CN106878872A - A kind of peripheral circuit for eliminating noise signal - Google Patents
A kind of peripheral circuit for eliminating noise signal Download PDFInfo
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- CN106878872A CN106878872A CN201710244157.2A CN201710244157A CN106878872A CN 106878872 A CN106878872 A CN 106878872A CN 201710244157 A CN201710244157 A CN 201710244157A CN 106878872 A CN106878872 A CN 106878872A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2430/00—Signal processing covered by H04R, not provided for in its groups
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Abstract
The embodiment of the invention discloses a kind of peripheral circuit for eliminating noise signal, for eliminating the circuit system being connected with audio-frequency load during upper electricity or power-off, the noise signal in the audio signal of output, the peripheral circuit includes：Main control chip, also includes：Drive module, is connected between main control chip and audio-frequency load, for being converted by impedance, strengthens the carrying load ability of audio signal；Control module, is connected between main control chip and Jing Yin module, for producing control level signal during upper electricity or power-off in circuit system；The Jing Yin module is used to, according to control level signal, eliminate the noise signal in audio signal.By using above-mentioned technical proposal, eliminate electronic equipment it is upper electricity and/or power-off during, the noise in audio signal.Also may be such that the output performance of audio signal is more stablized simultaneously, on the basis of headset output interface standard is met, relative to earphone drive circuit of the prior art, reached the effect of reduces cost.
Description
Technical field
The present embodiments relate to electronic device field, more particularly to a kind of peripheral circuit for eliminating noise signal.
Background technology
With the development and the progress of science and technology of society, computer (Computer), communication (Communication) and consumption
Electronics (Consumer Electronics), abbreviation 3C electronic products quickly grow, and win more and more consumers'
Like.And earpiece audio output function, have become most audio/video consumer electronic products (such as flat panel TV, desk-top
Machine, panel computer and mobile phone etc.) standard configuration.Design currently for earphone output circuit is primarily present the following two kinds feelings
Condition：
1st, audio signal amplification module is carried inside the system level chip (System-on-a-Chip, SOC) of electronic equipment,
The driving force of input/output (input/output, IO) interface of signal is stronger, can directly drive earphone load.
2nd, the SOC inside no audio signal amplification module of electronic equipment, its I/O interface impedance is high, and driving force is very weak, needs
Wanting additional power amplifier could drive earphone normally to export.
But, all there is its respective defect in above-mentioned two situations, i.e.,：
Load can be directly driven for situation 1, SOC, but, such SOC is more rare, the mistake of earpiece audio output signal
It is very also more serious, and the amplitude and signal to noise ratio of earpiece audio output signal by SOC, performance is limited in itself, combination property is not
The output effect specified in standard criterion can be fully achieved.Opened and/or shutdown period in electronic equipment, can there is obvious ' Pi
' noise.
For situation 2, additional power amplifier drive earphone, can reach substantially in standard criterion specify output effect, but by
Different in SOC model, can also there is certain ' crack ' and make an uproar in the earphone of some producers during system electrification and/or power-off
Sound, also has the SOC control effects of some producers preferably certainly, but price is of a relatively high, and the peripheral circuit of SOC is also more
Complexity, this will cause that the hardware manufacturing cost of electronic equipment increases.
The content of the invention
To solve Related Technical Issues, the present invention provides a kind of peripheral circuit for eliminating noise signal, by master control core
Piece inside no audio signal amplifying unit on the basis of additional design circuit, solve electronic equipment it is upper electricity or power-off during,
The problem of ' crack ' noise in the audio signal of earphone output.
To achieve the above object, the embodiment of the present invention is adopted the following technical scheme that：
In a first aspect, a kind of peripheral circuit for eliminating noise signal is the embodiment of the invention provides, for elimination and audio
The connected circuit system of load during upper electricity or power-off, the noise signal in the audio signal of output, the peripheral circuit bag
Main control chip is included, the peripheral circuit also includes：
Drive module, is connected between the main control chip and the audio-frequency load, for being converted by impedance, strengthens sound
The carrying load ability of frequency signal；
Jing Yin module, the output end of the Jing Yin module is connected with the drive module；
Control module, is connected between the main control chip and the Jing Yin module, in system electrification or turnoff time
Between produce control level signal；
The Jing Yin module is used for, and according to the control level signal, eliminates the noise signal in the audio signal.
A kind of peripheral circuit is the embodiment of the invention provides, for eliminating the circuit system being connected with audio-frequency load in upper electricity
Or power-off during, the noise signal in the audio signal of output, the peripheral circuit include main control chip, also including drive module,
Control module and Jing Yin module.In the technical program, drive module is connected between main control chip and audio-frequency load, for leading to
Impedance conversion is crossed, strengthens the carrying load ability of audio signal.Load is driven by using drive module, is solved existing
In technology, because SOC direct drives are as caused by earphone even load, the amplitude (signal of the audio signal being input in earphone
Distortion) and " crack " noise the problems such as.Control module is connected between the main control chip and the Jing Yin module, for
Control level signal, the control level signal is produced to trigger the Jing Yin module in circuit system during system electrification or power-off
Worked during electricity or power-off.The output end of Jing Yin module is connected with the earphone drive module, for according to control level signal,
Silence processing is carried out to audio signal, is believed with the noise in the audio signal that is exported during eliminating in circuit system electricity or power-off
Number.Technical scheme provided in an embodiment of the present invention, employs the additional work(being made up of drive module, Jing Yin module and control module
Discharge road to drive earphone, during system electrification or power-off, control module produces the high level of a period of time (such as 2~3 seconds)
Signal, is acted with triggering Jing Yin module, not only eliminate during system electrification or power-off export audio signal in
Noise signal, while also may be such that the output performance of audio signal is more stablized, is meeting the basis of headset output interface standard
On, relative to earphone drive circuit of the prior art, reach the technique effect of reduces cost.
Brief description of the drawings
Technical scheme in order to illustrate more clearly the embodiments of the present invention, institute in being described to the embodiment of the present invention below
The accompanying drawing for needing to use is briefly described, it should be apparent that, drawings in the following description are only some implementations of the invention
Example, for those of ordinary skill in the art, on the premise of not paying creative work, can also implement according to the present invention
The content and these accompanying drawings of example obtain other accompanying drawings.
Fig. 1 is a kind of structural representation of the peripheral circuit of elimination noise signal that the embodiment of the present invention one is provided；
Fig. 2 is the earphone peripheral circuit schematic diagram that a kind of two-channel that the embodiment of the present invention two is provided eliminates noise；
Fig. 3 is a kind of preferred single channel drive module schematic diagram that the embodiment of the present invention two is provided；
Fig. 4 is a kind of control circuit diagram that the embodiment of the present invention two is provided；
Fig. 5 is a kind of monophonic mute circuit schematic diagram that the embodiment of the present invention two is provided；
Fig. 6 is that the present invention implements a kind of two single channel earphone drive circuit figures with mute circuit for providing.
Specific embodiment
For make present invention solves the technical problem that, the technical scheme that uses and the technique effect that reaches it is clearer, below
The technical scheme of the embodiment of the present invention will be described in further detail with reference to accompanying drawing, it is clear that described embodiment is only
It is a part of embodiment of the invention, rather than whole embodiments.Based on the embodiment in the present invention, those skilled in the art exist
The every other embodiment obtained under the premise of creative work is not made, the scope of protection of the invention is belonged to.
Embodiment one
Fig. 1 is a kind of structural representation of the peripheral circuit of elimination noise signal that the embodiment of the present invention one is provided, the electricity
Road can be integrated into such as flat panel TV electronic equipment for possessing main control chip, set for eliminating the electronics being connected with audio-frequency load
It is standby during upper electricity or power-off, the noise signal in the audio signal of output, while can also eliminate electronic equipment standby or open
Noise signal in the audio signal exported during machine.As shown in figure 1, the circuit is specifically included：Main control chip 100, driving mould
Block 110, control module 120 and Jing Yin module 130.
Wherein, drive module 110, are connected between main control chip 100 and audio-frequency load, for being converted by impedance, increase
The carrying load ability of strong audio signal；Control module 120, is connected between main control chip 100 and Jing Yin module 130, for
On electronic equipment control level signal is produced during electricity or power-off；Jing Yin module 130, its output end is connected with drive module 110,
Output for controlling the audio signal according to control level signal, during eliminating electric on electronic equipment or power-off, audio letter
Noise signal in number.
Exemplary, audio-frequency load is preferably earphone.
It is exemplary, main control chip 100 in the technical program as audio signal output I/O interface, for exporting sound
Frequency signal (being AMP-INL and AMP-INR in Fig. 1), the impedance of its output port is 1K Ω, and main control chip exports electricity in zero load
The virtual value of signal is pressed to be 1V to the maximum.And in general, the impedance of earphone is 16 Ω -64 Ω.Specifically, most of consumption
The earphone impedance of electronic product is 32 Ω, wherein, the earphone interface of flat panel TV is also substantially according to the standard of 32 Ω impedances
Design；Also, flat panel TV is in the case of bringing onto load, the requirement of the virtual value of the amplitude of output voltage signal for 300~
500mV.By above-mentioned analysis：Because the impedance of main control chip I/O interface is higher, accordingly, it would be desirable to additionally add external driving
Circuit can be only achieved the basic demand of earphone output amplitude.And using drive module as being led in technical scheme
The main circuit of chip I/O interface impedance conversion.
Exemplary, most of electronic equipment (hereinafter referred to as system) is standby or open in upper electricity or power-off on the market at present
During machine, can be produced in the audio of connected earphone output " crack " noise.And the earphone of the present embodiment offer is provided
In upper electricity or power-off, standby or start, control module 120 will produce one fixed width to the electronic equipment (system) of peripheral circuit
High-level control signal enables network MUTE_EN, controls Jing Yin module 130 to act on by the high-level control signal, and then disappear
Except electronic equipment it is upper electricity or power-off, it is standby or start during by earphone export audio in generation " crack " noise.
A kind of peripheral circuit for eliminating noise signal is the embodiment of the invention provides, the circuit includes main control chip, also wraps
Include drive module, control module and Jing Yin module.In the technical program, drive module is connected to the main control chip and sound
Between frequency is loaded, for being converted by impedance, strengthen the carrying load ability of audio signal.By using drive module to load into
Row drives, it is possible to resolve in the prior art, is loaded because SOC directly drives, the caused audio signal being input in earphone
Amplitude and " crack " noise the problems such as.Control module, is connected between the main control chip and the Jing Yin module, for
Control level signal is produced during system electrification and/or power-off, to control the Jing Yin module to work；The Jing Yin module it is defeated
Go out end to be connected with the earphone drive module, the output for controlling the audio signal according to the control level signal disappears
During except system electrification or power-off, the noise in the audio signal.Technical scheme provided in an embodiment of the present invention, employs outer
Plus power amplifier (drive module, Jing Yin module and control module) drives earphone, during system electrification or power-off, mould is controlled
Block produces the high level signal of a period of time to control Jing Yin module to be acted, and eliminates during system electrification or power-off, sound
Noise in frequency signal.Also may be such that the output performance of audio signal is more stablized simultaneously, meeting headset output interface standard
On the basis of, relative to earphone drive circuit of the prior art, reach the effect of reduces cost.
Embodiment two
Fig. 2 is the earphone peripheral circuit schematic diagram that a kind of two-channel that the embodiment of the present invention two is provided eliminates noise, this reality
Apply example to be refined on the basis of above-described embodiment, as shown in Fig. 2 the earphone peripheral circuit includes main control chip 200, drives
Dynamic model block 210, control module 220 and Jing Yin module 230.Separately below in the operation principle and modules of modules
The selection of different parameters of operating part is specifically described：
First, drive module 210 is specifically described：
Exemplary, Fig. 3 is a kind of preferred single channel drive module schematic diagram that the embodiment of the present invention two is provided.Such as Fig. 3
Shown, drive module 210 includes emitter follower circuit 211, filter circuit 212.Wherein, emitter follower circuit 211, connection
Between main control chip 200 and load RL, the output impedance for reducing main control chip strengthens the bringing onto load energy of audio signal
Power；Filter circuit 212, is connected between the colelctor electrode of emitter follower 211 and ground, and making an uproar for power end is coupled to for reducing
Sound.Specific explanations are carried out to emitter follower circuit 211 and filter circuit 212 separately below：
1st, emitter follower circuit 211
Before being illustrated to emitter follower circuit 211, the selection first to the supply voltage in this programme is said
It is bright：Power supply in this programme is preferably 5V power supplys, or 3.3V.The power supply is by low pressure difference linear voltage regulator (low
Dropout regulator, LDO) generation, and unswitched power (DC-DC generations).This be because the power supply noise of LDO is smaller,
Therefore it is also smaller on earphone output influence.According to Switching Power Supply, because the switching frequency noise of Switching Power Supply is larger, therefore,
Audio signal influence on earphone output is also larger.
Next, the characteristics of to emitter follower circuit and its including component be described in detail：
The characteristics of emitter follower circuit 211 is：(1) input impedance is high, low (the ideally output impedance of output impedance
For 0), and do not influenceed by load circuit；(2) voltage amplification factor is approximately 1, i.e. by being exported after emitter follower circuit
Audio signal voltage it is identical with the voltage of the audio signal of emitter follower input circuit, and output audio signal frequency
Characteristic is preferable.Based on These characteristics, this programme is by using emitter follower circuit as the drive circuit of earphone, it is possible to decrease main
The output impedance of chip I/O interface is controlled, strengthens the carrying load ability of audio signal.
Exemplary, the model of the transistor in emitter follower circuit is preferably KMBT3904.Because：According to ear
The design specification of machine peripheral circuit, load current maximum is 18.75mA (Ω of 600mA ÷ 32).Output is caused when load is increased
When electric current increases, if drive circuit scarce capacity, the audio signal of output will distortion (the minus side general of such as signal output waveform
It is truncated), so triode emission electrode current IE≈ 50mA, VCBOAnd VCEOMaximum rating to reach more than 5V, and frequency
Bandwidth will meet 20Hz:20KHz.Because the transistor of model KMBT3904 can meet above-mentioned requirements, therefore, emitter following
The model of the transistor in device circuit is preferably KMBT3904.
As shown in figure 3, emitter follower circuit 211 includes：First electric capacity C1, the second electric capacity C2, first resistor R1 and
Two resistance R2.
Wherein, the first electric capacity C1 is connected between the base stage of main control chip 200 and emitter follower circuit 211, for cutting
DC voltage in the audio signal of disconnected input.Second electric capacity C2, is connected to emitter stage and the load of emitter follower circuit 211
Between RL, for completely cutting off direct current, load RL is given by AC audio signal output；After second resistance R2 and first resistor R1 series connection
Circuit, is connected to the first power supply (being 5V in figure) and ground between, for being divided the audio signal that main control chip 200 is exported
Pressure.Specifically, emitter follower circuit 211 also includes that emitter resistance R9, emitter resistance R9 are connected to emitter following electricity
Between the emitter stage and ground on road.
Specifically, the work separately below to the first electric capacity C1, the second electric capacity C2, first resistor R1 and second resistance R2 is former
Reason and its parameter selection are described in detail：
(1) first electric capacity C1 and the second electric capacity C2
C1 is the coupled capacitor of input audio signal, the DC voltage the purpose is to cut off input, with biasing circuit
Resistance (R1 and R2) forms CR high-pass filters.Now,Here it is excellent
Select C1=10 μ F.C2 is the coupled capacitor of output signal, and its purpose is also turned off the DC voltage in the audio signal of its output,
CR high-pass filters are formed with the Ω load resistances of earphone 32, computational methods ibid, are computed C2=220 μ F.
(2) first resistor R1 and second resistance R2
Exemplary, emitter follower circuit 211 is by bias voltage VBThe midpoint of supply voltage (5V) and GND is set in,
That is VB=2.5V.Emitter current IE≈50mA.Voltage V under triode DC operation between base stage and emitter stageBE=0.6V,
Now,According to resistance E24 series, emitter resistance R9 is excellent in this programme
Elect 39 Ω as.Because emitter current is larger (50mA), and KMBT3904 hFE (common emitter low frequency small-signal output exchanges
Short circuit current amplification fact) minimum value be 100, maximum is 300, therefore, hFE is preferably 200 in this programme.Now, base
Electrode current IB=500mA ÷ 200=0.25mA.So base current be can not ignore.
Due to the presence of base current, the biasing resistor R2 of base stage can just meet base voltage V when being more than R1B=2.5V
Requirement.The input impedance for needing to consider this emitter follower circuit simultaneously is R1//R2 ≈ 2.2K, and the audio of main control chip is defeated
Go out the I/O interface impedance of signal for 1K Ω, R1//R2 will carry out partial pressure to the audio output signal of main control chip.It is logical according to earphone
The requirement of the 300~500mV of virtual value of road exports audio signal amplitude, here R1 be preferably 3.3K Ω, R2 is preferably 6.8K Ω.
2nd, filter circuit 212 is described in detail below：
Exemplary, as shown in figure 3, filter circuit 212 includes the 5th electric capacity C5 and the 6th electric capacity C6.Wherein, C5 and C6
Being electrically connected between the colelctor electrode of emitter follower circuit 211 and ground after parallel connection.C5 and C6 can be used as the decoupling of power supply electricity
Hold, for filtering the noise in exports audio signal.
2nd, control module 220 is specifically described：
Exemplary, Fig. 4 is a kind of control circuit diagram that the embodiment of the present invention two is provided.As shown in fig. 4 and fig. 2,
Control module includes：First power supply+12_NOR；Second source+3.3V_Standby；4th resistance R4；5th resistance R5；6th
Resistance R6, after the 6th resistance R6 connects with the 5th resistance R5, is connected between the first power supply+12_NOR and ground；7th electricity
Resistance R7；8th resistance R8；First diode D1, is connected in parallel on the two ends of the 8th resistance R8；Second diode D2；3rd diode
D3, the positive terminal of the 3rd diode D3 is connected by the 7th resistance R7 with second source+3.3V_Standby, the three or two pole
The negative pole end of pipe D3 states the negative pole end connection of the second diode D2；Second triode Q2, the base stage of second triode passes through
4th resistance R4 is connected with the positive pole of the first diode D1, and the colelctor electrode of the second triode Q2 passes through the second diode D2 and first
The base stage connection of triode Q1, the emitter stage of the second triode Q2 is connected by the 5th resistance R5 with the first power supply+12_NOR；The
Three electric capacity C3, are connected in parallel on the two ends of the 6th resistance R6；4th electric capacity C4, is connected to the positive terminal and ground of the first diode D1
Between.
Preferably, the second triode Q2 is PNP type triode.
Specifically, the first power supply+12_NOR is the direct current that AC-DC systems board is started shooting and/or is powered when standby
Source, when+3.3V_Standby is that board DC-DC starts shooting and/or be standby, the dc source being powered.+ 12_NOR can also be used
+ 5V_NOR substitute ,+5V_NOR be system board DC-DC start shooting dc source, it is standby after be changed into 0V.
In system exchange during electric (start) ,+12_NOR is charged by the 5th resistance R5 to the 3rd electric capacity C3, and the time is normal
Number τ1=RC=R5 × C3=0.940S, while+12_NOR charges also by the 8th resistance R8 to the 4th electric capacity C4.Similarly, when
Between constant, τ2=RC=R8 × C4=2.21S.By after 3~5 RC, charging process terminates substantially.Due to τ1<τ2, therefore,
In charging process, the voltage of the voltage higher than C4 of C3, the i.e. V of the voltage between the second triode Q2 base stages and emitter stageEB>0, because
It is τ1With τ2Differ larger (1.27S), therefore, with the increase of C3 and C4 pressure differences, Q2 conducting speed is accelerated so that enable MUTE_
EN networks are high level, and act on mute circuit.
During the system AC dump (shutdown) ,+12V_NOR can be from the point of view of simply equivalent G ND, and C3 is put by R5 with R6
Electricity.Now, τ1*=RC=(R6//R5) × C3=0.827S, after also passing through 3~5 time constants, electric capacity can discharge knot
Beam.The two ends of the 8th resistance R8 are connected in parallel on due to the first diode D1, therefore the discharge loop R8 of C4 can be by the first diode D1
Bypass, electric discharge terminates very fast.Such second triode Q2 meeting horses during powering off turn on immediately, and then cause to enable MUTE_EN
Network is high level, and acts on mute circuit.
Exemplary, as shown in figure 4, when system is in start or standby period, the I/O interface of main control chip can direct effect
In AMP_MUTE networks, MUTE_EN networks are made to produce high level, control mute circuit effect.
It should be noted that：The selection of R5 and R6 resistances, is in order that the upper electricity of exchange terminates why using two resistance
C3 voltages are less than 12V, the V of the voltage between the base stage and emitter stage of the second triode Q2 after circuit normal workEB<0, the 2nd 3
Pole pipe Q2 is completely in cut-off state.When so setting can prevent circuit normal work, made due to triode Q2 misoperations
Jing Yin enable.
3rd, Jing Yin module 230 is specifically described：
Exemplary, Fig. 5 is a kind of monophonic mute circuit schematic diagram that the embodiment of the present invention two is provided.As shown in figure 5,
Jing Yin module includes：3rd resistor R3, the first metal-oxide-semiconductor QM1, the second metal-oxide-semiconductor QM2 and the first triode Q1.
Wherein, 3rd resistor R3 is connected between the negative pole end of the second electric capacity C2 and ground, for being carried for second electric capacity
For charging and discharging circuit；First metal-oxide-semiconductor QM1 and the second metal-oxide-semiconductor QM2 differential concatenations, for eliminating system electrification and/or turnoff time
Between, the noise in the audio signal；The colelctor electrode of the first triode Q1 is connected with the grid of the first metal-oxide-semiconductor QM1, the one or three pole
The grounded emitter of pipe Q1, the base stage of the first triode Q1 is connected with the Enable Pin of the control module 220, for according to control
Level signal controls turning on and off for first and second metal-oxide-semiconductor.
Preferably, as shown in figure 5, the first metal-oxide-semiconductor QM1 and the second metal-oxide-semiconductor QM2 are the enhanced metal-oxide-semiconductor of N-channel, its base
This characteristic is metal-oxide-semiconductor conducting when grid is more than cut-in voltage with source voltage.Because QM1 and QM2 is in earphone peripheral circuit
In mainly play a part of switch, so preferably more common model 2N7002 in this programme.Specifically, univers parameter is full
Sufficient design specification is：VGS(th)Representative value is 2.5V, VGSLimiting value is ± 30V, VDSMaximum is 60V, IDMaximum is 300mA.
First triode Q1 is also to play simple on-off action, model preferably same with emitter follower circuit in this programme
(KMBT390).Electric power network is+5V_NOR, more than VGS(th)Representative value 2.5V, it can be ensured that the normally of metal-oxide-semiconductor.
Exemplary, Jing Yin module also includes：7th electric capacity C7, be connected in parallel on load RL two ends, for filter export to
Clutter in the audio signal of load.
Exemplary, load RL in circuit as shown in Figure 5, in figure and be equivalent to 32 ohm of earphone impedances.In system electrification
During, 5V power supplys can be changed into 5V from 0V, and Q3 emitting stages current potential also can be changed into corresponding DC level from 0V, this process equivalent to
Exchange, the second electric capacity (being herein electrochemical capacitor, preferably 220 μ F) C2 will not play isolation direct current during without full of electric charge
Effect, therefore, the direct impulse of one fixed width will be had when charge circuit is by earphone.It is right because earphone load is smaller
After direct impulse is more sensitive, therefore the direct impulse enters user's ear, the subjective feeling of user is exactly the noise of ' crack '.
And the discharge loop of the electric capacity of power down process second can again pass by earphone, earphone is set to be responsible for producing the reverse impulse of one fixed width,
Pleasant subjective feeling is equally the noise of ' crack '.Therefore, the second electric capacity be produce " crack " main source of noise.But
Due to sound frequency response requirement, (the second electric capacity C2 is the coupled capacitor of output signal, the direct current the purpose is to cut off the output of its front end
Voltage), so the electric capacity can not be removed.In sum, as long as electrochemical capacitor discharge and recharge is returned during ensureing system electrification and power-off
Road is without earphone load, then the positive pulse and negative pulse of one fixed width would not be produced on load RL, would not also be produced
Raw ' crack ' noise.
Exemplary, Fig. 6 is that the present invention implements a kind of two single channel earphone drive circuit figures with mute circuit for providing.
As shown in fig. 6, the high level for producing one fixed width by control module 220 during upper electricity enables MUTE_EN networks, make first
The grid level of metal-oxide-semiconductor QM1 and the second metal-oxide-semiconductor QM2 is dragged down, and QM1 and QM2 is turned off, and the second electric capacity is charged by resistance R9, treated
Electric process terminates C2 and is filled substantially with electric charge, and the enabling pulse of the MUTE_EN networks that control module 220 is produced terminates, the first three-level
Pipe Q1 is by QM1 and QM2 recovers normal work.Power down process is identical with the above principle, controls circuit to produce during power down
, in MUTE_EN, Q1 is by QM1 and QM2 is turned off, and the second electric capacity is returned by R3 and R9 for the positive signal function that enables of one fixed width
Discharge on road.
It should be noted that QM1 and QM2 palpus differential concatenations, and pin network is as shown in Figure 6.The enhanced metal-oxide-semiconductor of N-channel
As long as ensureing VGS>VGS(th), then drain D and will be formed with the conducting channel between simple S, QM1 and QM2 will be on shape
State, electric current can flow to source class by drain, also can source class flow to drain, determined with specific reference to two-stage voltage swing.Can from Fig. 6
Know, that QM1 is connected with the grid of QM2 is 5V, so two metal-oxide-semiconductors are all in fully on state under normal operating conditions.Cause
Be MOS inside with the presence of parasitic diode itself, direction be by source class to drain, will when metal-oxide-semiconductor is operated in pinch off region
Metal-oxide-semiconductor is set thoroughly to turn off, parasitic diode itself provides charge or discharge loop for the second electric capacity C2, equally has
Charging and discharging currents flow through earphone load, and ' crack ' noise is still present.If only retaining QM1, its parasitic diode D4 during power-off
Will act on, load RL occurs negative pulse；If only retaining QM2, its parasitic diode D5 will be acted on when upper electric, load RL
Positive pulse occurs.But, no matter when positive pulse or negative pulse, human ear subjectivity goes to listen all is ' crack ' noise.Such as Fig. 5 institutes
Show, if two metal-oxide-semiconductor differential concatenations, then when metal-oxide-semiconductor is turned off, parasitic diode can mutually block its path makes metal-oxide-semiconductor
Thoroughly shut-off effect is reached, earphone load is flowed through there will be no charging and discharging currents.Therefore, by by the first metal-oxide-semiconductor QM1 and
Two metal-oxide-semiconductor QM2 differential concatenations, can eliminate system it is upper electricity, power-off, it is standby and start during, in audio signal " crack "
Noise.
The present embodiment is on the basis of above-described embodiment, there is provided a kind of earphone peripheral circuit for eliminating noise.By profit
With the charge-discharge characteristic of the RC circuits in control module, MUTE_EN networks are made to produce the high level of a period of time Jing Yin to control
Circuit, acts on it.By way of by the double metal-oxide-semiconductors in mute circuit using differential concatenation, system can be eliminated upper electric, disconnected
Electricity, start and/or it is standby when noise.Treat that ear puts the earphone output circuit of IC, the technical scheme of the present embodiment relative to tradition
In the case where headset output interface standard is met, cost is relatively low, output is stable and highly versatile, can bring user good receipts
Listen experience.
Note, above are only presently preferred embodiments of the present invention and institute's application technology principle.It will be appreciated by those skilled in the art that
The invention is not restricted to specific embodiment described here, can carry out for a person skilled in the art various obvious changes,
Readjust and substitute without departing from protection scope of the present invention.Therefore, although the present invention is carried out by above example
It is described in further detail, but the present invention is not limited only to above example, without departing from the inventive concept, also
More other Equivalent embodiments can be included, and the scope of the present invention is determined by scope of the appended claims.
Claims (10)
1. a kind of peripheral circuit for eliminating noise signal, for eliminating the circuit system that is connected with audio-frequency load upper electric or power off
Period, the noise signal in the audio signal of output, the peripheral circuit includes main control chip, it is characterised in that the periphery
Circuit also includes：
Drive module, is connected between the main control chip and the audio-frequency load, for being converted by impedance, strengthens the sound
The carrying load ability of frequency signal；
Jing Yin module, the output end of the Jing Yin module is connected with the drive module；
Control module, is connected between the main control chip and Jing Yin module, for electricity or turnoff time in the circuit system
Between produce control level signal；
The Jing Yin module is used for, and according to the control level signal, eliminates the noise signal in the audio signal.
2. circuit according to claim 1, it is characterised in that the drive module includes：
Emitter follower circuit, is connected between the main control chip and the audio-frequency load, for reducing the defeated of main control chip
Go out impedance, strengthen the carrying load ability of audio signal；
Filter circuit, is connected between the colelctor electrode of the emitter follower and ground, and the noise of power end is coupled to for reducing.
3. circuit according to claim 2, it is characterised in that the emitter follower circuit includes：
First electric capacity, is connected between the base stage of the main control chip and the emitter follower circuit, for cutting off input
DC voltage in audio signal；
Second electric capacity, is connected between the emitter stage of the emitter follower circuit and the audio-frequency load, for completely cutting off direct current,
The audio signal is exported to the audio-frequency load；
First resistor；With
Circuit after second resistance, the second resistance and first resistor series connection, is connected to first power supply with ground
Between, for carrying out partial pressure to the audio signal that the main control chip is exported.
4. circuit according to claim 3, it is characterised in that the Jing Yin module includes：
3rd resistor, is connected between the negative pole end of second electric capacity and ground, for providing discharge and recharge for second electric capacity
Loop；
First and second metal-oxide-semiconductors, the first and second metal-oxide-semiconductors differential concatenation, for eliminate the circuit system it is upper electricity or
During power-off, the noise in the audio signal；
First triode, the colelctor electrode of first triode is connected with the grid of first metal-oxide-semiconductor, first triode
Grounded emitter, the base stage of first triode is connected with the Enable Pin of the control module, for according to the control
Level signal controls turning on and off for first and second metal-oxide-semiconductor.
5. circuit according to claim 4, it is characterised in that the control module includes：
First power supply；
Second source；
4th resistance；
5th resistance；
After 6th resistance, the 6th resistance and the 5th resistant series, it is connected between first power supply and ground；
7th resistance；
8th resistance；
First diode, is connected in parallel on the two ends of the 8th resistance；
Second diode；
3rd diode, the positive terminal of the 3rd diode is connected by the 7th resistance with second source, and the described 3rd
The negative pole end of diode is connected with the negative pole end of second diode；
Second triode, the base stage of second triode is connected by the 4th resistance with the positive pole of first diode
Connect, the colelctor electrode of second triode is connected by second diode with the base stage of first triode, described
The emitter stage of two triodes is connected by the 5th resistance with first power supply；
3rd electric capacity, is connected in parallel on the two ends of the 6th resistance；With
4th electric capacity, is connected between the positive terminal of first diode and ground.
6. circuit according to claim 2, it is characterised in that the filter circuit includes：
5th electric capacity；
6th electric capacity, it is in parallel with the 5th electric capacity after circuit, be connected to the colelctor electrode of the emitter follower circuit with ground
Between.
7. circuit according to claim 4, it is characterised in that the Jing Yin module also includes：7th electric capacity, is connected in parallel on institute
State the two ends of audio-frequency load.
8. circuit according to claim 4, it is characterised in that：First triode is NPN type triode.
9. circuit according to claim 4, it is characterised in that：First and second metal-oxide-semiconductor is the enhanced MOS of N-channel
Pipe.
10. circuit according to claim 5, it is characterised in that：Second triode is PNP type triode.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710244157.2A CN106878872B (en) | 2017-04-14 | 2017-04-14 | Peripheral circuit for eliminating noise signal |
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| CN201710244157.2A CN106878872B (en) | 2017-04-14 | 2017-04-14 | Peripheral circuit for eliminating noise signal |
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| CN106878872B CN106878872B (en) | 2019-12-27 |
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| CN107371093A (en) * | 2017-07-27 | 2017-11-21 | 广东长虹电子有限公司 | A kind of audio amplifier circuit |
| CN108200518A (en) * | 2018-03-07 | 2018-06-22 | 合肥惠科金扬科技有限公司 | A kind of voicefrequency circuit and audio frequency apparatus for eliminating powered on moment noise |
| CN110430497A (en) * | 2019-07-31 | 2019-11-08 | 深圳市睿耳电子有限公司 | A kind of circuit, Radiationproof screening apparatus for back-located antenna mobile telephone and earphone that control microphone is mute |
| CN111263268A (en) * | 2020-01-15 | 2020-06-09 | 深圳市创维群欣安防科技股份有限公司 | Loudspeaker POP sound cancelling circuit and electronic product during outage |
| CN113110241A (en) * | 2021-05-13 | 2021-07-13 | 中科可控信息产业有限公司 | Electronic equipment and audio control method thereof |
| CN116112846A (en) * | 2022-10-08 | 2023-05-12 | 广州市保伦电子有限公司 | Restarting impact sound eliminating circuit and audio circuit |
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| CN113110241A (en) * | 2021-05-13 | 2021-07-13 | 中科可控信息产业有限公司 | Electronic equipment and audio control method thereof |
| CN116112846A (en) * | 2022-10-08 | 2023-05-12 | 广州市保伦电子有限公司 | Restarting impact sound eliminating circuit and audio circuit |
| CN116112846B (en) * | 2022-10-08 | 2024-01-30 | 广东保伦电子股份有限公司 | Restarting impact sound eliminating circuit and audio circuit |
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