CN101803108A - A tuneable bandpass filter - Google Patents
A tuneable bandpass filter Download PDFInfo
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- CN101803108A CN101803108A CN200880108005A CN200880108005A CN101803108A CN 101803108 A CN101803108 A CN 101803108A CN 200880108005 A CN200880108005 A CN 200880108005A CN 200880108005 A CN200880108005 A CN 200880108005A CN 101803108 A CN101803108 A CN 101803108A
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- 238000006880 cross-coupling reaction Methods 0.000 claims description 3
- 230000004044 response Effects 0.000 description 11
- 238000003780 insertion Methods 0.000 description 9
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
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Abstract
A tuneable bandpass filter comprising a plurality of coupled resonators, the filter comprising a common structure comprising at least one common coupling (44) or one common resonator (7); an upper loop (8) comprising first and second end resonators coupled together by a signal path, the loop further comprising at least one further signal path extending between end resonators, the further signal path comprising at least one further resonator, the end resonators being coupled to the common structure; a lower loop (18) comprising first and second end resonators coupled together by a signal path, the loop further comprising at least one further signal path extending between end resonators, the further signal path comprising at least one further resonator, the end resonators being coupled to the common structure; the resonators being coupled together such that the bandpass filter can be divided into a low pass sub filter and a high pass sub filter, one of the sub filters being arranged to receive the output of the other.
Description
Technical field
The present invention relates to variable band-pass filter.Specifically and not exclusively, the present invention relates to variable band-pass filter, it comprises the resonator of a plurality of couplings, described resonator is disposed in first and second loops, each of described first and second loops is connected to public structure, described resonator is arranged and makes described filter can be broken down into low pass and high pass subfilter, and a subfilter is arranged the output that receives another subfilter.
Background technology
There are following many demands, require when reservation definitely suppresses to require with respect to fixing of band edge the next tuning filter of the control of use on bandwidth of operation and frequency according to the resonator configurations that is coupled.Use known comprehensive and implementation method, tuning band pass filter with variable frequency and bandwidth will require the resonance frequency and the connection of the coupling between each resonator (coupling) of tuned resonator, and will only satisfy and suppress requirement relatively.This causes implementing complicated filter.
Summary of the invention
Variable band-pass filter according to the present invention seeks to overcome this problem.
Therefore, the invention provides a kind of variable band-pass filter, it comprises the resonator of a plurality of couplings, and described filter comprises:
Public structure, it comprises at least one public coupling connection or a public resonator;
Last loop, it comprises the first and second terminal resonators that are coupled by signal path, described loop also is included at least one the other signal path that extends between the terminal resonator, described other signal path comprises the resonator that at least one is other, and described terminal resonator is coupled to described public structure;
Following loop, it comprises the first and second terminal resonators that are coupled by signal path, described loop also is included at least one the other signal path that extends between the terminal resonator, described other signal path comprises the resonator that at least one is other, and described terminal resonator is coupled to described public structure;
Described each resonator is coupled, so that described band pass filter can be divided into low pass subfilter and high pass subfilter, one of described subfilter is arranged to the output that receives another subfilter.
Variable band-pass filter according to the present invention has the bandwidth and the centre frequency of band-pass response, can only come tuning described band-pass response by tuning described each resonator, and needn't be adjusted at the coupling connection between each resonator.
Described public structure can comprise single public resonator, and the described described terminal resonator of going up loop and following loop is connected to described public resonator.
Described low pass subfilter can comprise described public resonator and the described resonator in loop down.
Described high pass subfilter can comprise described public resonator and the described resonator of going up the loop.
Alternatively, described public structure can be included in the described a plurality of public coupling connection that is coupled between loop and the following loop of going up.
Described public coupling connection can be arranged such that each terminal resonator in a loop all is coupled to two terminal resonators in another loop.
Described upward loop can comprise the resonator of even number.
Alternatively, described upward loop can comprise the resonator of Odd number.
Described loop down can comprise the resonator of even number.
Alternatively, described loop down can comprise the resonator of Odd number.
Described at least one that goes up loop and following loop can comprise a plurality of resonators that are coupled.
At least one of described loop can comprise a plurality of resonators that are coupled with cascade system, so that many signal path are arranged between the terminal resonator.
The described resonator of at least some of described at least one loop can be coupled in cross-linked step configuration mode.
At least some resonators with the cross-couplings step configuration can also comprise: the intersection coupling connection at least one diagonal angle of the resonator on the adjacent cross-linked ladder rungs.
Described filter can also comprise the disresonance input circuit node, and this node is coupled to the terminal resonator in one of described loop.
Described filter can also comprise the group delay equalizing network, described group delay equalizing network also be coupling in input circuit node and with terminal resonator that this node is connected between.
Described filter can also comprise the output circuit node, and described output circuit node is coupled to the terminal resonator in another loop.
Described filter can also comprise the group delay equalizing network, described group delay equalizing network be connected described output circuit node and with terminal resonator that this node is connected between.
Description of drawings
With reference now to accompanying drawing, only pass through example, rather than the present invention is described with any limited significance, wherein:
Fig. 1 (a) and 1 (b) show the known coupled resonators band pass filter of the resonator of the coupling with even number and Odd number respectively;
Fig. 2 shows first embodiment according to variable band-pass filter of the present invention;
Fig. 3 shows the equivalent electric circuit of the filter of Fig. 2;
Fig. 4 shows the diagram with respect to the insertion loss of frequency of the filter of Fig. 2;
Fig. 5 shows second embodiment according to variable band-pass filter of the present invention;
Fig. 6 shows the equivalent electric circuit of the filter of Fig. 5;
Fig. 7 shows the equivalent electric circuit according to another embodiment of filter of the present invention;
Fig. 8 shows according to the filter of the present invention with equivalent electric circuit of Fig. 7; And
Fig. 9 shows another embodiment according to filter of the present invention.
Embodiment
The band pass filter that is in radio frequency and microwave frequency is implemented as the network of the resonant circuit that is coupled each other by resonant circuit usually.In Fig. 1 (a) and 1 (b), such known band pass filters 1 has been shown.Filter 1 comprises a plurality of resonators 2 separately.Resonator 2 with shown in the cross-couplings step configuration be coupled.Input and output connection to band pass filter 1 is by non-resonant circuit node 3,4.
Comprehensive these networks are known to produce any asymmetric response.Can on either direction, produce and be shown as cornerwise coupling connection original paper.
Determine the center of the passband of filter 1 by the resonance frequency of resonator 2, and the general type of determining described response by the ratio and the topology of coupling connection.Can realize changing the centre frequency of filter 1 by the resonant frequency that only changes resonator 2.The relative bandwidth that changes filter 1 requires to be modified in the frequency of the coupling connection resonator 2 between the resonator 2.Such filter 1 trends towards making and uses too complicated, and if unmodified coupling connection then generally will only keep the relative selectivity requirement.
Can be by on the coupling connection matrix of filter 1, using the version that rotation transformation is implemented in the unlimited amount of the structure among Fig. 1.
Figure 2 illustrates according to variable band-pass filter 5 of the present invention.Filter 5 comprises public structure 6, and public structure 6 comprises single public resonator 7.Filter 5 comprises loop 8, and last loop 8 comprises the first and second terminal resonators 9,10 that are coupled by signal path 11. Terminal resonator 9,10 also is coupled to public resonator 7 separately.Last loop 8 also comprises a plurality of other resonator 12-15, and described a plurality of other resonator 12-15 are coupled along a plurality of signal paths 16 between terminal resonator 9,10. Resonator 9,10, the 12-15 in last loop 8 are coupled in cross-linked step configuration mode.Can be at the connection of the diagonal coupling between the resonator that is created on the either direction on the different steps 16.Be shown in dotted line the unit that repeats.In this embodiment, last loop 8 comprises 6 resonators, yet other embodiment with resonator of 8,10,12 etc. also are possible.Disresonance output signal node 17 is coupled to a terminal resonator 10 in loop 8.
Figure 3 illustrates the equivalent electric circuit 28 of the variable band-pass filter 5 of Fig. 2.In equivalent electric circuit 28, variable band-pass filter 5 is divided into two subfilters 29,30 that link together at disresonance node 31 places.Similar Reference numeral indication variable band-pass filter 5 and the similar resonator in the equivalent electric circuit 28 thereof.One of subfilter 29 comprises low pass subfilter 29, and it has the low pass band edge at frequency w1.Another subfilter 30 comprises high pass subfilter 30, and it has the upper passband edge at frequency w2.Equivalent electric circuit 28 comprises a resonance node than variable band-pass filter more than 5.This is because by first resonator 7 of low pass subfilter 29 and first resonator, 7 merging of high pass subfilter 30 have been formed public resonator 7.
The insertion loss of variable band-pass filter 5 is combinations of the insertion loss of the low pass of equivalent electric circuit 28 and high pass subfilter 29,30.Fig. 4 shows the insertion loss of the subfilter 29,30 of the insertion loss of variable band-pass filter 5 and its equivalent electric circuit 28, and this has considered both interactions.When the band edge of low pass subfilter 29 was in the higher frequency of band edge than high pass subfilter 30, the insertion loss of combination comprised with w
0Be the logical zone of band at center, described w
0Have at w respectively
1And w
2The edge.
Can be independent of in fact each other and change low pass and high pass subfilter 29,30.Therefore, in order to change band edge down, adjust the resonance frequency of the resonator 7,9,10,12,13,14,15 of variable band-pass filter 5, this variable band-pass filter 5 comprises the high pass subfilter 30 of equivalent electric circuit 28.To go up band edge in order changing, to adjust the resonance frequency of the resonator of variable band-pass filter 5, this variable band-pass filter 5 comprises the low pass subfilter 29 of equivalent electric circuit 28.By adjusting band edge up and down, can only adjust the center and the width in the logical zone of band of variable band-pass filter 5, and needn't be adjusted at the coupling connection between the resonator by the resonance frequency of adjusting resonator.This compares with known band pass filter and has reduced the complexity of variable band-pass filter 5 widely and improved the easiness of its use, and has kept identical absolute selectivity.
The variable band-pass filter 5 of this embodiment has high symmetry usually.Because the symmetry of filter 5, public resonator 7 is adjusted to the center of filter passband usually.In order to change bandwidth (constant centre frequency), adjust all resonators except public resonator 7.
In an alternate embodiment (not shown) of the present invention, variable band-pass filter 5 is asymmetric, and can be broken down into n
LThe low pass subfilter 29 and the n of level
HThe high pass subfilter 30 of level.For such filter 5, must adjust n
LIndividual resonator is with mobile lower limb, and adjustment n
HIndividual resonator is with mobile top edge (comprising public resonator 7).In order to move the centre frequency of response, must change all resonators.
Figure 5 illustrates another embodiment according to variable band-pass filter 5 of the present invention.In this embodiment, last loop and following loop 8,18 comprise the resonator of Odd number.In the equivalent electric circuit shown in Fig. 6 28, two resonators that subfilter 29,30 has even number.And two subfilters 29,30 are respectively low pass 29 and high pass 30 subfilters.
In all the foregoing descriptions of the present invention, the low pass of equivalent electric circuit 28 and high pass subfilter 29,30 have two transmission zeros at infinite place.But this is dispensable.Figure 7 illustrates the equivalent electric circuit 28 of tunable filter 5, wherein, low pass and high pass subfilter 29,30 only have a transmission zero at infinite place.When satisfying design specification, produce other flexibility from one of infinite mobile transmission zero.Low pass and high pass subfilter 29,30 link together by two disresonance nodes 42,43 now.
Figure 8 illustrates the topology of variable band-pass filter 5.As the preceding embodiment, filter 5 comprises and comprises loop and following loop 8,18 on a plurality of resonators separately.But public structure 6 is more complicated.In this embodiment, public structure 6 comprises a plurality of public couplings connection 44, the terminal resonator 45,46,51,52 in loop and following loop 8,18 on described a plurality of public couplings connection 44 are arranged to fully be coupled.Each terminal resonator 45,46,51,52 in a loop 8,18 is coupled to two terminal resonators 45,46,51,52 in another loop 8,18.
The variable band-pass filter 5 of Fig. 8 has kept the identical base attribute according to another variable band-pass filter 5 of the present invention.Particularly, can realize the independent adjustment of band pass filter bandwidth and centre frequency by adjusting relevant resonator.Not needing to be adjusted at coupling between the resonator joins and adjusts centre frequency or bandwidth.
Figure 9 illustrates another embodiment according to variable band-pass filter 5 of the present invention.Desirable filter will transmit the signal in the frequency band of expectation in all undesired signals of decay, and will only have constant change on amplitude and constant time delay for the signal of expectation.If the different frequency component of composite signal arrived in the different time, then described signal is with distortion.The requirement of constant time-delay is equal to the needs for constant group delay.The absolute level that postpones is normally unessential, importantly, and the variation of the delay on signal bandwidth.
The embodiment of the filter 5 of Fig. 9 also comprises compensation group delay equalizing network 57, except input disresonance electrode 27 and with resonator 37 that input node 27 is connected between direct coupling join, go back the between compensation group delay equalizing network 57 that has been coupled.Compensation group delay equalizing network 57 comprises a plurality of resonators 58,59 that are cascaded.Another compensation group delay equalizing network 60 be coupling in output disresonance node 17 and and the resonator 32 of output node 17 couplings between.And it comprises a plurality of resonators 61,62 of series connection.And it is in parallel with the direct coupling connection between output node 17 resonator 32.The response of compensation group delay equalizing network 57,60 is with respect to the carrier deviation of the band-pass response of expectation, so as each compensating network 57,60 for half influence of bandwidth greater than influence for second half.The group delay peak value of compensation group delay equalizing network 57,60 appears at the nominal center frequency of Compensation Design.In order to compensate in the group delay at band-pass response center, the nominal center frequency of compensator appears in the passband of band-pass response.For to the correct compensation of described response application, they must be arranged symmetrically around the centre frequency of band-pass response, select requirement to satisfy symmetric amplitudes.
Can tuning compensation group delay equalizing network 57,60.Compensation group delay equalizing network 57,60 is suitable for coming the tuning of tracking filter 5 by following manner: overlapping with respect to the low pass of variable band-pass filter 5 and high pass subfilter 29,30, and the frequency of compensation group delay equalizing network 57,60 is synchronous with the centre frequency of skew correctly.
If with respect to the overlapping centre frequency that changes compensation group delay equalizing network 57,60 of low pass and high pass subfilter 29,30, then can change the relative position of compensation rate and group delay ripple.
Compensation group delay equalizing network 57,60 can be used to reduce the group delay variations of all bandwidth adjusted.Except reducing group delay variations, the variation in the insertion loss in compensating network 57,60 has also reduced the variation of the insertion loss on passband, though its cost is to have improved minimum insertion loss.
The low pass subfilter 29 of above equivalent electric circuit 28 must be following band pass filter, and the stopband that its performance is customized to help on the passband of variable band-pass filter 5 suppresses, and considers the performance under the passband of variable band-pass filter 5 hardly.Such filter 29 often is called as " standard " low pass filter.
Similarly, the high pass subfilter 30 of equivalent electric circuit 28 must be following band pass filter, and the stopband that its performance is customized to help under the passband of variable band-pass filter 5 suppresses, and considers the performance on the passband of variable band-pass filter 5 hardly.Such filter 30 often is called as " standard " high pass filter.
Variable band-pass filter 5 according to the present invention has resonator usually, and described resonator is created in the passband in the microwave region at microwave frequency resonance.Usually, described resonator comprises the cavity resonator (not shown), and it comes tuning by the tuning member of replacing in the cavity.Usually the hole of the common wall by extending through two cavitys two variable cavities that are coupled.
In all the foregoing descriptions, the resonator of variable band-pass filter links together with following layout: described layout makes can be used as described filter as accurate high pass subfilter and the accurate low pass subfilter that links together, and one of them receives another output.In these embodiments, the output of a subfilter is connected to another input by a plurality of disresonance nodes, and the quantity of node depends on the exponent number of subfilter.
Claims (20)
1. variable band-pass filter, it comprises the resonator of a plurality of couplings, described filter comprises:
Public structure, it comprises at least one public coupling connection or a public resonator;
Last loop, it comprises the first and second terminal resonators that are coupled by signal path, described loop also is included at least one the other signal path that extends between the terminal resonator, described other signal path comprises the resonator that at least one is other, and described terminal resonator is coupled to described public structure;
Following loop, it comprises the first and second terminal resonators that are coupled by signal path, described loop also is included at least one the other signal path that extends between the terminal resonator, described other signal path comprises the resonator that at least one is other, and described terminal resonator is coupled to described public structure;
Described each resonator is coupled, so that described band pass filter can be divided into low pass subfilter and high pass subfilter, one of described subfilter is arranged to the output that receives another subfilter.
2. according to the variable band-pass filter of claim 1, wherein, described public structure comprises single public resonator, and the described described terminal resonator of going up loop and following loop is connected to described public resonator.
3. according to the variable band-pass filter of claim 2, wherein, described low pass subfilter comprises described public resonator and described each resonator in loop down.
4. according to the variable band-pass filter of claim 2 or 3, wherein, described high pass subfilter comprises described public resonator and described each resonator of going up the loop.
5. according to the variable band-pass filter of claim 1, wherein, described public structure is included in the described a plurality of public coupling connection that is coupled between loop and the following loop of going up.
6. according to the variable band-pass filter of claim 5, wherein, described each public coupling connection is arranged such that each terminal resonator in loop all is coupled to two terminal resonators in another loop.
7. according to any one variable band-pass filter of claim 1-6, wherein, described upward loop comprises the resonator of even number.
8. according to any one variable band-pass filter of claim 1-6, wherein, described upward loop comprises the resonator of Odd number.
9. according to any one variable band-pass filter of claim 1-8, wherein, described loop down comprises the resonator of even number.
10. according to any one variable band-pass filter of claim 1-8, wherein, described loop down comprises the resonator of Odd number.
11. according to any one variable band-pass filter of claim 1-10, wherein, described at least one that goes up loop and following loop comprises a plurality of resonators that are coupled.
12. according to the variable band-pass filter of claim 11, wherein, at least one of described each loop comprises a plurality of resonators that are coupled with cascade system, so that many signal path are arranged between the terminal resonator.
13. according to the variable band-pass filter of claim 12, wherein, the described resonator of at least some of described at least one loop is coupled in cross-linked step configuration mode.
14., wherein, also comprise: the intersection coupling connection at least one diagonal angle of the resonator on the adjacent cross-linked ladder rungs with at least some resonators of cross-couplings step configuration according to the variable band-pass filter of claim 13.
15. any one variable band-pass filter according to claim 1-14 also comprises the disresonance input circuit node, this node is coupled to the terminal resonator in one of described loop.
16. according to the variable band-pass filter of claim 15, also comprise the group delay equalizing network, described group delay equalizing network also be coupling in input circuit node and with terminal resonator that this node is connected between.
17. according to the variable band-pass filter of claim 15 or 16, also comprise the output circuit node, described output circuit node is coupled to the terminal resonator in another loop.
18. according to the variable band-pass filter of claim 17, also comprise the group delay equalizing network, described group delay equalizing network be connected described output circuit node and with terminal resonator that this node is connected between.
19. aforesaid in fact variable band-pass filter.
20. in fact as above described with reference to the accompanying drawings variable band-pass filter.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0718275A GB2452934B (en) | 2007-09-19 | 2007-09-19 | A tuneable bandpass filter |
| US11/858,024 | 2007-09-19 | ||
| GB0718275.1 | 2007-09-19 | ||
| US11/858,024 US7915977B2 (en) | 2007-09-19 | 2007-09-19 | Tuneable bandpass filter |
| PCT/GB2008/003082 WO2009037425A1 (en) | 2007-09-19 | 2008-09-11 | A tuneable bandpass filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101803108A true CN101803108A (en) | 2010-08-11 |
Family
ID=40304614
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200880108005A Pending CN101803108A (en) | 2007-09-19 | 2008-09-11 | A tuneable bandpass filter |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP2191533A1 (en) |
| CN (1) | CN101803108A (en) |
| WO (1) | WO2009037425A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110364790A (en) * | 2019-07-05 | 2019-10-22 | 京信通信技术(广州)有限公司 | Filter and its multi-zero realize module |
| CN110783671A (en) * | 2019-11-13 | 2020-02-11 | 电子科技大学 | Reconfigurable band-pass filter |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6046658A (en) * | 1998-09-15 | 2000-04-04 | Hughes Electronics Corporation | Microwave filter having cascaded subfilters with preset electrical responses |
| US6337610B1 (en) * | 1999-11-22 | 2002-01-08 | Comsat Corporation | Asymmetric response bandpass filter having resonators with minimum couplings |
| CN1422465A (en) * | 2000-04-06 | 2003-06-04 | 马科尼通讯有限公司 | Wavelength division multiplex (WDM) singnal monitor |
| US20040056737A1 (en) * | 2002-07-29 | 2004-03-25 | Alcatel | Canonical general response bandpass microwave filter |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5390741A (en) * | 1977-01-21 | 1978-08-09 | Nec Corp | Band pass filter |
| JP3610861B2 (en) * | 2000-01-31 | 2005-01-19 | 三菱電機株式会社 | Low pass filter |
| WO2002099969A2 (en) * | 2001-06-05 | 2002-12-12 | Vitesse Semiconductor Corporation | Negative resistance oscillator with overtone and level control |
-
2008
- 2008-09-11 CN CN200880108005A patent/CN101803108A/en active Pending
- 2008-09-11 WO PCT/GB2008/003082 patent/WO2009037425A1/en active Application Filing
- 2008-09-11 EP EP08806241A patent/EP2191533A1/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6046658A (en) * | 1998-09-15 | 2000-04-04 | Hughes Electronics Corporation | Microwave filter having cascaded subfilters with preset electrical responses |
| US6337610B1 (en) * | 1999-11-22 | 2002-01-08 | Comsat Corporation | Asymmetric response bandpass filter having resonators with minimum couplings |
| CN1422465A (en) * | 2000-04-06 | 2003-06-04 | 马科尼通讯有限公司 | Wavelength division multiplex (WDM) singnal monitor |
| US20040056737A1 (en) * | 2002-07-29 | 2004-03-25 | Alcatel | Canonical general response bandpass microwave filter |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110364790A (en) * | 2019-07-05 | 2019-10-22 | 京信通信技术(广州)有限公司 | Filter and its multi-zero realize module |
| WO2021003836A1 (en) * | 2019-07-05 | 2021-01-14 | 京信通信技术(广州)有限公司 | Filter and multi-zero-point implementation module thereof |
| CN110783671A (en) * | 2019-11-13 | 2020-02-11 | 电子科技大学 | Reconfigurable band-pass filter |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2009037425A1 (en) | 2009-03-26 |
| EP2191533A1 (en) | 2010-06-02 |
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Application publication date: 20100811 |