CN101790122B - Plosive eliminating circuit of audio system and mobile communication terminal - Google Patents
Plosive eliminating circuit of audio system and mobile communication terminal Download PDFInfo
- Publication number
- CN101790122B CN101790122B CN201010109891.6A CN201010109891A CN101790122B CN 101790122 B CN101790122 B CN 101790122B CN 201010109891 A CN201010109891 A CN 201010109891A CN 101790122 B CN101790122 B CN 101790122B
- Authority
- CN
- China
- Prior art keywords
- audio
- signal
- circuit
- output
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
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 audio signal processing technique field, specifically, relate to a kind of for eliminating the plosive treatment circuit that audio system produces and adopting described plosive to eliminate the mobile communication terminal of circuit design.
Background technology
The POP sound (plosive translated into conventionally in Chinese) of audio system, the unexpected variation of main You Ge road audio electrical signal DC offset voltage, causes the capacitance place that connects electro-acoustic element at outlet side to occur that spike causes.These pulse signals comprise abundant radio-frequency component, and its medium frequency is changed into by electro-acoustic element at the noise between 20Hz～20KHz after voice signal output, just can be heard by people's ear.Change in voltage is larger, the time is shorter, and the POP sound of output is just more obvious.
For simple audio system, the variation of voltage is mainly derived from the moment that audio codec CODEC opens and closes.And for a complicated audio system, 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 described the mechanism of production of POP sound and the POP sound of complication system source.Audio codec CODEC1 or CODEC2 at the moment opening and closing and CODEC1, CODEC2 being undertaken in the handoff procedure of audio frequency output channel by K switch 1, the variation of level each time all can produce at capacitance C1 place spike, curve chart as shown in left-half in Fig. 1, thus produce and export 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, allow audio codec CODEC not produce the variation of voltage or do not allow user hear the sound that change in voltage is brought in the moment of opening, close, switching.
For the problem of eliminating POP sound, there is a large amount of ripe schemes to apply at present.Wherein effective solution is roughly 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 is mainly to realize by a kind of emerging Cap-less art designs.The DC offset voltage that it makes to export to audio-frequency power amplifier by negative pressure technique is 0V, is all AC signal by the voice signal of Cap-less audio frequency power amplifier U1 output.The opening and closing of CODEC1 or CODEC2 just can not produce because direct voltage changes suddenly the spike bringing on circuit so, thereby can fundamentally eliminate POP sound.The design principle of system is shown in Figure 2.
What software was that main solution mainly utilizes is that capacitance is this feature of AC signal to the audio signal of electro-acoustic element.If in producing POP sound, by signal and ground short circuit after capacitance C1, as shown in Figure 3, be connected to K switch 2 closures between capacitance C1 negative pole and ground by software control, after capacitance C1 charging or discharge off, again itself and ground are opened circuit, from user perspective, can't hear POP noise so.
General audio codec CODEC, the audio frequency power amplifier that its inside all can integrated small power, but being limited to cost pressure, their integrated audio frequency power amplifiers can not have Cap-less characteristic mostly.So, in the audio system that adopts this audio codec CODEC to build, add again a Cap-less power amplifier for eliminating system POP sound, will certainly cause the waste of resource.In addition, for complicated audio system, the audio signal of each road CODEC output, in the time that the input of Cap-less power amplifier switches, also can produce POP sound, if it is amplified after processing by Cap-less power amplifier, understands equally the sense of hearing of interference user.Therefore, Cap-less audio frequency power amplifier has various drawbacks in application.
Software is that main solution is started with and solved POP mail topic from the signal of final output, although can adapt to complicated audio system, but because its realization will depend on a large amount of software algorithms, and in a period of time of signal ground, can not export useful signal, 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 a current audio system field subject matter urgently to be resolved hurrily.
Summary of the invention
The present invention suppresses POP sound software solution in order to solve existing audio system exists output time delay, hardware solution not to be suitable for the problem of complex 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 version, and circuit design is simple, cost is low, can not cause the time delay of system 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 isolates out the DC offset voltage in audio signal, output AC signal is to electro-acoustic element, to convert voice signal output to; Wherein, in described audio transmission channel, be connected with voltage clamp circuit, 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 transmission of audio signal.
Further, in described voltage clamp circuit, include the divider resistance of two series connection, described resistance series arm one end connects DC power supply, other end ground connection, its dividing potential drop node is connected in described audio transmission channel, configure the resistance of described divider resistance, make the voltage of its dividing potential drop Nodes equal the DC offset voltage of the audio signal that described audio transmission channel transmits.
Further again, described audio frequency processing circuit output multi-channel audio signal, transfers to a switching circuit through multichannel voice frequency transmission channel respectively and carries out after passage gating, exports described capacitance to; Described voltage clamp circuit is connected in the audio transmission channel being communicated with under described switching circuit normality.
For the system that is provided with earpiece audio passage and loudspeaker audio passage, audio frequency processing circuit is the output one single-ended monophonic signal in tunnel and the single-ended stereophonic signal of multichannel conventionally, the single-ended stereophonic signal of multichannel wherein, after a switching circuit carries out passage gating, transfers to respectively loud speaker power amplifier and another switching circuit by audio transmission channel; Described another switching circuit switches between the single-ended stereophonic signal receiving and single-ended monophonic signal, and the audio signal of output gating is to described capacitance, through capacitance frames connecting with headphone; Described voltage clamp circuit is connected in the audio transmission channel being 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 expanded the adjustable extent of volume simultaneously.
Plosive based on above-mentioned audio system is eliminated circuit structure, and the present invention provides again a kind of mobile communication terminal that adopts described plosive to eliminate circuit design, for eliminating the POP sound of exporting by earphone; By design voltage clamp circuit in the audio transmission channel before the capacitance that connects electro-acoustic element, and it is set clamps down on voltage and equal the DC offset voltage of the audio signal of transmitting in described audio transmission channel, thereby the problem that the audio signal DC offset voltage of having avoided audio signal to cause in the time of switch or audio transmission conducting switching suddenlys change, make thus capacitance place can not occur again spike, and then reached the purpose of design of eliminating POP sound.
Eliminate circuit arrangement as the second 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 voltage processed that the single-ended audio signal that described audio frequency processing circuit is exported and voltage clamp circuit provide is made into differential signal, transfer to the differential signal input of audio frequency amplifier, the DC offset voltage of clamping down on voltage and equal described single-ended audio signal of described voltage clamp circuit.
Further, described audio frequency processing circuit output multi-channel audio signal, multipath audio signal, after a switching circuit carries out passage gating, connects the differential signal input of audio frequency amplifier by capacitance.
Plosive based on first scheme design is eliminated circuit structure, and the present invention provides again a kind of mobile communication terminal that adopts described plosive to eliminate circuit design, for eliminating the POP sound of exporting by loud speaker; 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 difference audio frequency amplifier carries out after power amplification is processed exporting, thereby the DC offset voltage that can eliminate the audio signal that difference audio frequency amplifier receives due to two input is inconsistent, and the POP sound producing when the switch audio frequency power amplifier causing, 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 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 hardly the hardware cost of audio system, can not produce the problems such as output time delay simultaneously, is adapted at applying in the mobile communication terminal such as mobile phone, palmtop PC.
Read by reference to the accompanying drawings after the detailed description of embodiment of the present invention, it is clearer that the other features and advantages of the invention will become.
Accompanying drawing explanation
Fig. 1 is the schematic diagram that existing audio system produces POP sound;
Fig. 2 is the circuit theory diagrams of the hardware solution of existing inhibition POP sound;
Fig. 3 is the principle schematic of the software solution of existing inhibition POP 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 a kind of audio system circuit theory schematic diagram of interior of mobile phone;
Fig. 7 is the circuit theory diagrams that in Fig. 6, POP sound is eliminated a kind of embodiment of circuit 1.
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, and the principle producing by research POP sound, sets up circuit for 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 in the transmission channel of audio signal, voltage clamp circuit be set, the DC potential of audio transmission channel is clamped down in the amplitude of the DC offset voltage of institute's transmission of audio signal, thereby in the time that absence of audio signal transmits, due to the charging effect of voltage clamp circuit to capacitance, can make the voltage on capacitance remain near the amplitude of DC offset voltage of audio signal, thereby in the time of audio signal switch or switching, can not cause the sudden change of voltage on capacitance, thereby avoid the generation of capacitance place spike, reach the purpose of design of eliminating POP sound.
Two, for the audio signal of line output again after need to processing by power amplifier, because more current in the industry audio frequency amplifier is all difference input form, if the bias voltage of two signals of difference audio frequency amplifier input is inconsistent, will cause producing POP sound in opening or closing audio frequency amplifier.The present invention is for head it off, for the single-ended audio signal of audio frequency processing circuit output, utilize direct voltage and the described single-ended audio signal of voltage clamp circuit output to be made into one group of differential signal, and the DC offset voltage of clamping down on voltage and just equal described single-ended audio signal that makes that voltage clamp circuit provides.So, can guarantee that the direct voltage of two differential signal inputs that output to audio frequency amplifier equates, thereby realize effective elimination of system POP sound.
Elaborate concrete assembling structure and the operation principle thereof of described plosive elimination circuit below by two specific embodiments.
Embodiment mono-, shown in Figure 4, the audio system of the 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, can be also single-ended stereophonic signal.The present embodiment describes as an example of single-ended stereophonic signal MIX_L, MIX_R example.In 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 being made up of divider resistance R6003, R6005 and DC power supply VMSMP is connected in the transmission channel of the single-ended audio signal MIX_L of transmission L channel, after 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 in the audio transmission channel of MIX_L.According to the DC offset voltage amplitude of the MIX_L signal of audio frequency processing circuit output, configure the resistance of described divider resistance R6003, R6005, make the DC offset voltage amplitude of clamping down on voltage magnitude and MIX_L signal of its dividing potential drop Nodes suitable, such as equal or roughly equal, even thereby there is no signal in the audio transmission channel of MIX_L time, also can have a clamp down on voltage suitable with the DC offset voltage of MIX_L signal is capacitance C6026 charging, keeps the magnitude of voltage on capacitance C6026.So, open, close or switch the moment of audio transmission channel at audio frequency processing circuit, can on capacitance C6026, not produce spike, thereby avoided the generation of POP sound.
In order to guarantee to clamp down on the precision of voltage, the present embodiment preferably adopts divider resistance R6003, the R6005 of F precision to build described voltage clamp circuit, and choosing of its resistance can adopt following algorithm to determine:
DC offset voltage=VMSMP/ (R6003+R6005) * R6005 of MIX_L signal.
In like manner, in the transmission channel of the single-ended audio signal MIX_R of R channel exporting at audio frequency processing circuit, can connect the voltage clamp circuit being formed by divider resistance R6004, R6011 and DC power supply VMSMP, as shown in Figure 4, its connected mode is the same, configure the DC offset voltage amplitude that voltage magnitude is MIX_R signal of clamping down on of its dividing potential drop Nodes, or roughly equal, 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 it has, and volume is little, capacity high, can greatly save the area of pcb board.And, because tantalum electric capacity has advantages of low ESR (equivalent series resistance), therefore can prevent that audio signal from excessive voltage jump occurring, thereby contribute to further to reduce POP sound, reduce the distortion factor of voice output.
For the audio system of output multi-channel audio signal simultaneously, switching circuit need to be set in audio transmission channel, to realize the 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 to carry out gating switching to these two groups of audio transmission channel.Wherein, single-ended monophonic signal EAR20 is divided into two-way, is connected respectively with wherein one group of switch passage IN1, the IN2 of switch chip S6001; 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 respectively capacitance C6023, C6026, the control signal that in control end audio reception system, master chip sends, such as connecting the GPIO46 mouth of master chip, receive high level or the low level control signal of master chip output, with wherein one group of audio signal of gating, transferring to capacitance C6023, C6026 filters out after DC offset voltage wherein, output AC signal IO_HPOUTL, IO_HPOUTR are to electro-acoustic element, to convert voice signal output to.
In order further to simplify circuit structure under the prerequisite guaranteeing to eliminate POP sound, the present embodiment is preferably only arranged on voltage clamp circuit in the audio transmission channel being communicated with under switch chip S6001 normality, in the audio transmission channel of the single-ended stereophonic signal MIX_L of transmission, MIX_R as shown in Figure 4, making the voltage of clamping down on of voltage clamp circuit output can be capacitance C6023, C6026 charging in time.So, even if be switched to the moment of other one group of switch passage at switch chip S6001, due to the voltage on capacitance C6023, C6026 with switch after the DC offset voltage of audio signal suitable, therefore, can not produce voltage jump, thereby there will not be POP sound.
Certainly, also can voltage clamp circuit be all set in multichannel voice frequency transmission channel, the present embodiment does not specifically limit this.
Embodiment bis-, shown in Figure 5, the audio system of the 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 difference audio signal, such as AUXOP, AUXON.Because more current in the industry audio frequency amplifier is all difference input form, audio frequency amplifier U2, U3 as shown in Figure 5, if the DC offset voltage of two signals of its differential input end is inconsistent, will make audio frequency amplifier U2, U3 produce POP sound in switch moment.If audio frequency amplifier U2, U3 directly receive conventional difference audio signal AUXOP, AUXON, because the DC offset voltage in difference audio signal AUXOP, AUXON equates, therefore, can in opening or close audio frequency amplifier U2, U3, not produce POP sound.
But for single-ended audio signal, such as MIX_L, MIX_R, need to be made into and transfer to again audio frequency amplifier U2, U3 after differential signal and carry out power amplification processing, and then be driven loud speaker output sound.In order to realize the purpose of design of eliminating POP sound, the present embodiment adopt voltage clamp circuit output clamp down on voltage and single-ended audio signal is made into differential signal, transfer to audio frequency amplifier and carry out power amplifier processing.What wherein, voltage clamp circuit provided clamp down on voltage magnitude should equal the DC offset voltage amplitude of the single-ended audio signal that is made into differential signal with it.As the voltage of clamping down on of the voltage clamp circuit output being formed by divider resistance R6032, R6033 and DC power supply VMSMP in Fig. 5, can be made into differential signal with single-ended right channel audio signal MIX_R, connect 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 the magnitude of voltage of its dividing potential drop Nodes just equal the DC offset voltage of MIX_R signal, so just can eliminate the POP sound of exporting by right channel loudspeaker.In like manner, can utilize the voltage of clamping down on of an other road voltage clamp circuit output to be made into differential signal with it for single-ended left channel audio signal MIX_L, export audio frequency amplifier U3 to and carry out after power amplifier processing, through left channel loudspeaker output sound.Such as the voltage clamp circuit being formed by divider resistance R6034, R6035 and DC power supply VMSMP in Fig. 5, as long as the resistance of configuration divider resistance R6034, R6035, make the DC offset voltage of clamping down on voltage and equal single-ended left channel audio signal MIX_L of its dividing potential drop Nodes output, can avoid left channel loudspeaker output POP sound.In 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 meet the switching output requirement of multipath audio signal, the present embodiment has designed switching circuit in multichannel voice frequency transmission channel, as the switch chip S6003 in Fig. 5, and wherein one group of corresponding connection of differential signal that switch ways NCn is made into single-ended audio signal; Other one group of switch ways NOn connection corresponding to 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 audio frequency processing circuit, such as connecting the GPIO51 mouth of master chip, receive the control signal of master chip output, and then which group differential signal transmission of definite gating processes to audio frequency amplifier U2, U3, to export the audio signal of choosing.
Very little owing to being connected to the capacitance of capacitance C6022, C6018, C6017, C6020 of differential input end of audio frequency amplifier U2, U3, therefore signal lag is very little, in the time of voice-grade channel switch or switching, the impact that generation voltage jump thereon can cause has been taken into account by audio frequency amplifier U2, U3, therefore, need not consider to produce due to the setting of capacitance C6022, C6018, C6017, C6020 the problem of POP sound.
Take mobile phone as example, specifically set forth described POP sound and eliminate the concrete application of circuit in mobile phone circuit below.
Embodiment tri-, shown in Figure 6, along with becoming stronger day by day of cell-phone function, current many high-end mobile phone all possesses complicated audio system, such as supporting the playing functions such as MP3, MP4, FM audio broadcasting, therefore need the output form of various audio signals to consider comprehensively.
As shown in Figure 6, voice signal when mobile phone communication and keypad tone are by being integrated in audio codec CODEC1 in the master chip formal output with difference monophonic signal AUXOP, AUXON and single-ended monophonic signal EAR20; After audio signal in MP3, MP4 file can be processed by audio codec CODEC2, with the formal output of single-ended stereophonic signal HPOUTR, HPOUTL; After can processing by audio codec CODEC3 for FM broadcast, with the formal output of single-ended stereophonic signal FM_OUTR, FM_OUTL.Wherein, the single-ended monophonic signal EAR20 exporting by CODEC1 and the single-ended stereophonic signal of exporting by CODEC2, CODEC3 are eliminated circuit 1 by POP sound and are exported stereophone to, in the time that user is inserted on mobile phone by earphone, by earphone output audio signal.And the difference monophonic signal AUXOP, the AUXON that export by CODEC1 and eliminate circuit 1 by POP sound and switch single-ended stereophonic signal MIX_L, the MIX_R of output, on mobile phone not when plugged earphone, export audio frequency amplifier U to by POP sound elimination circuit 2 and carry out after power amplification processing, drive boombox output audio signal.
Wherein, POP sound elimination circuit 1 can adopt increases the realization of the form design of switch chip S6002 on the basis of Fig. 4 circuit, as shown in Figure 7.After utilizing switch chip S6002 to switch the single-ended stereophonic signal of CODEC2, CODEC3 output, the audio signal (being designated as MIX_L, MIX_R) of output gating is respectively to switch chip S6001 and loud speaker power amplifier.Switch chip S6001 carries out the single-ended monophonic signal EAR20 of audio signal MIX_L, MIX_R and CODEC1 output after gating, to export stereophone output sound to through capacitance C6023, C6026.
Because CODEC internal audio frequency output adopts push-pull output circuit more.The structures shape of push-pull circuit its output voltage probably in about VCC/2, and push-pull circuit is not while working, CODEC output mostly is high impedance status.These characteristics for we provide design according to and guaranteed the portability of this circuit.By the adjustment of supply power voltage, the operation level of three CODEC all can be fixed on to about 2.8V, so just can guarantee that the DC offset voltage amplitude of the audio signal that their export is about 1.4V.Be chosen in the audio transmission channel of transmitting MIX_L, MIX_R signal voltage clamp circuit is set, and make the magnitude of voltage of its dividing potential drop Nodes in 1.4V left and right, can eliminate the POP sound of exporting by earphone.
Because the volume difference of each CODEC output is larger, especially single-ended stereophonic signal FM_OUTR, the FM_OUTL of CODEC# 3 output, the level difference between volumes at different levels is less, and volume entirety is higher compared with other CODEC.For the output volume of balance earphone, the present embodiment in the connection line of capacitance C6023, C6026 and stereophone, connect separately again Liao Yi road resistance R 6038 and R6039, as shown in Figure 6, thereby can make the volume of exporting by CODEC3 agree with people's ear demand, and guarantee the consistency of all CODEC output sound sizes.Meanwhile, 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 form a high pass filter, and the algorithm that its filter 3dB is ordered is f=1/2 π RC.The present embodiment, by increasing resistance R 6038/R6039, has also just reduced f, makes the low-frequency cut-off frequency step-down of audio signal, thereby has improved the supper bass effect of sound.
POP sound is eliminated circuit 2 and can be adopted the circuit structure design shown in Fig. 5 to realize, and the present embodiment no longer repeats at this.
Table 1 has been listed the control truth table of related master chip GPIO mouth in 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 the current earphone connection that whether has, know again the audio signal that need to play which CODEC output, only the state correspondence of controlling above the GPIO mouth using need be come just can easily realize, and not need to wait for time delay.
| GPIO51 | GPIO46 | GPIO47 | ||
| EAR20 exports from earphone | X | 0 | X | |
| HPOUTL/HPOUTR exports from | X | 1 | 0 | |
| FM_OUTR/FM_OUTL exports from | X | 1 | 1 | |
| HPOUTL/HPOUTR exports from |
0 | 1 | 0 | |
| FM_OUTR/FM_OUTL exports from |
0 | 1 | 1 | |
| AUXOP/AUXON exports from loud speaker | 1 | X | X |
Table 1
POP sound of the present invention is eliminated circuit by changing the number of 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 terminal such as mobile phone, palmtop PC.
Certainly; the above is only a kind of preferred implementation of the present invention, it should be pointed out that for those skilled in the art; under the premise without departing from the principles of the invention, any improvements and modifications of making all should be considered as protection scope of the present invention.
Claims (3)
1. the plosive of audio system is eliminated a circuit, comprises audio frequency amplifier and the capacitance of audio frequency processing circuit, electro-acoustic element, reception differential signal; The audio signal of described audio frequency processing circuit output exports capacitance to through audio transmission channel, and after capacitance isolates out the DC offset voltage in audio signal, output AC signal is to electro-acoustic element, to convert voice signal output to; It is characterized in that: in described audio transmission channel, be connected with voltage clamp circuit, 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 transmission of audio signal; Wherein,
Described audio frequency processing circuit is exported a single-ended monophonic signal in road and the single-ended stereophonic signal of multichannel, the single-ended stereophonic signal of multichannel wherein, after a switching circuit carries out passage gating, transfers to respectively loud speaker power amplifier and another switching circuit by audio transmission channel; Described another switching circuit switches between the single-ended stereophonic signal receiving and single-ended monophonic signal, and the single-ended audio signal of output gating is to described capacitance, through capacitance frames connecting with headphone; Described voltage clamp circuit is connected in the audio transmission channel being communicated with under described another switching circuit normality; In the line of described capacitance and earphone, be in series with resistance;
Transfer to the single-ended audio signal of loud speaker power amplifier and the voltage of clamping down on that another voltage clamp circuit provides and be made into differential signal, transfer to the differential signal input of audio frequency amplifier by another group capacitance, undertaken after power amplification processing by audio frequency amplifier, drive loud speaker output sound; The DC offset voltage of clamping down on voltage and equal described single-ended audio signal of described another voltage clamp circuit;
Described capacitance is tantalum electric capacity.
2. the plosive of audio system according to claim 1 is eliminated circuit, it is characterized in that: the divider resistance that includes two series connection in described voltage clamp circuit, described resistance series arm one end connects DC power supply, other end ground connection, its dividing potential drop node is connected in described audio transmission channel, configure the resistance of described divider resistance, make the voltage of its dividing potential drop Nodes equal the DC offset voltage of the audio signal that described audio transmission channel transmits.
3. a mobile communication terminal, is characterized in that: the plosive that includes audio system as claimed in claim 1 or 2 is eliminated circuit.
Priority Applications (1)
| 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 |
Applications Claiming Priority (1)
| 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 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101790122A CN101790122A (en) | 2010-07-28 |
| CN101790122B true CN101790122B (en) | 2014-05-14 |
Family
ID=42533130
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201010109891.6A Expired - Fee Related CN101790122B (en) | 2010-02-06 | 2010-02-06 | Plosive eliminating circuit of audio system and mobile communication terminal |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101790122B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| 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 |
| 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 |
| CN103139689B (en) * | 2011-11-23 | 2015-08-05 | 安凯(广州)微电子技术有限公司 | A kind of apparatus and method eliminating earphone plosion |
| US8947163B2 (en) * | 2012-05-02 | 2015-02-03 | Qualcomm Incorporated | Split capacitors scheme for suppressing overshoot voltage glitches in class D amplifier output stage |
| 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 |
| 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 |
| CN104967946B (en) * | 2015-06-10 | 2018-10-09 | 上海韦尔半导体股份有限公司 | A kind of multi-channel audio processor |
| 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 |
| KR101725761B1 (en) * | 2016-06-28 | 2017-04-11 | 래드손(주) | Audio equipment and audio output port |
| 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 |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN201349199Y (en) * | 2009-01-19 | 2009-11-18 | 深圳市同洲电子股份有限公司 | Amplification circuit |
-
2010
- 2010-02-06 CN CN201010109891.6A patent/CN101790122B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN201349199Y (en) * | 2009-01-19 | 2009-11-18 | 深圳市同洲电子股份有限公司 | Amplification circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101790122A (en) | 2010-07-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101790122B (en) | Plosive eliminating circuit of audio system and mobile communication terminal | |
| CN101232744B (en) | Method and device for multi sound source sharing audio power amplifier | |
| CN104717588A (en) | Low-power-consumption in-ear type active noise reduction earphone and noise reduction method | |
| CN204014027U (en) | A kind of digital audio decoding general headrest with USB interface | |
| CN204014021U (en) | With the earphone of sound-conducting apparatus | |
| CN208675514U (en) | A kind of frequency switch circuit and electronic equipment | |
| CN102387429B (en) | Audio signal switching device and audio signal transmission system | |
| CN104254040B (en) | Mobile communication terminal Audio conversion system | |
| CN108600888A (en) | A kind of noise reduction bluetooth headset | |
| CN204206429U (en) | Audio signal processing | |
| CN106170114A (en) | Control method, device and the audio-frequence player device of a kind of audio frequency output | |
| CN203193848U (en) | Denoising earphone and earphone plug thereof | |
| CN1774143A (en) | Earphone output circuit capable of omitting block capacitor | |
| CN105100999A (en) | Dual impedance earphone | |
| CN202310065U (en) | Audio output device | |
| CN201479354U (en) | Power amplifier muting circuit | |
| CN201207642Y (en) | Wireless noise reducing earphone | |
| CN202103828U (en) | Switching circuit with speaker output being compatible to earphone output and earphone input | |
| CN203151729U (en) | Multifunctional earphone | |
| CN202111843U (en) | Sound for suppressing TDMA noises | |
| CN203563181U (en) | Mobile terminal having KTS sound effect | |
| CN207968840U (en) | A kind of circular audio devices of 3D | |
| CN204948330U (en) | Speaker circuit and mobile terminal | |
| CN201854433U (en) | Mobile phone capable of outputting voice frequency by cooperation | |
| CN205179338U (en) | Headphone structure circuit of compatible multiple cell -phone system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C53 | Correction of patent of invention or patent application | ||
| CB02 | Change of applicant information |
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. |
|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140514 Termination date: 20190206 |