CN202034953U - Electronic tuner having image rejection function - Google Patents
Electronic tuner having image rejection function Download PDFInfo
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- CN202034953U CN202034953U CN2010206310456U CN201020631045U CN202034953U CN 202034953 U CN202034953 U CN 202034953U CN 2010206310456 U CN2010206310456 U CN 2010206310456U CN 201020631045 U CN201020631045 U CN 201020631045U CN 202034953 U CN202034953 U CN 202034953U
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- capacitance diode
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Abstract
The utility model provides an electronic tuner having image rejection function, comprising an image rejection circuit, an amplifier and a double tuned circuit, wherein the image rejection circuit is connected with the double tuned circuit through the amplifier to transmit a radiofrequency signal, and the amplifier controls an amplification time via a radiofrequency gain control signal. The image rejection circuit comprises a parallel resonant band pass filter and a series resonant tracking trap filter, the band pass filter is used for transmitting the radiofrequency signal to the double tuned circuit through the amplifier, and the tracking trap filter is used for tracking the image frequency of the radiofrequency signal. According to the utility model, with the original double tuned circuit filtering the image interference, the input side of the radiofrequency signal is added with a tunable tracking trap filter, no matter which channel a TV set receives, the signal on the image frequency point is filtered constantly, such that the image rejection function of the electronic tuner reaches to a higher level.
Description
Technical field
The utility model relates to the electronic tuning unit technology, relates in particular to a kind of electronic tuning unit with mirror image inhibit feature.
Background technology
(be commonly called as: operation principle tuner) is that any one signal that will import becomes a fixing intermediate-freuqncy signal to electronic tuning unit, so during signal F1 of input, to produce the signal of a F1+IF after the tuner local oscillator, two signals enter into frequency mixer simultaneously and handle, because frequency mixer is actually a multiplier, after two signals enter, will generate the signal output of N1 ± N2 state by long-pendingization and difference principle.Therefore, after signal F1 that we need import entered, the local oscillation signal F1+IF mixing with it that tuner produces can obtain the IF signal that we need by (F1+IF)-F1, finishes the effect of tuner frequency reducing.In addition, if the signal F1+2IF on this moment image frequency has also entered into frequency mixer, this signal passes through frequency mixer so, by doing the signal that following computing (F1+2IF)-(F1+IF) also can obtain an IF with local oscillation signal, but this signal is an interference signal in actual applications, and last directly the generation is exactly on the IF Frequency point, so the influence to signal quality is very big, therefore needing the frequency that this is special to test as a content of examination in the tuner standard, is exactly the requirement of so-called image rejection ratio.
Image rejection ratio all is one of important performance indexes of investigating tuner all the time, along with present domestic cable television system is increasingly sophisticated, multiple signal network is also deposited, mirror image disturbs the possibility that occurs to increase greatly, and domestic a plurality of TV manufacturing enterprise carries out the new national standard test request one after another, these are all had higher requirement to the mirror image inhibition ability of tuner, therefore be necessary change by circuit structure, make the mirror image inhibition ability of tuner reach a higher level, to adapt to present market demand.
Summary of the invention
The purpose of this utility model is to provide a kind of electronic tuning unit with mirror image inhibit feature, changes by simple circuit, and the mirror image that effectively improves tuner suppresses ability.
Technical solutions of the utility model are:
The utility model provides a kind of electronic tuning unit with mirror image inhibit feature, comprise: image removing circuit, amplifier and double-tuned circuit, described image removing circuit connects double-tuned circuit with transmitting radio frequency signal by amplifier, described amplifier is by rf gain control signal control multiplication factor, wherein, described image removing circuit comprises the band pass filter of parallel resonance and the tracking trapper of series resonance, described band pass filter is used for radiofrequency signal is transferred to double-tuned circuit by amplifier, and described tracking trapper is used to follow the tracks of the image frequency of radiofrequency signal.
Described electronic tuning unit with mirror image inhibit feature, wherein, described image removing circuit comprises first and second inductance, first to the 3rd electric capacity and first and second variable capacitance diodes, one end of described first inductance is as the rf inputs incoming radio frequency signal, the other end is by the second inductance ground connection, the anode of described first variable capacitance diode is connected between first inductance and second inductance, negative electrode is by first capacity earth and connect the negative electrode of second variable capacitance diode, the anode of described second variable capacitance diode is connected between first inductance and second inductance, negative electrode connects amplifier by second electric capacity, described the 3rd electric capacity is connected between the negative electrode of the end of first inductance and second variable capacitance diode, and the negative electrode of second variable capacitance diode connects tuning voltage.
Described electronic tuning unit with mirror image inhibit feature, wherein, described image removing circuit also comprises first and second resistance, described first resistance is connected between the negative electrode of the negative electrode of described first variable capacitance diode and second variable capacitance diode, and the negative electrode of described second variable capacitance diode connects tuning voltage by second resistance.
Described electronic tuning unit with mirror image inhibit feature, wherein, described double-tuned circuit comprises the 4th to the tenth electric capacity, the the 3rd to the 5th inductance and the 3rd to the 6th variable capacitance diode, one termination amplifier of described the 7th electric capacity, the other end by the 4th electric capacity connect the 3rd variable capacitance diode anode, the negative electrode of the 3rd variable capacitance diode connects the negative electrode of the 4th variable capacitance diode successively by third and fourth inductance, the anode of the 4th variable capacitance diode connects an end of the 6th electric capacity, the other end of the 6th electric capacity is the signal after tuning and by the 9th capacity earth as output output, the tenth electric capacity is connected between the anode and ground of the 3rd variable capacitance diode, the 5th inductance one end is connected between the 3rd inductance and the 4th inductance, another termination tuning voltage is also passed through the 5th capacity earth, the 8th electric capacity one end is connected between the 7th electric capacity and the 4th electric capacity, the other end connects the negative electrode of the 4th capister, the negative electrode of the 6th variable capacitance diode connects the negative electrode of the 4th variable capacitance diode, plus earth.
Described electronic tuning unit with mirror image inhibit feature, wherein, described double-tuned circuit also comprises the 3rd to the 5th resistance, described the 5th inductance connects tuning voltage by the 3rd resistance, described the 4th resistance is in parallel with the tenth electric capacity, and described the 5th resistance is connected between the anode and ground of the 4th variable capacitance diode.
Described electronic tuning unit with mirror image inhibit feature, wherein, described amplifier is the bigrid metal-oxide-semiconductor, and one of its grid connects image removing circuit, and another connects the rf gain control signal.
The utility model is when disturbing original double-tuned circuit filtering mirror image, add a tunable tracking trapper at the radiofrequency signal input side, which channel tube television receiver does not receive, all the time the target signal filter on its image frequency point is fallen, make the mirror image inhibition ability of electronic tuning unit reach a higher level.
Description of drawings
Fig. 1 is the circuit diagram that the utlity model has the electronic tuning unit better embodiment of mirror image inhibit feature;
Fig. 2 is the equivalent circuit diagram of image removing circuit among Fig. 1.
Embodiment
In order to make the purpose of this utility model, technical scheme and advantage clearer,, the utility model is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.
With reference to figure 1, the electronic tuning unit better embodiment that the utlity model has the mirror image inhibit feature comprises: image removing circuit 12, amplifier 14 and double-tuned circuit 16, as shown in the figure, shown in image removing circuit 12 comprise inductance L 1 and L2, capacitor C 1～C3, resistance R 1 and R2 and variable capacitance diode BB1 and BB2, one end of described inductance L 1 is as rf inputs RF IN incoming radio frequency signal, the other end is by inductance L 2 ground connection, the anode of described variable capacitance diode BB1 is connected between inductance L 1 and the L2, negative electrode is by capacitor C 1 ground connection and connect the negative electrode of variable capacitance diode BB2 by resistance R 1, the anode of described variable capacitance diode BB2 is connected between inductance L 1 and the L2, negative electrode connects amplifier 14 by capacitor C 2, described capacitor C 3 is connected between the negative electrode of end of inductance L 1 and variable capacitance diode BB2, and the negative electrode of variable capacitance diode BB2 also meets tuning voltage Vtu by resistance R 2.
Described amplifier 14 is bigrid metal-oxide-semiconductor MOSFET, one of its grid connects the capacitor C 2 in the described image removing circuit 12, another meets rf gain control signal RFAGC, grounded drain, source electrode connects double-tuned circuit 16, is being transferred to double-tuned circuit 16 after the output signal amplification with image removing circuit 12 under the control that meets rf gain control signal RFAGC.
Described double-tuned circuit 16 is for having the coupling circuit of two tuning circuits, it comprises capacitor C in, Cf, CL, Cc and C4～C6, resistance R 3～R5, inductance L 3～L5 and variable capacitance diode BB3～BB6, the termination amplifier 14 of described capacitor C in, the other end by capacitor C 4 connect variable capacitance diode BB3 anode, the negative electrode of variable capacitance diode BB3 connects the negative electrode of variable capacitance diode BB4 successively by inductance L 3 and L4, the anode of variable capacitance diode BB4 connects capacitor C 6 one ends, capacitor C 6 other ends are the signal after tuning as output OUT output, building-out capacitor Cc and resistance R 4 are parallel between the anode and ground of variable capacitance diode BB3, inductance L 5 one ends are connected between inductance L 3 and the L4, the other end meets tuning voltage Vtu and passes through capacitor C 5 ground connection by resistance R 3 respectively, capacitor C f one end is connected with the other end of capacitor C in, the other end connects the negative electrode of capister BB4, the negative electrode of variable capacitance diode BB6 connects the negative electrode of variable capacitance diode BB4, plus earth, resistance R 5 is connected between the anode and ground of variable capacitance diode BB4, and capacitor C L is connected between output OUT and the ground.
The circuit design of above-mentioned double-tuned circuit 16 has the conversion of good resonance characteristic, impedance also very convenient.Wherein inductance L 3～L5 is the equivalent relation of mutual inductance coupling T type circuit, by changing the value of inductance L 5, can change degree of coupling very easily, adopt variable capacitance diode BB5 and BB6 and inductance L 3～L5 to form basic resonant circuit in the circuit, by adjusting tuning voltage Vtu the electric capacity of variable capacitance diode BB5 and BB6 is changed and to change resonance point, thereby reach the purpose of channel selection, described variable capacitance diode BB3 and BB4 are used to finely tune impedance variation, the fluctuation of balance equivalence input and output in broadband range, resistance R 4 and R5 are current-limiting resistance. capacitor C c is a building-out capacitor, make level resonance frequency unanimity before and after higher frequency place, capacitor C 6 is an impedance matching electric capacity, the effect of capacitor C 4 can also be regulated change mirror image inhibition point except making impedance matching.
In foregoing circuit, the capacitance of establishing variable capacitance diode BB3～BB6 is respectively C
V3, C
V4, C
V5, C
V6, band resistance dot frequency value satisfies formula as can be known:
This band resistance dot frequency is mirror image inhibition point frequency, by top formula as can be seen: the change of mirror image blanketing frequency is mainly decided by capacitor C 4 and Cf, and in engineering is used, capacitor C 4 adopts patch capacitor usually, and capacitor C f is because the appearance value is very little, generally adopt the microstrip line in the printed board to realize, and do not have the instrument of accurate its numerical value of emulation at present, often can not all carry out good restraining in actual the use the mirror image interference of all channels.So also need in the input circuit of electronic tuning unit, increase the mirror image inhibition ability that image removing circuit 12 promotes tuner
So also need in the input circuit of tuner, increase the mirror image inhibition ability that image removing circuit 12 promotes tuner, suppress the equivalent electric circuit of circuit 12 with reference to figure 2 for above-mentioned image.The equivalent electric circuit that above-mentioned image suppresses circuit 12 is one and forms a tunable band pass filter by variable capacitance C and inductance L 2 (parallel resonance), makes useful signal enter the passage of back completely; And variable capacitance C and inductance L 1 (series resonance) form a tunable tracking trapper, and its principle is to use the tuning voltage Vtu of tuner to adjust the capacitance of variable capacitance C to realize the tracking of this band pass filter and image frequency.
After using this circuit, the image rejection ratio of electronic tuning unit can reach more than the 65dB, is example with 487MHz, and this circuit not only can allow harmless the passing through of useful signal F1=487MHz, and the signal attenuation of its image frequency 563MHz reaches 70dB; Adjust two capacitances of variable capacitance diode BB1 and BB2, the simulation tuner be tuned to higher frequency, again to band pass filter and after being with the resistance point to carry out emulation, can find the resonance point frequency of band pass filter and the absorption frequency basically identical that band hinders point, all obtain good tracking.
The utility model is when disturbing original double-tuned circuit filtering mirror image, also add a tunable tracking trapper at the radiofrequency signal input side, which channel tube television receiver does not receive, all the time the target signal filter on its image frequency point is fallen, make its mirror image inhibition ability reach a higher level.
Should be understood that; the above only is a better embodiment of the present utility model; not in order to limit protection range of the present utility model; for those of ordinary skills; any modification of being done according to the above description, be equal to and replace and improvement etc., all should be included within the protection range of the present utility model.
Claims (6)
1. electronic tuning unit with mirror image inhibit feature, comprise: image removing circuit, amplifier and double-tuned circuit, described image removing circuit connects double-tuned circuit with transmitting radio frequency signal by amplifier, described amplifier is by rf gain control signal control multiplication factor, it is characterized in that: described image removing circuit comprises the band pass filter of parallel resonance and the tracking trapper of series resonance, described band pass filter is used for radiofrequency signal is transferred to double-tuned circuit by amplifier, and described tracking trapper is used to follow the tracks of the image frequency of radiofrequency signal.
2. the electronic tuning unit with mirror image inhibit feature according to claim 1, it is characterized in that, described image removing circuit comprises first and second inductance, first to the 3rd electric capacity and first and second variable capacitance diodes, one end of described first inductance is as the rf inputs incoming radio frequency signal, the other end is by the second inductance ground connection, the anode of described first variable capacitance diode is connected between first inductance and second inductance, negative electrode is by first capacity earth and connect the negative electrode of second variable capacitance diode, the anode of described second variable capacitance diode is connected between first inductance and second inductance, negative electrode connects amplifier by second electric capacity, described the 3rd electric capacity is connected between the negative electrode of the end of first inductance and second variable capacitance diode, and the negative electrode of second variable capacitance diode connects tuning voltage.
3. the electronic tuning unit with mirror image inhibit feature according to claim 2, it is characterized in that, described image removing circuit also comprises first and second resistance, described first resistance is connected between the negative electrode of the negative electrode of described first variable capacitance diode and second variable capacitance diode, and the negative electrode of described second variable capacitance diode connects tuning voltage by second resistance.
4. the electronic tuning unit with mirror image inhibit feature according to claim 1, it is characterized in that, described double-tuned circuit comprises the 4th to the tenth electric capacity, the the 3rd to the 5th inductance and the 3rd to the 6th variable capacitance diode, one termination amplifier of described the 7th electric capacity, the other end by the 4th electric capacity connect the 3rd variable capacitance diode anode, the negative electrode of the 3rd variable capacitance diode connects the negative electrode of the 4th variable capacitance diode successively by third and fourth inductance, the anode of the 4th variable capacitance diode connects an end of the 6th electric capacity, the other end of the 6th electric capacity is the signal after tuning and by the 9th capacity earth as output output, the tenth electric capacity is connected between the anode and ground of the 3rd variable capacitance diode, the 5th inductance one end is connected between the 3rd inductance and the 4th inductance, another termination tuning voltage is also passed through the 5th capacity earth, the 8th electric capacity one end is connected between the 7th electric capacity and the 4th electric capacity, the other end connects the negative electrode of the 4th capister, the negative electrode of the 6th variable capacitance diode connects the negative electrode of the 4th variable capacitance diode, plus earth.
5. the electronic tuning unit with mirror image inhibit feature according to claim 4, it is characterized in that, described double-tuned circuit also comprises the 3rd to the 5th resistance, described the 5th inductance connects tuning voltage by the 3rd resistance, described the 4th resistance is in parallel with the tenth electric capacity, and described the 5th resistance is connected between the anode and ground of the 4th variable capacitance diode.
6. according to the described electronic tuning unit with mirror image inhibit feature of arbitrary claim in the claim 1 to 5, it is characterized in that described amplifier is the bigrid metal-oxide-semiconductor, one of its grid connects image removing circuit, and another connects the rf gain control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206310456U CN202034953U (en) | 2010-11-26 | 2010-11-26 | Electronic tuner having image rejection function |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010206310456U CN202034953U (en) | 2010-11-26 | 2010-11-26 | Electronic tuner having image rejection function |
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| CN202034953U true CN202034953U (en) | 2011-11-09 |
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| CN2010206310456U Expired - Lifetime CN202034953U (en) | 2010-11-26 | 2010-11-26 | Electronic tuner having image rejection function |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102497519A (en) * | 2011-11-30 | 2012-06-13 | 重庆大学 | Ultrahigh frequency high image rejection filter |
| CN104469216A (en) * | 2015-01-04 | 2015-03-25 | 安徽波维电子科技有限公司 | C-band tuner facilitating noise coefficient regulation |
| TWI757111B (en) * | 2021-03-05 | 2022-03-01 | 瑞昱半導體股份有限公司 | Transmitter |
| WO2023098918A1 (en) * | 2021-11-30 | 2023-06-08 | 东南大学 | Second-order adjustable lc notch filter for pole zero tracking |
-
2010
- 2010-11-26 CN CN2010206310456U patent/CN202034953U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102497519A (en) * | 2011-11-30 | 2012-06-13 | 重庆大学 | Ultrahigh frequency high image rejection filter |
| CN102497519B (en) * | 2011-11-30 | 2014-04-16 | 重庆大学 | Ultrahigh frequency high image rejection filter |
| CN104469216A (en) * | 2015-01-04 | 2015-03-25 | 安徽波维电子科技有限公司 | C-band tuner facilitating noise coefficient regulation |
| TWI757111B (en) * | 2021-03-05 | 2022-03-01 | 瑞昱半導體股份有限公司 | Transmitter |
| WO2023098918A1 (en) * | 2021-11-30 | 2023-06-08 | 东南大学 | Second-order adjustable lc notch filter for pole zero tracking |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 516006 Guangdong province Huizhou Zhongkai hi tech Development Zone No. 75 District Co-patentee after: HUIZHOU TECHNE Corp. Patentee after: HUIZHOU GAOSHENGDA TECHNOLOGY Co.,Ltd. Address before: 516006 Guangdong province Huizhou Zhongkai hi tech Development Zone No. 75 District Co-patentee before: HUIZHOU TECHNE Corp. Patentee before: Huizhou TCL King High Frequence El. Co.,Ltd. |
|
| CP01 | Change in the name or title of a patent holder | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20170705 Address after: 516006 Guangdong province Huizhou City Zhongkai high tech Development Zone Patentee after: HUIZHOU GAOSHENGDA TECHNOLOGY Co.,Ltd. Address before: 516006 Guangdong province Huizhou Zhongkai hi tech Development Zone No. 75 District Co-patentee before: HUIZHOU TECHNE Corp. Patentee before: HUIZHOU GAOSHENGDA TECHNOLOGY Co.,Ltd. |
|
| TR01 | Transfer of patent right | ||
| CX01 | Expiry of patent term |
Granted publication date: 20111109 |
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| CX01 | Expiry of patent term |