CN103985927A - High common-mode rejection dual-mode broad band balance microstrip filter - Google Patents
High common-mode rejection dual-mode broad band balance microstrip filter Download PDFInfo
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- CN103985927A CN103985927A CN201410194020.7A CN201410194020A CN103985927A CN 103985927 A CN103985927 A CN 103985927A CN 201410194020 A CN201410194020 A CN 201410194020A CN 103985927 A CN103985927 A CN 103985927A
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Abstract
The invention discloses a high common-mode rejection dual-mode broad band balance microstrip filter. A microstrip line structure is adopted for the filter and formed on a dielectric substrate. The mictrostrip balance filter comprises a first filter body and a second filter body which are the same in structure and symmetrical with each other, wherein the first filter body comprises a terminal short circuit and a first resonator with first short circuit branches loaded in the middle, the second filter body comprises a terminal short circuit and a second resonator with second short circuit branches loaded in the middle, and a terminal of the first resonator and a terminal of the second resonator are connected on the plane of symmetry. Two parallel coupled microstrip lines are adopted as a feeder line of the first filter body and a feeder line of the second filter body respectively, and source-load coupling is enhanced by adding a microstrip line resonator at the position of approach between the open circuit terminal of the first filter body and the open circuit terminal of the second filter body. The balance filter has the advantages that the structure is simple and high common-mode rejection is achieved in a passband.
Description
Technical field
The present invention relates to wireless communication technology field, relate in particular to a kind of high common mode inhibition dual mode wideband balance microstrip filter.
Background technology
In modern wireless communication systems, balancing device has received increasing concern, because balancing device can effectively suppress the noise of ambient noise and internal system.Balance filter, as the requisite device of wireless communication system, has obtained research widely in recent years.Balance filter has filter action under difference mode signal excitation, and can effectively suppress the noise of environment and internal system generation, thereby is widely used in modern wireless communications circuits.Common-mode signal can reduce its signal to noise ratio, so in balancing circuitry design, strengthen as far as possible the inhibition level to common-mode signal.
Existing balance filter design is mainly for narrowband systems, and this is because be difficult to accomplish to suppress common-mode signal in very wide frequency band, and balance filter often has very complicated structure.
Summary of the invention
Technical problem to be solved by this invention is the defect for background technology, and a kind of simple in structure, dual mode wideband balance microstrip filter with high common mode inhibition characteristic is provided.
The present invention is for solving the problems of the technologies described above by the following technical solutions:
A high common mode inhibition dual mode wideband balance microstrip filter, comprises the first filter and the second filter that structure is identical, symmetrical;
Described the first filter comprises the first feed line module and the first dual-mode resonator, two equal short circuits of terminal of described the first dual-mode resonator symmetry, and described the first feed line module and the coupling of the first dual-mode resonator;
Described the second filter comprises the second feed line module and the second dual-mode resonator, two equal short circuits of terminal of described the second dual-mode resonator symmetry, and described the second feed line module and the coupling of the second dual-mode resonator;
Symmetrically and be connected on the plane of symmetry, described the first feed line module and the second feed line module are symmetrical for described the first dual-mode resonator and the second dual-mode resonator.
As the further prioritization scheme of a kind of high common mode inhibition dual mode wideband balance microstrip filter of the present invention, described the first feed line module comprises the first feeder line, the second feeder line, first micro-band minor matters, second micro-band minor matters and the 3rd resonator, and described the first dual-mode resonator comprises the first short circuit minor matters and the first resonator;
Described the first short circuit minor matters are carried in the centre position of described the first resonator;
Described the first resonator is U-shaped, and two equal short circuits of terminal;
One end of described the first feeder line and described first micro-vertical being connected of band minor matters, one end of described the second feeder line and described second micro-vertical being connected of band minor matters, the other end of the other end of described the first feeder line and described the second feeder line input/output end port that partners;
Described first micro-with minor matters, second micro-with minor matters respectively with the base coupling of U type the first resonator;
Described first micro-band minor matters and second micro-band minor matters form source-load coupling at symmetry axis, the micro-band minor matters of described the 3rd resonator respectively with the first, second micro-band minor matters coupling;
Described the second feed line module comprises the 3rd feeder line, the 4th feeder line, the 3rd micro-band minor matters, the 4th micro-band minor matters and the 4th resonator, and described the second dual-mode resonator comprises the second short circuit minor matters and the second resonator;
Described the second short circuit minor matters are carried in the centre position of described the second resonator;
Described the second resonator is U font, and two equal short circuits of terminal;
One end of described the 3rd feeder line and described the 3rd micro-vertical being connected of band minor matters, one end of described the 4th feeder line and described the 4th micro-vertical being connected of band minor matters, the other end of the other end of described the 3rd feeder line and described the 4th feeder line input/output end port that partners;
Described the 3rd micro-with minor matters, the 4th micro-U type base with minor matters respectively with the second resonator coupling;
Described the 3rd micro-band minor matters and the 4th micro-band minor matters form source-load coupling at symmetry axis, the micro-band minor matters of described the 4th resonator the respectively with three and the 4th micro-band minor matters coupling;
Described the first feeder line and the 3rd feeder line are symmetrical, and the second feeder line and the 4th feeder line are symmetrical;
Described first micro-band minor matters and the 3rd micro-band minor matters are symmetrical, and second micro-band minor matters and the 4th micro-band minor matters are symmetrical;
Described the first resonator and the second resonator are symmetrical and on the plane of symmetry, connect into " mouth " word structure, and described the 3rd resonator and the 4th resonator are symmetrical;
Described the first short circuit minor matters and the second short circuit minor matters are symmetrical.
In the present invention, wideband balance microstrip filter is under the excitation of difference mode signal, and the terminal of the first resonator and the second resonator is short circuit, and first and second resonator is 1/2nd wave resonator, and it is equivalent to a single-ended broadband filter; Under the excitation of common-mode signal, the terminal of the first resonator and the second resonator is open circuit, first and second resonator is a wave resonator, its resonance frequency is away from the difference mode signal passband of expectation, in the band of difference mode signal, common-mode signal almost can not be propagated, and has so just reached the effect of high common mode inhibition.
The present invention adopts above technical scheme compared with prior art, has following technique effect:
Circuit structure is simple, has very high common mode inhibition characteristic in difference mode signal, and band connection frequency selectivity is high.
Accompanying drawing explanation
Fig. 1 is the micro-printed circuit board (PCB) tangent plane schematic diagram with balance filter of the present invention;
Fig. 2 is the micro-structural representation with balance filter of the present invention;
Fig. 3 is that the present invention is micro-with the equivalent circuit diagram under the excitation of balance filter difference mode signal;
Fig. 4 is the micro-parity mode equivalent electric circuit with the lower dual-mode resonator of balance filter difference mode signal excitation of the present invention;
Fig. 5 is that the present invention is micro-with the equivalent circuit diagram under the excitation of balance filter common-mode signal;
Fig. 6 is the micro-parity mode equivalent electric circuit with the lower dual-mode resonator of balance filter common-mode signal excitation of the present invention;
Fig. 7 is the micro-scattering parameter simulate and test result with balance filter of the present invention;
Fig. 8 is the micro-group delay test result with balance filter of the present invention.
In figure: A1, the first feeder line; A2, the second feeder line; A3, first micro-band minor matters; A4, second micro-band minor matters; A5, the first resonator; A6, the first short circuit minor matters; A7, the 3rd resonator; B1, the 3rd feeder line; B2, the 4th feeder line; B3, the 3rd micro-band minor matters; B4, the 4th micro-band minor matters; B5, the second resonator; B6, the second short circuit minor matters; B7, the 4th resonator; S1, medium substrate; S2, upper strata metal; S3, lower metal; P
in1, input port; P
in2, input port; P
out1, input port; P
out2, output port.
Embodiment
Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
In the present invention, input and output port all adopts sub-miniature A connector welding, so that access is tested or is connected with other circuit.
Fig. 1 is medium substrate of the present invention, and its relative dielectric constant is 2.2, and thickness is 0.508mm, and loss angle tangent is 0.0009.Can certainly select the dielectric-slab of other specifications.In the upper and lower surface of dielectric substrate S1, be coated with respectively metal level S2 and lower metal layer S3, wherein double-passband filter of the present invention is formed at metal level S2, and lower metal layer S3 is as ground plane.
As shown in Figure 2, the invention discloses a kind of high common mode inhibition dual mode wideband balance microstrip filter, it is formed at medium substrate, comprises the first filter and the second filter.
The first filter comprises the first feeder line A1, the second feeder line A2, first micro-with minor matters A3, second micro-the first resonator A5 that has loaded the first short circuit minor matters A6 with minor matters A4, the 3rd resonator A7 and centre position, the first resonator A5 is U-shaped, and two equal short circuits of terminal, first micro-with minor matters A3 with second micro-with minor matters A4 respectively with vertical being connected of one end of the first feeder line A1 and the second feeder line A2, the other end of the first feeder line A1 and the second feeder line A2 is as the input/output end port (P of filter
in1/ P
out1); First is micro-with minor matters A3, second micro-U type base with minor matters A4 respectively with the first resonator A5 coupling, first micro-band minor matters A3 and second micro-band minor matters A4 are at close place's formation source-load coupling, the 3rd resonator A7 is positioned at below, source-load coupling region, adds close coupling.
The second filter comprises the 3rd feeder line B1, the 4th feeder line B2, the 3rd micro-with minor matters B3, the 4th micro-the second resonator B5 that has loaded the second short circuit minor matters B6 with minor matters B4, the 4th resonator B7 and centre position, the second resonator B5 is U-shaped, and two equal short circuits of terminal, the 3rd micro-with minor matters B3 with the 4th micro-with minor matters B4 respectively with vertical being connected of one end of the 3rd feeder line B1 and the 4th feeder line B2, the other end of the 3rd feeder line B1 and the 4th feeder line B2 is as the input/output end port (P of filter
in2/ P
out2), the 3rd is micro-with minor matters B3, the 4th micro-U type base with minor matters B4 respectively with the second resonator B5 coupling, the 3rd micro-band minor matters B3 and the 4th micro-band minor matters B4 are at close place's formation source-load coupling, and the 4th resonator is positioned at the top in source-load coupling region, adds close coupling.
The circuit structure of the first filter represents with AX, and the circuit structure of the second filter represents with BX, and the first filter is identical with the second filter construction and symmetrical, is embodied in the symmetrical configuration that structure that label is AX and label are BX; The first short circuit minor matters A6 loads on the centre position of the first resonator A5, form the dual-mode resonator of symmetrical configuration, the cancellation effect of its parity mode on main path can produce a transmission zero at passband lower limb, two terminals of the first resonator A5 are short circuit, and its length is about 1/2nd of passband central frequency corresponding wavelength; In like manner in the second short circuit minor matters and the second resonator.
As shown in Figure 3, the equivalent circuit structure of a kind of high common mode inhibition dual mode wideband balance microstrip filter of the present invention under difference mode signal excitation, now the first resonator and the second resonator are short circuit in connection, so just be equivalent to a single-ended filter, take the first filter as example explanation without loss of generality./ 2nd wave resonator that now the first resonator A5 is terminal short circuit, intermediate position has loaded the first short circuit minor matters A6, and its parity mode equivalent electric circuit as shown in Figure 4, has two resonance frequencys in passband, be strange mould resonance frequency and even mould resonance frequency, formed dual mode wideband filter.
As shown in Figure 5, the equivalent circuit structure of a kind of high common mode inhibition dual mode wideband balance microstrip filter of the present invention under common-mode signal excitation, still take the first filter as example explanation, without loss of generality.Now two terminals of the first resonator A5 on the plane of symmetry are opened a way, and the first resonator A5 is the resonator of a wavelength, and its resonance frequency is away from the difference mode signal passband of expectation, and its parity mode equivalent electric circuit as shown in Figure 6.
As shown in Figure 7, scattering parameter emulation and the measured result of a kind of high common mode inhibition dual mode wideband balance microstrip filter of the present invention.S wherein
dd11represent the return loss under difference mode signal excitation, S
dd21for the transmission coefficient under difference mode signal excitation, S
cc21for the transmission coefficient under common-mode signal excitation.Described balance microstrip filter centre frequency is 4.3GHz, and its 3dB relative bandwidth is 28%, and emulation and measured result coincide good as we can see from the figure.In difference mode signal passband common-mode signal all-below 40dB, there is very high common mode inhibition effect.
Fig. 8 is the group delay test result of described wideband balance microstrip filter.Group delay is to describe broadband or ultra-wide band filter for the parameter of the lag characteristic of signal.As can be seen from the figure, in difference mode signal passband, group delay changes in the interval of 1.0ns at 0.7ns, fluctuates very little, and group delay has very smooth characteristic.
The above is only the preferred embodiment of the present invention, it should be pointed out that for those skilled in the art, can also make some improvement under the premise without departing from the principles of the invention, and these improvement also should be considered as protection scope of the present invention.
Claims (2)
1. a high common mode inhibition dual mode wideband balance microstrip filter, is characterized in that, comprises the first filter and the second filter that structure is identical, symmetrical;
Described the first filter comprises the first feed line module and the first dual-mode resonator, two equal short circuits of terminal of described the first dual-mode resonator symmetry, and described the first feed line module and the coupling of the first dual-mode resonator;
Described the second filter comprises the second feed line module and the second dual-mode resonator, two equal short circuits of terminal of described the second dual-mode resonator symmetry, and described the second feed line module and the coupling of the second dual-mode resonator;
Symmetrically and be connected on the plane of symmetry, described the first feed line module and the second feed line module are symmetrical for described the first dual-mode resonator and the second dual-mode resonator.
2. high common mode inhibition dual mode wideband balance microstrip filter according to claim 1, it is characterized in that, described the first feed line module comprises the first feeder line, the second feeder line, first micro-band minor matters, second micro-band minor matters and the 3rd resonator, and described the first dual-mode resonator comprises the first short circuit minor matters and the first resonator;
Described the first short circuit minor matters are carried in the centre position of described the first resonator;
Described the first resonator is U-shaped, and two equal short circuits of terminal;
One end of described the first feeder line and described first micro-vertical being connected of band minor matters, one end of described the second feeder line and described second micro-vertical being connected of band minor matters, the other end of the other end of described the first feeder line and described the second feeder line input/output end port that partners;
Described first micro-with minor matters, second micro-with minor matters respectively with the base coupling of U type the first resonator;
Described first micro-band minor matters and second micro-band minor matters form source-load coupling at symmetry axis, the micro-band minor matters of described the 3rd resonator respectively with the first, second micro-band minor matters coupling;
Described the second feed line module comprises the 3rd feeder line, the 4th feeder line, the 3rd micro-band minor matters, the 4th micro-band minor matters and the 4th resonator, and described the second dual-mode resonator comprises the second short circuit minor matters and the second resonator;
Described the second short circuit minor matters are carried in the centre position of described the second resonator;
Described the second resonator is U font, and two equal short circuits of terminal;
One end of described the 3rd feeder line and described the 3rd micro-vertical being connected of band minor matters, one end of described the 4th feeder line and described the 4th micro-vertical being connected of band minor matters, the other end of the other end of described the 3rd feeder line and described the 4th feeder line input/output end port that partners;
Described the 3rd micro-with minor matters, the 4th micro-U type base with minor matters respectively with the second resonator coupling;
Described the 3rd micro-band minor matters and the 4th micro-band minor matters form source-load coupling at symmetry axis, the micro-band minor matters of described the 4th resonator the respectively with three and the 4th micro-band minor matters coupling;
Described the first feeder line and the 3rd feeder line are symmetrical, and the second feeder line and the 4th feeder line are symmetrical;
Described first micro-band minor matters and the 3rd micro-band minor matters are symmetrical, and second micro-band minor matters and the 4th micro-band minor matters are symmetrical;
Described the first resonator and the second resonator are symmetrical and on the plane of symmetry, connect into " mouth " word structure, and described the 3rd resonator and the 4th resonator are symmetrical;
Described the first short circuit minor matters and the second short circuit minor matters are symmetrical.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410194020.7A CN103985927B (en) | 2014-05-09 | 2014-05-09 | A kind of high common mode inhibition dual mode wideband balance microstrip filter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410194020.7A CN103985927B (en) | 2014-05-09 | 2014-05-09 | A kind of high common mode inhibition dual mode wideband balance microstrip filter |
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| Publication Number | Publication Date |
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| CN103985927A true CN103985927A (en) | 2014-08-13 |
| CN103985927B CN103985927B (en) | 2016-01-20 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107887676A (en) * | 2017-10-26 | 2018-04-06 | 上海海事大学 | One kind miniaturization balance double-passband filter |
Citations (3)
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| CN102522616A (en) * | 2012-01-03 | 2012-06-27 | 西安电子科技大学 | Micro-band dual-mode band-pass filter based on double-end short-circuit resonator |
| CN103367845A (en) * | 2013-06-24 | 2013-10-23 | 南京航空航天大学 | Ultra-wideband micro-strip balance filter |
| CN203883098U (en) * | 2014-05-09 | 2014-10-15 | 南京航空航天大学 | High common mode rejection dual mode broadband balance microstrip filter |
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2014
- 2014-05-09 CN CN201410194020.7A patent/CN103985927B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102522616A (en) * | 2012-01-03 | 2012-06-27 | 西安电子科技大学 | Micro-band dual-mode band-pass filter based on double-end short-circuit resonator |
| CN103367845A (en) * | 2013-06-24 | 2013-10-23 | 南京航空航天大学 | Ultra-wideband micro-strip balance filter |
| CN203883098U (en) * | 2014-05-09 | 2014-10-15 | 南京航空航天大学 | High common mode rejection dual mode broadband balance microstrip filter |
Non-Patent Citations (3)
| Title |
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| HONGWEI DENG 等: "High selectivity and CM suppression microstrip balanced BPF and balanced-to-balanced diplexer", 《JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS》 * |
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| MINHTAN DOAN 等: "A Novel Wideband Bandpass Filter Using Open Stubs Multi-mode Square Ring Resonator", 《THE 2012 INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGIES FOR COMMUNICATIONS(ATC 2012)》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107887676A (en) * | 2017-10-26 | 2018-04-06 | 上海海事大学 | One kind miniaturization balance double-passband filter |
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