TW201935844A - Electronic device with function of receiving FM radio - Google Patents

Abstract

An electronic device with a function of receiving frequency modulation (FM) radio includes an earphone jack, a signal ground terminal, an inductor, an FM processing circuit, an audio output circuit, and a compensation circuit. The earphone jack has a left-channel output terminal, a right-channel output terminal, and an earphone ground terminal. The inductor has two terminals respectively connected to the earphone ground terminal and the signal ground terminal. The FM processing circuit is connected to the earphone ground terminal. The compensation circuit includes a first adder and a second adder. The first adder includes a first input terminal for connecting to the audio output circuit to receive a left-channel audio, a first output terminal for connecting to the left-channel output terminal, and a first feedback input terminal for connecting to the earphone ground terminal. The second adder includes a second input terminal for connecting to the audio output circuit to receive a right-channel audio, a second output terminal for connecting to the right-channel output terminal, and a second feedback input terminal for connecting to the earphone ground terminal.

Description

Electronic device with function of listening to FM radio station

The invention relates to an electronic device with a function of listening to a Frequency Modulation (FM) radio station, and more particularly to an electronic device that can use a ground wire of a headset as an FM antenna to listen to an FM radio station.

Existing electronic devices, such as mobile devices such as smart phones, have the function of listening to FM radio stations, and the cable length of the headset is exactly the length required by the FM antenna, so the ground wire of the headset can be used as an FM antenna to receive FM radio signal. Because the ground wire of the earphone is used as an FM antenna, if you want to retrieve the signal of the FM radio station, you must connect an inductor in series with the ground wire that interconnects the electronic device and the earphone to prevent the FM signal from being short-circuited directly to the ground. And this inductor will generate a small voltage V _S , which will cause the left and right channel audio that can be received by the headset to be disturbed, and reduce the crosstalk and signal-to-noise ratio (SNR) anti-noise. The ability to further affect the sound quality of the headset.

FIG. 1 is a circuit block diagram of a conventional electronic device 1 with a function of listening to an FM radio station. Referring to FIG. 1, the electronic device 1 includes a headphone socket 11, a signal ground terminal 12, an inductor 13, a frequency modulation processing circuit 14 and an audio output circuit 15. The headphone socket 11 has a left channel output terminal 111, a right channel output terminal 112, and a headphone ground terminal 113. The signal ground terminal 12 is used to provide a zero potential reference point inside the electronic device 1. The inductor 13 has a first terminal 131 and a second terminal 132. The first terminal 131 is connected to the earphone ground terminal 113 and the second terminal 132 is connected to the signal ground terminal 12. The FM processing circuit 14 is connected to the grounding terminal 113 of the earphone, and is used for extracting the signal of the FM radio station. The audio output circuit 15 is used to provide left channel audio (voltage V _L ) and right channel audio (voltage V _R ).

The headphone 3 includes a left-channel headphone 31, a right-channel headphone 32, and a headphone plug (not shown). The left-channel headphone 31 is connected to the headphone plug through the left-channel signal cable 331 at one end, and connected to the headphone plug through the ground wire 333 at the other end One end of the right channel earphone 32 is connected to the headphone plug through the right channel signal line 332, and the other end is connected to the headphone plug through the ground line 333. When the earphone plug of the earphone 3 is inserted into the earphone socket 11 of the electronic device 1, one end of the left-channel earphone 31 is connected to the left-channel output terminal 111 through the left-channel signal line 331, and the other end is connected to the earphone ground terminal 113 through the ground wire 333, and One end of the right channel earphone 32 is connected to the right channel output terminal 112 through a right channel signal line 332, and the other end is connected to the earphone ground terminal 113 through a ground line 333. At this time, the ground wire 333 of the earphone 3 is used as an FM antenna, and the received FM signal (frequency ω) will generate a slight voltage V _S on the inductor (impedance ωL), that is, the voltage V exists at the ground terminal 113 of the earphone. _S , causing the left channel audio voltage received by the left channel headset 31 to change from V _L to (V _L -V _S ), and the right channel audio voltage received by the right channel headset 32 changed from V _R to interference It is (V _R -V _S ), and the anti-noise ability of reducing cross distortion and signal-to-noise ratio further affects the sound quality of the headphones.

The purpose of the present invention is to provide an electronic device with the function of listening to an FM radio station, so that when the ground wire of the earphone is used as an FM antenna, the interference of left and right channel audio received by the earphone is improved, and the cross distortion and The anti-noise capability of the noise to noise ratio further improves the sound quality of the headphones.

In order to achieve the above or other objectives, the present invention provides an electronic device with a function of listening to an FM radio station. The electronic device includes a headphone socket, a signal ground terminal, an inductor, a frequency modulation processing circuit, an audio output circuit, and a compensation circuit. The earphone socket has a left channel output terminal, a right channel output terminal and a headphone ground terminal. The signal ground terminal is used to provide a zero potential reference point inside the electronic device. The inductor has a first terminal and a second terminal, the first terminal is connected to the earphone ground terminal, and the second terminal is connected to the signal ground terminal. The FM processing circuit is connected to the ground terminal of the earphone, and is used to retrieve the signal of the FM radio station. The audio output circuit is used to provide left channel audio and right channel audio. The compensation circuit includes a first adder and a second adder. The first adder includes a first input terminal, a first output terminal, and a first feedback input terminal. The first input terminal is connected to an audio output circuit to receive left channel audio, the first output terminal is connected to a left channel output terminal, and the first The feedback input terminal is connected to the earphone ground terminal. The second adder includes a second input terminal, a second output terminal, and a second feedback input terminal. The second input terminal is connected to the audio output circuit to receive the right channel audio, the second output terminal is connected to the right channel output terminal, and the second The feedback input terminal is connected to the earphone ground terminal.

In an embodiment of the invention, the electronic device is a mobile device.

In an embodiment of the invention, the mobile device is a smart phone.

By setting a compensation circuit in the electronic device, when the ground wire of the earphone is used as an FM antenna, the left and right channel audio voltages provided by the left and right channel outputs of the earphone socket of the electronic device can be increased to (V _L + V _S ) and (V _R + V _S ), in order to compensate the voltage V _S existing in the earphone ground terminal of the earphone socket caused by the voltage V _S generated on the inductor, so that the left and right channel audio voltages received by the earphone are respectively It is improved to V _L and V _R , and the anti-noise capability of cross-distortion and signal-to-noise ratio is enhanced to further improve the sound quality of the headphones.

In order to make the description of this disclosure more detailed and complete, the following presents an illustrative description of the implementation modes and specific embodiments of the present invention, but this is not a limited form of implementing or applying the specific embodiments of the present invention. In addition, some conventional elements that are not related to the technical features of the present invention are omitted, and the same or similar symbols in the embodiments represent the same or similar elements. As used herein, when an element is referred to as being "connected" or "coupled" to another element, it can be that the element is directly connected or coupled to the other element; or that there is a Or more additional elements, that is, one element is connected to another element via one or more additional elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no additional elements there.

FIG. 2 is a circuit block diagram of an electronic device 2 with a function of listening to an FM radio station according to an embodiment of the present invention. Referring to FIG. 2, the electronic device 2 is, for example, a mobile device such as a smart phone, but is not limited thereto. For example, the electronic device 2 may be an electronic device such as a tablet computer. The electronic device 2 includes a headphone socket 21, a signal ground terminal 22, an inductor 23, a frequency modulation processing circuit 24, an audio output circuit 25, and a compensation circuit 26. The earphone socket 21 has a left channel output terminal 211, a right channel output terminal 212, and a headphone ground terminal 213, but is not limited thereto, and may also have a microphone input terminal, for example. The signal ground terminal 22 is used to provide a zero-potential reference point inside the electronic device 2. The inductor 23 has a first terminal 231 and a second terminal 232. The first terminal 231 is connected to the earphone ground terminal 213, and the second terminal 232 is connected to the signal ground terminal 22. The FM processing circuit 24 is connected to the grounding terminal 213 of the earphone, and is used for extracting the signal of the FM radio station. The audio output circuit 25 is used to provide left channel audio (voltage V _L ) and right channel audio (voltage V _R ).

The headphone 3 includes a left-channel headphone 31, a right-channel headphone 32, and a headphone plug (not shown). The left-channel headphone 31 is connected to the headphone plug through the left-channel signal cable 331 at one end, and connected to the headphone plug through the ground cable 333 at the other end. One end of the right channel earphone 32 is connected to the headphone plug through the right channel signal line 332, and the other end is connected to the headphone plug through the ground line 333. When the earphone plug of the earphone 3 is inserted into the earphone socket 21 of the electronic device 2, one end of the left-channel earphone 31 is connected to the left-channel output terminal 211 through the left-channel signal line 331, and the other end is connected to the earphone ground terminal 213 through the ground wire 333, and One end of the right channel earphone 32 is connected to the right channel output terminal 212 through a right channel signal line 332, and the other end is connected to the earphone ground terminal 213 through a ground line 333.

The compensation circuit 26 includes a first adder 27 and a second adder 28. The first adder 27 includes a first input terminal 271, a first output terminal 272, and a first feedback input terminal 273. The first input terminal 271 is connected to the audio output circuit 25 to receive left-channel audio, and the first output terminal 272 is connected to the left. The channel output terminal 211 and the first feedback input terminal 273 are connected to the earphone ground terminal 213. The second adder 28 includes a second input terminal 281, a second output terminal 282, and a second feedback input terminal 283. The second input terminal 281 is connected to the audio output circuit 25 to receive right channel audio, and the second output terminal 282 is connected to the right The channel output terminal 212 and the second feedback input terminal 283 are connected to the earphone ground terminal 213.

By providing a compensation circuit 26 in the electronic device 2, when the ground wire 333 of the earphone 3 is used as an FM antenna, the compensation circuit 26 changes the left and right channel audio voltages provided by the audio output circuit 25 from V _L and V _R Raise to (V _L + V _S ) and (V _R + V _S ) respectively, so as to compensate the voltage V _S existing in the earphone ground terminal 213 of the earphone socket 21 due to the voltage V _S generated on the inductor 23, so that the earphones The left and right channel audio voltages received by 3 (or left-channel headphones 31 and right-channel headphones 32) are improved to V _L and V _R , respectively, and the anti-noise capability of cross-distortion and signal-to-noise ratio is enhanced, further improving the sound quality of the headphones. .

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and retouching without departing from the spirit and scope of the present invention. The scope of protection shall be determined by the scope of the attached patent application.

1, 2‧‧‧ electronic devices

11, 21‧‧‧ headphone socket

111, 211‧‧‧ Left channel output

112, 212‧‧‧ right channel output

113, 213‧‧‧earphone ground

12, 22‧‧‧ signal ground

13, 23‧‧‧ Inductors

131, 231‧‧‧ first end

132, 232‧‧‧ second end

14, 24‧‧‧ FM processing circuit

15, 25‧‧‧ audio output circuit

26‧‧‧Compensation circuit

27‧‧‧The first adder

271‧‧‧first input

272‧‧‧first output

273‧‧‧First feedback input

28‧‧‧Second Adder

281‧‧‧second input

282‧‧‧Second output

283‧‧‧Second feedback input terminal

3‧‧‧ headphones

31‧‧‧Left Channel Headphones

32‧‧‧ Right Channel Headphone

331‧‧‧Left channel signal cable

332‧‧‧Right channel signal cable

333‧‧‧ ground wire

V _S ‧‧‧Voltage

V _L ‧‧‧ Left channel audio voltage provided by audio output circuit

V _R ‧‧‧ audio channel audio voltage provided by audio output circuit

FIG. 1 is a circuit block diagram of a conventional electronic device with a function of listening to an FM radio station; and FIG. 2 is a circuit block diagram of an electronic device with a function of listening to an FM radio station according to an embodiment of the present invention.

Claims (3)

An electronic device with the function of listening to an FM radio station includes: a headphone socket having a left channel output terminal, a right channel output terminal and a headphone ground terminal; a signal ground terminal for providing a zero potential inside the electronic device Reference point; an inductor having a first end and a second end, the first end is connected to the earphone ground terminal, the second end is connected to the signal ground terminal; an FM processing circuit is connected to the earphone ground terminal, and Extracting signals from an FM radio station; an audio output circuit for providing a left channel audio and a right channel audio; and a compensation circuit including: a first adder including a first input terminal, a first An output terminal and a first feedback input terminal, the first input terminal is connected to the audio output circuit to receive the left channel audio, the first output terminal is connected to the left channel output terminal, and the first feedback input terminal Connected to the earphone ground terminal; and a second adder, which includes a second input terminal, a second output terminal, and a second feedback input terminal, the second input terminal is connected to the audio output circuit to receive the audio output circuit; Channel audio, the second output terminal connected to the right channel output terminal, the second feedback input terminal connected to the ground terminal of the earphone. The electronic device with the function of listening to an FM radio station according to item 1 of the scope of patent application, wherein the electronic device is a mobile device. The electronic device with the function of listening to an FM radio station according to item 2 of the scope of patent application, wherein the mobile device is a smart phone.