CN114827831A - Pseudo-differential audio input circuit and apparatus - Google Patents
Pseudo-differential audio input circuit and apparatus Download PDFInfo
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- CN114827831A CN114827831A CN202110117327.7A CN202110117327A CN114827831A CN 114827831 A CN114827831 A CN 114827831A CN 202110117327 A CN202110117327 A CN 202110117327A CN 114827831 A CN114827831 A CN 114827831A
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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
- H04R3/02—Circuits for transducers, loudspeakers or microphones for preventing acoustic reaction, i.e. acoustic oscillatory feedback
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Abstract
The invention relates to a pseudo-differential audio input circuit and a device, wherein the circuit comprises a microphone audio negative input port, a microphone audio positive input port, an audio negative output interface, an audio positive output interface, a bias resistor and a filter capacitor; the microphone audio negative input port is connected with the audio negative output interface and is grounded; one end of the filter capacitor is connected with the bias resistor, and the other end of the filter capacitor is grounded; the microphone audio positive input port is connected with the bias resistor; the audio positive output interface is respectively connected with the bias resistor and the microphone audio positive input interface. Therefore, the differential negative input end and the filter capacitor grounding end are connected to the audio input interface grounding end in a wiring mode, reference grounds at the positive end and the negative end of the differential signal are balanced, common mode interference and high frequency interference on a PCB are removed, and transmission quality of the audio analog signal is improved.
Description
Technical Field
The invention belongs to the technical field of audio processing, and particularly relates to a pseudo-differential audio input circuit and a pseudo-differential audio input device.
Background
In the existing audio pseudo-differential input circuit, because reference ground potentials at the positive end and the negative end of pseudo-differential analog signal input are different, noise signals can be brought, and the transmission quality of the signals is greatly influenced.
For the situation, the pseudo-differential analog signal input circuit in the prior art has two connection modes, the first is that the negative input end is grounded, signals enter a link from the positive input end, interference is introduced due to imbalance of differential signals, the quality of audio signals is affected, and the second is that a filter circuit is added at the input end, so that the quality of the signals can be improved, but the cost is increased.
Disclosure of Invention
In order to solve the problems of noise floor and interference of audio pseudo-differential input of an audio pseudo-differential input circuit in the prior art, the specific embodiment of the application provides a pseudo-differential audio input circuit and a device;
in a first aspect, an embodiment of the present application provides a pseudo-differential audio input circuit, including;
the microphone audio negative input port, the microphone audio positive input port, the audio negative output interface, the audio positive output interface, the bias resistor and the filter capacitor;
the microphone audio negative input port is connected with the audio negative output interface and is grounded;
one end of the filter capacitor is connected with the bias resistor, and the other end of the filter capacitor is grounded;
the microphone audio positive input port is connected with the bias resistor;
the audio positive output interface is respectively connected with the bias resistor and the microphone audio positive input interface.
Optionally, the system further comprises a bias voltage interface;
the bias voltage interface is respectively connected with the filter capacitor and the bias resistor and is used for connecting an external bias power supply.
Optionally, the audio negative output interface is connected to the microphone audio negative input port through a first isolation capacitor, and is grounded through the first isolation capacitor.
Optionally, the audio positive output interface is connected to the microphone audio positive input interface through a second isolation capacitor, and is connected to the bias resistor through the second isolation capacitor.
Optionally, the device further comprises an audio seat;
one end of the audio seat is connected with the microphone audio positive input port, and the other end of the audio seat is grounded.
Optionally, the resistance of the bias resistor is the same as the internal resistance of the external microphone.
Optionally, the resistance of the bias resistor is 2.2K ohms.
Optionally, the first isolation capacitor and the second isolation capacitor are close to the audio output end;
and the ground end of the filter capacitor of the bias voltage and the audio negative input port of the microphone are connected to the ground port of the audio seat through lines.
In a second aspect, an embodiment of the present application provides a pseudo-differential audio input device, including a bottom layer circuit and a top layer circuit;
the top-level circuit comprises the pseudo-differential audio input circuit as described in the embodiment of the present application, and is configured to receive and process an external audio signal;
the bottom layer circuit is a basic audio processing circuit.
Optionally, the system further comprises a transmission processing module;
the transmission processing module is connected with the pseudo-differential audio input circuit and used for receiving and processing the audio signals and sending the processed audio signals to external equipment.
The invention has the beneficial effects that: the pseudo-differential audio input and output circuit comprises a microphone audio negative input port, a microphone audio positive input port, an audio negative output interface, an audio positive output interface, a bias resistor and a filter capacitor; the microphone audio negative input port is connected with the audio negative output interface and is grounded; one end of the filter capacitor is connected with the bias resistor, and the other end of the filter capacitor is grounded; the microphone audio positive input port is connected with the bias resistor; the audio positive output interface is respectively connected with the bias resistor and the microphone audio positive input interface. Therefore, the grounding ends of the differential negative input end and the filter capacitor of the bias power supply are connected to the grounding end of the audio input interface in a wiring mode, so that the reference ground at the positive end and the negative end of the differential signal is balanced, common mode interference and high frequency interference on a PCB (printed circuit board) are removed, the transmission quality of the audio signal is improved, and the problem of high noise in the existing audio input circuit is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art pseudo-differential audio input circuit provided in accordance with an exemplary embodiment;
FIG. 2 is a schematic diagram of a pseudo-differential audio input circuit provided in accordance with an exemplary embodiment;
FIG. 3 is a schematic diagram of a PCB trace of a pseudo-differential audio input circuit provided in accordance with an exemplary embodiment;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
In the prior art, direct current is generally isolated by an isolation capacitor, high-frequency differential mode interference and high-frequency common mode interference are filtered by the capacitor, the bias voltages of two paths are equal by adjusting the resistance value of a bias resistor, and external direct current interference and noise are isolated by an isolation device.
Fig. 1 is a schematic diagram of a prior art pseudo-differential audio input circuit provided in accordance with an exemplary embodiment, such as that of fig. 1, for isolating dc through an isolation capacitor C1 and an isolation capacitor C2; high-frequency differential mode interference is filtered through the capacitor C3 and the capacitor C5; filtering out high-frequency common mode interference through C4; the bias resistors R1, R2 and R3, R3 is an adjustable resistor, and the bias voltages of the two paths can be equal by adjusting the value of the resistor R3; meanwhile, an L1 isolation component is arranged to isolate outside direct current interference and noise.
However, the method has the disadvantages of complex circuit, high cost, calculation of values of all devices and complex process. In view of these technical problems, embodiments of the present application provide a pseudo-differential audio input circuit, which is used to solve corresponding technical problems.
Fig. 2 is a schematic diagram of a pseudo-differential audio input circuit according to an exemplary embodiment, the pseudo-differential audio input circuit according to the present disclosure is configured to receive external audio data, simultaneously eliminate noise and interference, and transmit signals to a device such as a bluetooth chip for further processing by the device such as the bluetooth chip, and the pseudo-differential audio input circuit includes: the microphone audio negative input port, the microphone audio positive input port, the audio negative output interface, the audio positive output interface, the bias resistor and the filter capacitor are included;
the microphone audio negative input port is connected with the audio negative output interface and is grounded; one end of the filter capacitor is connected with the bias resistor, and the other end of the filter capacitor is grounded; the microphone audio positive input port is connected with a bias resistor; the audio positive output interface is respectively connected with the bias resistor and the microphone audio positive input interface.
Specifically, as shown in fig. 2, the microphone audio negative input port is the MIC-port in fig. 1, and the microphone audio positive input port is the MIC + port in fig. 1, and is used for connecting an external microphone and receiving external audio data; in practical application, in order to increase the range of audio input, the interface of the pseudo-differential audio input circuit for audio input further comprises an audio socket J1 in the figure, and is also used for connecting an external audio device to realize the function of audio input. The negative input end of the microphone audio is grounded, and the positive input end of the microphone audio is connected with the audio seat.
One end of a filter capacitor C3 is connected with the bias resistor R1, the other end of the filter capacitor C3 is connected with the Bluetooth chip through a bias voltage interface micbias, bias voltage access is realized, the other end of the filter capacitor C3 is grounded, and the filter capacitor C3 is used for filtering interference brought by a bias power supply; the bias resistor is also connected with a micbias interface, an audio positive output interface micin-p and a microphone audio positive input port MIC + to form a circuit.
In practical application, the bias resistor may be a pull-up resistor, the resistance of the resistor is the same as the internal resistance of the external microphone, and the internal resistance of the microphone is generally 2.2K ohms, so the resistance of the bias resistor R1 may also be 2.2K ohms.
According to the pseudo-differential audio input circuit provided by the embodiment of the application, the grounding ends of the differential negative input end and the filter capacitor of the bias power supply are connected to the grounding end of an audio input interface (a microphone or an audio seat) in a wiring mode, common mode interference and high frequency interference on a PCB (printed circuit board) are removed by balancing reference grounds at the positive end and the negative end of a differential signal, the transmission quality of an audio analog signal is improved, and the problem of high noise in the audio input circuit in the prior art is solved.
Further, according to the pseudo-differential audio input circuit provided by the embodiment of the application, an isolation capacitor C1 is further arranged behind an audio negative output interface, namely micin-n, and an isolation capacitor C2 is further arranged behind an audio positive output interface, namely micin-p, and is used for isolating direct current interference and noise on an audio signal path.
It should be noted that the audio negative output port micin-n, the audio positive output port micin-p, and the bias voltage interface micbias in the pseudo-differential audio input circuit provided in the embodiment of the present application are all used to connect to an external audio processing device, such as a bluetooth chip, a wireless microphone, and the like, for further processing the circuit after the circuit receives and processes the signal.
In addition, fig. 3 is a schematic diagram of a PCB trace of a pseudo differential audio input circuit according to an exemplary embodiment, in the pseudo differential audio input circuit provided in the present application, during circuit layout, as shown in fig. 3, an isolation capacitor C1 and an isolation capacitor C2 are close to an output terminal, and a ground terminal of a filter capacitor C3 of a bias voltage and a negative input port MIC of a microphone audio-GND PIN are connected to a GND PIN of an audio input audio pad J1 through a trace, so that in-band interference of audio can be effectively eliminated.
In practical application, the PCB circuit can have two layers, namely a TOP layer and a BOTTOM layer, the pseudo-differential audio input circuit is arranged on the TOP layer, and related circuits can be arranged on the BOTTOM layer to be matched for use, so that the functions of audio format conversion and audio input are completed.
In addition, the PCB can be used for paving the ground, and the introduced interference can be improved by dividing the audio input and the ground reference of other parts.
The utility model provides a pseudo-differential audio input circuit, be connected to audio input interface promptly microphone or audio frequency seat with the filter capacitor earthing terminal of microphone difference negative input end and bias power through the mode of walking the line, through the reference ground of balanced differential signal positive and negative both ends, get rid of common mode interference and high frequency interference on the PCB circuit board, improve audio frequency analog signal's transmission quality, when effectively removing noise and interference, reduce used electrical components, the circuit is simple, the two-layer range upon range of circuit of PCB just can be realized, and the cost is reduced.
Based on the same inventive concept, the embodiment of the application also provides a pseudo-differential audio output device, which comprises a bottom layer circuit and a top layer circuit;
the top-level circuit comprises a pseudo-differential audio input circuit provided by the above embodiment of the present application, for receiving an external audio signal; the underlying circuit is a basic audio processing circuit, which is a common circuit for audio processing, and is a common means in the field for implementing basic functions of audio processing, such as input, output, and the like, and may be specifically performed with reference to other audio processing devices, and a detailed description thereof is omitted here.
Furthermore, the pseudo-differential audio output device also comprises a transmission processing module;
the transmission processing module is connected with the pseudo-differential audio input circuit, specifically, connected with micin-n, micin-n and micbias ports in the pseudo-differential audio input circuit through a preset port, and configured to receive and process an audio signal, and send the processed audio signal to an external device. In practical application, the transmission processing module may be a bluetooth chip or a wireless microphone, etc.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A pseudo differential audio input circuit is characterized by comprising a microphone audio negative input port, a microphone audio positive input port, an audio negative output interface, an audio positive output interface, a bias resistor and a filter capacitor;
the microphone audio negative input port is connected with the audio negative output interface and is grounded;
one end of the filter capacitor is connected with the bias resistor, and the other end of the filter capacitor is grounded;
the microphone audio positive input port is connected with the bias resistor;
the audio positive output interface is respectively connected with the bias resistor and the microphone audio positive input interface.
2. The pseudo-differential audio input circuit according to claim 1, further comprising a bias voltage interface;
the bias voltage interface is respectively connected with the filter capacitor and the bias resistor and is used for connecting an external bias power supply.
3. A pseudo-differential audio input circuit according to claim 1, wherein the audio negative output port is connected to the microphone audio negative input port through a first isolation capacitor, and is connected to ground through the first isolation capacitor.
4. A pseudo-differential audio input circuit according to claim 3, wherein the audio positive output port is connected to the microphone audio positive input port through a second isolation capacitor, and the bias resistor is connected through the second isolation capacitor.
5. The pseudo-differential audio input circuit according to claim 4, further comprising an audio jack;
one end of the audio seat is connected with the microphone audio positive input port, and the other end of the audio seat is grounded.
6. The pseudo-differential audio input circuit according to claim 1, wherein the bias resistor has the same resistance as the internal resistance of the external microphone.
7. A pseudo-differential audio input circuit according to claim 1, wherein the bias resistor has a resistance of 2.2K ohms.
8. The pseudo-differential audio input circuit according to claim 5,
the first isolation capacitor and the second isolation capacitor are close to the audio output end;
and the filter capacitor of the bias voltage and the audio negative output port are connected to the ground port of the audio seat through lines.
9. A pseudo-differential audio input device is characterized by comprising a bottom layer circuit and a top layer circuit;
the top-level circuit comprises a pseudo-differential audio input circuit as claimed in any one of claims 1 to 8 for receiving and processing an external audio signal;
the bottom layer circuit is a basic audio processing circuit.
10. The pseudo-differential audio input device according to claim 9, further comprising a transmission processing module;
the transmission processing module is connected with the pseudo-differential audio input circuit and used for receiving and processing the audio signals and sending the processed audio signals to external equipment.
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| CN202110117327.7A CN114827831A (en) | 2021-01-28 | 2021-01-28 | Pseudo-differential audio input circuit and apparatus |
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| CN202110117327.7A CN114827831A (en) | 2021-01-28 | 2021-01-28 | Pseudo-differential audio input circuit and apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024088208A1 (en) * | 2022-10-27 | 2024-05-02 | 维沃移动通信有限公司 | Electronic device and electronic device assembly |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2024088208A1 (en) * | 2022-10-27 | 2024-05-02 | 维沃移动通信有限公司 | Electronic device and electronic device assembly |
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