CN102026063A - Pseudo differential audio input circuit and installation method thereof - Google Patents
Pseudo differential audio input circuit and installation method thereof Download PDFInfo
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- CN102026063A CN102026063A CN2010105616859A CN201010561685A CN102026063A CN 102026063 A CN102026063 A CN 102026063A CN 2010105616859 A CN2010105616859 A CN 2010105616859A CN 201010561685 A CN201010561685 A CN 201010561685A CN 102026063 A CN102026063 A CN 102026063A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04R5/00—Stereophonic arrangements
- H04R5/04—Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments
Abstract
The invention discloses a pseudo differential audio input circuit and an installation method thereof, wherein the circuit comprises a first passage, a second passage, a high frequency interference filtering component, a voltage regulation component and an audio output port, wherein the first passage and the second passage are connected with an audio input port; the high frequency interference filtering component is arranged on the first passage and the second passage and used for filtering high frequency differential mode interference and high frequency common mode interference; the voltage regulation component is connected to the first passage and the second passage and used for leading the bias voltage on the first passage to be equal to the bias voltage on the second passage; and the first passage is connected to the audio output port. By the invention, the problem of common mode interference in the prior art can be solved, thus achieving the aims of improving audio transmission and storage quality.
Description
Technical field
The present invention relates to the communications field, in particular to a kind of pseudo-differential audio frequency input circuit and method to set up thereof.
Background technology
Existing mobile communication terminal the inside, audio interface has two kinds, a kind of is the monomer microphone interface, and a kind of is the ear microphone interface, aspect processing of circuit, it can be single-ended audio signal input, wherein one terminate to ground, single-ended audio signal is difficult to avoid being interfered sort circuit in signals transmission, can't remove the common mode disturbances in the analog channel, noise ratio is bigger; Another kind is the pseudo-differential input, in existing design, as shown in Figure 1, circuit comprises earphone interface, two biasing resistor R1, R2, filter capacitor C3, C4, C5, capacitance C1, C2, and audio input port, wherein by R1, R2 will move bias voltage on audio frequency two paths, it is the basis of realizing the pseudo-differential circuit, C3, C4 are connected respectively to ground, are used for the filtering high frequency differential mode to disturb, C3 cross-over connection two-way audio path filtering high frequency common mode is disturbed, 3 electric capacity is the filtering design to a certain characteristic frequency, and C 1, and C2 rises every the constant current purpose at audio input port.Biasing resistor R1 as seen from the figure, R2 makes biasing on the voice-frequency channel not on same level, be assumed to be v1 and v2 respectively, after the two-way audio input signal is subjected to common mode noise signal s interference, interference signals on the two-way audio signal path becomes v1*s and v2*s, when audio input port subtracts each other as difference, v1*s-v2*s=(v1-v2) s, because v1 is not equal to v2, so can't reach the effect that difference channel is eliminated common mode disturbances, still there are a large amount of noises to exist in the audio signal, influence the transmission of audio frequency to a certain extent and store quality.
Summary of the invention
Main purpose of the present invention is to provide a kind of pseudo-differential audio frequency input circuit and method to set up thereof, to address the above problem at least.
According to an aspect of the present invention, provide a kind of pseudo-differential audio frequency input circuit, it comprises: first path and the alternate path that link to each other with audio input port; Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb; Be connected to the voltage regulator components of described first path and described alternate path, be used to make bias voltage on described first path to equal bias voltage on the described alternate path; The audio output port that links to each other with described first path.
Further, described voltage regulator components comprises: the first biasing resistor R1, be connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node; The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node; Adjust resistance R 3, be connected between described alternate path and the ground, wherein, the tie point of described R3 and described alternate path is described second connected node; Wherein, the resistance between described R1, R2 and the R3 is closed and is: the resistance relation by described R1, R2 and R3 makes the voltage at the described first connected node place equate with the voltage at the described second connected node place.
Further, described R3 is an adjustable resistance.
Further, above-mentioned pseudo-differential audio frequency input circuit also comprises: isolated part, be connected between described first path and the described audio output port, and be used to isolate extraneous direct current and disturb and noise.
Further, described isolated part is an inductance L 1, is connected between described first connected node and the described audio output port.
Further, described High-frequency Interference filtering parts comprise: first capacitor C 1, be connected on described first path, and be used for isolated DC; Second capacitor C 2 is connected on the described alternate path, is used for isolated DC; The 3rd capacitor C 3, one ends link to each other with described C1, the other end with link to each other describedly, be used for the filtering high frequency differential mode and disturb; The 4th capacitor C 4 is connected across between described first path and the described alternate path, and an end is connected to described C1 and C3, and the other end is connected to described C2, is used for the filtering high frequency common mode and disturbs; The 5th capacitor C 5, one ends are connected to described C2 and described C4, and the other end links to each other with ground, are used for the filtering high frequency differential mode and disturb.
According to a further aspect in the invention, provide a kind of method to set up of pseudo-differential audio frequency input circuit, wherein, described circuit comprises: first path and the alternate path that link to each other with audio input port; Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb; Be connected to the voltage regulator components of described first path and described alternate path; The audio output port that links to each other with described first path; Described method comprises: regulate described voltage regulator components so that the bias voltage on described first path equals the bias voltage on the described alternate path.
Further, described voltage regulator components comprises: the first biasing resistor R1, be connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node; The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node; Adjust resistance R 3, be connected between described alternate path and the ground; Wherein, regulate described voltage regulator components so that the bias voltage on described first path equals the step of the bias voltage on the described alternate path comprises: the voltage of value up to the described first connected node place of regulating described R3 equates with the voltage at the described second connected node place.
Further, said method also comprises: between described first path and described audio output port isolated part is set, is used to isolate extraneous direct current and disturbs and noise.
Further, comprise in the step that isolated part is set between described first path and the described audio output port: between described first connected node and described audio output port, inductance L 1 is set.
In the present invention,, be used to make two bias voltages on the path to equate, solved and to have eliminated the problem of common mode disturbances in the prior art, and then reached the effect that improves audio transmission and store quality by the voltage regulator components that in difference channel, is provided with.
Description of drawings
Accompanying drawing described herein is used to provide further understanding of the present invention, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute improper qualification of the present invention.In the accompanying drawings:
Fig. 1 is the connection diagram according to the audio interface circuit of correlation technique;
Fig. 2 is a kind of preferred connection diagram according to the pseudo-differential audio frequency input circuit of the embodiment of the invention;
Fig. 3 is the another kind of preferred connection diagram according to the pseudo-differential audio frequency input circuit of the embodiment of the invention.
Embodiment
Embodiment 1
Fig. 2 is that example shows the pseudo-differential audio frequency input circuit according to the embodiment of the invention with the ear microphone.As shown in Figure 2, the pseudo-differential audio frequency input circuit according to the embodiment of the invention comprises:
1) first path and the alternate path that link to each other with audio input port;
2) be arranged on High-frequency Interference filtering parts on described first path and the described alternate path, be used for that the filtering high frequency differential mode is disturbed and the high frequency common mode interference; Preferably, High-frequency Interference filtering parts comprise: filter capacitor C3, C4, C5, capacitance C1, C2;
3) be connected to the voltage regulator components of described first path and described alternate path, be used to make bias voltage on described first path to equal bias voltage on the described alternate path; Preferably, voltage regulator components comprises: two pull-up resistor R1, R2, the resistance R 3 of simulation ear microphone negative terminal impedance;
4) audio output port that links to each other with described first path, preferred, audio output port is an earphone interface.
In this preferred embodiment, by the voltage regulator components that in difference channel, is provided with, be used to make two bias voltages on the path to equate, solved and to have eliminated the problem of common mode disturbances in the prior art, and then reached the effect that improves audio transmission and store quality.
Preferably, can also comprise in the embodiment shown in Figure 2: the inductance L 1 of voice-frequency channel incoming end (ear microphone anode).Certainly, the present invention is not limited only to this, and inductance L 1 is optional.
The effect of each parts in the circuit shown in Figure 2 is below described:
1) inductance L 1, is used to isolate the extraneous direct current interference and the preliminary isolation of noise;
2) resistance R 1, R2 is respectively the biasing resistor of pseudo-differential two voice-frequency channels, two resistance are received same bias voltage, the internal resistance of ear microphone is generally 2.2k ohm, for the audio signal that makes microphone generating obtains maximum distortionless effect, the clamping of audio frequency input channel at 1/2nd bias voltages, is got R1, and R2 is 2.2k ohm;
3) C4, C3, the C5 filter capacitor, C3, C5 mainly plays the high frequency differential mode of a certain frequency range of filtering and disturbs, and the high frequency common mode of a certain frequency range of the main filtering of C4 is disturbed, and is mainly the common mode disturbances of 900MHz;
4) capacitor C 1, and C2 mainly is the DC level that is used to isolate on the audio signal path, and what the present invention mainly paid close attention to is the common mode disturbances of low frequency, mainly is low frequency signal because people's ear can hear;
5) resistance R 3, regulate the bias voltage on the audio signal path, and two path bias voltages are equated; Preferably, described R3 is an adjustable resistance.
The implementation method of circuit: as shown in Figure 2,
Step S1, by two biasing resistor R1, R2 is connected respectively to same bias supply with audio signal two paths;
Step S2 in working order down, measures the level at test1 place, obtains voltage v1;
Step S3 in working order down, measures the level at test2 place, obtains voltage v2;
Step S4, the resistance of adjustment resistance R 3, the partial pressure value at change v2 place, the level up to the test2 place equals the level at test1 place;
Like this, after being subjected to common mode noise signal s interference on the two-way audio path, noise becomes v1*s and v2*s, v1*s-v2*s=when two paths of signals subtracts each other as difference (v1-v2) s is because v1 is identical with the v2 level, so the result is 0, promptly eliminate common mode disturbances, improved the signal quality of audio frequency.
In this preferred embodiment, by two resistance R 1, R2 moves the two-way audio signal to same bias voltage on, 2, on the voice-frequency channel that does not have the audio signal input (alternate path), an external resistance R 3, purpose are to make the test1 place level on the voice-frequency channel (first path) of audio signal input to equate with test2 place level on the alternate path, utilize differential principle elimination common mode disturbances.In addition, because the circuit in this preferred embodiment can be removed the low frequency common mode disturbances at audio input end with differential signal, so can save the big electric capacity of common mode filtering.
Embodiment 2
The present invention can also be applicable to the situation of monomer microphone input, and as shown in Figure 3, pseudo-differential audio frequency input circuit comprises: first path and the alternate path that link to each other with audio input port; Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb; Be connected to the voltage regulator components of described first path and described alternate path, be used to make bias voltage on described first path to equal bias voltage on the described alternate path; The audio output port that links to each other with described first path.
Preferably, described voltage regulator components comprises: the first biasing resistor R1, be connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node; The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node; Adjust resistance R 3, be connected between described alternate path and the ground, wherein, the tie point of described R3 and described alternate path is described second connected node; Wherein, the resistance between described R1, R2 and the R3 is closed and is: the resistance relation by described R1, R2 and R3 makes the voltage at the described first connected node place equate with the voltage at the described second connected node place.
Preferably, described R3 is an adjustable resistance.
Preferably, pseudo-differential audio frequency input circuit also comprises: isolated part, be connected between described first path and the described audio output port, and be used to isolate extraneous direct current and disturb and noise.
Preferably, described isolated part is an inductance L 1, is connected between described first connected node and the described audio output port.
Preferably, described High-frequency Interference filtering parts comprise: first capacitor C 1, be connected on described first path, and be used for isolated DC; Second capacitor C 2 is connected on the described alternate path, is used for isolated DC; The 3rd capacitor C 3, one ends link to each other with described C1, the other end with link to each other describedly, be used for the filtering high frequency differential mode and disturb; The 4th capacitor C 4 is connected across between described first path and the described alternate path, and an end is connected to described C1 and C3, and the other end is connected to described C2, is used for the filtering high frequency common mode and disturbs; The 5th capacitor C 5, one ends are connected to described C2 and described C4, and the other end links to each other with ground, are used for the filtering high frequency differential mode and disturb.
It is basic identical that circuit structure shown in Figure 3 and operation principle and embodiment 1 described ear microphone are imported, and do not repeat them here.Because the present invention can apply in the circuit of mobile phone monomer microphone input, therefore, can play the effect of difference equally on mobile phone terminal, can also reduce cost simultaneously.
Embodiment 3
The present invention also protects a kind of method to set up of pseudo-differential audio frequency input circuit, and wherein, described circuit comprises: first path and the alternate path that link to each other with audio input port; Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb; Be connected to the voltage regulator components of described first path and described alternate path; The audio output port that links to each other with described first path; Described method comprises: regulate described voltage regulator components so that the bias voltage on described first path equals the bias voltage on the described alternate path.
In this preferred embodiment, by the voltage regulator components that in difference channel, is provided with, be used to make two bias voltages on the path to equate, solved and to have eliminated the problem of common mode disturbances in the prior art, and then reached the effect that improves audio transmission and store quality.
Preferably, described voltage regulator components comprises: the first biasing resistor R1, be connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node; The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node; Adjust resistance R 3, be connected between described alternate path and the ground; Wherein, regulate described voltage regulator components so that the bias voltage on described first path equals the step of the bias voltage on the described alternate path comprises: the voltage of value up to the described first connected node place of regulating described R3 equates with the voltage at the described second connected node place.
Preferably, said method also comprises: between described first path and described audio output port isolated part is set, is used to isolate extraneous direct current and disturbs and noise.
Preferably, comprise in the step that isolated part is set between described first path and the described audio output port: between described first connected node and described audio output port, inductance L 1 is set.
Obviously, those skilled in the art should be understood that, above-mentioned each module of the present invention or each step can realize with the general calculation device, they can concentrate on the single calculation element, perhaps be distributed on the network that a plurality of calculation element forms, alternatively, they can be realized with the executable program code of calculation element, thereby, they can be stored in the storage device and carry out by calculation element, and in some cases, can carry out step shown or that describe with the order that is different from herein, perhaps they are made into each integrated circuit modules respectively, perhaps a plurality of modules in them or step are made into the single integrated circuit module and realize.Like this, the present invention is not restricted to any specific hardware and software combination.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a pseudo-differential audio frequency input circuit is characterized in that, comprising:
First path and the alternate path that link to each other with audio input port;
Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb;
Be connected to the voltage regulator components of described first path and described alternate path, be used to make bias voltage on described first path to equal bias voltage on the described alternate path;
The audio output port that links to each other with described first path.
2. pseudo-differential audio frequency input circuit according to claim 1 is characterized in that described voltage regulator components comprises:
The first biasing resistor R1 is connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node;
The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node;
Adjust resistance R 3, be connected between described alternate path and the ground, wherein, the tie point of described R3 and described alternate path is described second connected node;
Wherein, the resistance between described R1, R2 and the R3 is closed and is: the resistance relation by described R1, R2 and R3 makes the voltage at the described first connected node place equate with the voltage at the described second connected node place.
3. pseudo-differential audio frequency input circuit according to claim 2 is characterized in that described R3 is an adjustable resistance.
4. pseudo-differential audio frequency input circuit according to claim 1 and 2 is characterized in that, also comprises:
Isolated part is connected between described first path and the described audio output port, is used to isolate extraneous direct current and disturbs and noise.
5. pseudo-differential audio frequency input circuit according to claim 4 is characterized in that described isolated part is an inductance L 1, is connected between described first connected node and the described audio output port.
6. pseudo-differential audio frequency input circuit according to claim 1 is characterized in that, described High-frequency Interference filtering parts comprise:
First capacitor C 1 is connected on described first path, is used for isolated DC;
Second capacitor C 2 is connected on the described alternate path, is used for isolated DC;
The 3rd capacitor C 3, one ends link to each other with described C1, the other end with link to each other describedly, be used for the filtering high frequency differential mode and disturb;
The 4th capacitor C 4 is connected across between described first path and the described alternate path, and an end is connected to described C1 and C3, and the other end is connected to described C2, is used for the filtering high frequency common mode and disturbs;
The 5th capacitor C 5, one ends are connected to described C2 and described C4, and the other end links to each other with ground, are used for the filtering high frequency differential mode and disturb.
7. the method to set up of a pseudo-differential audio frequency input circuit is characterized in that, described circuit comprises: first path and the alternate path that link to each other with audio input port; Be arranged on the High-frequency Interference filtering parts on described first path and the described alternate path, be used for interference of filtering high frequency differential mode and high frequency common mode and disturb; Be connected to the voltage regulator components of described first path and described alternate path; The audio output port that links to each other with described first path;
Described method comprises:
Regulate described voltage regulator components so that the bias voltage on described first path equals the bias voltage on the described alternate path.
8. method according to claim 7 is characterized in that, described voltage regulator components comprises: the first biasing resistor R1, be connected between described first path and the bias voltage, and wherein, the tie point of described R1 and described first path is first connected node; The second biasing resistor R2 is connected between described alternate path and the described bias voltage, and wherein, the tie point of described R2 and described alternate path is second connected node; Adjust resistance R 3, be connected between described alternate path and the ground;
Wherein, regulate described voltage regulator components so that the bias voltage on described first path equals the step of the bias voltage on the described alternate path comprises:
The voltage of value up to the described first connected node place of regulating described R3 equates with the voltage at the described second connected node place.
9. according to claim 7 or 8 described methods, it is characterized in that, also comprise: between described first path and described audio output port, isolated part is set, is used to isolate extraneous direct current and disturbs and noise.
10. method according to claim 9 is characterized in that, the step that isolated part is set between described first path and described audio output port comprises:
Between described first connected node and described audio output port, inductance L 1 is set.
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| CN201010561685.9A CN102026063B (en) | 2010-11-26 | 2010-11-26 | Pseudo differential audio input circuit and installation method thereof |
| PCT/CN2011/082624 WO2012068985A1 (en) | 2010-11-26 | 2011-11-22 | Pseudo-differential audio input circuit and arrangement method therefor |
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| CN201010561685.9A CN102026063B (en) | 2010-11-26 | 2010-11-26 | Pseudo differential audio input circuit and installation method thereof |
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| WO2012068985A1 (en) * | 2010-11-26 | 2012-05-31 | 中兴通讯股份有限公司 | Pseudo-differential audio input circuit and arrangement method therefor |
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| CN107820160A (en) * | 2017-09-30 | 2018-03-20 | 深圳市艾特智能科技有限公司 | Signal input circuit |
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| WO2012068985A1 (en) * | 2010-11-26 | 2012-05-31 | 中兴通讯股份有限公司 | Pseudo-differential audio input circuit and arrangement method therefor |
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| CN109275071A (en) * | 2018-11-06 | 2019-01-25 | 珠海市杰理科技股份有限公司 | Apparatus for processing audio, chip, system and method |
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| WO2023010667A1 (en) * | 2021-07-31 | 2023-02-09 | 展讯通信（上海）有限公司 | Electronic apparatus capable of improving output performance of earphones |
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|---|---|
| CN102026063B (en) | 2014-12-10 |
| WO2012068985A1 (en) | 2012-05-31 |
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