Filters and circuit elements

Abstract

A filter is disposed on a circuit board and includes a first coupling line, a second coupling line, a closed line, at least one ground plane, and at least one ground via. The closed line includes a first coupling portion and a second coupling portion. The first coupling line, the second coupling line, and the closed line are located on a conductive layer of the circuit board. The first coupling line and the second coupling line are parallel to the first coupling portion and the second coupling portion, respectively. The first coupling line and the second coupling line couple the closed line. The at least one ground plane is located on another conductive layer of the circuit board. The at least one ground via is connected between the closed line and the at least one ground plane. Thus, the operating bandwidth is expanded. The disclosure also relates to a circuit element.

Description

Technical Field

[0001] This disclosure relates to a filter and circuit element, and more particularly to a filter and circuit element disposed on a circuit board. Background Technology

[0002] Driven by humanity's pursuit of a more convenient life, diverse wireless communication systems and radio frequency technologies have been developed. For example, the recent rise of 5G millimeter-wave (mmWave) technology has led to an increasing number of consumer electronics products incorporating this technology, with terminal products constantly being updated. This means that the development and manufacturing costs and design complexity of wireless communication modules and their components will correspondingly increase. For instance, 5G millimeter-wave communication modules typically require a very small size; therefore, some radio frequency circuit elements that occupy significant volume or area in existing technologies (such as filters) will not be suitable for 5G millimeter-wave communication modules.

[0003] In view of this, how to reduce the size, cost and design complexity of circuit components such as filters in wireless communication modules, while meeting the radio frequency characteristics requirements of wireless communication systems, and further making the products more competitive in the market, has become a topic of concern in the market. Summary of the Invention

[0004] This disclosure provides a filter and circuit element disposed on a circuit board and including a first coupling line, a second coupling line, a closed line, at least one ground plane, and at least one ground via. The closed line is coupled through the first coupling line and the second coupling line, and the at least one ground via is connected between the closed line and the at least one ground plane to reduce cost and volume. By using the ground via to generate a ground path, a low-frequency mode is generated at the adjacent location of the resonant frequency of the closed line, thereby achieving a dual-mode effect and expanding the operating bandwidth.

[0005] According to one embodiment of this disclosure, a filter is provided, disposed on a circuit board and including a first coupling line, a second coupling line, a closed line, at least one ground plane, and at least one ground via. The first coupling line is connected to a first feed point, and the second coupling line is connected to a second feed point. The closed line includes a first coupling portion and a second coupling portion. The first coupling line, the second coupling line, and the closed line are all located on a conductive layer of the circuit board. The first coupling line and the second coupling line are parallel to the first coupling portion and the second coupling portion, respectively, and are coupled to the closed line. The at least one ground plane is located on another conductive layer of the circuit board and serves as a reference ground for the first coupling line, the second coupling line, and the closed line. The at least one ground via connects the closed line and the at least one ground plane. The closed line further includes a first annular region and a second annular region. The first coupling portion and the second coupling portion are located in the first annular region and the second annular region, respectively. The first annular region and the second annular region are connected at an intersection, and the at least one ground via connects to the intersection.

[0006] According to another embodiment of this disclosure, a circuit element is provided, disposed on a circuit board and including a first coupling line, a second coupling line, a closed line, at least one ground plane, and at least one ground via. The first coupling line extends of equal length in two directions from a first feed point, and the second coupling line extends of equal length in two directions from a second feed point. The closed line includes a first coupling portion and a second coupling portion. The first coupling line, the second coupling line, and the closed line are all located on a conductive layer of the circuit board. The first coupling line and the second coupling line are parallel to the first coupling portion and the second coupling portion, respectively, and the first coupling line and the second coupling line couple to the closed line. The at least one ground plane is located on another conductive layer of the circuit board and serves as a reference ground for the first coupling line, the second coupling line, and the closed line. The at least one ground via connects the closed line and the at least one ground plane. The at least one ground via divides the closed line into a first annular region and a second annular region with equal paths. The first coupling portion and the second coupling portion are located in the first annular region and the second annular region, respectively. The first annular region and the second annular region are connected at an intersection, and the at least one ground via connects to the intersection. Attached Figure Description

[0007] Figure 1A A perspective view of the filter according to the first embodiment of the present disclosure is shown;

[0008] Figure 1B Draw Figure 1A Top view of the conductive layer of the filter;

[0009] Figure 1C Draw Figure 1A A schematic diagram of the S-parameters of the filter.

[0010] Figure 1D Draw another filter and Figure 1A A schematic diagram of the surface current density of a medium-density filter;

[0011] Figure 2A A perspective view of the filter according to the second embodiment of this disclosure is shown;

[0012] Figure 2B Draw Figure 2A Top view of the conductive layer of the filter;

[0013] Figure 2C Draw Figure 2A A schematic diagram of the S-parameters of the filter.

[0014] Figure 3A A perspective view of the filter according to the third embodiment of this disclosure is shown;

[0015] Figure 3B Draw Figure 3A A top view of the conductive layer of the filter; and

[0016] Figure 3C Draw Figure 3A A schematic diagram of the S-parameters of the filter.

[0017] The reference numerals in the attached figures are explained as follows:

[0018] 100, 200, 300: Filters

[0019] 101, 102, 103, 201, 202, 203, 301, 302, 303: Conductive layers

[0020] 108, 208, 308: Circuit Boards

[0021] 110, 210, 310: First feed line

[0022] 119, 219, 319: First feed point

[0023] 120, 220, 320: First coupling line

[0024] 130, 230, 330: Closed lines

[0025] 131, 231, 331: First coupling part

[0026] 132, 232, 332: Second coupling section

[0027] 141, 241: First ring region

[0028] 142, 242: Second ring area

[0029] 143, 243: Meeting Point

[0030] 160, 260, 360: Second coupling line

[0031] 170, 270, 370: Second feed line

[0032] 179, 279, 379: Second feed point

[0033] 180, 188, 189, 280, 288, 289, 380, 383, 388: Grounding vias

[0034] 213, 273: Conductors

[0035] 341: First line segment area

[0036] 342: Second line segment area

[0037] 390, 393: Side quests

[0038] d9: Path length

[0039] g23: Spacing

[0040] m1, m2: Marker points

[0041] p: Horizontal axis

[0042] q: Vertical axis

[0043] w2, w3: Width Detailed Implementation

[0044] Figure 1A A perspective view of the filter 100 according to the first embodiment of the present disclosure is shown. Figure 1B Draw Figure 1A A top view of the conductive layer 102 of the intermediate filter 100. Please refer to... Figure 1A and Figure 1B According to the first embodiment of this disclosure, the circuit element is specifically a filter 100. The filter 100 is disposed on a circuit board 108 and includes a first coupling line 120, a second coupling line 160, a closed line 130, at least one ground plane (not otherwise labeled), and a ground via 180. The circuit board 108 is specifically disposed on... Figure 1A The middle layer contains conductive layers 101, 102, and 103 in sequence from top to bottom.

[0045] The first coupling line 120 connects to the first feed point 119, and the second coupling line 160 connects to the second feed point 179. The closed line 130 includes a first coupling portion 131 and a second coupling portion 132. The first coupling line 120, the second coupling line 160, and the closed line 130 are all located on the conductive layer 102 of the circuit board 108. The first coupling line 120 and the second coupling line 160 are parallel to the first coupling portion 131 and the second coupling portion 132, respectively (i.e., maintaining the same distance from the first coupling portion 131 and the second coupling portion 132, respectively), and the first coupling line 120 and the second coupling line 160 are coupled to the closed line 130. At least one ground plane is located on the conductive layers 101 and 103 of the circuit board 108. The ground plane located on the conductive layers 101 and 103 serves as the reference ground for the first coupling line 120, the second coupling line 160, and the closed line 130. A ground via 180 connects the closed line 130 and the ground plane located on the conductive layers 101 and 103. This allows the filter 100 to be designed as a planar bandpass filter (BPF) on circuit board 108 without the need for discrete components, thus reducing cost and size. Furthermore, by using the grounding via 180 to create a grounding path, the resonant frequency of the closed line 130 (e.g., Figure 1C Low-frequency modes (such as those corresponding to the frequency of 39.70 GHz at the marked point m2) are generated at locations adjacent to the point m2. Figure 1CThe frequency corresponding to the marked point m1 is 37.40GHz, thereby achieving a dual-mode effect to expand the operating (application) bandwidth.

[0046] Furthermore, each of the first coupling line 120, the second coupling line 160, and the closed line 130 of the filter 100 is specifically a stripline. It should be understood that the transmission line types of the first feed line, second feed line, first coupling line, second coupling line, and closed line of the filter according to this disclosure can also be microstrip lines, and are not limited to those disclosed in the first to third embodiments. Moreover, the circuit elements in other embodiments according to this disclosure can specifically be filters or circuit elements containing filtering characteristics, such as diplexers. The shape and size of the circuit board are not limited to the figures in this disclosure. The circuit board can be a printed circuit board, a flexible circuit board, or a circuit substrate made of other dielectric materials, and is not limited thereto. Additionally, the "connection" described in this disclosure refers to a physical connection between two elements, whether direct or indirect, while the "coupled" described in this disclosure refers to two elements that are separated from each other without a physical connection, and the electric field energy generated by the current in one element excites the electric field energy of the other element.

[0047] Specifically, the closed line 130 includes a first annular region 141 and a second annular region 142, both of which are closed annular. The first coupling portion 131 and the second coupling portion 132 are located in the first annular region 141 and the second annular region 142, respectively. The first annular region 141 and the second annular region 142 are connected to the intersection portion 143, and the grounding via 180 is connected to the intersection portion 143. Thus, the filter 100 has a grounding via 180 at the intersection portion 143 at the center of the structure, which is grounded to the upper and lower conductive layers 101 and 103. By using the grounding via 180 to create a grounding path, the filter 100 generates a low-frequency mode adjacent to the resonant frequency of the original annular structure of the closed line 130, thereby achieving a dual-mode effect and expanding the operating bandwidth. Furthermore, according to the present disclosure, the intersection portion of the filter can also be specifically provided with two or more grounding vias to further expand the operating bandwidth while meeting the single-passband dual-mode 3dB bandwidth requirement.

[0048] The closed line 130 is in the shape of a Chinese character "日" (specifically, an 8-shaped), and the path length of the first annular region 141 is equal to the path length of the second annular region 142. Here, the path length described in this disclosure refers to its central path length. Further, a grounding via 180 divides the closed line 130 into two regions with equal paths (i.e., the first annular region 141 and the second annular region 142), and the first coupling portion 131 and the second coupling portion 132 are respectively located in the first annular region 141 and the second annular region 142. Thereby, the filter 100 has a simple resonance structure, which is beneficial to reducing the design complexity, and can achieve a dual-mode effect without connecting multiple structures in series.

[0049] The first coupling line 120 extends equally in two directions (i.e., Figure 1B the upper and lower directions) from the first feeding point 119, and the second coupling line 160 extends equally in two directions from the second feeding point 179. That is, each of the first coupling line 120 and the second coupling line 160 forms a structure of a coupling arm or a feeding arm. Thereby, an appropriate feeding method can effectively excite the dual-mode resonance of the filter 100 to avoid the complex structure, large volume, and high cost of connecting multiple structures in series or using discrete components.

[0050] The path length of the first coupling line 120 is equal to the path length of the second coupling line 160, and the ratio of the path length of the closed line 130 to the path length of the first coupling line 120 can be between 2.2 and 20. Furthermore, the ratio can be between 2.5 and 4.5. Thereby, the filter 100 can reduce the structure volume because it does not use discrete components, so as to be suitable for millimeter-wave wireless communication modules. In the first embodiment, the path length of the closed line 130 is 4168 um (Micrometer), and the path length of the first coupling line 120 is 1164 um, so the ratio is 3.58.

[0051] The filter 100 may further include a first feed line 110 and a second feed line 170, both located in the conductive layer 102. Each of the first feed line 110, the second feed line 170, the first coupling portion 131, and the second coupling portion 132 may be a 50-ohm stripline. A first feed point 119 is connected between the first feed line 110 and the first coupling line 120, and a second feed point 179 is connected between the second feed line 170 and the second coupling line 160. Both the first feed line 110 and the second feed line 170 are arranged along a virtual transverse axis (or transverse plane) p. This planar design of the filter 100 helps to reduce the structural volume. Furthermore, the first and second feed lines of the filter according to this disclosure may also be connected to the first and second coupling lines respectively via vias and located in different conductive layers. Furthermore, multiple grounding vias 189 can be provided on the inner side of each of the first annular region 141 and the second annular region 142, and multiple grounding vias 188 can also be provided along both sides or around the filter 100, and the arrangement of the grounding vias 188 and 189 is not limited to the following: Figure 1A and Figure 1B To limit the impact of interference from nearby circuits or electromagnetic waves on the characteristics of filter 100, and to provide grounding integrity.

[0052] Filter 100 is specifically symmetrical about both the horizontal axis p and the virtual vertical axis (or vertical plane) q, with the horizontal axis p and the vertical axis q being perpendicular to each other. This helps to reduce design complexity.

[0053] Please refer to Figure 1B A spacing g23 is provided between the first coupling line 120 and the first coupling portion 131. The ratio of the width w2 of the first coupling line 120 to the width w3 of the closed line 130 can be between 0.2 and 5, and the ratio of the width w2 of the first coupling line 120 to the spacing g23 can be between 0.25 and 3. Furthermore, the ratio of the width w2 of the first coupling line 120 to the width w3 of the closed line 130 can be between 0.3 and 2. In addition, the ratio of the width w2 of the first coupling line 120 to the spacing g23 can be between 0.4 and 2.25. This allows for the effective implementation of a dual-mode filter 100 to meet the wide operating bandwidth requirements of 5G millimeter-wave communication modules. In the first embodiment, the ratio of the width w2 (30um) of the first coupling line 120 to the width w3 (62um) of the closed line 130 is 0.48, and the ratio of the width w2 of the first coupling line 120 to the spacing g23 (30um) is 1.

[0054] Figure 1C Draw Figure 1AThe diagram shows the S-parameters of the intermediate filter 100. The first and second measurement terminals used to measure the S-parameters in the diagram can be respectively located at the edges of the first feed line 110 and the second feed line 170 on the circuit board 108. Please refer to... Figure 1C The filter 100 has a 3dB bandwidth defined by parameter S21, ranging from 37.00GHz to 40.25GHz. Therefore, it is suitable for the current 5G millimeter-wave frequency band. Within the 3dB bandwidth, parameters S11 and S22 are both less than -10dB and exhibit dual-mode operation. The indicative point m1 of parameter S11 is 37.40GHz and -16.34dB, and the indicative point m2 of parameter S11 is 39.70GHz and -17.48dB. It can be seen that filter 100 has two resonant frequencies, 37.40GHz and 39.70GHz. The frequencies corresponding to the extreme values ​​of S parameters within the 3dB bandwidth of filter 100 can be defined as resonant frequencies.

[0055] The ratio of the sum of the path lengths of the first ring region 141 and the second ring region 142 (i.e., the path length of the figure-eight closed line 130 including the intersection 143) to the effective wavelength of the resonant frequencies 37.40 GHz and 39.70 GHz of the filter 100 on the circuit board 108 can be between 0.8 and 1.1. Furthermore, the ratio can be between 0.9 and 1.05. Thus, when the wavelength of the input signal matches the loop path length of the closed line 130, the higher of the two resonant frequencies in the dual-mode is generated, and a low-frequency mode is generated adjacent to the higher-frequency resonant frequency by using the grounding via 180 to create a grounding path, thereby achieving a dual-mode effect. In the first embodiment, the path length of the closed line 130 is 4168um, and the effective wavelengths of the two resonant frequencies of the filter 100, 37.40GHz and 39.70GHz, on the circuit board 108 are approximately 4424um and 4168um, respectively, so their ratios are 0.94 and 1, respectively.

[0056] Figure 1D Draw another filter and Figure 1A A schematic diagram of the surface current density of the filter 100, wherein... Figure 1D (a) The surface current density of another filter (not shown in the figure) without a grounding via 180 is illustrated. Figure 1D (b) and (c) illustrate the surface current density of the filter 100 according to this disclosure, and Figure 1D The edge lines of the intermediate filter 100 are only for illustrative purposes and are not used to represent the magnitude of the surface current density. Please refer to... Figures 1B to 1D When the other filter differs from filter 100 in that it does not have a grounding via 180, its surface current density at a frequency of 37.4 GHz is as follows: Figure 1DAs shown in (a), the excitation current on the closed line is very small, i.e., no resonance occurs. Conversely, the surface current densities of the filter 100 according to this disclosure at 37.4 GHz and 39.7 GHz are as follows: Figure 1D As shown in (b) and (c), there is a concentrated current distribution on the closed line 130 at both the low frequency of 37.4 GHz and the high frequency of 39.7 GHz, meaning that the filter 100 generates a resonant frequency, among which... Figure 1D (b) It shows that the excitation current occurs at 37.4 GHz, which is lower than 39.7 GHz, i.e., the resonant generation of the adjacent mode at a lower frequency, and as... Figure 1C The S-parameters of the dual-mode filter are shown, thus the filter 100 is specifically suitable for current 5G millimeter-wave products and can expand the operating bandwidth. Furthermore, the first embodiment... Figure 1B In the first feed point 119, the distance between the second feed point 179 is 1686um, and the distance between the two ends of the first coupling line 120 parallel to the longitudinal axis q is 756um. Therefore, the filter 100 has sufficiently small length and width dimensions to be suitable for 5G millimeter wave products.

[0057] Figure 2A A perspective view of the filter 200 according to the second embodiment of the present disclosure is shown. Figure 2B Draw Figure 2A A top view of the conductive layer 202 of the intermediate filter 200. Please refer to... Figure 2A and Figure 2B According to the second embodiment of this disclosure, the circuit element is specifically a filter 200. The filter 200 is disposed on a circuit board 208 and includes a first coupling line 220, a second coupling line 260, a closed line 230, at least one ground plane (not otherwise labeled), and a grounding via 280. The circuit board 208 is specifically disposed on... Figure 2A The middle layer contains conductive layers 201, 202, and 203 in sequence from top to bottom.

[0058] The first coupling line 220 connects to the first feed point 219, and the second coupling line 260 connects to the second feed point 279. The closed line 230 includes a first coupling portion 231 and a second coupling portion 232. The first coupling line 220, the second coupling line 260, and the closed line 230 are all located on the conductive layer 202 of the circuit board 208 and are specifically strip lines. The first coupling line 220 and the second coupling line 260 are parallel to the first coupling portion 231 and the second coupling portion 232, respectively, and are coupled to the closed line 230. At least one ground plane is located on the conductive layers 201 and 203 of the circuit board 208. The ground plane located on the conductive layers 201 and 203 serves as the reference ground for the first coupling line 220, the second coupling line 260, and the closed line 230. A grounding via 280 connects the closed line 230 to the ground plane located on the conductive layers 201 and 203.

[0059] Specifically, the closed line 230 specifically includes a first annular region 241 and a second annular region 242, both of which are closed rings. The first coupling portion 231 and the second coupling portion 232 are respectively located in the first annular region 241 and the second annular region 242. The first annular region 241 and the second annular region 242 are connected to the intersection portion 243, and the grounding via 280 is connected to the intersection portion 243. The closed line 230 is in the shape of a Chinese character "ri" (日), specifically an 8-shaped, and the path length of the first annular region 241 is equal to the path length of the second annular region 242. Further, one grounding via 280 divides the closed line 230 into two regions with equal paths (i.e., the first annular region 241 and the second annular region 242), and the first coupling portion 231 and the second coupling portion 232 are respectively located in the first annular region 241 and the second annular region 242.

[0060] The first coupling line 220 extends equidistantly in two directions (i.e., Figure 2B the upper and lower directions in the middle) from the first feeding point 219, and the second coupling line 260 extends equidistantly in two directions from the second feeding point 279. That is, each of the first coupling line 220 and the second coupling line 26 is formed into a structure of a coupling arm or a feeding arm. The path length of the first coupling line 220 is equal to the path length of the second coupling line 260. The path length of the closed line 230 is 4085um, and the path length of the first coupling line 220 is 1463um, so the ratio is 2.79.

[0061] The filter 200 further includes a first feeding line 210, wires 213, 273, and a second feeding line 270, all of which are located in the conductive layer 202. Each of the first feeding line 210, the second feeding line 270, the first coupling portion 231, and the second coupling portion 232 is a 50-ohm strip line. The widths of the wires 213 and 273 are both 30um and the lengths are both 100um. The widths of the wires 213 and 273 are different from those of the first feeding line 210 and the second feeding line 270 and form an impedance matching unit. The first feeding line 210, the wire 213, the first feeding point 219, and the first coupling line 220 are connected in sequence, and the second feeding line 270, the wire 273, the second feeding point 279, and the second coupling line 260 are connected in sequence. The first feeding line 210 and the second feeding line 270 are both arranged along the virtual horizontal axis p. Moreover, the filter 200 is not symmetrical about the horizontal axis p, nor is it symmetrical about the virtual vertical axis q, where the horizontal axis p and the vertical axis q are perpendicular to each other. In addition, a plurality of grounding vias 中的289 are provided on the inner sides of each of the first annular region 241 and the second annular region 242, and a plurality of grounding vias 288 are also provided on both sides or around the filter 200. And the impedance matching unit of the filter according to the present disclosure can be a wire or a pattern on the circuit board.

[0062] Please refer to Figure 2BThe first coupling line 220 and the first coupling part 231 have a spacing g23. The ratio of the width w2 (30um) of the first coupling line 220 to the width w3 (62um) of the closed line 230 is 0.48, and the ratio of the width w2 of the first coupling line 220 to the spacing g23 (29um) is 1.03.

[0063] Figure 2C Draw Figure 2A The diagram shows the S-parameters of the intermediate filter 200. The first and second measurement terminals used to measure the S-parameters in the diagram can be respectively located at the edges of the first feed line 210 and the second feed line 270 on the circuit board 208. Please refer to... Figure 2C The filter 200 has a 3dB bandwidth defined by parameter S21, ranging from 36.66GHz to 40.00GHz. Within this 3dB bandwidth, parameters S11 and S22 are both less than -10dB and exhibit dual-mode operation. Specifically, the S11 parameter has a reference point m1 of 37.20GHz and a reference point m2 of 39.30GHz and a reference point m2 of 39.14GHz. Therefore, the filter 200 has two resonant frequencies: 37.20GHz and 39.30GHz. Thus, the filter 200 is specifically suitable for current 5G millimeter-wave products and can expand the operating bandwidth. Furthermore, the second embodiment... Figure 2B In the first feed point 219, the distance between the second feed point 279 is 1688um, and the distance between the two ends of the first coupling line 220 parallel to the longitudinal axis q is 756um. Therefore, the filter 200 has sufficiently small length and width dimensions to be suitable for 5G millimeter wave products.

[0064] In the second embodiment, the path length of the closed line 230 is 4085um. The effective wavelengths of the two resonant frequencies of the filter 200, 37.20GHz and 39.30GHz, on the circuit board 208 are approximately 4316um and 4085um, respectively. Therefore, the sum of the path lengths of the first annular region 241 and the second annular region 242 (i.e., the path length of the figure-eight closed line 230 including the intersection 243) is 0.95 and 1, respectively, compared to the effective wavelengths of the resonant frequencies of the filter 200, 37.20GHz and 39.30GHz, on the circuit board 208.

[0065] Figure 3A A perspective view of the filter 300 according to the third embodiment of this disclosure is shown. Figure 3B Draw Figure 3A Top view of the conductive layer 302 of the intermediate filter 300. Please refer to... Figure 3A and Figure 3BAccording to the third embodiment of this disclosure, the circuit element is specifically a filter 300. The filter 300 is disposed on a circuit board 308 and includes a first coupling line 320, a second coupling line 360, a closed line 330, at least one ground plane (not otherwise labeled), and grounding vias 380 and 383. The circuit board 308 is specifically disposed on... Figure 3A The middle layer contains conductive layers 301, 302, and 303 in sequence from top to bottom.

[0066] The first coupling line 320 connects to the first feed point 319, and the second coupling line 360 ​​connects to the second feed point 379. The closed line 330 includes a first coupling portion 331 and a second coupling portion 332. The first coupling line 320, the second coupling line 360, and the closed line 330 are all located on the conductive layer 302 of the circuit board 308 and are specifically strip lines. The first coupling line 320 and the second coupling line 360 ​​are parallel to the first coupling portion 331 and the second coupling portion 332, respectively, and are coupled to the closed line 330. At least one ground plane is located on the conductive layers 301 and 303 of the circuit board 308. The ground plane located on the conductive layers 301 and 303 serves as the reference ground for the first coupling line 320, the second coupling line 360, and the closed line 330. Grounding vias 380 and 383 connect the closed line 330 to the ground plane located on the conductive layers 301 and 303.

[0067] In detail, the closed line 330 is specifically a single ring, with two grounding vias 380 and 383. These vias 380 and 383 are located inside the closed line 330, dividing it into two equal-path regions (i.e., the first segment region 341 and the second segment region 342). The first coupling portion 331 and the second coupling portion 332 are located in the first segment region 341 and the second segment region 342, respectively. According to this disclosure, each of the first and second segment regions of the filter can be a straight line, an arc, or a curve. Therefore, the filter 300 has a simple resonant structure, which helps reduce design complexity and achieves a dual-mode effect without requiring multiple structures to be connected in series. Furthermore, by using the grounding vias 380 and 383 to generate grounding paths, the filter 300 generates low-frequency modes adjacent to the resonant frequency of the original ring structure of the closed line 330, thereby achieving a dual-mode effect and expanding the operating bandwidth.

[0068] Filter 300 specifically includes branches 390 and 393. Branch 390 connects between the closed line 330 and the grounding via 380, and branch 393 connects between the closed line 330 and the grounding via 383. The ratio of the path length of the closed line 330 to the path length d9 of each of the branches 390 and 393 is between 10 and 100. The path length of the closed line 330 does not include the path lengths of the branches 390 and 393. The path length d9 of the branch 390 (or 393) refers to the path length from the edge of the closed line 330 to the center of the grounding via 380 (or 383). Furthermore, the ratio is between 35 and 55. This allows for both the requirement of a single-passband dual-mode 3dB bandwidth and an expanded operating bandwidth. In the third embodiment, the ratio of the path length (3906um) of the closed line 330 to the path length d9 (89um) of each of the branches 390 and 393 is 43.89.

[0069] The first coupling line 320 extends from the first feed point 319 in two directions (i.e., ... Figure 3B The first coupling line 320 and the second coupling line 360 ​​extend in equal length in both directions (upper and lower). The second coupling line 360 ​​extends from the second feed point 379 in both directions, meaning that each of the first coupling line 320 and the second coupling line 360 ​​forms a coupling arm or a feed arm. The path lengths of the first coupling line 320 and the second coupling line 360 ​​are equal. The path length of the closed line 330 is 3906 μm, and the path length of the first coupling line 320 is 1163 μm, so their ratio is 3.36.

[0070] The filter 300 further includes a first feed line 310 and a second feed line 370, both located in the conductive layer 302. Each of the first feed line 310, the second feed line 370, the first coupling portion 331, and the second coupling portion 332 is a 50-ohm stripline. A first feed point 319 connects the first feed line 310 and the first coupling line 320, and a second feed point 379 connects the second feed line 370 and the second coupling line 360. Both the first feed line 310 and the second feed line 370 are arranged along a virtual horizontal axis p. Furthermore, the filter 300 is specifically symmetrical about both the horizontal axis p and the virtual vertical axis q, wherein the horizontal axis p and the vertical axis q are perpendicular to each other, i.e., the filter 300 has a balanced structure. It should be understood that the structure of the filter according to this disclosure may also be symmetrical about only one of the horizontal and vertical axes, or may not be asymmetrical. In addition, a plurality of grounding vias 388 are also provided along both sides or around the filter 300.

[0071] Please refer to Figure 3BThe first coupling line 320 and the first coupling part 331 have a spacing g23. The ratio of the width w2 (30um) of the first coupling line 320 to the width w3 (62um) of the closed line 330 is 0.48, and the ratio of the width w2 of the first coupling line 320 to the spacing g23 (30um) is 1.

[0072] Figure 3C Draw Figure 3A The diagram shows the S-parameters of the intermediate filter 300. The first and second measurement terminals used to measure the S-parameters in the diagram can be respectively located at the edges of the first feed line 310 and the second feed line 370 on the circuit board 308. Please refer to... Figure 3C The filter 300 has a 3dB bandwidth defined by parameter S21, ranging from 36.98GHz to 40.41GHz. Within this 3dB bandwidth, parameters S11 and S22 are both less than -10dB and exhibit dual-mode operation. Specifically, the S11 parameter has a reference point m1 of 37.40GHz and a reference point m2 of 39.80GHz and a reference point m2 of 39.80GHz and a reference point m2 of 39.80GHz. Therefore, the filter 300 has two resonant frequencies: 37.40GHz and 39.80GHz. Thus, the filter 300 is specifically suitable for current 5G millimeter-wave products and can expand the operating bandwidth. Furthermore, the third embodiment... Figure 3B In the first feed point 319, the distance between the second feed point 379 is 1840um, and the distance between the two ends of the first coupling line 320 parallel to the longitudinal axis q is 756um. Therefore, the filter 300 has sufficiently small length and width dimensions to be suitable for 5G millimeter wave products.

[0073] In the third embodiment, the path length of the closed line 330 is 3906um. The effective wavelengths of the two resonant frequencies of the filter 300, 37.40GHz and 39.80GHz, on the circuit board 308 are approximately 4157um and 3906um, respectively. Therefore, the sum of the path lengths of the first segment region 341 and the second segment region 342 (i.e., the path length of the closed line 330) compared to the effective wavelengths of the resonant frequencies of the filter 300, 37.40GHz and 39.80GHz, on the circuit board 308 are 0.94 and 1, respectively.

[0074] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A filter, characterized in that, It is disposed on a circuit board and includes: A first coupling line connects to a first feed point; A second coupling line connects to a second feed point; A closed line includes a first coupling portion and a second coupling portion, wherein the first coupling line, the second coupling line and the closed line are all located on a conductive layer of the circuit board, the first coupling line and the second coupling line are parallel to the first coupling portion and the second coupling portion respectively, and the first coupling line and the second coupling line are coupled to the closed line; At least one ground plane is located on another conductive layer of the circuit board, wherein the at least one ground plane is the reference ground for the first coupling line, the second coupling line and the closed line; as well as At least one grounding through hole is connected between the closed wire and the at least one grounding plane; The closed line further includes a first annular region and a second annular region. The first coupling part and the second coupling part are located in the first annular region and the second annular region, respectively. The first annular region and the second annular region are connected to a junction, and the at least one grounding through hole is connected to the junction.

2. The filter as described in claim 1, characterized in that, The closed line is figure-eight shaped, and the path length of the first ring area is equal to the path length of the second ring area.

3. The filter as described in claim 1, characterized in that, The filter has at least two resonant frequencies, and the ratio of the sum of the path lengths of the first ring region and the second ring region to the effective wavelength of each of the at least two resonant frequencies of the filter on the circuit board is between 0.8 and 1.

1.

4. The filter as described in claim 1, characterized in that, The path lengths of the first coupling line and the second coupling line are equal, and the ratio of the path length of the closed line to the path length of the first coupling line is between 2.2 and 20.

5. The filter as described in claim 1, characterized in that, It also includes: A first feed line, wherein the first feed point is connected between the first feed line and the first coupling line; and A second feed line, wherein the second feed point is connected between the second feed line and the second coupling line; Both the first feed line and the second feed line are arranged along a virtual horizontal axis.

6. The filter as described in claim 5, characterized in that, The filter is symmetrical about the horizontal axis and a virtual vertical axis, which are perpendicular to each other. The first coupling line and the first coupling portion are spaced apart. The ratio of the width of the first coupling line to the width of the closed line is between 0.2 and 5, and the ratio of the width of the first coupling line to the space is between 0.25 and 3.

7. A circuit element, characterized in that, It is disposed on a circuit board and includes: A first coupling line extends of equal length from a first feed point in two directions; A second coupling line extends at equal length in two directions from a second feed point; A closed line includes a first coupling portion and a second coupling portion, wherein the first coupling line, the second coupling line and the closed line are all located on a conductive layer of the circuit board, the first coupling line and the second coupling line are parallel to the first coupling portion and the second coupling portion respectively, and the first coupling line and the second coupling line are coupled to the closed line; At least one ground plane is located on another conductive layer of the circuit board, wherein the at least one ground plane is the reference ground for the first coupling line, the second coupling line and the closed line; as well as At least one grounding through hole is connected between the closed wire and the at least one grounding plane; The at least one grounding through hole divides the closed line into a first ring area and a second ring area with equal paths. The first coupling part and the second coupling part are located in the first ring area and the second ring area respectively. The first ring area and the second ring area are connected to a junction, and the at least one grounding through hole is connected to the junction.

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