CN101790122A - Plosive eliminating circuit of audio system and mobile communication terminal - Google Patents
Plosive eliminating circuit of audio system and mobile communication terminal Download PDFInfo
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Abstract
The invention discloses a plosive eliminating circuit of an audio system and a mobile communication terminal. The plosive eliminating circuit includes an audio processing circuit, an electroacoustic device and a stopping condenser; audio signals output by the audio processing circuit are output by an audio transmission channel to the stopping condenser; AC signals are output to the electroacoustic device and transformed into sound signals for output after DC bias voltage in the audio signals is isolated by the stopping condenser; a voltage clamp circuit connected on the audio transmission channel is used for clamping a DC level of the audio transmission channel on the level of the DC bias voltage of the transmitted audio signals. As the voltage clamp circuit is smartly designed on the audio signal transmission channel, the invention eliminates plosives output by the electroacoustic device and improves the sound effect quality of the audio system. The plosive eliminating circuit of the invention has simple structure, has no additional hardware cost, cannot cause such problems as output delay and the like, and is suitable for promotion and application in the mobile communication terminals such as cell phones and palm computers.
Description
Technical field
The invention belongs to the audio signal processing technique field, specifically, relate to a kind ofly be used to eliminate the plosive treatment circuit that audio system produces and adopt described plosive to eliminate the mobile communication terminal of circuit design.
Background technology
The POP sound of audio system (plosive translated into usually in Chinese) mainly by the unexpected variation of each road audio electrical signal dc offset voltage, causes spike occurring at the capacitance place of outlet side connection electro-acoustic element and causes.These pulse signals comprise abundant radio-frequency component, and its medium frequency just can be heard by people's ear the noise between 20Hz～20KHz is changed into voice signal output by electro-acoustic element after.Change in voltage is big more, the time is short more, and then Shu Chu POP sound is just obvious more.
At simple audio system, the variation of voltage is mainly derived from the moment that audio codec CODEC opens and closes.And for the audio system of a complexity, same audio output interface (such as earphone or loud speaker) will in the face of the audio signal of different audio coding decoding CODEC output and different audio signals based on different DC biased voltage, its POP sound produces and not only derives from the opening and closing moment of audio codec CODEC, but also derives from the handoff procedure between each audio codec CODEC.
Fig. 1 has promptly described the mechanism of production of POP sound and the POP sound source of complication system.Audio codec CODEC1 or CODEC2 are being undertaken in the handoff procedure of audio frequency output channel by K switch 1 at the moment and CODEC1, the CODEC2 that open and close, the variation of level each time all can produce spike at capacitance C1 place, curve chart shown in left-half among Fig. 1, thus produce and output POP sound by electro-acoustic element (such as earphone or loud speaker etc.).
Eliminate the POP sound of audio system, most importantly solve the variation issue of dc offset voltage, promptly allow audio codec CODEC not produce the variation of voltage or do not allow the user hear the sound that change in voltage is brought in the moment of opening, close, switching.
At the problem of eliminating the POP sound, there has been a large amount of ripe schemes to use at present.Wherein effective solution roughly is divided into two classes: a class is that hardware is main circuit design scheme, and another kind of is that software is main programming scheme.
Hardware is that main solution mainly is to realize by a kind of emerging Cap-less art designs.It makes the dc offset voltage that exports audio-frequency power amplifier to by negative pressure technique is 0V, and promptly the voice signal by Cap-less audio frequency power amplifier U1 output all is an AC signal.The opening and closing of CODEC1 or CODEC2 just can not produce on circuit owing to direct voltage changes the spike that brings suddenly so, thereby can fundamentally eliminate the POP sound.The design principle of system is referring to shown in Figure 2.
What software was that main solution mainly utilizes be capacitance to the audio signal of electro-acoustic element is these characteristics of AC signal.If when producing the POP sound, with signal and the ground short circuit after the capacitance C1, as shown in Figure 3, promptly be connected K switch 2 closures between capacitance C1 negative pole and the ground by software control, behind capacitance C1 charging or discharge off, again itself and ground are opened circuit, from user perspective, can't hear the POP noise so.
General audio codec CODEC, its inside all can integrated low power audio frequency power amplifier, but is limited to cost pressure, and their integrated audio frequency power amplifiers can not have the Cap-less characteristic mostly.So, in the audio system that adopts this audio codec CODEC to make up, add a Cap-less power amplifier again, will certainly cause the waste of resource for eliminating the POP of system sound.In addition, at the audio system of complexity, the audio signal of each road CODEC output also can produce the POP sound, if after it is carried out processing and amplifying by the Cap-less power amplifier, understand the sense of hearing of interference user equally when the input of Cap-less power amplifier switches.Therefore, the Cap-less audio frequency power amplifier has various drawbacks on using.
Software is that main solution is started with from the signal of final output and solved POP mail topic, though can adapt to complicated audio system, but because its realization will depend on a large amount of software algorithms, and can not export useful signal in a period of time of signal ground, therefore can increase the time delay of whole system.
Based on above reason, how solve the POP mail topic of complex audio system by design scheme of hardware and software cheaply, be the subject matter that current audio system design field needs to be resolved hurrily.
Summary of the invention
The present invention suppresses the software solution existence output time-delay of POP sound, the problem that hardware solution is not suitable for the complex audio system in order to solve existing audio system, the audio system POP sound that has proposed a kind of brand-new design is eliminated circuit, be not only applicable to the audio system of any structure form, and circuit design is simple, cost is low, can not cause the time-delay of system's output.
For solving the problems of the technologies described above, the present invention proposes following two kinds and eliminate the plosive circuit design structure of audio system:
A kind of design is: audio frequency processing circuit, electro-acoustic element and capacitance are set in audio system; The audio signal of described audio frequency processing circuit output exports capacitance to through audio transmission channel, and after capacitance isolated out dc offset voltage in the audio signal, the output AC signal was to electro-acoustic element, to convert voice signal output to; Wherein, be connected with voltage clamp circuit on described audio transmission channel, described voltage clamp circuit is clamped down on the DC potential of audio transmission channel on the current potential of the dc offset voltage of institute's transmitting audio signal.
Further, the divider resistance that in described voltage clamp circuit, includes two series connection, described resistance series arm one end connects DC power supply, other end ground connection, its dividing potential drop node is connected on the described audio transmission channel, dispose the resistance of described divider resistance, make its dividing potential drop voltages at nodes equal the dc offset voltage of the audio signal that described audio transmission channel transmits.
Further again, described audio frequency processing circuit output multipath audio signal transfers to after a switching circuit carries out the passage gating through the multichannel voice frequency transmission channel respectively, exports described capacitance to; Described voltage clamp circuit is connected on the audio transmission channel that is communicated with under the described switching circuit normality.
For the system that is provided with earpiece audio passage and loudspeaker audio passage, audio frequency processing circuit is output one tunnel single-ended monophonic signal and the single-ended stereophonic signal of multichannel usually, the single-ended stereophonic signal of multichannel wherein transfers to loud speaker power amplifier and another switching circuit respectively by audio transmission channel after a switching circuit carries out the passage gating; Described another switching circuit switches between single-ended stereophonic signal that receives and single-ended monophonic signal, and the audio signal of output gating connects earphone to described capacitance through capacitance; Described voltage clamp circuit is connected on the audio transmission channel that is communicated with under described another switching circuit normality.
Preferably, in order to reduce the distortion factor of voice output, described capacitance preferably adopts tantalum electric capacity.
In order further to reach the purpose of design of balance output volume, raising signal to noise ratio, in the line of described capacitance and electro-acoustic element, be in series with resistance.Described resistance and capacitance form high pass filter, by increasing series resistance, can increase the resistance value of above-mentioned high pass filter, thereby reduce the low frequency cut-off points of high pass filter, that is to say the supper bass effect that can improve sound, also enlarged the adjustable extent of volume simultaneously.
Plosive based on above-mentioned audio system is eliminated circuit structure, and the present invention provides a kind of mobile communication terminal that adopts described plosive to eliminate circuit design again, is used to eliminate the POP sound by earphone output; Promptly by design voltage clamp circuit on the audio transmission channel before the capacitance that connects electro-acoustic element, and it is set clamps down on the dc offset voltage that voltage equals the audio signal transmitted in the described audio transmission channel, thereby the problem that the audio signal dc offset voltage of having avoided audio signal to be caused when switch or audio transmission conducting switching suddenlys change, make the capacitance place can not occur spike more thus, and then reached the purpose of design of eliminating the POP sound.
Eliminate circuit arrangement as second kind of plosive proposed by the invention, comprise the audio frequency amplifier of audio frequency processing circuit, electro-acoustic element and reception differential signal; Wherein, the embedding system voltage that the single-ended audio signal and the voltage clamp circuit of described audio frequency processing circuit output provided is made into differential signal, transfer to the differential signal input of audio frequency amplifier, described voltage clamp circuit clamp down on the dc offset voltage that voltage equals described single-ended audio signal.
Further, described audio frequency processing circuit output multipath audio signal, multipath audio signal connects the differential signal input of audio frequency amplifier by capacitance after a switching circuit carries out the passage gating.
Plosive based on second kind of conceptual design is eliminated circuit structure, and the present invention provides a kind of mobile communication terminal that adopts described plosive to eliminate circuit design again, is used to eliminate the POP sound by loud speaker output; Promptly by the single-ended audio signal of audio frequency processing circuit output and the dc offset voltage of described single-ended audio signal are made into differential signal, transferring to the difference audio frequency amplifier carries out exporting after power amplification is handled, thereby can eliminate the difference audio frequency amplifier because the dc offset voltage of the audio signal that two input receives is inconsistent, and the POP sound that produces during the switch audio frequency power amplifier that causes, to reach purpose of design of the present invention.
Compared with prior art, advantage of the present invention and good effect are: plosive of the present invention is eliminated circuit by design voltage clamp circuit dexterously on the audio signal transmission passage, thereby can eliminate the POP sound of earphone or loud speaker output, improve the audio quality of audio system.This circuit design structure is simple, realization is easy, increases the hardware cost of audio system hardly, can not produce problems such as output time-delay simultaneously, is adapted at applying in the mobile communication terminals such as mobile phone, palmtop PC.
After reading the detailed description of embodiment of the present invention in conjunction with the accompanying drawings, other characteristics of the present invention and advantage will become clearer.
Description of drawings
Fig. 1 is the schematic diagram that existing audio system produces the POP sound;
Fig. 2 is the circuit theory diagrams of the hardware solution of the existing POP of inhibition sound;
Fig. 3 is the principle schematic of the software solution of the existing POP of inhibition sound;
Fig. 4 is the circuit theory diagrams that audio system POP sound proposed by the invention is eliminated a kind of embodiment of circuit;
Fig. 5 is the circuit theory diagrams that audio system POP sound proposed by the invention is eliminated another embodiment of circuit;
Fig. 6 is the audio system circuit theory schematic diagram of a kind of mobile phone inside;
Fig. 7 is the circuit theory diagrams that the POP sound is eliminated a kind of embodiment of circuit 1 among Fig. 6.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is described in detail.
Audio system plosive elimination circuit of the present invention is started with from the dc offset voltage angle of audio signal, by the principle that research POP sound produces, sets up circuit at different audio systems, has proposed following two kinds of solutions:
One, for the audio signal that directly outputs to electro-acoustic element by capacitance, can on the transmission of audio signals passage, voltage clamp circuit be set, the DC potential of audio transmission channel is clamped down on the amplitude of the dc offset voltage of institute's transmitting audio signal, thereby when the absence of audio signal transmits, because voltage clamp circuit is to the charging effect of capacitance, can be so that the voltage on the capacitance remains near the amplitude of dc offset voltage of audio signal, thereby when audio signal switch or switching, can not cause the sudden change of voltage on the capacitance, thereby avoided the generation of capacitance place spike, reached the purpose of design of eliminating the POP sound.
Two, for the audio signal of line output again after need handling by power amplifier, because relatively more current in the industry audio frequency amplifier all is the difference input form, if the bias voltage of two signals of difference audio frequency amplifier input is inconsistent, will cause when opening or closing audio frequency amplifier, producing the POP sound.The present invention is for head it off, single-ended audio signal for audio frequency processing circuit output, utilize the direct voltage and the described single-ended audio signal of voltage clamp circuit output to be made into one group of differential signal, and make the dc offset voltage that voltage just equals described single-ended audio signal of clamping down on that voltage clamp circuit provides.So, the direct voltage that can guarantee to output to two differential signal inputs of audio frequency amplifier equates, thereby realized effective elimination of system POP sound.
Elaborate concrete establishment structure and the operation principle thereof that described plosive is eliminated circuit below by two specific embodiments.
Embodiment one, and referring to shown in Figure 4, the audio system of present embodiment is made up of major parts such as audio frequency processing circuit, capacitance C6023/C6026 and electro-acoustic elements.Wherein, the audio signal of exporting by audio frequency processing circuit can be single-ended monophonic signal, also can be single-ended stereophonic signal.Present embodiment is that example describes with single-ended stereophonic signal MIX_L, MIX_R.On the audio transmission channel of transmission described single-ended stereophonic signal MIX_L, MIX_R, voltage clamp circuit is set, as shown in Figure 4, the voltage clamp circuit of being made up of divider resistance R6003, R6005 and DC power supply VMSMP is connected on the transmission channel of the single-ended audio signal MIX_L of transmission L channel, after being about to divider resistance R6003 and R6005 series connection, one end connects DC power supply VMSMP, other end ground connection, its dividing potential drop node is connected on the audio transmission channel of MIX_L.Dc offset voltage amplitude according to the MIX_L signal of audio frequency processing circuit output, dispose the resistance of described divider resistance R6003, R6005, make the dc offset voltage amplitude of clamping down on voltage magnitude and MIX_L signal at its dividing potential drop node place suitable, such as equating or about equally, even thereby when on the audio transmission channel of MIX_L, not having signal, also can exist a clamp down on voltage suitable to be capacitance C6026 charging, the magnitude of voltage on the maintenance capacitance C6026 with the dc offset voltage of MIX_L signal.So, open, close at audio frequency processing circuit or moment of switch audio transmission channel, can on capacitance C6026, not produce spike, thereby avoid the generation of POP sound.
In order to guarantee to clamp down on the precision of voltage, present embodiment preferably adopts divider resistance R6003, the R6005 of F precision to make up described voltage clamp circuit, and choosing of its resistance can adopt following algorithm to determine:
Dc offset voltage=the VMSMP/ of MIX_L signal (R6003+R6005) * R6005.
In like manner, on the transmission channel of the single-ended audio signal MIX_R of R channel that audio frequency processing circuit is exported, can connect the voltage clamp circuit of forming by divider resistance R6004, R6011 and DC power supply VMSMP, as shown in Figure 4, its connected mode is the same, dispose the dc offset voltage amplitude that voltage magnitude is the MIX_R signal of clamping down at its dividing potential drop node place, perhaps about equally, can eliminate the spike that capacitance C6023 place produces, to avoid the output of POP sound.
In the present embodiment, described capacitance C6023, C6026 preferably adopt tantalum electric capacity to carry out circuit design, and characteristics such as volume is little, capacity height that it has can be saved the area of pcb board greatly.And, because tantalum electric capacity has the advantage of low ESR (equivalent series resistance), can prevent that therefore audio signal from excessive voltage jump taking place, thereby help further to reduce the POP sound, reduce the distortion factor of voice output.
For the audio system that can export multipath audio signal simultaneously, switching circuit need be set, on audio transmission channel to realize accurate switching to output audio signal.As shown in Figure 4, for example audio system can be exported single-ended monophonic signal EAR20 and single-ended stereophonic signal MIX_L, MIX_R simultaneously, utilizes switch chip S6001 that these two groups of audio transmission channel are carried out gating and switches.Wherein, single-ended monophonic signal EAR20 is divided into two-way, is connected with wherein one group of switch passage IN1, IN2 of switch chip S6001 respectively; Other one group of switch passage NO1, the NO2 of switch chip S6001 connects the transmission channel of single-ended stereophonic signal MIX_L, MIX_R; Common port COM1, the COM2 of switch chip S6001 connect capacitance C6023, C6026 respectively, control end receives the control signal that master chip sends in the audio system, such as the GPIO46 mouth that connects master chip, receive the high level or the low level control signal of master chip output, with gating one group of audio signal wherein, transfer to after capacitance C6023, C6026 filter out wherein dc offset voltage, output AC signal IO_HPOUTL, IO_HPOUTR are to electro-acoustic element, to convert voice signal output to.
In order under the prerequisite that guarantees elimination POP sound, can further to simplify circuit structure, present embodiment preferably only is arranged on voltage clamp circuit on the audio transmission channel that is communicated with under the switch chip S6001 normality, on the audio transmission channel of the single-ended stereophonic signal MIX_L of transmission as shown in Figure 4, MIX_R, making the voltage of clamping down on of voltage clamp circuit output can be capacitance C6023, C6026 charging in time.So, even switch to moment of other one group of switch passage at switch chip S6001 and since the voltage on capacitance C6023, the C6026 with switch after the dc offset voltage of audio signal suitable, therefore, voltage jump can be do not produced, thereby the POP sound can not be occurred.
Certainly, can voltage clamp circuit be set all on the multichannel voice frequency transmission channel, present embodiment does not specifically limit this yet.
Embodiment two, and referring to shown in Figure 5, the audio system of present embodiment is made up of major parts such as audio frequency processing circuit, audio frequency amplifier U2/U3 and electro-acoustic elements.Wherein, the audio signal of exporting by audio frequency processing circuit can be single-ended audio signal, such as single-ended stereophonic signal MIX_L, MIX_R; Also can be the difference audio signal, such as AUXOP, AUXON.Because relatively more current in the industry audio frequency amplifier all is the difference input form, as shown in Figure 5 audio frequency amplifier U2, U3, if the dc offset voltage of two signals of its differential input end is inconsistent, will make audio frequency amplifier U2, U3 at switch moment generation POP sound.If audio frequency amplifier U2, U3 directly receive conventional difference audio signal AUXOP, AUXON, because the dc offset voltage among difference audio signal AUXOP, the AUXON equates, therefore, can when opening or closing audio frequency amplifier U2, U3, not produce the POP sound.
But, such as MIX_L, MIX_R, it need be made into and transfer to audio frequency amplifier U2, U3 behind the differential signal again and carry out power amplification and handle, and then drive the loud speaker output sound for single-ended audio signal.In order to realize eliminating the purpose of design of POP sound, what present embodiment adopted voltage clamp circuit output clamps down on voltage with single-ended audio signal is made into differential signal, transfers to audio frequency amplifier and carries out the power amplifier processing.Wherein, voltage clamp circuit provides clamps down on the dc offset voltage amplitude that voltage magnitude should equal to be made into it single-ended audio signal of differential signal.The voltage of clamping down on as the output of the voltage clamp circuit be made up of divider resistance R6032, R6033 and DC power supply VMSMP among Fig. 5 can be made into differential signal with single-ended right channel audio signal MIX_R, connects two differential input ends of audio frequency amplifier U2.According to the dc offset voltage configuration divider resistance R6032 of single-ended right channel audio signal MIX_R, the resistance of R6033, make its dividing potential drop voltages at nodes value just equal the dc offset voltage of MIX_R signal, so just can eliminate POP sound by right channel loudspeaker output.In like manner, can utilize the voltage of clamping down on of other one road voltage clamp circuit output to be made into differential signal with it, after exporting audio frequency amplifier U3 to and carrying out the power amplifier processing, through the left channel loudspeaker output sound for single-ended left channel audio signal MIX_L.Such as the voltage clamp circuit of forming by divider resistance R6034, R6035 and DC power supply VMSMP among Fig. 5, as long as the resistance of configuration divider resistance R6034, R6035, make the dc offset voltage that voltage equals single-ended left channel audio signal MIX_L of clamping down on of its dividing potential drop node place output, can avoid left channel loudspeaker output POP sound.Among Fig. 5, filter capacitor C6024, the C6008 that connects voltage clamp circuit dividing potential drop node can play to eliminate and disturb, stablize the purpose of design of clamping down on voltage.
In order to satisfy the switching output requirement of multipath audio signal, present embodiment has designed switching circuit on the multichannel voice frequency transmission channel, as the switch chip S6003 among Fig. 5, and the wherein corresponding connection of differential signal that is made into of one group of switch ways NCn and single-ended audio signal; The corresponding connection of other one group of switch ways NOn with differential signal AUXOP, AUXON; Its common port COMn connects the differential input end of audio frequency amplifier U2, U3 by capacitance C6022, C6018, C6017, C6020; Control end A0, A1 connect the master chip in the audio frequency processing circuit, such as the GPIO51 mouth that connects master chip, receive the control signal of master chip output, and then which group differential signal transmission of definite gating handles to audio frequency amplifier U2, U3, the audio signal of choosing with output.
Owing to the appearance value of the capacitance C6022, the C6018 that are connected the differential input end of audio frequency amplifier U2, U3, C6017, C6020 is very little, therefore signal lag is very little, when voice-grade channel switch or switching, produce thereon voltage jump the influence that can cause taken into account by audio frequency amplifier U2, U3, therefore, need not consider to produce the problem of POP sound owing to the setting of capacitance C6022, C6018, C6017, C6020.
Be example with the mobile phone below, specifically set forth described POP sound and eliminate the concrete application of circuit in mobile phone circuit.
Embodiment three, referring to shown in Figure 6, along with becoming stronger day by day of cell-phone function, present many high-end mobile phone all possesses complicated audio system, such as supporting playing functions such as MP3, MP4, FM audio broadcasting, therefore need consider the output form of various audio signals comprehensively.
As shown in Figure 6, voice signal during mobile phone communication and keypad tone are by being integrated in audio codec CODEC1 in the master chip with the form output of difference monophonic signal AUXOP, AUXON and single-ended monophonic signal EAR20; After audio signal in MP3, the MP4 file can be handled by audio codec CODEC2, with the form output of single-ended stereophonic signal HPOUTR, HPOUTL; Then can be for FM broadcasting by after the audio codec CODEC3 processing, with the form output of single-ended stereophonic signal FM_OUTR, FM_OUTL.Wherein, export stereophone by the single-ended monophonic signal EAR20 of CODEC1 output with by the single-ended stereophonic signal that CODEC2, CODEC3 export to by POP sound elimination circuit 1, when the user is inserted into earphone on the mobile phone, by the earphone output audio signal.Switch single-ended stereophonic signal MIX_L, the MIX_R of output and eliminate circuit 1 by difference monophonic signal AUXOP, the AUXON of CODEC1 output with by the POP sound, when then on mobile phone, not inserting earphone, after eliminating circuit 2 and export audio frequency amplifier U to and carry out power amplification and handle by the POP sound, drive the boombox output audio signal.
Wherein, the POP sound is eliminated circuit 1 and can be adopted the form design that increases switch chip S6002 on the basis of Fig. 4 circuit to realize, as shown in Figure 7.After the single-ended stereophonic signal that utilizes switch chip S6002 that CODEC2, CODEC3 are exported switched, the audio signal (being designated as MIX_L, MIX_R) of output gating was respectively to switch chip S6001 and loud speaker power amplifier.Switch chip S6001 exports the stereophone output sound to through capacitance C6023, C6026 after the single-ended monophonic signal EAR20 of audio signal MIX_L, MIX_R and CODEC1 output is carried out gating.
Because CODEC internal audio frequency output adopts push-pull output circuit more.The structures shape of push-pull circuit its output voltage probably about VCC/2, and push-pull circuit is not when working, CODEC output mostly is high impedance status.These characteristics provide the foundation of design and the portability of having guaranteed this circuit for us.By the adjustment of supply power voltage, the operation level of three CODEC all can be fixed on about 2.8V, the dc offset voltage amplitude that so just can guarantee the audio signal that their are exported is about 1.4V.Be chosen on the audio transmission channel of transmitting MIX_L, MIX_R signal voltage clamp circuit is set, and make its dividing potential drop voltages at nodes value about 1.4V, can eliminate POP sound by earphone output.
Because the volume difference of each CODEC output is bigger, especially single-ended stereophonic signal FM_OUTR, the FM_OUTL of CODEC# 3 output, the level difference between the volumes at different levels is less, and to compare volume integral body higher with other CODEC.Output volume for the balance earphone, present embodiment one tunnel resistance R 6038 and the R6039 that in the connection line of capacitance C6023, C6026 and stereophone, connected separately again, as shown in Figure 6, agree with people's ear demand thereby can make, and guaranteed the consistency of all CODEC output sound sizes by the volume of CODEC3 output.Simultaneously, the introducing of these two resistance has also improved the signal to noise ratio of audio system, has reduced the noise of earphone.
Because earphone and resistance R 6038/R6039 are that resistive device, capacitance C6023/C6026 are capacitive devices, according to the ABC of RC filter, two parts can be formed a high pass filter, and the algorithm that its filter 3dB is ordered is f=1/2 π RC.Present embodiment has also just reduced f by increasing resistance R 6038/R6039, makes the low-frequency cut-off frequency step-down of audio signal, thereby has improved the supper bass effect of sound.
The POP sound is eliminated circuit 2 and can be adopted circuit structure design shown in Figure 5 to realize that present embodiment is no longer given unnecessary details at this.
Table 1 has been listed the control truth table of related master chip GPIO mouth in the POP sound elimination circuit 1,2.Wherein, master chip outputs control signals to switch chip S6002 by its GPIO46, to realize the effective switching to CODEC2, CODEC3 output audio signal.As can be seen from Table 1: as long as distinguish out the current earphone connection that whether has, know the audio signal that needs to play which CODEC output again, only need the state correspondence of the employed GPIO mouth of above control is come just can easily realize, and do not need to wait for time-delay.
| ??GPIO51 | ??GPIO46 | ??GPIO47 | |
| EAR20 exports from earphone | ??X | ??0 | ??X |
| HPOUTL/HPOUTR exports from earphone | ??X | ??1 | ??0 |
| FM_OUTR/FM_OUTL exports from earphone | ??X | ??1 | ??1 |
| HPOUTL/HPOUTR exports from loud speaker | ??0 | ??1 | ??0 |
| FM_OUTR/FM_OUTL exports from loud speaker | ??0 | ??1 | ??1 |
| AUXOP/AUXON exports from loud speaker | ??1 | ??X | ??X |
Table 1
POP sound of the present invention is eliminated circuit by the number of change switch chip and the supported port number of switch chip, can realize the POP sound of other multichannel or SCVF single channel voice frequency signal output system is eliminated, be particluarly suitable for promoting the use of on the mobile communication terminals such as mobile phone, palmtop PC.
Certainly; the above only is a kind of preferred implementation of the present invention, should be pointed out that for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, any improvements and modifications of being made all should be considered as protection scope of the present invention.
Claims (10)
1. the plosive of an audio system is eliminated circuit, comprises audio frequency processing circuit, electro-acoustic element and capacitance; The audio signal of described audio frequency processing circuit output exports capacitance to through audio transmission channel, and after capacitance isolated out dc offset voltage in the audio signal, the output AC signal was to electro-acoustic element, to convert voice signal output to; It is characterized in that: be connected with voltage clamp circuit on described audio transmission channel, described voltage clamp circuit is clamped down on the DC potential of audio transmission channel on the current potential of the dc offset voltage of institute's transmitting audio signal.
2. the plosive of audio system according to claim 1 is eliminated circuit, it is characterized in that: the divider resistance that in described voltage clamp circuit, includes two series connection, described resistance series arm one end connects DC power supply, other end ground connection, its dividing potential drop node is connected on the described audio transmission channel, dispose the resistance of described divider resistance, make its dividing potential drop voltages at nodes equal the dc offset voltage of the audio signal that described audio transmission channel transmits.
3. the plosive of audio system according to claim 1 and 2 is eliminated circuit, it is characterized in that: described audio frequency processing circuit output multipath audio signal, transfer to after a switching circuit carries out the passage gating through the multichannel voice frequency transmission channel respectively, export described capacitance to; Described voltage clamp circuit is connected on the audio transmission channel that is communicated with under the described switching circuit normality.
4. the plosive of audio system according to claim 1 and 2 is eliminated circuit, it is characterized in that: described audio frequency processing circuit is exported one tunnel single-ended monophonic signal and the single-ended stereophonic signal of multichannel, the single-ended stereophonic signal of multichannel wherein transfers to loud speaker power amplifier and another switching circuit respectively by audio transmission channel after a switching circuit carries out the passage gating; Described another switching circuit switches between single-ended stereophonic signal that receives and single-ended monophonic signal, and the audio signal of output gating connects earphone to described capacitance through capacitance; Described voltage clamp circuit is connected on the audio transmission channel that is communicated with under described another switching circuit normality.
5. the plosive of audio system according to claim 1 and 2 is eliminated circuit, and it is characterized in that: described capacitance is a tantalum electric capacity.
6. the plosive of audio system according to claim 1 and 2 is eliminated circuit, it is characterized in that: be in series with resistance in the line of described capacitance and electro-acoustic element.
7. a mobile communication terminal is characterized in that: include as the plosive of the described audio system of each claim in the claim 1 to 6 and eliminate circuit.
8. the plosive of an audio system is eliminated circuit, comprises the audio frequency amplifier of audio frequency processing circuit, electro-acoustic element and reception differential signal; It is characterized in that: the voltage of clamping down on that the single-ended audio signal and the voltage clamp circuit of described audio frequency processing circuit output provided is made into differential signal, transfer to the differential signal input of audio frequency amplifier, described voltage clamp circuit clamp down on the dc offset voltage that voltage equals described single-ended audio signal.
9. the plosive of audio system according to claim 8 is eliminated circuit, it is characterized in that: described audio frequency processing circuit output multipath audio signal, multipath audio signal connects the differential signal input of audio frequency amplifier by capacitance after a switching circuit carries out the passage gating.
10. a mobile communication terminal is characterized in that: include the plosive elimination circuit of audio system as claimed in claim 8 or 9.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010109891.6A CN101790122B (en) | 2010-02-06 | 2010-02-06 | Plosive eliminating circuit of audio system and mobile communication terminal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010109891.6A CN101790122B (en) | 2010-02-06 | 2010-02-06 | Plosive eliminating circuit of audio system and mobile communication terminal |
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| Publication Number | Publication Date |
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| CN101790122A true CN101790122A (en) | 2010-07-28 |
| CN101790122B CN101790122B (en) | 2014-05-14 |
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| CN101986668A (en) * | 2010-09-03 | 2011-03-16 | 深圳市中兴移动通信有限公司 | Circuit and method for eliminating POP tone in dual-mode handset earphone communication |
| CN102056052A (en) * | 2010-11-28 | 2011-05-11 | 青岛海信移动通信技术股份有限公司 | Audio switching circuit and mobile terminal with same |
| CN102638741A (en) * | 2011-02-11 | 2012-08-15 | 上海闻泰电子科技有限公司 | Method for fully eliminating earphone POP noise |
| CN103139689A (en) * | 2011-11-23 | 2013-06-05 | 安凯(广州)微电子技术有限公司 | Device and method for eliminating popping sound of earphone |
| CN103533484A (en) * | 2012-07-03 | 2014-01-22 | 安凯(广州)微电子技术有限公司 | Rapid noise elimination circuit |
| CN104272588A (en) * | 2012-05-02 | 2015-01-07 | 高通股份有限公司 | Split capacitors scheme for suppressing overshoot voltage glitches in class d amplifier output stage |
| CN104796821A (en) * | 2015-05-06 | 2015-07-22 | 岭南师范学院 | Audio signal assisting device |
| CN104967946A (en) * | 2015-06-10 | 2015-10-07 | 上海芯望电子技术有限公司 | Multichannel audio processor |
| CN105383376A (en) * | 2015-12-04 | 2016-03-09 | 吉林航盛电子有限公司 | Pedestrian sound warning device, based on environmental sound feedback, of new energy vehicle |
| CN105792069A (en) * | 2014-12-26 | 2016-07-20 | 联芯科技有限公司 | Headset base interface circuit |
| CN107547982A (en) * | 2016-06-28 | 2018-01-05 | 来得声有限公司 | Audio frequency apparatus and audio output port |
| CN108417193A (en) * | 2018-06-12 | 2018-08-17 | 杭州百隆电子有限公司 | A kind of electronic device driving circuit and its high resistance circuit and driving method |
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| CN101052239A (en) * | 2006-04-03 | 2007-10-10 | 英华达(上海)电子有限公司 | High frequency circuit and its method for eliminating earphone noise |
| CN201153322Y (en) * | 2007-12-06 | 2008-11-19 | 中兴通讯股份有限公司 | Audio circuit |
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| CN101986668B (en) * | 2010-09-03 | 2014-11-26 | 深圳市中兴移动通信有限公司 | Circuit and method for eliminating POP tone in dual-mode handset earphone communication |
| CN101986668A (en) * | 2010-09-03 | 2011-03-16 | 深圳市中兴移动通信有限公司 | Circuit and method for eliminating POP tone in dual-mode handset earphone communication |
| CN102056052A (en) * | 2010-11-28 | 2011-05-11 | 青岛海信移动通信技术股份有限公司 | Audio switching circuit and mobile terminal with same |
| CN102056052B (en) * | 2010-11-28 | 2014-02-12 | 青岛海信移动通信技术股份有限公司 | Audio switching circuit and mobile terminal with same |
| CN102638741A (en) * | 2011-02-11 | 2012-08-15 | 上海闻泰电子科技有限公司 | Method for fully eliminating earphone POP noise |
| CN102638741B (en) * | 2011-02-11 | 2017-10-13 | 上海闻泰电子科技有限公司 | The method of earphone POP noise is completely eliminated |
| CN103139689A (en) * | 2011-11-23 | 2013-06-05 | 安凯(广州)微电子技术有限公司 | Device and method for eliminating popping sound of earphone |
| CN104272588A (en) * | 2012-05-02 | 2015-01-07 | 高通股份有限公司 | Split capacitors scheme for suppressing overshoot voltage glitches in class d amplifier output stage |
| CN104272588B (en) * | 2012-05-02 | 2017-05-03 | 高通股份有限公司 | Method and circuit for suppressing overshoot voltage glitches in class d amplifier |
| CN103533484A (en) * | 2012-07-03 | 2014-01-22 | 安凯(广州)微电子技术有限公司 | Rapid noise elimination circuit |
| CN105792069A (en) * | 2014-12-26 | 2016-07-20 | 联芯科技有限公司 | Headset base interface circuit |
| CN105792069B (en) * | 2014-12-26 | 2019-04-16 | 联芯科技有限公司 | A kind of earphone base interface circuit |
| CN104796821A (en) * | 2015-05-06 | 2015-07-22 | 岭南师范学院 | Audio signal assisting device |
| CN104967946A (en) * | 2015-06-10 | 2015-10-07 | 上海芯望电子技术有限公司 | Multichannel audio processor |
| CN105383376A (en) * | 2015-12-04 | 2016-03-09 | 吉林航盛电子有限公司 | Pedestrian sound warning device, based on environmental sound feedback, of new energy vehicle |
| CN105383376B (en) * | 2015-12-04 | 2018-02-23 | 吉林航盛电子有限公司 | A kind of new-energy automobile pedestrian's sound alarming device based on ambient sound feedback |
| CN107547982A (en) * | 2016-06-28 | 2018-01-05 | 来得声有限公司 | Audio frequency apparatus and audio output port |
| CN108417193A (en) * | 2018-06-12 | 2018-08-17 | 杭州百隆电子有限公司 | A kind of electronic device driving circuit and its high resistance circuit and driving method |
| CN108417193B (en) * | 2018-06-12 | 2024-03-22 | 杭州百隆电子有限公司 | Electronic device driving circuit, high-resistance circuit thereof and driving method |
| CN110113692A (en) * | 2019-05-21 | 2019-08-09 | 合肥联宝信息技术有限公司 | A kind of sound signal outputting device, computer equipment and its control method |
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Address after: 266071 Shandong city of Qingdao province Jiangxi City Road No. 11 Applicant after: Qingdao Hisense Mobile Communication Technology Co., Ltd. Address before: 266100 Zhuzhou Road, Laoshan District, Shandong, No. 151, No. Applicant before: Qingdao Hisense Mobile Communication Technology Co., Ltd. |
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