Topological structure, wide-passband filter and communication equipment
By designing a topology that includes an input terminal, an output terminal, parallel lines, and stubs, the problem of excessively large size of wide passband filters is solved, and a miniaturized wide passband filter with good signal transmission performance is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2026-03-06
AI Technical Summary
Existing wideband filters are too large, which hinders their use in modern high-speed communication systems.
A topology design is adopted, which includes a combination of input terminals, output terminals, parallel lines, microstrip lines and open/short-circuit stubs, to ensure that there are eight transmission poles, five stopband transmission zeros and one passband transmission zero in the band, forming a notch wave characteristic.
Miniaturization of wide passband filters has been achieved, ensuring flatness in the passband, high selectivity and high isolation in the stopband.
Smart Images
Figure CN223978071U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of topology technology, and in particular to a topology, a wide passband filter, and a communication device. Background Technology
[0002] With the rapid development of modern wireless communication technology, people's demand for broadband communication systems that can achieve high-speed data transmission is increasing, and it has become a key research object for practitioners in related fields. Bandpass filters that can suppress in-band interference and transmit signals at high speed, namely broadband bandpass filters with notch characteristics, have attracted the attention of many scholars and engineers and have been studied in depth.
[0003] In the process of realizing this utility model, the inventors discovered that current wide passband filters, in order to ensure notch characteristics, mostly have complicated circuit structures, resulting in larger filter sizes, which seriously affects their use in modern high-speed information transmission communication systems. Utility Model Content
[0004] This utility model provides a topology, a wide passband filter, and a communication device, and the main technical problem it solves is that the size of the wide passband filter is too large.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A topology including an input terminal, an output terminal, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a first open-circuit stub, a second open-circuit stub, a first short-circuit stub, a second short-circuit stub, a third short-circuit stub, and a fourth short-circuit stub; wherein, one end of the second parallel line is connected to one end of the first parallel line and one end of the first microstrip line, and the other end of the first parallel line is connected to the first open-circuit stub and the input terminal, and the other end of the first microstrip line... One end is connected to one end of the first short-circuit stub and one end of the second short-circuit stub. The other end of the first short-circuit stub is grounded. The other end of the second parallel line is connected to one end of the second microstrip line and one end of the third parallel line. The other end of the second microstrip line is connected to one end of the third short-circuit stub and one end of the fourth short-circuit stub. The other end of the third short-circuit stub is grounded. The other end of the third parallel line is connected to the output terminal and the second open-circuit stub.
[0006] Optionally, the first parallel line, the second parallel line, the third parallel line, the first short-circuit branch, the second short-circuit branch, the third short-circuit branch, the fourth short-circuit branch, the first open-circuit branch, and the second open-circuit branch are all arranged in parallel.
[0007] Optionally, the first parallel line, the second parallel line, the third parallel line, the first short-circuit stub, the second short-circuit stub, the third short-circuit stub, the fourth short-circuit stub, the first open-circuit stub, and the second open-circuit stub are all perpendicular to the first microstrip line and the second microstrip line.
[0008] Optionally, the electrical lengths of the first parallel line, the second parallel line, and the third parallel line are all equal; the electrical length of the first open-circuit stub is equal to the electrical length of the second open-circuit stub; the electrical lengths of the first microstrip line and the second microstrip line are equal; and the electrical lengths of the first short-circuit stub, the second short-circuit stub, the third short-circuit stub, and the fourth short-circuit stub are all equal.
[0009] Optionally, the electrical lengths of the first parallel line, the second parallel line, and the third parallel line are all equal to a quarter wavelength corresponding to the center frequency of the broadband bandpass filter; the electrical lengths of the first open stub and the second open stub are both a quarter wavelength corresponding to the center frequency of the notch filter, and also a quarter wavelength corresponding to the center frequency of the broadband bandpass filter.
[0010] Optionally, the sum of the electrical length of the first microstrip line and the electrical length of the first short-circuit stub is greater than a quarter wavelength corresponding to the center frequency of the broadband bandpass filter.
[0011] Optionally, the odd-mode characteristic impedance of the first parallel line is equal to the odd-mode characteristic impedance of the third parallel line; the even-mode characteristic impedance of the first parallel line is equal to the even-mode characteristic impedance of the third parallel line; the characteristic impedance of the first open-circuit stub is equal to the characteristic impedance of the second open-circuit stub; the characteristic impedance of the first microstrip line is equal to the characteristic impedance of the second microstrip line; and the characteristic impedances of the first short-circuit stub, the second short-circuit stub, the third short-circuit stub, and the fourth short-circuit stub are all equal.
[0012] Optionally, the characteristic impedances of the first short-circuit stub, the second short-circuit stub, the third short-circuit stub, and the fourth short-circuit stub are all twice the characteristic impedance of the first microstrip line.
[0013] To solve the above-mentioned technical problems, another technical solution adopted by this utility model is to provide a wide passband filter, which is obtained through the above-mentioned topology design.
[0014] To solve the above-mentioned technical problems, another technical solution adopted by this utility model is: to provide a communication device including the aforementioned wideband filter.
[0015] The beneficial effects of this utility model embodiment are as follows: Unlike the prior art, this utility model embodiment provides a topology including an input terminal, an output terminal, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a first open-circuit stub, a second open-circuit stub, a first short-circuit stub, a second short-circuit stub, a third short-circuit stub, and a fourth short-circuit stub; wherein, one end of the second parallel line is connected to one end of the first parallel line and one end of the first microstrip line, and the other end of the first parallel line is connected to the first open-circuit stub and the input terminal, and the first microstrip line... The other end of the strip line is connected to one end of the first short-circuited stub and one end of the second short-circuited stub. The other end of the first short-circuited stub is grounded, and the other end of the second short-circuited stub is grounded. The other end of the second parallel line is connected to one end of the second microstrip line and one end of the third parallel line. The other end of the second microstrip line is connected to one end of the third short-circuited stub and one end of the fourth short-circuited stub. The other end of the third short-circuited stub is grounded, and the other end of the fourth short-circuited stub is grounded. The other end of the third parallel line is connected to the output terminal and the second open-circuited stub. Based on the above topology, the wide passband filter has eight transmission poles to ensure flatness within its band, five transmission zeros in the stopband to ensure high selectivity and high isolation, and one transmission zero in the passband to form the required notch. This gives the wide passband filter the advantage of miniaturization. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the topology provided in an embodiment of the present utility model;
[0018] Figure 2 This is a schematic diagram of the odd-mode topology provided in this embodiment of the utility model;
[0019] Figure 3 This is a schematic diagram of the even-mode topology provided in this embodiment of the utility model;
[0020] Figure 4 This is a schematic diagram of the layout of a wide passband filter based on topology design provided in an embodiment of this utility model;
[0021] Figure 5This is a diagram showing the layout of a wide passband filter based on topology design provided in this embodiment of the invention.
[0022] Figure 6 This is a simulation result diagram of the S-parameters of a wide passband filter based on topology design provided in this embodiment of the present invention. Detailed Implementation
[0023] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.
[0024] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.
[0025] Please see Figure 1 The topology 100 includes: an input terminal 101, an output terminal 102, a first parallel line 103, a second parallel line 104, a third parallel line 105, a first microstrip line 106, a second microstrip line 107, a first open-circuit stub 108, a second open-circuit stub 109, a first short-circuit stub 110, a second short-circuit stub 111, a third short-circuit stub 112, and a fourth short-circuit stub 113; wherein, one end of the second parallel line 104 is connected to one end of the first parallel line 103 and one end of the first microstrip line 106, and the other end of the first parallel line 103 is connected to the first open-circuit stub 108 and the input terminal 101, and the first microstrip line 106... The other end of 6 is connected to one end of the first short-circuit stub 110 and one end of the second short-circuit stub 111. The other end of the first short-circuit stub 110 is grounded, and the other end of the second short-circuit stub 111 is grounded. The other end of the second parallel line 104 is connected to one end of the second microstrip line 107 and one end of the third parallel line 105. The other end of the second microstrip line 107 is connected to one end of the third short-circuit stub 112 and one end of the fourth short-circuit stub 113. The other end of the third short-circuit stub 112 is grounded, and the other end of the fourth short-circuit stub 113 is grounded. The other end of the third parallel line 105 is connected to the output terminal 102 and the second open-circuit stub 109.
[0026] It should be noted that the following connection methods are included but are not limited to: (1) Connecting one end of the second parallel line 104 to one end of the first parallel line 103 and one end of the first microstrip line 106; (2) Connecting the other end of the first parallel line 103 to the first open-circuit stub 108 and the input terminal 101; (3) Connecting the other end of the first microstrip line 106 to one end of the first short-circuit stub 110 and one end of the second short-circuit stub 111; (4) Connecting the other end of the second parallel line 104 to one end of the second microstrip line 107 and one end of the third parallel line 105; (5) Connecting the other end of the second microstrip line 107 to one end of the third short-circuit stub 112 and one end of the fourth short-circuit stub 113; and (6) Connecting the other end of the third parallel line 105 to the output terminal 102 and the second open-circuit stub 109. There are connection points between them, namely, one end of the second parallel line 104 intersects with one end of the first parallel line 103 and one end of the first microstrip line 106; the other end of the first parallel line 103 intersects with the first open-circuit stub 108 and the input terminal 101; the other end of the first microstrip line 106 intersects with one end of the first short-circuit stub 110 and one end of the second short-circuit stub 111; the other end of the second parallel line 104 intersects with one end of the second microstrip line 107 and one end of the third parallel line 105; the other end of the second microstrip line 107 intersects with one end of the third short-circuit stub 112 and one end of the fourth short-circuit stub 113; and the other end of the third parallel line 105 intersects with the output terminal 102 and the second open-circuit stub 109.
[0027] Alternatively, they can be connected independently, that is, physically separated when one end of the first parallel line 103 and one end of the first microstrip line 106 are connected to one end of the second parallel line 104; physically separated when the first open-circuit stub 108 and the input terminal 101 are connected to the other end of the first parallel line 103; physically separated when one end of the first short-circuit stub 110 and one end of the second short-circuit stub 111 are connected to the other end of the first microstrip line 106; physically separated when one end of the second microstrip line 107 and one end of the third parallel line 105 are connected to the other end of the second parallel line 104; physically separated when one end of the third short-circuit stub 112 and one end of the fourth short-circuit stub 113 are connected to the other end of the second microstrip line 107; and physically separated when the output terminal 102 and the second open-circuit stub 109 are connected to the other end of the third parallel line 105.
[0028] As an example, in this embodiment, a connection method with intersection points is preferred.
[0029] In some embodiments, the first parallel line 103, the second parallel line 104, the third parallel line 105, the first short-circuit branch 110, the second short-circuit branch 111, the third short-circuit branch 112, the fourth short-circuit branch 113, the first open-circuit branch 108, and the second open-circuit branch 109 are all arranged in parallel.
[0030] Please refer to the following: Figure 4 The first parallel line 103 mentioned above includes a first transmission line 1031 and a second transmission line 1032 that are parallel to each other; the second parallel line 104 includes a third transmission line 1041 and a fourth transmission line 1042 that are parallel to each other; the third parallel line 105 includes a fifth transmission line 1051 and a sixth transmission line 1052 that are parallel to each other.
[0031] In some embodiments, the first parallel line 103, the second parallel line 104, the third parallel line 105, the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, the fourth short-circuit stub 113, the first open-circuit stub 108, and the second open-circuit stub 109 are all perpendicular to the first microstrip line 106 and the second microstrip line 107.
[0032] In some embodiments, the electrical lengths of the first parallel line 103, the second parallel line 104, and the third parallel line 105 are all equal; the electrical length of the first open-circuit stub 108 is equal to the electrical length of the second open-circuit stub 109; the electrical lengths of the first microstrip line 106 and the second microstrip line 107 are equal; and the electrical lengths of the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, and the fourth short-circuit stub 113 are all equal.
[0033] Furthermore, the electrical lengths of the first parallel line 103, the second parallel line 104, and the third parallel line 105 are all equal to a quarter wavelength corresponding to the center frequency of the broadband bandpass filter; the electrical lengths of the first open-circuit stub 108 and the second open-circuit stub 109 are both a quarter wavelength corresponding to the center frequency of the notch filter, and also a quarter wavelength corresponding to the center frequency of the broadband bandpass filter. Moreover, the sum of the electrical lengths of the first microstrip line 106 and the first short-circuit stub 110 is greater than a quarter wavelength corresponding to the center frequency of the broadband bandpass filter.
[0034] In some embodiments, the odd-mode characteristic impedance of the first parallel line 103 and the odd-mode characteristic impedance of the third parallel line 105 are equal, denoted as Z. o1 The even-mode characteristic impedance of the first parallel line 103 and the even-mode characteristic impedance of the third parallel line 105 are equal, denoted as Z. e1 The odd-mode characteristic impedance of the second parallel line is denoted as Z. o2 The even-mode characteristic impedance of the second parallel line is denoted as Z. e2The characteristic impedances of the first open-circuit stub 108 and the second open-circuit stub 109 are equal, denoted as Z1; the characteristic impedances of the first microstrip line 106 and the second microstrip line 107 are equal, denoted as Z2; the characteristic impedances of the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, and the fourth short-circuit stub 113 are all equal.
[0035] Furthermore, the characteristic impedances of the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, and the fourth short-circuit stub 113 are all twice the characteristic impedance of the first microstrip line 106, denoted as 2Z2.
[0036] This utility model provides a topology 100 including: an input terminal 101, an output terminal 102, a first parallel line 103, a second parallel line 104, a third parallel line 105, a first microstrip line 106, a second microstrip line 107, a first open-circuit stub 108, a second open-circuit stub 109, a first short-circuit stub 110, a second short-circuit stub 111, a third short-circuit stub 112, and a fourth short-circuit stub 113; wherein, one end of the second parallel line 104 is connected to one end of the first parallel line 103 and one end of the first microstrip line 106, and the other end of the first parallel line 103 is connected to the first open-circuit stub 108 and the input terminal 101, and the first microstrip line 106... The other end of the stripline 106 is connected to one end of the first short-circuit stub 110 and one end of the second short-circuit stub 111. The other end of the first short-circuit stub 110 is grounded, and the other end of the second short-circuit stub 111 is grounded. The other end of the second parallel line 104 is connected to one end of the second microstrip line 107 and one end of the third parallel line 105. The other end of the second microstrip line 107 is connected to one end of the third short-circuit stub 112 and one end of the fourth short-circuit stub 113. The other end of the third short-circuit stub 112 is grounded, and the other end of the fourth short-circuit stub 113 is grounded. The other end of the third parallel line 105 is connected to the output terminal 102 and the second open-circuit stub 109. The wide passband filter designed using the above topology 100 has the advantage of miniaturization.
[0037] To facilitate understanding, the following provides an approach to designing a miniaturized wideband filter based on the aforementioned topology 100. Please refer to [link / reference needed]. Figures 2 to 5 The details are as follows:
[0038] Since the topology 100 can be equivalent to a symmetrical structure, its transmission poles can be calculated using the even / odd mode method. To simplify the calculation process, it is first assumed that the sum of the electrical length of the first microstrip line 106 and the electrical length of the first short-circuit stub 110 is one-quarter wavelength corresponding to the center frequency of the broadband bandpass filter. At this point, Figure 2This is the odd-mode form of the topology 100, where the electrical length of the odd-mode transmission line is the electrical length of the second parallel line 104; and the characteristic impedance of the odd-mode transmission line is the odd-mode characteristic impedance of the second parallel line 104.
[0039] When Y ino When f = 0, it can be concluded that the topology 100 has four odd-mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the four odd-mode transmission poles are as follows:
[0040]
[0041] in:
[0042] Δ1=2Z2(Z e1 -Z o1 ) 2
[0043] Δ2=4Z2Z o2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +
[0044] Z o2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )
[0045] Δ3=4Z o1 Z e1 Z o2 +Z1Z o2
[0046] Figure 3 This is the even-mode form of the topology 100, wherein the electrical length of the even-mode transmission line is the electrical length of the second parallel line 104; and the characteristic impedance of the even-mode transmission line is the even-mode characteristic impedance of the second parallel line 104.
[0047] When Y ine When f = 0, it can be concluded that the topology 100 has four even-mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the four even-mode transmission poles are as follows:
[0048]
[0049] in:
[0050] Δ1=2Z2(Z e1 -Z o1 ) 2
[0051] Δ2=4Z2Z e2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +
[0052] Z e2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )
[0053] Δ3=4Z o1 Z e1 Z e2 +Z1Z e2
[0054] For this topology 100, its transmission zeros can be calculated as follows: Multiply the ABCD matrices of the cascaded resonators that make up the topology 100 sequentially to obtain the corresponding ABCD matrix of the topology 100; then convert the ABCD matrix of the topology 100 into the corresponding S matrix. When |S 21 When | = 0, it can be concluded that this topology 100 has three transmission zeros, and the frequencies corresponding to the three transmission zeros are as follows:
[0055] f z1 =0
[0056] f z2 =f0
[0057] f z3 =2f0
[0058] From the above analysis, it can be seen that when the sum of the electrical length of the first microstrip line 106 and the electrical length of the first short-circuit stub 110 is also a quarter wavelength corresponding to the center frequency of the broadband bandpass filter, the topology 100 has four odd-mode transmission poles, three even-mode transmission poles, and three transmission zeros. Returning to the original topology 100, appropriately increasing the sum of the electrical lengths of the first microstrip line 106 and the first short-circuit stub 110 will additionally add three transmission zeros (f...). z4 f z5 f z6 However, the original number of zeros and poles remains unchanged. And regardless of how the parameter Z is changed... o1 Z e1 Z o2 Z e2 The values of Z1 and Z2, and the relative positions of the transmission zeros and poles, i.e., f z1 <f z4 <f ep1 <fop1 <f op2 <f ep2 <f z2 <f ep3 <f op3 <f op4 <f ep4 <f z5 <f z3 <f z6 None of these will change. Therefore, based on this topology 100, a broadband bandpass filter with notch characteristics can be designed, with eight transmission poles in the passband to ensure its in-band flatness, five transmission zeros in the stopband to ensure high selectivity and high isolation, and one transmission zero in the passband to form the required notch.
[0059] To verify the concept of this utility model, a simulation experiment of a wide passband filter embodiment is also provided, as detailed below:
[0060] As shown in the figure, the wideband filter is designed using the aforementioned topology 100 and mounted on a circuit board. The structure and function of topology 100 can be found in the above embodiments, and will not be repeated here. The specified circuit board has a dielectric constant of 3.38, a dielectric loss of 0.0022, and a thickness of 0.813 mm. Its layout is shown in the figure. Figure 4 and Figure 5 As shown. The entire layout is only 34.8mm * 10.8mm in size, and the specific dimensions of the filter are: l P1 =9.2mm,s P1 =0.1mm,w P1 =0.2mm,l P2 =9.2mm,s P2 =0.15mm,w P2 =0.25mm, l1=9.1mm, l2=4.3mm, l3=6.0mm, w1=0.3mm, w2=1.8mm, w3=0.9mm, s1=0.15mm.
[0061] in:
[0062] l P1 This indicates the physical length of the first parallel line 103 or the physical length of the third parallel line 105;
[0063] s P1 This indicates the spacing between the first transmission line 1031 and the second transmission line 1032 that make up the first parallel line 103, or the spacing between the fifth transmission line 1051 and the sixth transmission line 1052 that make up the third parallel line 105.
[0064] w P1This indicates the physical width of the first transmission line 1031, the second transmission line 1032, the fifth transmission line 1051, or the sixth transmission line 1052.
[0065] l P2 This indicates the physical length of the second parallel line 104;
[0066] s P2 This indicates the spacing between the third transmission line 1041 and the fourth transmission line 1042 that make up the second parallel line 104;
[0067] w P2 This indicates the physical width of the third transmission line 1041 or the physical width of the fourth transmission line 1042;
[0068] l1 represents the physical length of the first open branch 108 or the physical length of the second open branch 109;
[0069] l2 represents the physical length of the first microstrip line 106 or the physical length of the second microstrip line 107;
[0070] l3 represents the physical length of the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, or the fourth short-circuit stub 113.
[0071] w1 represents the physical width of the first open branch 108 or the width of the second open branch 109;
[0072] w2 represents the physical width of the first microstrip line 106 or the physical width of the second microstrip line 107;
[0073] w3 represents the physical width of the first short-circuit stub 110, the second short-circuit stub 111, the third short-circuit stub 112, or the fourth short-circuit stub 113.
[0074] s1 represents the distance between the first open branch 108 and the first parallel line 103, or the distance between the second open branch 109 and the third parallel line 105.
[0075] The S-parameter simulation results are as follows: Figure 6As shown, its passband range with a reflection coefficient better than -10dB is 2.47GHz to 7.75GHz, with a center frequency of 5.11GHz, an absolute bandwidth of 5.28GHz, and a relative bandwidth of 103.3%. Furthermore, it features seven transmission poles within the passband, located at 2.52GHz, 2.9GHz, 3.85GHz, 4.41GHz, 5.85GHz, 7.32GHz, and 7.68GHz, ensuring passband flatness. It also has a transmission zero at 5.34GHz to form the required notch, with an isolation of 28.6dB at the notch center frequency, demonstrating good isolation. In the stopband, it has five transmission zeros located at 0GHz, 0.74GHz, 8.99GHz, 11.36GHz, and 11.84GHz, ensuring high selectivity and high stopband isolation.
[0076] Through the simulation examples of the above topology 100, it can be demonstrated that the wide passband filter designed based on the above topology 100 has the characteristic of miniaturization.
[0077] This utility model also provides embodiments of communication devices, which include the wide passband filter described above. For the specific structure and function of the wide passband filter, please refer to the above embodiments, which will not be repeated here.
[0078] It should be noted that while the preferred embodiments of this utility model are provided in the specification and accompanying drawings, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this utility model; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this utility model. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this utility model specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A topology, characterized in that, Comprise: an input terminal, an output terminal, a first parallel line, a second parallel line, a third parallel line, a first microstrip line, a second microstrip line, a first open stub, a second open stub, a first short stub, a second short stub, a third short stub and a fourth short stub; wherein one end of the second parallel line is connected with one end of the first parallel line and one end of the first microstrip line, the other end of the first parallel line is connected with the first open stub and the input terminal, the other end of the first microstrip line is connected with one end of the first short stub and one end of the second short stub, the other end of the first short stub is grounded, the other end of the second short stub is grounded, the other end of the second parallel line is connected with one end of the second microstrip line and one end of the third parallel line, the other end of the second microstrip line is connected with one end of the third short stub and one end of the fourth short stub, the other end of the third short stub is grounded, the other end of the fourth short stub is grounded, and the other end of the third parallel line is connected with the output terminal and the second open stub.
2. The topology structure according to claim 1, wherein: the first parallel line, the second parallel line, the third parallel line, the first short stub, the second short stub, the third short stub, the fourth short stub, the first open stub and the second open stub are arranged in parallel.
3. The topology structure according to claim 2, wherein: the first parallel line, the second parallel line, the third parallel line, the first short stub, the second short stub, the third short stub, the fourth short stub, the first open stub and the second open stub are perpendicular to the first microstrip line and the second microstrip line.
4. The topology structure according to claim 1, wherein: the electrical length of the first parallel line, the electrical length of the second parallel line and the electrical length of the third parallel line are equal; the electrical length of the first open stub is equal to the electrical length of the second open stub; the electrical length of the first microstrip line is equal to the electrical length of the second microstrip line; the electrical length of the first short stub, the electrical length of the second short stub, the electrical length of the third short stub and the electrical length of the fourth short stub are equal.
5. The topology structure according to claim 4, wherein: the electrical length of the first parallel line, the electrical length of the second parallel line and the electrical length of the third parallel line are equal to the corresponding quarter wavelength at the center frequency of the wideband bandpass filter; the electrical length of the first open stub and the electrical length of the second open stub are both the quarter wavelength corresponding to the notch center frequency and the quarter wavelength corresponding to the center frequency of the wideband bandpass filter.
6. The topology structure according to claim 4, wherein: the sum of the electrical length of the first microstrip line and the electrical length of the first short stub is greater than the quarter wavelength corresponding to the center frequency of the wideband bandpass filter.
7. The topology structure according to claim 1, wherein: an odd mode characteristic impedance of the first parallel line is equal to an odd mode characteristic impedance of the third parallel line; an even mode characteristic impedance of the first parallel line is equal to an even mode characteristic impedance of the third parallel line; a characteristic impedance of the first open stub is equal to a characteristic impedance of the second open stub; a characteristic impedance of the first microstrip line is equal to a characteristic impedance of the second microstrip line; characteristic impedances of the first, second, third and fourth short stubs are all equal.
8. The topology of claim 7, wherein, characteristic impedances of the first, second, third and fourth short stubs are all twice a characteristic impedance of the first microstrip line.
9. A wide passband filter characterized by, by the topology design of any one of claims 1-8.
10. A communication device comprising the wide passband filter of claim 9.