WO2018171180A1

WO2018171180A1 - Band-pass filter based on ring resonator

Info

Publication number: WO2018171180A1
Application number: PCT/CN2017/107193
Authority: WO
Inventors: 曲美君; 邓力; 李书芳; 张贯京; 葛新科; 高伟明; 张红治
Original assignee: 深圳市景程信息科技有限公司
Priority date: 2017-03-18
Filing date: 2017-10-21
Publication date: 2018-09-27
Also published as: CN107026303B; CN107026303A

Abstract

The present invention provides a band-pass filter based on a ring resonator. The band-pass filter comprises: a dielectric slab; a ground metal layer provided on the lower surface of the dielectric slab; and an input end, an output end, an input microstrip line, an output microstrip line, a first coupling line, a second coupling line, a ring resonator, a first double-stub open load, a second double-stub open load, a first double-stub impedance matcher, and a second double-stub impedance matcher which are formed on the upper surface of the dielectric slab by means of etching. The band-pass filter is symmetrical about a central axis. According to the present invention, the band-pass filter is symmetrical about a central axis; a ring resonator is formed by the middlemost four microstrip lines, and a double-stub open load is separately loaded at the input end and the output end, to bring a good band-pass matching effect for the band-pass filter within a working band, apply a good inhibitory effect on out-of-band signals, achieve high selectivity on passband signals, introduce less noise, and avoid interference with a radio frequency front end.

Description

Band-pass filter based on ring resonator

[0001] The present invention relates to the field of radio frequency microwave communication technologies, and in particular, to a bandpass filter based on a ring resonator.

Background technique

[0002] As a very important device in the RF front-end, the filter can filter out-of-band noise and improve the sensitivity of the circuit system. A microstrip filter is a device used to separate microwave signals of different frequencies. Its main function is to suppress unwanted signals so that they cannot pass through the filter and only pass the desired signal. In microwave circuit systems, the performance of the filter has a large impact on the performance of the circuit system. Due to the diversity of communication bands in modern communication systems, the selectivity of prior art bandpass filters is often insufficient to meet the diversity of communication bands and affect the performance of the entire communication system.

technical problem

An object of the present invention is to provide a band-pass filter based on a ring resonator, which aims to solve the technical problem of low selectivity of the conventional band-pass filter.

Problem solution

Technical solution

[0004] In order to achieve the above object, the present invention provides a band-pass filter based on a ring resonator, comprising a dielectric plate, a ground metal layer disposed on a lower surface of the dielectric plate, and an input end etched on a surface of the dielectric plate, Output terminal, input microstrip line, output microstrip line, first coupling line, second coupling line, ring resonator, first double branch node load, second double branch node load, first double branch impedance matcher And a second double branch impedance matcher, the band pass filter being bilaterally symmetric about the central axis, wherein:

[0005] one end of the input microstrip line is connected to the input end, and the other end of the input microstrip line is connected to the first double branch impedance matching device;

[0006] one end of the output microstrip line is connected to the output end, and the other end of the output microstrip line is connected to a second double-branch section impedance matcher;

[0007] The first coupling line includes a first coupled microstrip line and a second coupled microstrip line, and one of the first coupled microstrip lines The end is orthogonally connected to one end of the second coupled microstrip line to form an L shape;

[0008] The second coupling line includes a third coupled microstrip line and a fourth coupled microstrip line, and one end of the third coupled microstrip line is orthogonally connected to one end of the fourth coupled microstrip line to form an L shape;

[0009] The ring resonator is a rectangular resonator composed of four resonant microstrip lines, and the ring resonator is disposed between the second coupled microstrip line and the fourth coupled microstrip line;

[0010] The first dual branch node load includes a first load microstrip line and a second load microstrip line, and the second double branch node load includes a third load microstrip line and a fourth load microstrip line, the first load One end of the microstrip line is connected to the input end, the other end of the first load microstrip line is connected to one end of the second load microstrip line, one end of the third load microstrip line is connected to the output end, and the third load microstrip line is connected The other end is connected to one end of the fourth load microstrip line.

[0011] Preferably, the ring resonator comprises a first resonant microstrip line, a second resonant microstrip line, a third resonant microstrip line and a fourth resonant microstrip line, the first resonant microstrip line and the second coupling The spacing between the microstrip lines is equal to the spacing between the third resonant microstrip line and the fourth coupled microstrip line.

[0012] Preferably, a spacing between the input microstrip line and the first coupled microstrip line is equal to a spacing between the output microstrip line and the third coupled microstrip line.

[0013] Preferably, the first double-branch impedance matching device includes a first impedance matching line and a second impedance matching line, and the second double-branch impedance matching device includes a third impedance matching line and a fourth impedance matching line. Wherein: [0014] one end of the first impedance matching line is orthogonally connected with one end of the input microstrip line to form an L shape, and the other end of the first impedance matching line is connected to one end of the second impedance matching line;

[0015] One end of the third impedance matching line is orthogonally connected to one end of the output microstrip line to form an L shape, and the other end of the third impedance matching line is connected to one end of the fourth impedance matching line.

[0016] Preferably, the length of the first line and the third impedance matching lines are 1 ^ ₂ = 23.41 ^^ width are ₂ = 0.27mm W, the second impedance matching line and the fourth line The length is L _{1 =} 21.64 ηιιη. The width is W, = 2.830^1.

[0017] Preferably, the lengths of the first resonant microstrip line and the third resonant microstrip line are both C _u =23.48 mm, and the lengths of the second resonant microstrip line and the fourth resonant microstrip line are both 1^ =23.081^^ The width of the first resonant microstrip line, the second resonant microstrip line, the third resonant microstrip line, and the fourth resonant microstrip line are both W ₅ = 0.25 mm.

[0018] Preferably, the length of the input end and the output end are both L. =15mm, width is W. =1.66mm, The lengths of the input microstrip line and the output microstrip line are both C ₁₂ = 23.8 mm and the width is Cw ₂ = 0.14 mm; the lengths of the first coupled microstrip line and the third coupled microstrip line are both C ₁₂ = 23.8mm, the length of the second coupled microstrip line and the fourth coupled microstrip line are ^, = 23.481^!!, the first coupled microstrip line, the second coupled microstrip line, and the third coupled micro The width of the strip line and the fourth coupled microstrip line is Cw ^ Ο. Πη η^

[0019] Preferably, the lengths of the first load microstrip line and the third load microstrip line are L ₄ = 22.3 mm, and the width is both \¥ ₄ =1.421^^ the second load microstrip line and the fourth load The length of the microstrip line is 1^=22.671^^ and the width is W ₃ =0.915 mm.

[0020] Preferably, a spacing between the first resonant microstrip line and the second coupled microstrip line, and a spacing between the third resonant microstrip line and the fourth coupled microstrip line Cs _{1 =} 0.48ιηιη, The spacing between the input microstrip line and the first coupled microstrip line, and the spacing between the output microstrip line and the third coupled microstrip line are both Cs ₂ =0.465 mm.

[0021] Preferably, the dielectric plate is a PCB having a thickness of 0.762 mm and a relative dielectric constant of 3.66.

Advantageous effects of the invention

Beneficial effect

[0022] Compared with the prior art, the band-pass filter based on the ring resonator of the present invention is bilaterally symmetric about the central axis ab of the band pass filter, wherein the middlemost four microstrip lines can form a ring resonator And loading a double-branch node load at the input terminal P1 and the output terminal P2 respectively, which can provide a good band pass matching effect in the working frequency band of the band pass filter of the present invention. In addition, the band-pass filter based on the ring resonator of the present invention can have a good suppression effect on the out-of-band signal, has high selectivity to the pass band signal, introduces less noise, and avoids interference to the RF front end.

Brief description of the drawing

DRAWINGS

1 is a schematic plan view showing a preferred embodiment of a band pass filter based on a ring resonator of the present invention.

2 is a schematic view showing the structure of a preferred embodiment of a band-pass filter based on a ring resonator of the present invention.

3 is a schematic diagram of S-parameter results of a band-pass filter based on a ring resonator of the present invention simulated by electromagnetic simulation software. [0025] FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be further described in detail with reference to the preferred embodiments thereof. The following examples are illustrative of the invention, and the invention is not limited to the following examples.

Referring to FIG. 1, FIG. 1 is a plan view showing a planar structure of a preferred embodiment of a band-pass filter based on a ring resonator of the present invention. In this embodiment, the band pass filter includes a dielectric plate 1, an input terminal P1 etched on the upper surface of the dielectric plate 1, an output terminal P2, an input microstrip line 11, an output microstrip line 12, and a first coupling line. 13. A second coupling line 14, a ring resonator 15, a first double branch circuit load 16, a second double branch circuit load 17, a first double branch impedance matcher 18, a second double link impedance matcher 19, and A ground metal layer (not shown in Fig. 1) provided on the lower surface of the dielectric plate 1. The dielectric plate 1 is a PCB board, and the specific plate type is Roger RO4350B, wherein the relative dielectric constant is 3.66, and the plate thickness is 0.762 mm. The ground metal layer is a copper-clad metal layer laid on the lower surface of the dielectric plate 1.

[0028] One end of the input microstrip line 11 is connected to the input end P1, and the other end of the input microstrip line 11 is connected to the first double branch impedance matching device 18; one end of the output microstrip line 12 is connected to the output end P2, The other end of the output microstrip line 12 is connected to the second double branch impedance matcher 19. The first dual branch impedance matcher 18 includes a first impedance matching line 181 and a second impedance matching line 182, and the second double branch impedance matching unit 18 includes a third impedance matching line 191 and a fourth impedance matching line 192. One end of the first impedance matching line 181 is orthogonally connected to one end of the input microstrip line 11 to form an L shape, that is, the first impedance matching line 181 and the input microstrip line 11 are perpendicularly connected to each other, and the other end of the first impedance matching line 181 is connected. To one end of the second impedance matching line 182. One end of the third impedance matching line 1 91 is orthogonally connected to one end of the output microstrip line 12 to form an L shape, that is, the third impedance matching line 191 and the output microstrip line 12 are perpendicularly connected to each other, and the other end of the third impedance matching line 191 is connected. Connected to one end of the fourth impedance matching line 192.

[0029] The first coupling line 13 includes a first coupled microstrip line 131 and a second coupled microstrip line 132. One end of the first coupled microstrip line 131 is orthogonally connected to one end of the second coupled microstrip line 132. The L-shape, that is, the first coupled microstrip line 131 and the second coupled microstrip line 132 are perpendicularly connected to each other. The second coupling line 14 includes a third coupled microstrip line 141 and a fourth coupled microstrip line 142. One end of the third coupled microstrip line 141 is orthogonally connected to one end of the fourth coupled microstrip line 142 to form an L shape. The third coupled microstrip line 141 and the fourth coupled microstrip line 142 are perpendicularly connected to each other. The input microstrip line 11 is spaced apart from the first coupled microstrip line 131, and the output microstrip line 12 is spaced apart from the third coupled microstrip line 141. The input microstrip line 11 and the first coupled microstrip line are spaced apart. The spacing between 131 is equal to the spacing between the output microstrip line 12 and the third coupled microstrip line 141. [0030] The ring resonator 15 is disposed between the second coupled microstrip line 132 and the fourth coupled microstrip line 142, and the ring resonator 15 is formed by a rectangle of four resonant microstrip lines, that is, the first resonant microstrip line 151. A rectangular resonator composed of a second resonant microstrip line 152, a third resonant microstrip line 153, and a fourth resonant microstrip line 154. The first resonant microstrip line 151 of the ring resonator 15 is spaced apart from the second coupled microstrip line 132, and the third resonant microstrip line 153 of the ring resonator 15 is spaced apart from the fourth coupled microstrip line 142. The spacing between the first resonant microstrip line 151 and the second coupled microstrip line 132 is equal to the spacing between the third resonant microstrip line 153 and the fourth coupled microstrip line 142.

[0031] The first dual branch circuit load 16 includes a first load microstrip line 161 and a second load microstrip line 162, and the second double branch circuit load 17 includes a third load microstrip line 171 and a fourth load microstrip Line 172. One end of the first load microstrip line 161 is connected to the input terminal P1, and the other end of the first load microstrip line 161 is connected to one end of the second load microstrip line 162. One end of the third load microstrip line 171 is connected to the output terminal P2, and the other end of the third load microstrip line 171 is connected to one end of the fourth load microstrip line 172. The connection of the first load microstrip line 161 to the input terminal P1 does not overlap with the connection of the input microstrip line 11 to the input terminal P1, such that the first coupled microstrip line 131 is spaced from the first load microstrip line 161 There is a gap to prevent mutual interference of signal energy between the two. The junction of the third load microstrip line 171 connected to the output terminal P2 and the output microstrip line 12 connected to the output terminal P1 do not overlap, such that the third coupled microstrip line 141 is spaced from the third load microstrip line 171 There is a gap to prevent mutual interference of signal energy between the two. In this embodiment, a spacing between the first coupled microstrip line 131 and the first load microstrip line 161 is equal to a spacing between the third coupled microstrip line 141 and the third loaded microstrip line 171, the spacing Preferably, it is 2 mm to 5 mm to avoid mutual interference of signal energy between the two.

It should be noted that the band-pass filter based on the ring resonator of the present invention is bilaterally symmetrical with respect to the central axis ab of the band pass filter. The band-resonator-based band-pass filter of the present invention is compared with the existing band-pass filter, wherein the middlemost four microstrip lines can form a ring resonator, and one of the input terminal P1 and the output terminal P2 are respectively loaded. The double-branch node load can provide a good band pass matching effect in the operating band of the band pass filter of the present invention. In addition, the band pass filter designed by the above structure can have a good suppression effect on the out-of-band signal, has high selectivity to the passband signal, introduces less noise, and avoids interference to the RF front end.

Referring to FIG. 2, FIG. 2 is a structural rule of a preferred embodiment of a bandpass filter based on a ring resonator of the present invention. Inch schematic. The invention etches the input terminal PI on the upper surface of the dielectric plate 1, the output terminal P2, the input microstrip line 11, the output microstrip line 12, the first coupling line 13, the second coupling line 14, the ring resonator 15, the first The double branch node load 16, the second double branch node load 17, the first double branch impedance matcher 18 and the second double branch impedance matcher 19 are all metal copper sheets, and the input microstrip line and output micro are involved in the present invention. The strip line, the load microstrip line, the coupled microstrip line, and the resonant microstrip line are all metal strip microstrip lines with a strip structure, just to distinguish each microstrip line by a different name. The present invention is exemplified by an operating band in the range of 1.82 GHz to 2.19 GHz, and the length and width of the structural dimensions of the preferred embodiment of the bandpass filter based on the ring resonator of the present invention are illustrated by way of specific embodiments.

In the embodiment, the lengths of the input end P1 and the output end P2 are both L0=15 mm and the width is W0=1.66 mm. The lengths of the input microstrip line 11 and the output microstrip line 12 are both C12=23.8 mm and the width is Cw2=0.1 4 mm.

[0035] The lengths of the first coupled microstrip line 131 and the third coupled microstrip line 141 are both C12=23.8 mm, and the lengths of the second coupled microstrip line 132 and the fourth coupled microstrip line 142 are both C11=23.48 mm. The width of the first coupled microstrip line 131, the second coupled microstrip line 132, the third coupled microstrip line 141, and the fourth coupled microstrip line 142 is Cwl = 0.17 mm.

[0036] The lengths of the first resonant microstrip line 151 and the third resonant microstrip line 153 of the ring resonator 15 are both C11=23.4 8 mm, and the lengths of the second resonant microstrip line 152 and the fourth resonant microstrip line 154 are both It is L5=23.08mm. The widths of the first resonant microstrip line 151, the second resonant microstrip line 152, the third resonant microstrip line, and the fourth resonant microstrip line 154 are all W5 = 0.25 mm.

[0037] The lengths of the first load microstrip line 161 and the third load microstrip line 171 are both L4=22.3 mm, and the width is W 4=1.42 mm; the second load microstrip line 162 and the fourth load microstrip line The length of 172 is L3=22.67 mm, and the width is W3=0.915 mm.

[0038] The lengths of the first impedance matching line 181 and the third impedance matching line 191 are both L2=23.4 mm and the width is W 2=0.27 mm; the lengths of the second impedance matching line 182 and the fourth impedance matching line 192 are both It is Ll=21.64mm and the width is Wl=2.83mm.

[0039] The spacing between the first resonant microstrip line 151 and the second coupled microstrip line 132, and the spacing between the third resonant microstrip line 153 and the fourth coupled microstrip line 142, Csl = 0.48 mm. The spacing between the input microstrip line 11 and the first coupled microstrip line 13 1 and the spacing between the output microstrip line 12 and the third coupled microstrip line 141 are both Cs2=0.465 mm [0040] It should be noted that the thickness of the metal copper plate disposed on the PCB board is generally um, so the present invention does not refer to the input terminal P1, the output terminal P2, the input microstrip line 11, the output microstrip line 12, and the first The coupling line 13, the second coupling line 14, the ring resonator 15, the first double branch circuit load 16, the second double branch node load 17, the first double branch impedance matcher 18, and the second double link impedance matcher 19 The thickness of the metal copper sheet is limited and does not affect the characteristics of the band-pass filter based on the ring resonator of the present invention.

Referring to FIG. 3, FIG. 3 is a schematic diagram showing the result of simulating the S-parameter of the band-pass filter based on the ring resonator of the present invention through electromagnetic simulation software. In general, bandpass filters allow signals from different frequency bands to enter the system, filtering out-of-band signals or noise. As can be seen from Fig. 3, it can be seen that the reflection coefficient (IS11I) of the band pass filter of the present invention is below -10 dB in the range of 1.82 GHz to 2.19 GHz, indicating that the band pass filter can operate from 1.82 GHz to 2.19 GHz. , can achieve 18.5% relative bandwidth. At 1.1 GHz, the band pass filter of the present invention has a transmission characteristic (IS21I) of -33 dB, and at 2.7 GHz, IS21 冋 reaches -72 dB, so the band pass filter of the present invention has high selectivity. It can be seen that the band-pass filter based on the ring resonator of the invention can have a good suppression effect on the out-of-band signal, has high selectivity to the passband signal, introduces less noise, and avoids interference to the RF front end, so Improve the performance of microwave circuits.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the present invention and the contents of the drawings may be directly or indirectly applied to other related The technical field is equally included in the scope of patent protection of the present invention.

Industrial applicability

Compared with the prior art, the band-pass filter based on the ring resonator of the present invention is bilaterally symmetric with respect to the central axis ab of the band pass filter, wherein the middlemost four microstrip lines can form a ring resonator And loading a double-branch node load at the input terminal P1 and the output terminal P2 respectively, which can provide a good band pass matching effect in the working frequency band of the band pass filter of the present invention. In addition, the band-pass filter based on the ring resonator of the present invention can have a good suppression effect on the out-of-band signal, has high selectivity to the pass band signal, introduces less noise, and avoids interference to the RF front end.

Claims

Claim

[Claim 1] A ring resonator based band pass filter comprising a dielectric plate and a ground metal layer disposed on a lower surface of the dielectric plate, wherein the ring resonator based band pass filter further comprises etching Input on the surface of the dielectric board, output, input microstrip line, output microstrip line, first coupling line, second coupling line, ring resonator, first double branch load, second double branch circuit a load, a first double branch impedance matcher, and a second double branch impedance matcher, the ring resonator based band pass filter being bilaterally symmetric about a central axis of the band pass filter, wherein: one end of the input microstrip line Connected to the input end, the other end of the input microstrip line is connected to the first double branch impedance matching device; one end of the output microstrip line is connected to the output end, and the other end of the output microstrip line is connected to a second double branch impedance matching device; the first coupling line includes a first coupled microstrip line and a second coupled microstrip line, one end of the first coupled microstrip line and the second coupled microstrip line One end is orthogonally connected to form an L shape; the second coupling line includes a third coupled microstrip line and a fourth coupled microstrip line, and one end of the third coupled microstrip line is orthogonally connected with one end of the fourth coupled microstrip line L-shaped; the ring resonator is a rectangular resonator composed of four resonant microstrip lines, the ring resonator is disposed between the second coupled microstrip line and the fourth coupled microstrip line; the first double branch node The load includes a first load microstrip line and a second load microstrip line, and the second dual branch circuit load includes a third load microstrip line and a fourth load microstrip line, and one end of the first load microstrip line is connected to the input end The other end of the first load microstrip line is connected to one end of the second load microstrip line, one end of the third load microstrip line is connected to the output end, and the other end of the third load microstrip line is connected to the fourth load microstrip line One end of the line.

[Claim 2] The ring resonator-based band pass filter according to claim 1, wherein the ring resonator includes a first resonant microstrip line, a second resonant microstrip line, and a third resonant micro The strip line and the fourth resonant microstrip line, the spacing between the first resonant microstrip line and the second coupled microstrip line is equal to the spacing between the third resonant microstrip line and the fourth coupled microstrip line.

[Claim 3] The ring resonator-based band pass filter according to claim 2, wherein a spacing between the input microstrip line and the first coupled microstrip line is equal to the output microstrip line The spacing between the third coupled microstrip line. The ring resonator-based bandpass filter according to claim 3, wherein the first double-branch impedance matching device comprises a first impedance matching line and a second impedance matching line, and the second double-branch impedance The matching device includes a third impedance matching line and a fourth impedance matching line, wherein: one end of the first impedance matching line is orthogonally connected with one end of the input microstrip line to form an L shape, and the other end of the first impedance matching line is connected to One end of the second impedance matching line; one end of the third impedance matching line is orthogonally connected with one end of the output microstrip line to form an L shape, and the other end of the third impedance matching line is connected to one end of the fourth impedance matching line.

The ring resonator-based band pass filter according to claim 4, wherein the first impedance matching line and the third impedance matching line have a length of L ₂ = 23.4 mm and a width of W ₂ = 0.27mm, the lengths of the second impedance matching line and the fourth impedance matching line are both L, =21.64mm, and the width is W, =2.830^1.

The ring resonator-based band pass filter according to claim 5, wherein the lengths of the first resonant microstrip line and the third resonant microstrip line are C n=23.48 mm, and the second resonant micro The lengths of the strip line and the fourth resonant microstrip line are both L ₅ = 23.08 mm, and the widths of the first resonant microstrip line, the second resonant microstrip line, the third resonant microstrip line, and the fourth resonant microstrip line are both W ₅ = 0.25 mm.

The ring resonator-based band pass filter according to claim 6, wherein the input end and the output end have a length L. =15mm, width is W. = 1.66mm, the length of the microstrip input line, the output of the microstrip line are C ₁₂ = 23.8mm, width are 2 = 0.14mm Cw; coupling said first microstrip line and the third microstrip line coupled lengths are C ₁₂ = 23.8mm, and the second coupling microstrip line length of the fourth coupled microstrip lines are C _u = 23.48mm, coupled to said first microstrip line, the second coupling microstrip line, a first The widths of the three coupled microstrip lines and the fourth coupled microstrip line are both Cwl=0.17 mm.

The ring-resonator-based bandpass filter according to claim 7, wherein the lengths of the first load microstrip line and the third load microstrip line are both 1^ ₄ =22.31^^ W ₄ = 1.42 mm, the length of the second load microstrip line and the fourth load microstrip line is L ₃ = 22.67 mm, and the width is \¥ ₃ = 0.915 mm.

A ring resonator-based band pass filter according to claim 8, wherein The spacing between the first resonant microstrip line and the second coupled microstrip line, and the spacing between the third resonant microstrip line and the fourth coupled microstrip line are both Cs _{1 =} 0.48 η ηη, the input micro The spacing between the strip line and the first coupled microstrip line, and the spacing between the output microstrip line and the third coupled microstrip line are both Cs ₂ =0.465 mm.

[Claim 10] The ring resonator-based band pass filter according to any one of claims 1 to 9, wherein the dielectric plate is a plate thickness of 0.762 mm and a relative dielectric constant of 3.66. PC B board.