CN115412043B - Symmetrical lumped parameter low-pass filter for improving far-end rejection performance - Google Patents
Symmetrical lumped parameter low-pass filter for improving far-end rejection performance Download PDFInfo
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- CN115412043B CN115412043B CN202211341927.2A CN202211341927A CN115412043B CN 115412043 B CN115412043 B CN 115412043B CN 202211341927 A CN202211341927 A CN 202211341927A CN 115412043 B CN115412043 B CN 115412043B
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- pcb pad
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- pad end
- pass filter
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/0115—Frequency selective two-port networks comprising only inductors and capacitors
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/17—Structural details of sub-circuits of frequency selective networks
- H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
Abstract
The invention discloses a symmetrical lumped parameter low-pass filter for improving far-end inhibition performance, which comprises a first PCB pad end, a second PCB pad end, a first PCB pad strip, a second PCB pad strip and N third PCB pad ends, wherein the N third PCB pad ends are arranged between the first PCB pad end and the second PCB pad end and are sequentially connected; the first PCB pad end and the first third PCB pad end, the adjacent third PCB pad ends and the Nth third PCB pad end and the second PCB pad end are connected in a sensing way; the third PCB pad end is connected with the second PCB pad belt in a capacitive mode; the third PCB pad end is connected with the first PCB pad belt in a capacitive mode; first PCB pad area and second PCB pad area all are provided with several ground connection hole. Through the scheme, the invention has the advantages of simple structure, good far-end inhibition performance and the like.
Description
Technical Field
The invention relates to the technical field of microstrip printed boards, in particular to a symmetrical lumped parameter low-pass filter for improving far-end rejection performance.
Background
The low-pass filter is mainly used for a microstrip printed board. At present, the conventional low-pass filter is usually used by combining capacitance and inductance into an N-order, as shown in fig. 1. The conventional LC low-pass filter has poor stop-band rejection performance at frequencies well above the cut-off frequency. The simulation result of the conventional LC low-pass filter is shown in fig. 2, and the far-end 40dB rejection frequency is 7.6GHz (the stop-band bandwidth is about 6 GHz). Since there is a surface wave with a low cutoff frequency in the microstrip line, the surface wave is easily excited when the circuit is discontinuous or the circuit structure is asymmetric, so that high-frequency suppression is deteriorated.
Therefore, it is urgently needed to provide a symmetric lumped-parameter low-pass filter with a simple structure and good far-end rejection performance for improving the far-end rejection performance.
Disclosure of Invention
The invention aims to provide a symmetrical lumped parameter low-pass filter for improving the far-end inhibition performance, which adopts the following technical scheme:
a symmetrical lumped parameter low-pass filter for improving far-end inhibition performance comprises a first PCB pad end, a second PCB pad end, a first PCB pad strip, a second PCB pad strip and N third PCB pad ends, wherein the N third PCB pad ends are arranged between the first PCB pad end and the second PCB pad end and are sequentially connected; the first PCB pad end and the first third PCB pad end, the adjacent third PCB pad ends and the Nth third PCB pad end and the second PCB pad end are connected in a sensing way; the third PCB pad end is connected with the second PCB pad strip in a capacitive mode; the third PCB pad end is connected with the first PCB pad strip in a capacitive mode; the first PCB pad strip and the second PCB pad strip are provided with a plurality of grounding holes; and N is a positive integer greater than or equal to 1.
Further, a first electric field is formed between the third PCB pad end and the first PCB pad strip, and the direction of the first electric field faces the first PCB pad strip; and a second electric field is formed between the third PCB pad end and the second PCB pad strip, and the direction of the second electric field faces the second PCB pad strip.
Furthermore, a plurality of inductors are arranged between the first PCB pad end and the first third PCB pad end, between the adjacent third PCB pad ends, and between the Nth third PCB pad end and the second PCB pad end; a first capacitor is arranged between the first PCB pad strip and any one of the third PCB pad ends; and a second capacitor is arranged between the second PCB pad strip and any third PCB pad end.
Preferably, the inductance parameter is obtained by a synthesis method of a standard microwave lumped parameter low-pass filter, and the value of the inductance parameter is the same as the inductance value of the corresponding position of the obtained synthesis result; the function form required by the comprehensive method is one of Chebyshev, maximum flatness, an elliptic function or a quasi-elliptic function.
Preferably, the first capacitor and the second capacitor have the same parameter and are half of the corresponding capacitance value in the integrated value of the standard microwave lumped parameter low-pass filter; the function form required by the value obtained by the integration is one of Chebyshev, maximum flatness, an elliptic function or a quasi-elliptic function.
Preferably, the value of N is 2.
Preferably, the grounding holes are arranged on the first PCB land strip and the second PCB land strip at equal intervals.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention skillfully adopts a full-symmetric circuit and layout, and can effectively increase the far-end inhibition performance of high-frequency signals.
(2) The invention uses a coplanar waveguide circuit to destroy the propagation of surface waves in the filter; splitting a capacitor in a low-pass filter prototype into two capacitors with identical values; multiplexing the symmetry characteristics of the coplanar waveguide and the filter prototype; continuity is realized on a physical structure by using symmetry, discontinuity of coplanar ground is effectively reduced, and excitation of a higher-order mode is effectively avoided; the discontinuity of the electric field is reduced by utilizing the characteristic that the charge and discharge directions of the capacitor are the same as the distribution direction of the electric field of the coplanar waveguide, and the excitation of a higher mode is effectively avoided.
In conclusion, the microstrip printed circuit board has the advantages of simple structure, good far-end inhibition performance and the like, and has high practical value and popularization value in the technical field of microstrip printed circuit boards.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of protection, and it is obvious for those skilled in the art that other related drawings can be obtained according to these drawings without inventive efforts.
Fig. 1 is a schematic diagram of a structure of an LC filter in the prior art.
Fig. 2 is a diagram of a simulation test of an LC filter in the prior art.
FIG. 3 is a schematic view of the present invention.
FIG. 4 is a diagram of a simulation test of the present invention.
In the drawings, the names of the parts corresponding to the reference numerals are as follows:
1. a first PCB pad end; 2. a second PCB pad end; 3. a third PCB pad end; 4. a fourth PCB pad end; 5. a first PCB land strip; 6. a second PCB land strip; 7. and a ground hole.
Detailed Description
To further clarify the objects, technical solutions and advantages of the present application, the present invention will be further described with reference to the accompanying drawings and examples, and embodiments of the present invention include, but are not limited to, the following examples. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Examples
As shown in fig. 3, the present embodiment provides a symmetric lumped-parameter low-pass filter for improving the far-end rejection performance. First, the terms "first", "second", and the like in the present embodiment are used only for distinguishing the same kind of components, and are not to be construed as specifically limiting the scope of protection.
In this embodiment, the symmetric lumped-parameter low-pass filter includes a first PCB pad end 1, a second PCB pad end 2, a first PCB pad strip 5 and a second PCB pad strip 6, two third PCB pad ends 3 disposed between the first PCB pad end 1 and the second PCB pad end 2 and sequentially connected to each other, an inductor L1 disposed between the first PCB pad end 1 and the first third PCB pad end 3, an inductor L2 disposed between the adjacent third PCB pad ends 3, an inductor L3 disposed between the second third PCB pad end 3 and the second PCB pad end 2, a capacitor C11 disposed between the first third PCB pad end 3 and the first PCB pad strip 5, a capacitor C13 disposed between the first third PCB pad end 3 and the second PCB pad strip 6, a capacitor C12 disposed between the second third PCB pad end 3 and the first PCB pad strip 5, and a capacitor C14 disposed between the second third PCB pad end 3 and the second PCB pad strip 6. Wherein, a plurality of grounding holes 7 are uniformly arranged on the first PCB pad strip 5 and the second PCB pad strip 6. The grounding hole 7 is connected to the ground. The capacitor C11 and the capacitor C13 have the same parameters, and the capacitor C12 and the capacitor C14 have the same parameters.
In addition, a first electric field is formed between the third PCB land end 3 and the first PCB land strip 5, and the first electric field direction is toward the first PCB land strip 5. A second electric field is formed between the third PCB land end 3 and the second PCB land strip 6 with the second electric field direction towards the second PCB land strip 6. Wherein E in fig. 3 represents an electric field.
In this embodiment, a simulation test of a symmetric lumped-parameter low-pass filter is performed, as shown in fig. 4, it can be seen from the figure that the 40dB out-of-band far-end rejection is 9.3GHz (the stop band bandwidth is about 7.7 GHz), and the out-of-band rejection is improved by (7.7-6)/6 ≈ 28% compared with the conventional microstrip LC filter.
In conclusion, the planar LC filter effectively inhibits the higher-order mode in the planar LC filter, has outstanding substantive characteristics and obvious progress compared with the prior art, and has very high practical value and popularization value in the technical field of microstrip printed boards.
The above-mentioned embodiments are only preferred embodiments of the present invention, and do not limit the scope of the present invention, but all the modifications made by the principles of the present invention and the non-inventive efforts based on the above-mentioned embodiments shall fall within the scope of the present invention.
Claims (3)
1. A symmetrical lumped parameter low-pass filter for improving far-end inhibition performance is characterized by comprising a first PCB pad end (1), a second PCB pad end (2), a first PCB pad strip (5), a second PCB pad strip (6) and N third PCB pad ends (3) which are arranged between the first PCB pad end (1) and the second PCB pad end (2) and are sequentially connected; inductive connection is adopted between the first PCB pad end (1) and the first third PCB pad end (3), between the adjacent third PCB pad ends (3), and between the Nth third PCB pad end (3) and the second PCB pad end (2); the third PCB pad end (3) and the second PCB pad strip (6) are in capacitive connection; the third PCB pad end (3) is connected with the first PCB pad strip (5) in a capacitive mode; the first PCB pad strip (5) and the second PCB pad strip (6) are provided with a plurality of grounding holes (7); n is a positive integer greater than or equal to 1;
a plurality of inductors are arranged between the first PCB pad end (1) and the first third PCB pad end (3), between the adjacent third PCB pad ends (3), and between the Nth third PCB pad end (3) and the second PCB pad end (2); a first capacitor is arranged between the first PCB pad strip (5) and any one third PCB pad end (3); a second capacitor is arranged between the second PCB pad strip (6) and any third PCB pad end (3);
the parameters of the inductor are obtained by adopting a comprehensive method of a standard microwave lumped parameter low-pass filter, and the value of the parameters is the same as the inductance value of the corresponding position of the obtained comprehensive result; the function form required by the comprehensive method is one of Chebyshev, maximum flatness, an elliptic function or a quasi-elliptic function;
the first capacitor and the second capacitor have the same parameters and are half of corresponding capacitance values in the integrated value of the standard microwave lumped parameter low-pass filter; the function form required by the value obtained by the synthesis is one of Chebyshev, maximum flatness, an elliptic function or a quasi-elliptic function;
the grounding holes (7) are distributed on the first PCB pad strip (5) and the second PCB pad strip (6) at equal intervals.
2. A symmetric lumped-parameter low-pass filter with improved far-end rejection performance according to claim 1, wherein a first electric field is formed between the third PCB pad end (3) and the first PCB pad strip (5), and the first electric field is directed towards the first PCB pad strip (5); and a second electric field is formed between the third PCB pad end (3) and the second PCB pad strip (6), and the direction of the second electric field faces the second PCB pad strip (6).
3. The symmetric lumped-parameter low-pass filter with improved far-end rejection performance as claimed in claim 1, wherein N is 2.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211341927.2A CN115412043B (en) | 2022-10-31 | 2022-10-31 | Symmetrical lumped parameter low-pass filter for improving far-end rejection performance |
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| CN202211341927.2A CN115412043B (en) | 2022-10-31 | 2022-10-31 | Symmetrical lumped parameter low-pass filter for improving far-end rejection performance |
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| CN115412043B true CN115412043B (en) | 2023-01-24 |
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| TW200824182A (en) * | 2006-07-12 | 2008-06-01 | Yfy Rfid Technologies Company Ltd | Discontinuous transmission line structure |
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| CN104362421B (en) * | 2014-11-06 | 2017-01-25 | 电子科技大学 | Single-substrate integrated terahertz front end |
| JP6314861B2 (en) * | 2015-01-29 | 2018-04-25 | 株式会社村田製作所 | Electronic components |
| RU2601200C2 (en) * | 2015-03-27 | 2016-10-27 | Открытое акционерное общество "Омский научно-исследовательский институт приборостроения" (ОАО "ОНИИП") | Harmonic filter for short-wave transmitter |
| CN110600846A (en) * | 2019-08-30 | 2019-12-20 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Ultra-wideband band-pass filter with transmission zero |
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