A topology and wideband bandstop filter

Abstract

The application discloses a kind of topology and wideband band-stop filter, topology, including two first microstrip lines, two second microstrip lines, four third microstrip lines, four first open-circuit branches and four second open-circuit branches;Two first microstrip lines are horizontally placed and connected, and the end of one first microstrip line is connected with the input end of two first open-circuit branches, and the end of another first microstrip line is connected with the output end of another two first open-circuit branches;Two second microstrip lines are vertically placed and connected, and the connection of two second microstrip lines coincides with the connection of two first microstrip lines;The end of each second microstrip line is connected with two third microstrip lines, and the third microstrip line is horizontally placed, and the end of third microstrip line away from second microstrip line is connected with second open-circuit branch;Topology is both left-right symmetric structure, and also upper-lower symmetric structure.The wideband band-stop filter based on the topology has the advantages of miniaturization, high selectivity, simple design process, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of filter, in particular to a topology structure and a wideband band-stop filter. BACKGROUND

[0002] With the rapid development of modern wireless communication technology, the contradiction between limited frequency spectrum resources and increasing information transmission demand is increasingly intense, and various communication systems and communication modes are increasingly close to or even staggered in frequency space, which brings great challenges to the anti-interference ability of each communication system to other systems. In addition, with the increasing integration of devices, miniaturization of microwave systems is the only way in the future. Under this background, the miniaturization and high selectivity of filters have high scientific research and commercial value, attracting the attention of many scholars and engineers.

[0003] Unfortunately, however, compared with band-pass filters, the research results of band-stop filters are very few, and basically have defects such as poor selectivity, non-compact structure, narrow stop band, complex design process, etc., which seriously affect their use in modern wireless communication systems. SUMMARY

[0004] The main purpose of the present application is to propose a new topology structure, aiming to solve the problems of poor selectivity and large volume of existing band-stop filters.

[0005] In order to solve the above technical problems, the technical solution one adopted by the present application is: a topology structure, comprising two first microstrip lines, two second microstrip lines, four third microstrip lines, four first open-circuit stubs and four second open-circuit stubs; the two first microstrip lines are horizontally placed and connected, one end of one of the first microstrip lines is connected to the input end of the two first open-circuit stubs, and the other end of the other first microstrip line is connected to the output end of the other two first open-circuit stubs; the two second microstrip lines are vertically placed and connected, and the connection of the two second microstrip lines coincides with the connection of the two first microstrip lines; one end of each second microstrip line is connected to two third microstrip lines, the third microstrip lines are horizontally placed, and one end of the third microstrip line away from the second microstrip line is connected to the second open-circuit stub; the topology structure is both left-right symmetric and up-down symmetric.

[0006] In order to solve the above technical problems, the technical solution two adopted by the present application is: a wideband band-stop filter, comprising a circuit board, wherein the circuit board is provided with the above topology structure.

[0007] The present application has the advantages that: the topology structure is simple and novel, and can be used to design a wideband band-stop filter. The wideband band-stop filter based on the topology structure has the advantages of miniaturization, high selectivity, few design parameters, simple design process, etc. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0009] Figure 1 This is a structural block diagram of the topology of Embodiment 1 of the present invention;

[0010] Figure 2 This is the circuit layout diagram of the broadband bandstop filter according to Embodiment 1 of the present invention;

[0011] Figure 3 The S-parameter plot of the broadband bandstop filter for the simulation example is shown.

[0012] Explanation of icon numbers:

[0013] 1. First microstrip line;

[0014] 2. Second microstrip line;

[0015] 3. Third microstrip line;

[0016] 4. First branch; 41. First branch; 42. Second branch;

[0017] 5. Second branch opening;

[0018] 6. Input terminal;

[0019] 7. Output terminal. Detailed Implementation

[0020] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present application involve directionality indications such as up, down, left, right, front, back, etc., the directionality indications are only used to explain the relative positional relationship, motion condition, etc. between components in a certain specific posture, as shown in the drawings. If the specific posture changes, the directionality indications will also change accordingly.

[0023] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features.

[0024] In addition, the meaning of "and / or" appearing throughout the text is that it includes three parallel schemes. For example, "and / or" includes the scheme, or the scheme, or the scheme that satisfies both. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0025] In this application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above-mentioned terms in this application can be understood according to the specific circumstances.

[0026] Embodiment one

[0027] Please refer to Figures 1 to 3 Embodiment one of the present application is: Figure 1As shown in the figure, a topology structure includes two first microstrip lines 1, two second microstrip lines 2, four third microstrip lines 3, four first open-circuit stubs 4 and four second open-circuit stubs 5; the two first microstrip lines 1 are horizontally placed and connected, one end of one of the first microstrip lines 1 is connected to the input end 6 of two first open-circuit stubs 4, and one end of the other first microstrip line 1 is connected to the output end 7 of the other two first open-circuit stubs 4; the two second microstrip lines 2 are vertically placed and connected, and the connection positions of the two second microstrip lines 2 coincide with the connection positions of the two first microstrip lines 1; one end of each of the second microstrip lines 2 is connected to two third microstrip lines 3, the third microstrip lines 3 are horizontally placed, and one end of the third microstrip line 3 away from the second microstrip line 2 is connected to the second open-circuit stub 5, and the second open-circuit stub 5 is vertically placed, and the topology structure is both left-right symmetric and up-down symmetric.

[0028] The electrical length of the first open-circuit stub 4 is equal to the electrical length of the first microstrip line, and the electrical length of the first microstrip line is 0.25λ, where λ is the corresponding wavelength at the center frequency of the band-stop filter based on the topology structure. The sum of the electrical length of the second microstrip line 2, the electrical length of the third microstrip line 3 and the electrical length of the second open-circuit stub 5 is 0.5λ.

[0029] In combination with Figure 1 and Figure 2 Optionally, the width of the first microstrip line 1 is smaller than the width of the third microstrip line 3, and the width of the third microstrip line 3 is smaller than the width of the second microstrip line 2.

[0030] The first open-circuit stub 4 has a bending part, and the presence of the bending part can more reasonably arrange the first open-circuit stub 4. In this embodiment, the first open-circuit stub 4 is in the shape of L as a whole, and includes a first stub 41 and a second stub 42, and the length direction of the first stub 41 is consistent with the length direction of the first microstrip line 1.

[0031] The characteristic impedance of the first microstrip line 1 is equal to the characteristic impedance of the first open-circuit stub 4, and the characteristic impedance of the first microstrip line 1 is Z1; the characteristic impedance of the second open-circuit stub 5 is equal to the characteristic impedance of the third microstrip line 3, and the characteristic impedance of the third microstrip line 3 is twice the characteristic impedance of the second microstrip line 2, and the characteristic impedance of the second microstrip line 2 is Z2. Therefore, the band-stop filter based on the topology structure has only two design parameters, i.e., Z1 and Z2. In order to ensure high stopband isolation of the filter and low loss and flatness of the passband, the topology structure parameter setting principle is to make Z1 as large as possible and Z2 as small as possible.

[0032] The embodiment also provides a broadband band-stop filter, comprising a circuit board, wherein the circuit board is provided with the topology structure.

[0033] Simulation example

[0034] A circuit board is obtained, wherein the length of the circuit board is 27.0 mm, the width is 15 mm, the thickness is 0.813 mm, the dielectric constant is 3.38, and the dielectric loss is 0.0022.

[0035] The circuit board is provided with a microstrip structure, wherein the microstrip structure is the topology structure, and the circuit layout diagram of the microstrip structure is as shown in Figure 2 .

[0036] The physical length of the first branch of the first open-circuit stub is denoted as l 1H , l 1H = 8.95 mm.

[0037] The physical length of the second branch of the first open-circuit stub is denoted as l 1V , l 1V = 2.0 mm.

[0038] The physical width of the first open-circuit stub is denoted as w1, w1 = 0.1 mm.

[0039] The physical length of the first microstrip line is denoted as l2, l2 = 10.85 mm.

[0040] The physical width of the first microstrip line is denoted as w2, w2 = 0.1 mm.

[0041] The physical length of the second microstrip line is denoted as l3, l3 = 5.8 mm.

[0042] The physical width of the second microstrip line is denoted as w3, w3 = 0.7 mm.

[0043] The physical length of the third microstrip line is denoted as l4, l4 = 11.35 mm.

[0044] The physical width of the third microstrip line is denoted as w4, w4 = 0.35 mm.

[0045] The physical length of the second open-circuit stub is denoted as l5, l5 = 4.1 mm.

[0046] The physical width of the second open-circuit stub is denoted as w5, w5 = 0.35 mm.

[0047] It should be noted that in the simulation example, the sum of l3, l4 and l5 is less than twice of l2 because in the schematic diagram of the topology, the resonators are connected by points, while in the layout diagram, the resonators are connected by surfaces with certain width. The difference between the point and the surface is one of the reasons for the difference between the theoretical value of the topology and the actual layout design value. In addition, in the topology, the resonators are independent and in different spaces, and there is no coupling phenomenon. However, in the layout, all the resonators are in the same space, and there is a coupling problem. Whether there is coupling is the second reason for the difference between the theoretical value of the topology and the actual layout design value.

[0048] Generally speaking, in the topology, the equal electrical length is specified, and in the actual layout, a small difference exists in the corresponding physical length to ensure the optimal simulation result of the filter. Although the equal relationship in the topology can achieve the basic performance of the filter based on the topology, it is not the optimal filter performance. Generally, the lower the working frequency of the filter is, the smaller the difference between the size parameter in the actual layout and the value predicted by the topology will be.

[0049] Figure 3 The S parameter diagram of the simulation example of the wideband band-stop filter is shown in Fig. 6. Figure 3 It can be seen that the isolation of the wideband band-stop filter is greater than 20 dB in the stop band range of 1.644 GHz to 7.138 GHz, the center frequency of the stop band is 4.391 GHz, the absolute bandwidth is 5.494 GHz, and the relative bandwidth is 125.1%. In addition, there are three transmission zeros in the stop band, which are located at 2.085 GHz, 4.483 GHz and 6.842 GHz. There are two pass bands beside the stop band, and there are five transmission poles in the pass band, which are located at 0, 0.368 GHz, 7.943 GHz, 8.762 GHz and 9.768 GHz. The three transmission zeros and the five transmission poles not only ensure the high isolation characteristics of the stop band and the low insertion loss and flatness of the pass band, but also ensure the high selectivity of the band-stop filter sideband.

[0050] The above is only an optional embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A topology, characterized by: The topology structure comprises two first microstrip lines, two second microstrip lines, four third microstrip lines, four first open-circuit stubs and four second open-circuit stubs; the two first microstrip lines are horizontally placed and connected, one end of one first microstrip line is connected with two first open-circuit stubs, and one end of the other first microstrip line is connected with the other two first open-circuit stubs; the two second microstrip lines are vertically placed and connected, and the connection positions of the two second microstrip lines coincide with the connection positions of the two first microstrip lines; each second microstrip line is connected with two third microstrip lines at one end, the third microstrip lines are horizontally placed, and the second open-circuit stubs are connected with the ends of the third microstrip lines away from the second microstrip lines; the topology structure is both left-right symmetric and up-down symmetric. The characteristic impedance of the first microstrip line is equal to the characteristic impedance of the first open-circuit stub. The characteristic impedance of the second open-circuit stub is equal to the characteristic impedance of the third microstrip line, and the characteristic impedance of the third microstrip line is twice the characteristic impedance of the second microstrip line.

2. The topology of claim 1, wherein: The second open-circuit stub is vertically placed.

3. The topology of claim 1, wherein: The electrical length of the first open-circuit stub is equal to the electrical length of the first microstrip line.

4. The topology of claim 1, wherein: The electrical length of the first microstrip line is 0.25λ, and λ is the corresponding wavelength at the center frequency of the band-stop filter based on the topology structure.

5. The topology of claim 4, wherein: The sum of the electrical length of the second microstrip line, the electrical length of the third microstrip line and the electrical length of the second open-circuit stub is 0.5λ.

6. The topology of claim 1, wherein: The width of the first microstrip line is smaller than the width of the third microstrip line, and the width of the third microstrip line is smaller than the width of the second microstrip line.

7. The topology of claim 1, wherein: The first open-circuit stub has a bending part.

8. A wideband bandstop filter characterized by: The circuit board is provided with the topology structure according to any one of claims 1-7.

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