CN1231564A - Tuning assembly for television - Google Patents
Tuning assembly for television Download PDFInfo
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- CN1231564A CN1231564A CN 99100497 CN99100497A CN1231564A CN 1231564 A CN1231564 A CN 1231564A CN 99100497 CN99100497 CN 99100497 CN 99100497 A CN99100497 A CN 99100497A CN 1231564 A CN1231564 A CN 1231564A
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- capacitance diode
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- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
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- Superheterodyne Receivers (AREA)
- Circuits Of Receivers In General (AREA)
Abstract
The present invention provides a tuning assembly for televisione to asily obtain tracking with a local oscillation frequency. This tuner is equipped with tuning circuits 1 and 4 which have 1st varactor diodes 1b and 4b and select a receive signal by varying a tuning frequency through the capacity variation of the 1st varactor diodes 1b and 4b and a local oscillator 6 which has a 2nd varactor diode 6b and varies in local oscillation frequency through the capacity variation of the 2nd varactor diode 6b, and voltages applied across the 1st varactor diodes 1b and 4b are made smaller than the voltage applied across the 2nd varactor diode 6b.
Description
The present invention relates to tuning assembly for TV set, specifically, the present invention relates to make the suitable tuning assembly for TV set of tracking between the tuned frequency of the local oscillation frequency of local oscillator and resonant tank.
The loop that Fig. 7 uses for a kind of existing tv tuning component of expression constitutes schematic diagram.As shown in Figure 7, inputing to by input terminal 51 in the TV signal of antenna resonant tank 52, elder generation is by antenna resonant tank 52 selective reception channel TV signals and input to high-frequency amplifier 53.After high-frequency amplifier 53 amplifies, apply selectance characteristic jumpy with inter-stage resonant tank 54 again, and input to frequency mixer 55.The oscillation signals according that is provided by local oscillator 56 also inputs to frequency mixer 55, thereby the TV signal that will be positioned at receiving channels is transformed to intermediate-freuqncy signal, exports lead-out terminal 58 to by intermediate frequency resonant tank 57 again.
Antenna resonant tank 52 has and is elements such as the syntonizing coil 52a that is being connected in parallel and variable capacitance diode 52b, and can be by being applied to the tuning voltage at this variable capacitance diode 52b place, tuned frequency is changed, and then select the TV signal of this receiving channels.
Inter-stage resonant tank 54 constitutes by having the humorous loop of polyphony that two structures constitute identical single-tunded circuit, each single-tunded circuit wherein all has and is elements such as the syntonizing coil 54a that is being connected in parallel and variable capacitance diode 54b, and can change its tuned frequency by being applied to the tuning voltage at variable capacitance diode 54b place.
Local oscillator 56 has and is elements such as the syntonizing coil 56a that is being connected in parallel and variable capacitance diode 56b, and can change the frequency (local oscillation frequency) of oscillation signals according by being applied to the tuning voltage at variable capacitance diode 56b place.
And, variable capacitance diode 52b, the variable capacitance diode 54b in the inter-stage resonant tank 54, the variable capacitance diode 56b anode separately in the local oscillator 56 in the antenna resonant tank 52 are connected with the DC earthing current potential, apply shared tuning voltage VT at negative electrode place separately.
Though do not illustrate in the drawings, but the syntonizing coil 52a in the antenna resonant tank 52, the syntonizing coil 54a in the inter-stage resonant tank 54, the syntonizing coil 56a in the local oscillator 56, tuning assembly for TV set receive be the high frequency band TV signal occasion and receive be the occasion of low-frequency band TV signal the time, can implement to switch by different inductance value, what promptly each resonant tank adopted be so-called channel switch type assembly.
Yet in recent years, need make tuning assembly for TV set not only want to receive the conduct TV signal of ripple on the ground, also want to receive cable TV (CATV) signal.And CATV will use as the obsolete frequency band of TV signal of ripple on the ground, for example will use the frequency band that is clamped between high frequency band and the low-frequency band etc.Therefore in recent years for tuning assembly for TV set, wish that its high frequency band frequency reception signal scope and low-frequency band frequency reception signal scope can not be subjected to as the restriction of the band region division of ripple on the ground, so that enlarge their applicable scopes.If be exactly for instance, the corresponding tuning assembly for TV set of CATV with Europe (Germany), its low-frequency band frequency reception signal scope just is taken as 45.5MHz～149.5MHz, and high frequency band frequency reception signal scope is taken as 156.5MHz～426MHz (all referring to its centre frequency here).And in recent years, also make great efforts to enlarge a channel the scope of the frequency reception signal that may receive.
Yet, because the local oscillation frequency of local oscillator 56 exceeds part corresponding to IF-FRE than the frequency (receive frequency) of received TV signal, if so for instance, in aforesaid example (German standard), local oscillation frequency scope when low-frequency band is 82.15MHz～186.15MHz, and the local oscillation frequency scope when high frequency band is 193.15MHz～462.15MHz.
Therefore, the variation of local oscillation frequency ratio is about 2.27 (186.15/82.15) when low-frequency band, and the frequency change of received signal ratio is about 3.29 (149.5/45.5) at this moment; The variation of local oscillation frequency ratio is about 2.39 (462.15/193.15) when high frequency band, and the frequency change of received signal ratio is about 2.72 (426/156.5) at this moment.
Hence one can see that, and when being low-frequency band, the tuning volume change ratio in the local oscillator 56 is 5.15 (=2.27 * 2.27), and the tuning volume change ratio in this moment antenna resonant tank 52 and the inter-stage resonant tank 54 will be 10.8 (=3.29 * 3.29).
Similarly, when being high frequency band, the tuning volume change ratio in the local oscillator 56 is 5.71 (2.39 * 2.39), and the tuning volume change ratio in this moment antenna resonant tank 52 and the inter-stage resonant tank 54 will be 7.40 (=2.72 * 2.72).
And, the tuning volume change ratio of each in antenna resonant tank 52, inter-stage resonant tank 54 and the local oscillator 56, also relevant with the volume change of variable capacitance diode 52b, 54b, 56b.And these variable capacitance diodes 52b, 54b, 56b have identical capacity characteristic.
Therefore, particularly when low-frequency band, can be by effect by tuning voltage VT, make the tuned frequency of antenna resonant tank 52 and the tuned frequency of inter-stage resonant tank 54 locate corresponding to mode in the received signal frequency (for example being 149.5MHz) of highest channel, for example set the tuning characteristic of inter-stage resonant tank 54 by mode shown in Figure 8, and set the loop constant according to making local oscillation frequency locate corresponding to mode in corresponding frequencies (186.15MHz), working as tuning voltage subsequently changes, and when making local oscillation frequency become with the corresponding frequency of lowest channel (for example for 82.15MHz), the tuned frequency of the tuned frequency of antenna resonant tank 52 and inter-stage resonant tank can not drop to the received signal frequency (45.5MHz) of lowest channel always to be located, and promptly can not implement to follow the tracks of to local oscillation frequency.Therefore, the tuning characteristic at lowest channel place will be as shown in Figure 9, thereby have tuned frequency to higher side skew, and make figure transmit degradation problem under the current potential of ripple P.
Tuning assembly for TV set of the present invention can be extended to lower frequency place with the tunable part in the tuned frequency excursion of antenna resonant tank and inter-stage resonant tank, thereby can more easily implement to follow the tracks of to local oscillation frequency.
In order to solve aforesaid problem, a kind of tuning assembly for TV set provided by the invention can dispose has first variable capacitance diode, can change its tuned frequency by the volume change of described first variable capacitance diode, and then select the resonant tank that received signal is used, and has second variable capacitance diode, can change the local oscillator of its local oscillation frequency by the volume change of described second variable capacitance diode, and when changing the voltage that is applied to place, the described first variable capacitance diode two ends respectively and being applied to the voltage at place, the described second variable capacitance diode two ends, the capacity of the capacity of described first variable capacitance diode and described second variable capacitance diode also will change, thereby make the voltage that is applied to place, the described first variable capacitance diode two ends less than the voltage that is applied to place, the described second variable capacitance diode two ends.
And, tuning assembly for TV set of the present invention can also be applied with shared tuning voltage at an end of described first variable capacitance diode and an end place of described second variable capacitance diode, other end place at described first variable capacitance diode is applied with dc offset voltage, and makes the other end of described second variable capacitance diode be in earthing potential.
And, tuning assembly for TV set of the present invention can also be provided with high-frequency amplifier or the frequency mixer that is connected with the rear side of described resonant tank, and be provided with the 3rd variable capacitance diode that combines with described resonant tank, described high-frequency amplifier or frequency mixer, anode place at described the 3rd variable capacitance diode is applied with described dc offset voltage, is applied with described tuning voltage at the negative electrode place of described the 3rd variable capacitance diode.
Below with reference to description of drawings most preferred embodiment of the present invention.
The loop that Fig. 1 uses for expression tv tuning component of the present invention constitutes schematic diagram.
Fig. 2 schematically illustrates figure for what the operating characteristics of the variable capacitance diode of expression in the tuning assembly for TV set of the present invention was used.
The tuning characteristic figure that Fig. 3 uses for explanation tv tuning component of the present invention.
The tuning characteristic figure that Fig. 4 uses for explanation tv tuning component of the present invention.
The detailed loop diagram that Fig. 5 uses for the antenna resonant tank in the expression tuning assembly for TV set of the present invention.
The detailed loop diagram that Fig. 6 uses for the inter-stage resonant tank in the expression tuning assembly for TV set of the present invention.
The loop that Fig. 7 uses for the existing tv tuning component of expression constitutes schematic diagram.
The tuning characteristic figure that Fig. 8 uses for the existing tv tuning component of expression.
The tuning characteristic figure that Fig. 9 uses for the existing tv tuning component of expression.
The structure that Fig. 1 shows a kind of tuning assembly for TV set of the present invention constitutes.As shown in Figure 1, antenna resonant tank 1 is the resonant tank that a kind of TV signal of selecting required channel from the TV signal by input terminal 2 inputs is used, and the TV signal of being selected by this antenna resonant tank 1 inputs to inter-stage resonant tank 4 after high-frequency amplifier 3 amplifies.
Inter-stage resonant tank 4 is a kind of resonant tanks that can further select the TV signal after being amplified by high-frequency amplifier 3 according to selectance characteristic jumpy, and normally constitute by the humorous loop of polyphony.To be input to frequency mixer 5 by the TV signal behind the inter-stage resonant tank 4.The oscillation signals according that is provided by local oscillator 6 also inputs to frequency mixer 5, thereby can in frequency mixer 5 TV signal that receives be transformed to intermediate-freuqncy signal, exports lead-out terminal 8 to by intermediate frequency resonant tank 7 again.
Antenna resonant tank 1 has and is the syntonizing coil 1a that is being connected in parallel and as the elements such as variable capacitance diode 1b of first variable capacitance diode, and locates to be applied with tuning voltage VT at the negative electrode (end) of variable capacitance diode 1b.Anode (other end) at variable capacitance diode 1b locates to be connected with divider resistance 9,10, thereby bias voltage can be applied to this terminal place, this bias voltage is the voltage that is made of after divider resistance 9,10 dividing potential drops the direct voltage that voltage terminal 11 provides.And, be applied to the mode of the tuning voltage VT at negative electrode place among the variable capacitance diode 1b by change, the capacity of variable capacitance diode 1b is changed, and then tuned frequency is changed, thereby select the TV signal that is positioned at receiving channels.
Inter-stage resonant tank 4 constitutes by having the humorous loop of polyphony that two structures constitute identical single-tunded circuit, only shows one of them single-tunded circuit in Fig. 1.Inter-stage resonant tank 4 has and is the syntonizing coil 4a that is being connected in parallel and as the elements such as variable capacitance diode 4b of first variable capacitance diode, and locates to be applied with tuning voltage VT at the negative electrode (end) of variable capacitance diode 4b.Anode (other end) at variable capacitance diode 4b locates to be connected with divider resistance 12,13, thereby bias voltage can be applied to this terminal place, this bias voltage is the voltage that is made of after divider resistance 12,13 dividing potential drops the direct voltage that voltage terminal 11 provides.And, be applied to the mode of the shared tuning voltage VT at negative electrode place among the variable capacitance diode 4b by change, the capacity of variable capacitance diode 4b is changed, and then tuned frequency is changed, thereby select the TV signal that is positioned at receiving channels.
Local oscillator 6 has and is the syntonizing coil 6a that is being connected in parallel and as the elements such as variable capacitance diode 6b of second variable capacitance diode, and locates to be applied with tuning voltage VT at the negative electrode (end) of variable capacitance diode 6b.The anode (other end) of this variable capacitance diode 6b remains same potential with the DC earthing current potential.And, be applied to the mode of the shared tuning voltage VT at negative electrode place among the variable capacitance diode 6b by change, the frequency (local oscillation frequency) of oscillation signals according is changed.
Though do not illustrate in the drawings, but the syntonizing coil 1a in the antenna resonant tank 1, the syntonizing coil 4a in the inter-stage resonant tank 4, the syntonizing coil 6a in the local oscillator 6, tuning assembly for TV set receive be the high frequency band TV signal occasion and receive be the occasion of low-frequency band TV signal the time, can implement to switch by different inductance value, what promptly each resonant tank adopted be so-called channel switch type assembly.
Therefore, for the variable capacitance diode 1b in antenna resonant tank 1, the variable capacitance diode 4b in the inter-stage resonant tank 4, the occasion that variable capacitance diode 6b negative electrode place separately in the local oscillator 6 is applied with shared tuning voltage VT, be applied to the variable capacitance diode 1b in the antenna resonant tank 1 and be applied to the respective cathode of the variable capacitance diode 4b in the inter-stage resonant tank 4, the voltage between the anode, will be lower than the negative electrode that is applied to the variable capacitance diode 6b in the local oscillator 6, voltage between the anode.
Fig. 2 is described this form of implementation, and curve A shows the negative electrode that is applied to variable capacitance diode 1b, 4b, 6b, the voltage between the anode, and the relation between the capacity of this moment.Represented as this curve A, when voltage ratio is low, capacity will sharply increase.And for tuning voltage VT in the scope of VT1 to the VT2 (occasion that changes in the VT1＞VT2), tuning voltage between VT1～VT2 will be applied to by original size between the negative electrode, anode of the syntonizing coil 6a in the local oscillator 6, and the capacity of this moment changes between CT1～CT2, below this excursion is called CT.On the other hand, be applied to separately negative electrode of variable capacitance diode 1b in the antenna resonant tank 1 and the variable capacitance diode 4b in the inter-stage resonant tank 4, the voltage between the anode, compare with the negative electrode, the voltage between the anode of variable capacitance diode 6b in being applied to local oscillator 6, the bias voltage that is applied to the former negative electrode place is reduced to vt1～vt2 respectively.At this moment capacity and voltage vt1～vt2 increase to ct1～ct2 accordingly, and this excursion ct is bigger than excursion CT.
Therefore, the tuned frequency in antenna resonant tank 1 and the inter-stage resonant tank 4 will produce skew to a lower side, thus make for the receive frequency range of high frequency band and low-frequency band extended occasion, also can implement to follow the tracks of to local oscillation frequency.
And, owing to be applied with bias voltage as variable capacitance diode 1b and the anode place separately of the variable capacitance diode 4b in the inter-stage resonant tank 4 first variable capacitance diode, in the antenna resonant tank 1, so only, promptly can increase the capacity of the first variable capacitance diode 1b, 4b simply by the first variable capacitance diode 1b, 4b and second variable capacitance diode 6b negative electrode place separately being applied the mode of shared tuning voltage VT.
If therefore for instance, for the CATV corresponding tuning assembly for TV set of employing with Europe (Germany), be that low-frequency band frequency reception signal scope is 45.5MHz～149.5MHz, high frequency band frequency reception signal scope is the bigger occasion of this setting range of 156.5MHz～426MHz (all referring to its centre frequency here), even with respect to the highest channel receive frequency in the low-frequency band (centre frequency is 149.5MHz), tuned frequency in the inter-stage resonant tank 4 is set in as shown in Figure 3 centre frequency (149.5MHz), also can be as shown in Figure 4, to lowest channel therein frequency of heart (45.5MHz) locate to implement tuning, thereby can obtain good tuning characteristic.Antenna resonant tank 1 also has identical technique effect.
Fig. 5 is the detailed loop diagram of antenna resonant tank 1 usefulness in the expression tuning assembly for TV set of the present invention.As shown in Figure 5, input terminal 11 is connected with not shown antenna etc., and lead-out terminal 12 is connected with high-frequency amplifier 3.Variable capacitance diode 1b as first variable capacitance diode is connected in parallel with the syntonizing coil 13,14,15 that is being connected in series.And syntonizing coil 15 is connected with syntonizing coil 18 by two switching diodes 16,17 that are connected its place, two ends.Wherein, switching diode 16 is to be provided with in the mode that the two ends with syntonizing coil 14 are connected.The anode of these two switching diodes 16,17 is connected with high frequency band switched voltage terminal HB, and negative electrode is connected with low-frequency band switched voltage terminal LB.Negative electrode (end) at variable capacitance diode 1b locates to be applied with tuning voltage VT.Be positioned at anode (other end) on the variable capacitance diode 1b and the tie point between the syntonizing coil 13, be connected with lead-out terminal 12 by variable capacitance diode 19 as the 3rd variable capacitance diode of combination usefulness.The negative electrode of variable capacitance diode 1b is also used capacitor 20 and ground connection by the frequency correction.Therefore, variable capacitance diode 1b and frequency correction are actually with capacitor 20 and are connected in series.Negative electrode (end) at variable capacitance diode 19 locates also to be applied with tuning voltage VT.And also be connected with two divider resistances 21,22 at an end place of syntonizing coil 14, and an end ground connection of divider resistance 21, the other end of divider resistance 22 is connected with negative electrode on the switching diode 16.
If adopt aforesaid structure to constitute, then when receive be the low-frequency band TV signal time, by apply the mode of switched voltage at low-frequency band switched voltage terminal LB place, just can make switching diode 16,17 are in nonconducting state, and then can use variable capacitance diode 1b, frequency correction capacitor 20 and syntonizing coil 13,14,15 constitute resonant tank, and when receive be the high frequency band TV signal time, by apply the mode of switched voltage at high frequency band switched voltage terminal HB place, just can make switching diode 16,17 are in conducting state, make the shorted on both ends of syntonizing coil 14, and syntonizing coil 15 and syntonizing coil 18 are connected in parallel, thereby can use variable capacitance diode 1b, frequency correction capacitor 20 and syntonizing coil 13,15,18 constitute resonant tank.Therefore no matter be for for the occasion of low-frequency band or for being the occasion of high frequency band, switched voltage all is to implement dividing potential drops by divider resistance 21,22, and respectively this branch pressure voltage (bias voltage) is applied to by syntonizing coil 13,14 that variable capacitance diode 1b, 19 anode (other end) separately locates.
Therefore, can reduce the negative electrode that is applied to variable capacitance diode 1b, the voltage between the anode, and increase its capability value.Here, can also implement to revise with the tuning capacity of 20 pairs of whole resonant tanks of capacitor by the frequency correction.
And, in conjunction with also having increased its binding capacity owing to being applied with bias voltage with variable capacitance diode 19, therefore can with high-frequency amplifier 3 as the loop that is connected its back between keep combining more closely, thereby can improve amplification efficient, and improve its NF.
Fig. 6 is the detailed loop diagram of inter-stage resonant tank 4 usefulness in the expression tuning assembly for TV set of the present invention.As shown in Figure 6, inter-stage resonant tank 4 has one-level resonant tank 31 and secondary resonant tank 32, and its input terminal 33 is connected with high-frequency amplifier 3, and lead-out terminal 34 is connected with frequency mixer 5.One-level resonant tank 31 and secondary resonant tank 32 have variable capacitance diode 4b1 and the 4b2 as first variable capacitance diode respectively, the negative electrode (end) of the negative electrode of variable capacitance diode 4b1 (end) and variable capacitance diode 4b2 is used capacitor 35,36 ground connection by the frequency correction that series connection with it is connecting respectively.And, the syntonizing coil 37,38 that is being connected in series and be connected in parallel with capacitor 35 in conjunction with coil 39 and variable capacitance diode 4b1, frequency correction.The syntonizing coil 40,41 that is being connected in series and be connected in parallel with capacitor 36 in conjunction with coil 39 and variable capacitance diode 4b2, frequency correction.End in conjunction with coil 39 passes through divider resistance 43 ground connection, is connected with low-frequency band switched voltage terminal LB by divider resistance 42 in addition.
And, tie point between syntonizing coil 37 and syntonizing coil 38 suppresses to be connected with the anode of capacitor 44 with switching diode 45 by direct current, is connected with the anode of capacitor 46 with switching diode 47 by the direct current inhibition with tie point between the syntonizing coil 41 at syntonizing coil 40. Switching diode 45,47 negative electrode separately is connected with low-frequency band switched voltage terminal LB respectively. Switching diode 45,47 anode separately is connected with high frequency band switched voltage terminal HB respectively.
The anode of variable capacitance diode 4b2 in the secondary resonant tank 32, by being connected with lead-out terminal 34 as the variable capacitance diode 48 of combination with the 3rd variable capacitance diode, and at the negative electrode place of variable capacitance diode 48, the negative electrode place of variable capacitance diode 4b1 in one-level resonant tank 31, and the negative electrode place of the variable capacitance diode 4b2 in secondary resonant tank 32 all is applied with tuning voltage VT.
And be when being positioned at the TV signal of low-frequency band when what receive, by apply the mode of switched voltage at low-frequency band switched voltage terminal LB place, just can make switching diode 45,47 be in nonconducting state, and then can be with syntonizing coil 37,38, constitute the one-level resonant tank that low-frequency band is used in conjunction with coil 39, variable capacitance diode 4b1 and frequency correction with capacitor 35, and similarly, the secondary resonant tank that can use with capacitor 36 formation low-frequency bands with syntonizing coil 40,41, in conjunction with coil 39, variable capacitance diode 4b2 and frequency correction.
When what receive is when being positioned at the TV signal of high frequency band, by apply the mode of switched voltage at high frequency band switched voltage terminal HB place, just can make switching diode 45,47 are in conducting state, make the tie point between syntonizing coil 37 and the syntonizing coil 38, and the tie point high frequency earthing between syntonizing coil 40 and the syntonizing coil 41, thereby can use in conjunction with coil 39, variable capacitance diode 4b1 and frequency correction constitute the one-level resonant tank that high frequency band is used with capacitor 35, and similarly, can use syntonizing coil 40, variable capacitance diode 4b2 and frequency correction constitute the secondary resonant tank that high frequency band is used with capacitor 36.
Therefore, no matter be for for the occasion of low-frequency band or for being the occasion of high frequency band, all be that the frequency band switched voltage is applied to divider resistance 42,43 places, and then will pass through in conjunction with coil 39, syntonizing coil 37,38 by the branch pressure voltage that these divider resistances 42,43 produce, the anode (other end) that is applied on the variable capacitance diode 4b1 is located, locate by the anode (other end) that is applied on the variable capacitance diode 4b2 in conjunction with coil 39, syntonizing coil 40,41 simultaneously, be in bias state with the anode that makes them respectively.
Therefore, can reduce the negative electrode that is applied to variable capacitance diode 4b1, the voltage between the anode, and be applied to the negative electrode of variable capacitance diode 4b2, the voltage between the anode, and increase its capability value.Here, can also the whole tuning capacity of one-level resonant tank 31, secondary resonant tank 32 be implemented to revise by the frequency correction with capacitor 35,36.
And variable capacitance diode 48 has also increased its binding capacity owing to being applied with bias voltage, therefore can with as keeping combining more closely between the frequency mixer 5 that is connected loop thereafter, thereby can improve amplification efficient, and improve its NF.
As mentioned above, a kind of tuning assembly for TV set of the present invention can dispose has first variable capacitance diode, can change its tuned frequency by the volume change of first variable capacitance diode, and then select the resonant tank that received signal is used, and has second variable capacitance diode, can change the local oscillator of its local oscillation frequency by the volume change of second variable capacitance diode, and when changing the voltage that is applied to place, the first variable capacitance diode two ends respectively and being applied to the voltage at place, the second variable capacitance diode two ends, the capacity of the capacity of first variable capacitance diode and second variable capacitance diode also will change, thereby make the voltage that is applied to place, the first variable capacitance diode two ends less than the voltage that is applied to place, the second variable capacitance diode two ends, so can make the tuned frequency of resonant tank produce skew, and then can implement to follow the tracks of to local oscillation frequency to a lower side.
And, tuning assembly for TV set of the present invention can also be applied with shared tuning voltage at an end of first variable capacitance diode and an end place of second variable capacitance diode, other end place at first variable capacitance diode is applied with dc offset voltage, and make the other end of second variable capacitance diode be in earthing potential, so, just can increase the capacity of first variable capacitance diode and the capacity of second variable capacitance diode simply only by applying the mode of shared tuning voltage.
And tuning assembly for TV set of the present invention can also be connected in series with frequency correction capacitor at the first variable capacitance diode place, so can also pass through the mode of the capacity of increase first variable capacitance diode, the tuning capacity of whole resonant tank is implemented to revise.
And, tuning assembly for TV set of the present invention can also be provided with high-frequency amplifier or the frequency mixer that is connected with the rear side of resonant tank, and be provided with and resonant tank, the 3rd variable capacitance diode that high-frequency amplifier or frequency mixer combine, anode place at the 3rd variable capacitance diode is applied with dc offset voltage, negative electrode place at the 3rd variable capacitance diode is applied with tuning voltage, so can increase binding capacity, and then can with as keeping combining more closely between the high-frequency amplifier in the loop of its back segment or the frequency mixer, thereby can improve amplification efficient, and improve its NF.
Claims (3)
1. tuning assembly for TV set, it is characterized in that disposing and have first variable capacitance diode, can change its tuned frequency by the volume change of described first variable capacitance diode, and then select the resonant tank that received signal is used, and has second variable capacitance diode, can change the local oscillator of its local oscillation frequency by the volume change of described second variable capacitance diode, and when changing the voltage that is applied to place, the described first variable capacitance diode two ends respectively and being applied to the voltage at place, the described second variable capacitance diode two ends, the capacity of the capacity of described first variable capacitance diode and described second variable capacitance diode also will change, thereby make the voltage that is applied to place, the described first variable capacitance diode two ends less than the voltage that is applied to place, the described second variable capacitance diode two ends.
2. tuning assembly for TV set as claimed in claim 1, it is characterized in that being applied with shared tuning voltage at an end of described first variable capacitance diode and an end place of described second variable capacitance diode, other end place at described first variable capacitance diode is applied with dc offset voltage, and makes the other end of described second variable capacitance diode be in earthing potential.
3. tuning assembly for TV set as claimed in claim 2, it is characterized in that also being provided with the high-frequency amplifier or the frequency mixer that are connected with the rear side of described resonant tank, and be provided with the 3rd variable capacitance diode that combines with described resonant tank, described high-frequency amplifier or frequency mixer, anode place at described the 3rd variable capacitance diode applies described dc offset voltage, applies described tuning voltage at the negative electrode place of described the 3rd variable capacitance diode.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP020913/1998 | 1998-02-02 | ||
| JP020913/98 | 1998-02-02 | ||
| JP2091398A JPH11220362A (en) | 1998-02-02 | 1998-02-02 | Television tuner |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1231564A true CN1231564A (en) | 1999-10-13 |
| CN1161979C CN1161979C (en) | 2004-08-11 |
Family
ID=12040472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB991004973A Expired - Fee Related CN1161979C (en) | 1998-02-02 | 1999-01-28 | Tuning assembly for television |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH11220362A (en) |
| CN (1) | CN1161979C (en) |
| MY (1) | MY133127A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100384238C (en) * | 2004-04-02 | 2008-04-23 | 华硕电脑股份有限公司 | Electronic apparatus and control method thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3725402B2 (en) * | 2000-03-23 | 2005-12-14 | アルプス電気株式会社 | Television tuner |
| JP2009225411A (en) * | 2008-03-13 | 2009-10-01 | Shintaro Gomi | Broadcast receiver |
-
1998
- 1998-02-02 JP JP2091398A patent/JPH11220362A/en not_active Withdrawn
-
1999
- 1999-01-28 CN CNB991004973A patent/CN1161979C/en not_active Expired - Fee Related
- 1999-02-02 MY MYPI9900353 patent/MY133127A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100384238C (en) * | 2004-04-02 | 2008-04-23 | 华硕电脑股份有限公司 | Electronic apparatus and control method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11220362A (en) | 1999-08-10 |
| MY133127A (en) | 2007-10-31 |
| CN1161979C (en) | 2004-08-11 |
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