CN102801396A - Automatic gain adjustment circuit in audio system - Google Patents
Automatic gain adjustment circuit in audio system Download PDFInfo
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- CN102801396A CN102801396A CN2012103352037A CN201210335203A CN102801396A CN 102801396 A CN102801396 A CN 102801396A CN 2012103352037 A CN2012103352037 A CN 2012103352037A CN 201210335203 A CN201210335203 A CN 201210335203A CN 102801396 A CN102801396 A CN 102801396A
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Abstract
The invention discloses an automatic gain adjustment circuit in an audio system. The automatic gain adjustment circuit comprises a level comparator unit and a gain reduction unit, wherein two input ends of the level comparator unit respectively input an output signal of the audio system and the preset reference voltage; the level comparator unit compares the two input signals to output a control signal to the gain reduction unit; the gain reduction unit judges whether the gain reduction is performed and the amplitude of the gain is reduced according to the input control signal; and the output end of the gain reduction unit serves as the output end of the automatic gain adjustment circuit. According to the adjustment circuit, by adoption of the level comparator unit, the amplification of the input signal can be met to the greatest degree, and the gain of a large input signal is timely reduced; the linearity is high, and extra nonlinear distortion is not introduced; and moreover, the controllability is high, the controlled level is changed by adjusting the preset reference voltage, and the control time is changed by adjusting the parameters of the time setting unit.
Description
Technical field
The invention belongs to technical field of integrated circuits, be specifically related to a kind of audio system that is used for the self-regulating circuit of audio frequency output gain.
Background technology
In audio system, voice signal amplifies through power amplifier, drives loud speaker or earphone then.When the dynamic range of voice signal is bigger, just necessarily require the system can be enough sensitive to small signal, make that loud speaker can clear recognition reaction; Necessarily require it to make the output of loud speaker be unlikely to distortion again to bigger signal reaction appropriateness.The former has enough big gain by the required power amplifier, tiny signal is amplified to the degree that can drive loud speaker; Latter's required power Amplifier Gain is enough low, can not surpass saturation voltage than large-signal through amplifying its amplitude of back.Therefore, be necessary to provide a kind of and can guarantee, suppress gain adjusting circuit simultaneously than the large-signal gain than small signal gain.
Obviously the theory of robust designs can apply to here; The signal that finally amplifies output is sampled prime; Size through sampled signal identification output voltage; With actual demand kinetic-control system gain, but this method must satisfy the requirement of initial control level simultaneously, promptly exports signal and reaches much level and begin the droop amplifier gain.
Typical method is to carry out bypass at input with a diode or triode, and they receive the control shunting input signal of output feedback signal.Signal is big more when exporting, and its equivalent AC impedance is more little, and is big more to the shunting action of input signal, to reach the effect that reduces the large-signal gain.These class methods have realized the large-signal gain controlling merely; But there are two bigger problems: the first, also have certain electric current when considering the diode voltage and flow through less than the conducting voltage of PN junction, the initial control level of this method is quite little; To decay is in various degree arranged than small signal gain; Be unfavorable for the amplification than small-signal, the waste Amplifier Gain makes the sound of loudspeaker plays not have stereovision; The second, because this interchange equiva lent impedance is non-linear, will cause extra nonlinear distortion at the audio signal amplification process, the result is that the adding of bypass circuit makes the degradation of whole amplifier.
Summary of the invention
In view of above content, the invention provides a kind of the simple in structure of audio system and circuit of gaining of resonance-amplifier automatically of being used for, this circuit has the good linearity; Basic principle is: when the output signal of audio system hour; Gain adjusting circuit is not worked, and makes full use of Amplifier Gain, and it is enough amplified; When the output of audio system is big; If the output signal is greater than the value of setting, gain adjusting circuit is just started working, and linear decay is carried out in the gain of pair amplifier.
Technical scheme of the present invention is: a kind of gain automatic regulating circuit that is used for audio system; Specifically comprise: level comparator unit and gain reduction unit; The reference voltage that two inputs of described level comparator unit are imported the output signal of audio system respectively and are provided with in advance, the level comparator unit compares one of output to two signals importing and controls signal to the gain reduction unit; The amplitude that the gain reduction unit judges whether to carry out gain reduction and decay gain according to the control signal of input, gain reduction unit output is as the output of said gain automatic regulating circuit.
Further; Said gain automatic regulating circuit also comprises: the time is provided with the unit; The described time is provided with the unit and is used for setting and starts to control the time; Saidly start to control the time for from the output signal of audio system during greater than the reference voltage that is provided with in advance, to the time that gain automatic regulating circuit begins to carry out gain reduction, its input is used to import the control signal of described level comparator unit output.
As a preferred version; Described level comparator unit; Comprise: NPN pipe NPN9, NPN10, NPN11, PNP pipe PNP8, PNP9, concrete annexation is: the base stage of NPN pipe NPN10 is used for input as the first input end of described level comparator unit and treats conditioning signal; The emitter of the collector electrode of NPN10, the emitter of PNP8 and PNP pipe PNP9 is connected to outside supply voltage; The emitter of the emitter of NPN pipe NPN10, NPN pipe NPN11 is connected with the collector electrode of NPN pipe NPN9, and the base stage of NPN pipe NPN11 is used to import the reference voltage that is provided with in advance as second input of described level comparator unit, and the collector electrode of NPN pipe NPN11 is connected to the collector electrode of PNP pipe PNP8; The base stage of NPN pipe NPN9 is connected to outside bias voltage; The emitter of NPN pipe NPN9 is connected to ground, and the base stage of PNP pipe PNP8, collector electrode are connected with the base stage of PNP pipe PNP9, and the collector electrode of PNP pipe PNP9 is as the output of described level comparator unit.
As another preferred version; Described gain reduction unit; Comprise: NPN pipe NPN1, NPN2, NPN3, NPN4, NPN5, NPN6, NPN7, NPN8, NPN9, PNP pipe PNP1, PNP2, PNP3, PNP4, PNP5, PNP6, PNP7, and resistance R 1, R2, R3, R4; Concrete annexation is: an end of resistance R 1 is as the input of described gain reduction unit, and the other end of resistance R 1 is connected with the collector electrode of NPN pipe NPN1, the base stage of NPN1, the base stage of NPN2; The emitter of NPN pipe NPN1 is connected to the collector electrode of NPN pipe NPN3; The emitter of NPN pipe NPN2 is connected to the collector electrode of NPN pipe NPN3; Resistance R 2 is connected between NPN pipe NPN2 collector electrode and the PNP pipe PNP1 collector electrode; Base stage and the collector electrode short circuit of NPN pipe NPN3; Resistance R 3 is connected between the emitter and ground of NPN pipe NPN3; The base stage of the base stage of PNP pipe PNP1, the collector electrode of PNP1, PNP pipe PNP2 is connected; The emitter of the collector electrode of the emitter of PNP pipe PNP1, the emitter of PNP2, NPN pipe NPN9, the emitter of PNP pipe PNP4, PNP pipe PNP7, the emitter of PNP pipe PNP5 are connected to outside supply voltage, and the collector electrode of PNP pipe PNP2 is connected to the collector electrode of NPN pipe NPN4, and the base stage of the base stage of NPN pipe NPN4, the collector electrode of NPN4, NPN pipe NPN5 is connected with the base stage of NPN pipe NPN6; The collector electrode that the emitter of the emitter of NPN pipe NPN4, NPN pipe NPN5 all is connected to ground, NPN pipe NPN5 is connected to the emitter of NPN pipe NPN9; The base stage of NPN pipe NPN9 is connected to the collector electrode of PNP pipe PNP3, and the base stage of the base stage of PNP pipe PNP3, the collector electrode of PNP3, PNP pipe PNP4 is connected, and the collector electrode of PNP pipe PNP4 is connected to the base stage of NPN pipe NPN7; The base stage of PNP pipe PNP7 is connected to the base stage of PNP pipe PNP3; The collector electrode of the base stage of NPN pipe NPN8, the collector electrode of NPN8 and PNP pipe PNP7 is connected and as the output of described gain reduction unit, the base stage of NPN pipe NPN7 is connected with outside reference voltage, and the emitter of the emitter of NPN pipe NPN7, NPN pipe NPN8, the collector electrode that NPN manages NPN6 are connected; The collector electrode of NPN pipe NPN7 is connected to the collector electrode of PNP pipe PNP5; The base stage of the base stage of PNP pipe PNP5, the collector electrode of PNP5, PNP pipe PNP6 is connected, and the collector electrode of PNP pipe PNP6 is connected to the collector electrode of NPN pipe NPN8, and resistance R 4 is connected between the base stage of base stage and NPN pipe NPN8 of NPN pipe NPN7.
As the 3rd preferred version; The described time is provided with the unit and comprises resistance and an electric capacity; One end of said resistance and an end of said electric capacity are connected the input of unit were set as the described time, and the other end of said resistance is connected with the other end of said electric capacity and lotus root is connected to ground.
Beneficial effect of the present invention: gain adjusting circuit of the present invention has adopted the level comparator unit, can farthest satisfy the amplification of less input signal, the big input signal gain of decay in good time; The linearity of this circuit is good, can not introduce extra nonlinear distortion to audio signal, has guaranteed the entire system performance.Gain adjusting circuit controllability of the present invention is strong, can change initial control level through the reference voltage that adjustment is provided with in advance, and the parameter change that the adjustment time is provided with the unit starts to control the time, can be used in various occasion according to actual needs.
Description of drawings
Fig. 1 is a gain automatic regulating circuit structural representation of the present invention.
Fig. 2 is the sketch map of the audio system of employing gain automatic regulating circuit of the present invention.
Fig. 3 is provided with the cellular construction sketch map for the level comparator unit and the time of the embodiment of the invention.
Fig. 4 is the gain-attenuation control circuitry structural representation of embodiments of the invention.
Fig. 5 is the gain reduction oscillogram of gain automatic regulating circuit of the present invention to Powerout.
Embodiment
Below in conjunction with accompanying drawing and concrete embodiment the present invention is done further elaboration.
Gain automatic regulating circuit of the present invention is as shown in Figure 1; Specifically comprise: level comparator unit and gain reduction unit; The reference voltage V t that two inputs of described level comparator unit are imported the output signal Poweramp of audio system respectively and are provided with in advance, the level comparator unit compares control signal Ctr of output to the gain reduction unit to two signals of input; The amplitude that the gain reduction unit judges whether to carry out gain reduction and decay gain according to the control signal of input, gain reduction unit output is as the output of said gain automatic regulating circuit.
The gain automatic regulating circuit here also comprises: the time is provided with the unit, and the time is provided with the unit and is used for setting and starts to control the time, and its input is used to import the control signal of described level comparator unit output.The time of starting to control is meant to from the output signal of audio system during greater than the reference voltage V t that is provided with in advance, to the time that gain automatic regulating circuit begins to carry out gain reduction, and the speed of gain automatic regulating circuit that started to control time response to big input signal reaction.
Fig. 2 has provided the sketch map of the audio system that adopts gain automatic regulating circuit of the present invention, comprising: preamplifier Preamp, power amplifier Poweramp, gain automatic regulating circuit also comprise the RC network of compensation.With reference to Fig. 2, input audio signal gets into Poweramp again and carries out power amplification through after the preparatory amplification of Preamp, and the power amplification output that obtains at last drives loud speaker.The output of gain automatic regulating circuit monitoring Poweramp, and with its with the Vt level ratio of setting, export a conditioning signal to the Preamp input; Input signal to Preamp is regulated, and realizes the gain reduction function, is specially: when output signal during greater than the reference voltage V t that is provided with in advance; Through starting to control the time; Voice signal to input Preamp is shunted according to control signal Ctr magnitude of voltage, the gain of attenuation factor, the distortion of prevention large-signal.When output level was no more than Vt, gain automatic regulating circuit was inoperative, fully guaranteed the gain than small-signal.
As stated, therefore the system configuration according to the Preamp in the audio system of the embodiment of the invention and Poweramp can adopt those skilled in the art to use always does not elaborate.Below the gain adjusting circuit of the audio system of the embodiment of the invention is described in detail.
The level comparator unit is as shown in Figure 3, and Fig. 3 has also provided the version that a kind of time is provided with the unit simultaneously, specifically comprises capacitor C t and resistance R t.
The level comparator unit is exported signal with Poweramp and is compared with the reference voltage V t that is provided with in advance, exports a control signal Ctr in view of the above.The reference voltage V t that is provided with in advance is as required through external setting-up, and when control Poweramp output signal need decay if reaching.The level comparator unit at first judges whether to carry out gain reduction, according to the output that detects Poweramp, through the gain reduction unit of control signal Ctr control chart 1.When system amplified than small-signal, the output of Poweramp was lower than the reference voltage V t that is provided with in advance, is amplified fully for making it, and control signal Ctr is low, did not work in the gain reduction unit; When system amplifies than large-signal; The output of Poweramp can be higher than Vt; Need carry out gain-adjusted, this moment, the electric current through NPN10 increased, and PNP9 is provided with the capacitor C t charging of unit to the time; Control signal Ctr is increased to about the starting resistor 1.4V (two base-emitter voltages of NPN1, NPN3) of gain reduction unit; Begin to carry out gain reduction, the amplitude of decay gain depends on the size of the control signal Ctr of level comparator unit output, and its amplitude is proportional to the output signal of Poweramp.
Fig. 4 has provided a kind of gain reduction cellular construction sketch map, can know from the operation principle of level comparator unit, when amplifying than small-signal, does not need the attenuation factor gain, and control signal Ctr is low, not conducting of NPN1 this moment, and do not work in the gain reduction unit.Do not receive the influence of gain-adjusted this moment fully than the amplification of small-signal.When amplifying than large-signal, control signal Ctr raises, and starts working in the gain reduction unit, shunt this moment the input of Preamp anode than the large-signal electric current, reduce the signal magnitude of the actual Preamp of being input to amplifier, realize the function of gain reduction.The amplitude of gain reduction depends on the magnitude of voltage of Ctr, and promptly the Ctr magnitude of voltage is big, and is big to Preamp anode input signal shunting action; The Ctr magnitude of voltage reduces, and shunting action weakens.
The concrete course of work is following: when control signal Ctr is increased to the 1.4V left and right sides, and the NPN1 conducting, the electric current of NPN2 mirror image NPN1, mirror image pipe PNP1 and PNP2 and mirror image pipe PNP4, PNP5 and PNP6 start working, and its current value and NPN2 pipe branch road are onesize; PNP4 pipe and PNP7 pipe constitute dynamic base current and eliminate circuit, and NPN9 and PNP3 setover as it, and purpose is to reduce the base current of difference input to pipe, to improve equivalent input impedance; NPN7 and NPN8 constitute differential pair tube, and the NPN6 that has setovered is as its tail current source, and size of current is It, and resistance R 4 is connected across differential pair tube NPN7 and NPN8 base stage input two ends simultaneously.Vref inserts a reference voltage; Can be regarded as exchanging ground; The output Adt of gain automatic regulating circuit is connected on the positive input of audio system preamplifier Preamp, and the equivalent output resistance between two base stage Vref of differential pair tube and the Adt is shunted Preamp anode input signal.
Equivalent output resistance between two base stage Vref of differential pair tube and the Adt is the parallel resistance of 1/gm and R4, and gm is the mutual conductance of differential pair tube NPN7, NPN8.When current source It was 0,1/gm was infinitely great, and equivalent output resistance is a resistance R 4; When current source It increased, it is big that gm becomes, and 1/gm diminishes, and then whole equivalent output resistance diminishes.Because the value of R4 is much larger than 1/gm, therefore to can be considered resistance be that resistance R 4 and resistance are two sections linear resistances of 1/gm to equivalent output resistance.
When gain-attenuation control circuitry was in running order, equivalent output resistance was 1/gm, and by gm=qIt/2kT, wherein, q is an electronic charge, and k is a Boltzmann constant, and T is the room temperature that absolute temperature is represented, can get this moment equivalent output resistance and current source It and be inversely proportional to.Control signal Ctrl and Powerout signal equivalence change in the same way, because the diode of NPN1 and NPN3 is connected, its Vbe voltage is approximate constant, therefore, and I
NPN1=(V
Ctrl-2V
Be)/(R1+2R3), wherein, V
CtrlBe control signal Ctr voltage, V
BeBase stage-emitter voltage for NPN pipe NPN1, NPN3.The electric current of NPN6 pipe comes through NPN1 pipe mirror image, and both equate, so the linear direct ratio of Ctrl magnitude of voltage and NPN6 current I t; Because the linear inverse relation of equivalent output resistance and It can get the linear inverse ratio of equivalent output resistance and Powerout signal, this linear inverse relation has greatly promoted the system linearity degree again; Therefore when Powerout increases; The Ctrl magnitude of voltage is linear to be increased, and the electric current direct ratio of NPN6 pipe increases, and variable resistor and It current value are inverse ratio and reduce linearly between Vref and the Adt; The audio signal of shunting Preamp positive input makes that this moment, Amplifier Gain reduced.
The time of starting to control is meant from the output signal of audio system during greater than the reference voltage that is provided with in advance, the time that begins to carry out gain reduction to gain automatic regulating circuit.The speed of gain automatic regulating circuit that started to control time response to big input signal reaction.If this time too weak point can cause the voice output level not clear, both poor sound quality; If oversize, can cause that system has little time action in signal input a period of time, sound occurs saturated and distortion.Time is provided with the unit and promptly is used for setting and starts to control the time, and this structure influence control signal Ctr rises to the required time of high level from low level, and its RC time constant is big more, and the time of starting to control is long more, and vice versa.Through this structure, can be provided with and start to control the time according to actual needs.
Be illustrated in figure 5 as at supply voltage 3V, 25 ℃ of following systems are to the gain reduction oscillogram of Powerout.Wherein, Preamp
IN is the original audio signal that is input to audio system.Can see, the Powerout signal amplitude hour, the Ctrl signal is low, gain-adjusted is not worked; When the Powerout signal increases gradually, when being higher than the Vt of setting, the Ctrl magnitude of voltage raises gradually, and gain reduction strengthens gradually.On scheming, can find out that this circuit has prevented the distortion of waveform, coincide with design result.
Those of ordinary skill in the art will appreciate that embodiment described here is in order to help reader understanding's principle of the present invention, should to be understood that protection scope of the present invention is not limited to such special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combinations that do not break away from essence of the present invention according to these teachings disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.
Claims (5)
1. gain automatic regulating circuit that is used for audio system; Specifically comprise: level comparator unit and gain reduction unit; The reference voltage that two inputs of described level comparator unit are imported the output signal of audio system respectively and are provided with in advance, the level comparator unit compares one of output to two signals importing and controls signal to the gain reduction unit; The amplitude that the gain reduction unit judges whether to carry out gain reduction and decay gain according to the control signal of input, gain reduction unit output is as the output of said gain automatic regulating circuit.
2. the gain automatic regulating circuit that is used for audio system according to claim 1; It is characterized in that; Said gain automatic regulating circuit also comprises: the time is provided with the unit, and the described time is provided with the unit and is used for setting and starts to control the time, saidly starts to control the time for from the output signal of audio system during greater than the reference voltage that is provided with in advance; To the time that gain automatic regulating circuit begins to carry out gain reduction, its input is used to import the control signal of described level comparator unit output.
3. the gain automatic regulating circuit that is used for audio system according to claim 1 and 2 is characterized in that, described level comparator unit comprises: NPN pipe NPN9, NPN10, NPN11, PNP pipe PNP8, PNP9;
Concrete annexation is: the base stage of NPN pipe NPN10 is used for input as the first input end of described level comparator unit and treats conditioning signal; The emitter of the collector electrode of NPN10, the emitter of PNP8 and PNP pipe PNP9 is connected to outside supply voltage; The emitter of the emitter of NPN pipe NPN10, NPN pipe NPN11 is connected with the collector electrode of NPN pipe NPN9; The base stage of NPN pipe NPN11 is used to import the reference voltage that is provided with in advance as second input of described level comparator unit; The collector electrode of NPN pipe NPN11 is connected to the collector electrode of PNP pipe PNP8; The base stage of NPN pipe NPN9 is connected to outside bias voltage; The emitter of NPN pipe NPN9 is connected to ground, and the base stage of PNP pipe PNP8, collector electrode are connected with the base stage of PNP pipe PNP9, and the collector electrode of PNP pipe PNP9 is as the output of described level comparator unit.
4. the gain automatic regulating circuit that is used for audio system according to claim 3; It is characterized in that; Described gain reduction unit; Comprise: NPN pipe NPN1, NPN2, NPN3, NPN4, NPN5, NPN6, NPN7, NPN8, NPN9, PNP pipe PNP1, PNP2, PNP3, PNP4, PNP5, PNP6, PNP7, and resistance R 1, R2, R3, R4;
Concrete annexation is: an end of resistance R 1 is as the input of described gain reduction unit, and the other end of resistance R 1 is connected with the collector electrode of NPN pipe NPN1, the base stage of NPN1, the base stage of NPN2; The emitter of NPN pipe NPN1 is connected to the collector electrode of NPN pipe NPN3; The emitter of NPN pipe NPN2 is connected to the collector electrode of NPN pipe NPN3; Resistance R 2 is connected between NPN pipe NPN2 collector electrode and the PNP pipe PNP1 collector electrode; Base stage and the collector electrode short circuit of NPN pipe NPN3; Resistance R 3 is connected between the emitter and ground of NPN pipe NPN3; The base stage of the base stage of PNP pipe PNP1, the collector electrode of PNP1, PNP pipe PNP2 is connected; The emitter of the collector electrode of the emitter of PNP pipe PNP1, the emitter of PNP2, NPN pipe NPN9, the emitter of PNP pipe PNP4, PNP pipe PNP7, the emitter of PNP pipe PNP5 are connected to outside supply voltage, and the collector electrode of PNP pipe PNP2 is connected to the collector electrode of NPN pipe NPN4, and the base stage of the base stage of NPN pipe NPN4, the collector electrode of NPN4, NPN pipe NPN5 is connected with the base stage of NPN pipe NPN6; The collector electrode that the emitter of the emitter of NPN pipe NPN4, NPN pipe NPN5 all is connected to ground, NPN pipe NPN5 is connected to the emitter of NPN pipe NPN9; The base stage of NPN pipe NPN9 is connected to the collector electrode of PNP pipe PNP3, and the base stage of the base stage of PNP pipe PNP3, the collector electrode of PNP3, PNP pipe PNP4 is connected, and the collector electrode of PNP pipe PNP4 is connected to the base stage of NPN pipe NPN7; The base stage of PNP pipe PNP7 is connected to the base stage of PNP pipe PNP3; The collector electrode of the base stage of NPN pipe NPN8, the collector electrode of NPN8 and PNP pipe PNP7 is connected and as the output of described gain reduction unit, the base stage of NPN pipe NPN7 is connected with outside reference voltage, and the emitter of the emitter of NPN pipe NPN7, NPN pipe NPN8, the collector electrode that NPN manages NPN6 are connected; The collector electrode of NPN pipe NPN7 is connected to the collector electrode of PNP pipe PNP5; The base stage of the base stage of PNP pipe PNP5, the collector electrode of PNP5, PNP pipe PNP6 is connected, and the collector electrode of PNP pipe PNP6 is connected to the collector electrode of NPN pipe NPN8, and resistance R 4 is connected between the base stage of base stage and NPN pipe NPN8 of NPN pipe NPN7.
5. according to claim 3 or the 4 described automatic gain adjusting circuits that are used for audio system; It is characterized in that; The described time is provided with the unit and comprises resistance and an electric capacity; One end of said resistance and an end of said electric capacity are connected the input of unit were set as the described time, and the other end of said resistance is connected with the other end of said electric capacity and lotus root is connected to ground.
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| CN201210335203.7A CN102801396B (en) | 2012-09-12 | 2012-09-12 | Automatic gain adjustment circuit in audio system |
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| CN201210335203.7A CN102801396B (en) | 2012-09-12 | 2012-09-12 | Automatic gain adjustment circuit in audio system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111327937A (en) * | 2020-04-08 | 2020-06-23 | 崔建国 | Intelligent small audio signal compressor based on feedforward control and implementation method |
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| US4264873A (en) * | 1978-07-19 | 1981-04-28 | Hitachi, Ltd. | Differential amplification circuit |
| JPH0989944A (en) * | 1995-09-28 | 1997-04-04 | Yokogawa Electric Corp | Wind comparator |
| CN1179241A (en) * | 1995-03-23 | 1998-04-15 | Rca汤姆森许可公司 | Dual action automatic sound level control |
| CN101114819A (en) * | 2007-08-21 | 2008-01-30 | 深圳华为通信技术有限公司 | Sound volume controller |
| CN102201792A (en) * | 2010-03-25 | 2011-09-28 | 上海沙丘微电子有限公司 | Automatic gain control circuit of audio power amplifier |
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2012
- 2012-09-12 CN CN201210335203.7A patent/CN102801396B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4264873A (en) * | 1978-07-19 | 1981-04-28 | Hitachi, Ltd. | Differential amplification circuit |
| CN1179241A (en) * | 1995-03-23 | 1998-04-15 | Rca汤姆森许可公司 | Dual action automatic sound level control |
| JPH0989944A (en) * | 1995-09-28 | 1997-04-04 | Yokogawa Electric Corp | Wind comparator |
| CN101114819A (en) * | 2007-08-21 | 2008-01-30 | 深圳华为通信技术有限公司 | Sound volume controller |
| CN102201792A (en) * | 2010-03-25 | 2011-09-28 | 上海沙丘微电子有限公司 | Automatic gain control circuit of audio power amplifier |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111327937A (en) * | 2020-04-08 | 2020-06-23 | 崔建国 | Intelligent small audio signal compressor based on feedforward control and implementation method |
| CN111327937B (en) * | 2020-04-08 | 2023-08-01 | 山西工程技术学院 | Intelligent small-sized audio signal compressor based on feedforward control and implementation method |
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| CN102801396B (en) | 2014-10-15 |
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