CN104469180B - A kind of audio-video signal switching anti-crosstalk device based on analog multiplexer - Google Patents
A kind of audio-video signal switching anti-crosstalk device based on analog multiplexer Download PDFInfo
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Abstract
The invention discloses a kind of audio-video signal based on analog multiplexer to switch anti-crosstalk device, including：Analog multiplexer, control module, signal biasing module and power supply module；The analog multiplexer difference link control module and signal biasing module；The power supply module connects analog multiplexer and signal biasing module respectively；The overall level of signal is raised so as to avoid low level crosstalk phenomenon by the first predetermined voltage by signal biasing module, the supply voltage that the second predetermined voltage is provided by power supply module avoids high level crosstalk phenomenon, so as to solve the problems, such as occur crosstalk between each other in switching signal, so that the quality of image and sound is high, show that clear and natural is true to nature, sound sounds natural melodized, brings and greatly facilitates.
Description
Technical field
The present invention relates to electronics field, more particularly to a kind of audio-video signal based on analog multiplexer
Switch anti-crosstalk device.
Background technology
As the various broadcasting products such as sound shadow product in the market, game machine, top box of digital machine are more and more, each product
Output audio-video interface be possibly different from, but the audio-video signal of these products is required for being connected to display terminal
On, can just show, therefore signal input port species and the way of each input port to display terminal product it is also proposed that
Certain design requirement, that is to say, that species and way be The more the better.
The semiconducter IC development company of display terminal at present, decoding IC exploitation integrated level more and more higher is driven to display,
Almost for terminal shows product, a highly integrated display driving decoding IC can be fully completed signal audio,
Video decoding, V-CHIP, picture and text, picture scaling, operational control etc. are handled.The display driving decoding of existing chip manufacturer design
IC, function are all substantially close, and the type and quantity to various input channels are all limited.Disappear with various in the market
It is more and more to take sound shadow product, game products etc., being intended to for consumer when in use should not be because of adding one
The new sound shadow equipment of platform, when in use, it is also necessary to first remove the connection signal wire of some former sound shadow equipment, so
It is connected to again afterwards on the signal output port of this new sound shadow equipment.So use and very big not side is brought to user
Just, therefore user is necessarily intended to directly from display terminal signal wire corresponding to one group can be drawn to be connected in new equipment, so that it may
Directly to use.
Product, which does more input interfaces, to be shown to this Terminal Type, is limited to the limitation of driving decoding IC input channel quantity,
That must do before multiple signals input enters a Functional Design out more one.Most of product in the market is logical to inputting
The peripheral expansion in road is all to utilize analog multiplexer（That is Switch IC）To realize handoff functionality, such Switch IC
It is i.e. cheap and general.But existing Switch IC periphery circuit design is unreasonable, and signal is all connected in input channel
When, different degrees of crosstalk occurs between each input signal, has a strong impact on the quality of image and sound.
The concrete reason that analog multiplexer produces crosstalk is as described below.Referring to Fig. 1, the as illustrated, simulation
Multiplexer Switch IC select 1 multiplexer for 4, and input is terminated with 4 tunnel input signals, shown when use according to terminal
The demand shown, it is desirable to which certain is when input signal is strobed all the way, the signal cut of other three tunnels.As shown in figure 1, in the Switch IC
Portion includes 8 FETs, controls 4 to select 1 by two control port signals CON_1 and CON_2, such Switch IC's is interior
Portion is all switched using enhanced FET to do.According to the characteristic of FET, FET has cut-in voltage VT,
And the size of cut-in voltage VT corresponding to the FET of unlike material is also different.Please continue to refer to Fig. 1, to make input
The signal at end does not enter output end, then the FET Q7 in Fig. 1 should be in the conduction state, and Q1 and Q2 will be in
Cut-off state, as long as therefore as CON_1=VEE=GND, CON_2=VDD, the IN signals of input would not be sent to output end.
Conversely if it is desired that certain road input signal enters output end, then Q7 should be just in by state, and Q1, Q2, Q3, Q4,
Q5 should be in the conduction state.The output end of all signals is shared.
Assuming that in 4 select 1 Switch IC, input port is that control terminal CONTROL has gated IN1 letters in IN1-IN4
Number, therefore will have IN1 signal outputs in output end, then IN2, IN3, IN4 signal and output end are off.Therefore
If it is known that to close certain road signal, then Q7 should be in the conduction state, and Q1 and Q2 will be in by state, and
And now CON_1=VEE=GND, CON_2=VDD.Each FET has cut off other signals well in terms of surface analysis,
But when the signal less than GND level occur in other input signals, now just occur N-channel enhancement mode FET Q1's
There is Vgs in thresholding cut-in voltage Vgs>VT situation, so as to cause the signal stream less than VT level to enter output end, it is mixed into
In IN1 signals, this is low level crosstalk phenomenon.Similarly, P-channel enhancement type FET Q2 can also be analyzed to be also possible to lead
It is logical, for example when the input signal on certain road is higher than VDD, it can also find Q2 thresholding cut-in voltage Vgs<VT, so as to also can
Occur entering output end higher than the signal of VDD level, this is high level crosstalk phenomenon.To all string be produced in the case of both the above
Disturb, allow IN1 signals to occur on display terminal abnormal.
Therefore, prior art has yet to be improved and developed.
The content of the invention
The technical problem to be solved in the present invention is, there is provided a kind of audio-video signal switching based on analog multiplexer
Anti-crosstalk device, it is intended to solve existing analog multiplexer and crosstalk is produced when audio-video signal switches so as to influence image
And the problem of sound quality.
The technical proposal for solving the technical problem of the invention is as follows：
A kind of audio-video signal switching anti-crosstalk device based on analog multiplexer, wherein, including：Multipexer is answered
With device, control module, signal biasing module and power supply module；The signal biasing module is by the multipath audio signal of input or regards
Output to analog multiplexer, the Multipexer is answered after voltage in frequency signal per signal all the way raises the first predetermined voltage
Signal output all the way is selected from the multipath audio signal or vision signal with device；The control module control Multipexer is answered
Signal behavior switching is carried out with device；The power supply module is pre- to the analog multiplexer and the offer second of signal biasing module
Determine voltage.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, described first is predetermined
Voltage is more than the cut-in voltage of FET in the analog multiplexer；Second predetermined voltage is more than the audio of input
The maximum peak-to-peak value of signal or vision signal.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, in addition to：For right
The audio frequency and video process chip that audio signal or vision signal are handled；The audio frequency and video process chip connects analog multiplexer
Device.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, the signal biasing
Module includes：It is multiple to be used to corresponding with the multipath audio signal or vision signal of input, Qie Jianggai roads audio signal or regard
The voltage of frequency signal raises the signal bias unit of the first predetermined voltage.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, when the simulation is more
When path multiplexer is video simulation multiplexer, the signal biasing module input is multi-channel video signal；
The signal bias unit includes：The first electrostatic for carrying out electrostatic protection to the vision signal all the way of input is prevented
Protect subelement, the first impedance matching subelement for carrying out impedance matching to the vision signal, for believing the video
Number carry out the first blocking coupling subelement of blocking coupling and for the voltage of the vision signal to be raised into the first predetermined voltage
First biasing subelement；The first electrostatic protection subelement, the first impedance matching subelement, the first blocking coupling subelement
It is sequentially connected with the first biasing subelement；The first biasing subelement connection video simulation multiplexer.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, first electrostatic
Protection subelement includes：First electrostatic protection diode；The first impedance matching subelement includes：First resistor and the first electricity
Hold；The first blocking coupling subelement includes：Second electric capacity；The first biasing subelement includes：Second resistance and the 3rd
Resistance；
The output end of the vision signal is connect by the first electrostatic protection diode, first resistor and the first electric capacity respectively
Ground, also pass through video simulation multiplexer described in the second capacitance connection；The video simulation multiplexer passes through the second electricity
Resistance connection power supply module, is also grounded by 3rd resistor.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, the second resistance
It is identical with the resistance of 3rd resistor.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, when the simulation is more
When path multiplexer is audio frequency simulation multiplexer, the signal biasing module input is multipath audio signal；
The signal bias unit includes：Right channel audio signal for the audio signal all the way to input carries out electrostatic
Second electrostatic protection subelement of protection, the second impedance matching for carrying out impedance matching to the right channel audio signal
Unit, for carrying out the second blocking of blocking coupling to the right channel audio signal couple subelement and for by the right side
The voltage of channel audio signal raises the second biasing subelement of the first predetermined voltage；The second electrostatic protection subelement,
Two impedance matching subelements, the second blocking coupling subelement and the second biasing subelement are sequentially connected；Second biasing is single
Member connection audio frequency simulation multiplexer；
The signal bias unit also includes：Left channel audio signal for the audio signal all the way to input carries out quiet
3rd electrostatic protection subelement of electricity protection, the 3rd impedance matching for carrying out impedance matching to the left channel audio signal
Subelement, for the left channel audio signal carry out blocking coupling the 3rd blocking couple subelement and for will described in
The voltage of left channel audio signal raises the 3rd biasing subelement of the first predetermined voltage；The 3rd electrostatic protection subelement,
3rd impedance matching subelement, the 3rd blocking coupling subelement and the 3rd biasing subelement are sequentially connected；3rd biasing
Unit connects audio frequency simulation multiplexer.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, second electrostatic
Protection subelement includes：Second electrostatic protection diode；The second impedance matching subelement includes：3rd electric capacity, the 4th electricity
Resistance and the 5th resistance；The second blocking coupling subelement includes：4th electric capacity；The second biasing subelement includes：6th
Resistance and the 7th resistance；
The right channel audio signal output end of the audio signal passes through the second electrostatic protection diode and the 3rd electricity respectively
Hold ground connection；The right channel audio signal output end of the audio signal is also passed sequentially through described in the 4th resistance and the 4th capacitance connection
Audio frequency simulation multiplexer, the right channel audio signal output end of the audio signal also pass sequentially through the 4th resistance and the 5th
Resistance eutral grounding；The audio frequency simulation multiplexer connects power supply module by the 6th resistance, also passes through the 7th resistance eutral grounding；
The 3rd electrostatic protection subelement includes：3rd electrostatic protection diode；The 3rd impedance matching subelement
Including：5th electric capacity, the 8th resistance and the 9th resistance；The 3rd blocking coupling subelement includes：6th electric capacity；Described 3rd
Biasing subelement includes：Tenth resistance and the 11st resistance；
The left channel audio signal output end of the audio signal passes through the 3rd electrostatic protection diode and the 5th electricity respectively
Hold ground connection；The left channel audio signal output end of the audio signal is also passed sequentially through described in the 8th resistance and the 6th capacitance connection
Audio frequency simulation multiplexer, the left channel audio signal output end of the audio signal also pass sequentially through the 8th resistance and the 9th
Resistance eutral grounding；The audio frequency simulation multiplexer connects power supply module by the tenth resistance, also passes through the 11st resistance eutral grounding.
The described switching anti-crosstalk device of the audio-video signal based on analog multiplexer, wherein, the 6th resistance
It is identical with the resistance of the 7th resistance；The resistance of tenth resistance and the 11st resistance is identical.
A kind of audio-video signal switching anti-crosstalk device based on analog multiplexer provided by the present invention, effectively
Solve existing analog multiplexer and crosstalk is produced when audio-video signal switches so as to influence image and sound quality
Problem, it is by signal biasing module that the voltage rise first in the multipath audio signal of input or vision signal per signal all the way is pre-
Voltage output is determined to analog multiplexer, and the first predetermined voltage is increased from the plurality of voltages of input by analog multiplexer
Audio signal or vision signal in select all the way signal output to audio frequency and video process chip；The mould is controlled by control module
Intend multiplexer and carry out signal behavior switching；There is provided by power supply module to the analog multiplexer and signal biasing module
Second predetermined voltage；The overall level of signal is raised so as to avoid low level by the first predetermined voltage by signal biasing module
Crosstalk phenomenon, the supply voltage that the second predetermined voltage is provided by power supply module avoids high level crosstalk phenomenon, so as to solve
Occurring the problem of crosstalk between each other in switching signal so that the quality of image and sound is high, and display clear and natural is true to nature,
Sound sounds natural melodized, brings to user and greatly facilitates.
Brief description of the drawings
Fig. 1 is the electrical installation schematic diagram of existing analog multiplexer；
Fig. 2 is that the audio-video signal switching anti-crosstalk device provided by the invention based on analog multiplexer is preferably implemented
The structured flowchart of example；
Fig. 3 is that the audio-video signal of video simulation multiplexer provided by the invention switches anti-crosstalk device application implementation
The circuit diagram of example；
Fig. 4 is that the audio-video signal of audio frequency simulation multiplexer provided by the invention switches anti-crosstalk device application implementation
The circuit diagram of example.
Fig. 5 is the oscillogram of 1KHz standard audio signals.
Fig. 6 is the oscillogram after audio signal biasing.
Embodiment
The present invention provides a kind of audio-video signal switching anti-crosstalk device based on analog multiplexer, to make the present invention
Object, technical solution and advantage it is clearer, clear and definite, the embodiment that develops simultaneously referring to the drawings to the present invention further specifically
It is bright.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not intended to limit the present invention.
The operation principle of the present invention is illustrated first.The crosstalk for understanding analog multiplexer from background technology produces
Reason, it is because road should not open when normal work FET is forced open-minded, causes what should not be inputted
Signal has entered output end, therefore strictly to disconnect the signal that should not be inputted and can not enter output end completely, so as to avoid
The two kinds of cross talk conditions improved above occur.Both crosstalks are done separately below and progressively analyzes and solves.
The reason for first analysis causes crosstalk less than FET threshold voltage VT, i.e. low level crosstalk phenomenon.Due to when certain
Road needs to have in the signal that is strobed when being exported less than VT level signals, causes the enhanced field of the N-channel on other road signals
Effect pipe causes the road signal to be also and then strobed less than the signal of VT level, so as to form crosstalk.Such phenomenon is more normal
See, mainly when Switch Video and audio signal, often occur such crosstalk, the problems such as forming cross-talk and colour contamination.For
Such phenomenon, by carrying out labor to input signal to triode amplification principle and Principle of Signal Transmission, if defeated
Enter the lowest level signal in signal and allow it also above VT, then when switching, the FET being turned off would not
Having an opportunity to be strobed, would not also this problem occurring.Biasing circuit is usually applied in triode amplification principle
Change the quiescent point of signal, allow triode operation in more stable working region.It can also equally use such
Mentality of designing, if AC signal is added on some direct current signal to transmit, then the whole level of input signal will be by
The lifting height of whole DC level, then it is sent to each Switch IC signal input part, and because each input signal is all folded
It is added on direct current signal, as long as appropriate design DC bias circuit, with regard to the minimum level in input signal can be met necessarily
Higher than VT, such low level crosstalk is just avoided that.As for needing to be added on great DC voltage, this is needed according to transmission
Decision is analyzed and calculated to the parameter index of signal and Switch IC power reguirements.
And the high level crosstalk phenomenon for occurring higher than supply voltage VDD level, such crosstalk, which is mainly reflected in, cuts
When changing audio signal, because the audio peak-to-peak value level occurred in the audio signal of input higher than supply voltage VDD is believed
Number, then this level signal will cause P-channel to be turned on automatically, so as to crosstalk occur, just be needed full for such crosstalk
In the case of the certain input signal of foot, circuit design requirements supply voltage VDD necessarily be greater than the audio signal or video letter of input
Number maximum peak-to-peak value, that is, the supply voltage with higher voltage value using feeder ear is just avoided that such high level
Crosstalk.
Referring to Fig. 2, Fig. 2, which is the audio-video signal provided by the invention based on analog multiplexer, switches anti-crosstalk dress
The structured flowchart of preferred embodiment is put, as illustrated, the audio-video signal switching anti-crosstalk based on analog multiplexer
Device includes：Analog multiplexer 100, control module 200, signal biasing module 300 and power supply module 400；The signal
Biasing module 300 is defeated by voltage the first predetermined voltage of rise in the multipath audio signal of input or vision signal per signal all the way
Go out to analog multiplexer 100, the analog multiplexer 100 and selected from the multipath audio signal or vision signal
Signal output all the way；The control module 200 controls analog multiplexer 100 to carry out signal behavior switching；The power supply mould
Block 400 provides the second predetermined voltage to the analog multiplexer 100 and signal biasing module 300.That is, the mould
Intend multiplexer 100 and distinguish link control module 200 and signal biasing module 300；The power supply module 400 connects mould respectively
Intend multiplexer 100 and signal biasing module 300.
Specifically, the analog multiplexer 100 is existing Switch IC, and concrete function is from the more of input
Selected in road audio signal or vision signal all the way signal output be the multiplexer that a kind of multiselect 1 goes out to audio frequency and video process chip.
The control module 200 control analog multiplexer 100 select it is specific certain all the way at input signal final output to audio frequency and video
Chip 500 is managed, audio signal or vision signal are handled by the audio frequency and video process chip 500.The Multipexer
Multiplexer 100 divides for from the selection of the multipath audio signal of input, audio signal is exported to the sound of audio frequency and video process chip 500 all the way
Frequency analog multiplexer, and vision signal is exported to audio frequency and video process chip all the way from the multi-channel video signal selection of input
500 video simulation multiplexer.The analog multiplexer 100, audio frequency simulation multiplexer, video simulation multichannel
Multiplexer, control module 200 and audio frequency and video process chip 500 are prior art, do not do excessive description herein.The signal biasing
Module 300 is by multichannel input signal（IN1、IN2……INn）Voltage integrally raise the first predetermined voltage after, then be input to mould
Intend in multiplexer 100.As shown in Fig. 2 signal biasing module 300 and multipath audio signal or the signal source end of vision signal
（Namely signal output part）Connection, then the first predetermined electricity will be all raised per the voltage of audio signal or vision signal all the way
Pressure, then signal that plurality of voltages is increased to the first predetermined voltage again are sent to analog multiplexer 100.Specifically,
The present invention is exactly to increase a signal biasing module 300 on original analog multiplexer 100 to input per sound all the way
Frequency signal or vision signal carry out boosting processing, that is, raise the first predetermined voltage and then export multichannel input signal to mould
Intend multiplexer 100.So, the low level crosstalk in analog multiplexer 100 as stated in the Background Art can be avoided to show
As.Then the power supply module 400 provides the second predetermined voltage with higher voltage value, can avoid analog multiplexer
High level crosstalk phenomenon in 100 as stated in the Background Art.
Further, the audio-video signal switching anti-crosstalk device based on analog multiplexer, in addition to：With
In the audio frequency and video process chip 500 handled audio signal or vision signal；The audio frequency and video process chip 500 connects mould
Intend multiplexer 100.
Further, the audio-video signal switching anti-crosstalk device based on analog multiplexer, wherein, the signal is inclined
Putting module 300 includes：It is multiple to be used to correspond with the multipath audio signal or vision signal of input and audio signal all the way
Or the voltage of vision signal raises the signal bias unit of the first predetermined voltage.That is, the analog multiplexer 100
Including multiple signals input and 1 tunnel signal output, and the signal biasing module 300 per input signal all the way to first boosting
After processing, then access analog multiplexer 100.Due to that will enter per input signal all the way to analog multiplexer 100
Row boosting is handled, then the circuit inputted per signal all the way is all identical.That is, the signal biasing module 300
Including multiple signal bias units, each signal bias unit corresponds audio or video input signal all the way and carries out rise the
The processing of one predetermined voltage.
Due to being all identical per signal bias unit on the way, will no longer be biased in detail per signal on the way herein
Unit is all described in detail, and just for certain in the multiple signals of input, audio signal or vision signal are described in detail all the way
It is as follows.
In practical application, the analog multiplexer 100 divide for audio frequency simulation multiplexer and video simulation it is more
Path multiplexer.Referring to Fig. 3, when the analog multiplexer 100 is video simulation multiplexer 110, the signal
The input of biasing module 300 is multi-channel video signal；
The signal bias unit includes：The first electrostatic for carrying out electrostatic protection to the vision signal all the way of input is prevented
Protect subelement 311, the first impedance matching subelement 312 for carrying out impedance matching to the vision signal, for described
Vision signal carries out the first blocking coupling subelement 313 of blocking coupling and for by the voltage of vision signal rise the
First biasing subelement 314 of one predetermined voltage；The first electrostatic protection subelement 311, the first impedance matching subelement
312nd, the first blocking coupling subelement 313 314 is connected successively with the first biasing subelement；The first biasing subelement 314 connects
Connect video simulation multiplexer.
Please continue to refer to Fig. 3, further, when input be multi-channel video signal, the analog multiplexer 100 for regarding
During frequency analog multiplexer 110, the first electrostatic protection subelement 311 includes：First electrostatic protection diode ESD1；Institute
Stating the first impedance matching subelement 312 includes：First resistor R1 and the first electric capacity C1；First blocking couples subelement 313
Including：Second electric capacity C2；The first biasing subelement 314 includes：Second resistance R2 and 3rd resistor R3.
The output terminals A V1_IN of the vision signal respectively by the first electrostatic protection diode ESD1, first resistor R1 and
First electric capacity C1 is grounded, and also passes through the second electric capacity C2 connections video simulation multiplexer 110；The video simulation multichannel
Multiplexer 110 is also grounded by second resistance R2 connections power supply module 400 by 3rd resistor R3.Video simulation shown in Fig. 3
Multiplexer 110, i.e. Switch IC select 1 for 4, are merely illustrative, are not limited herein.
Specifically, due to all identical per the signal bias unit circuit all the way in vision signal, therefore for input
Vision signal AV1_IN is described in detail as follows all the way, when vision signal AV1_IN is from signal source end（The signal of vision signal
Output end）When being sent into next, electrostatic protection is carried out by the first electrostatic protection diode ESD1 first, is then using first resistor R1
Impedance matching is carried out to it, the first resistor is preferably 75 Ohmic resistances.After vision signal AV1_IN has been ideally impedance matched,
The AC-amplitudes of vision signal now are 1Vpp, then after the second electric capacity C2 blocking coupling, signal will go into
Switch IC input AV1_VIN.Simultaneously input vision signal AV1_IN and entered by second resistance R2 and 3rd resistor R3
Row bias treatment, the second resistance R2 and 3rd resistor R3 can be chosen according to being actually needed, so as to believe video
Number voltage raise the first predetermined voltage.Preferably, the first predetermined voltage is more than FET in the analog multiplexer
Cut-in voltage, such vision signal for standard, contrast refers to Fig. 1, after biasing circuit is added no matter front end signal
It is when being in maximum level or minimum level, Q1 Vgs is necessarily less than 0V, while Q2 Vgs is also more than 0V always, so as to tight
The generation for inhibiting crosstalk of lattice, it ensure that integrality of signal when switching.
Preferably, in practical application, the second resistance R2 is identical with 3rd resistor R3 resistance, that is, when R2=
During R3（Recommend the resistance of this quasi-resistance in 47K or so）, now the DC offset voltage at AV1_VIN is VDD/2, exchanges video
Signal will be added in VDD/2 DC level, whole video input signals VDD/2 by upward lifting；Combining to preceding
The principle Analysis electric in face of Switch IC, can be obtained, for the vision signal of standard, when adding biasing circuit
No matter front end signal is when being in maximum level or minimum level afterwards, the strict generation for inhibiting crosstalk, ensure that signal
Integrality when switching.First predetermined voltage is not necessarily intended to be fixed as VDD/2, and this can be according to the letter of reality
Number amplitude is set to do appropriate selection, can complete to configure by divider resistance value corresponding to adjustment.It is using VDD/2 herein
For the sake of convenient.
Please continue to refer to Fig. 3, the multi-channel video signal of input, under control terminal CD4052_A, CD4052_B control,
Realize the gating control of signal.Signal bias unit corresponding to being also equipped with the vision signal of other road inputs, herein no longer
It is described in detail.
Further, referring to Fig. 4, when the analog multiplexer 100 is audio frequency simulation multiplexer 120,
The input of signal biasing module 300 is multipath audio signal；
The signal bias unit includes：Right channel audio signal for the audio signal all the way to input carries out electrostatic
Second electrostatic protection subelement 321 of protection, the second impedance for carrying out impedance matching to the right channel audio signal
Subelement 323 and use are coupled with subelement 322, for carrying out the second blocking of blocking coupling to the right channel audio signal
In the second biasing subelement 324 that the voltage of the right channel audio signal is raised to the first predetermined voltage；Second electrostatic
Subelement 321, the second impedance matching subelement 322, the second blocking coupling subelement 323 and second is protected to bias subelement 324
It is sequentially connected；The second biasing subelement 324 connects audio frequency simulation multiplexer 120；
The signal bias unit also includes：Left channel audio signal for the audio signal all the way to input carries out quiet
3rd electrostatic protection subelement 331 of electricity protection, the 3rd impedance for carrying out impedance matching to the left channel audio signal
Coupling subelement 332, for the left channel audio signal carry out blocking coupling the 3rd blocking couple subelement 333 and
For the voltage of the left channel audio signal to be raised to the 3rd biasing subelement 334 of the first predetermined voltage；Described 3rd is quiet
Electricity protection subelement 331, the 3rd impedance matching subelement 332, the 3rd blocking coupling subelement 333 and the 3rd bias subelement
334 are sequentially connected；The 3rd biasing subelement 334 connects audio frequency simulation multiplexer 120.
Please continue to refer to Fig. 4, further, when input multipath audio signal, the analog multiplexer 100 are audio
During analog multiplexer 120, the second electrostatic protection subelement 321 includes：Second electrostatic protection diode ESD2；It is described
Second impedance matching subelement 322 includes：3rd electric capacity C3, the 4th resistance R4 and the 5th resistance R5；The second blocking coupling
Subelement 323 includes：4th electric capacity C4；The second biasing subelement 324 includes：6th resistance R6 and the 7th resistance R7.
The right channel audio signal output terminals A V1_R of the audio signal passes through the second electrostatic protection diode ESD2 respectively
It is grounded with the 3rd electric capacity C3；The right channel audio signal AV1_R output ends of the audio signal also pass sequentially through the 4th resistance R4
The AV1_RIN ends of the audio frequency simulation multiplexer 120, the right audio channel of the audio signal are connected with the 4th electric capacity C4
Signal output part AV1_R also passes sequentially through the 4th resistance R4 and the 5th resistance R5 ground connection；The audio frequency simulation multiplexer 120
AV1_RIN ends by the 6th resistance R6 connections power supply module 400, also pass through the 7th resistance R7 ground connection；
The 3rd electrostatic protection subelement 331 includes：3rd electrostatic protection diode ESD3；3rd impedance matching
Subelement 332 includes：5th electric capacity C5, the 8th resistance R8 and the 9th resistance R9；The 3rd blocking coupling subelement 333 wraps
Include：6th electric capacity C6；The 3rd biasing subelement 334 includes：Tenth resistance R10 and the 11st resistance R11；
The left channel audio signal output terminals A V1_L of the audio signal passes through the 3rd electrostatic protection diode ESD3 respectively
It is grounded with the 5th electric capacity C5；The left channel audio signal output terminals A V1_L of the audio signal also passes sequentially through the 8th resistance R8
The AV1_LIN ends of the audio frequency simulation multiplexer 120, the left audio of the audio signal are connected with the 6th electric capacity C6
Signal output part AV1_L also passes sequentially through the 8th resistance R8 and the 9th resistance R9 ground connection；The audio frequency simulation multiplexer 120
By the tenth resistance R10 connections power supply module 400, also it is grounded by the 11st resistance R11.Audio frequency simulation multichannel shown in Fig. 4
Multiplexer 120, i.e. Switch IC select 1 for 4, under control terminal CD4052_A, CD4052_B control, realize the gating of signal
Control, is merely illustrative, is not limited herein.
Specifically, in audio frequency simulation multiplexer, the multipath audio signal and Multipexer that are connected to input are answered
It is similar with the circuit diagram of above-mentioned connection multi-channel video signal with the circuit diagram of the signal bias unit between device.Because audio is believed
Number include left channel audio signal and right channel audio signal.Therefore left channel audio signal is included per the input of audio signal all the way
Input and right channel audio signal input.The signal biased electrical that left channel audio signal inputs and right channel audio signal inputs
Road is all identical.Because audio frequency simulation multiplexer includes multipath audio signal input, input and connect per audio signal all the way
Signal bias unit it is also identical, do not repeat herein.
Specifically, when right channel audio signal AV1_R is from signal source end（The signal output part of audio signal）It is sent into and
When, first by the second electrostatic protection diode ESD2 carry out electrostatic protection, then using the 3rd electric capacity C3, the 4th resistance R4 and
5th resistance R5, after carrying out impedance matching to it.Right channel audio signal AV1_R couples by the 4th electric capacity C4 blocking again
Afterwards, signal will go into audio frequency simulation multiplexer 120（Switch IC）Input AV1_RIN.Right audio channel simultaneously
Signal AV1_R is simultaneously biased by the 6th resistance R6 and the 7th resistance R7, and the 6th resistance R6 and the 7th resistance R7 can bases
It is actually needed and is chosen, so that the voltage of audio signal is raised into the first predetermined voltage.Preferably, the first predetermined voltage
More than the cut-in voltage of FET in the analog multiplexer, the so audio signal for standard, contrast is refering to figure
1, when no matter front end signal is to be in maximum level or minimum level after adding biasing circuit, Q1 Vgs is necessarily less than
0V, while Q2 Vgs is also more than 0V always, so as to the strict generation for inhibiting crosstalk, ensure that signal when switching
Integrality.Similarly, the processing for left channel audio signal AV1_L is identical, and here is omitted.So, can be by entirely
Input audio signal first predetermined voltage by upward lifting, therefore after Switch IC are entered, also will not when switching over
Occur cross-interference issue again, solve crosstalk of the audio signal under low level.
Also referring to Fig. 5 and Fig. 6, in practical application, the resistance of the 6th resistance R6 and the 7th resistance R7 is identical；
The resistance of the tenth resistance R10 and the 11st resistance R11 is identical.Recommend the resistance of this quasi-resistance in 47K or so.Now AV1_
R DC offset voltage is VDD/2, and exchange vision signal will be added in VDD/2 DC level, whole audio input letter
The VDD/2 number by upward lifting；Combining to principle Analysis above electric to Switch IC, can obtain, for mark
Accurate audio signal, when no matter front end signal is to be in maximum level or minimum level after adding biasing circuit, strictly
The generation for inhibiting crosstalk, ensure that signal switching when integrality.First predetermined voltage is not necessarily fixed
For VDD/2, this can do appropriate selection according to the signal amplitude of reality and set, and pass through divider resistance value corresponding to adjustment
It can complete to configure.For the sake of being convenient using VDD/2 herein.
For the full color vision signal of phenomenon, at present standard that crosstalk is produced higher than VDD（The ohms impedance match of band 75
When）Peak-to-peak value be 1Vpp：Synchronizing signal amplitude is -0.3V, luminance signal amplitude 0.7V.Nonstandard vision signal（The Europe of band 75
During nurse impedance matching）：Industry only considers that maximum, just now can be by the decoding of rear end within no more than the 2 of standard signal times at present
IC automatic identifications and normal decoding and display.The audio signal of standard（During bringing onto load 10K）：The peak-to-peak value that frequency is 1KHz is
0.5Vpp.Off-gauge audio signal（Not during bringing onto load）：When frequency is 1KHz, amplitude maximum can arrive how many, from the market
Audio demodulator, it is up to 12Vpp, but the audio product that market is too many, such as the playback equipment such as DVD, computer inherently may be used
To adjust the size of audio, rock music etc. particularly is being played, the moment peak-to-peak value of output is just bigger, therefore for rear end
Display terminal decoding products, most of terminal show that the audio input of product only needs to consider that design is no more than in amplitude peak
10Vpp, output audio distortion is in ± 10%, that is, 10V.In other words, as long as the second predetermined voltage is more than the sound of input
When frequency signal or the maximum peak-to-peak value, i.e. 10V of vision signal, high level crosstalk can be avoided.
And liquid crystal terminal shows that the power supply of product is mainly provided by large power supply plate at present, there is provided voltage it is main
For:5V_STB (standby switches control voltage, is mainly supplied to control module use), and 5V/12V/24V (just can after normal boot-strap
The operating voltage of offer, the power supply for being mainly supplied to other to need to need in the element of meeting work after powering).
Reason typically can all provide 5V in electric power system, tri- kinds of dc sources of 12V, 24V, therefore according to different Switch
The amplitude peak of requirements and input signal of the IC to operating voltage, one suitable operating voltage can of design avoid high level
Crosstalk, switch IC as CD4052B is simulated, the maximum voltage that VDD is supported is 18V, so if doing audio frequency and video switching with this IC
When, fully meet the situation that audio signal is no more than 10Vpp in maximum peak-to-peak value.That is power supply module 400 is only needed to carry
The second predetermined voltage supplied, which is more than 10V, can avoid high level crosstalk.
In summary, a kind of audio-video signal switching anti-crosstalk dress based on analog multiplexer provided by the invention
Put, including：Analog multiplexer, control module, signal biasing module and power supply module；The signal biasing module will input
Multipath audio signal or vision signal in voltage per signal all the way raise the first predetermined voltage and export to analog multiplexer
Device, in multipath audio signal or vision signal that the analog multiplexer increases the first predetermined voltage from the voltage of input
Select signal output all the way；The control module control analog multiplexer carries out signal behavior switching；The power supply module
The second predetermined voltage is provided to the analog multiplexer and signal biasing module；By signal biasing module by the whole of signal
Body level raises the first predetermined voltage so as to avoid low level crosstalk phenomenon, and the second predetermined voltage is provided by power supply module
Supply voltage avoids high level crosstalk phenomenon, so as to solve the problems, such as occur crosstalk between each other in switching signal, makes
Image and sound quality it is high, display clear and natural is true to nature, and sound sounds natural melodized, is brought significantly to user
Convenience.Anti-crosstalk device, Switch IC are switched using the audio-video signal provided by the invention based on analog multiplexer
When carrying out signal hand-off process, will not occur the phenomenon of adjacent signal cross-talk again, so as to ensure that the integrality of signal transmission.
Preferably, former AC signal is loaded into stable VDD/2 DC level, so as to improve the transmission of AC signal
Ability and antijamming capability.
It should be appreciated that the application of the present invention is not limited to above-mentioned citing, for those of ordinary skills, can
To be improved or converted according to the above description, all these modifications and variations should all belong to the guarantor of appended claims of the present invention
Protect scope.
Claims (9)
- A kind of 1. audio-video signal switching anti-crosstalk device based on analog multiplexer, it is characterised in that including：Simulation is more Path multiplexer, control module, signal biasing module and power supply module；The signal biasing module is by the multipath audio signal of input Or output is more to analog multiplexer, the simulation after voltage the first predetermined voltage of rise in vision signal per signal all the way Path multiplexer selects signal output all the way from the multipath audio signal or vision signal；The control module control simulation is more Path multiplexer carries out signal behavior switching；The power supply module provides the to the analog multiplexer and signal biasing module Two predetermined voltages；First predetermined voltage is more than the cut-in voltage of FET in the analog multiplexer；Described second predetermined electricity Pressure is more than the audio signal of input or the maximum peak-to-peak value of vision signal；Raise the first predetermined voltage and then export multichannel input signal to analog multiplexer, avoid Multipexer from answering Low level crosstalk is produced with device.
- 2. the audio-video signal switching anti-crosstalk device according to claim 1 based on analog multiplexer, its feature It is, in addition to：For the audio frequency and video process chip handled audio signal or vision signal；The audio frequency and video handle core Piece connects analog multiplexer.
- 3. the audio-video signal switching anti-crosstalk device according to claim 1 based on analog multiplexer, its feature It is, the signal biasing module includes：It is multiple to be used to correspond and incite somebody to action with the multipath audio signal or vision signal of input The voltage of audio signal or vision signal raises the signal bias unit of the first predetermined voltage all the way.
- 4. the audio-video signal switching anti-crosstalk device according to claim 3 based on analog multiplexer, its feature It is, when the analog multiplexer is video simulation multiplexer, the signal biasing module input regards for multichannel Frequency signal；The signal bias unit includes：For carrying out the first electrostatic protection of electrostatic protection to the vision signal all the way of input Unit, for the vision signal carry out impedance matching the first impedance matching subelement, for entering to the vision signal The first blocking coupling subelement of row blocking coupling and for the voltage of the vision signal to be raised into the of the first predetermined voltage One biasing subelement；The first electrostatic protection subelement, the first impedance matching subelement, the first blocking coupling subelement and the One biasing subelement is sequentially connected；The first biasing subelement connection video simulation multiplexer.
- 5. the audio-video signal switching anti-crosstalk device according to claim 4 based on analog multiplexer, its feature It is, the first electrostatic protection subelement includes：First electrostatic protection diode；The first impedance matching subelement bag Include：First resistor and the first electric capacity；The first blocking coupling subelement includes：Second electric capacity；The first biasing subelement Including：Second resistance and 3rd resistor；The output end of the vision signal by the first electrostatic protection diode, first resistor and the first capacity earth, is gone back respectively Pass through video simulation multiplexer described in the second capacitance connection；The video simulation multiplexer is connected by second resistance Power supply module, also it is grounded by 3rd resistor.
- 6. the audio-video signal switching anti-crosstalk device according to claim 5 based on analog multiplexer, its feature It is, the second resistance is identical with the resistance of 3rd resistor.
- 7. the audio-video signal switching anti-crosstalk device according to claim 3 based on analog multiplexer, its feature It is, when the analog multiplexer is audio frequency simulation multiplexer, the signal biasing module input is multichannel sound Frequency signal；The signal bias unit includes：Right channel audio signal for the audio signal all the way to input carries out electrostatic protection The second electrostatic protection subelement, single for carrying out the second impedance matching of impedance matching to the right channel audio signal Member, for carrying out the second blocking of blocking coupling to the right channel audio signal couple subelement and for by the right sound The voltage of audio channel signal raises the second biasing subelement of the first predetermined voltage；The second electrostatic protection subelement, second Impedance matching subelement, the second blocking coupling subelement and the second biasing subelement are sequentially connected；The second biasing subelement Connect audio frequency simulation multiplexer；The signal bias unit also includes：Left channel audio signal for the audio signal all the way to input, which carries out electrostatic, to be prevented 3rd electrostatic protection subelement of shield, the 3rd impedance matching son list for carrying out impedance matching to the left channel audio signal Member, for carrying out the 3rd blocking of blocking coupling to the left channel audio signal couple subelement and for by the left sound The voltage of audio channel signal raises the 3rd biasing subelement of the first predetermined voltage；The 3rd electrostatic protection subelement, the 3rd Impedance matching subelement, the 3rd blocking coupling subelement and the 3rd biasing subelement are sequentially connected；The 3rd biasing subelement Connect audio frequency simulation multiplexer.
- 8. the audio-video signal switching anti-crosstalk device according to claim 7 based on analog multiplexer, its feature It is, the second electrostatic protection subelement includes：Second electrostatic protection diode；The second impedance matching subelement bag Include：3rd electric capacity, the 4th resistance and the 5th resistance；The second blocking coupling subelement includes：4th electric capacity；Described second is inclined Putting subelement includes：6th resistance and the 7th resistance；The right channel audio signal output end of the audio signal is connect by the second electrostatic protection diode and the 3rd electric capacity respectively Ground；The right channel audio signal output end of the audio signal also passes sequentially through audio described in the 4th resistance and the 4th capacitance connection Analog multiplexer, the right channel audio signal output end of the audio signal also pass sequentially through the 4th resistance and the 5th resistance Ground connection；The audio frequency simulation multiplexer connects power supply module by the 6th resistance, also passes through the 7th resistance eutral grounding；The 3rd electrostatic protection subelement includes：3rd electrostatic protection diode；The 3rd impedance matching subelement includes： 5th electric capacity, the 8th resistance and the 9th resistance；The 3rd blocking coupling subelement includes：6th electric capacity；3rd biasing Subelement includes：Tenth resistance and the 11st resistance；The left channel audio signal output end of the audio signal is connect by the 3rd electrostatic protection diode and the 5th electric capacity respectively Ground；The left channel audio signal output end of the audio signal also passes sequentially through audio described in the 8th resistance and the 6th capacitance connection Analog multiplexer, the left channel audio signal output end of the audio signal also pass sequentially through the 8th resistance and the 9th resistance Ground connection；The audio frequency simulation multiplexer connects power supply module by the tenth resistance, also passes through the 11st resistance eutral grounding.
- 9. the audio-video signal switching anti-crosstalk device according to claim 8 based on analog multiplexer, its feature It is, the resistance of the 6th resistance and the 7th resistance is identical；The resistance of tenth resistance and the 11st resistance is identical.
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| WO2020068710A1 (en) * | 2018-09-24 | 2020-04-02 | Molex, Llc | A system for monitoring a thickness of one or more assets using an ultrasonic measurement system, a multiplexer switch module and a two-conductor connection, and a method of performing the same |
| US11855610B1 (en) | 2020-08-27 | 2023-12-26 | Rockwell Collins, Inc. | Broadband data multiplexer |
| CN116709113B (en) * | 2022-12-21 | 2024-05-24 | 荣耀终端有限公司 | Audio circuit, control method thereof, electronic equipment and audio system |
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| CN2814833Y (en) * | 2005-09-02 | 2006-09-06 | 海信集团有限公司 | TV set with analog on-off circuit |
| CN101437108A (en) * | 2007-11-16 | 2009-05-20 | 深圳Tcl新技术有限公司 | Television set |
| CN201378852Y (en) * | 2009-04-23 | 2010-01-06 | 青岛海信电器股份有限公司 | Audio output circuit and television provided therewith |
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| US6900848B2 (en) * | 2000-05-01 | 2005-05-31 | Thomson Licensing S.A. | Crosstalk reduction in a video signal selector |
| US20020034311A1 (en) * | 2000-09-19 | 2002-03-21 | Kotyuk Joseph D. | Modular multiple channel audio signal conditioning interface |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2814833Y (en) * | 2005-09-02 | 2006-09-06 | 海信集团有限公司 | TV set with analog on-off circuit |
| CN101437108A (en) * | 2007-11-16 | 2009-05-20 | 深圳Tcl新技术有限公司 | Television set |
| CN201378852Y (en) * | 2009-04-23 | 2010-01-06 | 青岛海信电器股份有限公司 | Audio output circuit and television provided therewith |
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