CN203167244U - Audio processing circuit and earphone - Google Patents
Audio processing circuit and earphone Download PDFInfo
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- CN203167244U CN203167244U CN 201320071677 CN201320071677U CN203167244U CN 203167244 U CN203167244 U CN 203167244U CN 201320071677 CN201320071677 CN 201320071677 CN 201320071677 U CN201320071677 U CN 201320071677U CN 203167244 U CN203167244 U CN 203167244U
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Abstract
The utility model discloses an audio processing circuit which comprises a playback circuit, a pickup circuit and a third resistor, wherein the third resistor is connected between a common end of an audio interface and a ground terminal of an audio processing circuit; the playback circuit comprises a difference input circuit, a playback signal processing circuit and playback equipment, and the pickup circuit comprises pickup equipment, a pickup signal processing circuit and an inverse-phase proportion summation circuit. Correspondingly, the utility model further discloses the earphone which comprises the audio processing circuit. The audio processing circuit and the earphone can effectively reduce the noise caused by interference of a charging current on the pickup circuit and the playback circuit, and can eliminate the terrestrial current noise caused by multipath common ground of the earphone and audio equipment.
Description
Technical field
The utility model relates to the audio signal processing technique field, particularly a kind of audio frequency processing circuit and earphone.
Background technology
At present, the application of earphone is more and more general.A lot of wireless headsets not only can use under wireless condition, and have simultaneously line jack is arranged.This earphone both can come playback of audio information by wireless mode, can be connected with the audio frequency apparatus that has output function (as PC etc.) by line jack is arranged again, adopted wired mode playback of audio information.
Earphone generally all adopts the rechargeable battery power supply, under the situation of the low electricity of battery, need charge to battery, can also carry out pickup by earphone Mike in the audio plays limit while charging.When same audio frequency apparatus of earphone connection carries out audio frequency broadcast, pickup and charging, under normal condition, charging current in the earphone is back in the audio frequency apparatus by the ground wire (PGND) of its charging circuit, audio signal is back in the audio frequency apparatus by the ground wire (AGND) of its audio frequency processing circuit, does not disturb mutually.But, because the reference potential of charging circuit is that the reference potential of PGND and audio frequency processing circuit is that AGND is equipotentiality in the earphone, the charging current that changes will some be back to the audio frequency apparatus the inside by AGND, like this, the charging current that changes will have influence on the output voltage of audio frequency processing circuit, in the audio frequency of playing and the audio frequency that picks up, will produce drone current noise, have a strong impact on picking up and result of broadcast of audio frequency.
For example; situation shown in Figure 1; the audio input end of earphone is connected to the audio output interface of a computer; its charging inlet connects on the charging inlet (as USB interface) of this computer simultaneously, and earphone is play the audio frequency of this computer and charged by this computer, in this case; will there be lasting drone noise in the audio frequency of playing in the earphone; and drone noise will increase along with the increase of volume, suspend or play when switching playing, and this noise is all the more obvious.
The utility model content
A kind of audio frequency processing circuit and earphone that the utility model provides are to solve existing earphone by connect same audio frequency apparatus and carry out simultaneously that audio frequency is play, audio frequency picks up and exist when charging the problem of noise in the audio frequency of being play and the audio frequency that picks up.
The utility model provides a kind of audio frequency processing circuit, described audio frequency processing circuit comprises audio interface, playback circuit, pickup circuit, described audio frequency processing circuit also comprises the 3rd resistance, described the 3rd resistance is connected between the common port and audio frequency processing circuit earth terminal of described audio interface, and the resistance of described the 3rd resistance is far longer than the equivalent resistance of audio signal wire;
Described playback circuit comprises difference input circuit, playback signal processing circuit and tone playing equipment, described audio interface will be sent into described difference input circuit from the audio signal of audio frequency apparatus and carry out difference input processing, enter described playback signal processing circuit again and carry out the processing of playback signal, at last by described tone playing equipment output;
Described pickup circuit comprises pick up facility, pickup signal treatment circuit and anti-phase ratio summing circuit, described pick up facility picks up audio signal and is sent to described pickup signal treatment circuit, after described audio signal was carried out the pickup signal processing via the pickup signal treatment circuit, oppositely being sued for peace by described anti-phase ratio summing circuit, processing is back sent into audio frequency apparatus by described audio interface again.
In such scheme, the resistance of described the 3rd resistance at 100 Ω between the 100K Ω.
In such scheme, described difference input circuit comprises at least four resistance and an audio frequency amplifier, wherein, two resistance string in described four resistance are associated in the first input end of described audio frequency amplifier, a resistance string is associated in second input of described audio frequency amplifier, and another resistance is attempted by between second input and output of described audio frequency amplifier.
In such scheme, described difference input circuit also comprises at least three electric capacity, is connected on first input end, second input and the output of described audio frequency amplifier.
In such scheme, it is characterized in that described playback circuit is at least one.
In such scheme, described anti-phase ratio summing circuit comprises at least four resistance and an audio frequency amplifier, wherein, two resistance string in described four resistance are associated in the first input end of described audio frequency amplifier, a resistance string is associated in second input of described audio frequency amplifier, and another resistance is attempted by between second input and output of described audio frequency amplifier.
In such scheme, described anti-phase ratio summing circuit also comprises at least three electric capacity, is connected on first input end, second input and the output of described audio frequency amplifier.
In such scheme, described pickup circuit also comprises: voltage-stabilizing output circuit is connected with described anti-phase ratio summing circuit, for described anti-phase ratio summing circuit provides bias voltage.
In such scheme, described voltage-stabilizing output circuit comprises electric capacity, diode, two resistance and operational amplifier, connect described electric capacity, a described resistance and described diode on the first input end of described operational amplifier respectively, described electric capacity is connected the audio frequency processing circuit earth terminal respectively with described diode, a described resistance connects power supply, short circuit between second input of described operational amplifier and the input, output connects another described resistance, and another described resistance connects the first input end of described operational amplifier.
The utility model also provides a kind of earphone, and described earphone comprises charging circuit, battery and above-mentioned audio frequency processing circuit; Described charging circuit connects charging inlet and the described battery of audio frequency apparatus, is described battery; Described battery is used to described audio frequency processing circuit power supply.
The beneficial effect of the utility model embodiment is: be serially connected with the 3rd resistance between the common port of described audio interface and the audio frequency processing circuit earth terminal, make that common port and the audio frequency processing circuit earth terminal of audio interface are separated, avoid charging current to flow in the audio interface; Simultaneously, in playback circuit, also set up the difference input circuit, eliminated the interference of charging current to playback circuit sound intermediate frequency signal, common-mode signal is different between the earth terminal of offsetting audio frequency apparatus simultaneously and the earth terminal of this earphone, eliminate the earth terminal electrical potential difference to the influence of audio signal, reach the purpose of eliminating noise in institute's audio plays; And, in described pickup circuit, set up anti-phase ratio summing circuit, eliminated the interference of charging current to pickup circuit sound intermediate frequency signal.
In addition, in described pickup circuit, also increased voltage-stabilizing output circuit, can adopt the power supply of single supply system at earphone is to provide bias voltage for described anti-phase ratio summing circuit, increase the stability of anti-phase ratio summing circuit upper offset voltage, improve anti-phase ratio summing circuit to the consumption of noise.
The audio frequency processing circuit that the utility model embodiment provides and earphone, its circuit can effectively be subdued charging current pickup circuit and playback circuit are disturbed the noise that causes, and also can eliminate earphone and audio frequency apparatus because the earth-current noise that multipath causes altogether.
Description of drawings
Fig. 1 is the connection diagram of earphone and audio frequency apparatus in the prior art;
Fig. 2 is the composition structural representation of a kind of audio frequency processing circuit among the utility model embodiment;
Fig. 3 is the circuit diagram of a kind of preferred embodiment of the utility model embodiment sound intermediate frequency treatment circuit;
Fig. 4 charges and the circuit diagram of audio signal transmission for earphone among the utility model embodiment and by same audio frequency apparatus.
Embodiment
For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing the utility model execution mode is described in further detail.
Basic thought of the present utility model is, the earphone that a kind of audio frequency processing circuit is provided and comprises this audio frequency processing circuit, described audio frequency processing circuit comprises the 3rd resistance, playback circuit and pickup circuit, wherein, be serially connected with the 3rd resistance between the earth terminal of described audio frequency processing circuit and the audio interface common port, in playback circuit, also set up simultaneously the difference input circuit, make that the earth terminal of the earth terminal of playback circuit and charging circuit is separated by this resistance, avoid charging current to flow in the playback circuit, eliminated the interference of charging current to playback circuit sound intermediate frequency signal, common-mode signal is different between the earth terminal of offsetting audio frequency apparatus simultaneously and the earth terminal of this earphone, eliminate the earth terminal electrical potential difference to the influence of audio signal, reach the purpose of eliminating noise in institute's audio plays; In addition, also in described pickup circuit, set up anti-phase ratio summing circuit, made that the audio signal in the pickup circuit can be not disturbed, eliminated the noise of pickup circuit sound intermediate frequency signal.
Embodiment one
As shown in Figure 2, the audio frequency processing circuit that provides of the utility model embodiment mainly can comprise: the 3rd resistance R 3, playback circuit 11, pickup circuit 12 and be used for the audio interface 13 of external audio frequency equipment; Wherein, described the 3rd resistance R 3 is connected between the public terminal GND 2 and audio frequency processing circuit earth terminal GND of described audio interface 13, and its resistance is far longer than the equivalent resistance of holding wire in the audio frequency processing circuit.
Playback circuit 11 comprises difference input circuit 112, playback signal processing circuit 113 and tone playing equipment 114, described audio interface 13 will be sent into difference input circuit 112 from the audio signal of audio frequency apparatus and carry out difference input processing, enter playback signal processing circuit 113 again and carry out the processing of playback signal, at last by tone playing equipment 114 outputs;
Pickup circuit 12 comprises pick up facility 121, pickup signal treatment circuit 122 and anti-phase ratio summing circuit 123, pick up facility 121 picks up audio signal and is sent to described pickup signal treatment circuit 122, after described audio signal was carried out the pickup signal processing via pickup signal treatment circuit 122, oppositely being sued for peace by anti-phase ratio summing circuit 123, processing is back sent into audio frequency apparatus by described audio interface 13 again.
Concrete, described audio interface 13 comprises for the pickup interface 131 of external audio frequency equipment audio input interface, common port 132 and is used for the playback interface 133 of external audio frequency equipment audio output interface;
The first input end of described difference input circuit 112 connects described playback interface 133, second input connects described common port 132, output connects the input of described playback signal processing circuit As, and the output of described playback signal processing circuit 113 connects described tone playing equipment 114;
The output of described pick up facility 121 connects the input of described pickup signal treatment circuit 122, the output of described pickup signal treatment circuit 122 connects second input of described anti-phase ratio summing circuit 121, the first input end of described anti-phase ratio summing circuit 121 connects described common port 132, and output connects described pickup interface 131.
Pick up facility described in the utility model embodiment is for being used for picking up the equipment of audio signal, as microphone etc.; Tone playing equipment is for being used for the equipment of output audio signal, as loud speaker etc.
If adopt the single supply system to power, then also need to increase the circuit be used to bias voltage is provided in the above-mentioned audio frequency processing circuit, therefore, pickup circuit 12 can also comprise: voltage-stabilizing output circuit 124, and for anti-phase ratio summing circuit 123 provides stable bias voltage.Concrete, the output of voltage-stabilizing output circuit 124 connects the first input end of described anti-phase ratio summing circuit 123, and first input end connects power supply.
Embodiment two
As shown in Figure 3, be the circuit diagram of the utility model embodiment sound intermediate frequency treatment circuit.Wherein, audio frequency processing circuit comprises the 3rd resistance R 3, audio interface, L channel playback circuit, R channel playback circuit and pickup circuit.
Wherein, R3 is connected between the public terminal GND 2 and audio frequency processing circuit earth terminal GND of described audio interface, and its resistance is far longer than the equivalent resistance of holding wire in the audio frequency processing circuit.
The L channel playback circuit comprises the first difference input circuit, the first playback signal processing circuit As1 and the first loud speaker L, is used for the left channel audio signal from audio frequency apparatus is carried out playback.The first difference input circuit comprises the 4th resistance R 4, the 5th resistance R 5, the 6th resistance R 6, the 16 resistance R 16 and an audio frequency amplifier A1, R4 is connected on the first input end of A1 and connects the 3rd interface 3, R16 is connected on the first input end of A1 and connects audio frequency processing circuit earth terminal GND, R5 is connected on second input of A1 and connects GND2, and R6 is attempted by between second input and output of A1.The input of the first playback signal processing circuit As1 connects the output of A1, and output connects the first input end of first loud speaker.Second input of first loud speaker connects audio frequency processing circuit earth terminal GND.In addition, the first difference input circuit can also comprise first capacitor C 1, second capacitor C 2 and the 5th capacitor C 5, and C1 connects with R4, is connected the first input end of A1; C2 connects with R5, is connected second input of A1; C5 is connected between A1 output and the As1 input.
The R channel playback circuit comprises the second difference input circuit, the second playback signal processing circuit As2 and the second loud speaker R, is used for the right channel audio signal from audio frequency apparatus is carried out playback.The second difference input circuit comprises the 7th resistance R 7, the 8th resistance R 8, the 9th resistance R 9, the 17 resistance R 17 and an audio frequency amplifier A2, R8 is connected on the first input end of A2 and connects the 4th interface 4, R17 is connected on the first input end of A2 and connects audio frequency processing circuit earth terminal GND, R7 is connected on second input of A2 and connects GND2, and R9 is attempted by between second input and output of A2.The input of the second playback signal processing circuit As2 connects the output of A2, and output connects the first input end of second loud speaker.Second input of second loud speaker connects GND.In addition, the second difference input circuit can also comprise the 3rd capacitor C 3, the 4th capacitor C 4 and the 6th capacitor C 6, and C3 connects with R7, is connected the first input end of A2; C4 connects with R8, is connected second input of A2; C6 is connected between A2 output and the As2 input.
The pickup circuit comprises microphone 331, pickup signal treatment circuit Am, anti-phase ratio summing circuit and voltage-stabilizing output circuit, wherein, anti-phase ratio summing circuit comprises the tenth resistance R 10, the 11 resistance R 11, second resistance R 12 and audio frequency amplifier A5, R10 is attempted by between second input and output of A5, R11 is connected on second input of A5 and connects the output of Am, and R12 is connected on the first input end of A5 and connects GND2.Voltage-stabilizing output circuit comprises the 9th capacitor C 9, diode D1, the 14 resistance R 14, the 13 resistance R 13 and operational amplifier A 4, the first input end of A4 connects C9, R14 and D1, C9 is connected GND respectively with D1, R14 connects power Vcc, short circuit between second input of A4 and the input, the output of A4 connects R13, and R13 connects the first input end of A5.In addition, anti-phase ratio summing circuit can also comprise the 7th capacitor C 7, the 8th capacitor C 8 and/or the tenth capacitor C 10, and C7 is connected on the output of A5, and C7 connects with R12, and C8 connects with R11, is used for the flip-flop on the reduction circuit.
Here, the resistance of R3 need be far longer than the resistance of the equivalent resistance of the equivalent resistance of charging circuit holding wire and audio frequency processing circuit holding wire.In general, the resistance of the equivalent resistance of the equivalent resistance of charging circuit holding wire and audio frequency processing circuit holding wire is about several milliohms, and therefore, between the 100K Ω, for example, R3 can be 100 Ω to the resistance of preferred R3 at 100 Ω.Like this, R3 can keep apart GND2 and GND, avoids the charging current in the charging circuit to flow in the playback circuit, can effectively subdue the noise that charging current interference tones signal causes.
Wherein, C1, C2, C3, C4, C5, C6, C9, C10 are the input coupling capacitance, and capacitance is preferably 10 μ F, is used for the flip-flop on the erasure signal line.The capacitance of C7, C8 is preferably 1 μ F.
Here, the resistance value of R4, R5, R6, R7, R8, R9, R10, R11, R12 is preferably 4.7K Ω, and the resistance value of R13 is preferably 200K Ω, and the resistance value of R14 is preferably 1M Ω.
Among the utility model embodiment, form subtraction circuit by R4, R5, R6 and A1, gain is 1; Form subtraction circuit by R7, R8, R9 and A2, gain is 1.Here, according to the practical application needs, can adjust the gain of the first difference input circuit by the resistance value of adjusting R4, R5, R6, can adjust the gain of the second difference input circuit by the resistance value of adjusting R7, R8, R9.The first audio frequency amplifier A1 and the second audio frequency amplifier A2 mainly play the function that differential signal changes single-ended signal, except also having amplifying signal in addition, improving effects such as input impedance, reinforcing band load capacity.
Need to prove that in the above-mentioned audio frequency processing circuit, A1, As1, L, A2, As2, R, Am, A5 are reference potential with the voltage of GND all.A5, As1, A2, Am can also connect power Vcc.
Among the utility model embodiment, receiving after the series resistance on the GND2 on the GND, to separate by resistance between GND2 and the GND, and the reference potential of charging circuit is the current potential of GND in the earphone, like this, the variable quantity of charging current just can not flow in the audio interface, has reduced the influence of charging current to audio signal, has subdued the noise that the variation of charging current causes playback circuit sound intermediate frequency signal; Simultaneously, in the playback circuit, also added the difference input circuit, mode by the difference input is carried out subtraction process to the audio signal in the playback circuit, common-mode signal is different between the earth terminal of offsetting audio frequency apparatus and the voicefrequency circuit earth terminal, has eliminated between the earth terminal of audio frequency apparatus and the voicefrequency circuit earth terminal electrical potential difference to the influence of audio signal.
Among the utility model embodiment, in the pickup circuit, increased anti-phase ratio summing circuit, by this anti-phase ratio summing circuit noise is added on the microphone output line of pickup circuit, make that the audio signal in the pickup circuit can be not disturbed, eliminated the noise of pickup circuit sound intermediate frequency signal.In addition, also increased voltage-stabilizing output circuit, can adopt the power supply of single supply system at earphone is to provide bias voltage for anti-phase ratio summing circuit, increase the stability of anti-phase ratio summing circuit upper offset voltage, bias voltage is more stable, and anti-phase ratio summing circuit is just more good to the consumption of noise.
Need to prove, those skilled in the art can directly obtain based on foregoing description, adopt a plurality of sound channels if desired, so a plurality of playback circuits can be set in audio frequency processing circuit accordingly, the corresponding sound channel of each playback circuit, include the tone playing equipment of a difference input circuit, a playback signal processing circuit and a similar loud speaker, the playback circuit described in its circuit structure and circuit connecting relation and the utility model embodiment is similar, does not repeat them here.
Embodiment three
The utility model embodiment provides a kind of earphone, and as shown in Figure 4, described earphone can comprise: charging circuit, battery 42 and audio frequency processing circuit, and wherein, charging circuit connects charging inlet and the described battery 42 of audio frequency apparatus, is battery 42 chargings; Audio frequency processing circuit connects audio output interface and the audio input interface of audio frequency apparatus, the audio signal of audio frequency apparatus is handled and is exported, and will pick up audio signal and handle after send audio frequency apparatus to; Battery 42 is used to the audio frequency processing circuit power supply.Wherein, described audio frequency processing circuit is identical with embodiment one or embodiment two described audio frequency processing circuits.
Entire headset is the zero potential benchmark with the current potential of audio frequency processing circuit earth terminal GND.
As shown in Figure 4, charging circuit comprises that the equivalent resistance on charging process module 411 and each holding wire of charging circuit (VBUS and PGND) is first resistance R 1.Wherein, the input of charging process module 411 connects the charging inlet of audio frequency apparatus by charge power supply line VBUS, output connects battery 42, the earth terminal of battery 42 connects the charging circuit earth terminal, by the earth terminal GND1 of charging ground wire PGND connection audio frequency apparatus, charging circuit earth terminal and audio frequency processing circuit earth terminal GND are idiostatic.Wherein, charging process module 411 specifically can be a kind of chip for charging process, for example can be that Texas Instrument's model is the chip of BQ24040.
Audio frequency processing circuit comprises pickup circuit, playback circuit, the 3rd resistance R 3, the pickup circuit comprises microphone 421, pickup signal treatment circuit Am and anti-phase ratio summing circuit 422, by the audio input interface on the pickup signal line MIC connection audio frequency apparatus, playback circuit comprises difference input circuit 431, pickup signal treatment circuit As and loud speaker 432, by the audio output interface on the playback holding wire L/R connection audio frequency apparatus, the earth terminal GND2 of audio frequency processing circuit connects GND1 by audio frequency ground wire COM.Wherein, the equivalent resistance on each holding wire (pickup signal line MIC, playback holding wire L/R and audio frequency ground wire COM) is second resistance R 2.
Wherein, the particular circuit configurations of described audio frequency processing circuit is identical with embodiment one or embodiment two described audio frequency processing circuits.
Need to prove, also can comprise the charging curve management in the present embodiment in the charging circuit, flow through one or more circuit wherein such as pressing protection, level conversion, state indication, battery protecting circuit, power source path switching, other interlock circuits.
Two sound channels also can have a plurality of sound channels about playback circuit can have, specifically with reference to the description among the embodiment two.Except comprising audio frequency amplifier, can also comprise one or more circuit wherein such as signal input circuit, coder (CODEC), audio signal digit processing, noise reduction process, audio power amplification, the processing of volume sound effect control in the playback signal processing circuit in the playback circuit.
Pickup signal treatment circuit in the pickup circuit can also comprise one or more circuit wherein such as pick up facility (as microphone) driving, CODEC, audio signal digit processing, noise reduction process, the processing of volume sound effect control except comprising audio frequency amplifier.
On the audio frequency apparatus, the current potential on the charging inlet is U
p, the current potential on the GND1 is U
G1, then the voltage on the charging inlet is U
pWith U
G1Between difference U
CHG, suppose that this magnitude of voltage is 5V.
On the charging circuit, the charging current on the charging circuit power line VBUS is I
CHG=I
CC+ Δ i, wherein, I
CCBe the constant composition of charging current, Δ i is the variation composition of charging current, and Δ i is generally below mA.
Because R
3+ R
2＞＞R
1, according to Ohm's law, can obtain following formula (1).
Δi
1＝R
1/(R
1+R
2+R
3)*Δi≈0(1)
Wherein, Δ i
1Component for charging current variable quantity among the audio frequency ground wire COM.Δ i
1The proportion that accounts for Δ i is very little, can think: Δ i
1=0.Therefore, the noise source in audio frequency processing circuit is Δ U
G2=R
2* Δ i
1+ Δ U
G1=Δ U, wherein, Δ U=-Δ i * (R
1//R
2) be U on the GND1
G1Voltage variety.
For playback circuit, the voltage variety Δ U of first input end on the difference input circuit
1+=Δ I
L/R* R
2+ Δ U=Δ U, wherein, Δ I
L/RBe the current change quantity on the playback holding wire, its value is zero, and the voltage variety on second input is Δ U
1-=Δ U
G2=Δ U, the voltage variety Δ U on the playback signal processing circuit input
6=A
1* (Δ U
1+-Δ U
1-)=A
1* (Δ U-Δ U)=0, the variation delta U of tone playing equipment input voltage
SPK_H=A
S* Δ U
6=0, A
SYield value for the playback signal processing circuit.Therefore, among the utility model embodiment, send audio frequency apparatus here audio signal by the difference input circuit and subtract each other, eliminated the noise that charging current produces, finally eliminated the noise in the playback circuit sound intermediate frequency signal.
For the pickup circuit, the voltage U on anti-phase ratio summing circuit second input
2-=-A
M* U
MIC_H, the voltage U on second input
2+=U
G2=Δ U, like this, the voltage U of anti-phase ratio summing circuit output
3=U
2+-U
2-=Δ U+A
M* U
MIC_H, U
2+Be the voltage of anti-phase ratio summing circuit first input end, U
2-Be the voltage of anti-phase ratio summing circuit second input, A
MBe the yield value of pickup signal treatment circuit, U
MIC_HBe the input voltage of pick up facility, wherein, the input voltage U on the audio frequency apparatus audio input interface
MIC_A=U
M-U
G1=U
3-I
M* R
2-U
G1=Δ U+A
M* U
MIC_H-I
M* R
2-Δ U=A
M* U
MIC_H-I
M* R
2, wherein, U
MBe the voltage on the audio frequency apparatus audio input interface, I
MBe the circuit on the pickup signal line, therefore, can obtain the variation delta U of the input voltage on the audio frequency apparatus audio input interface
MIC_A=0, it is zero that the audio signal that the audio frequency apparatus termination is received is subjected to the influence of charging current, has eliminated the noise that charging current produces pickup circuit sound intermediate frequency signal.
Among the utility model embodiment, receiving after the series resistance on the GND2 on the GND, to separate by resistance between GND2 and the GND, and the reference potential of charging circuit is the current potential of GND in the earphone, like this, the variable quantity of charging current just can not flow in the audio interface, has reduced the influence of charging current to audio signal, has subdued the noise that the variation of charging current causes playback circuit sound intermediate frequency signal; Simultaneously, in the playback circuit, also added the difference input circuit, mode by the difference input is carried out subtraction process to the audio signal in the playback circuit, common-mode signal is different between the earth terminal of offsetting audio frequency apparatus and the voicefrequency circuit earth terminal, has eliminated between the earth terminal of audio frequency apparatus and the voicefrequency circuit earth terminal electrical potential difference to the influence of audio signal.
Among the utility model embodiment, in the pickup circuit, increased anti-phase ratio summing circuit, by this anti-phase ratio summing circuit the noise on the audio frequency apparatus earth terminal is added on the microphone output line of pickup circuit, make that the audio signal in the pickup circuit can be not disturbed, eliminated the noise of pickup circuit sound intermediate frequency signal.In addition, also increased voltage-stabilizing output circuit, can adopt the power supply of single supply system at earphone is to provide bias voltage for anti-phase ratio summing circuit, increase the stability of anti-phase ratio summing circuit upper offset voltage, bias voltage is more stable, and anti-phase ratio summing circuit is just more good to the consumption of noise.
Need to prove, those skilled in the art can directly obtain based on foregoing description, adopt a plurality of sound channels if desired, can comprise a plurality of playback electronic circuits so in the playback circuit, the corresponding sound channel of each playback electronic circuit, include the tone playing equipment of a difference input circuit, a playback signal processing circuit and a similar loud speaker, the playback electronic circuit described in its circuit structure and circuit connecting relation and the utility model embodiment is similar, does not repeat them here.
In summary, the earphone that the utility model embodiment provides, its circuit can effectively be subdued charging current pickup circuit and playback circuit are disturbed the noise that causes, and also can eliminate earphone and audio frequency apparatus because the earth-current noise that multipath causes altogether.
The above is preferred embodiment of the present utility model only, is not for limiting protection range of the present utility model.All any modifications of within spirit of the present utility model and principle, doing, be equal to replacement, improvement etc., all be included in the protection range of the present utility model.
Claims (10)
1. audio frequency processing circuit, described audio frequency processing circuit comprises audio interface, playback circuit, pickup circuit, it is characterized in that, described audio frequency processing circuit also comprises the 3rd resistance, described the 3rd resistance is connected between the common port and audio frequency processing circuit earth terminal of described audio interface, and the resistance of described the 3rd resistance is far longer than the equivalent resistance of audio signal wire;
Described playback circuit comprises difference input circuit, playback signal processing circuit and tone playing equipment, described audio interface will be sent into described difference input circuit from the audio signal of audio frequency apparatus and carry out difference input processing, enter described playback signal processing circuit again and carry out the processing of playback signal, at last by described tone playing equipment output;
Described pickup circuit comprises pick up facility, pickup signal treatment circuit and anti-phase ratio summing circuit, described pick up facility picks up audio signal and is sent to described pickup signal treatment circuit, after described audio signal was carried out the pickup signal processing via the pickup signal treatment circuit, oppositely being sued for peace by described anti-phase ratio summing circuit, processing is back sent into audio frequency apparatus by described audio interface again.
2. audio frequency processing circuit according to claim 1 is characterized in that, the resistance of described the 3rd resistance at 100 Ω between the 100K Ω.
3. audio frequency processing circuit according to claim 1, it is characterized in that, described difference input circuit comprises at least four resistance and an audio frequency amplifier, wherein, two resistance string in described four resistance are associated in the first input end of described audio frequency amplifier, a resistance string is associated in second input of described audio frequency amplifier, and another resistance is attempted by between second input and output of described audio frequency amplifier.
4. audio frequency processing circuit according to claim 3 is characterized in that, described difference input circuit also comprises at least three electric capacity, is connected on first input end, second input and the output of described audio frequency amplifier.
5. according to claim 1,3 or 4 described audio frequency processing circuits, it is characterized in that described playback circuit is at least one.
6. audio frequency processing circuit according to claim 1, it is characterized in that, described anti-phase ratio summing circuit comprises at least four resistance and an audio frequency amplifier, wherein, two resistance string in described four resistance are associated in the first input end of described audio frequency amplifier, a resistance string is associated in second input of described audio frequency amplifier, and another resistance is attempted by between second input and output of described audio frequency amplifier.
7. audio frequency processing circuit according to claim 6 is characterized in that, described anti-phase ratio summing circuit also comprises at least three electric capacity, is connected on first input end, second input and the output of described audio frequency amplifier.
8. according to claim 1,6 or 7 described audio frequency processing circuits, it is characterized in that described pickup circuit also comprises: voltage-stabilizing output circuit is connected with described anti-phase ratio summing circuit, for described anti-phase ratio summing circuit provides bias voltage.
9. audio frequency processing circuit according to claim 8, it is characterized in that, described voltage-stabilizing output circuit comprises electric capacity, diode, two resistance, and operational amplifier, connect described electric capacity on the first input end of described operational amplifier respectively, a described resistance, with described diode, described electric capacity is connected the audio frequency processing circuit earth terminal respectively with described diode, a described resistance connects power supply, short circuit between second input of described operational amplifier and the input, output connects another described resistance, and another described resistance connects the first input end of described operational amplifier.
10. earphone, described earphone comprise charging circuit, battery and as each described audio frequency processing circuit of claim 1 to 9; Described charging circuit connects charging inlet and the described battery of audio frequency apparatus, is described battery; Described battery is used to described audio frequency processing circuit power supply.
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|---|---|---|---|
| CN 201320071677 CN203167244U (en) | 2013-02-07 | 2013-02-07 | Audio processing circuit and earphone |
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|---|---|---|---|
| CN 201320071677 CN203167244U (en) | 2013-02-07 | 2013-02-07 | Audio processing circuit and earphone |
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| Country | Link |
|---|---|
| CN (1) | CN203167244U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104519444A (en) * | 2013-10-07 | 2015-04-15 | 新唐科技股份有限公司 | Method and apparatus for an integrated headset switch with reduced crosstalk noise |
-
2013
- 2013-02-07 CN CN 201320071677 patent/CN203167244U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104519444A (en) * | 2013-10-07 | 2015-04-15 | 新唐科技股份有限公司 | Method and apparatus for an integrated headset switch with reduced crosstalk noise |
| CN104519444B (en) * | 2013-10-07 | 2018-09-14 | 新唐科技股份有限公司 | Audio signal processing circuit and audio system |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130828 Effective date of abandoning: 20150617 |
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| RGAV | Abandon patent right to avoid regrant |