CN105992098B - Audio input circuit and electronic terminal - Google Patents
Audio input circuit and electronic terminal Download PDFInfo
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- CN105992098B CN105992098B CN201510050056.2A CN201510050056A CN105992098B CN 105992098 B CN105992098 B CN 105992098B CN 201510050056 A CN201510050056 A CN 201510050056A CN 105992098 B CN105992098 B CN 105992098B
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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
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Abstract
The invention provides an audio input circuit and an electronic terminal, wherein the audio input circuit comprises: the audio acquisition unit is used for acquiring audio signals; the audio sampling unit is used for sampling the audio signals collected by the audio collecting unit and comprises a first audio input end and a second audio input end; the audio acquisition unit is connected with the first audio input end through a first line; the bias voltage providing unit comprises a bias voltage input end, a first output end and a second output end, wherein the first output end and the second output end are respectively connected with the bias voltage input end, the first output end is connected to the first circuit, the second output end is connected to the second audio input end through a second circuit, the voltage of the second output end is equal to the bias voltage input by the bias voltage input end, and the voltage of the first output end is equal to the difference value between the bias voltage input by the bias voltage input end and the audio signal voltage. The scheme of the invention can improve the conversation quality of the electronic terminal.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to an audio input circuit and an electronic terminal.
Background
For a mobile phone board, when a printed circuit board PCB is designed, due to poor layout or wiring problems, a certain impedance exists between different areas of a ground reference plane, a Burst large current demand is generated by the open numerical control system GSM PA high-power transmission of a global mobile communication system, and the large current must flow back to the negative electrode of a battery through the ground reference plane (equivalent to an impedance), and a certain voltage drop is generated when the current flows through the impedance. When the audio return path also uses this path, this voltage drop is superimposed on the audio signal, thereby causing conducted interference with the audio signal. As shown in fig. 1, if the return of the audio circuit traverses the return path of the GSM PA to the battery connection, the audio signal creates conducted interference that results in noise.
The microphone input circuits are of three types, one is a fully differential input circuit, the other is a pseudo differential input circuit, and the other is a single-ended input circuit. The Microphone MEMS Microphone for hand-held call or the electret Microphone ECM Microphone for earphone call is single-ended output. In order to avoid the problem of poor anti-interference capability of a single-ended audio input circuit, the prior art is designed into a pseudo-differential circuit, and a voltage regulating component connected with the ground is arranged on the circuit, so that the problem of common-mode interference is solved. However, the voltage regulation component is usually located in the area of the rf return path from the GSM PA to the battery connector, in which case Noise on the ground, especially Burst/TDMA/TDD Noise, will be coupled to the audio path through the voltage regulation component and thus sampled by the audio input port, resulting in Noise being heard by the other party during the call, affecting the transmission quality of the audio and the satisfaction of the user experience.
Disclosure of Invention
The invention provides an audio input circuit and an electronic terminal, and aims to solve the problem that the transmission quality of audio in the existing audio input circuit of the electronic terminal is poor.
In order to solve the above technical problem, an embodiment of the present invention provides an audio input circuit, including:
the audio acquisition unit is used for acquiring audio signals;
the audio sampling unit is used for sampling the audio signals collected by the audio collecting unit and comprises a first audio input end and a second audio input end; the audio acquisition unit is connected with the first audio input end through a first line;
the bias voltage providing unit comprises a bias voltage input end, a first output end and a second output end, wherein the first output end and the second output end are respectively connected with the bias voltage input end, the first output end is connected to the first circuit, the second output end is connected to the second audio input end through a second circuit, the voltage of the second output end is equal to the bias voltage input by the bias voltage input end, and the voltage of the first output end is equal to the difference value between the bias voltage input by the bias voltage input end and the audio signal voltage.
Wherein the bias voltage providing unit further includes:
a first resistor and a second resistor;
wherein the first output terminal is connected to the bias voltage input terminal through the first resistor; the second output terminal is connected to the bias voltage input terminal through the second resistor.
Wherein the audio input circuit further comprises:
a first capacitor, one end of which is connected to the first line, and a connection end connected to the first line is located between the connection end of the first output end and the first line and the first audio input end, and the other end of which is grounded;
one end of the second capacitor is connected to the second line, the connecting end connected with the second line is positioned between the second output end and the connecting end of the second line and the second audio output end, and the other end of the second capacitor is grounded;
and the third capacitor is bridged between the first line and the second line, one end of the third capacitor is connected to the first capacitor, and the other end of the third capacitor is connected to the second capacitor.
Wherein the first line includes:
and one end of the fourth capacitor is connected with the first capacitor, and the other end of the fourth capacitor is connected with the first audio input end.
Wherein, include on the second circuit:
and one end of the fifth capacitor is connected with the third capacitor, and the other end of the fifth capacitor is connected with the second audio input end.
Wherein, still include on the first line:
and one end of the inductive element is connected with the audio acquisition unit, and the other end of the inductive element is connected with the first output end.
Wherein, the audio acquisition unit is also connected with the ground through a third line.
In order to solve the above technical problem, an embodiment of the present invention further provides an electronic terminal, which includes the audio input circuit as described above.
The technical scheme of the invention has the following beneficial effects:
according to the scheme of the invention, the first output end is connected to the first line, the second output end is connected to the second line, so that the voltage of the second output end is the bias voltage provided by the bias voltage providing unit, and the voltage of the first output end is the difference value between the bias voltage and the audio signal voltage during conversation. The difference value between the voltage of the first output end and the voltage of the second output end is the audio signal voltage and is irrelevant to the bias voltage. When the audio signal is taken as an effective signal and sampled by the audio sampling unit, the bias voltage is selected as the reference voltage, so that the radio frequency conducted interference caused by sharing a radio frequency backflow path is avoided, the transmission quality of the audio signal is greatly improved, and the experience satisfaction degree of a user is improved.
Drawings
FIG. 1 is a diagram showing a layout of components within an electronic terminal;
FIG. 2 is a first schematic circuit diagram of an audio input circuit according to the present invention;
FIG. 3 is a schematic diagram of a second exemplary embodiment of an audio input circuit;
FIG. 4 is a schematic diagram of a third exemplary embodiment of an audio input circuit;
FIG. 5 is a schematic diagram of an audio input circuit according to the present invention;
fig. 6 is a schematic diagram showing a circuit configuration of the audio input circuit according to the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The audio input circuit of the present invention, as shown in fig. 2, mainly includes: the device comprises an audio acquisition unit, an audio sampling unit, a bias voltage providing unit, a first circuit and a second circuit.
Wherein, the audio acquisition unit can be a microphone or an earphone.
The signal transmission and connection relationship among the components in the audio input circuit will be described in detail with reference to fig. 3.
In the first embodiment of the present invention, the audio capturing unit is a microphone, but the audio capturing unit is not limited thereto, and may also be an earphone. The audio acquisition unit mainly has the function of acquiring audio signals; the audio sampling unit MICAMP mainly functions to sample audio signals collected by the audio collecting unit, and includes a first audio input end MicP and a second audio input end MicN; the audio acquisition unit is connected with the first audio input end MicP through a first line.
The bias voltage providing unit in the audio input circuit comprises a bias voltage input end, a first output end and a second output end, wherein the first output end and the second output end are respectively connected with the bias voltage input end; the first output end is connected to the first circuit, and a connecting end formed by connecting the first output end and the first circuit is called a first connecting end; the second output terminal is connected to the second audio input terminal MicN of the audio sampling unit through a second line, and a connection terminal formed by connecting the second output terminal to the second line is referred to as a second connection terminal. In this embodiment, the bias voltage providing unit further includes: a first resistor R1 and a second resistor R2. The first output terminal is connected to the bias voltage input terminal through the first resistor R1, and the second output terminal is connected to the bias voltage input terminal through the second resistor R2.
Referring to fig. 3, the voltage at the second output terminal is a constant voltage (in this embodiment of the present invention, an offset voltage), and during a call, an ac current flowing through the microphone due to the fluctuation of the sound signal, i.e., an audio signal current, is generated due to the presence of the first resistor R1, so that the voltage at the first output terminal is a voltage obtained by superimposing an audio signal voltage on the constant voltage. The difference value between the voltage of the first output end and the voltage of the second output end is the signal sampled by the audio sampling unit, the signal is the audio signal, and the bias voltage is selected as the reference voltage when the audio signal is taken as an effective signal and sampled by the audio sampling unit, so that the radio frequency conducted interference caused by sharing a radio frequency backflow path is avoided.
The foregoing is a detailed description of the connection relationship between some components of the audio input circuit in the first embodiment of the present invention, and certainly in order to make the circuit more complete, that is, in consideration of the existence of other interference in the circuit, such as a high-frequency common mode interference problem, a high-frequency differential mode interference problem, and the like, in the second embodiment of the present invention, as shown in fig. 4, the audio input circuit further includes:
the filter mainly comprises a first capacitor C1, a second capacitor C2 and a third capacitor C3, wherein the three capacitors are combined filter capacitors and mainly filter noises of 900HZ or 2100HZ high-frequency bands of GSM. The position relation of the three capacitors in the audio input circuit is described as follows:
the first capacitor C1 is connected to the first line, and the connection end connected to the first line is referred to as the third connection end. The third connection terminal is located between the first connection terminal and the MicP, and the other end of the first capacitor C1 is grounded.
The second capacitor C2 is connected to the second line, and the connection end formed by connecting the second line is referred to as a fourth connection end. The fourth connection terminal is located between the second connection terminal and the MicN, and the other end of the second capacitor C2 is grounded.
The first capacitor C1 and the second capacitor C2 mainly function to filter the common mode interference in the high frequency band. The third capacitor C3 is connected between the first line and the second line, and has one end connected to the first capacitor C1 and the other end connected to the second capacitor C2. The third capacitor C3 mainly functions to filter out the high-frequency differential mode interference.
In order to isolate the direct current signal on the audio signal path, the direct current signal is prevented from entering the audio sampling unit. In a third embodiment of the present invention, as shown in fig. 5, the audio input circuit of the present invention includes, on the first line: one end of the fourth capacitor C4 is connected to the first capacitor C1, and the other end is connected to the MicP.
The audio input circuit of the present invention comprises on the second line: one end of the fifth capacitor C5 is connected to the second capacitor C2, and the other end is connected to the MicN.
The fourth capacitor C4 and the fifth capacitor C5 mainly function to isolate the dc signal on the audio signal path and prevent the dc signal from entering the audio sampling unit.
In order to isolate external direct current interference and noise, in a fourth embodiment of the present invention, as shown in fig. 6, the first circuit further includes: and one end of the inductance element L is connected with the microphone, and the other end of the inductance element L is connected with the first output end. Of course the microphone is also connected to ground via a third line.
The above is a detailed description of the circuit configuration of the audio input circuit of the present invention, and the following explanation of the principle of the present invention based on the circuit configuration of the audio input circuit of the present invention is as follows:
the main principle of the circuit structure of the audio input circuit of the invention is as follows: the difference value between the voltage of the first output end and the voltage of the second output end is the audio signal voltage and is irrelevant to the bias voltage. The principle of the present invention is explained by way of example based on the circuit configuration of the audio input circuit of the present invention as follows:
the microphone is used as a two-terminal device, and the current flowing through the microphone is assumed to be I ═ I0+ i; wherein, I0Which may be understood as a dc bias current or may be interpreted as a current through the microphone in quiet conditions without sound, which may be considered constant. And i is the alternating current through the microphone caused by the fluctuation of the sound signal during the call. Neglecting the effect of PF stage capacitance and magnetic bead for filtering in the circuit, the coupling input end of the microphone can be regarded as infinite input impedance of an ideal amplifier, and the effect on the circuit can also be not considered. In this way, the voltage expressions of the first output terminal and the second output terminal can be obtained:
voltage V of the first output terminal+＝Vmicbias-R1(I0+i)；
Voltage V of the second output terminal-＝Vmicbias(ii) a Wherein VmicbiasIs a bias voltage.
Because the fourth capacitor C4 and the fifth capacitor C5 exist, the voltage sampled by the audio sampling unit is R1 × i, because the voltage of the second output terminal is a bias voltage, that is, a constant voltage value, the voltage of the first output terminal is a voltage obtained by superimposing an audio signal on the constant voltage value, the difference between the two is an audio signal, and the bias voltage is selected as a reference voltage when the audio signal is sampled by the audio sampling unit as an effective signal, thereby avoiding the radio frequency conducted interference introduced by sharing a radio frequency return path. Compared with the prior art, a voltage regulating component connected with the ground is not needed, and noise on the ground is prevented from being coupled to an audio channel through the voltage regulating component. Meanwhile, because the bias voltage has ripples, if ripple noise exists at the MicP end and the MicN end, the noise is subtracted from the output end of the differential amplifier after the noise enters the audio sampling unit, so that the signal-to-noise ratio is improved.
In conclusion, the scheme of the invention improves the conversation quality of the electronic terminal.
Embodiments of the present invention also provide an electronic terminal including the audio input circuit as described above.
It should be noted that, the electronic terminal is an electronic terminal including the audio input circuit, and the implementation manner of the embodiment of the audio input circuit is applicable to the embodiment of the electronic terminal, and the same technical effect can be achieved.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (6)
1. An audio input circuit, comprising:
the audio acquisition unit is used for acquiring audio signals;
the audio sampling unit is used for sampling the audio signals collected by the audio collecting unit and comprises a first audio input end MicP and a second audio input end MicN; the audio acquisition unit is connected with the first audio input end through a first line; the audio input circuit comprises on a first line: one end of the fourth capacitor C4 is connected with the first capacitor C1, and the other end of the fourth capacitor C4 is connected with the first audio input end MicP; the second line of the audio input circuit comprises: a fifth capacitor C5, one end of which is connected to the second capacitor C2 and the other end of which is connected to the second audio input MicN; the fourth capacitor C4 and the fifth capacitor C5 are used for isolating the direct current signal on the audio signal path and preventing the direct current signal from entering the audio sampling unit; the fourth capacitor C4 and the fifth capacitor C5 are arranged so that the voltage sampled by the audio sampling unit is R1 × i, the voltage of the second output terminal is offset voltage and is a constant voltage value, the voltage of the first output terminal is the voltage of an audio signal superimposed on the constant voltage value, and the difference value of the two is the audio signal;
the bias voltage providing unit comprises a bias voltage input end, a first output end and a second output end, wherein the first output end and the second output end are respectively connected with the bias voltage input end, the first output end is connected to the first circuit, the second output end is connected to the second audio input end through a second circuit, the voltage of the second output end is equal to the bias voltage input by the bias voltage input end, and the voltage of the first output end is equal to the difference value between the bias voltage input by the bias voltage input end and the audio signal voltage.
2. The audio input circuit of claim 1, wherein the bias voltage providing unit further comprises:
a first resistor and a second resistor;
wherein the first output terminal is connected to the bias voltage input terminal through the first resistor; the second output terminal is connected to the bias voltage input terminal through the second resistor.
3. The audio input circuit of claim 1, further comprising:
a first capacitor, one end of which is connected to the first line, and a connection end connected to the first line is located between the connection end of the first output end and the first line and the first audio input end, and the other end of which is grounded;
one end of the second capacitor is connected to the second line, the connecting end connected with the second line is positioned between the connecting end of the second output end and the second line and the second audio input end, and the other end of the second capacitor is grounded;
and the third capacitor is bridged between the first line and the second line, one end of the third capacitor is connected to the first capacitor, and the other end of the third capacitor is connected to the second capacitor.
4. The audio input circuit of claim 1, further comprising on the first line:
and one end of the inductive element is connected with the audio acquisition unit, and the other end of the inductive element is connected with the first output end.
5. The audio input circuit of claim 1, wherein the audio capture unit is further connected to ground via a third line.
6. An electronic terminal, characterized in that it comprises an audio input circuit according to any one of claims 1 to 5.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510050056.2A CN105992098B (en) | 2015-01-30 | 2015-01-30 | Audio input circuit and electronic terminal |
| PCT/CN2015/091679 WO2016119487A1 (en) | 2015-01-30 | 2015-10-10 | Audio input circuit and electronic terminal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510050056.2A CN105992098B (en) | 2015-01-30 | 2015-01-30 | Audio input circuit and electronic terminal |
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| CN105992098A CN105992098A (en) | 2016-10-05 |
| CN105992098B true CN105992098B (en) | 2020-03-10 |
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| CN201510050056.2A Active CN105992098B (en) | 2015-01-30 | 2015-01-30 | Audio input circuit and electronic terminal |
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| WO (1) | WO2016119487A1 (en) |
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| CN112153182B (en) * | 2019-06-28 | 2022-04-19 | 西安中兴新软件有限责任公司 | Audio circuit and mobile terminal with same |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101175101A (en) * | 2006-11-02 | 2008-05-07 | 联想移动通信科技有限公司 | Sound processing method and device for mobile phone microphone |
| CN201307878Y (en) * | 2008-11-05 | 2009-09-09 | 宇龙计算机通信科技(深圳)有限公司 | Analog audio input circuit, mobile communication terminal and earphone |
| CN102026063A (en) * | 2010-11-26 | 2011-04-20 | 中兴通讯股份有限公司 | Pseudo differential audio input circuit and installation method thereof |
| CN203788450U (en) * | 2014-04-18 | 2014-08-20 | 青岛海信移动通信技术股份有限公司 | Current hum restraining circuit of mobile terminal and mobile terminal |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7882743B2 (en) * | 2005-12-20 | 2011-02-08 | Broadcom Corp. | Method and system for noise dosimeter |
| US20110018616A1 (en) * | 2009-07-22 | 2011-01-27 | Kontel Data System Limited | Charge pump circuit |
| CN201479352U (en) * | 2009-07-29 | 2010-05-19 | 比亚迪股份有限公司 | Audio adjusting circuit of earphone sender |
| CN103731776A (en) * | 2012-10-15 | 2014-04-16 | 成都众易通科技有限公司 | Audio circuit used for GPS voice control system |
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2015
- 2015-01-30 CN CN201510050056.2A patent/CN105992098B/en active Active
- 2015-10-10 WO PCT/CN2015/091679 patent/WO2016119487A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101175101A (en) * | 2006-11-02 | 2008-05-07 | 联想移动通信科技有限公司 | Sound processing method and device for mobile phone microphone |
| CN201307878Y (en) * | 2008-11-05 | 2009-09-09 | 宇龙计算机通信科技(深圳)有限公司 | Analog audio input circuit, mobile communication terminal and earphone |
| CN102026063A (en) * | 2010-11-26 | 2011-04-20 | 中兴通讯股份有限公司 | Pseudo differential audio input circuit and installation method thereof |
| CN203788450U (en) * | 2014-04-18 | 2014-08-20 | 青岛海信移动通信技术股份有限公司 | Current hum restraining circuit of mobile terminal and mobile terminal |
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| Publication number | Publication date |
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| WO2016119487A1 (en) | 2016-08-04 |
| CN105992098A (en) | 2016-10-05 |
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