CN201515434U - Set-top box and tuner circuit thereof - Google Patents
Set-top box and tuner circuit thereof Download PDFInfo
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- CN201515434U CN201515434U CN2009202054689U CN200920205468U CN201515434U CN 201515434 U CN201515434 U CN 201515434U CN 2009202054689 U CN2009202054689 U CN 2009202054689U CN 200920205468 U CN200920205468 U CN 200920205468U CN 201515434 U CN201515434 U CN 201515434U
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Abstract
The utility model discloses a set-top box and a tuner circuit thereof. The tuner circuit comprises a radio-frequency signal input end, a radio-frequency signal output end and a passive loop module. The radio-frequency signal input end is used for receiving signals of an external cable television, and the passive loop module is connected between the radio-frequency signal input end and the radio-frequency signal output end and is used for non-conduction when the set-top box is powered up and for conduction when the set-top box is powered down, so as to output the analog television signals of the radio-frequency signal input end to the radio-frequency signal output end. Since the passive loop module is additionally arranged in the tuner, the radio-frequency signal output end can still output signals even when the set-top box is not powered up. Moreover, since the attenuation of the output signals is low, the user can watch analog television programs without plugging additional signal wires under the condition that the set-top box is not powered up.
Description
Technical field
The utility model relates to a kind of TV set-top box, relates in particular to a kind of improvement of set-top box circuit.
Background technology
Along with the develop rapidly and the popularization of digital television techniques, apparatus of digital television receiving also increases day by day, because people's growth in the living standard, and more and more stronger to HD digital TV demand, the application of digital TV set-top box also more and more widely.
The top box of digital machine product was not with passive loops to lead to function in the past, loop radiofrequency signal output did not just have signal to export after set-top box closed power down, if want to watch analog television program, the user will manually extract holding wire and be inserted into the TV RF signals input from set-top box, switching digital TV and simulated television need often to plug holding wire back and forth, have caused very big inconvenience to the user like this.
Therefore, prior art is still waiting to improve and improve.
The utility model content
The purpose of this utility model is that the above-mentioned shortcoming at prior art provides a kind of set-top box and tuner circuit thereof, and under the situation that its set-top box does not power up, the radiofrequency signal output also has signal output, and attenuated output signal is very little.
Technical solutions of the utility model are:
A kind of tuner circuit of set-top box, comprise the radio-frequency (RF) signal input end that is used for external cable TV signal, and radiofrequency signal output, wherein, also comprise the passive ring module that is connected between described radio-frequency (RF) signal input end and the radiofrequency signal output, described passive ring module is used for not conducting when set-top box powers up, and conducting when set-top box is cut off the power supply outputs to the radiofrequency signal output with the anolog TV signals of described radio-frequency (RF) signal input end.
Described tuner circuit, wherein, it also comprises: low noise amplifier, frequency divider and electronic switch;
Described low noise amplifier input links to each other with described radio-frequency (RF) signal input end, is used for that the radiofrequency signal of input is carried out low noise and amplifies;
Described frequency divider links to each other with described low noise amplifier output, is used to export the identical loop signals of two-way, and first via loop signals inserts the rear end tuned cell, and the second tunnel loop signals inserts electronic switch;
Described electronic switch output connects described radiofrequency signal output, is used for selecting modulation signal or described the second tunnel loop signals to the radiofrequency signal output according to switch controlling signal control.
Described tuner circuit, wherein, also comprise a modulator block, described modulator block is connected with described electronic switch and external input signal and control port module respectively, be used for the AV baseband signal is modulated to radio frequency, and described modulation signal is outputed to described electronic switch;
Described external input signal and control port module link to each other with described electronic switch, are used to described electronic switch that switch controlling signal is provided.
Described tuner circuit, wherein, it also comprises the middle amplification module that links to each other with described rear end tuned cell, is used for the signal of described rear end tuned cell output is carried out power amplification, the output differential intermediate frequency is to offer the rear end decoding.
The described tuner circuit of one claim, wherein, described electronic switch comprises: loop signals module, modulation signal module, switch control module and signal output module; Wherein,
Described switch control module is used for selecting described loop signals module or modulation signal module are connected to described signal output module according to described switch controlling signal;
Described loop signals module is used to receive described the second tunnel loop signals, and described the second tunnel loop signals is sent to described signal output module;
Described modulation signal module is used to receive described modulation signal, and described modulation signal is sent to described signal output module;
Described signal output module is used for exporting described the second tunnel loop signals or described modulation signal to described radiofrequency signal output.
Described tuner circuit, wherein, described switch control module comprises first switch triode (V7) and second switch triode (V6), the base stage of described first switch triode (V7) links to each other with the switch controlling signal end (MS) of external input signal and control port module by first resistance (R110), and its emitter connects power supply; The base stage of described second switch triode (V6) links to each other with the collector electrode of described first switch triode (V7) by second resistance (R88), its grounded emitter, with and collector electrode connect power supply by the 3rd pull-up resistor (R87);
Described loop signals module comprises first switching diode (D17), the positive pole of described first switching diode (D17) links to each other with described the second tunnel loop signals, also links to each other with the collector electrode of described first switch triode (V7) by the 4th resistance (R82) by an electric capacity (C113), the negative pole of described first switching diode (D17) links to each other with the positive pole of second switch diode (D20), and the negative pole of described second switch diode (D20) links to each other with described radiofrequency signal output by first filter capacitor (C121);
Described modulation signal module comprises the 3rd switching diode (D16), the positive pole of described the 3rd switching diode (D16) links to each other with described modulation signal by electric capacity (C104), its anodal resistance (R81) that passes through links to each other with the collector electrode of described second switch triode (V6), and the negative pole of described the 3rd switching diode (D16) links to each other with the negative pole of described first switching diode (D17);
Described signal output module comprises first filter capacitor (C121), one end of described first filter capacitor (C121) connects the negative pole of described first switching diode (D17) and the negative pole of described the 3rd switching diode (D16) by second switch diode (D20), the other end described radiofrequency signal output that links to each other; When described switch controlling signal is controlled described first switch triode (V7) conducting, first switching diode (D17) conducting, described signal output module is exported described loop signals to described radiofrequency signal output; When described switch controlling signal control first switch triode (V7) by the time, second switch triode (V6) ends, the 3rd switching diode (D16) conducting, described signal output module is exported described modulation signal to described radiofrequency signal output.
Described tuner circuit, wherein, described passive ring module comprises that a model is the switch transition element of BF1108, input the 4th pin of described switch transition element links to each other with described radio-frequency (RF) signal input end by electric capacity (C120), output the 3rd pin of described switch transition element links to each other with described radiofrequency signal output by electric capacity (C121), the 1st pin of described switch transition element connects with reference to ground, the 2nd pin of described switch transition element connects power supply by the resistance (R2) and the resistance (R104) of series connection from the set-top box circuit, output the 3rd pin of described switch transition element also connects power supply by the resistance (R37) and the resistance (R104) of series connection, radiofrequency signal with described radio-frequency (RF) signal input end when described switch transition element is used for the set-top box outage outputs to the radiofrequency signal output, not conducting when described switch transition element powers up.
Described tuner circuit, wherein, described modulator block comprises that a model is the integrated chip of TA1372FNG, the 11st of described integrated chip, 13 pin link to each other with the power supply of tuner circuit, 12 pin link to each other with the loop filtering circuit, output the 15th pin of described integrated chip links to each other with described electronic switch, the 2nd pin of described integrated chip links to each other with the video input signals of external input signal and control port module, the 5th pin of described integrated chip links to each other with the audio input signal of external input signal and control port module, the 6th pin of described integrated chip links to each other with the switch controlling signal end (MS) of external input signal and control port module by a resistance R 79, and the 8th pin of described integrated chip links to each other with the output channel control end (CS) of external input signal and control port module.
A kind of set-top box, comprise tuner circuit, described tuner circuit comprises the radio-frequency (RF) signal input end that is used for external cable TV signal, and radiofrequency signal output, wherein, also comprise the passive ring module that is connected between described radio-frequency (RF) signal input end and the radiofrequency signal output, described passive ring module is used for not conducting when set-top box powers up, conducting when set-top box is cut off the power supply outputs to the radiofrequency signal output with the anolog TV signals of described radio-frequency (RF) signal input end.
Described set-top box is characterized in that, described tuner circuit also comprises:
With the low noise amplifier that described radio-frequency (RF) signal input end links to each other, be used for that the radiofrequency signal of input is carried out low noise and amplify, and the input of the radiofrequency signal after will amplifying frequency divider;
With the frequency divider that described low noise amplifier links to each other, be used to export the identical loop signals of two-way, and the second tunnel loop signals is inserted electronic switch;
With the modulator block that external input signal and control port module link to each other, be used for the AV baseband signal is modulated to radio frequency, and described modulation signal is outputed to described electronic switch;
The electronic switch that links to each other with described frequency divider and modulator block respectively is used for according to a switch controlling signal control and selects modulation signal or described the second tunnel loop signals to the radiofrequency signal output.
A kind of set-top box provided by the utility model and tuner circuit thereof, owing in tuner, increased the passive ring module, under the situation that its set-top box does not power up, the radiofrequency signal output also has signal output, and attenuated output signal is very little, makes the user also not need other plug holding wire just can watch analog television program when set-top box does not power up; And by in the tuner of TV set-top box, increasing electronic switching circuit, when powering up, set-top box selects to export loop signals or modulation signal as required, make the user can select to see digital television program easily or see analog television program, enriched the function of digital TV set-top box, in addition, built-in modulator block in tuner also makes higher while of tuner circuit integrated level of the utility model set-top box also simplify the design of client's complete machine.
Description of drawings
Fig. 1 is the tuner circuit schematic diagram of the set-top box of the utility model embodiment 1;
Fig. 2 is the tuner circuit block diagram of the set-top box of the utility model embodiment 2;
Fig. 3 is the modulator block and the electronic switch partial circuit diagram of the set-top box tuner circuit of the utility model embodiment 2;
Fig. 4 is the electronic switching circuit block diagram of the set-top box tuner circuit of the utility model embodiment 2.
Embodiment
The utility model provides a kind of set-top box and tuner circuit thereof, and is clearer, clear and definite for making purpose of the present invention, technical scheme and advantage, below with reference to the accompanying drawing embodiment that develops simultaneously the present invention is described in further details.
TV set-top box among the utility model embodiment 1, it comprises tuner circuit 100, as shown in Figure 1, described tuner circuit 100, comprise the radio-frequency (RF) signal input end 101 that is used for external cable TV signal, and be used for the radiofrequency signal output 102 that links to each other with the television signal input, the improvements of the utility model embodiment 1 are on prior art top box basis, between its radio-frequency (RF) signal input end 101 and radiofrequency signal output 102 and connect a passive ring module 110, the conducting when set-top box is cut off the power supply of described passive ring module 110, can directly output to the anolog TV signals of described radio-frequency (RF) signal input end 101 the radiofrequency signal output and give television set, described passive ring module 110 not conductings when set-top box powers up this moment.
Among the embodiment 1, described passive ring module 110 bags one model is the switch transition elements T 2 of BF1108, as shown in Figure 1, input the 4th pin of described switch transition elements T 2 links to each other 101 by capacitor C 120 with described radio-frequency (RF) signal input end, output the 3rd pin of described switch transition element links to each other with described radiofrequency signal output 102 by capacitor C 121, the 1st pin of described switch transition element connects with reference to ground, the 2nd pin of described switch transition element connects the 5V power supply by the resistance R 2 and the resistance R 104 of series connection from the set-top box circuit, output the 3rd pin of described switch transition element also connects the 5V power supply by the resistance R 37 and the resistance R 104 of series connection.
Among the embodiment 1, TV signal is connected to radio-frequency (RF) signal input end 101, when set-top box energising start, be that tuner circuit 100 adds the 5V power supply, T2 switch transition element BF1108 the 3rd pin also has 5V voltage, not conducting of switch transition element BF1108 this moment, then TV signal to rear end tuned cell is handled, and gives television set from radiofrequency signal output 102 output digital TV in high resolution programs after the modulation treatment.When set-top box is closed power down, tuner does not have 5V voltage, when T2 switch transition element BF1108 the 3rd pin does not have 5V voltage, the automatic conducting of T2 switch transition element BF1108 internal circuit this moment, anolog TV signals are imported from capacitor C 120 to T2 switch transition element BF1108 the 4th pin input, export radiofrequency signal output 102 to from the 3rd pin, so reach the logical effect of passive loops, like this, when set-top box is cut off the power supply, set-top box does not have the output of digital TV in high resolution program, but can export anolog TV signals, need not manually to plug back and forth holding wire just can continue to teleview, greatly facilitate the user, and attenuated output signal is very little, full frequency band 57-801MHZ and original input signal mutually specific damping in-3dbuv.
TV set-top box among the utility model embodiment 2, be on the basis of embodiment 1, in its tuner circuit 100, increase modulator block 160 and be used for anolog TV signals and the electronic switch 130 of digital television signal conversion, as shown in Figure 2, described tuner circuit 100 comprises passive ring module 110, and it also comprises:
With the low noise amplifier 120 that described radio-frequency (RF) signal input end 101 links to each other, be used for that the radiofrequency signal of input is carried out low noise and amplify, and the input of the radiofrequency signal after will amplifying frequency divider 140;
With the frequency divider 140 that described low noise amplifier 120 links to each other, be used to export the identical loop signals of two-way, and the second tunnel loop signals is inserted electronic switch 130;
With the rear end tuned cell 150 that described frequency divider 140 links to each other, be used to receive the first via loop signals of described frequency divider 140 outputs, and the output intermediate-freuqncy signal;
The modulator block 160 that links to each other with external input signal and control port module 210 is used for the AV baseband signal is modulated to radio frequency, and described modulation signal is outputed to described electronic switch 130;
The electronic switch 130 that links to each other with described frequency divider 140 and modulator block 160 respectively is used to control the modulation signal of selecting described modulator block 160 outputs of output or described the second tunnel loop signals to radiofrequency signal output 102.
Among the embodiment 2, radiofrequency signal inserts described low noise amplifier 120 from radio-frequency (RF) signal input end 101, and the radiofrequency signal of 120 pairs of inputs of low noise amplifier is carried out low noise and amplified, the radiofrequency signal input frequency divider 140 after will amplifying then.Frequency divider 140 is divided into radiofrequency signal the identical two-way loop signals of mutual isolation: the first via loop signals and the second tunnel loop signals.Rear end tuned cell 150 comprises High Amplifier Circuit, double-tuned circuit, mixing and amplifying circuit etc.The first via loop signals that frequency divider produces is linked into the High Amplifier Circuit in the rear end tuned cell 150, so that control automatically according to the power of signal by High Amplifier Circuit, entering into double-tuned circuit, double-tuned circuit then mainly is that out-of-band interference signal is carried out effective filtering, enter into main IC at last and carry out mixing and amplification, export a 44MHZ intermediate-freuqncy signal at last and offer mainboard rear end decoding circuit.The second tunnel loop signals of frequency divider 140 outputs is linked into electronic switch 130, the also continuous modulator block 160 of electronic switch 130, modulator block 160 that the tuner circuit of the TV set-top box in the present embodiment is built-in, described modulator block 160 receives the input of AV baseband signal, the AV baseband signal is modulated to radio frequency gets on, modulation signal is linked into electronic switch 130.Electronic switch 130 is used for selecting the output modulation signal or the second tunnel loop signals, and the signal the selected signal output port by electronic switch 130 is linked into radiofrequency signal output 102.Wherein radiofrequency signal is that frequency is the broadband ATSC digital signal of 57-801MHZ.
Among the embodiment 2, described tuner circuit 100 further comprises: the middle amplification module 170 that links to each other with described rear end tuned cell 150, be used for the signal of described rear end tuned cell 150 outputs is carried out power amplification, output digital differential signal DIF1, DIF2 are to offer rear end decoding IC.
Among the utility model embodiment 2, the physical circuit figure of described modulator block 160 and electronic switch 130 as shown in Figure 3, described modulator block 160 comprises that a model is the integrated chip IC2 of TA1372FNG, the 11st of described integrated chip IC2,13 pin link to each other with the power supply of tuner circuit, 12 pin link to each other with the loop filtering circuit, output the 15th pin of described integrated chip IC2 links to each other with described electronic switch, the 2nd pin of described integrated chip IC2 links to each other with the video input signals Video In of external input signal and control port module, the 5th pin of described integrated chip IC2 links to each other with the audio input signal Audio In of external input signal and control port module, the 6th pin of described integrated chip links to each other with the switch controlling signal end MS of external input signal and control port module, the 8th pin of described integrated chip links to each other with the CH3/CH4 output channel control end CS end of external input signal and control port module, the 5V power supply offers the 11st of integrated chip IC2 when set-top-box opening, 13 pin, the 4MHZ reference frequency offers integrated chip the 7th pin, chip this moment operate as normal.
The 8th pin of integrated chip IC2 connection CS end is CH3/CH4 output channel control end as mentioned above: as shown in Figure 3,
When the CS terminal is unsettled, IC2 the 15th pin RF-OUT output CH3 channel 61.25MHZ;
When CS terminal ground connection, IC2 the 15th pin RF-OUT output CH4 channel 67.25MHZ.
The 6th pin of described integrated chip IC2 connects switch controlling signal end MS, and switch controlling signal end MS is the control port of loop output or modulator CH3/CH4 output simultaneously, also is the radio-frequency carrier output control terminal:
When the MS terminal was unsettled, IC2 the 15th pin RF-OUT normally exported radio-frequency carrier signal.
When MS terminal ground connection, IC2 the 15th pin RF-OUT does not have radio-frequency carrier signal output IC2 chip not work.
Audio IN audio signal input 0.5VP-P.
VIdio IN vision signal input 1VP-P.
After delivering to radiofrequency signal output 102 by described electronic switch 130, the modulation signal of described modulator block 160 final modulation outputs is connected to the TV input terminal.Set-top box product modulator IC design in the past is in the TUNER outside, just the client controls oneself to design has on the mainboard, the set-top box of the utility model embodiment 2 makes the higher while of product integrated level of the present utility model also simplify the design of client's complete machine in TUNER inside modulator IC design in tuner.
Further, among the embodiment 2, described electronic switch 130 schematic diagrames specifically as shown in Figure 4, it is made up of loop signals module 132, modulation signal module 133, control module 131 and signal output module 134.The switch controlling signal that control module 131 is sent according to external input signal and control port module is selected described loop signals module 132 or modulation signal module 133 are connected to described signal output module 134.Loop signals module 132 receives the second tunnel loop signals, and the second tunnel loop signals is sent to signal output module 134.Modulation signal module 133 is used to receive described modulation signal, and described modulation signal is sent to described signal output module 134.Electronic switch 130 with the second tunnel loop signals or modulation signal output, exports selecteed signal to the radiofrequency signal output according to control signal control selection at last.
Electronic switch among the embodiment 2 can be circuit diagram as shown in Figure 3.Wherein, described switch control module comprises the first switch triode V7 and second switch triode V6, and the base stage of the described first switch triode V7 links to each other with switch controlling signal by first resistance R 110, and its emitter connects power supply; The base stage of described second switch triode V6 links to each other with the collector electrode of the described first switch triode V7 by second resistance R 88, its grounded emitter, with and collector electrode connect the 5V power supply by the 3rd pull-up resistor R87.
Described loop signals module comprises the first switching diode D17, the positive pole of the described first switching diode D17 links to each other with described the second tunnel loop signals, also links to each other with the collector electrode of the described first switch triode V7 by the 4th resistance R 82 by a capacitor C 113, the negative pole of the described first switching diode D17 links to each other with the positive pole of second switch diode D20, and the negative pole of described second switch diode D20 links to each other with described radiofrequency signal output by the first filter capacitor C121.
Described modulation signal module comprises the 3rd switching diode D16, the positive pole of described the 3rd switching diode D16 links to each other with described modulation signal by capacitor C 104, its anodal resistance R 81 of passing through links to each other with the collector electrode of described second switch triode V6, and the negative pole of described the 3rd switching diode D16 links to each other with the negative pole of the described first switching diode D17;
Described signal output module comprises the first filter capacitor C121, the end of the described first filter capacitor C121 connects the negative pole of the described first switching diode D17 and the negative pole of described the 3rd switching diode D16 by second switch diode D20, the other end described radiofrequency signal output that links to each other; When described switch controlling signal was controlled the described first switch triode V7 conducting, the first switching diode D17 positive pole obtained the conducting voltage greater than 0.7V, and described signal output module is exported described loop signals to described radiofrequency signal output; When described switch controlling signal control the first switch triode V7 by the time, second switch triode V6 ends, the 3rd switching diode D16 conducting, described signal output module is exported described modulation signal to described radiofrequency signal output.
In embodiment 2, by in the tuner of TV set-top box, increasing electronic switching circuit, the output of when active () radiofrequency signal output 102 can be selected loop output or modulator CH3/CH4 output by the user when set-top box powers up, concrete operation principle, as shown in Figures 2 and 3, the input of external cable TV signal through low noise amplifier 120 after by frequency divider 140 be divided into the two-way loop signals with, wherein the second tunnel loop signals is connected to the positive pole that C113 electric capacity enters into the first switching diode D17 of electronic switch, modulation signal outputs to C104 from the 15th pin of TA1372FNG integrated chip IC2 and enters into the 3rd switching diode D16 positive pole, by transistor V6, V7 is combined into a logic control, and synchronization selects one road signal to output to radiofrequency signal output 102.
When set-top box powered up, the user wanted to see analog television program, and it can select loop signals to output to radiofrequency signal output 102 by remote controller, the operation principle of this moment: as shown in Figure 3,
Described switch controlling signal end MS, this moment, the MS end needed ground connection, TA1372FNG integrated chip IC2 is not worked, because first resistance R, 110 ground connection, the B step voltage of the first switch triode V7 is lower than E step voltage 0.7V, so first switch triode V7 conducting, 5V voltage is from the E level input of the first switch triode V7, be added to again on the 4th resistance R 82 after passing through to the C level internally, the positive pole of the first switching diode D17 obtains 5V simultaneously, and conducting, this moment, second loop signals was smoothly by the first switching diode D17, exported to TV by the first filter capacitor C121 to radiofrequency signal output 102 again.
Simultaneously, voltage is 5V on second resistance R 88, thus second switch triode V6 conducting, after the conducting with the 5V of the 3rd pull-up resistor R87 (resistance 2.2K) dividing potential drop over the ground, so the 3rd switching diode D16 positive pole can not get 5V voltage thereby ends, so modulation signal is conducting to come.
When set-top box powered up, the user wanted to see digital television program, and it can select modulation signal to output to radiofrequency signal output 102 by remote controller, the operation principle of this moment: as shown in Figure 3:
That described switch controlling signal end MS needs is unsettled, make TA1372FNG integrated chip IC2 work, because first resistance R 110 is earth-free, the B step voltage of the first switch triode V7 equals C step voltage 5V, so first not conducting of switch triode V7,5V voltage can not be added on the 4th resistance R 82, do not end so there is 5V voltage on the positive pole of the first switching diode D17, so second loop signals is to pass through the first switching diode D17, radiofrequency signal output 102 loop free signals output this moment.
Meanwhile, owing to do not have 5V on second resistance R 88, so not conducting of second switch triode V6, the 5V of the 3rd pull-up resistor R87 dividing potential drop is added to the 3rd switching diode D16 positive pole and conducting, this moment, modulation signal passed through smoothly from the 3rd switching diode D16 positive pole, exported to TV by the first filter capacitor C121 to radiofrequency signal output 102 again.
In embodiment 2, signal output port by output impedance build-out resistor 106 ground connection, is mated thereby reach output impedance, improve stable output signal.
In embodiment 2, DC power supply by the 7th filter capacitor C109 ground connection, is carried out filtering to the DC power supply of 5V, can improve anti-ripple voltage and power supply interference capability, guaranteed the stability of circuit working.
A kind of set-top box provided by the utility model and tuner circuit thereof, owing in tuner, increased the passive ring module, under the situation that its set-top box does not power up, the radiofrequency signal output also has signal output, and attenuated output signal is very little, makes the user also not need other plug holding wire just can watch analog television program when set-top box does not power up; And by in the tuner of TV set-top box, increasing electronic switching circuit, when powering up, set-top box selects to export loop signals or modulation signal as required, make the user can select to see digital television program easily or see analog television program, enriched the function of digital TV set-top box, in addition, built-in modulator block in tuner also makes higher while of tuner circuit integrated level of the utility model set-top box also simplify the design of client's complete machine
Should be understood that, for those of ordinary skills, can be improved according to the above description or conversion, and all these improvement and conversion all should belong to the protection range of the utility model claims.
Claims (10)
1. the tuner circuit of a set-top box, comprise the radio-frequency (RF) signal input end that is used for external cable TV signal, and radiofrequency signal output, it is characterized in that, also comprise the passive ring module that is connected between described radio-frequency (RF) signal input end and the radiofrequency signal output, described passive ring module is used for not conducting when set-top box powers up, and conducting when set-top box is cut off the power supply outputs to the radiofrequency signal output with the anolog TV signals of described radio-frequency (RF) signal input end.
2. tuner circuit according to claim 1 is characterized in that it also comprises: low noise amplifier, frequency divider and electronic switch;
Described low noise amplifier input links to each other with described radio-frequency (RF) signal input end, is used for that the radiofrequency signal of input is carried out low noise and amplifies;
Described frequency divider links to each other with described low noise amplifier output, is used to export the identical loop signals of two-way, and first via loop signals inserts the rear end tuned cell, and the second tunnel loop signals inserts electronic switch;
Described electronic switch output connects described radiofrequency signal output, is used for selecting modulation signal or described the second tunnel loop signals to the radiofrequency signal output according to switch controlling signal control.
3. tuner circuit according to claim 2, it is characterized in that, also comprise a modulator block, described modulator block is connected with described electronic switch and external input signal and control port module respectively, be used for the AV baseband signal is modulated to radio frequency, and described modulation signal is outputed to described electronic switch;
Described external input signal and control port module link to each other with described electronic switch, are used to described electronic switch that switch controlling signal is provided.
4. tuner circuit according to claim 3, it is characterized in that it also comprises the middle amplification module that links to each other with described rear end tuned cell, be used for the signal of described rear end tuned cell output is carried out power amplification, the output differential intermediate frequency is to offer the rear end decoding.
5. according to the described tuner circuit of arbitrary claim in the claim 2 to 4, it is characterized in that described electronic switch comprises: loop signals module, modulation signal module, switch control module and signal output module; Wherein,
Described switch control module is used for selecting described loop signals module or modulation signal module are connected to described signal output module according to described switch controlling signal;
Described loop signals module is used to receive described the second tunnel loop signals, and described the second tunnel loop signals is sent to described signal output module;
Described modulation signal module is used to receive described modulation signal, and described modulation signal is sent to described signal output module;
Described signal output module is used for exporting described the second tunnel loop signals or described modulation signal to described radiofrequency signal output.
6. tuner circuit according to claim 5, it is characterized in that, described switch control module comprises first switch triode (V7) and second switch triode (V6), the base stage of described first switch triode (V7) links to each other with the switch controlling signal end (MS) of external input signal and control port module by first resistance (R110), and its emitter connects power supply; The base stage of described second switch triode (V6) links to each other with the collector electrode of described first switch triode (V7) by second resistance (R88), its grounded emitter, with and collector electrode connect power supply by the 3rd pull-up resistor (R87);
Described loop signals module comprises first switching diode (D17), the positive pole of described first switching diode (D17) links to each other with described the second tunnel loop signals, also links to each other with the collector electrode of described first switch triode (V7) by the 4th resistance (R82) by an electric capacity (C113), the negative pole of described first switching diode (D17) links to each other with the positive pole of second switch diode (D20), and the negative pole of described second switch diode (D20) links to each other with described radiofrequency signal output by first filter capacitor (C121);
Described modulation signal module comprises the 3rd switching diode (D16), the positive pole of described the 3rd switching diode (D16) links to each other with described modulation signal by electric capacity (C104), its anodal resistance (R81) that passes through links to each other with the collector electrode of described second switch triode (V6), and the negative pole of described the 3rd switching diode (D16) links to each other with the negative pole of described first switching diode (D17);
Described signal output module comprises first filter capacitor (C121), one end of described first filter capacitor (C121) connects the negative pole of described first switching diode (D17) and the negative pole of described the 3rd switching diode (D16) by second switch diode (D20), the other end described radiofrequency signal output that links to each other; When described switch controlling signal is controlled described first switch triode (V7) conducting, first switching diode (D17) conducting, described signal output module is exported described loop signals to described radiofrequency signal output; When described switch controlling signal control first switch triode (V7) by the time, second switch triode (V6) ends, the 3rd switching diode (D16) conducting, described signal output module is exported described modulation signal to described radiofrequency signal output.
7. tuner circuit according to claim 1, it is characterized in that, described passive ring module comprises that a model is the switch transition element of BF1108, input the 4th pin of described switch transition element links to each other with described radio-frequency (RF) signal input end by electric capacity (C120), output the 3rd pin of described switch transition element links to each other with described radiofrequency signal output by electric capacity (C121), the 1st pin of described switch transition element connects with reference to ground, the 2nd pin of described switch transition element connects power supply by the resistance (R2) and the resistance (R104) of series connection from the set-top box circuit, output the 3rd pin of described switch transition element also connects power supply by the resistance (R37) and the resistance (R104) of series connection, radiofrequency signal with described radio-frequency (RF) signal input end when described switch transition element is used for the set-top box outage outputs to the radiofrequency signal output, not conducting when described switch transition element powers up.
8. tuner circuit according to claim 2, it is characterized in that, described modulator block comprises that a model is the integrated chip of TA1372FNG, the 11st of described integrated chip, 13 pin link to each other with the power supply of tuner circuit, 12 pin link to each other with the loop filtering circuit, output the 15th pin of described integrated chip links to each other with described electronic switch, the 2nd pin of described integrated chip links to each other with the video input signals of external input signal and control port module, the 5th pin of described integrated chip links to each other with the audio input signal of external input signal and control port module, the 6th pin of described integrated chip links to each other with the switch controlling signal end (MS) of external input signal and control port module by a resistance R 79, and the 8th pin of described integrated chip links to each other with the output channel control end (CS) of external input signal and control port module.
9. set-top box, comprise tuner circuit, described tuner circuit comprises the radio-frequency (RF) signal input end that is used for external cable TV signal, and radiofrequency signal output, it is characterized in that also comprise the passive ring module that is connected between described radio-frequency (RF) signal input end and the radiofrequency signal output, described passive ring module is used for not conducting when set-top box powers up, conducting when set-top box is cut off the power supply outputs to the radiofrequency signal output with the anolog TV signals of described radio-frequency (RF) signal input end.
10. set-top box according to claim 9 is characterized in that, described tuner circuit also comprises:
With the low noise amplifier that described radio-frequency (RF) signal input end links to each other, be used for that the radiofrequency signal of input is carried out low noise and amplify, and the input of the radiofrequency signal after will amplifying frequency divider;
With the frequency divider that described low noise amplifier links to each other, be used to export the identical loop signals of two-way, and the second tunnel loop signals is inserted electronic switch;
With the modulator block that external input signal and control port module link to each other, be used for the AV baseband signal is modulated to radio frequency, and described modulation signal is outputed to described electronic switch;
The electronic switch that links to each other with described frequency divider and modulator block respectively is used for according to a switch controlling signal control and selects modulation signal or described the second tunnel loop signals to the radiofrequency signal output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202054689U CN201515434U (en) | 2009-09-25 | 2009-09-25 | Set-top box and tuner circuit thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009202054689U CN201515434U (en) | 2009-09-25 | 2009-09-25 | Set-top box and tuner circuit thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201515434U true CN201515434U (en) | 2010-06-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2009202054689U Expired - Lifetime CN201515434U (en) | 2009-09-25 | 2009-09-25 | Set-top box and tuner circuit thereof |
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| Country | Link |
|---|---|
| CN (1) | CN201515434U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108881757A (en) * | 2017-05-16 | 2018-11-23 | 扬智科技股份有限公司 | Tuner circuit, loop-through circuit and video broadcast system suitable for tuner |
-
2009
- 2009-09-25 CN CN2009202054689U patent/CN201515434U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108881757A (en) * | 2017-05-16 | 2018-11-23 | 扬智科技股份有限公司 | Tuner circuit, loop-through circuit and video broadcast system suitable for tuner |
| CN108881757B (en) * | 2017-05-16 | 2021-01-26 | 扬智科技股份有限公司 | Tuner circuit, loop-through circuit suitable for tuner, and video broadcasting system |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: Huizhou TCL King High Frequence El. Co.,Ltd. Assignor: TCL Group Co., Ltd. Contract record no.: 2011440020097 Denomination of utility model: Set-top box and tuner circuit thereof Granted publication date: 20100623 License type: Exclusive License Record date: 20110413 |
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| CX01 | Expiry of patent term |
Granted publication date: 20100623 |
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| CX01 | Expiry of patent term |