WO2018166271A1 - Fm earphone jack circuit, audio terminal and control method therefor - Google Patents

Abstract

A frequency modulation (FM) earphone jack circuit, an audio terminal and a control method therefor, comprising: connecting an FM signal processing circuit to an earphone interface circuit and an audio codec, introducing an FM signal by means of the earphone interface circuit when the earphone interface circuit is connected to an external earphone, and sending same to the audio codec; the audio codec transmitting, by means of the earphone interface circuit connected thereto, the processed audio signal to the external earphone connected to the earphone interface circuit for playing; an FM circuit and an impedance matching circuit that is connected to the FM circuit in parallel also being connected to the earphone interface circuit, a controller controlling, according to the current operating state of the FM earphone jack circuit, the connection or disconnection between the impedance matching circuit and the FM circuit.

Description

FM earphone base circuit, audio terminal and control method thereof Technical field

Embodiments of the present invention relate to, but are not limited to, the field of electronic circuits, and in particular, an FM (Frequency Modulation) headphone circuit, an audio terminal, and a control method thereof.

Background technique

With the continuous advancement of technology, the running performance of intelligent terminals is also constantly improving. Entertainment has gradually become a very important attribute of intelligent terminals, and music is an important means to increase the entertainment of terminals, due to HIFI (High- Fidelity, high-fidelity audio can truly restore the most pure original music emotions, so HIFI audio is more and more popular and loved by users, especially with Guangdong Opal Mobile Communications Co., Ltd. OPPO smart terminal and Vivo mobile communication limited The rise of the company's VIVO smart terminal, HIFI audio has been pushed to a new peak.

Summary of the invention

The following is an overview of the topics detailed in this document. This Summary is not intended to limit the scope of the claims.

In the actual application scenario, on the one hand, in order to ensure the quality of the HIFI audio on the terminal to enable the user to obtain a better experience, the terminal has a special requirement for the earphone socket circuit, that is, the DC impedance of the earphone socket to the ground is sufficiently small, and the more The smaller the better, the less than 100 milliohms is usually required to ensure HIFI audio. On the other hand, if there is FM demand, in order to ensure the performance of the FM earphone antenna and prevent the FM antenna signal from leaking to the ground, the earphone needs to be guaranteed. The ground impedance of the seat is large enough near the FM operating frequency (86MHz-108MHz). In order to meet the requirements of FM, it is common to connect a magnetic ball with a relatively high impedance between the earphone ground and the motherboard ground. A parallel resonant circuit composed of an inductor and a capacitor), for example, a magnetic bead BEAD1 with an impedance of 500 milliohms is connected in series between the ground of the earphone base and the ground of the main board. In this case, as shown in FIG. 1, L1-L4 are magnetic beads or The inductor is mainly set to isolate the FM signal to prevent the FM signal from leaking to the audio codec. RV1 and RV2 are anti-static devices that can protect the chip at the back end. Capacitors C1 and C2 are mainly set. Filtering the interference signal. In view of the DC impedance of the bead BEAD1 can not meet the HIFI requirements of this DC impedance, this will inevitably affect the HIFI related indicators, which in turn affect the audio output of the headphone socket output.

Referring to FIG. 2, FIG. 2 shows experimental data of the HIFI indicator in two cases, wherein the first case is when the impedance value between the earphone ground and the motherboard ground is close to zero. Obtain the required HIFI audio, but can not meet the needs of FM; the second case is the case where the impedance between the earphone ground and the motherboard ground is 500 milliohms, which can meet the needs of FM, but can not get HIFI audio. According to the relevant experimental data, it can be clearly seen that the second case is about 15 dB worse than the HIFI THD+N (Total Harmonic Distortion+Noise) of the HIFI in the first case, and the crosstalk is deteriorated. The terminal is unable to achieve HIFI and FM compatibility, that is, if the terminal can provide FM function to the user, the terminal cannot provide HIFI audio for the user. If the terminal can provide HIFI audio to the user, the terminal cannot Providing users with FM functions means that they can only choose between HIFI and FM, which affects the user experience.

Embodiments of the present invention provide an FM earphone base circuit, an audio terminal, and a control method thereof.

An embodiment of the present invention provides an FM earphone base circuit, including: a headphone interface circuit, an audio codec, an FM frequency modulation circuit, an FM signal processing circuit, an impedance matching circuit, and a controller;

The earphone interface circuit is connected to the audio codec, and the audio codec transmits the processed audio signal to the external earphone connected to the earphone interface circuit through the earphone interface circuit for playing;

The FM signal processing circuit is respectively connected to the earphone interface circuit and the audio codec, and is configured to introduce an FM signal through the earphone interface circuit and send it to the earphone interface circuit when the earphone interface circuit is connected to the external earphone Audio codec;

The FM frequency modulation circuit is connected to the earphone interface circuit, and the impedance matching circuit is connected in parallel with the FM frequency modulation circuit;

The controller is connected to the control end of the impedance matching circuit, and is configured to control the impedance matching circuit to be turned on or off with the FM frequency modulation circuit according to a current working state of the FM earphone base circuit, the FM The impedance value of the parallel circuit obtained after the frequency modulation circuit is connected in parallel with the impedance matching circuit is less than or equal to the high fidelity impedance threshold.

An embodiment of the present invention further provides an audio terminal, including the FM earphone base circuit described above.

The embodiment of the invention further provides a method for controlling an audio terminal, including:

Obtaining a current working state of the FM earphone base circuit of the audio terminal;

And controlling the impedance matching circuit to be turned on or off from the FM frequency modulation circuit according to a current working state of the FM earphone base circuit.

Embodiments of the present invention provide a computer readable storage medium storing computer executable instructions, which are implemented by a processor to implement the above control method of an audio terminal.

The beneficial effects of the embodiments of the present invention are:

According to the FM earphone base circuit, the audio terminal and the control method thereof, the FM signal processing circuit is respectively connected with the earphone interface circuit and the audio codec, and when the earphone interface circuit is connected with the external earphone, through the earphone interface circuit Introducing an FM signal and transmitting it to the audio codec; the audio codec transmits the processed audio signal to an external earphone connected to the earphone interface circuit through the earphone interface circuit connected thereto; and the FM interface includes a FM The frequency modulation circuit has an impedance matching circuit in parallel with the FM frequency modulation circuit, and a controller is connected to the control end of the impedance matching circuit, and the controller controls the impedance matching circuit to be connected to or disconnected from the FM frequency modulation circuit according to the current working state of the FM earphone socket circuit. The impedance value of the parallel circuit obtained after the FM frequency modulation circuit and the impedance matching circuit are connected in parallel is less than or equal to the high fidelity impedance threshold. Since the controller can control the impedance matching circuit and the FM frequency modulation circuit to be turned on or off, the controller can Control the impedance between the ground wire of the earphone and the ground wire of the motherboard, for example, control The controller can control the impedance matching circuit to be connected to the FM frequency modulation circuit when the current working state is the HIFI audio playing state, and the ground impedance value at this time is small to meet the HIFI requirement, or the controller can also be currently When the working state is the FM working state, the control impedance matching circuit is disconnected from the FM frequency modulation circuit, and the ground impedance at this time is the impedance value of the FM frequency modulation circuit, correspondingly meeting the requirements of the FM, so it is compatible with HIFI and FM. Increased user experience satisfaction.

Other aspects will be apparent upon reading and understanding the drawings and detailed description.

BRIEF abstract

1 is a circuit diagram of an FM earphone base circuit;

Figure 2 is a schematic diagram of high fidelity audio indicators tested in two different situations;

3 is a schematic structural diagram of an FM earphone base circuit according to Embodiment 1 of the present invention;

4 is a schematic diagram of a first circuit of an FM earphone base circuit according to Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram of an internal structure of a switch according to Embodiment 2 of the present invention; FIG.

6 is a schematic diagram of a high-fidelity audio index tested in a high-fidelity audio playing state according to Embodiment 2 of the present invention;

7 is a second circuit diagram of an FM earphone base circuit according to Embodiment 2 of the present invention;

8 is a third circuit diagram of an FM earphone base circuit according to Embodiment 2 of the present invention;

9 is a schematic structural diagram of an audio terminal according to Embodiment 2 of the present invention;

FIG. 10 is a schematic flowchart diagram of a method for controlling an audio terminal according to Embodiment 3 of the present invention.

Embodiments of the invention

The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Embodiment 1:

This embodiment provides an FM earphone base circuit. The FM earphone socket circuit provided in this embodiment can be connected to an external earphone to play audio processed by the FM earphone socket circuit. Referring to FIG. 3, the FM earphone socket provided in this embodiment is provided. The circuit 30 includes a headphone interface circuit 31, an audio codec 32, an FM frequency modulation circuit 33, an FM signal processing circuit 34, an impedance matching circuit 35, and a controller 36.

The earphone interface circuit 31 in this embodiment is connected to the audio codec 32, and the audio codec 32 transmits the processed audio signal to the external earphone connected to the earphone interface circuit 31 through the earphone interface circuit 31 for playing. The audio codec 32 in this embodiment is mainly responsible for the conversion between the analog signal and the digital signal, including converting the digital signal into an analog signal, and converting the analog signal into a digital signal; the FM signal processing circuit 34 and the earphone interface circuit respectively 31 is connected to the audio codec 32, and is arranged to introduce an FM signal through the headphone interface circuit 31 and send it to the audio codec 32 when the headphone interface circuit 31 is connected to the external earphone; the FM frequency modulation circuit 33 is connected to the headphone interface circuit 31, and the impedance The matching circuit 35 is connected in parallel with the FM frequency modulation circuit 33; the controller 36 is connected to the control terminal of the impedance matching circuit 35, and is arranged to control the impedance matching circuit 35 and the FM frequency modulation circuit 33 to be turned on or off according to the current operating state of the FM earphone base circuit 30. When the FM frequency modulation circuit 33 is connected in parallel with the impedance matching circuit 35, the impedance value of the parallel circuit is less than or equal to high fidelity. The impedance threshold, where the high-fidelity threshold is the maximum impedance value that can be obtained by the developer according to the actual situation. The high-fidelity threshold in this embodiment can be 100 milliohms. Of course, the specific value is not limited. The numerical value provided by this embodiment can also take, for example, 90 milliohms, 80 milliohms, and the like.

In an exemplary embodiment, the earphone interface circuit 31 in this embodiment may include an earphone ground circuit, and a left channel interface circuit, a right channel interface circuit, and an FM channel circuit 33 respectively connected to the audio codec 32. The earphone ground circuit is connected, and the audio signal processed by the audio codec 32 can be transmitted to the external earphone connected to the earphone ground circuit through the left channel interface circuit or the right channel interface circuit for playing, and the FM frequency modulation circuit 33 is mainly set. Preventing FM antenna signals from leaking to the ground affects the user's experience with FM. In an exemplary embodiment, the headphone interface circuit 31 also often includes a microphone interface circuit in a practical application scenario, wherein the microphone interface circuit is connected to the audio codec 32, and the sound input from the microphone interface circuit can be passed to the audio codec. The processor 32 performs processing.

In an exemplary embodiment, the FM signal processing circuit 34 in this embodiment is respectively connected to the earphone interface circuit 31 and the audio codec 32, including: one end of the FM signal processing circuit 34 and the earphone ground circuit, and the left channel interface circuit. At least one of the right channel interface circuits is connected to introduce an FM signal when the headphone interface circuit 31 is connected to the external earphone, the other end of the FM signal processing circuit 34 is connected to the audio codec 32, and the FM signal processing circuit 34 is opposite to the slave. The FM signal introduced by the headphone interface circuit 31 is processed, and then the processed signal is passed to the audio codec 32 for processing, and then the audio codec 32 processes the signal and finally transmits it to the earphone through the headphone interface circuit 31. The external headphones connected to the interface circuit 31 are played. In an exemplary embodiment, one end of the FM signal processing circuit 34 in this embodiment may be connected to any one of the earphone grounding circuit, the left channel interface circuit, and the right channel interface circuit, or may be the same as the above three. Any two circuits in the circuit are connected, or may be connected to the above three circuits at the same time. In an exemplary embodiment, when the FM signal processing circuit 34 is connected to the left channel interface circuit or the right channel interface circuit, the left channel interface circuit or the right channel interface may be respectively connected by the FM signal processing circuit 34. A DC blocking capacitor between the circuits introduces an FM signal.

In an exemplary embodiment, the current working state of the FM earphone base circuit 30 in this embodiment includes: a high-fidelity audio playing state and an FM working state; the controller 36 in this embodiment is set to be in the current working state. In the high-fidelity audio playing state, the control impedance matching circuit 35 is turned on by the FM frequency-modulating circuit 33, and when the current operating state is the FM operating state, the control impedance matching circuit 35 is disconnected from the FM frequency-modulating circuit 33. In an exemplary embodiment, since the impedance matching circuit 35 is connected in parallel with the FM frequency modulation circuit 33, when the impedance matching circuit 35 is connected to the FM frequency modulation circuit 33, the impedance value of the impedance matching circuit 35 in parallel with the FM frequency modulation circuit 33 is smaller than The impedance value of any one of the impedance matching circuit 35 and the FM frequency modulation circuit 33. The impedance matching circuit 35 may be any circuit capable of adjusting the parallel equivalent impedance values of the FM frequency modulation circuit 33 and the impedance matching circuit 35, and may include, for example, a switch and a resistor, wherein the switch and the resistor may be connected in series, and the controller 36 may pass The opening or closing of the switch is controlled to control whether the resistor and the FM frequency modulation circuit 33 are turned on; the above resistor may also be any electronic component having a certain impedance value.

In order to make the impedance value of the impedance matching circuit 35 in parallel with the FM frequency modulation circuit 33 sufficiently small to meet the requirements of the high fidelity audio playing state, in an exemplary embodiment, the impedance value of the impedance matching circuit 35 may be equal to the high fidelity impedance threshold. Or, it may be smaller than the high-fidelity impedance threshold. For the FM working state, in order to prevent the FM antenna signal from leaking to the ground, it is necessary to ensure that the impedance of the FM earphone base circuit 30 is sufficiently large (FM operating frequency band), and the impedance matching at this time The circuit 35 is disconnected from the FM frequency modulation circuit 33. The magnitude of the impedance value of the FM frequency modulation circuit 33 is the impedance value of the ground of the FM earphone base circuit 30. Therefore, in the practical application scenario, the FM frequency modulation circuit 33 can be ensured to be large enough (FM operation). Frequency band). In this embodiment, the FM frequency modulation circuit 33 can be implemented in various embodiments. For example, a magnetic bead having a large DC impedance can be selected as the FM frequency modulation circuit 33, or an LC parallel resonant circuit can also be selected as the FM frequency modulation circuit 33. FM signal quality and performance.

In an exemplary embodiment, the current working state of the FM earphone base circuit 30 in this embodiment further includes a normal audio playing state. In some embodiments, the controller 36 may be in a normal audio playing state when the current working state is The control impedance matching circuit 35 is disconnected from the FM frequency modulation circuit 33. In other embodiments, the controller 36 can also control the impedance matching circuit 35 to be connected to the FM frequency modulation circuit 33 when the current operating state is the normal audio playback state. .

In the FM earphone base circuit provided in this embodiment, since the impedance matching circuit and the FM frequency modulation circuit can be controlled to be turned on or off by the controller, the impedance between the earphone ground wire and the motherboard ground wire can be controlled by the controller. It is compatible with HIFI and FM, which improves the satisfaction of the user experience.

Embodiment 2:

In order to facilitate a better understanding, the embodiment is illustrated by a more specific FM earphone base circuit. The FM earphone base circuit in this embodiment includes a headphone interface circuit, an audio codec, an FM frequency modulation circuit, and an FM signal processing circuit. The impedance matching circuit and the controller, wherein the earphone interface circuit comprises an earphone ground circuit A1, a right channel interface circuit A2, a left channel interface circuit A3, an earphone detection interface circuit A4, and a microphone interface circuit A5.

Referring to FIG. 4, FIG. 4 is a schematic diagram of an FM earphone base circuit in an example of the embodiment. The FM frequency modulation circuit in this example is a magnetic bead BEAD1 (0603 package), and the DC impedance of the magnetic bead BEAD1 is 500 millimeters. Europe, and connected to the headphone interface circuit. A magnetic bead is also connected between the earphone interface circuit and the audio codec. Of course, the magnetic bead can also be replaced with an inductor. RV1 and RV2 in this example are anti-static devices that protect the chip at the back end. Capacitors C1 and C2 are primarily configured to filter the interfering signals. The FM signal processing circuit in this example is respectively connected to the headphone interface circuit and the audio codec. When the headphone interface circuit is connected to the external earphone, the FM signal can be sent to the audio codec through the headphone interface circuit, the impedance in this example. The matching circuit can be a switch S1 with a DC impedance of 100 milliohms. The switch can be a switch chip WAS4732 provided by Shanghai Weir Semiconductor Co., Ltd., as shown in FIG. 5, FIG. 5 is an internal structure diagram of the switch chip WAS4732. The switch S1 is connected in parallel with the bead BEAD1, and the VCC pin of the switch S1 is connected to the power supply 37. Among them, the function description of the chip WAS4732 is shown in the following Table 1:

Table I

Logic input (SEL) Features 0 GND is connected to COM1 and MIC is connected to COM2 1 GND is connected to COM2 and MIC is connected to COM1

The controller 36 in this example can directly select the processor of the terminal, and is configured to control the switch S1 through a GPIO (General Purpose Input Output) when the current working state of the FM earphone base circuit is a high-fidelity audio playing state. The enable end is in a closed state, so that the impedance of the headphone to ground is equal to the parallel impedance of the switch S1 and the bead BEAD1. This value is smaller than the impedance value of the switch S1 by 100 milliohms. For details, see FIG. The experimental data related to HIFI when the FM earphone block circuit is closed in the high-fidelity audio playing state after the switch S1 is closed is compared with the experimental data in FIG. 2, and the switch S1 can be clearly seen. After closing, the impedance of the headphone to ground in this example has little effect on crosstalk and THD+N in the high-fidelity audio playback state, which is negligible. The controller 36 is also set to operate in the FM headphone circuit. In the working state, the enable end of the switch S1 through the GPIO is turned off, so that the impedance of the headphone to ground is equal to the impedance of the bead BEAD1, thus, the FM property Will not be affected.

In FIG. 4, the FM signal processing circuit is connected to the earphone ground circuit A1, that is, the FM signal in FIG. 4 is introduced from the earphone ground circuit A1. In an exemplary embodiment, the FM signal in this example is also It can be introduced from the right channel interface circuit A2 or the left channel interface circuit A3. For details, as shown in FIG. 7, the FM signal in FIG. 7 is introduced from the left channel interface circuit A3 through the DC blocking capacitor C10.

8 is a schematic diagram of an FM earphone base circuit in another example of the embodiment. The FM frequency modulation circuit in this example is an LC parallel resonant circuit, wherein L5 is 100 nH, C3 is 33 pf, and LC parallel resonant frequency is about 100 MHz. The ground DC impedance is 500 milliohms (the value of the inductance and capacitance in the LC parallel resonant circuit can be changed, as long as the FM performance is guaranteed), and the impedance matching circuit in this example can also be the switch chip WAS4732, that is, the switch S1.

In an exemplary embodiment, the current working state of the FM earphone base circuit in this embodiment further includes a normal audio playing state, and the controller 36 can control the switch S1 to be disconnected when the current working state is the normal audio playing state, or The controller 36 can also control the switch S1 to close when the current working state is the normal audio playing state.

On the basis of the foregoing content of the first embodiment and the embodiment, the present embodiment further provides an audio terminal. As shown in FIG. 9, the audio terminal 90 provided in this embodiment includes any of the above-mentioned FM earphones. Circuit 30.

The FM earphone base circuit and the audio terminal provided in this embodiment are controlled to be connected to or disconnected from the FM frequency modulation circuit by the controller, so that the impedance between the earphone ground wire and the motherboard ground wire can be controlled by the controller. Therefore, the terminal can be compatible with HIFI and FM, which improves the satisfaction of the user experience.

Embodiment 3:

On the basis of the foregoing embodiment, the present embodiment provides a method for controlling an audio terminal. The audio terminal in this embodiment may be any audio terminal in the second embodiment. Referring to FIG. 10, the audio terminal is shown in FIG. The control method includes step S1001 and step S1002.

Step S1001: Acquire a current working state of the FM earphone base circuit of the audio terminal.

In an exemplary embodiment, the current operating states of the FM headset base circuit include, but are not limited to, a high fidelity audio playback state, an FM operating state, and a normal audio playback operating state.

Step S1002: The impedance matching circuit is controlled to be turned on or off according to the current working state of the FM earphone base circuit.

In an exemplary embodiment, if the current working state of the FM earphone base circuit is a high-fidelity audio playing state, the impedance matching circuit can be controlled to be connected to the FM frequency modulation circuit, and the impedance matching circuit is connected in parallel with the FM frequency modulation circuit, so The ground impedance of the FM earphone base circuit is smaller than the impedance value of any one of the impedance matching circuit and the FM frequency modulation circuit, so that the impedance of the FM earphone base circuit to ground can be satisfied in the high fidelity audio playing state; if the FM earphone The current working state of the seat circuit is the FM working state, then the impedance matching circuit can be controlled to be disconnected from the FM frequency modulation circuit. At this time, the ground impedance value of the FM earphone base circuit is the impedance value of the FM frequency modulation circuit, thereby satisfying the FM working state. The requirements for the ground impedance of the FM earphone base circuit; if the current working state of the FM earphone base circuit is the normal audio playback working state, the impedance matching circuit can be controlled to be disconnected from the FM frequency modulation circuit, or the impedance matching circuit and the FM can also be controlled. The FM circuit is turned on, which can be flexibly set by the developer according to the actual application scenario.

The control method of the audio terminal provided by this embodiment obtains the current working state of the FM earphone base circuit of the audio terminal, and controls the impedance matching circuit to be connected to or disconnected from the FM frequency modulation circuit according to the current working state of the FM earphone socket circuit. Therefore, the terminal can be compatible with HIFI and FM, which improves the satisfaction of the user experience.

Embodiments of the present invention provide a computer readable storage medium storing computer executable instructions, which are implemented by a processor to implement the above control method of an audio terminal.

Those of ordinary skill in the art will appreciate that all or some of the steps, systems, and functional blocks/units of the methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be composed of several physical The components work together. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer readable medium, which may include computer storage media (or non-transitory media) and communication media (or transitory media). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and nonvolatile, implemented in any method or technology for storing information, such as computer readable instructions, data structures, program modules or other data. Sex, removable and non-removable media. Computer storage media include, but are not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), and Electrically Erasable Programmable Read-only Memory (EEPROM). Flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical disc storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or Any other medium used to store the desired information and that can be accessed by the computer. Moreover, it is well known to those skilled in the art that communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism, and can include any information delivery media. .

A person skilled in the art can understand that the technical solutions of the present application can be modified or equivalent, without departing from the spirit and scope of the technical solutions of the present application, and should be included in the scope of the claims of the present application.

Industrial applicability

The embodiment of the invention provides an FM earphone base circuit, an audio terminal and a control method thereof. The controller obtains the current working state of the FM earphone base circuit of the audio terminal, and controls the impedance matching circuit and the FM according to the current working state of the FM earphone base circuit. The FM circuit is turned on or off, thereby controlling the impedance between the ground wire of the earphone base and the ground wire of the main board, so that the terminal can be compatible with HIFI and FM, thereby improving the satisfaction of the user experience.

Claims (11)

An FM earphone base circuit comprising: a headphone interface circuit, an audio codec, an FM frequency modulation circuit, an FM signal processing circuit, an impedance matching circuit and a controller; The earphone interface circuit is connected to the audio codec, and the audio codec transmits the processed audio signal to the external earphone connected to the earphone interface circuit through the earphone interface circuit for playing; The FM signal processing circuit is respectively connected to the earphone interface circuit and the audio codec, and is configured to introduce an FM signal through the earphone interface circuit and send it to the earphone interface circuit when the earphone interface circuit is connected to the external earphone Audio codec; The FM frequency modulation circuit is connected to the earphone interface circuit, and the impedance matching circuit is connected in parallel with the FM frequency modulation circuit; The controller is connected to the control end of the impedance matching circuit, and is configured to control the impedance matching circuit to be turned on or off with the FM frequency modulation circuit according to a current working state of the FM earphone base circuit, the FM The impedance value of the parallel circuit obtained after the frequency modulation circuit is connected in parallel with the impedance matching circuit is less than or equal to the high fidelity impedance threshold. The FM earphone base circuit of claim 1 , wherein the earphone interface circuit comprises an earphone ground circuit, and a left channel interface circuit and a right channel interface circuit respectively connected to the audio codec; The FM frequency modulation circuit is connected to the earphone ground circuit. The FM earphone base circuit of claim 2, wherein said FM signal processing circuit is coupled to at least one of said earphone ground circuit, said left channel interface circuit, and a right channel interface circuit for said headphone interface The FM signal is introduced when the circuit is connected to an external earphone. The FM earphone mount circuit of any of claims 1-3, wherein the impedance matching circuit has an impedance value equal to the high fidelity impedance threshold. The FM earphone base circuit according to any one of claims 1 to 3, wherein the operating state comprises a high fidelity audio playing state and an FM working state; The controller is configured to control the impedance matching circuit to be connected to the FM frequency modulation circuit when the current working state is a high fidelity audio playing state, and to control when the current working state is an FM working state. The impedance matching circuit is disconnected from the FM frequency modulation circuit. The FM earphone base circuit according to claim 5, wherein said working state further comprises a normal audio playing state; The controller is further configured to control the impedance matching circuit to be disconnected from the FM frequency modulation circuit when the current operating state is a normal audio playback state. An audio terminal comprising the FM earphone base circuit of any of claims 1-6. A method of controlling an audio terminal is applied to the audio terminal according to claim 7, the method comprising: Obtaining a current working state of the FM earphone base circuit of the audio terminal; And controlling the impedance matching circuit to be turned on or off from the FM frequency modulation circuit according to a current working state of the FM earphone base circuit. The control method of the audio terminal according to claim 8, wherein the working state comprises a high fidelity audio playing state and an FM working state; Controlling the impedance matching circuit to be turned on or off from the FM frequency modulation circuit according to the current working state of the FM earphone base circuit includes: Controlling the impedance matching circuit to be connected to the FM frequency modulation circuit when the current working state is a high fidelity audio playing state; When the current working state is an FM working state, the impedance matching circuit is controlled to be disconnected from the FM frequency modulation circuit. The control method of the audio terminal according to claim 9, wherein the working state further comprises a normal audio playing state; Controlling the impedance matching circuit to be turned on or off from the FM frequency modulation circuit according to a current working state of the FM earphone base circuit includes: And controlling the impedance matching circuit to be disconnected from the FM frequency modulation circuit when the current working state is a normal audio playing state. A computer readable storage medium storing computer executable instructions that, when executed by a processor, implement the control method of the audio terminal of claim 8.

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