A filter and a communication system

Abstract

The utility model embodiment relates to the field of wireless communication technology, and discloses a filter and a communication system, wherein the filter includes an input end, a first microstrip line, a parallel line component, a first topological structure, a second topological structure, a second microstrip line, and an output end, wherein one end of the first microstrip line is electrically connected to the input end; one end of the parallel line component is electrically connected to the other end of the first microstrip line; one end of the first topological structure is electrically connected to the other end of the parallel line component; one end of the second topological structure is electrically connected to one end of the parallel line component; one end of the second microstrip line is electrically connected to the other end of the parallel line component; and the other end of the second microstrip line is electrically connected to the output end. In the above manner, the utility model embodiment can achieve a dual-passband effect, which is conducive to expanding the use range of the filter.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of wireless communication, and in particular to a filter and a communication system. Background Art

[0002] Filters play an important role in wireless communications. They are used to filter interference signals, remove noise, and select signals of a specific frequency. Currently, most filters are single-passband filters, which can only select signals of a specific frequency, limiting the scope of use of the filters. Utility Model Content

[0003] The main technical problem solved by the embodiments of the utility model is to provide a filter and a communication system, which can achieve a dual-passband effect and help expand the application range of the filter.

[0004] In order to solve the above technical problems, a technical solution adopted in an embodiment of the utility model is: providing a filter, including an input end, a first microstrip line, a parallel line component, a first topological structure, a second topological structure, a second microstrip line and an output end, one end of the first microstrip line is electrically connected to the input end; one end of the parallel line component is electrically connected to the other end of the first microstrip line; one end of the first topological structure is electrically connected to the other end of the parallel line component; one end of the second topological structure is electrically connected to one end of the parallel line component; one end of the second microstrip line is electrically connected to the other end of the parallel line component; the other end of the second microstrip line is electrically connected to the output end.

[0005] In some embodiments, the parallel line assembly includes a first transmission line and a second transmission line, an end of the first microstrip line away from the input end is electrically connected to an end of the first transmission line, an end of the first topology structure is electrically connected to an end of the first transmission line away from the input end, an end of the second topology structure is electrically connected to an end of the second transmission line close to the input end, and one end of the second microstrip line is electrically connected to an end of the second transmission line away from the input end.

[0006] In some embodiments, the first transmission line and the second transmission line are parallel to each other.

[0007] In some embodiments, the first topology structure includes a third microstrip line and a first open branch, one end of the third microstrip line is electrically connected to an end of the first transmission line away from the input end, and one end of the first open branch is electrically connected to the other end of the third microstrip line.

[0008] In some embodiments, the third microstrip line is perpendicular to the first transmission line.

[0009] In some embodiments, the first open-circuit stub is parallel to the first transmission line.

[0010] In some embodiments, the second topology structure includes a fourth microstrip line and a second open branch, one end of the fourth microstrip line is electrically connected to an end of the second transmission line close to the input end, and one end of the second open branch is electrically connected to the other end of the fourth microstrip line.

[0011] In some embodiments, the fourth microstrip line is perpendicular to the second transmission line.

[0012] In some embodiments, the second open-circuit stub is parallel to the second transmission line.

[0013] In order to solve the above technical problems, another technical solution adopted by the embodiment of the utility model is: to provide a communication system, including a substrate and the above filter, wherein the filter is arranged on the surface of the substrate.

[0014] The beneficial effects of the embodiments of the utility model are as follows: different from the prior art, in the embodiments of the utility model, by electrically connecting one end of the first microstrip line to the input end, electrically connecting one end of the parallel line assembly to the other end of the first microstrip line, electrically connecting one end of the first topology structure to the other end of the parallel line assembly, electrically connecting one end of the second topology structure to one end of the parallel line assembly, electrically connecting one end of the second microstrip line to the other end of the parallel line assembly, and electrically connecting the other end of the second microstrip line to the output end, the filter can form two passbands, which is beneficial to expanding the use range of the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the utility model or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0016] Figure 1 It is a schematic diagram of the topological structure of the filter provided in the embodiment of the utility model;

[0017] Figure 2 It is a schematic diagram of the topological structure of the odd-mode form of the filter provided in the embodiment of the utility model;

[0018] Figure 3 It is a schematic diagram of the topological structure of the even-mode form of the filter provided in the embodiment of the utility model;

[0019] Figure 4 It is a schematic diagram of experimental results of the filter provided in the embodiment of the utility model. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the utility model, the utility model is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not used to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0022] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] See also Figure 1 The filter 100 includes: an input terminal 1, a first microstrip line 2, a parallel line component 3, a first topological structure 4, a second topological structure 5, a second microstrip line 6 and an output terminal 7. The input terminal 1 is used to receive an input signal, and the output terminal 7 is used to output a signal. One end of the first microstrip line 2 is electrically connected to the input terminal 1, and one end of the parallel line component 3 is electrically connected to the other end of the first microstrip line 2. One end of the first topological structure 4 is electrically connected to the other end of the parallel line component 3, and one end of the second topological structure 5 is electrically connected to one end of the parallel line component 3, and the first topological structure 4 and the second topological structure 5 are respectively located on both sides of the parallel line component 3. One end of the second microstrip line 6 is electrically connected to the other end of the parallel line component 3, and the other end of the second microstrip line 6 is electrically connected to the output terminal 7.

[0024] For the parallel line component 3 above, see Figure 1The parallel line component 3 includes a first transmission line 31 and a second transmission line 32, the first transmission line 31 and the second transmission line 32 are spaced from each other, and the first transmission line 31 and the second transmission line 32 are parallel to each other. An end of the first microstrip line 2 away from the input end 1 is electrically connected to an end of the first transmission line 31 close to the input end 1, and an end of the first topological structure 4 is electrically connected to an end of the first transmission line 31 away from the input end 1. An end of the second topological structure 5 is electrically connected to an end of the second transmission line 32 close to the input end 1, and an end of the second microstrip line 6 is electrically connected to an end of the second transmission line 32 away from the input end 1.

[0025] For the first topology structure 4 mentioned above, please refer to Figure 1 The first topological structure 4 includes a third microstrip line 41 and a first open branch 42, one end of the third microstrip line 41 is electrically connected to the end of the first transmission line 31 away from the input end 1, one end of the first open branch 42 is electrically connected to the other end of the third microstrip line 41, and the other end of the first open branch 42 is suspended. It is worth noting that the "suspended" mentioned in this application means that there is no other structure or component that is electrically connected to it, and it can be considered as suspended.

[0026] In some embodiments, the third microstrip line 41 is perpendicular to the first transmission line 31 .

[0027] In some embodiments, the first open branch 42 is parallel to the first transmission line 31 , that is, the first open branch 42 is perpendicular to the third microstrip line 41 , thereby reducing the size of the first topology structure 4 in the first direction X, which is parallel to the third microstrip line 41 .

[0028] For the second topology structure 5 mentioned above, please refer to Figure 1 The second topology structure 5 includes a fourth microstrip line 51 and a second open branch 52, one end of the fourth microstrip line 51 is electrically connected to an end of the second transmission line 32 close to the input end 1, one end of the second open branch 52 is electrically connected to the other end of the fourth microstrip line 51, and the other end of the second open branch 52 is suspended.

[0029] In some embodiments, the fourth microstrip line 51 is perpendicular to the second transmission line 32 .

[0030] In some embodiments, the second open branch 52 is parallel to the second transmission line 32 , that is, the second open branch 52 is perpendicular to the second transmission line 32 . This configuration can reduce the size of the second topological structure 5 in the first direction X.

[0031] In some embodiments, see Figure 1 The filter 100 is centrally symmetrically arranged, and its symmetry center is the center point of the parallel line component 3.

[0032] In some embodiments, the electrical length of the first microstrip line 2 and the electrical length of the second microstrip line 6 are equal.

[0033] In some embodiments, the electrical length of the third microstrip line 41 is equal to the electrical length of the fourth microstrip line 51 .

[0034] In some embodiments, the electrical lengths of the first open stub 42 and the second open stub 52 are equal.

[0035] In some embodiments, the electrical length of the first transmission line 31 and the electrical length of the second transmission line 32 are a quarter wavelength corresponding to the center frequency of the stop band between the two pass bands, wherein, referring to FIG. z2 This is the center frequency of the stopband between the two passbands.

[0036] In some embodiments, the sum of the electrical length of the first microstrip line 2, the electrical length of the second microstrip line 6, and the electrical length of the first short-circuit branch is the center frequency f of the stop band between the two pass bands. z2 The corresponding quarter wavelength.

[0037] In some embodiments, the characteristic impedance of the first microstrip line 2, the characteristic impedance of the second microstrip line 6, the characteristic impedance of the third microstrip line 41, the characteristic impedance of the fourth microstrip line 51, the characteristic impedance of the first open-circuit branch 42, and the characteristic impedance of the second open-circuit branch 52 are all equal. Such a setting can reduce the loss of the signal in the filter 100, which is beneficial to the transmission of the signal in the filter 100.

[0038] In some embodiments, see Figure 1 , the length L1 of the parallel line component 3 is 6.65 mm. The spacing S1 between the first transmission line 31 and the second transmission line 32 is 0.1 mm. The width W1 of the first transmission line 31 is 0.15 mm, and the width of the second transmission line 32 is equal to the width of the first transmission line 31. The length L2 of the first microstrip line 2 is 1.2 mm, and the length of the second microstrip line 6 is equal to the length of the first microstrip line 2. The length L3 of the third microstrip line 41 is 0.85 mm, and the length of the fourth microstrip line 51 is equal to the length of the third microstrip line 41. The length L4 of the first open branch 42 is 4.8 mm, and the length of the second open branch 52 is equal to the length of the first open branch 42. The width W2 of the first open branch 42 is 0.15 mm, and the width of the first microstrip line 2, the width of the second microstrip line 6, the width of the third microstrip line 41, the width of the fourth microstrip line 51, the width of the first open branch 42, and the width of the second open branch 52 are all equal.

[0039] In order to help readers better understand the concept of the present application, the filter of the present application is analyzed below.

[0040] The characteristic impedances of the first microstrip line 2, the second microstrip line 6, the third microstrip line 41, the fourth microstrip line 51, the first open branch 42 and the second open branch 52 are all Z1. The odd-mode characteristic impedance of the parallel line component 3 composed of the first transmission line 31 and the second transmission line 32 is Z oo , the even-mode characteristic impedance is Z oe Since the filter 100 is a centrosymmetric structure as a whole, its transmission poles can be obtained by odd-even mode analysis.

[0041] First, it is assumed that the sum of the electrical length of the third microstrip line 41 and the electrical length of the first short-circuit branch is much greater than the electrical length of the first microstrip line 2. In this case, the odd-mode form of the filter 100 is as follows: Figure 2 As shown, the electrical length of the odd-mode transmission line is a quarter wavelength corresponding to the center frequency of the stop band between the two pass bands, and the characteristic impedance of the odd-mode transmission line is Z oo , when f0 is the center frequency of the stopband between the two passbands, the frequencies corresponding to the two odd-mode transmission poles are:

[0042]

[0043] Therefore, when Y ino = 0, it can be concluded that Figure 2 The topological structure formed in has two odd-mode transmission poles, and the frequencies corresponding to these two odd-mode transmission poles are f op1 and f op2 Among them, Y ino is the odd-mode input impedance.

[0044] In addition, it is assumed that the sum of the electrical length of the third microstrip line 41 and the electrical length of the first short-circuit branch is much greater than the electrical length of the first microstrip line 2. In this case, the even-mode form of the filter 100 is as follows: Figure 3 As shown, the electrical length of the even-mode transmission line is a quarter wavelength corresponding to the center frequency of the stop band between the two pass bands, and the characteristic impedance of the even-mode transmission line is Z oe , when f0 is the center frequency of the stopband between the two passbands, the frequencies corresponding to the two even-mode transmission poles are:

[0045]

[0046] Therefore, when Y ine = 0, it can be concluded that Figure 3 The topological structure formed in has two even-mode transmission poles, and the frequencies corresponding to these two even-mode transmission poles are f ep1 and f ep2 Among them, Y ine is the even-mode input impedance.

[0047] For the transmission zero point, it can be obtained by the following formula:

[0048]

[0049] Among them, S 21 is the transmission coefficient of the filter 100. After calculation, it can be concluded that the filter 100 has three transmission zeros, and the frequencies corresponding to the three transmission zeros are f z1 =0, f z2 = f0 and f z3 =2*f0.

[0050] Through the above analysis, it can be known that the filter 100 based on the present application has two odd-mode transmission poles, two even-mode transmission poles and three transmission zeros, and no matter how the odd-mode characteristic impedance Z of the parallel line component 3 is changed oo , even-mode characteristic impedance Z oe and the characteristic impedance Z1 of the first microstrip line 2, the second microstrip line 6, the third microstrip line 41, the fourth microstrip line 51, the first open-circuit branch 42 and the second open-circuit branch 52, and the relative positions of the transmission zero poles, i.e., f z1 <f ep1 <f op1 <f z2 <f op2 <f ep2 <f z3 , will not change, that is, at the first transmission zero point f z1 and the second transmission zero f z2 There are two transmission poles f ep1 and f op1 , at the second transmission zero point f z2 and the third transmission zero f z3 There are two transmission poles f op2 and f ep2 Therefore, the filter 100 of the present application has two passbands, the first passband is located at the first transmission zero point f z1 and the second transmission zero f z2 The second passband is located at the second transmission zero point f z2 and the third transmission zero f z3 There are two transmission poles in the first passband and the second passband. When the signal in the first passband or the second passband is attenuated, another transmission pole can be used to enhance the signal, which is beneficial to ensure that the attenuation of the signal in the passband is kept within a stable range and can reduce the attenuation of the signal in the passband, which is beneficial to ensure the flatness of the signal in the RF device. In addition, the first transmission zero point f z1 and the third transmission zero f z3To ensure high selectivity of the filter, the second transmission zero f z2 This ensures high isolation between the two passbands.

[0051] In order to enable readers to better understand the concept of this application, the following experimental proof is carried out.

[0052] The experimental conditions are as follows: the filter 100 of the present application is set on a circuit board with a dielectric constant of 3.38, a dielectric loss of 0.0022, a thickness of 0.813 mm, and a length and width of 12.8 mm*2.8 mm.

[0053] See also Figure 4 , Figure 4 is a schematic diagram of the experimental results of the filter 100 of the present application, Figure 4 The dashed line represents the reflection coefficient, and the solid line represents the transmission coefficient. Figure 4 It can be seen that there are two passbands with a reflection coefficient less than -10dB, and there is a transmission zero point f between the two passbands. z2 , indicating that the filter 100 of the present application is a dual-passband filter, wherein the frequency range of the first passband is 3.164 GHz to 5.048 GHz, the center frequency of the first passband is 4.106 GHz, the absolute bandwidth of the first passband is 1.884 GHz, the relative bandwidth of the first passband is 45.9%, the frequency range of the second passband is 10.092 GHz to 11.456 GHz, the center frequency of the second passband is 10.774 GHz, the absolute bandwidth of the second passband is 1.364 GHz, and the relative bandwidth of the second passband is 12.7%. In addition, from Figure 4 It can be seen that in the first passband, the maximum insertion loss is 0.48dB, and in the second passband, the maximum insertion loss is 0.63dB, indicating that the filter 100 of the present application has the characteristic of low insertion loss. Figure 4 It can be seen from the figure that the filter 100 of the present application has three transmission zeros, namely f z1 、f z2 and f z3 , the first passband is located at f z1 and f z2 The second passband is located between z2 and f z3 This improves the isolation between the first passband and the second passband and reduces the interference between the first passband and the second passband. In addition, there are two transmission poles in the first passband, namely f ep1 and f op1 , there are also two transmission poles in the second passband, namely f ep2 and f op2 , which can improve the flatness of the signals in the two passbands.

[0054] In the embodiment of the utility model, by electrically connecting one end of the first microstrip line 2 to the input end 1, electrically connecting one end of the parallel line component 3 to the other end of the first microstrip line 2, electrically connecting one end of the first topology structure 4 to the other end of the parallel line component 3, electrically connecting one end of the second topology structure 5 to one end of the parallel line component 3, electrically connecting one end of the second microstrip line 6 to the other end of the parallel line component 3, and electrically connecting the other end of the second microstrip line 6 to the output end 7, the filter 100 can form two passbands, which is beneficial to expanding the scope of use of the filter 100.

[0055] The utility model also provides a communication system embodiment, which is not shown in the figure. The communication system includes a substrate and the above-mentioned filter 100. The filter 100 is arranged on the surface of the substrate. The substrate is used to carry the filter 100. For the specific structure and function of the filter 100, please refer to the above-mentioned embodiment, which will not be repeated here.

[0056] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A filter, characterized in that: include: Input terminal; A first microstrip line, one end of which is electrically connected to the input end; a parallel line component, one end of which is electrically connected to the other end of the first microstrip line; A first topological structure, one end of which is electrically connected to the other end of the parallel line assembly; The second topological structure; One end thereof is electrically connected to one end of the parallel line assembly; a second microstrip line, one end of which is electrically connected to the other end of the parallel line assembly; An output end, the other end of the second microstrip line is electrically connected to the output end.

2. The filter according to claim 1, characterized in that The parallel line assembly includes a first transmission line and a second transmission line, wherein an end of the first microstrip line away from the input end is electrically connected to an end of the first transmission line, an end of the first topology structure is electrically connected to an end of the first transmission line away from the input end, an end of the second topology structure is electrically connected to an end of the second transmission line close to the input end, and an end of the second microstrip line is electrically connected to an end of the second transmission line away from the input end.

3. The filter according to claim 2, characterized in that The first transmission line and the second transmission line are parallel to each other.

4. The filter according to claim 2, characterized in that The first topology structure includes a third microstrip line and a first open branch, one end of the third microstrip line is electrically connected to an end of the first transmission line away from the input end, and one end of the first open branch is electrically connected to the other end of the third microstrip line.

5. The filter according to claim 4, characterized in that The third microstrip line is perpendicular to the first transmission line.

6. The filter according to claim 4, characterized in that The first open branch is parallel to the first transmission line.

7. The filter according to claim 2, characterized in that The second topology structure includes a fourth microstrip line and a second open branch, one end of the fourth microstrip line is electrically connected to an end of the second transmission line close to the input end, and one end of the second open branch is electrically connected to the other end of the fourth microstrip line.

8. The filter according to claim 7, characterized in that The fourth microstrip line is perpendicular to the second transmission line.

9. The filter according to claim 7, characterized in that The second open branch is parallel to the second transmission line.

10. A communication system, characterized in that: The invention comprises a substrate and a filter as claimed in any one of claims 1 to 9, wherein the filter is arranged on a surface of the substrate.

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