Topological structure, filter and communication equipment
By designing a rotationally symmetric topology including a first parallel line, an input terminal, an output terminal, a microstrip line, and short-circuit stubs, the miniaturization problem of bandpass filters at high frequencies was solved, achieving filter performance with ultra-wide bandwidth and high isolation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2026-03-06
AI Technical Summary
Existing bandpass filters face significant challenges in the high-frequency band due to parasitic effects, material losses, and manufacturing errors, making miniaturization difficult.
A rotationally symmetric topology is formed by adopting a topology including a first parallel line, an input terminal, an output terminal, a first microstrip line, a second microstrip line, a first short-circuit stub, and a second short-circuit stub. By utilizing the characteristic impedance design of odd-mode and even-mode, the positions of transmission poles and zeros are ensured, thereby achieving an ultra-wide operating bandwidth and high isolation.
It achieves ultra-wide operating bandwidth, good insertion loss flatness in the passband, and excellent selectivity in the stopband, while reducing power consumption and improving the space utilization of the filter.
Smart Images
Figure CN223978073U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of filter technology, and in particular to a topology, filter, and communication device. Background Technology
[0002] As a core component in radio frequency and microwave circuits, the topology design of bandpass filters directly affects the signal processing performance of communication systems, radar, satellite communications, and other fields. Since the rise of radio technology in the early 20th century, the topology of bandpass filters has evolved from classical resonance theory to modern integrated design, gradually forming various technical routes to meet the requirements of different frequency bands, bandwidths, and performance indicators.
[0003] Currently, the core challenge in bandpass filter topology design lies in balancing performance, size, and cost. At high frequencies, parasitic effects, material losses, and process errors are having an increasingly significant impact, while the demand for miniaturization is driving research into three-dimensional integration (such as LTCC and IPD processes) and novel topologies (such as chip-scale resonators). Utility Model Content
[0004] This application provides a topology, filter, and communication device that can at least partially solve the current urgent problem of filter miniaturization.
[0005] To solve the above-mentioned technical problems, this application adopts the following technical solution: providing a topology structure applied to a filter. The topology structure includes a first parallel line, an input terminal, an output terminal, a first microstrip line, a second microstrip line, a first short-circuit stub, and a second short-circuit stub. The input terminal and the output terminal are located on opposite sides of the first parallel line. The first parallel line includes a first transmission line and a second transmission line arranged in parallel. The input terminal is connected to one end of the first transmission line, and the output terminal is connected to one end of the second transmission line. One end of the first microstrip line is connected to the other end of the first transmission line, and one end of the second microstrip line is connected to the other end of the second transmission line. One end of the first short-circuit stub is connected to the other end of the first microstrip line, and the other end of the first short-circuit stub is grounded. One end of the second short-circuit stub is connected to the other end of the second microstrip line, and the other end of the second short-circuit stub is grounded.
[0006] Optionally, any two of the first transmission line, the second transmission line, the first short-circuit stub, and the second short-circuit stub can be parallel to each other.
[0007] Optionally, the first microstrip line is perpendicular to the first transmission line, the second microstrip line is perpendicular to the second transmission line, and the first microstrip line is parallel to the second microstrip line.
[0008] Optionally, the first transmission line and the second transmission line are parallel to each other along a first direction, and the input terminal and the output terminal are arranged opposite each other along a second direction, wherein the first direction and the second direction are perpendicular.
[0009] Optionally, the electrical lengths of the first transmission line, the second transmission line, the first microstrip line, the second microstrip line, the first short-circuit stub, and the second short-circuit stub are all quarter wavelengths corresponding to the center frequency of the bandpass filter.
[0010] Optionally, the odd-mode characteristic impedance of the first parallel line composed of the first transmission line and the second transmission line is Zoo, and the even-mode characteristic impedance is Zoe; the characteristic impedances of the first microstrip line, the second microstrip line, the first short-circuit stub, and the second short-circuit stub are equal and all are Z1.
[0011] Optionally, when the topology is in odd-mode form, the electrical length of the odd-mode transmission line of the first parallel line is a quarter wavelength corresponding to the center frequency of the bandpass filter, and the characteristic impedance is Zoo.
[0012] Optionally, when the topology is in even-mode form, the electrical length of the even-mode transmission line of the first parallel line is a quarter wavelength corresponding to the center frequency of the bandpass filter, and the characteristic impedance of the even-mode transmission line is Zoe.
[0013] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a filter that includes the above-mentioned topology.
[0014] To solve the above-mentioned technical problems, another technical solution adopted in this application is: a communication device is also provided, including the above-mentioned topology or the above-mentioned filter.
[0015] The beneficial effects of this application embodiment are as follows: Unlike existing technologies, this application embodiment provides a topology structure applied to a filter. The topology structure includes a first parallel line, an input terminal, an output terminal, a first microstrip line, a second microstrip line, a first short-circuit stub, and a second short-circuit stub. The input terminal and the output terminal are located on opposite sides of the first parallel line. The first parallel line includes a first transmission line and a second transmission line arranged in parallel. The input terminal is connected to one end of the first transmission line, and the output terminal is connected to one end of the second transmission line. One end of the first microstrip line is connected to the other end of the first transmission line, and one end of the second microstrip line is connected to the other end of the second transmission line. One end of the first short-circuit stub is connected to the other end of the first microstrip line, and the other end of the first short-circuit stub is grounded. One end of the second short-circuit stub is connected to the other end of the second microstrip line, and the other end of the second short-circuit stub is grounded. Through the above structure, a rotationally symmetric topology is formed, achieving an ultra-wide operating bandwidth, two transmission poles in the passband ensuring good insertion loss flatness, and four transmission zeros in the stopband providing excellent selectivity and isolation, thus constituting the filter of this application. 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 one embodiment of this application;
[0018] Figure 2 This is a schematic diagram of the odd-mode form of the topology provided in one embodiment of this application;
[0019] Figure 3 This is a schematic diagram of the even-mode form of the topology provided in one embodiment of this application;
[0020] Figure 4 This is a schematic diagram of the layout of the topology provided in one embodiment of this application;
[0021] Figure 5 This is the S-parameter simulation result of the filter provided in one embodiment of this application.
[0022] The attached figures are labeled as follows:
[0023]
[0024] Detailed Implementation
[0025] To facilitate understanding of this application, 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.
[0026] 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 application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.
[0027] Please see Figure 1 Topology 100 is applied to a filter. Topology 100 includes a first parallel line 20, an input terminal 10, an output terminal 50, a first microstrip line 30, a second microstrip line 31, a first short-circuit stub 41, and a second short-circuit stub 40. Input terminal 10 and output terminal 50 are located on opposite sides of the first parallel line 20. The first parallel line 20 includes a first transmission line 201 and a second transmission line 202 arranged in parallel. Input terminal 10 is connected to one end of the first transmission line 201, and output terminal 50 is connected to one end of the second transmission line 202. One end of the first microstrip line 30 is connected to the other end of the first transmission line 201, and one end of the second microstrip line 31 is connected to the other end of the second transmission line 202. One end of the first short-circuit stub 41 is connected to the other end of the first microstrip line 30, and the other end of the first short-circuit stub 41 is grounded. One end of the second short-circuit stub 40 is connected to the other end of the second microstrip line 31, and the other end of the second short-circuit stub 40 is grounded. The above structure forms a rotationally symmetric topology 100, which achieves an ultra-wide operating bandwidth, two transmission poles in the passband to ensure good insertion loss flatness, and four transmission zeros in the stopband to provide excellent selectivity and isolation, and constitutes the filter in this application.
[0028] In some embodiments, please refer to Figure 1The transmission lines 201, 202, 41, and 40 are arranged in parallel pairs. This parallel arrangement effectively expands the bandwidth of the topology 100, improves group delay response, enhances fault tolerance and redundancy, and reduces power consumption. Parallel transmission lines effectively guide the electromagnetic field, causing it to propagate along the transmission line direction, reducing scattering and loss of the electromagnetic field in space. They can also form different circuit elements, such as resonators, transmission lines, and couplers, to achieve the filtering function of a filter. Furthermore, vertically arranged transmission lines effectively separate different circuit regions, preventing mutual interference between electromagnetic fields and improving the isolation of the filter.
[0029] In some embodiments, please refer to Figure 1 The first microstrip line 30 is perpendicular to the first transmission line 201, and the second microstrip line 31 is perpendicular to the second transmission line 202. The first microstrip line 30 and the second microstrip line 31 are parallel. That is, in the above structure, the first microstrip line 30 is perpendicular to the first transmission line 201, and the second microstrip line 31 is perpendicular to the second transmission line 202, which can effectively reduce electronic coupling and crosstalk, improve impedance matching, and optimize the spatial layout of the topology 100.
[0030] In some embodiments, please refer to Figure 1 The first transmission line 201 and the second transmission line 202 are parallel to each other along a first direction, and the input terminal 10 and the output terminal 50 are positioned opposite each other along a second direction. The first direction and the second direction are perpendicular. This structure further optimizes the space utilization of the topology 100 and suppresses coupling.
[0031] In some embodiments, please refer to Figures 2 to 4 The electrical lengths of the first transmission line 201, the second transmission line 202, the first microstrip line 30, the second microstrip line 31, the first short-circuit stub 41, and the second short-circuit stub 40 are all one-quarter wavelengths corresponding to the center frequency of the bandpass filter. When the electrical lengths of the first transmission line 201 and the second transmission line 202 are equal to one-quarter wavelengths at a specific frequency, the transmission line exhibits resonant characteristics. That is, at this frequency, the input impedance and output impedance of the transmission line are both purely resistive and of equal magnitude. Utilizing this resonant characteristic, a resonator can be constructed to realize the filtering function of the filter in this application, thereby improving the transmission efficiency of the filter.
[0032] In some embodiments, please refer to Figures 2 to 4The first parallel line 20, composed of the first transmission line 201 and the second transmission line 202, has an odd-mode characteristic impedance of Zoo and an even-mode characteristic impedance of Zoe. The characteristic impedances of the first microstrip line 30, the second microstrip line 31, the first short-circuit stub 41, and the second short-circuit stub 40 are equal and all have Z1.
[0033] Further, please refer to Figure 2 When the topology 100 is in odd-mode form, the electrical length of the odd-mode transmission line of the first parallel line 20 is one-quarter wavelength corresponding to the center frequency of the bandpass filter, and its characteristic impedance is Zoo. That is, since the topology 100 can be equivalently represented as a symmetrical structure, its transmission poles can be obtained using even-odd mode analysis. The odd-mode form of the topology 100 is as follows: Figure 2 As shown, the electrical length of the odd-mode transmission line is one-quarter of the wavelength corresponding to the center frequency of the bandpass filter, and the characteristic impedance of the odd-mode transmission line is Zoo. When Y ino When f = ∞, it can be concluded that the topology 100 has two transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the two odd-mode transmission poles are as follows:
[0034]
[0035] Further, please refer to Figure 3 When the topology 100 is in even-mode form, the electrical length of the even-mode transmission line of the first parallel line 20 is one-quarter wavelength corresponding to the center frequency of the bandpass filter, and the characteristic impedance of the even-mode transmission line is Zoe. When Y ine When f = ∞, it can be concluded that the topology 100 has two even-mode transmission poles. When f0 is the center frequency of the bandpass filter, the frequencies corresponding to the two even-mode transmission poles are as follows:
[0036]
[0037] For this topology 100, its transmission zero point can be calculated using the following formula:
[0038]
[0039] Calculations show that topology 100 has four transmission zeros, and the frequencies corresponding to the four transmission zeros are as follows:
[0040] f z1 =0
[0041]
[0042] f z4 =2f0
[0043] From the above analysis, it can be seen that the filter based on this topology 100 has two odd-mode transmission poles, two even-mode transmission poles, and four transmission zeros. When the coupling between the parallel lines is very weak and the characteristic impedance of the short-circuited stub is less than the odd-mode and even-mode characteristic impedances of the parallel lines, i.e., Z1... <Z oo ≈Z oe The relative positions of the transmission zeros and poles, i.e., f z1 <f2<f op1 ≈f ep1 <fe p2 ≈f op2 <f3<f z4 The following will not change. Therefore, based on this topology 100, a bandpass filter can be designed with two transmission poles in the passband to ensure its flatness in the band, and four transmission zeros in the stopband to ensure high isolation and a wide stopband.
[0044] To verify the above theory, a broadband bandpass filter example based on this topology 100 was designed on a circuit board with a dielectric constant of 3.38, a dielectric loss of 0.0022, and a thickness of 0.813 mm. The circuit board measures 13.0 mm * 10.2 mm. Figure 4 As shown. Its dimensional parameters are set as follows: l P =9.2mm,s P =0.1mm,w P =0.2mm, l1=3.9mm, l2=6.1mm, w1=0.4mm.
[0045] Simulation results of the broadband bandpass filter are as follows: Figure 5 As shown in the figure, the impedance bandwidth with a reflection coefficient less than -10dB ranges from 4.15 to 5.87 GHz, the passband center frequency is 5.01 GHz, the absolute passband bandwidth is 1.72 GHz, and the relative passband bandwidth is 34.3%. Furthermore, within the passband, there are two transmission poles located at 4.44 GHz and 5.6 GHz, which ensure the flatness of the passband filter. In the stopband, there are four transmission zeros located at 0, 1.72, 8.13, and 10.44 GHz. The lower stopband bandwidth with isolation greater than 10dB ranges from 0 to 2.23 GHz, and the upper stopband bandwidth with isolation greater than 10dB ranges from 7.11 to 12 GHz, exhibiting wide stopband characteristics.
[0046] This application aims to provide a topology 100 applied to a filter. The topology 100 includes a first parallel line 20, an input terminal 10, an output terminal 50, a first microstrip line 30, a second microstrip line 31, a first short-circuit stub 41, and a second short-circuit stub 40. The input terminal 10 and the output terminal 50 are located on opposite sides of the first parallel line 20. The first parallel line 20 includes a first transmission line 201 and a second transmission line 202 arranged in parallel. The input terminal 10 is connected to one end of the first transmission line 201, and the output terminal 50 is connected to one end of the second transmission line 202. One end of the first microstrip line 30 is connected to the other end of the first transmission line 201, and one end of the second microstrip line 31 is connected to the other end of the second transmission line 202. One end of the first short-circuit stub 41 is connected to the other end of the first microstrip line 30, and the other end of the first short-circuit stub 41 is grounded. One end of the second short-circuit stub 40 is connected to the other end of the second microstrip line 31, and the other end of the second short-circuit stub 40 is grounded. The above structure forms a rotationally symmetric topology 100, which achieves an ultra-wide operating bandwidth, two transmission poles in the passband to ensure good insertion loss flatness, and four transmission zeros in the stopband to provide excellent selectivity and isolation, and constitutes the filter in this application.
[0047] Based on the same inventive concept, this application also provides a filter, including a topology 100, which has the same function and structure as the topology 100 described above, and will not be described in detail here.
[0048] Based on the same inventive concept, this application also provides a communication device, including a topology 100 or a filter, which has the same function and structure as the topology 100 or filter described above, and will not be described in detail here.
[0049] It should be noted that while preferred embodiments of this application are provided in the specification and accompanying drawings, this application 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 application; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this application. 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 application's 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 applied to a filter, characterized in that, The topology structure comprises: a first parallel line, an input end and an output end, the input end and the output end being located on two sides of the first parallel line, the first parallel line comprising a first transmission line and a second transmission line arranged in parallel, the input end being connected to one end of the first transmission line, and the output end being connected to one end of the second transmission line; a first microstrip line and a second microstrip line, one end of the first microstrip line being connected to the other end of the first transmission line, and one end of the second microstrip line being connected to the other end of the second transmission line; and a first short-circuit stub and a second short-circuit stub, one end of the first short-circuit stub being connected to the other end of the first microstrip line, and the other end of the first short-circuit stub being grounded, one end of the second short-circuit stub being connected to the other end of the second microstrip line, and the other end of the second short-circuit stub being grounded.
2. The topology of claim 1, wherein, Any two of the first transmission line, the second transmission line, the first short-circuit stub and the second short-circuit stub are parallel to each other.
3. The topology of claim 2, wherein, The first microstrip line is perpendicular to the first transmission line, and the second microstrip line is perpendicular to the second transmission line, and the first microstrip line is parallel to the second microstrip line.
4. The topology of claim 1, wherein, The first transmission line and the second transmission line are parallel to each other along a first direction, and the input end and the output end are oppositely arranged along a second direction, and the first direction and the second direction are perpendicular to each other.
5. The topology of claim 1, wherein, The electrical length of the first transmission line, the electrical length of the second transmission line, the electrical length of the first microstrip line, the electrical length of the second microstrip line, the electrical length of the first short-circuit stub and the electrical length of the second short-circuit stub are all one-quarter of the wavelength corresponding to the center frequency of the band-pass filter.
6. The topology of claim 2, wherein, The odd-mode characteristic impedance of the first parallel line composed of the first transmission line and the second transmission line is Zoo, and the even-mode characteristic impedance is Zoe; the characteristic impedances of the first microstrip line, the second microstrip line, the first short-circuit stub and the second short-circuit stub are equal, and are all Z1.
7. The topology of claim 4, wherein, When the topology structure is in odd-mode form, the electrical length of the odd-mode transmission line of the first parallel line is one-quarter of the wavelength corresponding to the center frequency of the band-pass filter, and the characteristic impedance is Zoo.
8. The topology of claim 4, wherein, When the topology structure is in even-mode form, the electrical length of the even-mode transmission line of the first parallel line is one-quarter of the wavelength corresponding to the center frequency of the band-pass filter, and the characteristic impedance of the even-mode transmission line is Zoe.
9. A filter, characterized by The topology structure comprises the topology structure according to any one of claims 1-8.
10. A communication device, characterized by The topology structure comprises the topology structure according to any one of claims 1-8. Or, the filter comprises the topology structure according to claim 9.