CN100525407C

CN100525407C - TV set with FM receiver function

Info

Publication number: CN100525407C
Application number: CNB2005100719275A
Authority: CN
Inventors: 刘强; 刘超; 徐延校; 陈湛; 王少敏; 张广峰
Original assignee: Haier Group Corp; Qingdao Haier Electronics Co Ltd
Current assignee: Haier Group Corp; Qingdao Haier Electronics Co Ltd; Qingdao Haier Multimedia Co Ltd
Priority date: 2005-05-26
Filing date: 2005-05-26
Publication date: 2009-08-05
Anticipated expiration: 2025-05-26
Also published as: CN1870730A

Abstract

This invention discloses a TV set with the function of FM receivers including a 12C bus controlling the searching, a SAW filter, an amplifier, an automatic gain control circuit, a mixing circuit, a L10.7 filter, a sound power amplifying circuit and a FM discriminator, in which, the FM broadcast signals are demodulated to 37.3MHz controlled by said 12C bus, said mixing circuit is used to load the sound signals to 10.7MHz controlled by the automatic gain control circuit and signals of other frequencies are filtered by the L10.7 MHz filter and the sound signals are demodulated by the FM discriminator and sent into the sound power amplifying circuit to be played.

Description

Television set with FM receiver function

Technical field

The present invention relates to a kind of television set, relate in particular to a kind of television set with radio function.

Background technology

Along with the development of technology, popular more and more higher to the requirement of TV functions, desirable TV is can receive television signals and can accept fm broadcast signal.

The typical fm trap filter that television set adopted is a tuning circuit, and its wave amplitude is single deep notch shape to the characteristic curve of frequency, roughly occupy the center of frequency modulation frequency range, and its width is enough to the FM signal of whole frequency modulation section is decayed.When tuning TV signal, if remove the performance that fm trap filter will reduce receiver, this receiver is mainly the subsidiary FM receiver of a television set.If increase by an electronic switch formula fm trap filter, can increase the design cost of this receiver and cause circuit structure complicated more, and cause degenerating of itself performance because of introducing stray capacitance and stray inductance.US Patent specification US6876401B2 discloses a kind of television set that can receive FM broadcasting, comprises the first trap portion and the second trap portion, and a control voltage acts on the first switching diode negative electrode, so that change the frequency of first trap; Another control voltage acts on the second switch diode cathode, so that change the frequency of second trap; When TV signal, the video if signal of adjacent lower layer channel and audio signal are weakened; When FM broadcasting arrived, video if signal and synchronization subcarrier signal were weakened.

Utility model patent specification ZL02251875.4 discloses a kind of TV additional FM radio device, utilizes the original tuning and control system of television set, and Chirp is accepted circuit, thereby realizes the wireless function of full-automatic frequency modulation.Its structure comprises an arrowband input circuit, be used to receive the IF signal of the electronic tuning unit output after pre-intermediate level circuit amplifies, and at 38MHz resonance, FM first intermediate-freuqncy signal of selecting 38MHz is as output; One fm radio circuit is used for the output signal that receives the arrowband input circuit is carried out the first intermediate frequency amplification, mixing, the amplification of second intermediate frequency and demodulation, obtains stereo composite signal; One crossings on different level decoding circuit is used for the stereo composite signal that obtains is decoded, and obtains R, L audio signal.The crossings on different level decoding circuit is made of integrated circuit TDA7040.Fm radio circuit is made of integrated circuit TDA7088T.This technology increases on cost a lot, the input circuit of FM radio receiver signal and decoding circuit all are to finish in the inside of TDA7088T, the voice signal that is decoded voice signal and television set switches with TC4053, utilizes the sound amplifying circuit of television set itself that the FM radio receiver signal is played back then.

Summary of the invention

At prior art problems, the object of the present invention is to provide a kind of circuit structure simple, the low good television set of audio frequency effect that receives of cost with FM receiver function.

For achieving the above object, the present invention by the following technical solutions: a kind of television set with FM receiver function of the present invention comprises that control searches the I of platform ²C bus, electronic tuning unit U101, Surface Acoustic Wave Filter (SAW), amplifier, automatic gain control circuit, mixting circuit, L10.7 filter, sound power amplifying circuit, it is characterized in that, also comprise a FM frequency discriminator, fm broadcast signal is by described I ²The control of C bus, separate by described electronic tuning unit U101 and to be transferred to 37.3MHZ, under the control of described automatic gain control circuit, utilize described mixer voice signal to be loaded on the carrier frequency of 10.7MHZ, through the target signal filter of described L10.7 filter with other frequencies, by described FM frequency discriminator with the voice signal demodulation after, send into described sound power amplifying circuit sound playing come out.

Have in the television set of FM receiver function in the present invention, comprise a N201 integrated circuit, its inside is equipped with described mixting circuit and FM frequency discriminator.

Have in the television set of FM receiver function in the present invention, described Surface Acoustic Wave Filter adopts chip Z101, it is connected with described electronic tuning unit U101, SDA, the AGC end of this electronic tuning unit U101 is connected with described integrated circuit N201, and two IFIN ends of described integrated circuit N201 are connected with two SO ends of described Z101.

Have in the television set of FM receiver function in the present invention, described L10.7 filter adopts chip XZ203, and chip XZ203 is in parallel with described integrated circuit N201.

Have in the television set of FM receiver function in the present invention, described sound power amplifying circuit adopts chip N601, and the input of chip N601 is connected with described integrated circuit N201, and output is connected with loud speaker.

The present invention is placed on television set superchip N201 inside with the decoded portion of FM signal, after using electronic tuning unit that the FM signal is received, all processing comprise that mixing-circuit such as AGC-frequency discrimination all are integrated in super monolithic N201 inside, have simplified circuit structure, provided cost savings.

Description of drawings

Fig. 1 has the circuit block diagram of the television set of FM receiver function for the present invention.

Fig. 2 has the physical circuit figure of the television set of FM receiver function for the present invention.

Embodiment

With reference to accompanying drawing 1, be a kind of circuit block diagram of the present invention with television set of FM receiver function, comprise and control the I that searches platform ²The C bus, the SAW filter, amplifier, automatic gain control circuit, mixting circuit, the L10.7 filter, the sound power amplifying circuit, one FM frequency discriminator, when television set is operated in FM broadcast receiver state, its range of receiving is at FM frequency range (87-108MHZ), the FM radiofrequency signal is imported from electronic tuning unit U101 radio-frequency terminals, electronic tuning unit U101 not only can the demodulation cable TV signal, and can separate the FM signal and be transferred to 37.3MHZ, under the control of described automatic gain control circuit, utilize described mixer voice signal to be loaded on the carrier frequency of 10.7MHZ, the filter of the described L10.7MHZ of process is with the target signal filter of other frequencies, by described FM frequency discriminator with the voice signal demodulation after, send into described sound power amplifying circuit sound playing come out.

With reference to accompanying drawing 2, integrated circuit N201 inside is equipped with described mixting circuit and FM frequency discriminator.U101 is an electronic tuning unit, and itself also needs television set, but the electronic tuning unit of television set can only the demodulation cable TV signal, and the element that the present invention uses can demodulation FM voice signal; Common electronic tuning unit demodulates the signals to 38MHZ, and we are put into 37.3MHZ to the FM signal; The back is through the inside mixing of N201, with the sound carrier frequency signal that obtains 10.7MHZ after 48MHZ signal and the 37.3MHZ mixing.The SAW filter adopts chip Z101, and it is connected with electronic tuning unit U101, and the SDA of electronic tuning unit U101, AGC end is connected with described integrated circuit N201, and two IF IN ends are connected with described Z101.

XZ203 is the filter of 10.7M sound carrier frequency signal, and other television set the insides do not have this filter;

Voice signal outputs among the N601 (sound amplification circuit) at 38 pin of N201, through outputing to loud speaker after amplifying sound playing is come out.This circuit also exists in TV set circuit, but in our patent, after the switching by the N201 IC interior, the FM signal of demodulation is input among the N601, thereby realizes that the FM signal plays back.

Claims

1, a kind of television set with FM receiver function comprises and controls the I that searches platform ²C bus, electronic tuning unit U101, Surface Acoustic Wave Filter, amplifier, automatic gain control circuit, mixting circuit, L10.7 filter, sound power amplifying circuit is characterized in that, also comprise a FM frequency discriminator, and fm broadcast signal is by described I ²The control of C bus, separate by described electronic tuning unit U101 and to be transferred to 37.3MHZ, under the control of described automatic gain control circuit, utilize described mixer voice signal to be loaded on the carrier frequency of 10.7MHZ, through the target signal filter of described L10.7 filter with other frequencies, by described FM frequency discriminator with the voice signal demodulation after, send into described sound power amplifying circuit sound playing come out.

2, a kind of television set with FM receiver function according to claim 1 is characterized in that, comprises integrated circuit, and its inside is equipped with described mixting circuit and FM frequency discriminator.

3, a kind of television set according to claim 1 with FM receiver function, it is characterized in that, described Surface Acoustic Wave Filter adopts chip Z101, it is connected with described electronic tuning unit U101, SDA, the AGC end of this electronic tuning unit U101 is connected with described integrated circuit N201, and two IF IN ends of described integrated circuit N201 are connected with two SO ends of described Z101.

4, a kind of television set with FM receiver function according to claim 1 is characterized in that, described L10.7 filter adopts chip XZ203, and chip XZ203 is in parallel with described integrated circuit N201.

5, a kind of television set with FM receiver function according to claim 1 is characterized in that, described sound power amplifying circuit adopts chip N601, and the input of chip N601 is connected with described integrated circuit N201, and output is connected with loud speaker.