CN108281738A - Bicyclic mode filter is coupled based on the cascade all-wave length of parallel coupled line head and the tail - Google Patents
Bicyclic mode filter is coupled based on the cascade all-wave length of parallel coupled line head and the tail Download PDFInfo
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- CN108281738A CN108281738A CN201711450248.8A CN201711450248A CN108281738A CN 108281738 A CN108281738 A CN 108281738A CN 201711450248 A CN201711450248 A CN 201711450248A CN 108281738 A CN108281738 A CN 108281738A
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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
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20381—Special shape resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P7/00—Resonators of the waveguide type
- H01P7/08—Strip line resonators
- H01P7/082—Microstripline resonators
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Abstract
The invention discloses one kind coupling bicyclic mode filter based on the cascade all-wave length of parallel coupled line head and the tail, which is made of two cascade toroidal cavity resonators of head and the tail.Two head and the tail cascade coupling rings are formed by two pair of 3/4 guide wavelength parallel coupled line and a pair of 1/4 guide wavelength parallel coupled line, head and the tail grade is associated in the both ends of that intermediate a pair of parallel coupling line to the two pairs of parallel coupled lines in left and right respectively, to ensure that two toroidal cavity resonators are satisfied by all-wave length coupling.The filter construction can theoretically generate 8 transmission zeros outside passband, since input and output load cross-linked form using source, 1 transmission zero can be additionally generated, so actually the filter construction inhibits with 9 transmission zeros of outer generation to effectively realize high stop band.21.2% bandwidth and Wide stop bands may be implemented in whole circuit structure, simple in structure, only single layer structure, small, are easy to and the integrated use of other planar circuits.
Description
Technical field
The invention belongs to microwave and millimeter wave mixing plane integrated circuits, and in particular to one kind being based on parallel coupled line head and the tail grade
The all-wave length of connection couples bicyclic mode filter.
Background technology
In Modem radio and mobile communication system, microwave circuit is same with this towards complicated and integrated development
When, filter plays an extremely important and essential role wherein, since the filter of planar structure can be adopted
It is manufactured with printed circuit technique, and its compact structure, size be small and low cost manufacturing, is more applicable for commercialized answer
With, so the filter of the class formation is favored by extensive researchers.In addition, the filter designed using parallel coupled line structure
Wave device has that structure design is simple, the small and high performance feature of circuit size, so cause the interest of extensive researcher.In recent years
Come, more and more researchers are dedicated to the filter research that highly selective and high stop band inhibits, however, the annular of existing design
Filter construction there are the shortcomings that have：(1) though the inhibition outside band is good, the performance in band is poor, and passband edge declines slow, band
Interior selectivity is poor；(2) passband of filter is relatively narrow；(3) entire circuit structure is complicated, size is big, and design is relatively complicated, and band
Outer inhibition is poor, is not thorough.
Invention content
In view of this, the embodiment of the present invention provides one kind coupling Crossed Circle based on the cascade all-wave length of parallel coupled line head and the tail
Filter, simple in structure and small volume；Improve stopband inhibition.
The embodiment of the present invention provides a kind of based on the bicyclic mode filter of the cascade all-wave length coupling of parallel coupled line head and the tail, packet
It includes：
First port, second port, the first parallel coupled line (3), the second parallel coupled line (4), third parallel coupled line
(5)；
First parallel coupled line (3) includes the first coupled microstrip line and the second coupled microstrip line；
Second parallel coupled line (4) includes third coupled microstrip line and the 4th coupled microstrip line；
The third parallel coupled line (5) includes the 5th coupled microstrip line and the 6th coupled microstrip line；
First coupled microstrip line connects the first port；
6th coupled microstrip line connects the second port；
Second coupled microstrip line forms the first close ring with the third coupled microstrip line；
4th coupled microstrip line forms the second close ring with the 5th coupled microstrip line.
Further, the length of first parallel coupled line and the third parallel coupled line is 3/4 guide wavelength；
The length of second parallel coupled line is 1/4 guide wavelength.
Further, the width of second coupled microstrip line and the 5th coupled microstrip line is coupled less than the third
The width of microstrip line and the 4th coupled microstrip line.
Further, the first port and the second port are located at the same side.
Further, further include：First zigzag Microstrip line, the second zigzag Microstrip line；The first port passes through described
One zigzag Microstrip line is connected with one end of first coupled microstrip line；The second port passes through the second zigzag Microstrip line
It is connected with one end of the third coupled microstrip line.
Further, the filter is bilateral symmetry, and symmetrical center line is in second parallel coupled line
Heart line.
Further, first parallel coupled line is anti-arch；The third parallel coupled line is arch；.
Further, first parallel coupled line is identical with the coupling gap of the third parallel coupled line is
The coupling gap of 0.15mm, second parallel coupled line are 0.42mm.
Further, the dielectric constant of medium substrate is 2.65, and the height of medium substrate is 1mm.
Further, first coupled microstrip line, the second coupled microstrip line, the 5th coupled microstrip line and the 6th coupling are micro-
Width with line is 0.54mm, and the third coupled microstrip line and the 4th coupling microstrip line width are 1.05mm.
The filter that above-described embodiment provides only is made of three sections of parallel coupled lines, bicyclic humorous relative to traditional side coupling
The device that shakes is simple in structure and small volume；All-wave couples double-ring resonance device can be with relative to traditional side coupling double-ring resonance device structure
More transmission zeros are generated, stopband inhibition is substantially increased；By the length, width, the coupling spacing that adjust parallel coupled line
The position of bandwidth and transmission zero can be changed easily.
Description of the drawings
To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment
Attached drawing is briefly introduced, it should be apparent that, drawings in the following description are only some embodiments of the invention, for this
For the those of ordinary skill in field, without having to pay creative labor, it can also be obtained according to these attached drawings
His attached drawing.
Fig. 1 is the vertical view of the filter of the embodiment of the present invention.
Fig. 2 is the ideal circuit model schematic of the filter of the embodiment of the present invention.
Fig. 3 is the ideal circuit frequency response chart of the filter of the embodiment of the present invention.
Fig. 4 (a) is frequency response chart of the filter of the embodiment of the present invention in the case where coefficient of coup k1 changes.
Fig. 4 (b) is frequency response chart of the filter of the embodiment of the present invention in the case where coefficient of coup k2 changes.
Fig. 5 is the simulation curve figure of the filter of the embodiment of the present invention.
Fig. 6 is frequency response chart of the filter of the embodiment of the present invention in the case where input and output coupling length changes.
Fig. 7 is frequency of the filter of embodiment of the present invention in the case of second, the 5th coupled microstrip line change width
Response diagram.
Specific implementation mode
To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing to the present invention make into
It is described in detail to one step, it is clear that the described embodiments are only some of the embodiments of the present invention, rather than whole implementation
Example.Based on the embodiments of the present invention, obtained by those of ordinary skill in the art without making creative efforts
All other embodiment, shall fall within the protection scope of the present invention.
Fig. 1 is provided by one embodiment of the present invention based on the cascade all-wave length coupling Crossed Circle filter of parallel coupled line head and the tail
The structural schematic diagram of wave device.In the present embodiment, filter includes：First parallel coupled line 3, the second parallel coupled line 4, third are flat
Row coupling line 5；The length of first parallel coupled line and third parallel coupled line is 3/4 guide wavelength；Second parallel coupled line
Length be 1/4 guide wavelength.
First parallel coupled line 3 includes the first coupled microstrip line and the second coupled microstrip line；Second parallel coupled line 4 includes
Third coupled microstrip line and the 4th coupled microstrip line；Third parallel coupled line 5 includes that the 5th coupled microstrip line and the 6th coupling are micro-
Band line.Second coupled microstrip line forms the first close ring with third coupled microstrip line；4th coupled microstrip line couples micro- with the 5th
Band line forms the second close ring.The width of second coupled microstrip line and the 5th coupled microstrip line is less than third coupled microstrip line and the
The width of four coupled microstrip lines.First parallel coupled line is anti-arch；Third parallel coupled line is arch.
First port and second port are located at the same side.First coupled microstrip line connects the first port；6th coupling
Microstrip line connects the second port；One end phase that first port passes through the first zigzag Microstrip line and the first coupled microstrip line
Even；Second port is connected by the second zigzag Microstrip line with one end of third coupled microstrip line.
In Fig. 1, three pairs of parallel coupled lines mutually cascade, and form two all-waves altogether and couple close ring, by adjusting parallel coupling
The width of zygonema, coupling gap etc. can be readily adjusted the position of zero to change the coefficient of coup of parallel coupled line.
Entire circuit is bilateral symmetry, and symmetrical center line is the center line of second parallel coupled line, size 38mm*
The dielectric constant of 26.44mm*1mm, medium substrate are 2.65, thickness 1mm.Microstrip line 1 in Fig. 1,2 length is 18mm, wide
Degree is 2.7mm, the first coupled microstrip line that the first parallel coupled line 3 and third parallel coupled line 5 are included, the second coupling microstrip
The width of line, the 5th coupled microstrip line and the 6th coupled microstrip line is 0.54mm, and coupling spacing is 0.15mm, and length is
The width of 78.3mm, third coupled microstrip line and the 4th coupled microstrip line that the second parallel coupled line 4 is included are 1.05mm, coupling
Conjunction spacing is 0.42mm, the equal 25.6mm of length.
Fig. 2 is the ideal circuit figure that the cascade all-wave length of the parallel coupled line head and the tail couples bicyclic mode filter, wherein
θ represents the electrical length of the second parallel coupled line, Z0e2And Z0o2Indicate the odd and even mode characteristic impedance of the second parallel coupled line, first is flat
The electrical length of row coupling line 3 and third parallel coupled line 5 is 3 θ, and odd and even mode characteristic impedance is respectively Z0e1And Z0o1.Using resistance
The method of anti-network matrix analyzes the circuit, we can obtain the voltage and current situation of each port：V2=V5, I2=-I5, V3=
V8, I3=-I8, V6=V9, I6=-I9, V7=V12, I7=-I12And I4=I11=0, [Z]aRepresent 3 He of the first parallel coupled line
The impedance matrix of third parallel coupled line 5, [Z]bIt is defined as the impedance matrix of the first parallel coupled line 2.We can count as a result,
Calculate the impedance matrix of entire ideal circuit is：
Wherein,
According to the relationship of impedance matrix and S parameter, we can obtain transmission coefficient S21Expression formula：
By enabling S21=0, the expression formula that we can obtain 8 transmission zeros is as follows：
ftz1=0 (10)
ftz8=2f0(17) wherein,
Fig. 3 gives the ADS simulation results of ideal circuit model (Fig. 2), which has eight transmission zero outside passband
Point inhibits stopband, is conformed exactly to the calculated results.There are 4 (f in eight transmission zerostz1、ftz3、ftz6、ftz8)
It is fixed, is located at 0,2f0/ 3,4f0/ 3,2f0Position, and four additional transmission zero (ftz2、ftz4、ftz5、ftz7) be with
Characteristic impedance (the Z of three sections of parallel coupled lines0e1、Z0o1、Z0e2、Z0o2) related, the expression formula such as formula (10)-of eight transmission zeros
(20) shown in.Usually, we indicate that the coefficient of coup of one section of coupling line, definition are using k：K=(Z0e-Z0o)/
(Z0e+Z0o), Fig. 4 (a)-(b) describes S respectively21The coupled systemes of simulation result and the first parallel coupled line and third parallel coupled line
Number k1(k1=(Z0e1-Z0o1)/(Z0e1+Z0o1)) and the second parallel coupled line coefficient of coup k2(k2=(Z0e2-Z0o2)/(Z0e2+
Z0o2)) relationship.It can be obtained by solution to formula and ADS simulation results (Fig. 4), ftz2、ftz4、ftz5、ftz7With
Z0e1、Z0o1、Z0e2、Z0o2It is related, i.e., with related k1And k2It is related, so with k1And k2Change, ftz2、ftz4、ftz5、ftz7Meeting
It shifts, theory meets just with ADS analogous diagrams, illustrates that this four transmission zeros are controllable, and ftz1、ftz3、ftz6、ftz8Not with
k1And k2Change and change.The conclusion can be also obtained from formula (10)-(20).It can also be obtained by Fig. 4 (a)-(b), the band of passband
It is wide mainly by the coefficient of coup k of the first parallel coupled line and third parallel coupled line1It determines, k1Bigger, bandwidth is wider；And second
The coefficient of coup k of parallel coupled line2The inhibition amplitude of main controlling transmission zero, k2Smaller, Out-of-band rejection amplitude is higher.Fig. 1 is
The cascade all-wave length of the parallel coupled line head and the tail couples the practical circuit diagram of bicyclic mode filter, is used in input/output terminal
It is the cross-linked form of source-load, can additionally generates 1 transmission zero, so actually the filter construction is outer in band
9 transmission zeros can be generated, is illustrated in figure 5 and bicyclic mode filter is coupled based on the cascade all-wave length of parallel coupled line head and the tail
The filter centre frequency of actual circuit simulation curve figure, design is 2.08GHz.It can be clearly seen that 9 transmission zero in figure
Point, demonstrates our theory, if the filter for designing other centre frequencies also has this conclusion.
In Fig. 6, as preferred embodiment provided by the invention, when the first coupled microstrip line of filter is coupled with the 6th
The electrical length of microstrip line is 3/4 guide wavelength, i.e., when input, output end are the coupling of 3/4ths wavelength, out-of-band transmission
Zero up to 9, effectively increases the Out-of-band rejection ability of filter.And when the first coupled microstrip line and the 6th coupling of filter
The electrical length for closing microstrip line is 1/4 guide wavelength, i.e., when input, output end are quarter-wave coupling, band unofficial biography
Defeated zero will substantially reduce, and the Out-of-band rejection ability of filter is caused significantly to deteriorate.Obvious preferable implementation provided by the invention
Example forms cascade ring using two pair of 3/4 guide wavelength parallel coupled line and a pair of 1/4 guide wavelength parallel coupled line, due to entire
Loop configuration is cascaded to be formed by parallel coupled line, and two rings are satisfied by all-wave coupling, and input/output terminal is negative using source-
Cross-linked form is carried, so some unwanted modes of resonance can be inhibited, generates 9 transmission zeros, greatly
Improve stopband inhibition.
In Fig. 7, the width of the second coupled microstrip line and the 5th coupled microstrip line remains equal, uses W1It indicates.Work as W1It is small
When the width of third coupled microstrip line and the 4th coupled microstrip line, as preferred embodiment provided by the invention, it is preferable that
W1=0.54mm, at centre frequency 2.08GHz, pass band width is about 21.2%, and filter squareness factor is preferable.And work as W1
When more than or equal to the width of third coupled microstrip line and the 4th coupled microstrip line, for example, W1=1.05mm or 1.56mm
When, the bandwidth and squareness factor of filter significantly deteriorate, or even the case where trap occur.Obviously provided by the invention preferable
The first close ring of embodiment pair and the second close ring use the design of stepped impedance formula, improve the pass-band performance of filter, expand
The big bandwidth of filter.
It is that the cascade all-wave length of parallel coupled line head and the tail couples the design method of bicyclic mode filter and specific above
Example design, two pair of 3/4 guide wavelength parallel coupled line and a pair of 1/4 guide wavelength parallel coupled line form cascade ring, due to
Entire loop configuration is cascaded to be formed by parallel coupled line, and two rings are satisfied by all-wave coupling, and input/output terminal using
The cross-linked form of source-load generates 9 transmission zeros, greatly so can inhibit some unwanted modes of resonance
The earth improves stopband inhibition.The three dB bandwidth of entire frequency band is about 21.2%, and the inhibition amplitude of upper stopband, which reaches, to be better than
The inhibition amplitude of 30dB, lower stopband reach better than 20dB, and there is very good stopband to inhibit.And entire operating circuit structure is set
Meter is simple, and practicability is stronger, and it is the circuit simulation curve graph at 2.08GHz that Fig. 5, which show the filter model in centre frequency,
Its circuit as shown in Figure 1, size be 38mm*26.44mm*1mm, it is light-weight.
Finally it should be noted that：The above embodiments are only used to illustrate the technical solution of the present invention., rather than its limitations；To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, it will be understood by those of ordinary skill in the art that：Its according to
So can with technical scheme described in the above embodiments is modified, either to which part or all technical features into
Row equivalent replacement；And these modifications or replacements, various embodiments of the present invention technology that it does not separate the essence of the corresponding technical solution
The range of scheme.
Claims (10)
1. one kind coupling bicyclic mode filter based on the cascade all-wave length of parallel coupled line head and the tail, including：First port, second end
Mouthful, the first parallel coupled line (3), the second parallel coupled line (4), third parallel coupled line (5)；
First parallel coupled line (3) includes the first coupled microstrip line and the second coupled microstrip line；
Second parallel coupled line (4) includes third coupled microstrip line and the 4th coupled microstrip line；
The third parallel coupled line (5) includes the 5th coupled microstrip line and the 6th coupled microstrip line；
First coupled microstrip line connects the first port；
6th coupled microstrip line connects the second port；
It is characterized in that：
Second coupled microstrip line forms the first close ring with the third coupled microstrip line；
4th coupled microstrip line forms the second close ring with the 5th coupled microstrip line.
2. filter according to claim 1, which is characterized in that first parallel coupled line (3) and the third are flat
The length of row coupling line (5) is 3/4 guide wavelength；The length of second parallel coupled line (4) is 1/4 guide wavelength.
3. filter according to claim 1, which is characterized in that second coupled microstrip line and the 5th coupling are micro-
Width with line is less than the width of the third coupled microstrip line and the 4th coupled microstrip line.
4. filter according to claim 2, which is characterized in that the first port and the second port are positioned at same
Side.
5. filter according to claim 4, which is characterized in that further include：First zigzag Microstrip line (1), the second complications
Microstrip line (2)；
The first port is connected by the first zigzag Microstrip line (1) with one end of first coupled microstrip line；
The second port is connected by the second zigzag Microstrip line (2) with one end of the third coupled microstrip line.
6. according to claim 1-5 any one of them filters, which is characterized in that the filter is bilateral symmetry,
Symmetrical center line is the center line of second parallel coupled line (4).
7. filter according to claim 6, which is characterized in that first parallel coupled line (3) is anti-arch；It is described
Third parallel coupled line (5) is arch.
8. filter according to claim 6, which is characterized in that first parallel coupled line (3) and the third are flat
The identical coupling gap of row coupling line (5) is 0.15mm, and the coupling gap of second parallel coupled line (4) is 0.42mm.
9. filter according to claim 6, which is characterized in that the dielectric constant of medium substrate is 2.65, medium substrate
Height be 1mm.
10. filter according to claim 6, which is characterized in that first coupled microstrip line, the second coupling microstrip
The width of line, the 5th coupled microstrip line and the 6th coupled microstrip line is 0.54mm, the third coupled microstrip line and the 4th coupling
Conjunction micro belt line width is 1.05mm.
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Cited By (3)
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| CN111547805A (en) * | 2020-06-12 | 2020-08-18 | 厦门大学深圳研究院 | Efficient water treatment and purification device based on electrospinning nanofiber column and preparation method thereof |
| CN112397866A (en) * | 2020-12-03 | 2021-02-23 | 苏州灿勤通讯技术有限公司 | Ultra-wideband ring coupler |
| CN115954634A (en) * | 2023-03-09 | 2023-04-11 | 四川太赫兹通信有限公司 | Small-frequency-ratio dual-frequency band-pass filter |
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