CN101217210A - A three frequency band filter based on parallel coupled line structure - Google Patents
A three frequency band filter based on parallel coupled line structure Download PDFInfo
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- CN101217210A CN101217210A CNA2008100193456A CN200810019345A CN101217210A CN 101217210 A CN101217210 A CN 101217210A CN A2008100193456 A CNA2008100193456 A CN A2008100193456A CN 200810019345 A CN200810019345 A CN 200810019345A CN 101217210 A CN101217210 A CN 101217210A
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Abstract
A tri-band filter which is based on a parallel coupling line structure relates to a tri-band filter with controllable bandwidth and adjustable center frequency. An input-output stage resonator is composed of a first transmission line (1), a second transmission line (2), a third transmission line (3) and a fourth transmission line (4), which are connected in series, a first parallel coupling structure (5) is connected with the fourth transmission line (4); a middle stage resonator is composed of a sixth transmission line (6), a seventh transmission line (7) and an eighth transmission line (8) in serial, a second parallel coupling structure (9) is connected with the sixth transmission line (6) and the eighth transmission line (8) and is symmetrical with the first parallel coupling structure (5); a contact coupling structure (10) is connected on the second transmission line (2) and the third transmission line (3) of the input-output stage resonator, and an input-output port (11) is arranged on the contact coupling structure (10). The invention can work in the tri-band filter, the design is simple, the processing is convenient and the cost is low.
Description
Technical field
The present invention relates to a kind of band pass filter, relate in particular to a kind of triple-band filter with controlled bandwidth and tunable center frequency.
Background technology
Existing market has produced demand to many band filters to the demand of multi-mode-multi-band communication system.First resonance frequency design that coupled line filter in the past only is absorbed in resonator realizes that multiband need design a plurality of filters respectively, all relatively wastes on expense and space hold.
In order to allow a plurality of frequency bands share same resonator, need to use the higher order resonances frequency of resonator.Traditional uniform impedance resonator only is operated in the first resonance frequency f
0, its higher order resonances fixed-frequency is at 2f
0, 3f
0On.M.Makimoto in 1997, S.Yamashita professor on the 45th phase of IEEE Transactions MicrowaveTheory Techniques roundup step electric impedance resonator (syllogic), this resonator can go to change the higher order resonances frequency by the impedance of adjusting each section transmission line.The step electric impedance resonator successfully is used for the high order harmonic component of rejects trap.
In order to realize the multiband filter, most critical be to design the coupled structure that required coupling coefficient is provided on each frequency range.Common parallel coupled line symmetrically can not provide these coupling coefficients.The present invention proposes and use two groups of asymmetric parallel coupled lines of cascade to realize three coupling coefficients on the frequency band.1975 to constantly there being the scholar to propose to analyze the analytic formula of asymmetric parallel coupled line impedance matrix between nineteen ninety, the article of delivering on the phase at the MTT-23 of IEEE Transactions Microwave Theory Techniques such as V.Tripathi professor in 1975.Based on these analytic formula, it is simple and quick that the design of coupled structure becomes.
Summary of the invention
Technical problem: the present invention proposes a kind of coupled structure that realizes by asymmetric parallel coupled line cascade, widened the excursion of connecting curve, can satisfy filter coupled coefficient requirement.And the five-part form step electric impedance resonator that the present invention uses has satisfied the control requirement to three operating frequencies of filter.
Technical scheme: the triple-band filter based on parallel coupled line structure of the present invention comprises two axially the input and output level resonator and the intergrade resonators between these two axially symmetrical input and output level resonators of symmetry; Wherein, input and output level resonator is made of first transmission line, second transmission line, the 3rd transmission line, the series connection of the 4th transmission line, and the first parallel coupled structure is connected with the 4th transmission line; The intergrade resonator is made of the 6th transmission line, the 7th transmission line and the series connection of the 8th transmission line, and the second parallel coupled structure is connected with the 6th transmission line, the 8th transmission line, and parallel coupled structure symmetry with first; On second transmission line of input and output level resonator and the 3rd transmission line, be connected with the Contact Coupled structure, on the Contact Coupled structure, be provided with input/output port.Described Contact Coupled structure is connected the outside of second transmission line and the 3rd transmission line of input and output level resonator.In the parallel coupled structure with second of the described first parallel coupled structure is to be formed by the first asymmetric parallel coupled line and the second asymmetric parallel coupled line cascade.
Beneficial effect: compared with prior art, the present invention has the following advantages:
1, the present invention can be operated in three tunable frequencies.The resonator of being made up of multistage transmission line and coupled structure has been guaranteed the tuning requirement to the filter operating frequency, and different impedances can obtain three different resonance frequencys with the transmission line combination of phase lengths.
2, the present invention has tunable pass band width.Select to use parallel coupled structure or Contact Coupled structure, can adjust the coupling coefficient of each frequency band, obtain adjustable pass band width and low passband reflection.
3, design process simple and fast of the present invention; Design is comprehensive based on conventional filter, and design process all has the analytic formula support, to the dependency degree reduction of 3 D electromagnetic simulation software.
Description of drawings
Fig. 1 is a structural representation of the present invention.
Fig. 2 is the detail view of parallel coupling unit of the present invention.
Fig. 3 is the admittance phase inverter curve chart of parallel coupling unit of the present invention.
Fig. 4 is scattering parameter emulation of the present invention and measurement result.
Have among the above figure: first transmission line 1, second transmission line 2, the 3rd transmission line 3, the 4th transmission line 4, the first parallel coupled structure 5, the 6th transmission line 6, the 7th transmission line 7, the 8th transmission line 8, the second parallel coupled structure 9, Contact Coupled structure 10, input/output port 11, first asymmetric parallel coupled line 12, the second asymmetric parallel coupled line 13.
Embodiment
Triple-band filter with controlled bandwidth and tunable center frequency of the present invention, first transmission line 1 that comprises input and output level resonator, second transmission line 2, the 3rd transmission line 3, the 4th transmission line 4, and the first parallel coupled structure 5 that is connected the asymmetric parallel coupled line composition between input and output level resonator and the intergrade resonator, the 6th transmission line 6 of intergrade resonator, the 7th transmission line 7 and the 8th transmission line 8, the second parallel coupled structure 9 of intergrade resonator opposite side, be connected the Contact Coupled structure 10 on input and output level resonator second transmission line 2 and the 3rd transmission line 3, on Contact Coupled structure 10, be provided with output port 11.The parallel coupled structure 9 with second of the first parallel coupled structure 5 is to be formed by the first asymmetric parallel coupled line 12 and second asymmetric parallel coupled line 13 symmetrical cascade.
The impedance of input and output level resonator and each transmission line section of intergrade resonator and phase lengths can be used for adjusting the needed resonance frequency of acquisition.Contact Coupled structure 10 presents bending structure, and contact position can move adjusts the grade coupled coefficient of input and output.The parallel coupled structure 9 with second of the first parallel coupled structure 5 can be finished Design of Filter by adjusting the intergrade coupling coefficient of line width, spacing and length acquiring demand.
The 6th transmission line 6 and the 8th transmission line 8 present bending and save filter length.
Fig. 3 has provided parallel coupled structure under the situation of different asymmetric parallel coupled line width ratios, the situation of change of reduced admittance phase inverter curve under normalized frequency, as seen from the figure, the maximum value position of curve can have a bigger distribution, can from 0.4 to 0.6 under the normalized frequency, and the symmetrical parallel line be distributed in 0.5 less than near, this shows that asymmetric parallel coupled line widened obtainable coupling coefficient and distributed.Fig. 4 has provided scattering parameter amplitude (dB) emulation of the present invention and measurement result compares, be respectively the passband that 2GHz, 3.5GHz and 5.8GHz have realized relative bandwidth 6% in centre frequency as can be seen from scheming us, design is based on three rank Chebyshev's original shape Design of Filter, the passband reflected signal that measures is less than-18dB, be better than 1dB at the first and second passband differential losses, be better than 2.5dB at the 3rd passband differential loss.
Claims (3)
1. the triple-band filter based on parallel coupled line structure is characterized in that this filter comprises two axially the input and output level resonator and the intergrade resonators between these two axially symmetrical input and output level resonators of symmetry; Wherein, input and output level resonator is made of first transmission line (1), second transmission line (2), the 3rd transmission line (3), the 4th transmission line (4) series connection, and the first parallel coupled structure (5) is connected with the 4th transmission line (4); The intergrade resonator is made of the 6th transmission line (6), the 7th transmission line (7) and the 8th transmission line (8) series connection, and the second parallel coupled structure (9) is connected with the 6th transmission line (6), the 8th transmission line (8), and parallel coupled structure with first (5) symmetry; On second transmission line (2) of input and output level resonator and the 3rd transmission line (3), be connected with Contact Coupled structure (10), on Contact Coupled structure (10), be provided with input/output port (11).
2. the triple-band filter based on parallel coupled line structure according to claim 1 is characterized in that described Contact Coupled structure (10) is connected the outside of second transmission line (2) and the 3rd transmission line (3) of input and output level resonator.
3. the triple-band filter based on parallel coupled line structure according to claim 1 is characterized in that in the described first parallel coupled structure with second of parallel coupled structure (5) (9) it being to be formed by the first asymmetric parallel coupled line (12) and second asymmetric parallel coupled line (13) cascade.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008100193456A CN101217210B (en) | 2008-01-04 | 2008-01-04 | A three frequency band filter based on parallel coupled line structure |
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| CN2008100193456A CN101217210B (en) | 2008-01-04 | 2008-01-04 | A three frequency band filter based on parallel coupled line structure |
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| CN101217210A true CN101217210A (en) | 2008-07-09 |
| CN101217210B CN101217210B (en) | 2011-06-29 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101901950A (en) * | 2010-07-05 | 2010-12-01 | 南京赛格微电子科技有限公司 | Broadband triple-band filter |
| CN101630766B (en) * | 2009-07-23 | 2012-07-18 | 西安空间无线电技术研究所 | Antiphase coupling elliptic function spiral wave filter |
| CN101699649B (en) * | 2009-10-30 | 2012-09-26 | 华南理工大学 | Plane compact type three-passband filter |
| CN101694899B (en) * | 2009-10-16 | 2012-11-07 | 电子科技大学 | Microstrip bandpass filter with sector open-circuit structure |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1607695A (en) * | 2003-10-16 | 2005-04-20 | 海泰超导通讯科技（天津）有限公司 | Micro band filter with fork-shaped hair pin type structure for microwave communication |
| US7215226B2 (en) * | 2004-05-18 | 2007-05-08 | Via Technologies, Inc. | Skew-symmetrical defected ground structure for parallel-coupled line filters |
-
2008
- 2008-01-04 CN CN2008100193456A patent/CN101217210B/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101630766B (en) * | 2009-07-23 | 2012-07-18 | 西安空间无线电技术研究所 | Antiphase coupling elliptic function spiral wave filter |
| CN101694899B (en) * | 2009-10-16 | 2012-11-07 | 电子科技大学 | Microstrip bandpass filter with sector open-circuit structure |
| CN101699649B (en) * | 2009-10-30 | 2012-09-26 | 华南理工大学 | Plane compact type three-passband filter |
| CN101901950A (en) * | 2010-07-05 | 2010-12-01 | 南京赛格微电子科技有限公司 | Broadband triple-band filter |
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| Publication number | Publication date |
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| CN101217210B (en) | 2011-06-29 |
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