CN104993195A - Multi-transmission zero balancing filter using coupling feeder lines to perform loading - Google Patents
Multi-transmission zero balancing filter using coupling feeder lines to perform loading Download PDFInfo
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- CN104993195A CN104993195A CN201510277795.5A CN201510277795A CN104993195A CN 104993195 A CN104993195 A CN 104993195A CN 201510277795 A CN201510277795 A CN 201510277795A CN 104993195 A CN104993195 A CN 104993195A
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Abstract
The invention discloses a multi-transmission zero balancing filter using coupling feeder lines to perform loading. The filter comprises symmetrical first and second differential input ports, symmetrical first and second differential output ports and symmetrical first and second branch loading ring resonators. The first and second differential input ports are respectively in cascade connection with first and second impedance conversion lines. The first and second differential output ports are respectively in cascade connection with third and fourth impedance conversion lines. The first impedance conversion line is loaded with a first feeder line. The third impedance conversion line is loaded with a second feeder line. The ring resonator part of the first branch loading ring resonator is coupled with the first and second feeder lines. The second impedance conversion line is loaded with a third feeder line. The fourth impedance conversion line is loaded with a fourth loader line. The ring resonator part of the second branch loading ring resonator is coupled with the third and fourth feeder lines. A first branch is loaded between the first and third feeder line. A second branch and a third branch are loaded between the second and fourth feeder lines. The filter is advantaged by high selectivity, high common-mode rejection and low loss.
Description
Technical field
The present invention relates to the technical field of microwave communication, refer in particular to a kind of many transmission zeros balance filter adopting coupling feed to load.
Background technology
Along with the development of modern communication technology, balance filter is more and more paid close attention to owing to having higher immunity to ambient noise, but possess high common mode inhibition simultaneously, Focal point and difficult point that high selectivity, low-loss balance filter are still research.For suppressing common mode, GDS defect ground, the loading of symmetrical minor matters, introducing transmission path, slot line structure etc. can be adopted to realize.But these methods do not improve the selectivity of differential mode passband.For this reason, some diverse ways are used to introduce transmission zero, as direct minor matters loading, source-load coupling, cascade four stage structure etc., not only increase the complexity of design, also can have an impact to common mode inhibition.On the other hand, high-performance balance filter proposes harsher requirement to differential mode passband differential loss.Some high common mode inhibition structures, if slot line structure is due to self radiation loss, can cause passband differential loss larger.In addition, some high selectivity structures as cascade four stage structure because the increase passband differential loss of exponent number is also bigger than normal.Therefore, research high selectivity, high common mode inhibition, low-loss many transmission zeros balance filter have extremely important theory significance, greatly economic benefit and wide application prospect.
Balance filter proposes for a long time, and the prior art below with regard to high selectivity high common mode inhibition balance filter does an investigation.Wherein the most basic implementation is for representative with a series of minor matters loading structures of Lei Zhu team proposition.Within such as its 2009, deliver the article being entitled as " Highly selective differential-mode wideband bandpassfilter for UWB application " at IEEE Microwave and Wireless ComponentsLetters, as shown in Figure 8, in order to improve the selectivity of differential mode passband, quarter-wave minor matters are replaced with four/three-wavelength minor matters.It not only produces two transmission zeros outward at passband, and common mode stopband too increases two transmission zeros.The advantage of this method is improved the selectivity of differential mode passband, widens common mode inhibition model simultaneously.Shortcoming is that differential mode pass band insertion loss is comparatively large, size is larger.
For realizing miniaturized and high abruptness, what Q X Chu team in 2013 delivered on IEEE Microwave andWireless Components Letters is entitled as in " Differential Wideband BandpassFilter With High-Selectivity and Common-Mode Suppression ", uses coupling minor matters to substitute traditional transmission line minor matters.As shown in Figure 9, coupling minor matters substitute traditional minor matters connecting line and can realize wider passband, and short circuit coupling minor matters can introduce two transmission zeros at passband due to its dual transfer zero characteristic.Then dual path is adopted for common mode inhibition.The advantage of this method design be miniaturized, selectivity is high.Shortcoming is common mode inhibition poor effect, only about 10dB.
Within 2014, W Q Che team is at IET Microwaves, Antennas & Propagation delivers in the article being entitled as " Compact wideband balanced bandpass filter with highcommon-modesuppression based on cascade parallel coupled lines ", propose to adopt parallel coupled line to realize wider differential mode passband and higher common mode inhibition, as shown in Figure 10.For improving the selectivity of passband, the SIR minor matters of the extra cascaded symmetric of input/output port, add the complexity of design.
In order to realize high selectivity and high common mode inhibition simultaneously, step electric impedance resonator cascade four stage structure (SIR-CQ) is often used in the design of balance filter.As shown in figure 11, two two/wavelength SIR resonators to different impedance ratio and electrical length are employed.Differential mode harmonics frequency can be made at 5.5f by regulating impedance ratio
0place, common mode operation is at 3.43f
0place.Because four SIR resonators are CQ arrangement, during differential mode, response determines primarily of coupling path resonator a-b-b-a, and path a-a introduces cross-couplings, can produce two transmission zeros at differential mode.During common mode, response determines primarily of path a-a, and the minor matters of tap place can produce transmission zero, make common mode inhibition arrive 6.176f
0.The advantage of this method design is that size is little, selectivity is high.Shortcoming is larger pass band insertion loss, reaches 3.5dB.
From upper surface analysis, although existing structure can realize high common mode inhibition or high selectivity or loss, possesses high selectivity, difficult point that high common mode inhibition, low-loss many transmission zeros balance filter are still design simultaneously.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, many transmission zeros balance filter that the employing coupling feed of a kind of high selectivity, high common mode inhibition, low differential loss loads is provided.
For achieving the above object, technical scheme provided by the present invention is: a kind of many transmission zeros balance filter adopting coupling feed to load, include the first Differential Input port and the second Differential Input port of specular, the first minor matters of the first difference output port of specular and the second difference output port and specular load toroidal cavity resonator and the second minor matters load toroidal cavity resonator, wherein, described first Differential Input port and the second Differential Input port, first difference output port and the second difference output port, first minor matters load toroidal cavity resonator and the second minor matters load the same symmetry axis of toroidal cavity resonator, described first Differential Input port cascade has the first impedance transformation line, described second Differential Input port cascade has the second impedance transformation line, described first difference output port level is associated with the 3rd impedance transformation line, described second difference output port level is associated with the 4th impedance transformation line, described first impedance transformation line and the distribution of the second impedance transformation line specular, described 3rd impedance transformation line and the distribution of the 4th impedance transformation line specular, and their symmetry axis is perpendicular to the symmetry axis of above-mentioned first Differential Input port and the second Differential Input port, described first impedance transformation line is loaded with the first feeder line, described 3rd impedance transformation line is loaded with the second feeder line, described first minor matters load the toroidal cavity resonator part of toroidal cavity resonator and are positioned at the region that the first feeder line and the second feeder line surround, and be coupled with this first feeder line and the second feeder line respectively, described second impedance transformation line is loaded with the 3rd feeder line, described 4th impedance transformation line is loaded with the 4th feeder line, described second minor matters load the toroidal cavity resonator part of toroidal cavity resonator and are positioned at the region that the 3rd feeder line and the 4th feeder line surround, and be coupled with the 3rd feeder line and the 4th feeder line respectively, the first minor matters are loaded with between described first feeder line and the 3rd feeder line, specular is loaded with and the second minor matters be connected and the 3rd minor matters between described second feeder line and the 4th feeder line, grounded metal via hole was provided with between described second minor matters and the 3rd minor matters, and with above-mentioned first Differential Input port and the same symmetry axis of the second Differential Input port, the loading minor matters part that described first minor matters load toroidal cavity resonator and the second minor matters loading toroidal cavity resonator is positioned at this first minor matters, second minor matters, in the region that 3rd minor matters surround.
The loading minor matters part that described first minor matters load toroidal cavity resonator and the second minor matters loading toroidal cavity resonator forms by two sections of minor matters, T-shaped.
Compared with prior art, tool has the following advantages and beneficial effect in the present invention:
1, compared with existing common mode inhibition implementation method, the coupling feed loading structure that the present invention adopts, can produce multiple transmission zero when common mode.Realize the common mode inhibition of feed end.Can by differential mode and common mode characteristic separately design, design independent, easy, common mode inhibition is significantly improved.
2, compared with existing balance filter high selectivity implementation method, the coupling feed loading structure that the present invention adopts at differential mode passband for producing multiple transmission zero, can improve the selectivity outside differential mode passband band.
3, the scheme loading toroidal cavity resonator based on coupling feed loading structure and minor matters of the present invention's proposition, can form three transmission poles at passband, optionally reduce differential mode pass-band loss in improvement simultaneously.
4, the minor matters that the minor matters that the present invention uses load toroidal cavity resonator adopt two sections of T-type structures, can be produce extra transmission zero at common and different mode passband, obviously improve abruptness and the common mode inhibition effect of differential mode.
5, the balance filter of the present invention's design possesses high selectivity, high common mode inhibition, low-loss advantage simultaneously, and adopt planar structure, cost is low simultaneously, and characteristic is good, easy of integration.
Accompanying drawing explanation
Fig. 1 is the structure chart of many transmission zeros balance filter that employing coupling feed of the present invention loads.
Fig. 2 is medium substrate schematic diagram used in the present invention.
Fig. 3 a is the differential mode equivalent circuit figure of many transmission zeros balance filter that employing coupling feed of the present invention loads.
Fig. 3 b is the common mode equivalent circuit figure of many transmission zeros balance filter that employing coupling feed of the present invention loads.
Fig. 4 is with or without loading minor matters Z
1time differential-mode characteristic curve chart (Z
2=92 Ω, Z
3=44 Ω, Z
oo=85 Ω, Z
oe=185 Ω).
Fig. 5 is different loading minor matters Z
1time differential-mode characteristic curve chart.
Fig. 6 is the response diagram under two kinds of differences realize situation.
Fig. 7 a is the differential mode narrow-band response experimental result picture of the many transmission zeros balance filter adopting coupling feed to load.
Fig. 7 b is the differential mode broadband response experimental result picture of the many transmission zeros balance filter adopting coupling feed to load.
Fig. 7 c is the common-mode response experimental result picture of the many transmission zeros balance filter adopting coupling feed to load.
Fig. 8 is the modified model minor matters line structure wideband balance filter graph architecture of Lei Zhu team in background technology.
Fig. 9 is the coupling minor matters wideband balance filter graph architecture of Q X Chu team in background technology.
Figure 10 is the parallel coupling minor matters constitutional balance filter graph architecture of W Q Che team in background technology.
Figure 11 is the cascade quadravalence balance electric filter structure figure of W Q Che team in background technology.
Embodiment
Below in conjunction with specific embodiment, the invention will be further described.
As shown in Figure 1, many transmission zeros balance filter that the employing coupling feed described in the present embodiment loads, includes the first Differential Input port A of specular
1with the second Differential Input port B
1, the first difference output port A of specular
4with the second difference output port B
4and the first minor matters of specular load toroidal cavity resonator and the second minor matters load toroidal cavity resonator; Wherein, described first Differential Input port A
1with the second Differential Input port B
1, the first difference output port A
4with the second difference output port B
4, the first minor matters load toroidal cavity resonator and the second minor matters and load the same symmetry axis of toroidal cavity resonator, all symmetrical along horizontal line OO '; Described first Differential Input port A
1level is associated with the first impedance transformation line A
2, described second Differential Input port B
1level is associated with the second impedance transformation line B
2, described first difference output port A
4level is associated with the 3rd impedance transformation line A
3, described second difference output port B
4level is associated with the 4th impedance transformation line B
3, described first impedance transformation line A
2with the second impedance transformation line B
2specular distributes, described 3rd impedance transformation line A
3with the 4th impedance transformation line B
3specular distributes, and their symmetry axis is perpendicular to above-mentioned horizontal line OO ', described first impedance transformation line A
2be loaded with the first feeder line, described 3rd impedance transformation line A
3be loaded with the second feeder line, described first minor matters load the toroidal cavity resonator part A of toroidal cavity resonator
9be positioned at the region that the first feeder line and the second feeder line surround, and be coupled with this first feeder line and the second feeder line respectively, be formed with coupling feed A respectively
5, A
6, described second impedance transformation line B
2be loaded with the 3rd feeder line, described 4th impedance transformation line B
3be loaded with the 4th feeder line, described second minor matters load the toroidal cavity resonator part B of toroidal cavity resonator
9be positioned at the region that the 3rd feeder line and the 4th feeder line surround, and be coupled with the 3rd feeder line and the 4th feeder line respectively, be formed with coupling feed B respectively
5, B
6, between described first feeder line and the 3rd feeder line, be loaded with the first minor matters C
1, be loaded with specular between described second feeder line and the 4th feeder line and the second minor matters C be connected
2with the 3rd minor matters C
3, described second minor matters C
2with the 3rd minor matters C
3between be provided with grounded metal via hole C
4, and be symmetry axis with above-mentioned horizontal line OO ', the described C of grounded metal via hole excessively
4be positioned on this horizontal line OO ', the loading minor matters part that described first minor matters load toroidal cavity resonator and the second minor matters loading toroidal cavity resonator is positioned at this first minor matters C
1, the second minor matters C
2, the 3rd minor matters C
3in the region surrounded; Described first minor matters load the loading minor matters part of toroidal cavity resonator by two sections of minor matters A
7, A
8composition, T-shaped, wherein A
7for loading minor matters vertical portion, A
8for loading minor matters horizontal component; Described second minor matters load the loading minor matters part of toroidal cavity resonator by two sections of minor matters B
7, B
8composition, T-shaped, wherein B
7for loading minor matters vertical portion, B
8for loading minor matters horizontal component.
The minor matters A loaded
7impedance be Z
2, the minor matters A of loading
8for 2Z
2, A
7length and half A
8total electrical length of length is θ
0.The minor matters B loaded
7impedance be Z
2, the minor matters B of loading
8for 2Z
2, B
7length and half B
8total electrical length of length is θ
0.Minor matters load toroidal cavity resonator and feeder line coupling unit (A
5, B
5, A
6, B
6) strange/even mode impedance is respectively Z
oo/ Z
oe, electrical length is θ
0.The minor matters C that coupling feed end loads
2and C
3electrical length is θ
0, the minor matters C of loading
1electrical length is 2 θ
0.Impedance transformation line (the A of input, delivery outlet cascade
2, B
2, A
3, B
3) electrical length is θ
0, impedance is Z
3.
Because whole filter is symmetrical along horizontal line OO ', available differential mode and common mode equivalent analysis.During differential mode, horizontal line OO ' is equivalent to an electric wall, is equivalent to short circuit, and its equivalent electric circuit is for shown in Fig. 3 a.It is in fact a singlemode resonance device that the minor matters that this structure adopts load toroidal cavity resonator, but passband is due to coupling feed (A
5, B
5, A
6, B
6) cross-couplings and have three transmission poles.Therefore by controlling the impedance (Z of coupling line
oe, Z
oo) bandwidth of passband can be controlled.The impedance transformation line Z of input, delivery outlet cascade four/wavelength
3ripple level can be improved further.On the other hand, load minor matters and can improve pass-band performance while realizing the equivalence of balance filter differential mode.As shown in Figure 4, when coupling feed does not load short circuit minor matters Z
1time, band is outer only two transmission zeros.And after loading short circuit minor matters, be still three transmission poles in band, but 6 transmission zeros can be produced outside band, greatly improve the abruptness of passband.And it is less to load minor matters impedance, passband selectivity is more precipitous.
In like manner, during common mode excitation, OO ' is equivalent to open circuit, and common mode equivalent circuit as shown in Figure 3 b.Now filter feeder line loads open circuit and short circuit minor matters respectively.As shown in Figure 5, filter just has good common mode inhibition when coupling feed does not load minor matters.As loading minor matters Z
1after, two extra transmission zeros can be increased outside band equally, clearly strengthen the inhibition of common mode stopband.
When physical size realizes, we have employed practical structures as shown in Figure 1, load minor matters (Z by resonator
2,θ
0) be separated into (A
7, A
8) two sections or (B
7, B
8) two sections of compositions, T-shaped.Do like this one obviously advantage be to produce introducing coupling path, produce extra transmission zero.As simulated effect during implementations different when Fig. 6 gives differential mode, wherein situation 1 is θ for directly loading length
0,impedance is Z
2wide minor matters, situation two is for inventing the structure that adopts.Can see that high sideband place creates extra transmission zero, the return loss improving differential mode passband clearly and selectivity when adopting the structure of invention.In like manner, also extra transmission zero can be created at high sideband place during common mode.
The medium substrate that this example adopts, its relative dielectric constant is 2.55, and thickness is 0.8mm, and loss angle tangent is 0.029.As shown in Figure 2, D
1for using the upper strata metal patch of dielectric-slab, D
2for dielectric layer, D
3for dielectric-slab lower floor grounded metal paster, D
4for ground connection via hole.
This example designs and machined a frequency is 2.4GHz, and three dB bandwidth is the arrowband balance filter of 19%.The circuit parameter of filter is respectively: Z
1=110 Ω, Z
2=92 Ω, Z
3=44 Ω, Z
oo=85 Ω, Z
oe=185 Ω, θ
0=θ
1=θ
2=θ
3=90 °, it is of a size of 0.63 λ
g× 0.7 λ
g.Experimental result is as shown in Fig. 7 a, 7b, 7c.During differential mode work, the centre frequency measuring (Electromagnetic Simulation) is 2.407 (2.39) GHz, and 3dB relative bandwidth is 17% (18.7%), and in band, minimum Insertion Loss is 1 (0.3) dB.Record frequency be 0.9,1.98,2.67,2.98,3.685,4.6,5.68,6.55GHz (0.87,1.96,2.64,2.9,3.5,4.53,5.72,6.73GHz) place produces 8 transmission zeros.Measure the Out-of-band rejection that (Electromagnetic Simulation) all reaches 16dB (18dB dB) respectively within the scope of 2.75-6.78GHz.Measure during common mode operation frequency be 1.44,2.33,3.13,4.3,4.93,6.2,7.35GHz place generation 7 transmission zeros, common mode all reaches the suppression level of more than 18.8dB in 0-6.5GHz.Measurement and Electromagnetic Simulation all create a transmission zero at 2.67GHz place common and different mode, are because resonator loads minor matters introduce coupling path generation.Can see that this place makes selectivity improve zero point, improve common mode inhibition level simultaneously.The advantage of this filter is many common and different modes transmission zero, and shows higher selectivity and common mode inhibition.
The examples of implementation of the above are only the preferred embodiment of the present invention, not limit practical range of the present invention with this, therefore the change that all shapes according to the present invention, principle are done, all should be encompassed in protection scope of the present invention.
Claims (2)
1. the many transmission zeros balance filter adopting coupling feed to load, it is characterized in that: the first Differential Input port and the second Differential Input port that include specular, the first minor matters of the first difference output port of specular and the second difference output port and specular load toroidal cavity resonator and the second minor matters load toroidal cavity resonator, wherein, described first Differential Input port and the second Differential Input port, first difference output port and the second difference output port, first minor matters load toroidal cavity resonator and the second minor matters load the same symmetry axis of toroidal cavity resonator, described first Differential Input port cascade has the first impedance transformation line, described second Differential Input port cascade has the second impedance transformation line, described first difference output port level is associated with the 3rd impedance transformation line, described second difference output port level is associated with the 4th impedance transformation line, described first impedance transformation line and the distribution of the second impedance transformation line specular, described 3rd impedance transformation line and the distribution of the 4th impedance transformation line specular, and their symmetry axis is perpendicular to the symmetry axis of above-mentioned first Differential Input port and the second Differential Input port, described first impedance transformation line is loaded with the first feeder line, described 3rd impedance transformation line is loaded with the second feeder line, described first minor matters load the toroidal cavity resonator part of toroidal cavity resonator and are positioned at the region that the first feeder line and the second feeder line surround, and be coupled with this first feeder line and the second feeder line respectively, described second impedance transformation line is loaded with the 3rd feeder line, described 4th impedance transformation line is loaded with the 4th feeder line, described second minor matters load the toroidal cavity resonator part of toroidal cavity resonator and are positioned at the region that the 3rd feeder line and the 4th feeder line surround, and be coupled with the 3rd feeder line and the 4th feeder line respectively, the first minor matters are loaded with between described first feeder line and the 3rd feeder line, specular is loaded with and the second minor matters be connected and the 3rd minor matters between described second feeder line and the 4th feeder line, grounded metal via hole was provided with between described second minor matters and the 3rd minor matters, and with above-mentioned first Differential Input port and the same symmetry axis of the second Differential Input port, the loading minor matters part that described first minor matters load toroidal cavity resonator and the second minor matters loading toroidal cavity resonator is positioned at this first minor matters, second minor matters, in the region that 3rd minor matters surround.
2. a kind of many transmission zeros balance filter adopting coupling feed to load according to claim 1, it is characterized in that: the loading minor matters part that described first minor matters load toroidal cavity resonator and the second minor matters loading toroidal cavity resonator forms by two sections of minor matters, T-shaped.
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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 |
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|---|---|---|---|---|
| TW201342704A (en) * | 2012-04-13 | 2013-10-16 | Univ Chienkuo Technology | Balanced type common mode signal suppression dual frequency bandpass filter designed by T type and lambda/2 stepp impedance resonator (SIR) |
| CN203760599U (en) * | 2014-03-28 | 2014-08-06 | 南京航空航天大学 | Compact type ultra wide band double-band-notch balance band-pass filter |
| CN204651445U (en) * | 2015-05-26 | 2015-09-16 | 华南理工大学 | A kind of many transmission zeros balance filter adopting coupling feed to load |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW201342704A (en) * | 2012-04-13 | 2013-10-16 | Univ Chienkuo Technology | Balanced type common mode signal suppression dual frequency bandpass filter designed by T type and lambda/2 stepp impedance resonator (SIR) |
| CN203760599U (en) * | 2014-03-28 | 2014-08-06 | 南京航空航天大学 | Compact type ultra wide band double-band-notch balance band-pass filter |
| CN204651445U (en) * | 2015-05-26 | 2015-09-16 | 华南理工大学 | A kind of many transmission zeros balance filter adopting coupling feed to load |
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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