CN103762405B - Double-passband filter - Google Patents
Double-passband filter Download PDFInfo
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- CN103762405B CN103762405B CN201310752031.8A CN201310752031A CN103762405B CN 103762405 B CN103762405 B CN 103762405B CN 201310752031 A CN201310752031 A CN 201310752031A CN 103762405 B CN103762405 B CN 103762405B
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Abstract
The invention discloses a kind of double-passband filter, comprise three rank dual-mode resonators of symmetrical configuration, I/O feeder line, be provided with the first grounding through hole, the second grounding through hole, the medium substrate of the 3rd grounding through hole and metal floor, wherein, three rank dual-mode resonators comprise two first and third rank bimodulus resonant elements, a second-order bimodulus resonant element, and first and third rank bimodulus resonant element is consisted of a closed rectangular ring transmission line cascade one spiral open circuited transmission line a short-circuited transmission line; Second-order bimodulus resonant element adopts 1/2nd wavelength step shape impedance bimodulus resonant elements, / 2nd wavelength step shape impedance bimodulus resonant elements comprise the high-impedance transmission line of two sections of low impedance transmission line and one section helically line structure, first and second rank resonant mode of described three rank dual-mode resonators forms two passbands of filter respectively, this double-passband filter adopts mixing cross coupling structure, can all produce three transmission zeros at each near pass-band.
Description
Technical field
The invention belongs to technical field of micro communication, be specifically related to a kind of double-passband filter.
Background technology
Along with the fast development of wireless communication system, the communication standards such as GSM, CDMA, WCDMA, TD-SCDMA, WIMAX, WLAN start to be used widely.Filter is as the requisite important devices of radio-frequency front-end, its major function is used to crossover frequency, namely blocked the signal of other frequencies by the signal of certain frequency, desirable filter should meet passband undamped and in cut-off frequency decay infinitely great.The quality of design of filter performance directly has influence on the indices of communication system, therefore how to design high selectivity, high-isolation, miniaturized filter seem more and more important.
In the design of traditional double-passband filter, normal employing increases filter order and realizes high isolation between high selectivity and passband, but easily like this causes the problems such as filter circuit configuration is complicated, filter size is too large, cost of manufacture increase.Method at present by increasing transmission zero effectively can improve isolation between the frequency selectivity of double-passband filter and passband, and the technology of common generation transmission zero has cross-couplings, source-load coupling, hybrid electromagnetic coupling etc.Above monotechnics is all adopted from the relevant double-passband filter design reported at present, the double-passband filter of mixing cross-coupling technique is adopted to yet there are no report, mixing cross-coupling technique can well in conjunction with cross-couplings and hybrid electromagnetic coupling technique, more transmission zero can be produced when not increasing double-passband filter size, thus make double-passband filter have isolation between higher selectivity and passband.
Summary of the invention
The object of the invention is to overcome the problems referred to above of the prior art, a kind of double-passband filter that can produce three transmission zeros near pass-band is provided.
For solving the problems of the technologies described above, the present invention by the following technical solutions:
A kind of double-passband filter, comprise three rank dual-mode resonators of symmetrical configuration, I/O feeder line, be provided with the first grounding through hole, second grounding through hole, the medium substrate of the 3rd grounding through hole and metal floor, metal floor is positioned at the lower surface of medium substrate, described three rank dual-mode resonators comprise two first, three rank bimodulus resonant elements, a second-order bimodulus resonant element, described first, three rank bimodulus resonant elements are consisted of a closed rectangular ring transmission line cascade one spiral open circuited transmission line a short-circuited transmission line, two first, three rank bimodulus resonant elements are all positioned at the upper surface of medium substrate, and two first, the short-circuited transmission line of three rank bimodulus resonant elements is all connected with the first grounding through hole, realize two first, the connection of three rank bimodulus resonant elements and ground connection, second-order bimodulus resonant element adopts 1/2nd wavelength step shape impedance bimodulus resonant elements, / 2nd wavelength step shape impedance bimodulus resonant elements comprise the high-impedance transmission line of two sections of low impedance transmission line and one section helically line structure, described two sections of low impedance transmission line embed two group first respectively, by second-order bimodulus resonant element and first in the closed rectangular ring transmission line of three rank resonant elements, three rank resonant elements connect, described high-impedance transmission line is embedded in metal floor, described high-impedance transmission line realizes being connected with low impedance transmission line by the second grounding through hole and the 3rd grounding through hole, first of described three rank dual-mode resonators, second order resonant mode forms two passbands of filter respectively, described I/O feeder line is connected to two first, on the short-circuited transmission line of three rank bimodulus resonant elements.
Further, described I/O feeder line adopts tap structure.
Further, described I/O feeder line is the microstrip line of characteristic impedance 50 ohm.
Compared with prior art, the invention has the beneficial effects as follows:
(1) double-passband filter of the present invention adopts mixing cross coupling structure, three transmission zeros can be all produced at each near pass-band, make filter have high frequency selectivity, the transmission zero be simultaneously positioned between passband makes to have higher isolation characteristic between filter channel;
(2) double-passband filter of the present invention is bilateral structure, and be embedded into by the second resonant element in first and third resonant element and underlying metal ground, whole circuit space utilance is high, and compact conformation, size is less.
Accompanying drawing explanation
Fig. 1 is the structural representation of double-passband filter of the present invention;
Fig. 2 is the frequency response curve of double-passband filter embodiment of the present invention.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
As shown in Figure 1, the double-passband filter in the present embodiment comprises three rank dual-mode resonators 1 of symmetrical configuration, be provided with the first grounding through hole 21, second grounding through hole 22, the medium substrate 2 of the 3rd grounding through hole 23, metal floor 3 and I/O feeder line 4, 5, metal floor 3 is positioned at the lower surface of medium substrate 2, and three rank dual-mode resonators 1 comprise two first, three rank bimodulus resonant elements 11, 12 and a second-order bimodulus resonant element 13, first, three rank bimodulus resonant elements 11 are consisted of, with first a closed rectangular ring transmission line 112 cascade one spiral open circuited transmission line 113 short-circuited transmission line 111, three rank bimodulus resonant elements 11 are the same, and first, three rank bimodulus resonant elements 12 are also consisted of a closed rectangular ring transmission line 122 cascade one spiral open circuited transmission line 123 short-circuited transmission line 121, two first, three rank bimodulus resonant elements 11, 12 upper surfaces being all positioned at medium substrate 2, and two first, three rank bimodulus resonant elements 11, the short-circuited transmission line 111 of 12, 121 are all connected with the first grounding through hole 21, realize two first, three rank bimodulus resonant elements 11, the connection of 12 and ground connection, second-order bimodulus resonant element 12 adopts 1/2nd wavelength step shape impedance bimodulus resonant elements, / 2nd wavelength step shape impedance bimodulus resonant elements comprise two sections of low impedance transmission line 131, 132 and the high-impedance transmission line 133 of one section of helically line structure, wherein, two sections of low impedance transmission line 131, 132 embed two first respectively, three rank resonant elements 11, the closed rectangular ring transmission line 112 of 12, in 122, by second-order bimodulus resonance list 13 and first, three rank resonant elements 11, 12 connect, high-impedance transmission line 133 is embedded in metal floor 3, high-impedance transmission line 133 realizes being connected with low impedance transmission line phase 131 and 132 by the second grounding through hole 22 and the 3rd grounding through hole 23.First and second rank resonant mode of above-mentioned three rank dual-mode resonators 1 forms two passbands of filter respectively.I/O feeder line 4,5 is connected on the short-circuited transmission line 111,121 of two first and third rank bimodulus resonant elements 11,12.
Preferably, the I/O feeder line 4,5 in the present embodiment all adopts characteristic impedance to be 50 ohm and is the microstrip line of tap structure.
The principle of the double-passband filter in the present embodiment is, by introducing electric coupling and magnetic coupling between the closed rectangular ring 112,122 of first and third rank bimodulus resonant element 11,12 and between spiral open circuited transmission line 113,123, introduce magnetic coupling at the first grounding through hole 21 place, form mixing cross-couplings; The electric coupling introduced, magnetic-coupled mutual elimination effect and transmission line harmonic effect can produce three transmission zeros at each near pass-band of double-passband filter, totally six transmission zeros, thus improve frequency selectivity and the interband isolation of filter.
Preferably, the medium substrate 2 in the present embodiment adopts Rogers4350B, thickness 0.508mm, and dielectric constant is 3.66, and the area of filter is 9.20 × 6.10mm
2, corresponding wavelength dimension is 0.09 λ
g× 0.06 λ
g, λ
git is the guide wavelength of the first passband central frequency.The width of I/O feeder line 4,5 is 1.1mm, and length is 3.0mm; The width of the short-circuited transmission line 111,121 of first and third rank bimodulus resonant element 11,12 is 0.2mm, and length is 2.9+4.5mm; The width of closed rectangular ring transmission line 112,122 is 0.2mm, and total length is 15.0mm, and length and the coupling length on the adjacent both sides of closed rectangular ring transmission line 112,122 are 4.5mm, and coupling gap is 0.2mm; The width of helical transmission line 113,123 is 0.2mm, and length is 18.5mm, and coupling length is 3.5mm, and coupling gap is 0.22mm.The width of the low impedance transmission line 131,132 of second-order bimodulus resonant element 12 is 1.4mm, and length is 3.9mm; High-impedance transmission line 133 width is 0.2mm, and length is 30.0mm; The diameter of metal throuth hole 21 is 0.4mm, and the diameter of the second grounding through hole 22, the 3rd grounding through hole 23 is 0.3mm.
Fig. 2 is the frequency response curve of the double-passband filter in the present embodiment, comprises two curve S 11, S21 in figure, and curve S 11 is coverage diagrams of signal port, and curve S 21 is transfer curves of signal.From map analysis, the centre frequency of the first passband is 1.56GHz, and its three dB bandwidth is 23.4%, meet the requirement of gps system, insertion loss is 0.7dB, and return loss is greater than 19.5dB, this passband is in 1.06GHz, 1.82GHz and 2.5GHz place generation three transmission zeros; The centre frequency of the second passband is 3.57GHz, and its three dB bandwidth is 10.3%, meets the requirement of WIMAX system, and insertion loss is 1.1dB, and return loss is greater than 19.2dB, and this passband is in 3.07GHz, 3.86GHz and 4.5GHz place generation three transmission zeros; Meanwhile, be positioned at 1.82GHz, the transmission zero of 2.5GHz and 3.07GHz can improve the isolation between the first passband and the second passband, and visible double-passband filter of the present invention not only has good frequency selectivity, and has higher interband isolation.
Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to so special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combination of not departing from essence of the present invention according to these technology enlightenment disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.
Claims (3)
1. a double-passband filter, it is characterized in that: the three rank dual-mode resonators comprising symmetrical configuration, I/O feeder line, be provided with the first grounding through hole, second grounding through hole, the medium substrate of the 3rd grounding through hole and metal floor, metal floor is positioned at the lower surface of medium substrate, described three rank dual-mode resonators are positioned at the side of described I/O feeder line, described three rank dual-mode resonators comprise two first, three rank bimodulus resonant elements, a second-order bimodulus resonant element, described first, three rank bimodulus resonant elements are consisted of a closed rectangular ring transmission line cascade one spiral open circuited transmission line a short-circuited transmission line, two first, three rank bimodulus resonant elements are all positioned at the upper surface of medium substrate, and two first, the short-circuited transmission line of three rank bimodulus resonant elements is all connected with the first grounding through hole, second-order bimodulus resonant element adopts 1/2nd wavelength step shape impedance bimodulus resonant elements, / 2nd wavelength step shape impedance bimodulus resonant elements comprise the high-impedance transmission line of two sections of low impedance transmission line and one section helically line structure, described two sections of low impedance transmission line embed two group first respectively, by second-order bimodulus resonant element and first in the closed rectangular ring transmission line of three rank bimodulus resonant elements, three rank bimodulus resonant elements connect, described high-impedance transmission line is embedded in metal floor, described high-impedance transmission line realizes being connected with low impedance transmission line by the second grounding through hole and the 3rd grounding through hole, first of described three rank dual-mode resonators, second order resonant mode forms two passbands of filter respectively, described I/O feeder line is connected to two first, on the short-circuited transmission line of three rank bimodulus resonant elements.
2. double-passband filter according to claim 1, is characterized in that: described I/O feeder line adopts tap structure.
3. double-passband filter according to claim 1 and 2, is characterized in that: described I/O feeder line is the microstrip line of characteristic impedance 50 ohm.
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| CN201310752031.8A CN103762405B (en) | 2013-12-31 | 2013-12-31 | Double-passband filter |
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| CN201310752031.8A CN103762405B (en) | 2013-12-31 | 2013-12-31 | Double-passband filter |
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| CN103762405A CN103762405A (en) | 2014-04-30 |
| CN103762405B true CN103762405B (en) | 2015-12-09 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104409810A (en) * | 2014-11-27 | 2015-03-11 | 天津大学 | Micro-strip dual-passband filter based on hybrid electromagnetic coupling |
| CN105514544B (en) * | 2016-01-19 | 2019-04-26 | 厦门大学 | Compact three mode filter of screw type of plane |
| CN106450610A (en) * | 2016-11-10 | 2017-02-22 | 电子科技大学 | A novel dual-passband filter |
| CN107482291B (en) * | 2017-08-16 | 2019-05-24 | 电子科技大学 | A kind of novel double-passband filter |
| CN108232381A (en) * | 2017-12-13 | 2018-06-29 | 南京熊猫电子股份有限公司 | Multi-zero minimizes inserted double-passband filter |
| RU2755294C1 (en) * | 2020-12-28 | 2021-09-14 | Федеральное государственное бюджетное научное учреждение "Федеральный исследовательский центр "Красноярский научный центр Сибирского отделения Российской академии наук" (ФИЦ КНЦ СО РАН, КНЦ СО РАН) | Two-spiral strip resonator |
| CN112993498B (en) * | 2021-02-10 | 2022-05-17 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Suspension strip line ultra-wideband adjustable zero-point band-pass filter |
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| CN103236571A (en) * | 2013-03-28 | 2013-08-07 | 华东交通大学 | Slot-line dual-band bandpass filter |
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| TWI353080B (en) * | 2008-03-25 | 2011-11-21 | Ralink Technology Corp | Second order band-pass filter and wireless apparat |
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| CN103236571A (en) * | 2013-03-28 | 2013-08-07 | 华东交通大学 | Slot-line dual-band bandpass filter |
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| Dual-band bandpass filter using embedded spiral resonator and broadside-coupled meander slot-line;X. Luo 等;《Electronics Letters》;20100805;第46卷(第16期);全文 * |
| Miniaturized Dual-band Bandpass Filter with Wide Stopband Using Stepped Impedance Resonators;Chao Wang 等;《2013 International Workshop on Microwave and Millimeter Wave Circuits and System Technology》;20131025;254-256 * |
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