CN2579087Y - Super small radio electronic toner - Google Patents

Abstract

The utility model relates to a superminiature radio electronic high frequency head, which comprises an FM receiving channel, an AM receiving channel and a shell, wherein, an FM secondary frequency selection loop is arranged in the FM channel, three intermediate frequency filters are connected between the FM secondary frequency selection loop and an FM frequency mixing loop thereof, and an FM oscillating signal which is amplified by an FM oscillating output loop is connected with a phase locked loop circuit; AM secondary local oscillation, AM secondary mixing and AM secondary intermediate frequency amplification are arranged in an AM channel, an AM primary intermediate frequency signal and a secondary local oscillation signal generate a secondary intermediate frequency signal through the AM secondary mixing, and an AM primary local oscillation signal which is amplified by an AM primary local oscillation output loop is connected with the phase locked loop circuit. The utility model adopts optimization designs of a radio, the phase locked loop, etc. The utility model has the advantages of small volume and coverage of all channels. Compared with existing products, the receiving sensitivity, the interference immunity and the selectivity of the utility model are obviously enhanced. The utility model has already obtained the 'CE' and 'FCC' certifications, and is used for a wide range of DVD and MP3 products.

Description

Microminiature radio reception electronic tuning tuner

Technical field

The utility model relates to the electronic tuning tuner of wireless receiver, specifically is a kind of Subminiature electronic tuned high frequency head that radio reception receives that is used for.

Background technology

Lack reasons such as space, complex circuit designs owing to existence, in the past automobile DVD﹠amp; MP3 does not have function of radio receiver, causes defectives such as function singleness and cost performance be on the low side.Along with automobile DVD﹠amp; MP3 further popularizes, and the user has proposed requirements at the higher level to its performance, as the microminiature DVD﹠amp of band function of radio receiver; MP3 etc., but the existing general volume of radio reception tuner is bigger, can not with microminiature DVD﹠amp; MP3 is supporting.

Summary of the invention

The purpose of this utility model is to overcome the above-mentioned deficiency of prior art, and a kind of microminiature radio reception electronic tuning tuner is provided, to satisfy the microminiature high-performance DVD﹠amp with function of radio receiver; The supporting demand of MP3.

The microminiature radio reception electronic tuning tuner that the utility model proposes, comprise FM receive path, AM receive path and screening can, it is characterized in that: in the FM receive path, be provided with FM secondary frequency-selective circuit, FM secondary frequency-selective circuit is connected to its FM high-frequency amplifier circuit output, connect three intermediate-frequency filters (CF1, CF3, CF4) between described FM secondary frequency-selective circuit and its FM mixing return circuit, the FM oscillator signal that is amplified output by FM vibration output loop connects a phase-locked loop circuit.In the AM receive path, be provided with AM secondary local oscillator loop, AM secondary mixing loop and AM secondary intermediate frequency amplifier circuit, the secondary local oscillation signal output in the intermediate-freuqncy signal output of an intermediate frequency amplifier circuit of its AM and AM secondary local oscillator loop connects AM secondary mixing loop respectively, second intermediate-freuqncy signal output in AM secondary mixing loop connects AM secondary intermediate frequency amplifier circuit, the output of AM secondary intermediate frequency amplifier circuit connects the AM detecting circuit, by AM once this vibration output loop local oscillation signal of AM of amplifying output connect described phase-locked loop circuit.

This microminiature tuner is to be the Combinatorial Optimization design at center with high-performance radio reception integrated circuit and phase-locked loop circuit, frequency range covers all-channel, need not add phase-locked loop circuit and stereo decoding circuit in addition during entire machine design, only need to inject just direct output audio signal of a high-frequency signal, Application Design is simplified greatly, and then shortened the design cycle.Its FM passage adopts the mode of three filter filterings to adopt the mode of two filter filterings to have better signal-selectivity than traditional tuner; Adopt twice intermediate frequency (IF) Design to effectively raise AM selectivity, antijamming capability and practical sensitivity.Be provided with stereo noise control circuit, can obtain good impedance matching and control by a larger margin, quite desirable through the stereo audibility of test.

The belt ground wire of large tracts of land is set respectively around local oscillation circuit and the high frequency input circuit on the pcb board, the portion product of frequency modulation local oscillation circuit except that middle week all adopt surface mount elements simultaneously, the pin of all product all is close to wiring board, and the oscillator signal that makes can't utilize these elements to extraneous radiation.

It adopts the direct insertion structure of microminiature, and volume is little, and receiving sensitivity, interference free performance and selectivity etc. obviously improve than existing product.This tuner is obtained Europe " CE " authentication and the U.S. " FCC " authentication simultaneously, can be supporting with DVD and MP3, and design has the microminiature DVD and the MP3 product of function of radio receiver.

Description of drawings

Fig. 1 is the utility model electronic tuning tuner functional-block diagram;

Fig. 2 is its exemplary embodiments circuit diagram;

Fig. 3 is three intermediate-frequency filter connection diagrams of Fig. 2;

Fig. 4 is the stereo noise control circuit figure of Fig. 2;

Fig. 5 is to be the annular of the large tracts of land around high frequency input circuit ground connection schematic diagram on the pcb board;

Fig. 6 is the large tracts of land annular earth connection schematic diagram of oscillating circuit part on the pcb board;

Fig. 7 a-d is its exemplary embodiments structural representation;

Fig. 8 adopts the automobile audio of this tuner to use the periphery circuit reference diagram with first-selection.

Embodiment

Further describe below in conjunction with the embodiment accompanying drawing.As shown in Figure 1, 2, this microminiature radio reception electronic tuning tuner comprises FM receive path, AM receive path, phase-locked loop circuit and screening can.

Wherein, the FM receive path contains: FM input frequency-selective circuit, FM high-frequency amplifier circuit, FM local oscillator loop, FM vibration output loop, FM mixing return circuit, FM intermediate frequency amplifier circuit, FM frequency-discriminating circuit, FM stereo decoding circuit, audio amplifier circuit and FM secondary frequency-selective circuit; FM secondary frequency-selective circuit is connected to FM high-frequency amplifier circuit output, is provided with three intermediate-frequency filters (CF1, CF3, CF4) between described FM secondary frequency-selective circuit and FM mixing return circuit.One output of FM local oscillator loop connects FM vibration output loop, and the FM oscillator signal that is amplified output by FM vibration output loop connects phase-locked loop circuit.

The AM receive path contains: AM high-frequency amplifier circuit, AM frequency-selective circuit, local oscillator loop of AM, AM once vibrate output loop, mixing return circuit of AM, intermediate frequency amplifier circuit of AM, AM detecting circuit, low pass filter, audio amplifier circuit, AM secondary local oscillator loop, AM secondary mixing loop and AM secondary intermediate frequency amplifier circuit.The secondary local oscillation signal output in the intermediate-freuqncy signal output of an intermediate frequency amplifier circuit of its AM and AM secondary local oscillator loop connects AM secondary mixing loop respectively, second intermediate-freuqncy signal output in AM secondary mixing loop connects AM secondary intermediate frequency amplifier circuit, and the output of AM secondary intermediate frequency amplifier circuit connects the AM detecting circuit.Local oscillator loop of AM one output connects the AM output loop that once vibrates, by AM once this vibration output loop amplify local oscillation signal of AM of exporting and connect described phase-locked loop circuit.

Signal is divided into two-way after antenna enters: the one tunnel is the FM signal, and another road is the AM signal.

The FM signal at first enters FM input frequency-selective circuit, and all interference signals beyond the selected frequency are excluded, and is used to improve the selectivity and the antijamming capability of tuner.Signal enters the FM high-frequency amplifier circuit through capacitively coupled, and signal is amplified; This circuit selects for use the low noise FM pipe with AGC effect as amplifier tube, effectively raises machine-noise ratio and has controlled the distortion of trunk offering power.Signal is amplified into FM secondary frequency-selective circuit, and its effect is the same with the frequency-selective circuit of front; Signal cooperates three intermediate-frequency filter filtering of back again after the secondary frequency-selecting, make tuner can reach international CE Valuation Standard.

At the same time, FM local oscillator loop produces an oscillator signal, is divided into two-way after this oscillator signal produces: the one tunnel enters FM vibration output loop amplification back is sent to phase-locked loop circuit; Another road signal is sent to the FM mixting circuit, and the FM aerial signal will carry out mixing with the FM local oscillation signal in the FM mixting circuit, thereby produces the 10.8MHz intermediate-freuqncy signal.Carrying out intermediate frequency in this intermediate-freuqncy signal input FM intermediate frequency amplifier circuit amplifies, to enter the FM frequency-discriminating circuit after intermediate-freuqncy signal is amplified and carry out frequency discrimination, the low frequency signal that frequency discrimination goes out enters FM stereo decoding circuit after high-pass filtering, the audio amplifier circuit that the stereo audio signal that decodes will enter AM and FM function amplifies, audio frequency after the amplification is connected with complete machine by 11 and 12 pin, finishes the overall process that changes from the FM aerial signal to audio signal.The mixing of FM, the amplification of FM intermediate frequency, FM frequency discrimination and stereo decoding all are to finish in radio reception IC inside, have only a spot of peripheral circuit, thereby can keep the stability of overall process work.

The AM signal enters the AM high-frequency amplifier circuit through inductance coupling high, and signal is amplified; This circuit is selected for use has AGC effect low noise FET pipe as amplifier tube, effectively raises machine-noise ratio and has controlled the distortion of trunk offering power.Signal is amplified into the AM frequency-selective circuit, and signal is carried out bandpass filtering.At the same time, local oscillator loop of AM produces an oscillator signal, is divided into two-way after this oscillator signal produces: the one tunnel enters the AM output loop that once vibrates amplifies the back and is sent to Phase Lock Loop IC; Another road signal is sent to the AM mixting circuit.Same local oscillator signal of aerial signal will carry out mixing in mixting circuit of AM, thereby produce the 10.81MHz intermediate-freuqncy signal.This intermediate-freuqncy signal is sent into and is carried out the intermediate frequency amplification in intermediate frequency amplifier circuit of AM, to enter AM secondary mixing circuit after signal amplifies and carry out secondary mixing with AM secondary local oscillation signal, by the AM secondary local oscillator loop that a fundamental frequency is formed with radio reception IC internal circuit, the AM secondary local oscillation signal supply AM secondary mixing circuit that produces a 10.26MHz is used to finish the AM secondary mixing.To produce the AM secondary intermediate-freuqncy signal of a 450KHz after the mixing, this signal will enter AM secondary intermediate frequency amplifier circuit and carry out the intermediate frequency amplification.And then AM secondary intermediate-freuqncy signal after the amplification enters the AM detecting circuit and carries out detection, the audio signal that detection goes out will enter AM after low-pass filtering and the shared audio amplifier circuit of FM amplifies, audio frequency after the amplification is connected with complete machine by 11 and 12 pin, thereby finishes the overall process that changes from the AM aerial signal to audio signal.The AM signal comprises the signal of MW wave band and LW wave band.Its twice intermediate frequency (IF) Design effectively raises AM selectivity, antijamming capability and real sensitivity, by a traditional intermediate frequency (IF) Design incomparable.

For reducing volume, improve stability and reliability, satisfy supporting needs such as small size DVD and MP3 machine, above-mentioned electronic tuning tuner has adopted radio reception integrated circuit (IC) 1 and Phase Lock Loop IC 2, exemplary embodiments radio reception IC is the LA1787M chip, and Phase Lock Loop IC is a LC72144M chip etc.Above-mentioned FM mixing, the amplification of FM intermediate frequency, FM frequency discrimination and FM stereo decoding, and a mixing of AM, an intermediate frequency amplification of AM and AM secondary local oscillator all realize by radio reception integrated circuit LA1787M internal circuit.All the other peripheral circuit parts have been carried out certain improvement on the traditional circuit basis, all 80% of peripheral cell adopt high performance surface mount elements, and the wires design of circuit board has also been carried out optimal design.

This tuner frequency modulation local oscillation circuit no longer adopts original spring coil, and what replace is small-sized middle week; The triode that circuit is used and other peripheral cell also no longer adopt original plug-in unit element, and what replace is whole-colored surface mount elements.Original circuit design makes tuner when being given a shock, cause the moving or the variation of shape of element occurrence positions of tuner frequency modulation main shock circuit, thereby cause the variation of distributed inductance and distributed capacitance, cause the change of frequency of oscillation, finally cause noise to influence audibility.This kind of integral high frequency head can make tuner when running car after the above technological improvement of talking about, and no longer causes the variation of position of components or shape because of vibrations, thereby has effectively controlled the generation of noise, has improved the anti-seismic performance of tuner.The middle microminiaturization that adds radome and surface mount elements week has effectively suppressed oscillator signal and has carried out radiated interference to external world by element, has reduced the radiation of tuner.

As seen this kind of integral high frequency head integrated level is very high, and it is simple and convenient that complete machine is established.It carries phase-locked loop circuit and stereo decoding circuit, only needs to inject just direct output audio signal of a high-frequency signal.Compare with traditional tuner, need not add phase loop circuit with lock and stereo decoding circuit during entire machine design, make design obtain simplifying, and then shortened the design cycle, for having won valuable time in new product conversion market.

In order to obtain " CE " authentication simultaneously, select for use and a large amount of improvement work have been done in aspect such as line design at portion's product.Three-3dB of employing waveband width is that the 10.8Hz filter of 180 ± 40KHz or plurality of specifications such as 180 ± 25KHz or 180 ± 20KHz carries out the frequency modulation intermediate frequency filtering, and wherein CF1 links to each other with T1, and its method of attachment indicates shown in 2 as Fig. 3; CF3 links to each other with CF4, and its method of attachment indicates shown in 1 as Fig. 3.With traditional tuner adopt two-3dB waveband width be 150 ± 40KHz (or ± 25KHz or ± 20KHz) 10.7MHz filter carries out the frequency modulation intermediate frequency filtering, adding BPF of aerial signal input increase compares, it adopts the mode of three filter filterings to adopt the mode of two filter filterings to have better signal-selectivity than traditional tuner, makes this kind of tuner be waltzed through " CE " authentication.Particularly on filter is selected for use, changing traditional tuner employing-3dB waveband width is the rule of 150 ± 40KHz filter, and adopt-the 3dB waveband width is wideer, and (180 ± 40KHz) filter is used for improving producing bad phenomenon such as distortion, malsegregation owing to waveband width is too narrow in the past.Owing to adopted three filters, must not increase a BPF at the aerial signal input as in the past simultaneously; Owing to increase a BPF, useful signal also had been attenuated a part in the decay interference signal, so reduced every electric property of tuner in the past, and particularly practical sensitivity generally can descend about 6dB.

This tuner is also having breakthrough aspect the stereo noise control (SNC), Fig. 4 is its stereo noise control circuit, this circuit contains triode TR1, series diode D6 and adjustable resistance R8 between the SNC end (28 pin) of triode TR1 emitter-base bandgap grading and radio reception integrated circuit LA1787M, transistor base and collector electrode shunt capacitance C8, the base stage of triode receives 27 pin of sound integrated circuit LA1787M, and the collector electrode of triode meets Vcc.After triode TR1 amplified, by diode D6 and a resistance R 8,28 pin from radio reception IC entered radio reception IC again, and stereo noise is controlled from the stereo noise control signal of 27 pin of radio reception IC output.Changed general tuner only with the traditional approach of a resistance control, this circuit has increased a triode and has amplified, and can obtain good impedance match and control by a larger margin; Particularly added a diode between triode and semifixed resistor, this kind design not only makes impedance matching better, also can make stereo noise control curve more become perfect.After above improvement design, no matter you are in the fine spacious Plain of broadcast singal, and still in the high building very poor bustling Dou He city of broadcast singal of standing in great numbers, but uppick broadcast programs true to nature all has the stereo audibility of shock.

In order to obtain " FCC " authentication, select for use and a large amount of improvement work have been done in aspect such as wiring board wiring at portion's product.At first the frequency modulation local oscillation circuit has adopted small-sized middle week, compares with the spring coil that is adopted in the past, and the screening can that it carries can utilize this element to extraneous radiation by very effective prevention oscillator signal.The portion product of frequency modulation local oscillation circuit except that middle week all adopt surface mount elements simultaneously, and the pin of all product all is close to wiring board, and the oscillator signal that makes can't utilize these elements to extraneous radiation.

With reference to Fig. 5, this tuner adopts large tracts of land annular ground connection to handle around the frequency-modulated antenna input circuit.Prevented that effectively the external interference signal from disturbing this circuit, both input circuit had been protected effectively, various interference capability such as the anti-intermediate frequency that is used to improve tuner disturbs, the interference of false picture.Thereby guarantee that this kind of integral high frequency head false appearance suppresses to reach more than the 60dB, intermediate frequency suppresses to reach more than the 70dB, 1/2 intermediate frequency suppresses to reach the above high standard of 75dB.

As shown in Figure 6, oscillating circuit partly is provided with large-area annular earth connection on the tuner pcb board, utilizes other element or circuit to extraneous radiation to avoid oscillator signal.Tuner 8 pin are connected on the ground wire of motherboard, and link to each other with the large tracts of land annular ground connection of tuner the inside (shown in wiring board positive and negative overlay chart), the tuner ground wire is tightly connected together with the motherboard ground wire, make the interference signal that is radiated on the tuner ground wire obtain being distributed on the motherboard ground wire.

The large tracts of land annular ground connection that tuner 8 pin link to each other is enclosed in the inside (week during the local oscillation circuit as shown in the wiring board front elevation is little, the local oscillation circuit variable capacitance diode as shown in wiring board reverse side figure) with the components and parts of local oscillation circuit.Utilize this large-area annular ground connection, can effectively oscillator signal be controlled in this annular ring, make oscillator signal can't utilize other element or circuit to extraneous radiation.Improvement design by above has reduced tuner radiation to external world widely, is able to pass through smoothly " FCC " authentication.

A kind of microminiature tuner structure of the present utility model is shown in Fig. 7 a-d, and the small size design that it adopts 50*43.7*10mm is about 1/3 (traditional integral high frequency head is generally 85*45*18mm) of traditional integral high frequency head volume.Only need take the inner space of general automobile audio about 1.5%, can solve the problem that main frame lacks the design space fully.Arrange its pin position and each pin function also can clearly be found out from figure.Wherein, the corresponding relation of pin position is: 1-AM ANT, 2-FM ANT, 3-GND, 4-VCC (7.7-8.7V), 5-VT, 6-FM VCC, 7-N.C (FM IF OUT), 8-GND, 9-SD, 10-VSM, 11-L CH OUT, 12-R CH OUT, 13-DET OUT, 14-VCC (8-9V), 15-GND, 16-D0,17-CLK, 18-DI, 19-CE, 20-VDD (4.5-5.5V).

The double-side fibre plate that adopts 1.2t is as substrate, screening can adopts the high strength tinplate compression moulding of 0.4t, pin terminals adopts the high strength tinplate compression moulding of 0.5t, the pin of the single face papery substrate of more traditional tuner 1.2t, the common tinplate compression moulding of screening can, 0.4t of the common tinplate compression moulding of 0.3t is compared, and its mechanical strength has had very big raising.The employing of the high-intensity material of this kind effectively raises mechanical performances such as the anti-vibration of this kind of integral high frequency head, anti-twist, high temperature resistance.

Fig. 8 uses the periphery circuit reference diagram for the automobile audio that adopts this tuner with first-selection.Its simple periphery circuit has alleviated engineer's design burden greatly, has shortened the design cycle, seizes market in advance for product and has won valuable time.

Claims (6)

1, a kind of microminiature radio reception electronic tuning tuner comprises FM receive path, AM receive path and screening can, it is characterized in that:

In the FM receive path, be provided with FM secondary frequency-selective circuit, FM secondary frequency-selective circuit is connected to its FM high-frequency amplifier circuit output, connect three intermediate-frequency filters between described FM secondary frequency-selective circuit and its FM mixing return circuit, the FM oscillator signal that is amplified output by FM vibration output loop connects a phase-locked loop circuit;

In the AM receive path, be provided with AM secondary local oscillator loop, AM secondary mixing loop and AM secondary intermediate frequency amplifier circuit, the secondary local oscillation signal output in the intermediate-freuqncy signal output of an intermediate frequency amplifier circuit of its AM and AM secondary local oscillator loop connects AM secondary mixing loop respectively, second intermediate-freuqncy signal output in AM secondary mixing loop connects AM secondary intermediate frequency amplifier circuit, the output of AM secondary intermediate frequency amplifier circuit connects the AM detecting circuit, by AM once this vibration output loop local oscillation signal of AM of amplifying output connect described phase-locked loop circuit.

2, microminiature radio reception electronic tuning tuner according to claim 1, it is characterized in that: adopt radio reception integrated circuit LA1787, wherein FM mixing, the amplification of FM intermediate frequency, FM frequency discrimination and FM stereo decoding, and a mixing of AM, an intermediate frequency amplification of AM and AM secondary local oscillator all realize by radio reception integrated circuit LA1787 internal circuit.

3, as microminiature radio reception electronic tuning tuner as described in the claim 2, it is characterized in that being provided with a stereo noise control circuit, this circuit contains triode TR1, series diode D6 and adjustable resistance R8 between the SNC of triode TR1 emitter-base bandgap grading and radio reception integrated circuit LA1787M end, transistor base and collector electrode shunt capacitance C8, the base stage of triode receives 27 pin of sound integrated circuit LA1787M, and the collector electrode of triode connects power Vcc.

4, microminiature radio reception electronic tuning tuner according to claim 1 is characterized in that: described three 10.8MHz filters that intermediate-frequency filter employing-3dB waveband width is 180 ± 40KHz or 180 ± 25KHz or 180 ± 20KHz.

5, as microminiature radio reception electronic tuning tuner as described in claim 1 or 2 or 4, it is characterized in that: oscillating circuit partly is provided with large-area annular earth connection on the pcb board, has adopted large tracts of land annular ground connection on the pcb board around the high frequency input circuit.

6, microminiature radio reception electronic tuning tuner according to claim 1 is characterized in that: pcb board adopts the double-side fibre base board of 1.2t, and screening can is the high strength tinplate shell of 0.4t.

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