Topological structure, band-pass filter and communication equipment

Abstract

The utility model relates to a topological structure, a band-pass filter and communication equipment. One end of a second microstrip line in the topological structure is connected between the first parallel line and the second parallel line, and the other end of the second microstrip line is connected with a third microstrip line. One end of the sixth microstrip line is connected between the first parallel line and the second parallel line, and the other end of the sixth microstrip line is connected with the seventh microstrip line. One end of the fifth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the fifth microstrip line is connected with the fourth microstrip line. One end of the ninth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the ninth microstrip line is connected with the eighth microstrip line. One end of the first short-circuit branch is connected between the third microstrip line and the fourth microstrip line. And one end of the second short-circuit branch knot is connected between the seventh microstrip line and the eighth microstrip line. Wherein the second microstrip line, the third microstrip line and the first short circuit branch are used for optimizing an in-band reflection coefficient, and an additional transmission zero point is introduced to ensure high selectivity and high isolation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication equipment, and particularly relates to a topology, a band-pass filter and communication equipment. BACKGROUND

[0002] With the rapid popularization of the fifth generation mobile communication technology (5G for short), the research and development of high-speed data transmission demand and efficient spectrum resource utilization broadband communication system is an inevitable trend of the development of the communication industry. The band-pass filter is a key device of the communication system, and the research on the band-pass filter with the characteristics of high-speed transmission signal and notch has a very high scientific research and commercial value. However, most of the reported band-pass filters with the characteristics of notch have poor selectivity, which limits the application of the band-pass filter in the modern wireless communication system. CONTENT OF THE UTILITY MODEL

[0003] The present application provides a topology, a band-pass filter and communication equipment, and aims to solve the problem of poor selectivity of the wideband band-pass filter.

[0004] In a first aspect, the embodiments of the present application provide a topology structure, comprising an input end and an output end, a first parallel line, a second parallel line and a third parallel line are connected between the input end and the output end, the first parallel line is connected between the input end and the second parallel line, and the third parallel line is connected between the second parallel line and the output end. The first parallel line and the second parallel line further comprise a second microstrip line and a sixth microstrip line, one end of the second microstrip line is connected between the first parallel line and the second parallel line, and the other end of the second microstrip line is connected to a third microstrip line; one end of the sixth microstrip line is connected between the first parallel line and the second parallel line, and the other end of the sixth microstrip line is connected to a seventh microstrip line. The second parallel line and the third parallel line further comprise a fifth microstrip line and a ninth microstrip line, one end of the fifth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the fifth microstrip line is connected to a fourth microstrip line; one end of the ninth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the ninth microstrip line is connected to an eighth microstrip line. The topology structure further comprises a first short-circuit stub, one end of the first short-circuit stub is connected between the third microstrip line and the fourth microstrip line, and the other end of the first short-circuit stub is grounded. The topology structure further comprises a second short-circuit stub, one end of the second short-circuit stub is connected between the seventh microstrip line and the eighth microstrip line, and the other end of the second short-circuit stub is grounded. The topology structure further comprises a first open-circuit stub and a first microstrip line, the first open-circuit stub is connected between the input end and the first parallel line through the first microstrip line. The topology structure further comprises a second open-circuit stub and a tenth microstrip line, the second open-circuit stub is connected between the output end and the third parallel line through the tenth microstrip line.

[0005] In some embodiments, the first parallel line comprises a first transmission line and a second transmission line arranged in parallel, the second parallel line comprises a third transmission line and a fourth transmission line arranged in parallel, and the third parallel line comprises a fifth transmission line and a sixth transmission line arranged in parallel. One end of the first transmission line is connected to the input end and one end of the first microstrip line. One end of the second transmission line is connected to one end of the second microstrip line, one end of the sixth microstrip line and one end of the third transmission line. One end of the fourth transmission line is connected to one end of the fifth microstrip line, one end of the ninth microstrip line and one end of the fifth transmission line. One end of the sixth transmission line is connected to one end of the tenth microstrip line and the output end. The other end of the first transmission line, the other end of the second transmission line, the other end of the third transmission line, the other end of the fourth transmission line, the other end of the fifth transmission line and the other end of the sixth transmission line are open.

[0006] In some embodiments, the first parallel line, the second parallel line, the third parallel line, the first microstrip line, the third microstrip line, the fourth microstrip line, the seventh microstrip line, the eighth microstrip line, and the tenth microstrip line are arranged in parallel.

[0007] In some embodiments, the first parallel line, the second parallel line, the third parallel line, the first microstrip line, the third microstrip line, the fourth microstrip line, the seventh microstrip line, the eighth microstrip line, and the tenth microstrip line are all perpendicular to the second microstrip line, the fifth microstrip line, the sixth microstrip line, the ninth microstrip line, the first open-circuit stub, the second open-circuit stub, the first short-circuit stub, and the second short-circuit stub.

[0008] In some embodiments, the first parallel line, the second parallel line, and the third parallel line have equal electrical lengths. Based on the bandpass filter of the topology, the electrical lengths of the first parallel line, the second parallel line, and the third parallel line are equal to corresponding quarter wavelengths at a center frequency of the bandpass filter.

[0009] In some embodiments, the first microstrip line and the tenth microstrip line have equal electrical lengths, and the first open-circuit stub and the second open-circuit stub have equal electrical lengths. The sum of the electrical length of the first microstrip line and the electrical length of the first open-circuit stub is equal to a quarter wavelength at a notch center frequency.

[0010] In some embodiments, the second microstrip line and the ninth microstrip line have equal electrical lengths. The third microstrip line and the eighth microstrip line have equal electrical lengths. The fourth microstrip line and the seventh microstrip line have equal electrical lengths. The fifth microstrip line and the sixth microstrip line have equal electrical lengths. The first short-circuit stub and the second short-circuit stub have equal electrical lengths. The sum of the electrical length of the second microstrip line and the electrical length of the third microstrip line is equal to the sum of the electrical length of the fourth microstrip line and the electrical length of the fifth microstrip line. Based on the bandpass filter of the topology, 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 first short-circuit stub is greater than a corresponding quarter wavelength at a center frequency of the bandpass filter.

[0011] In some embodiments, 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 microstrip line, the characteristic impedance of the tenth microstrip line, the characteristic impedance of the first open stub, and the characteristic impedance of the second open stub are equal. The characteristic impedance of the first short stub and the characteristic impedance of the second short stub are equal. The characteristic impedance of the second microstrip line, the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line, the characteristic impedance of the fifth microstrip line, the characteristic impedance of the sixth microstrip line, the characteristic impedance of the seventh microstrip line, the characteristic impedance of the eighth microstrip line, and the characteristic impedance of the ninth microstrip line are equal.

[0012] In a second aspect, embodiments of the present application provide a bandpass filter designed by the topology structure of any one of the first aspect.

[0013] In a third aspect, embodiments of the present application provide a communication device comprising the bandpass filter of the second aspect.

[0014] In some embodiments, 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 microstrip line, the characteristic impedance of the tenth microstrip line, the characteristic impedance of the first open stub, and the characteristic impedance of the second open stub are equal. The characteristic impedance of the first short stub and the characteristic impedance of the second short stub are equal. The characteristic impedance of the second microstrip line, the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line, the characteristic impedance of the fifth microstrip line, the characteristic impedance of the sixth microstrip line, the characteristic impedance of the seventh microstrip line, the characteristic impedance of the eighth microstrip line, and the characteristic impedance of the ninth microstrip line are equal. Attached Figure Description

[0015] Figure 1 These are schematic diagrams of some topological structures provided in the embodiments of this application;

[0016] Figure 2 These are schematic diagrams of some topological structures provided in the embodiments of this application;

[0017] Figure 3 These are schematic diagrams of odd modulus topologies provided in embodiments of this application;

[0018] Figure 4 These are schematic diagrams of even-mode topologies provided in embodiments of this application;

[0019] Figure 5 This is a schematic diagram of the layout of some bandpass filters provided in the embodiments of this application;

[0020] Figure 6 This is a schematic diagram of the layout of some bandpass filters provided in the embodiments of this application;

[0021] Figure 7 These are simulation and test results of the S-parameters of some bandpass filters provided in the embodiments of this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] 10. Topology; 11. Input terminal; 12. Output terminal; 13. First parallel line; 131. First transmission line; 132. Second transmission line; 14. Second parallel line; 141. Third transmission line; 142. Fourth transmission line; 15. Third parallel line; 151. Fifth transmission line; 152. Sixth transmission line; 16. First open-circuit stub; 17. Second open-circuit stub; 18. First short-circuit stub; 19. Second short-circuit stub; 21. First microstrip line; 22. Second microstrip line; 23. Third microstrip line; 24. Fourth microstrip line; 25. Fifth microstrip line; 26. Sixth microstrip line; 27. Seventh microstrip line; 28. Eighth microstrip line; 29. ​​Ninth microstrip line; 31. Tenth microstrip line; 32. Third short-circuit stub; 33. Fourth short-circuit stub. Detailed Implementation

[0024] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "several" is more than one, unless otherwise explicitly specified.

[0026] In the description of the embodiments of the present application, the term "and / or" is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0027] In this paper, "embodiment" means that the specific features, structures or properties described in conjunction with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment independent of or alternative to other embodiments. In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] First, please refer to Figure 1 , Figure 1 is a schematic diagram of some topologies 10 provided by embodiments of the present application, which includes an input end 11, an output end 12, a first parallel line 13, a second parallel line 14, a third parallel line 15, a first microstrip line 21, a second microstrip line 22, a third microstrip line, a fourth microstrip line 24, a fifth microstrip line 25, a sixth microstrip line 26, a seventh microstrip line 27, an eighth microstrip line 28, a ninth microstrip line 29, a first open stub 16, a second open stub 17, a first short stub 18 and a second short stub 19.

[0029] Specifically, please refer to Figure 1 , the first parallel line 13, the second parallel line 14 and the third parallel line 15 are connected between the input end 11 and the output end 12, the first parallel line 13 is connected between the input end 11 and the second parallel line 14, and the third parallel line 15 is connected between the second parallel line 14 and the output end 12.

[0030] The first parallel line 13 and the second parallel line 14 further include a second microstrip line 22 and a sixth microstrip line 26, one end of the second microstrip line 22 is connected between the first parallel line 13 and the second parallel line 14, and the other end of the second microstrip line 22 is connected to the third microstrip line. One end of the sixth microstrip line 26 is connected between the first parallel line 13 and the second parallel line 14, and the other end of the sixth microstrip line 26 is connected to the seventh microstrip line 27.

[0031] The second parallel line 14 and the third parallel line 15 further comprise a fifth microstrip line 25 and a ninth microstrip line 29. One end of the fifth microstrip line 25 is connected between the second parallel line 14 and the third parallel line 15, and the other end of the fifth microstrip line 25 is connected to the fourth microstrip line 24. One end of the ninth microstrip line 29 is connected between the second parallel line 14 and the third parallel line 15, and the other end of the ninth microstrip line 29 is connected to the eighth microstrip line 28.

[0032] The third microstrip line and the fourth microstrip line 24 further comprise a first short-circuit stub 18. One end of the first short-circuit stub 18 is connected between the third microstrip line and the fourth microstrip line 24, and the other end of the first short-circuit stub 18 is grounded. The seventh microstrip line 27 and the eighth microstrip line 28 further comprise a second short-circuit stub 19. One end of the second short-circuit stub 19 is connected between the seventh microstrip line 27 and the eighth microstrip line 28, and the other end of the second short-circuit stub 19 is grounded.

[0033] The input terminal 11 and the first parallel line 13 further comprise a first open-circuit stub 16 and a first microstrip line 21. The first open-circuit stub 16 is connected between the input terminal 11 and the first parallel line 13 through the first microstrip line 21. The output terminal 12 and the third parallel line 15 further comprise a second open-circuit stub 17 and a tenth microstrip line 31. The second open-circuit stub 17 is connected between the output terminal 12 and the third parallel line 15 through the tenth microstrip line 31. The first open-circuit stub 16 and the second open-circuit stub 17 are bent to realize miniaturization of the wideband filter.

[0034] In some embodiments, referring to Figure 1 and Figure 2 The first parallel line 13 comprises a first transmission line 131 and a second transmission line 132 arranged in parallel. The second parallel line 14 comprises a third transmission line 141 and a fourth transmission line 142 arranged in parallel. The third parallel line 15 comprises a fifth transmission line 151 and a sixth transmission line 152 arranged in parallel. One end of the first transmission line 131 is connected to the input terminal 11 and one end of the first microstrip line 21. One end of the second transmission line 132 is connected to one end of the second microstrip line 22, one end of the sixth microstrip line 26, and one end of the third transmission line 141. One end of the fourth transmission line 142 is connected to one end of the fifth microstrip line 25, one end of the ninth microstrip line 29, and one end of the fifth transmission line 151. One end of the sixth transmission line 152 is connected to one end of the tenth microstrip line 31 and the output terminal 12. The other end of the first transmission line 131, the other end of the second transmission line 132, the other end of the third transmission line 141, the other end of the fourth transmission line 142, the other end of the fifth transmission line 151, and the other end of the sixth transmission line 152 are open-circuited.

[0035] In some embodiments, referring to Figure 1The first parallel line 13, the second parallel line 14, the third parallel line 15, the first microstrip line 21, the third microstrip line, the fourth microstrip line 24, the seventh microstrip line 27, the eighth microstrip line 28, and the tenth microstrip line 31 are parallel.

[0036] In some embodiments, referring to Figure 1 The first parallel line 13, the second parallel line 14, the third parallel line 15, the first microstrip line 21, the third microstrip line, the fourth microstrip line 24, the seventh microstrip line 27, the eighth microstrip line 28, and the tenth microstrip line 31 are perpendicular to the second microstrip line 22, the fifth microstrip line 25, the sixth microstrip line 26, the ninth microstrip line 29, the first open stub 16, the second open stub 17, the first short stub 18, and the second short stub 19.

[0037] In some embodiments, the electrical length of the first parallel line 13, the electrical length of the second parallel line 14, and the electrical length of the third parallel line 15 are equal and are θ. Based on the bandpass filter of the topology 10, the electrical length of the first parallel line 13, the electrical length of the second parallel line 14, and the electrical length of the third parallel line 15 are equal to the corresponding quarter wavelength at the center frequency of the bandpass filter.

[0038] In some embodiments, the electrical length of the first microstrip line 21 and the electrical length of the tenth microstrip line 31 are equal and are θ1, and the electrical length of the first open stub 16 and the electrical length of the second open stub 17 are equal and are θ2. The sum of the electrical length of the first microstrip line 21 and the electrical length of the first open stub 16 is the quarter wavelength corresponding to the notch center frequency, i.e., θ1+θ2=θ.

[0039] In some embodiments, the electrical length of the second microstrip line 22 and the electrical length of the ninth microstrip line 29 are equal and are θ3. The electrical length of the third microstrip line and the electrical length of the eighth microstrip line 28 are equal and are θ4. The electrical length of the fourth microstrip line 24 and the electrical length of the seventh microstrip line 27 are equal and are θ5. The electrical length of the fifth microstrip line 25 and the electrical length of the sixth microstrip line 26 are equal and are θ6. The electrical length of the first short stub 18 and the electrical length of the second short stub 19 are equal and are θ7. The sum of the electrical length of the second microstrip line 22 and the electrical length of the third microstrip line is equal to the sum of the electrical length of the fourth microstrip line 24 and the electrical length of the fifth microstrip line 25, i.e., θ3+θ4=θ5+θ6. Based on the bandpass filter of the topology 10, the sum of the electrical length of the second microstrip line 22, the electrical length of the third microstrip line, and the electrical length of the first short stub 18 is greater than the corresponding quarter wavelength at the center frequency of the bandpass filter, i.e., θ3+θ4+θ7>θ.

[0040] In some embodiments, the odd-mode characteristic impedance of the first parallel line 13 and the odd-mode characteristic impedance of the third parallel line 15 are equal and are Z o1The even mode characteristic impedance of the first parallel line 13 is equal to the even mode characteristic impedance of the third parallel line 15 and is Z e1 The odd mode characteristic impedance of the second parallel line 14 is Z o2 The even mode characteristic impedance of the second parallel line 14 is Z e2 The characteristic impedance of the first microstrip line 21, the characteristic impedance of the tenth microstrip line 31, the characteristic impedance of the first open stub 16 and the characteristic impedance of the second open stub 17 are equal and are Z1. The characteristic impedance of the first short stub 18 and the characteristic impedance of the second short stub 19 are equal and are Z2. The characteristic impedance of the second microstrip line 22, the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line 24, the characteristic impedance of the fifth microstrip line 25, the characteristic impedance of the sixth microstrip line 26, the characteristic impedance of the seventh microstrip line 27, the characteristic impedance of the eighth microstrip line 28 and the characteristic impedance of the ninth microstrip line 29 are equal and are 2Z2. That is, the characteristic impedance of the second microstrip line 22, the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line 24, the characteristic impedance of the fifth microstrip line 25, the characteristic impedance of the sixth microstrip line 26, the characteristic impedance of the seventh microstrip line 27, the characteristic impedance of the eighth microstrip line 28 and the characteristic impedance of the ninth microstrip line 29 are twice the characteristic impedance of the first short stub 18 and the characteristic impedance of the second short stub 19.

[0041] Based on the analysis of the above topology 10, it can be known that the topology 10 of the embodiment of the present application can be equivalent to a symmetrical structure, and the transmission poles can be calculated by using the even-odd mode equation. In order to simplify the calculation process, first, it is assumed that the sum of the electrical length of the second microstrip line 22, the electrical length of the third microstrip line and the electrical length of the first short stub 18 is equal to the quarter wavelength corresponding to the center frequency of the band-pass filter, that is, θ3+θ4+θ7=θ.

[0042] As Figure 3Some topological structures 10 provided by the embodiments of the present application are shown in the odd mode form of schematic diagram, including an input end 11, a first parallel line 13, a first microstrip line 21, a second microstrip line 22, a third microstrip line, a sixth microstrip line 26, a seventh microstrip line 27, a first open-circuit stub 16, a third short-circuit stub 32, a fourth short-circuit stub 33 and an odd mode transmission line. The first parallel line 13 is arranged between the input end 11 and the odd mode transmission line. The first open-circuit stub 16 is connected between the input end 11 and the first parallel line 13 through the first microstrip line 21. The second microstrip line 22 and the sixth microstrip line 26 are connected between the first parallel line 13 and the odd mode transmission line, one end of the third microstrip line is connected to the second microstrip line 22, the other end of the third microstrip line is connected to the third short-circuit stub 32, and the other end of the third short-circuit stub 32 is grounded. One end of the seventh microstrip line 27 is connected to the sixth microstrip line 26, and the other end of the seventh microstrip line 27 is connected to the fourth short-circuit stub 33, and the other end of the fourth short-circuit stub 33 is grounded. Among them, the first parallel line 13, the first microstrip line 21, the third microstrip line, the seventh microstrip line 27 and the odd mode transmission line are arranged in parallel, and are all perpendicular to the second microstrip line 22, the sixth microstrip line 26, the first open-circuit stub 16, the third short-circuit stub 32 and the fourth short-circuit stub 33.

[0043] Among them, the electrical length of the odd mode transmission line is equal to the electrical length of the second parallel line 14, that is, θ.

[0044] The characteristic impedance of the odd mode transmission line is equal to the odd mode characteristic impedance of the second parallel line 14, that is, Z o2 .

[0045]

[0046] Among them,

[0047] When Y ino = 0, it can be obtained that the topological structure 10 has four transmission poles. When f0 is the center frequency of the band-pass filter, the frequencies corresponding to the four odd mode transmission poles are:

[0048]

[0049] Among them,

[0050] Δ1 = 2Z2(Z e1 -Z o1 ) 2

[0051] Δ2 = 4Z2Z o2 (Z e1 +Z o1 +2) + 8Z2Z o1 Z e1 +

[0052] Zo2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )

[0053] Δ3=4Z o1 Z e1 Z o2 +Z1Z o2

[0054] As Figure 4 shown in some of the topological structures 10 provided by the embodiments of the present application are even mode form schematic diagrams, including an input end 11, a first parallel line 13, a first microstrip line 21, a second microstrip line 22, a third microstrip line, a sixth microstrip line 26, a seventh microstrip line 27, a first open circuit stub 16, a third short circuit stub 32, a fourth short circuit stub 33 and an even mode transmission line. The first parallel line 13 is arranged between the input end 11 and the even mode transmission line. The first open circuit stub 16 is connected between the input end 11 and the first parallel line 13 through the first microstrip line 21. The first parallel line 13 is connected with the second microstrip line 22 and the sixth microstrip line 26 between the first parallel line 13 and the odd mode transmission line, one end of the third microstrip line is connected with the second microstrip line 22, the other end of the third microstrip line is connected with the third short circuit stub 32, and the other end of the third short circuit stub 32 is grounded. One end of the seventh microstrip line 27 is connected with the sixth microstrip line 26, the other end of the seventh microstrip line 27 is connected with the fourth short circuit stub 33, and the other end of the fourth short circuit stub 33 is grounded. Among them, the first parallel line 13, the first microstrip line 21, the third microstrip line, the seventh microstrip line 27 and the even mode transmission line are arranged in parallel, and are all perpendicular to the second microstrip line 22, the sixth microstrip line 26, the first open circuit stub 16, the third short circuit stub 32 and the fourth short circuit stub 33.

[0055] When Y ine = 0, it can be concluded that the topological structure 10 has four transmission poles. When f0 is the center frequency of the band-pass filter, the frequencies corresponding to the four even mode transmission poles are:

[0056]

[0057] Among them,

[0058] Δ1=2Z2(Z e1 -Z o1 ) 2

[0059] Δ2=4Z2Z e2 (Z e1 +Z o1 +2)+8Z2Z o1 Z e1 +

[0060] Z e2 (Z e1 -Z o1 ) 2 +4Z1Z2(Z e1 +Z o1 )

[0061] Δ3=4Z o1 Z e1 Z e2 +Z1Z e2

[0062] For the topology 10, its transmission zeros can be calculated by the following method: multiply the ABCD matrices of the cascade resonators constituting the topology 10 in turn to obtain the ABCD matrix corresponding to the topology 10; convert the ABCD matrix of the topology 10 into the corresponding S matrix. When |S21|=0, it can be concluded that the topology 10 has three transmission zeros, and the frequencies corresponding to the three transmission zeros are respectively:

[0063] f z1 =0

[0064] f z2 =f0

[0065] f z3 =2f0

[0066] From the above analysis, when the sum of the electrical length of the second microstrip line 22, the electrical length of the third microstrip line, and the electrical length of the first short-circuit stub 18 is equal to the corresponding quarter wavelength at the center frequency of the band-pass filter, the topology 10 has four odd-mode transmission poles, four even-mode transmission poles, and three transmission zeros. Returning to the topology 10, appropriately increasing the sum of the electrical length of the second microstrip line 22, the electrical length of the third microstrip line, and the electrical length of the first short-circuit stub 18 will additionally increase three transmission zeros (f z4 , f z5 , f z6 ), but the number of original zeros and poles remains unchanged. And no matter how to change the values of the parameters Z o1 , Z e1 , Z o2 , Z e2 , Z1 and Z2, the relative positions of the transmission zeros and poles, i.e. f z1 < f z4 < f ep1 < f op1 < f op2 < f ep2 < f z2 < f ep3 < f op3 < f op4 < f ep4 < fz5 <f z3 <f z6 None of these will change. Therefore, based on this topology 10, a 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.

[0067] This application provides a topology 10, including an input terminal 11 and an output terminal 12. A first parallel line 13, a second parallel line 14, and a third parallel line 15 connect the input terminal 11 and the output terminal 12. The first parallel line 13 connects the input terminal 11 and the second parallel line 14, and the third parallel line 15 connects the second parallel line 14 and the output terminal 12. A second microstrip line 22 and a sixth microstrip line 26 are also included between the first parallel line 13 and the second parallel line 14. One end of the second microstrip line 22 is connected between the first parallel line 13 and the second parallel line 14, and the other end of the second microstrip line 22 is connected to the third microstrip line. One end of the sixth microstrip line 26 is connected between the first parallel line 13 and the second parallel line 14, and the other end of the sixth microstrip line 26 is connected to a seventh microstrip line 27. The topology 10 also includes a fifth microstrip line 25 and a ninth microstrip line 29 between the second parallel line 14 and the third parallel line 15. One end of the fifth microstrip line 25 is connected between the second parallel line 14 and the third parallel line 15, and the other end of the fifth microstrip line is connected to the fourth microstrip line 24. One end of the ninth microstrip line 29 is connected between the second parallel line 14 and the third parallel line 15, and the other end of the ninth microstrip line 29 is connected to the eighth microstrip line 28. The topology 10 also includes a first short-circuit stub 18, one end of which is connected between the third microstrip line and the fourth microstrip line 24, and the other end of the first short-circuit stub 18 is grounded. The topology 10 also includes a second short-circuit stub 19, one end of which is connected between the seventh microstrip line 27 and the eighth microstrip line 28, and the other end of the second short-circuit stub 19 is grounded. Topology 10 also includes a first open-circuit stub 16 and a first microstrip line 21, with the first open-circuit stub 16 connected between the input terminal 11 and the first parallel line 13 via the first microstrip line 21. Topology 10 also includes a second open-circuit stub 17 and a tenth microstrip line 31, with the second open-circuit stub 17 connected between the output terminal 12 and the third parallel line 15 via the tenth microstrip line 31. The second microstrip line 22, the third microstrip line, and the first short-circuit stub 18 are used to optimize the in-band reflection coefficient and introduce additional transmission zeros to ensure high selectivity and high isolation.

[0068] Secondly, embodiments of this application also provide a bandpass filter, which is obtained through the topology design of any one of the first aspects.

[0069] In order to facilitate the understanding of the concept of the present application, the following simulation experiments are carried out on the physical band-pass filter, which can be arranged on a circuit board. The overall size of the circuit board is 35mmx14.9mm, and the thickness is 0.813mm. The dielectric constant of the circuit board is 3.38, and the dielectric loss is 0.0022. Among them, the first open stub and the second open stub are arranged in a bending manner, which can realize the miniaturization of the wideband filter.

[0070] Please refer to Figure 5 and Figure 6 , the size parameters of the band-pass filter include: l OP represents the physical length of the first parallel line, l OP =9.8mm; wherein the physical length of the first parallel line is equal to the physical length of the third parallel line. s OP represents the distance between the first transmission line and the second transmission line, s OP =0.1mm; wherein the distance between the fifth transmission line and the sixth transmission line is equal to s OP . w OP represents the physical width of the first transmission line, w OP =0.25mm; wherein the physical width of the second transmission line, the physical width of the fifth transmission line and the physical width of the sixth transmission line are equal to the physical width of the first transmission line. l IP represents the physical length of the second parallel line, l IP =9.8mm. s IP represents the distance between the third transmission line and the fourth transmission line, s IP =0.1mm. w IP represents the physical width of the third transmission line, w IP= 0.2mm; wherein the physical width of the fourth transmission line is equal to the physical width of the third transmission line. l1 represents the physical length of the first microstrip line, l1 = 8.4mm; wherein the physical length of the tenth microstrip line is equal to the physical length of the first microstrip line. l2 represents the physical length of the first open-circuited stub, l2 = 2.4mm; wherein the physical length of the second open-circuited stub is equal to the physical length of the first open-circuited stub. l3 represents the physical length of the second microstrip line, l3 = 4.8mm; wherein the physical length of the ninth microstrip line is equal to the physical length of the second microstrip line. l4 represents the physical length of the third microstrip line, l4 = 5.05mm; wherein the physical length of the eighth microstrip line is equal to the physical length of the third microstrip line. l5 represents the physical length of the fifth microstrip line, l5 = 5.1mm; wherein the physical length of the sixth microstrip line is equal to the physical length of the fifth microstrip line. l6 represents the physical length of the fourth microstrip line, l6 = 4.75mm; wherein the physical length of the seventh microstrip line is equal to the physical length of the fourth microstrip line. l7 represents the physical length of the first short-circuited stub, l7 = 0.9mm; wherein the physical length of the second short-circuited stub is equal to the physical length of the first short-circuited stub. w1 represents the physical width of the first microstrip line, w1 = 0.4mm; wherein the physical width of the tenth microstrip line, the physical width of the first open-circuited stub and the physical width of the second open-circuited stub are equal to the physical width of the first microstrip line. w2 represents the physical width of the second microstrip line, w2 = 1.0mm; wherein the physical width of the third microstrip line, the physical width of the fourth microstrip line, the physical width of the fifth microstrip line, the physical width of the sixth microstrip line, the physical width of the seventh microstrip line, the physical width of the eighth microstrip line and the physical width of the ninth microstrip line are equal to the physical width of the second microstrip line. w3 represents the physical width of the first short-circuited stub, w3 = 2.0mm; wherein the physical width of the second short-circuited stub is equal to the physical width of the first short-circuited stub. s1 represents the distance between the sixth transmission line and the tenth microstrip line, s1 = 0.15mm; wherein the distance between the first transmission line and the first microstrip line is equal to s1.

[0071] Figure 7 are the S-parameter simulation and test result graphs of some bandpass filters provided by the embodiments of the present application. From the graphs, it can be seen that the bandpass filters provided by the embodiments of the present application have good performance. Figure 7It can be seen that the filter has a passband range of 2.41GHz to 7.09GHz with a reflection coefficient better than -10dB, a center frequency of 4.75GHz, an absolute bandwidth of 4.68GHz, and a relative bandwidth of 98.5%. In addition, there are six transmission poles in the passband, respectively at 2.46GHz, 2.84GHz, 4.06GHz, 5.14GHz, 6.12GHz and 7.01GHz, which ensure the flatness of the passband. There is also a transmission zero in the passband at 4.82GHz to form the required notch, and the isolation at the center frequency of the notch is 27.3dB, showing good isolation. There are four transmission zeros in the stopband, respectively at 0GHz, 1.66GHz, 7.3GHz and 10.8GHz, which ensure the high selectivity and high isolation of the stopband of the filter.

[0072] In a third aspect, the embodiments of the present application also provide a communication device comprising the bandpass filter of the second aspect, and the structure and functions of the bandpass filter can be referred to the above embodiments, which will not be repeated here.

[0073] It should be noted that the specification and drawings of the utility model provide the preferred embodiments of the utility model, but the utility model can be realized by many different forms, and is not limited to the embodiments described in the specification, and these embodiments are not as additional limitation to the content of the utility model, and the purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive. Furthermore, the above technical features continue to combine, form various embodiments not listed above, and are regarded as the range of the specification of the utility model; further, for those skilled in the art, the above description can be improved or changed, and all these improvements and changes should belong to the protection scope of the utility model claims.

Claims

1. A topology, characterized in that, The topology structure comprises an input end and an output end, a first parallel line, a second parallel line and a third parallel line are connected between the input end and the output end, the first parallel line is connected between the input end and the second parallel line, and the third parallel line is connected between the second parallel line and the output end; The topology structure further comprises a second microstrip line and a sixth microstrip line between the first parallel line and the second parallel line, one end of the second microstrip line is connected between the first parallel line and the second parallel line, and the other end of the second microstrip line is connected to a third microstrip line; one end of the sixth microstrip line is connected between the first parallel line and the second parallel line, and the other end of the sixth microstrip line is connected to a seventh microstrip line; The topology structure further comprises a fifth microstrip line and a ninth microstrip line between the second parallel line and the third parallel line, one end of the fifth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the fifth microstrip line is connected to a fourth microstrip line; one end of the ninth microstrip line is connected between the second parallel line and the third parallel line, and the other end of the ninth microstrip line is connected to an eighth microstrip line; The topology structure further comprises a first short-circuit stub, one end of the first short-circuit stub is connected between the third microstrip line and the fourth microstrip line, and the other end of the first short-circuit stub is grounded; The topology structure further comprises a second short-circuit stub, one end of the second short-circuit stub is connected between the seventh microstrip line and the eighth microstrip line, and the other end of the second short-circuit stub is grounded; The topology structure further comprises a first open-circuit stub and a first microstrip line, the first open-circuit stub is connected between the input end and the first parallel line through the first microstrip line; The topology structure further comprises a second open-circuit stub and a tenth microstrip line, the second open-circuit stub is connected between the output end and the third parallel line through the tenth microstrip line.

2. The topology of claim 1, wherein, The first parallel line comprises a first transmission line and a second transmission line arranged in parallel, the second parallel line comprises a third transmission line and a fourth transmission line arranged in parallel, and the third parallel line comprises a fifth transmission line and a sixth transmission line arranged in parallel; One end of the first transmission line is connected to the input end and one end of the first microstrip line; One end of the second transmission line is connected to one end of the second microstrip line, one end of the sixth microstrip line and one end of the third transmission line; One end of the fourth transmission line is connected to one end of the fifth microstrip line, one end of the ninth microstrip line and one end of the fifth transmission line; One end of the sixth transmission line is connected to one end of the tenth microstrip line and the output end; The other end of the first transmission line, the other end of the second transmission line, the other end of the third transmission line, the other end of the fourth transmission line, the other end of the fifth transmission line and the other end of the sixth transmission line are open circuits.

3. The topology of claim 1, wherein, The first parallel line, the second parallel line, the third parallel line, the first microstrip line, the third microstrip line, the fourth microstrip line, the seventh microstrip line, the eighth microstrip line and the tenth microstrip line are arranged in parallel.

4. The topology of claim 1, wherein, The first parallel line, the second parallel line, the third parallel line, the first microstrip line, the third microstrip line, the fourth microstrip line, the seventh microstrip line, the eighth microstrip line and the tenth microstrip line are perpendicular to the second microstrip line, the fifth microstrip line, the sixth microstrip line, the ninth microstrip line, the first open-circuit stub, the second open-circuit stub, the first short-circuit stub and the second short-circuit stub.

5. The topology of 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; based on the bandpass filter of the topology structure, 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 bandpass filter.

6. The topology of claim 1, wherein, The electrical length of the first microstrip line and the electrical length of the tenth microstrip line are equal, and the electrical length of the first open-circuit stub is equal to the electrical length of the second open-circuit stub. The sum of the electrical length of the first microstrip line and the electrical length of the first open-circuit stub is the quarter wavelength corresponding to the notch center frequency.

7. The topology of claim 1, wherein, The electrical length of the second microstrip line is equal to the electrical length of the ninth microstrip line. The electrical length of the third microstrip line is equal to the electrical length of the eighth microstrip line. The electrical length of the fourth microstrip line is equal to the electrical length of the seventh microstrip line. The electrical length of the fifth microstrip line is equal to the electrical length of the sixth microstrip line. The electrical length of the first short-circuit stub is equal to the electrical length of the second short-circuit stub. The sum of the electrical length of the second microstrip line and the electrical length of the third microstrip line is equal to the sum of the electrical length of the fourth microstrip line and the electrical length of the fifth microstrip line. Based on the bandpass filter of the topology structure, 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 first short-circuit stub is greater than the corresponding quarter wavelength at the center frequency of the bandpass filter.

8. The topology of claim 1, wherein, 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 microstrip line, the characteristic impedance of the tenth microstrip line, the characteristic impedance of the first open-circuit stub and the characteristic impedance of the second open-circuit stub are equal. The characteristic impedance of the first short-circuit stub is equal to the characteristic impedance of the second short-circuit stub. The characteristic impedance of the second microstrip line, the characteristic impedance of the third microstrip line, the characteristic impedance of the fourth microstrip line, the characteristic impedance of the fifth microstrip line, the characteristic impedance of the sixth microstrip line, the characteristic impedance of the seventh microstrip line, the characteristic impedance of the eighth microstrip line and the characteristic impedance of the ninth microstrip line are equal.

9. A bandpass filter, characterized by, Obtained by the topology structure as claimed in any one of claims 1 to 8.

10. A communication device comprising the bandpass filter as claimed in claim 9.

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