CN203851278U - Audio input/output device - Google Patents
Audio input/output device Download PDFInfo
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- CN203851278U CN203851278U CN201420138070.9U CN201420138070U CN203851278U CN 203851278 U CN203851278 U CN 203851278U CN 201420138070 U CN201420138070 U CN 201420138070U CN 203851278 U CN203851278 U CN 203851278U
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Abstract
The utility model provides an audio input/output device which comprises a microcontroller, an audio input port and an audio output port. The output port of the microcontroller is connected with the input port of a digital-to-analog converter. The output port of the digital-to-analog converter is connected with a first input port of a first operational amplifier. The audio input port is connected with the first input port of the first operational amplifier. An output port of the first operational amplifier is connected with a first input port of a voltage comparator. An output port of the voltage comparator outputs a comparing level to the microcontroller. The output port of the first operation amplifier outputs a signal to the first input port of a second operation amplifier. A third switch and a rheostat which are connected in parallel are connected between the first input port of the second operational amplifier and the output port of the second operational amplifier. The audio input/output device provided by the utility model realizes no noise in switching between an inner sound source and outer audio and has low production cost.
Description
Technical field
The utility model relates to integrated circuit fields, particularly, is a kind of audio frequency input/output unit.
Background technology
Present audio-frequence player device, audio frequency such as the different audio-source of the common energy such as MP3 music player, mobile phone output multi-channel, for example, in audio-frequence player device, be integrated with Bluetooth chip and FM radio reception chip, Bluetooth chip audio reception data, FM radio reception chip is by radio wave reception FM audio signal, and the audio signal that Bluetooth chip and FM radio reception chip are exported all can be play by audio-frequence player device.
Existing audio-frequence player device arranges an audio frequency main control chip conventionally, and receives respectively the audio signal of the outputs of external sound source chip such as Bluetooth chip and FM radio reception chip, and the signal of reception is processed to rear drive loudspeaker or earphone work.Because the external sound source chips such as audio frequency main control chip and FM radio reception chip are independent design and manufacture respectively normally, audio frequency DC level is separately variant unavoidably.In the situation that DC level there are differences, if the analogue audio frequency output signal of FM radio reception chip directly connects with audio frequency main control chip analogue audio frequency input, when selecting so to switch between inner source of sound and external sound source, the audio frequency output DC level of audio frequency main control chip just has unexpected variation, and loudspeaker or earphone send ear-piercing explosion sound thereupon.In addition, if the analogue audio frequency AC signal amplitude of external sound source very greatly even approaches full width, the skew of DC level can cause the audio output signal slicing of audio frequency main control chip so, and loudspeaker or earphone send the clipped noise that makes us irritated thereupon.In addition,, if the audio frequency of the audio frequency DC level of external sound source and main control chip output DC level is variant, when adjustment audio frequency output AC signal amplitude is adjusted volume, the difference of DC level can be added in volume adjusting range.Conventionally, the difference of DC level is much larger with respect to volume adjustment step pitch.In this case, while adjusting volume, loudspeaker or earphone will send obvious volume and adjust noise.Three kinds of above-mentioned situations all produce larger noise, therefore greatly affect the sense of hearing.
Therefore, the analogue audio frequency input of the audio frequency main control chip of more existing audio-frequence player devices is provided with the level biasing circuit mating with the analogue audio frequency output DC level of audio frequency main control chip.And the left and right acoustic channels of FM radio reception chip is all connected with the analogue audio frequency input of audio frequency main control chip by capacitance, as shown in Figure 1.The L channel of FM radio reception chip 11 is connected to the input port of audio frequency main control chip 10 by capacitance C1, R channel is connected to the input port of audio frequency main control chip 10 by capacitance C2.In the same manner, the L channel of Bluetooth chip 12 is connected to the input port of audio frequency main control chip 10 by capacitance C3, and R channel is connected to the input port of audio frequency main control chip 10 by capacitance C4.
Yet, development along with electronic technology, the level of integrated system of audio-frequence player device is more and more higher, in the more and more advanced situation of the encapsulation technology of audio frequency main control chip and external sound source chip, start to utilize multi-chip package (MCP) technology that audio frequency main control chip is become to a case chip with FM radio reception Chip Vertical stacked package, further save encapsulating material cost and Product jointing process cost.But MCP technology is still subject to the restriction of audio frequency input and output DC level mismatch problem.Therefore, adopt after MCP technology, still need the left and right output channels pin of FM radio reception chip to be drawn out to the outside of MCP packaged chip, be connected to again capacitance, then be connected in MCP packaged chip, audio frequency input pin with audio frequency main control chip connects, and this way has increased packaging cost and the difficulty of chip greatly.
Utility model content
Main purpose of the present utility model can not produce the audio frequency input/output unit that noise and packaging cost are low while being to provide a kind of inner source of sound and external sound source switching.
In order to realize above-mentioned main purpose, the audio frequency input/output unit that the utility model provides has microcontroller and audio input port, audio output port, wherein, the output port of microcontroller is connected to the input port of digital to analog converter, the output port of digital to analog converter is connected to the first input end mouth of the first operational amplifier by the first switch, audio input port is connected to the first input end mouth of the first operational amplifier by second switch, the second input port of the first operational amplifier receives the reference level of reference level generator output, the output port of the first operational amplifier is connected to the first input end mouth of voltage comparator, the second input port of voltage comparator receives the reference level of reference level generator output, the output port of voltage comparator is exported comparative level to microcontroller, the output port of the first operational amplifier is to the first input end mouth output signal of the second operational amplifier, the second input port of the second operational amplifier receives the reference level of reference level generator output, the second operational amplifier is connected to audio output port, between the first input end mouth of the second operational amplifier and the output port of the second operational amplifier, be connected with the 3rd switch and the adjustable resistance being connected in parallel.
From such scheme, the inside source of sound of audio-frequence player device is by microcontroller output audio signal and convert analog signal output to by digital to analog converter, and external sound source chip exports audio signal to audio input port.By closure and the opening operation of three switches, and by regulating the resistance of adjustable resistance, can make the output level of the second operational amplifier be subject to hardly the impact of the output level of the first operational amplifier, while switching, can not produce noise between inner source of sound and external sound source.
And, owing to not needing to arrange capacitance between external sound source chip and audio frequency input/output unit, greatly reduce encapsulation difficulty and the packaging cost of chip.
Preferably, between the output port of digital to analog converter and the first switch, be connected with the first resistance, between audio input port and second switch, be connected with the second resistance, between the first input end mouth of the first operational amplifier and the described output port of the first operational amplifier, be connected with the 3rd resistance, and the first resistance, the second resistance equate with the resistance of the 3rd resistance, between the output port of the first operational amplifier and the first input end mouth of the second operational amplifier, are connected with the 4th resistance.
Accompanying drawing explanation
Fig. 1 is the structure chart of existing audio frequency input/output unit.
Fig. 2 is the circuit diagram that the utility model audio frequency input/output unit embodiment is connected with Bluetooth chip, FM radio reception chip.
Fig. 3 is the circuit diagram of the utility model audio frequency input/output unit embodiment.
Below in conjunction with drawings and Examples, the utility model is described in further detail.
Embodiment
Audio frequency imput output circuit of the present utility model is the audio frequency main control chip such as MP3 music player, mobile phone etc., it can play inner audio signal, and can receive the external sound source signal such as Bluetooth chip, FM radio reception chip, and export inner sound source signal or external sound source signal to loudspeaker or earphone etc.
Referring to Fig. 2, audio frequency main control chip 20 of the present utility model is electrically connected to FM radio reception chip 21, Bluetooth chip 22, audio frequency main control chip 20 is provided with microcontroller, digital to analog converter DAC, reference level generator VCMG, voltage comparator CMP, the first operational amplifier A MP1, the second operational amplifier A MP2, audio input port AIN receives the audio level signal after the external sound source chip outputs such as FM radio reception chip, and audio output port AOUT is to output audio signals such as loudspeaker, earphones.In addition, audio frequency main control chip 20 is provided with four resistance R 1, R2, R3, R4 and adjustable resistance R5 that resistance value is fixing, is also provided with three switch s1, switch s2, switch S 3.
Referring to Fig. 3, the output port of microcontroller is electrically connected to the input port of digital to analog converter DAC, to digital to analog converter DAC output signal.When audio frequency main control chip 20 is play inner source of sound, the signal after microcontroller is exported to digital to analog converter DAC is inner sound source signal, and digital to analog converter DAC converts digital signal to analog level signal output.
Digital to analog converter DAC is connected to the negative input port of the first operational amplifier A MP1 by switch s1, and, between digital to analog converter DAC and switch S 1, be connected with resistance R 1.Audio input port AI N is connected to the negative input port of the first operational amplifier A MP1 by switch s2, and is connected with resistance R 2 between audio input port AI N and switch S 2.
The positive input port of the first operational amplifier A MP1 is connected to reference level generator VCMG, by reference level generator VCMG output reference level V
cM.Between the negative input port of the first operational amplifier A MP1 and output port, be connected with resistance R 3, preferably, the resistance value of resistance R 1, R2, R3 all equates.
The output port of the first operational amplifier A MP1 is connected to the positive input port of voltage comparator CMP, and the negative input port of voltage comparator CMP is connected to reference level generator VCMG, receives reference level generator VCMG output reference level V
cM.The output port of voltage comparator CMP is connected with microcontroller, to microcontroller output comparative level.According to the characteristic of voltage comparator CMP, when the level of its positive input port is during higher than the level of negative input port, it exports high level signal, when the level of positive input port is during lower than the level of negative input port, and its output low level signal.
The output port of the first operational amplifier A MP1 is connected to the negative input port of the second operational amplifier A MP2 by resistance R 4, the positive input port of the second operational amplifier A MP2 is connected to reference level generator VCMG, receives reference level generator VCMG output reference level V
cM.The output port of the second operational amplifier A MP2 is connected with audio output port AOUT.And, between the negative input port of the second operational amplifier A MP2 and output port, be connected with the switch S 3 and the adjustable resistance R5 that are connected in parallel.
When audio-frequence player device is play inner source of sound, by microcontroller to digital to analog converter DAC outputting audio data, digital to analog converter DAC converts digital signal to the level signal of simulation, output after the first operational amplifier A MP1 of audio frequency main control chip 20 and the second operational amplifier A MP2 amplify level signal, the utility model definition audio frequency output state is now DAC broadcast state.In order to ensure audio frequency play quality, the triggering level of digital to analog converter DAC need to be set, concrete steps are as follows:
Under initial condition, switch S 1, S2 disconnect, under the state of switch S 3 closures, and the output reference level V of reference level generator VCMG
cM.Because switch s1, s2 all disconnect, the negative input port of the first operational amplifier A MP1 is unsettled, and according to the characteristic of the first operational amplifier A MP1, resistance R 3 no currents pass through, so node 1, i.e. the magnitude of voltage V at the output port place of the first operational amplifier A MP1
1with reference level V
cMequate.Now, because switch s3 is closed, the negative input port of the second operational amplifier A MP2 and its output port short circuit, so node 2, i.e. the magnitude of voltage V at the output port place of the second operational amplifier A MP2
2also with reference level V
cMequate, so there is V
2=V
1=V
cM.
Then, Closing Switch S1, switch S 1, S3 are closed, and switch S 2 disconnects.Microcontroller, to the input port supplied with digital signal of analog to digital converter DAC, is controlled the output port output DC level V of digital to analog converter DAC
cMD, while enable voltage comparator C MP.According to the first operational amplifier A MP1 characteristic, can calculate the magnitude of voltage V of the first operational amplifier A MP1 output port
1be:
Known according to the feature of voltage comparator CMP: if V
cMD<V
cM, V so
1>V
cM, voltage comparator CMP exports high level signal.If V
cMD>V
cM, V so
1<V
cM, voltage comparator CMP output low level signal.According to the signal of voltage comparator CMP output comparative level, regulate the DC voltage value V of digital to analog converter DAC
cMD, in conjunction with the feature of the first operational amplifier A MP1, can change the input voltage V of the positive input port of voltage comparator CMP
1.
If current voltage comparator C MP exports high level signal, can increase the output level V of digital to analog converter DAC
cMD, V
1magnitude of voltage diminishes, until V
1<V
cM, voltage comparator CMP output voltage values becomes low level from high level, realizes the upset of signal.
If current voltage comparator C MP output low level signal, can reduce the level V that digital to analog converter DAC exports
cMD, V
1it is large that magnitude of voltage becomes, until V
1>V
cM, voltage comparator CMP output voltage values becomes high level from low level, also realizes the upset of signal.
When the state turnover of voltage comparator CMP output signal, the output voltage of the first operational amplifier A MP1 is to V
1approach very much reference level V
cM, can think now V
1=V
cM.Now, microcontroller is to an original levels signal of input port input of digital to analog converter DAC, and digital to analog converter DAC exports DC level signal V
cMD0, and VC
mD0=V
1=V
2=V
cM.
Then, Closing Switch s2, switch s1, s2, s3 are in closure state, and FM radio reception chip 21 is exported its audio level signal V to the audio input port AI N of audio frequency main control chip 20
cMF, according to the first operational amplifier A MP1 characteristic, can calculate:
Due to current V
cMD=V
cMD0=V
cM, can draw
Known according to the feature of voltage comparator CMP, if V
cMF<V
cM, V so
1>V
cM, voltage comparator CMP exports high level signal.If V
cMF>V
cM, V so
1<V
cM, voltage comparator CMP output low level signal.
According to the signal of voltage comparator CMP output, can regulate the magnitude of voltage V of digital to analog converter DAC output
cMD, in conjunction with the feature of the first operational amplifier A MP1, can change the magnitude of voltage V of the positive input port of voltage comparator CMP
1.
If current voltage comparator C MP exports high level signal, can increase digital to analog converter DAC output voltage values V
cMD, V
1magnitude of voltage diminishes, until V
1<V
cM, the magnitude of voltage of the defeated CMP output of voltage comparator becomes low level from high level.If current voltage comparator C MP output low level signal, reduces the magnitude of voltage V that digital to analog converter DAC exports
cMD, V
1it is large that magnitude of voltage becomes, until V
1>V
cM, the magnitude of voltage of voltage comparator CMP output becomes high electric hand from low level.
When the state turnover of voltage comparator CMP output level, V
1magnitude of voltage approaches reference level V very much
cM, can think now V
1=V
cM.Now, microcontroller is to the input port input triggering level of digital to analog converter DAC, and digital to analog converter DAC exports triggering level signal V
cMD1, V now
1=V
2=V
cM, the output level of the output level of the first operational amplifier A MP1, the second operational amplifier A MP1 is equal to reference level.
Arrange after triggering level, introduce the step of switching from initial condition to DAC broadcast state below.Under initial condition, switch S 1 disconnects, S2 disconnects, switch S 3 closures.During switching, Closing Switch S1 first, switch S 1, S3 are closed, and switch S 2 disconnects.Then, microcontroller is inputted initial level signal to the input port of digital to analog converter DAC, controls the output port output DC level signal V of digital to analog converter DAC
cMD0.Now, V
1=V
2=V
cM, the output level of the output level of the first operational amplifier A MP1, the second operational amplifier A MP1 is equal to reference level.
Then, cut-off switch S3, switch S 1 closure now, switch S 2, S3 disconnect, and adjustable resistance R5 both end voltage equates, does not have electric current to pass through.Then, regulate the resistance of adjustable resistance R5 to minimum value.Now have:
Then, microcontroller is exported continuous voice data to the input port of digital to analog converter DAC, controls the output port output audio level signal V of digital to analog converter DAC
aUDIO.Now have
Because the resistance of resistance R 5 is very little, the magnitude of voltage V of the first operational amplifier A MP1 output
1variation can affect hardly the magnitude of voltage V of the second operational amplifier A MP2 output
2.So digital to analog converter DAC output audio level signal is by initial level signal V
cMD0v while becoming audio frequency output
aUDIOprocess, can not produce any noise.
Finally, regulate adjustable resistance R5 to being applicable to resistance, the magnitude of voltage V that allows the second operational amplifier A MP2 export
2follow the magnitude of voltage V of the first operational amplifier A MP1 output
1change, thereby follow V
aUDIOvariation.Now, audio output port AOUT plays out audio signal, completes initial condition to the handoff procedure of DAC broadcast state.
During switching from DAC broadcast state to initial condition, carry out contrary operation, regulate adjustable resistance R5 to minimum value, allow V
2=V
cM, audio output port AOUT stops playing out audio signal, then, Closing Switch S3, switch S 1, S3 are closed, and switch S 2 disconnects, last, cut-off switch S1, switch S 1, S2 disconnect, and switch S 3 is closed.
While receiving the audio signal of outside FM radio reception chip 21 or Bluetooth chip 22 outputs as audio frequency main control chip 20, by audio input port AI N audio reception level signal, the utility model claims that broadcast state is now AIN broadcast state.
Introduce the switching from initial condition to AIN broadcast state below.Under initial condition, switch S 1 disconnects, S2 disconnects, switch S 3 closures.During switching, first Closing Switch S1 and switch S 2, three switch S 1, S2, S3 are all closed.Then, microcontroller, to the input port input triggering level signal of digital to analog converter DAC, is controlled the output port output triggering level signal V of digital to analog converter DAC
cMD1.FM radio reception chip 21 is exported its audio frequency DC level V to the audio input port AIN of audio frequency main control chip 20
cMF, V now
2=V
1=V
cM.
Then, cut-off switch S1, S3, switch S 1, S3 disconnect, and the closed variable resistor R5 of switch S 2 both end voltage is equal, and no current passes through.Regulate variable resistor R5 to minimum value, now have
FM radio reception chip 21 is to the audio input port AIN output audio level signal V of audio frequency main control chip 20
aUDIOFM.Now have
Because the resistance of adjustable resistance R5 is very little, the magnitude of voltage V of the first operational amplifier A MP1 output
1magnitude of voltage change the magnitude of voltage V can affect hardly the second operational amplifier A MP2 output
2voltage.So FM radio reception chip 21 output audio level signals are by V
cMFbecome V
aUDIOFMprocess, the magnitude of voltage V of the second operational amplifier A MP2 output
2voltage can not fluctuate, just can not produce any noise yet.
Finally, regulate variable resistor R5 to being applicable to resistance, increase the resistance of adjustable resistance R5, the magnitude of voltage V that allows the second operational amplifier A MP2 export
2follow the magnitude of voltage V of the first operational amplifier A MP1 output
1magnitude of voltage change, thereby follow V
aUDIOFMchange.Like this, audio output port AOUT plays out audio signal, completes initial condition to the handoff procedure of AIN broadcast state.
During switching from AIN broadcast state to initial condition, carry out inverse operation, regulate variable resistor R5 to minimum value, audio output port AOUT stops playing out audio signal.Then, Closing Switch S3, switch S 1, S3 are closed, and switch S 2 disconnects, last cut-off switch S1 and switch S 2, switch S 1, S2 disconnect, and switch S 3 closures, are accomplished to the switching of initial condition.
From such scheme, audio frequency imput output circuit of the present utility model can be realized switching and the switching from initial condition to external sound source broadcast state from initial condition to inner source of sound broadcast state reposefully, can not produce noise like this when inner source of sound broadcast state is switched to outside.And, during due to chip package, not needing to arrange capacitance, the encapsulation of chip is simple, and production cost is low.
Finally it is emphasized that; the utility model is not limited to above-mentioned execution mode, as operational amplifier, the change of voltage comparator particular circuit configurations, the variations such as change of the resistance value of each resistance also should be included in the protection range of the utility model claim.
Claims (6)
1. audio frequency input/output unit, comprising:
Microcontroller and audio input port, audio output port;
It is characterized in that:
The output port of described microcontroller is connected to the input port of digital to analog converter, the output port of described digital to analog converter is connected to the first input end mouth of the first operational amplifier by the first switch, described audio input port is connected to the described first input end mouth of described the first operational amplifier by second switch, the second input port of described the first operational amplifier receives the reference level of reference level generator output;
The output port of described the first operational amplifier is connected to the first input end mouth of voltage comparator, the second input port of described voltage comparator receives the reference level of described reference level generator output, and the output port of described voltage comparator is to described microcontroller output comparative level;
The output port of described the first operational amplifier is to the first input end mouth output signal of the second operational amplifier, the second input port of described the second operational amplifier receives the reference level of described reference level generator output, and described the second operational amplifier is connected to described audio output port;
Between the described first input end mouth of described the second operational amplifier and the described output port of described the second operational amplifier, be connected with the 3rd switch and the adjustable resistance being connected in parallel.
2. audio frequency input/output unit according to claim 1, is characterized in that:
Between the described output port of described digital to analog converter and described the first switch, be connected with the first resistance.
3. audio frequency input/output unit according to claim 2, is characterized in that:
Between described audio input port and described second switch, be connected with the second resistance.
4. audio frequency input/output unit according to claim 3, is characterized in that:
Between the described first input end mouth of described the first operational amplifier and the described output port of described the first operational amplifier, be connected with the 3rd resistance.
5. audio frequency input/output unit according to claim 4, is characterized in that:
Described the first resistance, described the second resistance equate with the resistance of described the 3rd resistance.
6. according to the audio frequency input/output unit described in claim 1 to 5 any one, it is characterized in that:
Between the described first input end mouth of the described output port of described the first operational amplifier and described the second operational amplifier, be connected with the 4th resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420138070.9U CN203851278U (en) | 2014-03-25 | 2014-03-25 | Audio input/output device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420138070.9U CN203851278U (en) | 2014-03-25 | 2014-03-25 | Audio input/output device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203851278U true CN203851278U (en) | 2014-09-24 |
Family
ID=51564243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420138070.9U Withdrawn - After Issue CN203851278U (en) | 2014-03-25 | 2014-03-25 | Audio input/output device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203851278U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103888874A (en) * | 2014-03-25 | 2014-06-25 | 建荣集成电路科技(珠海)有限公司 | Audio input and output device and audio input and output method |
| CN107682588A (en) * | 2017-09-26 | 2018-02-09 | 珠海迈科智能科技股份有限公司 | Switching system, method and the signal measurement instrument of analog audio-video signal input and output |
| CN109587602A (en) * | 2017-09-29 | 2019-04-05 | 深圳市三诺数字科技有限公司 | A kind of audio signal boost control circuit |
-
2014
- 2014-03-25 CN CN201420138070.9U patent/CN203851278U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103888874A (en) * | 2014-03-25 | 2014-06-25 | 建荣集成电路科技(珠海)有限公司 | Audio input and output device and audio input and output method |
| CN107682588A (en) * | 2017-09-26 | 2018-02-09 | 珠海迈科智能科技股份有限公司 | Switching system, method and the signal measurement instrument of analog audio-video signal input and output |
| CN107682588B (en) * | 2017-09-26 | 2023-11-17 | 珠海迈科智能科技股份有限公司 | Analog audio/video signal input/output switching system, method and signal measuring instrument |
| CN109587602A (en) * | 2017-09-29 | 2019-04-05 | 深圳市三诺数字科技有限公司 | A kind of audio signal boost control circuit |
| CN109587602B (en) * | 2017-09-29 | 2024-05-17 | 深圳市三诺数字科技有限公司 | Audio signal boost control circuit |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
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| AV01 | Patent right actively abandoned |
Granted publication date: 20140924 Effective date of abandoning: 20170405 |