CN1652462A - Television tuner and method of processing a received RF signal - Google Patents
Television tuner and method of processing a received RF signal Download PDFInfo
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- CN1652462A CN1652462A CN 200510007958 CN200510007958A CN1652462A CN 1652462 A CN1652462 A CN 1652462A CN 200510007958 CN200510007958 CN 200510007958 CN 200510007958 A CN200510007958 A CN 200510007958A CN 1652462 A CN1652462 A CN 1652462A
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Abstract
A television (TV) tuner includes a first mixer for mixing a received RF signal with a first local oscillating signal to produce an intermediate frequency signal, a second mixer for mixing the intermediate frequency signal with a second local oscillating signal for producing an in-phase baseband output signal, a third mixer for mixing the intermediate frequency signal with a third local oscillating signal for producing a quadrature-phase baseband output signal, the third local oscillating signal being the second local oscillating signal phase delayed, and a single phase locked loop (PLL) coupled to the first mixer, the second mixer, and the third mixer for generating the first local oscillating signal, the second local oscillating signal.
Description
Technical field
The present invention refers in particular to a kind of TV tuner with a single phase-locked loop relevant for TV tuner.
Background technology
In the middle of television system, the cost of tuner (tuner) occupies no small proportion usually in whole cost, and along with the function synthesized with TV slowly increases to the demand among personal computer system's (or other electronic installation), the consideration that the tuner cost is reduced more shows important.In fact, TV tuner can be to be manufactured in earlier on the circuit version, just is installed in the middle of the personal computer system then, so personal computer can also possess the function of TV.This tuner can be transformed into a radio television signal one fundamental frequency (or low frequency) vision signal, and then fundamental frequency (or low frequency) vision signal is sent to other interior elements of personal computer, to carry out follow-up Video processing work.
Fig. 1 is the schematic diagram (United States Patent (USP) the 5th, 737, No. 035) of the TV tuner 100 of known technology.Tuner 100 among Fig. 1 includes a chip circuit (on-chip circuit) 102 and and is positioned at outer (off-chip) band pass filter 104 of chip.Chip circuit 102 includes a low noise amplifier (LNA) 106, one first frequency mixers 108, one second frequency mixers 110, one second intermediate frequency amplifier 112, a plurality of first voltage controlled oscillators 114, one first phase-locked loops 116, one second voltage controlled oscillator 118, and one second phase-locked loop 120.
Owing to used the outer band pass filter 104 of chip, the mirror image repulsion type frequency mixer (as second frequency mixer 110) of special purpose, and a plurality of phase-locked loops control the frequency of each oscillator signal, and the practice of above-mentioned known technology can increase the whole cost and the system complexity of TV tuner 100.
Summary of the invention
So one object of the present invention is to provide a kind of TV tuner with a single phase-locked loop.
The invention discloses a kind of TV tuner, include: one first frequency mixer is used for a selected radiofrequency signal and one first oscillator signal mixing to produce an intermediate-freuqncy signal; One second frequency mixer is used for this intermediate-freuqncy signal and one second oscillator signal mixing to produce an output signal; And a phase-locked loop, be coupled to this first frequency mixer and this second frequency mixer, be used for producing this first oscillator signal and this second oscillator signal, wherein this first oscillator signal and this second oscillator signal are corresponding to this selected radiofrequency signal.
Then include as for a kind of method that is used for handling a received RF signal disclosed in this invention: according to a selected radiofrequency signal, use that first a single voltage controlled oscillator produces one first oscillator signal in the phase-locked loop, use that second a single voltage controlled oscillator produces one second oscillator signal in this phase-locked loop; Should select radiofrequency signal and this first oscillator signal mixing to produce an intermediate-freuqncy signal; And with this intermediate-freuqncy signal and this second oscillator signal mixing to produce an output signal.
Description of drawings
Fig. 1 is the schematic diagram of the TV tuner highly integrated of known technology one.
Fig. 2 is an embodiment schematic diagram of tuner of the present invention.
Fig. 3 is another embodiment schematic diagram of tuner of the present invention.
Fig. 4 is used for handling the method flow diagram of a received RF signal for the present invention.
The main element symbol description
100,200,300 tuners
102 chip circuit
104 band pass filters
106,202 low noise amplifiers
108,110,204,230 frequency mixers
112 intermediate frequency amplifiers
114,118,224,226 voltage controlled oscillators
116,120,218 phase-locked loops
206,212 frequency mixers
208,214,232 low pass filters
210,216 gain amplifiers
220 phase-frequency detectors
222 loop filters
228,304 90 degree phase delay cells
234 frequency dividers (divider)
302,306,310 harmonic mixers
308 45 degree phase delay cells
Embodiment
See also Fig. 2, Fig. 2 is an embodiment schematic diagram of TV tuner of the present invention.TV tuner 200 in the present embodiment includes: a variable gain low-noise amplifier (LNA) 202, one first frequency mixer 204, one homophase frequency mixer (in-phase mixer) 206, one homophase low pass filter 208, one homophase programmable gain amplifier (PGA), 210, one orthogonal mixers, 212, one quadrature low pass filters 214, one quadrature programmable gain amplifier 216, and a single phase-locked loop (PLL) 218.Phase-locked loop 218 includes a phase-frequency detector (PFD) 220, one loop filter 222, one first voltage controlled oscillator 224, one second voltage controlled oscillator 226, one 90 degree phase delay cells 228, one the 4th frequency mixer, 230, one low pass filters 232, and a feedback divider 234 that is used for divided by M.
Variable gain low-noise amplifier 202 can amplify a received RF signal RF_in, and radiofrequency signal after 204 in first frequency mixer will amplify and one first oscillator signal LO1 mixing are to produce an intermediate-freuqncy signal IF (with frequency, IF=LO1-RF).206 of inphase mixers with IF signal and one second oscillator signal LO2 mixing to produce a homophase output signal 207.Next, be responsible for homophase output signal 207 is carried out filtering by homophase low pass filter 208, suppress the outer interference noise of channel, amplify signal that homophase low pass filters 208 are exported to produce a homophase fundamental frequency signal I by homophase programmable gain amplifier 210 again.Similar, orthogonal mixer 212 with IF signal and a signal LO2_90 ° of (the second oscillator signal LO2 is through the result of 90 degree phase delays) mixing to produce a positive blending output signal 213.Next, be responsible for positive blending output signal 213 is carried out filtering, amplify signal that quadrature low pass filters 214 are exported to produce a quadrature baseband signal Q by quadrature programmable gain amplifier 216 again by quadrature low pass filter 214.
In the embodiment of Fig. 2, phase-locked loop 218 is used for producing the first oscillator signal LO1, the second oscillator signal LO2, and signal LO2_90 °.220 comparisons of phase-frequency detector, one reference signal F
REFWith a feedback signal F
FBPhase place, to produce a corresponding error signal 221.The pulse bandwidth of error signal 221 (pulse width) can be used for representing reference signal F
REFWith feedback signal F
FBBetween the size of phase difference.According to the represented reference signal F that goes out of error signal 221
REFWith feedback signal F
FBBetween speed relation, the electric capacity in the loop filter 222 can be recharged or discharge.With regard to its essence, loop filter 222 similar integrators generally carry out work, and accumulation corresponds to a net charge (net charge) of error signal 221.By the loop filter voltage V that loop filter produced
TUNEThen can be used on first voltage controlled oscillator 224 and second voltage controlled oscillator 226.First voltage controlled oscillator 224 and second voltage controlled oscillator 226 can produce first and second oscillator signal LO1, LO2 respectively.And can produce homophase and positive blending output signal simultaneously in order to want, the phase place that 228 of 90 degree phase delay cells can inhibit signal LO2 is to produce LO2_90 ° of signal.Be noted that herein on the implementation, except the practice shown in Figure 2,90 degree phase delay cells can also be arranged at the outside of PLL circuit 228.
Following equation 1 is used for showing the relation between two oscillator signal LO1, LO2 and the selected passage in the RF signal.In equation 1, the frequency of RF representative selected passage in received signal, LO1 is the frequency of first oscillator signal, then is the frequency of second oscillator signal as for LO2.
RF=LO1-LO2 (equation 1)
And first voltage controlled oscillator 224 and second voltage controlled oscillator 226 are for loop filter voltage V
TUNEVariation can have opposite reaction condition, for instance, if loop filter voltage V
TUNEBecome big, the frequency of the first oscillator signal LO1 will increase, and the frequency of the second oscillator signal LO2 then can descend.Frequency change LO1 that following equation 2 and 3 of equations demonstrate the first oscillator signal LO1 respectively and the frequency change LO2 of the second oscillator signal LO2 are with respect to loop filter voltage Δ V
TUNEChange in voltage and the relation between the VCO gain factor K.
LO1 ≈ | K|* Δ V
TUNE(equation 2)
LO2 ≈ (| K|) * Δ V
TUNE(equation 3)
Please note, first voltage controlled oscillator 224 and second voltage controlled oscillator 226 might not have identical VCO gain factor K, and having used identical symbol K in above-mentioned two equations mainly is in order to express first voltage controlled oscillator 224 and second voltage controlled oscillator 226 for loop filter voltage V
TUNEVariation have opposite the Direction of Reaction.Yet, in other embodiment, can also allow first voltage controlled oscillator 224 have one first gain factor K
1, 226 of second voltage controlled oscillators have one second gain factor K
2
The 4th frequency mixer 230 can be with first and second oscillator signal LO1, LO2 mixing to produce a signal 231.Locate to have a higher frequency content in frequency (LO1+LO2) in the signal 231, locate then to have a lower frequency content in frequency (LO1-LO2).The aforementioned frequency content of locating in frequency (LO1+LO2) of 232 responsible filterings of low pass filter, according to the selected passage among the received RF signal RF_in, the frequency content that will locate in frequency (LO1-LO2) is divided by M as for 234 of feedback dividers.Thus, can result from required feedback signal F in the running of phase-locked loop, closed-loop path (closed-loop)
FBShown in the equation 4 that the frequency of selecting passage among the received RF signal RF_in can equal divisor M and be multiplied by reference signal F
REF
Frequency=the F of selected passage
REF* M (equation 4)
Next, PFD 220 can comparison signal F
REFWith feedback signal F
FBPhase place, and the loop filter voltage V that is produced by loop filter 222
TUNEJust can be used to control first and second voltage controlled oscillator 224,226.Because phase-locked loop 218 has the structure of closed-loop path, when arriving stable state, first voltage controlled oscillator 224 and second voltage controlled oscillator 226 will produce the first suitable oscillator signal LO1 and the second oscillator signal LO2, (LO1-LO2) then can be reference signal F
REFM doubly (this is promptly corresponding to the selected passage among the signal RF_in).Then, first frequency mixer 204, second frequency mixer 206 just can become homophase fundamental frequency signal I and quadrature baseband signal Q with conversion (down-convert) under the selected passage among the RF_in with three-mixer 212.
See also Fig. 3, Fig. 3 is another embodiment schematic diagram of tuner of the present invention.TV tuner 300 includes haply similar in appearance to the element of TV tuner 200, and first frequency mixer 204, second frequency mixer 206 and three-mixer 212 that difference is in Fig. 2 have made a first harmonic frequency mixer (harmonic mixer) 302, one a second harmonic frequency mixer 306 and a third harmonic frequency mixer 310 respectively in Fig. 3.In addition, TV tuner 300 also includes one the 2 90 degree phase delay cell 304 and one 45 degree phase delay cells 308.The 2 90 degree phase delay cell 304 can produce the first oscillator signal LO1 through the signal after phase delay 90 degree, and the first oscillator signal LO1 with and all be coupled to first harmonic frequency mixer 302 through the signal after the 90 degree phase delays.In addition, in the embodiments of figure 3, the second oscillator signal LO2 with and all be coupled to second harmonic frequency mixer 306 through 90 degree signal LO2_90 ° after the phase delays.The 45 degree phase delay cell 308 second oscillator signal LO2 that produce then are coupled to third harmonic frequency mixer 310 through phase delay 45 degree and 135 signals of spending.
And actually, first, second, third harmonic mixer 302,306,310 all can use passive harmonic mixer (passive harmonic mixer) to implement.About the operation of harmonic mixer, execution mode, with and characteristics, please refer to the application time and be the patent application " passive harmonic mixer (Passive Harmonic Mixer) " of No. the 10/604018th, U.S. in June, 2003.Owing to used harmonic mixer 302,306 and 310, half frequency got final product when the first oscillator signal LO1 that phase-locked loop 218 is provided and the second oscillator signal LO2 only need provide normal running.These characteristics can reduce phase-locked loop 218 complexity in design.Then please refer to the patent application " based on the TV tuner and the method (HARMONIC MIXER BASED TELEVISION TUNER AND METHOD OF PROCESSING ARECEIVED RF SIGNAL) of handling received RF signal of harmonic mixer " that the application time is No. the 10/707319th, U.S. in December, 2003 as for the mode of operation of TV tuner and characteristics with harmonic structure.
See also Fig. 4 at last, Fig. 4 is the method flow diagram that the present invention is used for handling a received RF signal, and each step among Fig. 4 below will be described in detail in detail:
Step 400: use a single phase-locked loop to produce one first and one second oscillator signal, wherein the frequency of first oscillator signal frequency that deducts second oscillator signal equals the frequency of a selected passage in this received RF signal.Enter step 402.
Step 402: with this received RF signal and the first oscillator signal LO1 mixing to produce an intermediate-freuqncy signal IF.Enter step 404.
Step 404: with intermediate-freuqncy signal IF and the second oscillator signal LO2 mixing producing a homophase fundamental frequency signal, and with intermediate-freuqncy signal IF and the second oscillator signal LO2 through the signal mixing after the phase delay to produce a quadrature baseband signal.
According to the embodiment of the invention described above, because second frequency mixer 206,306 and three-mixer 212,310 can directly be converted to fundamental frequency with the first intermediate-freuqncy signal IF, so do not need to use band pass filter that image signal is removed.In addition, second frequency mixer 206,306 and three-mixer 212,310 can be general frequency mixer.And in tuner of the present invention, use a phase-locked loop 218 to produce oscillator signal LO1, LO2, can reduce the number of elements that tuner uses.
One preferred embodiment, because the outer interference signal of channel just is suppressed up to low pass filter 208,214, so the element of front (low noise amplifier 202, the first frequency mixers 204, orthogonal mixer 212 and inphase mixer 206) have the better linearity degree, can reduce the influence of interference signal.
The above only is the preferred embodiments of the present invention, and all equivalences of carrying out according to claim of the present invention change and revise, and all should belong to covering scope of the present invention.
Claims (10)
1. tuner includes:
One first frequency mixer is used for a selected radiofrequency signal and one first oscillator signal mixing to produce an intermediate-freuqncy signal;
One second frequency mixer is used for this intermediate-freuqncy signal and one second oscillator signal mixing to produce an output signal; And
One phase-locked loop is coupled to this first frequency mixer and this second frequency mixer, is used for producing this first oscillator signal and this second oscillator signal.
2. tuner as claimed in claim 1, wherein this first oscillator signal and this second oscillator signal are corresponding to this selected radiofrequency signal.
3. tuner as claimed in claim 1, wherein this phase-locked loop comprises:
One first voltage controlled oscillator is used for producing this first oscillator signal; And
One second voltage controlled oscillator is used for producing this second oscillator signal.
4. tuner as claimed in claim 3, wherein this first voltage controlled oscillator is opposite for the reaction that variation produced of a control signal with this second voltage controlled oscillator.
5. tuner as claimed in claim 3, wherein this phase-locked loop also comprises:
One phase-frequency detector is used for comparison one reference signal and a feedback signal to produce an error signal;
One loop filter is coupled to this phase-frequency detector, is used for according to this error signal to produce a control signal;
One the 4th frequency mixer, with this first and this second voltage controlled oscillator couple mutually, be used for this first oscillator signal and this second oscillator signal mixing; And
One low pass filter is coupled to the 4th frequency mixer, is used for signal filtering that the 4th frequency mixer is exported.
6. method of handling a received RF signal, this method includes:
According to a selected radiofrequency signal, use a phase-locked loop to produce one first oscillator signal and one second oscillator signal;
Should select radiofrequency signal and this first oscillator signal mixing to produce an intermediate-freuqncy signal; And
With this intermediate-freuqncy signal and this second oscillator signal mixing to produce an output signal.
7. method as claimed in claim 6, wherein the difference on the frequency of this first oscillator signal and this second oscillator signal is corresponding to the frequency of this selected radiofrequency signal.
8. method as claimed in claim 7, wherein the difference on the frequency of this first oscillator signal and this second oscillator signal equals the frequency of this selected radiofrequency signal.
9. method as claimed in claim 6, wherein produce this first and the step of this second oscillator signal also comprise:
Relatively a reference signal and a feedback signal are to produce an error signal;
Produce a control signal according to this error signal;
Produce this first oscillator signal and this second oscillator signal according to this control signal;
With this first oscillator signal and this second oscillator signal mixing; And
The result who draws according to mixing produces this feedback signal.
10. method as claimed in claim 6, wherein this output signal also includes a homophase fundamental frequency signal and a quadrature baseband signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10/708,060 US7120413B2 (en) | 2003-06-22 | 2004-02-06 | Television tuner and method of processing a received RF signal |
| US10/708,060 | 2004-02-06 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1652462A true CN1652462A (en) | 2005-08-10 |
| CN1652462B CN1652462B (en) | 2010-12-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200510007958 Expired - Fee Related CN1652462B (en) | 2004-02-06 | 2005-02-04 | Television tuner and method of processing a received RF signal |
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| Country | Link |
|---|---|
| CN (1) | CN1652462B (en) |
| TW (1) | TWI253856B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8139159B2 (en) | 2006-10-25 | 2012-03-20 | Mstar Semiconductor, Inc. | Single down-conversion television tuner |
| US8139160B2 (en) | 2006-10-25 | 2012-03-20 | Mstar Semiconductor, Inc. | Television tuner with double quadrature mixing architecture |
| US8385855B2 (en) * | 2008-11-07 | 2013-02-26 | Viasat, Inc. | Dual conversion transmitter with single local oscillator |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09512408A (en) * | 1994-12-23 | 1997-12-09 | フィリップス エレクトロニクス ネムローゼ フェンノートシャップ | Combined TV / FM receiver |
| US6400416B1 (en) * | 1999-04-09 | 2002-06-04 | Maxim Integrated Products | Single-chip digital cable TV/cable modem tuner IC |
| JP2002111525A (en) * | 2000-09-29 | 2002-04-12 | Matsushita Electric Ind Co Ltd | Dual-output tuner |
| CN2489526Y (en) * | 2001-07-13 | 2002-05-01 | 安徽四创电子股份有限公司 | Digital integral tuner for direct broadcasting satellite television |
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- 2005-01-25 TW TW94102160A patent/TWI253856B/en active
- 2005-02-04 CN CN 200510007958 patent/CN1652462B/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| TW200527914A (en) | 2005-08-16 |
| CN1652462B (en) | 2010-12-08 |
| TWI253856B (en) | 2006-04-21 |
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Granted publication date: 20101208 Termination date: 20170204 |