comparison signal exported with first comparator 9011 is carried out
After corresponding processing, the first control signal is exported.Wherein, as input signal amplifier output signal Vout and common mode electricity
Relation between flat and the first detection circuit 901 output signal, it is specific shown in Figure 11.
It was found from Fig. 8, Fig. 9 and Figure 11, when the output signal Vout of amplifier 800 is equal with default common mode electrical level,
First detection circuit 901 can export high level.Now, no matter which kind of level signal is the second detection circuit 902 output signal be, the
The high level that one detection circuit 901 is exported will all export high level after by the computing of OR gate arithmetic element 804.
In specific implementation, the adjacent interval of the zero crossing whether is in the output signal Vout for judging amplifier,
It that is to say whether the output signal Vout for judging amplifier is near zero-crossing point, can be by the output signal Vout with presetting
First threshold level and Second Threshold level be compared, when it is determined that the output signal be more than the Second Threshold level,
Less than the first threshold level, and when being not equal to the common mode electrical level, determine that the output signal Vout is in the zero passage
The adjacent interval of point.Wherein, the first threshold level is more than the common mode electrical level, and the Second Threshold level is less than described common
Mould level.
In an embodiment of the present invention, judge whether the output signal Vout of amplifier is in using the second detection circuit
The adjacent interval of zero crossing, specifically refers to Fig. 9.
As shown in figure 9,902 the second comparator 9021 is by output signal Vout and default first in the second detection circuit
Threshold level compares, and exports the first comparison signal.902 the 3rd comparator 9022 is by output signal in second detection circuit
Vout is compared with default Second Threshold level, and exports the second comparison signal.With door arithmetic element 9023 by the second comparator
First comparison signal of 9021 outputs and the second comparison signal of the 3rd comparator 9022 output are done with after computing, exporting to OR gate
Arithmetic element 804.Wherein, as input signal amplifier 800 output signal Vout, first threshold level, Second Threshold
Relation between the output signal of level and the second detection circuit 902, it is specific shown in Figure 12.
It was found from Fig. 8, Fig. 9 and Figure 12, as the output signal Vout of amplifier and in first threshold level and Second Threshold
Between level, when it is not equal to common mode electrical level, the second detection circuit 902 can export high level.Now, no matter the second detection circuit
Which kind of level signal is 902 output signals be, the high level that the second detection circuit 902 is exported is transported by OR gate arithmetic element 804
After calculation, high level will be all exported.
Step S1003：The corresponding gain signal of AGC control circuit outputs is controlled, is put by gain control circuit to described
The gain of big device is controlled.
In specific implementation, it is determined that the output signal Vout zero crossings or adjacent interval in zero crossing of amplifier
When, it is allowed to the gain to amplifier is adjusted, and allows the corresponding gain signal of AGC control circuit outputs, passes through gain control
Gain of the circuit processed to the amplifier is controlled.
Continuing with referring to shown in Fig. 8 and 9, the first detection circuit 901 is it is determined that the output signal Vout zero passages of amplifier 800
High level is exported during point, the second detection circuit 902 is it is determined that the output signal Vout of amplifier 800 is in the phase of the zero crossing
Neighboring interval, can also export high level.The height that the high level or the second detection circuit 902 that first detection circuit 901 is exported are exported
Level, the same output high level after OR gate arithmetic element 903.The high level that OR gate arithmetic element 903 is exported will be opened and controlled
System switch so that the gain signal input-gain control circuit 803 that AGC control circuits 802 are exported, gain control circuit 803 will
Gain of the gain signal that circuit 802 is exported to amplifier 800 is controlled to be adjusted according to AGC.
Specifically, when AGC controls the amplitude detection circuit 8021 in circuit 802, the output of amplifier 800 is believed
Number Vout is compared with default detection threshold level, when it is determined that the output signal Vout is more than default detection threshold value electricity
Usually, forward-backward counter (not shown) is controlled in AGC control circuit 802 according to default first clock signal frequency
Rate carries out appreciation counting；When it is determined that the output signal Vout is less than default detection threshold level, the middle plus-minus is controlled
Method counter carries out depreciation counting according to default second clock signal frequency.The AGC sequential control circuits 8022 are then exported
Gain signal corresponding with the count value of the forward-backward counter.
Figure 13 shows the relation between the output signal Vout and amplifier of amplifier gain 131.Refer to Figure 13
It is shown, the gain control method and device of the embodiment of the present invention it is determined that amplifier output signal Vout zero crossings or be in
During the adjacent interval of the zero crossing, the gain of circuit and gain control circuit to amplifier is controlled to be controlled by AGC, and
The non-gain at output signal Vout peak value to amplifier is adjusted, and can prevent output signal Vout from being sent out at peak value
The raw phenomenon fallen, so as to eliminate the noise thus introduced, it is thus possible to improve music effect.
One of ordinary skill in the art will appreciate that all or part of step in the various methods of above-described embodiment is can
To instruct the hardware of correlation to complete by program, the program can be stored in computer-readable recording medium, and storage is situated between
Matter can include：ROM, RAM, disk or CD etc..
The method and system to the embodiment of the present invention have been described in detail above, and the present invention is not limited thereto.Any
Art personnel, without departing from the spirit and scope of the present invention, can make various changes or modifications, therefore the guarantor of the present invention
Shield scope should be defined by claim limited range.
Claims (4)
1. a kind of gain control, it is characterised in that including：
Collecting unit, the output signal suitable for gathering amplifier；
Zero cross detection circuit, suitable for judge the output signal whether zero crossing or adjacent interval in the zero crossing, and
When it is determined that the output signal zero crossing or adjacent interval in the zero crossing, control AGC control circuit to gain control
Circuit inputs corresponding gain signal；
AGC controls circuit, suitable for input signal is compared with default detection level threshold, and is exported according to comparative result
Corresponding gain signal；
Gain control circuit, is carried out suitable for the gain signal according to the AGC control circuit outputs to the gain of the amplifier
Control；
Wherein, the zero cross detection circuit includes the first detection circuit, the second detection circuit, controlling switch and OR gate computing list
Member；
The first detection circuit, suitable for the output signal is compared with default common mode electrical level；When it is determined that described defeated
Go out signal it is equal with the common mode electrical level when, export the first control signal, first control signal be suitable to control AGC control electricity
Gain control circuit described in road direction exports corresponding gain signal, and the gain of the amplifier is carried out by gain control circuit
Control；
The second detection circuit, suitable for the output signal and default first threshold level and Second Threshold level are carried out
Compare, when it is determined that the output signal is more than the Second Threshold level, less than the first threshold level, and be not equal to described
During common mode electrical level, the second control signal is exported, second control signal is suitable to control AGC control circuits and controlled to the gain
The corresponding gain signal of circuit output, is controlled by gain control circuit to the gain of the amplifier, wherein, described
One threshold level and the Second Threshold level are respectively greater than and less than the common mode electrical level；
The first detection circuit output end and the second detection circuit output end respectively with the OR gate arithmetic element the
One input and the coupling of the second input, the output end of the OR gate arithmetic element are coupled with the control end of the controlling switch,
And the input of controlling switch controls the output end of circuit to couple with the AGC, the output end of the controlling switch increases with described
The input coupling of benefit control circuit.
2. gain control according to claim 1, it is characterised in that the first detection circuit includes：First ratio
Compared with device, delay cell and XOR gate；
The positive input of the first comparator is coupled with the output signal, reverse input end and the common mode electrical level coupling
Connect, output end is coupled with the first input end of the delay cell and the XOR gate respectively；
The output end of the delay cell and the second input of the XOR gate are coupled；
The first input end of the output end of the XOR gate and the OR gate arithmetic element is coupled.
3. gain control according to claim 1 or 2, it is characterised in that the second detection circuit includes：Second
Comparator, the 3rd comparator and with door arithmetic element；
The positive input of second comparator is coupled with the first threshold level, reverse input end and the output signal
Coupling, output end is coupled with the first input end with door arithmetic element；
The positive input of 3rd comparator is coupled with the output signal, reverse input end and the Second Threshold level
Coupling, output end is coupled with second input with door arithmetic element；
It is described to be coupled with the output end of door arithmetic element with the second input of the OR gate arithmetic element.
4. gain control according to claim 1, it is characterised in that the AGC controls circuit includes amplitude detection
Circuit and AGC sequential control circuits, wherein：
The amplitude detection circuit, suitable for the output signal is compared with default detection threshold level, when it is determined that institute
When stating output signal more than default detection threshold level, control in the AGC sequential control circuits forward-backward counter according to
Default first clock signal frequency carries out appreciation counting；When it is determined that the output signal is less than default detection threshold level
When, control forward-backward counter in the AGC sequential control circuits to carry out depreciation meter according to default second clock signal frequency
Number；
The AGC sequential control circuits, suitable for exporting gain signal corresponding with the count value of the forward-backward counter.
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| CN201510219178.XA CN104767498B (en) | 2015-04-30 | 2015-04-30 | Gain control method and device |
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| CN105099385B (en) * | 2015-08-24 | 2018-07-10 | 上海艾为电子技术股份有限公司 | Gain control circuit and audio frequency apparatus |
| CN106448712B (en) * | 2016-10-20 | 2019-06-25 | 广州视源电子科技股份有限公司 | Automatic gain control method and device for audio signal |
| CN106656085B (en) * | 2017-01-20 | 2018-09-25 | 深圳市中移联半导体科技有限公司 | A kind of gain control |
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| CN110212871B (en) * | 2019-06-12 | 2022-03-22 | 上海艾为电子技术股份有限公司 | Audio power amplifier and gain control circuit and control method thereof |
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