Radio frequency filter having a circuit board with multiple resonator heads, and a resonator head having multiple arms - Patents.com

Abstract

Provided herein is a filter device. In some embodiments, the filter device includes first and second resonator stems in respective first and second openings of a PCB having first and second metal resonator heads on the first and second resonator stems, respectively. Further, in some embodiments, the filter device includes a metal resonator head having a loop portion on the resonator stem and multiple arms extending outward from the loop portion.

Description

[Technical field]

[0001] The present disclosure relates to communication systems, and more particularly to radio frequency (RF) filters. [Background technology]

[0002] One type of filter for RF applications is a resonator filter that contains a group of coaxial resonators. The overall transmission function of a resonator filter is a function of the responses of the individual resonators and also of the electromagnetic coupling between different pairs of resonators in the group.

[0003] U.S. Patent No. 5,812,036 (hereinafter the "'036 patent"), the entire disclosure of which is incorporated herein by reference, discloses different resonator filters having different configurations and topologies of the resonators. For example, the '036 patent discusses a six-stage resonator filter having a 2×3 array of cavities between input and output terminals, each cavity having a respective resonator therein. The resonator filter also includes a conductive housing that defines a portion of the outer conductor of each of the resonators. The remaining portion of the outer conductor of each resonator is formed by an internal common wall. The resonators may include, for example, either air-filled cavity resonators or dielectrically loaded coaxial resonators. Summary of the Invention

[0004] A filter apparatus according to some embodiments of the present disclosure may include a housing. The filter apparatus may include a plurality of resonator stalks within the housing. Further, the filter apparatus may include a printed circuit board (PCB) including a plurality of metal resonator heads each electrically connected to the resonator stalk.

[0005] In some embodiments, each of the metallic resonator heads includes a loop portion on a respective one of the resonator stems and at least one arm portion extending outwardly from the loop portion. The PCB may include a plurality of first openings, and the resonator stems may each extend upwardly through the first openings and through the loop portion. Additionally, the PCB may include a plurality of second openings between respective pairs of the arm portions extending toward each other.

[0006] According to some embodiments, the resonator stem may be a respective first resonator stem, and the PCB may be a first PCB on the first resonator stem. Further, the filter device may include a second resonator stem in the housing, a second PCB on the second resonator stem, and a wall in the housing between the first resonator stem and the second resonator stem.

[0007] In some embodiments, the filter arrangement may include a low pass filter on a PCB. Additionally, the resonator stem and the housing may be different portions of a single piece of metal.

[0008] According to some embodiments herein, a filter apparatus may include first and second resonator stems in respective first and second openings of a PCB having first and second metallic resonator heads on the first and second resonator stems, respectively.

[0009] In some embodiments, the first metallic resonator head may include a first loop portion on the first resonator stem and a first arm portion extending outwardly from the first loop portion. The second metallic resonator head may include a second loop portion on the second resonator stem and a second arm portion extending outwardly from the second loop portion. Additionally, the first metallic resonator head may include a third arm portion extending outwardly from the first loop portion, and the second metallic resonator head may include a fourth arm portion extending outwardly from the second loop portion.

[0010] According to some embodiments, the filter device may include third to eleventh resonator stems in respective third to eleventh openings of the PCB. Further, the PCB may have third to eleventh metal resonator heads on the third to eleventh resonator stems, respectively.

[0011] According to some embodiments herein, a filter apparatus may include a housing and a plurality of resonators within the housing, each of the resonators may include a respective resonator stem and a respective metallic resonator head including a loop portion on the resonator stem and a plurality of arms extending outwardly from the loop portion.

[0012] In some embodiments, the filter device may include a PCB, and the metal resonator head may be on the PCB. The PCB may be on top of each of the resonator stems. The metal resonator head may be on a top surface of the PCB. The tops of the resonator stems may extend through respective openings in the PCB and protrude upward beyond the top surface of the PCB. Additionally, the filter device may include a low pass filter on the PCB.

[0013] According to some embodiments, the resonator stems may be respective first resonator stems, the metal resonator heads may be respective first metal resonator heads, and the filter device may include a second resonator stem within the housing, and a wall within the housing between the first resonator stem and the second resonator stem. Further, the filter device may include a first PCB including the first metal resonator head on the first resonator stem, respectively. The filter device may include a second PCB including the second metal resonator head on the second resonator stem, respectively. The first and second PCBs may be PCBs of the first and second bandpass filters, respectively.

[0014] In some embodiments, the metallic resonator head may be a respective non-PCB metallic resonator head.

[0015] According to some embodiments, a first arm of a first metallic resonator head may vertically overlap a second arm of a second metallic resonator head.

[0016] According to some embodiments herein, a filter apparatus may include a housing and a plurality of non-PCB resonators within the housing, each of the non-PCB resonators may include a respective resonator stem and a respective metallic resonator head including a loop portion on the resonator stem and a plurality of arms extending outwardly from the loop portion.

[0017] In some embodiments, the resonator trunk may be a respective first resonator trunk, and the filter device may include a second resonator trunk within the housing, and a wall within the housing between the first resonator trunk and the second resonator trunk. Further, the first resonator trunk may be a resonator trunk of a first bandpass filter, and the second resonator trunk may be a resonator trunk of a second bandpass filter. [Brief description of the drawings]

[0018] [Figure 1A] FIG. 1 is a top perspective view of the interior of an RF filter according to an embodiment of the inventive concept. [Figure 1B] FIG. 1B is an enlarged view of a portion of the filter of FIG. 1A. [Figure 1C] FIG. 1B is a side perspective view of a cavity of the filter of FIG. 1A. [Figure 1D] 1B is a top view illustrating a method of forming the metallic resonator head of the filter of FIG. 1A. [Figure 1E] 1B is a top view illustrating a method of forming the metallic resonator head of the filter of FIG. 1A. [Figure 2A] FIG. 13 is a top view of the interior of an RF filter in accordance with a further embodiment of the inventive concept. [Figure 2B] FIG. 2B is an enlarged view of a portion of the filter of FIG. 2A. [Figure 2C] FIG. 2B is a side view of the cavity of the filter of FIG. 2A. [Figure 2D] 2B is a top view illustrating a different shape of a portion of the PCB of the filter of FIG. 2A. [Figure 2E] 2B is a top view illustrating a different shape of a portion of the PCB of the filter of FIG. 2A. [Figure 2F] FIG. 2B is a side perspective view of a cavity of the filter of FIG. 2A. [Figure 2G] 2B is a top perspective view showing an alternative shape for the metal resonator head included in the filter of FIG. 2A. [Figure 2H] 2B is a top perspective view showing an alternative shape for the metal resonator head included in the filter of FIG. 2A. [Figure 2I] 2B is a top view showing an alternative shape for the metal resonator head included in the filter of FIG. 2A. [Figure 2J] 2B is a top view showing an alternative shape for the metal resonator head included in the filter of FIG. 2A. [Figure 2K] FIG. 2B is a side view of a portion of the filter of FIG. 2A. [Figure 2L] FIG. 2B is a side view of a portion of the filter of FIG. 2A. [Figure 2M] FIG. 2B is a side view of a portion of the filter of FIG. 2A. [Figure 3A] FIG. 2B is a top view illustrating a method for laser tuning the filter of FIG. 2A. [Figure 3B] FIG. 2B is a top view illustrating a method for laser tuning the filter of FIG. 2A. [Figure 4A] FIG. 13 is a top view of the interior of an RF filter in accordance with a further embodiment of the inventive concept. [Figure 4B] FIG. 4B is an enlarged view of a portion of the filter of FIG. 4A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In accordance with an embodiment of the inventive concept, an RF filter device is provided that includes a plurality of resonators. In a typical cavity filter, the resonators act as the inner conductor and the housing acts as the outer conductor. Each resonator may include a stalk and a resonator head. The base of the stalk may be galvanically connected to the housing and the distal end of the stalk may be spaced apart from the housing. Inductive coupling between adjacent resonators may be achieved by a gap between the bulkheads of the housing cavity. Similarly, capacitive coupling may occur between the spaced apart distal ends of adjacent stalks. The resonator head may be attached at or near the distal end of the stalk to increase the capacitive coupling. The amount of capacitive coupling between the resonators may be adjusted (e.g., increased) by the positioning, size, and shape of the resonator head, which may also be referred to herein as a "resonator hat."

[0020] It may be desirable to provide inexpensive resonator heads. Planar (i.e., flat) metal resonator heads may be less expensive than dished resonator heads, but if the resonator heads are at different heights or are curved (and therefore not very flat), the coupling between the resonator heads may be inconsistent. However, in accordance with embodiments of the inventive concepts, a PCB may facilitate the use of resonator heads that are inexpensive, flat, precisely (e.g., consistently) positioned, and relatively easy to assemble.

[0021] For example, according to an embodiment of the inventive concept, multiple resonator heads providing coupling (e.g., capacitive coupling) between the resonators may be formed on a single PCB and then mounted on multiple resonator stalks. In other embodiments, transmission lines and / or inductive couplings may be formed on a single PCB, which may be mounted on multiple resonator stalks. Additionally, stripline-based filter structures, such as low-pass filters, may also be implemented on the same integrated PCB with multiple resonator heads. Other elements that may be included on the PCB are connector pins, connectors, and RF couplers. Because filter elements such as resonator heads may be implemented on an integrated PCB, manufacturing variations may be reduced and assembly tolerances may be highly controlled.

[0022] Mounting the filter elements on a PCB may also reduce the need for filter tuning. Tuning adjustments to PCB-based filters may be performed by conventional techniques, such as, for example, by bringing a metal material close to the open end of a coupling element (e.g., a resonator head). Additionally, the inventive concept may facilitate other filter tuning techniques, such as tuning by removing metal from a PCB using a laser.

[0023] Exemplary embodiments of the inventive concept will now be described in more detail with reference to the accompanying drawings.

[0024] 1A is a top perspective view of the interior of an RF filter apparatus 100 in accordance with an embodiment of the inventive concept. Filter 100 is a device that includes resonators R in respective cavities C within a housing 110. Each resonator R includes a resonator stem 101 and a metallic resonator head 102 that rests on stem 101. In some embodiments, resonator heads 102 may be respective flat (as opposed to dished) resonator heads.

[0025] The inner wall 120 may extend into the housing 110 between the two filters including the resonators R. For example, the two filters may each have a separate transmission path to two ports of the filter 100. The ports may be coupled to respective antenna ports, such as ports of a base station antenna (e.g., a 64T64R antenna or other large multiple-input-multiple-output ("MIMO") antenna). In some embodiments, the two filters separated by the inner wall 120 may be identical mirror bandpass filters. The housing 110 may also include a cavity wall CW between the inner wall 120 and an outer wall of the housing 110. A cavity C may be defined by a combination of the cavity wall CW, the inner wall 120, and / or the outer wall. A lid (not shown in FIG. 1A) may cover the cavity C.

[0026] Adjacent, spaced apart resonators R may be electromagnetically (e.g., capacitively and / or inductively) coupled to one another. Additionally, a metal piece 103 adjacent to and spaced apart from resonator R may couple resonator R to a port of filter 100.

[0027] FIG. 1B is an enlarged view of a portion of the filter 100 (FIG. 1A). In particular, FIG. 1B shows a pair of resonators R-1, R-2 that are capacitively coupled to each other by their respective resonator heads 102. Each resonator head 102 includes a loop portion 102-L that extends around the upper portion 101-U of the resonator trunk 101. Each resonator head 102 also includes at least one arm portion 102-A that is connected to the loop portion 102-L and extends outward (e.g., protrudes laterally) from the loop portion 102-L. In some embodiments, two or three arm portions 102-A may extend from the loop portion 102-L. The loop portion 102-L and the arm portions 102-A extending therefrom may be different portions of a single piece of metal.

[0028] The arm portion 102-A of the first resonator R-1 may extend along the arm portion 102-A of the second resonator R-2 coupled thereto. For example, the resonator head 102 may be a copper (or other conductive) coupling element that contributes to the quality ("Q") value 1800 of the filter 100. Thus, the loop portion 102-L and the arm portion 102-A may each comprise copper. The terms "arm" and "arm portion" may be used interchangeably herein.

[0029] FIG. 1C is a side perspective view of the cavity of the filter 100 (FIG. 1A). The cavity C may be defined by one or more cavity walls CW. The cavity walls CW are typically metal, but are depicted in transparency in FIG. 1C for ease of illustrating the resonator stem 101 and the metallic resonator head 102 in the cavity C. The stem 101 in the cavity C may include a base portion 101-B and a top portion 101-U. In some embodiments, the stem 101 may have a tapered shape such that the top portion 101-U is narrower than the base portion 101-B. The loop portion 102-L of the resonator head 102 may be electrically connected to the top portion 101-U. For example, the loop portion 102-L may be soldered to the top portion 101-U. In some embodiments, the resonator head 102 may be formed by soldering loop portions 102-L of a flat metal sheet to each stem 101 and then cutting away some of the interconnecting metal between the stems 101 to provide a pair of spaced apart arm portions 102-A.

[0030] The upper portion 101-U of the stem 101 may be (i) the top half, (ii) the top third, or (iii) the top quarter of the stem 101. Thus, the resonator head 102 on the stem 101 is closer to the top end of the stem 101 than to the bottom end of the stem 101. Additionally, the stem 101 may also be referred to as the "resonator pedestal."

[0031] 1D and 1E are top views illustrating a method of forming the metal resonator head 102 of the filter 100 (FIG. 1A). With reference to FIG. 1D, multiple resonator heads 102 may be formed from the same metal sheet. Thus, a metal interconnect, such as a metal bridge 105, may connect adjacent resonator heads 102. With reference to FIG. 1E, the metal bridge 105 may be removed (e.g., by cutting) to separate the resonator heads 102 from each other. In some embodiments, the metal bridge 105 may be removed after the loop portion 102-L of the resonator 102 is soldered to the respective resonator trunk 101 (FIG. 1C). Furthermore, FIG. 1E also illustrates that the outer diameter D of the loop portion 102-L may be narrower than the length L of the arm portion 102-A protruding from the loop portion 102-L.

[0032] FIG. 2A is a top view of the interior of an RF filter device 200 according to a further embodiment of the inventive concept. Similar to filter 100 (FIG. 1A), filter 200 has a resonator R inside a housing 210. For example, filter 200 may include two filters, where a resonator R1 of a first filter may be separated from a resonator R2 of a second filter by an inner wall 220 inside the housing 210. Resonators R1 and R2 may provide respective paths (e.g., transmission paths) between two pairs of ports of filter 200. Some of the ports may be coupled to respective antenna ports, such as ports of a base station antenna. In FIG. 2A, the first and second filters each include eleven resonators R. However, in some embodiments, more (e.g., twelve or more) or fewer (e.g., ten, nine, eight, or fewer) resonators R may be included. Furthermore, for simplicity of illustration, only two resonators R1-1 and R1-2 are labeled for the first filter, and only two resonators R2-1 and R2-2 are labeled for the second filter.

[0033] Unlike filter 100, the multiple metal resonator heads 202 (FIG. 2B) of resonator R of filter 200 may be on a single PCB. For example, resonator R1 of the first filter and resonator R2 of the second filter may have first and second multiple resonator heads 202 on their respective PCBs 231 and 232. Thus, each PCB 231 and 232 may have multiple resonator heads 202. In some embodiments, PCBs 231 and 232 may include a high frequency laminate, such as RO3003® laminate by Rogers Corporation. Furthermore, in some embodiments, PCB 231 and / or PCB 232 may include additional electrical components. By way of example, PCBs 231 and 232 may include low pass filters 241 and 242, respectively.

[0034] PCBs 231 and 232 facilitate easier assembly of filter 200 as compared to assembly of filter 100. For example, because filter 200 has PCB-based resonator head 202 instead of non-PCB resonator head 102 (FIG. 1A), there is no need to cut metal to form resonator head 202. In contrast, cutting interconnect metal to form resonator head 102 may move and / or bend resonator head 102. As a result, tolerances for PCB-based filter 200 may be improved relative to filter 100.

[0035] Filters 100 and 200 may each have an operating frequency range (e.g., passband) of 3480 megahertz ("MHz") to 3800 MHz, or a portion thereof. Over the operating frequency range, filter 200 may have a maximum insertion loss of 1.8 decibels ("dB"), a variation in insertion loss of less than 1 dB, and a maximum group delay distortion of 65 nanoseconds ("ns").

[0036] In some embodiments, the housing 210 may be a metal housing. For example, in some embodiments, a single machined or die-cast part includes the outer wall, bottom, cavity wall CW (FIG. 2C), inner wall 220, and / or resonator stem 201 (FIG. 2B) of the housing 210. As an example, the stem 201 and the housing 210 may be different parts of a single piece of metal (e.g., the stem 201 may be die-cast with the housing 210), or the stem 201 may be connected to the housing 210 by screws or soldering. Similarly, with reference to FIG. 1A, a single machined or die-cast part may include the outer wall, bottom, cavity wall CW, inner wall 120, and / or 101 of the housing 110. A lid 290 (FIG. 2G) may cover the cavity C.

[0037] FIG. 2B is an enlarged view of a portion of the top surface 231U of the PCB 231 of the filter 200 (FIG. 2A). The PCB 231 may have an opening 260 between each pair of resonators R. As used herein, a term such as "pair" may refer to two resonators R (or components thereof) having an opening 260 therebetween and no third resonator R therebetween. For example, FIG. 2B shows an opening 260 between (a) the arm portion 202-A of the metal resonator head 202 of the first resonator R1-1 and (b) the arm portion 202-A of the metal resonator head 202 of the second resonator R1-2. In some embodiments, the opening 260 may include a middle / end portion 260-E between the respective ends of the pair of arm portions 202-A, as well as one or more side portions 260-S extending along the sides of the pair of arm portions 202-A. As an example, the opening 260 may be an H-shaped or U-shaped hole in the PCB 231 .

[0038] Each resonator head 202 may have at least one arm 202-A. As an example, the resonator heads 202 shown in FIG. 2B each have two arm sections 202-A. The other resonator heads 202 may similarly have two arm sections 202-A, or one arm section 202-A or three arm sections 202-A. In some embodiments, each arm section 202-A may be paired and electromagnetically coupled with an arm section 202-A of another resonator R.

[0039] Each resonator head 202 may also have a loop portion 202-L from which one or more arm portions 202-A extend outwardly (i.e., laterally). Similar to that shown in FIG. 1E, the length of the arm portion 202-A may be greater than the outer diameter of the loop portion 202-L from which it extends. Additionally, the loop portion 202-L and the arm portions 202-A extending therefrom may be different portions of a single piece of metal.

[0040] A plurality of loop portions 202-L are on each resonator stem 201 and are electrically connected (e.g., via solder). For example, the loop portions 202-L may extend continuously around the circumference of the top portion 201-U (FIG. 2C) of the stem 201. However, the loop portions 202-L need not completely surround the stem 201. In some embodiments, the loop portions 202-L may extend partially around the circumference of the top portion 201-U of the stem 201. For example, the loop portions 202-L may extend approximately 180 degrees (or less) around the circumference of the top portion 201-U. Thus, as used herein, terms such as "loop" may refer to a partial loop or a complete (e.g., 360 degree) loop.

[0041] In some embodiments, PCB 231 may have curved openings 270 extending adjacent to each loop portion 202-L. Openings 270 may be spaced apart from adjacent openings 260 or connected to openings 260. Locating openings 260 and 270 (replacing PCB dielectric material) near resonator head 202 may improve the Q performance of filter 200 relative to filters having PCBs lacking openings 260 and 270. For example, filter 200 may have a Q value of greater than 1500.

[0042] 2C is a side view of cavity C of filter 200 (FIG. 2A). The dimensions of cavity C may be, for example, 9.2 millimeters ("mm") wide, 16 mm long, and 14 mm high. The cavity walls CW of cavity C are typically metal, but are depicted in transparency in FIG. 2C for ease of illustrating the resonator trunk 201 and PCB 231 within cavity C.

[0043] As shown in FIG. 2C, the PCB 231 may have a top surface 231U and an opposite bottom surface 231L, and may be on the top 201-U of the stem 201. In some embodiments, the metallic resonator head 202 of the resonator R (FIG. 2B) may include a bottom portion 202-B that is on the bottom surface 231L of the PCB 231, and a top portion 202-U that is on the top surface 231U of the PCB 231. The top portion 202-U and the bottom portion 202-B may each include a loop portion 202-L (FIG. 2B) and at least one arm portion 202-A (FIG. 2B). Additionally, the stem 201 includes a base portion 201-B that may have a diameter that is wider than the diameter of the top portion 201-U and wider than the inner diameter of the loop portion 202-L. Thus, the resonator head 202 may remain in a relatively high position on the stem 201, such as the top quarter thereof.

[0044] 2D and 2E are top views showing different shapes of a portion of the PCB 231 of the filter 200 (FIG. 2A). The portion shown in FIG. 2D shows a metallic resonator head 202 having a loop portion 202-L bounded by two openings 270 spaced apart from respective outer edges (i.e., opposing outer walls) of the PCB 231. Thus, the PCB 231 in FIG. 2D has a generally rectangular shape around the resonator head 202.

[0045] However, the PCB 231 of the filter 200 is not limited to the generally rectangular shape shown in Figures 2A and 2D. For example, the PCB 231 of Figure 2E has a shape that tapers toward the loop portion 202-L of the resonator head 202. This taper is due to a larger opening 270 that excludes a portion of the outer edge of the more rectangular PCB 231 of Figure 2D. Therefore, the tapered PCB 231 of Figure 2E has less dielectric material than the more rectangular PCB 231 of Figure 2D. As a result, the tapered PCB 231 of Figure 2E has slightly improved performance (e.g., the Q value of the filter 200 increases from 1530 to 1560) relative to the more rectangular PCB 231 of Figure 2D.

[0046] 2D and 2E also show that the PCB 231 has an opening 250 that connects with an opening in the loop portion 202-L of the resonator head 202. Thus, the PCB 231 may be placed on the resonator stem 201 (FIG. 2B) having an upper portion 201-U (FIG. 2C) that fits into the opening 250. In some embodiments, multiple stems 201 may extend upward (i) through the respective openings 250 of the PCB 231 and (ii) through the respective loop portions 202-L of the resonator head 202. Thus, the upper portion 201-U (FIG. 2C) of each stem 201 may protrude upward beyond the upper surface 231U of the PCB 231, as exemplified by the stem 201 shown in FIG. 2F. The filter 200 may similarly include a stem 201 that extends through a respective opening in the second PCB 232 (FIG. 2A). Additionally, the loop portion 202-L of the resonator head 202 may be electrically connected (eg, via solder) to the upper portion 201-U of each trunk 201.

[0047] FIG. 2F is a side perspective view of the cavity C of the filter 200 (FIG. 2A). As shown in FIG. 2F, the tuning element 280 may vertically overlap the upper portion 201-U of the resonator trunk 201 that is in the cavity C. The tuning element 280 may be a dielectric tuning element or a metallic tuning element, and both the dielectric tuning element and the metallic tuning element may vary the capacitive coupling between the resonators R (FIG. 2A) and / or (b) between the resonators R and the housing 210 (FIG. 2A). In some embodiments, the tuning element 280 may be a tuning stub or a tuning screw. Examples of tuning stubs and tuning screws are discussed in U.S. Pat. No. 10,050,323, the entire disclosure of which is incorporated herein by reference.

[0048] 2G and 2H are top perspective views illustrating alternative shapes for the metallic resonator heads 202 included in the filter 200 (FIG. 2A). Referring to FIG. 2G, the first and second resonator heads 202-1 and 202-2 generally have a propeller shape with rounded ends. In contrast, FIG. 2H illustrates resonator head arm portions 202-A having relatively wide ends 202-E. In particular, each arm portion 202-A may have a main portion 202-M and a wide end portion 202-E that extends laterally beyond the sidewall of the main portion 202-M. Due to their expanded width, the pair of wide ends 202-E may have a stronger coupling (e.g., capacitive coupling) therebetween than ends that do not extend laterally relative to the main portion 202-M.

[0049] FIG. 2G also shows that filter 200 may include a lid 290 having an opening 290H through which tuning element 280 may extend across each resonator stem 201. Tuning element 280 may adjust the vertical distance (i.e., vertical tuning range) by up to 2.2 mm. In some embodiments, lid 290 may cover resonators R1 and R2 (FIG. 2A) of respective PCBs 231 and 232 (FIG. 2A). Although lid 290 is typically a metal (e.g., aluminum) cover, lid 290 is depicted in transparency in FIG. 2G to facilitate illustration of underlying cavity C and elements therein.

[0050] 2I and 2J are top views showing alternative shapes for the metallic resonator head 202 included in the filter 200 (FIG. 2A). The shapes shown in FIG. 2I and 2J provide alternative ways of increasing coupling between a pair of resonator heads 202. For example, FIG. 2I illustrates a resonator head arm portion 202-A having an end 202-T extending between the first and second ends 202-T1 and 202-T2 of another resonator head arm portion 202-A. Thus, the end 202-T may be coupled to both the ends 202-T1 and 202-T2, thereby enhancing the coupling between the pair of resonator heads 202.

[0051] As another example, FIG. 2J shows plated through holes 204 at the ends 202-T of a pair of resonator head arm portions 202-A. The plated through holes 204 may be plated with a conductive material that extends continuously from the top surface 231U of the PCB 231 (FIG. 2C) to the opposite bottom surface 231L of the PCB 231. For example, the conductive material in the plated through holes 204 may extend continuously from the top 202-U of the resonator head 202 (FIG. 2C) to the bottom 202-B of the resonator head 202 (FIG. 2C). Furthermore, the plated through holes 204 may be aligned near the outer edge of the ends 202-T. As a result, the plated through holes 204 can increase the coupling between the pair of resonator heads 202.

[0052] 2K-2M are side views of a portion of the filter 200 (FIG. 2A). Referring to FIG. 2K, a pair of resonator stems 201 may be coupled to each other by an inductive coupling 240, which may be a conductive layer on the lower PCB 221 below the upper PCB 231. Thus, the upper PCB 231 may include a resonator head 202, and the lower PCB 221 may include one or more inductive couplings 240. Similar to the upper PCB 231, the lower PCB 221 may include an opening through which each stem 201 protrudes vertically. Additionally, referring to FIG. 2L, in some embodiments, the lower PCB 221 may include a transmission line 245.

[0053] 2M, the arm portion 202-A of the first metallic resonator head 202 may, in some embodiments, vertically overlap with the arm portion 202-AL of the second metallic resonator head 202. For example, the arm portion 202-AL (of one resonator head 202) on the lower surface 231L of the PCB 231 may extend below the arm portion 202-A (of another resonator head 202) on the upper surface 231U of the PCB 231. This vertical overlap between the arm portions 202-AL and 202-A of different resonator heads 202 may enhance the capacitive coupling between the resonator heads 202.

[0054] 3A and 3B are top views illustrating a method for laser tuning filter 200 (FIG. 2A). As shown in FIG. 3A, filter 200 includes a metallic resonator head 202 having multiple metallic resonator arms 202-A on the top surface 231U of PCB 231. For tuning purposes, it may be desirable to remove a portion of the metal of one of the resonator arms 202-A. Thus, as shown in FIG. 3B, a portion of the metal of the resonator arm 202-A on the left side of the resonator head 202 may be removed using a laser. As a result, filter 200 may be tuned.

[0055] In some embodiments, filter apparatus 100 (FIG. 1A) and 200 (FIG. 2A) may each include one or more in-line resonator filters, which may be implemented with respective linear arrays having any number of inner conductors (e.g., resonators R) with two input / output ports respectively connected to the first and last inner conductors of each linear array. As an example, first and second linear arrays of resonators R may be provided on PCBs 231 and 232 (FIG. 2A), respectively. Examples of in-line resonator filters are discussed in U.S. Pat. No. 10,236,550, the entire disclosure of which is incorporated herein by reference. Additionally, filters 100 and 200 may be time-division duplex (TDD) filters, which may be less susceptible to passive intermodulation (PIM) distortion than frequency-division duplex (FDD) filters.

[0056] 4A is a top view of the interior of an RF filter device 400 according to a further embodiment of the inventive concept. Similar to filter 100 (FIG. 1A) and filter 200 (FIG. 2A), filter 400 has a resonator R inside a housing 410. For example, filter 400 may include two filters, where a resonator R1 of a first filter may be separated from a resonator R2 of a second filter by an inner wall 420 inside the housing 410. Resonators R1 and R2 may provide respective paths (e.g., transmission paths) between two pairs of ports of filter 400. Some of the ports may be coupled to respective antenna ports, such as ports of a base station antenna. For ease of explanation, only three resonators R1-1, R1-2, and R1-3 are labeled for the first filter, and only three resonators R2-1, R2-2, and R2-3 are labeled for the second filter.

[0057] 4B is an enlarged view of a portion of the filter 400 of FIG. 4A. As shown in FIG. 4B, (a) the arm portion 402-A of the metal resonator head 402 of the first resonator R1-1 and (b) the arm portion 402-A of the metal resonator head 402 of the second resonator R1-2 may each extend into (e.g., through) an opening OCW of a cavity wall CW between the resonator trunks 401 of the resonators R1-1 and R1-2, respectively. Thus, the pair of arm portions 402-A may be electromagnetically coupled to each other. For example, the pair of arm portions 402-A may be horizontally offset from each other (i.e., adjacent and horizontally spaced apart) in the opening OCW such that one side of the arm portion 402-A is electromagnetically coupled to the nearest side of the other arm portion 402-A. Furthermore, the opening OCW may be referred to as a "window" or "notch" in the cavity wall CW, which may be a metal wall.

[0058] The arm portion 402-A extends horizontally outward from the respective loop portion 402-L of the resonator head 402, and the loop portion 402-L is on the respective resonator trunk 401. For example, the arm portion 402-A of the resonator head 402 of the first resonator R1-1 may extend outward from the loop portion 402-L of that resonator head 402 toward the loop portion 402-L of the resonator head 402 of the second resonator R1-2. Similarly, the arm portion 402-A of the resonator head 402 of the second resonator R1-2 may extend outward from the loop portion 402-L of that resonator head 402 toward the loop portion 402-L of the resonator head 402 of the first resonator R1-1. Similar to the non-PCB resonator head 102 (FIG. 1A), the resonator head 402 may be a non-PCB resonator head.

[0059] Unlike the way the non-PCB resonator heads 102 are shown in FIG. 1A, some resonator heads 402 may have only a single arm portion 402-A rather than multiple arm portions. As an example, each of the first resonator R1-1 and the second resonator R1-2 may have only a single arm portion 402-A extending outwardly from a respective loop portion 402-L. Additionally, other resonator heads 402, such as the resonator head 402 of the third resonator R1-3, may have a loop portion 402-L that does not include any arm portion 402-A extending outwardly therefrom.

[0060] 1A, the resonator heads 402 may be bowl / dish-shaped rather than flat. Thus, each resonator head 402 may slope downward from the top of its loop portion 402-L towards the respective resonator trunk 401. In some embodiments, the top of the loop portion 402-L may be at a higher vertical level than the top of the resonator trunk 401.

[0061] Resonators R2-1, R2-2, and R2-3 (FIG. 4A) may include similar components / structures as those shown in FIG. 4B for resonators R1-1, R1-2, and R1-3, respectively. For example, each of resonators R2-1, R2-2 may have a single arm extending horizontally outward from a respective loop portion, and resonator R2-3 may have a loop portion without any arm extending outward therefrom. Furthermore, the pair of arms may be electromagnetically coupled to each other, and the resonator heads of resonators R2-1, R2-2, and R2-3 may be bowl / dish shaped.

[0062] The RF filter apparatus 200 (FIG. 2A) according to an embodiment of the inventive concept may provide many advantages. These advantages include easier assembly and improved tolerances by having multiple metal resonator heads 202 (FIG. 2B) on a single PCB 231 (FIG. 2B). In contrast, tolerances may be worse with resonator heads 102 (FIG. 1A) formed by metal punching, which may involve cutting interconnecting metal pieces using large forces. The PCB 231 may also have other elements, including stripline-based filter structures such as low-pass filter 241 (FIG. 2A). In some embodiments, the filter 200 may comprise two linear arrays of resonators R on respective PCBs 231 and 232 (FIG. 2A).

[0063] Furthermore, the inventive concept may provide an RF filter device 100 (FIG. 1A) having metal resonator heads 102 (FIG. 1A) including arm portions 102-A (FIG. 1B) extending toward each other to enhance coupling between pairs of resonator heads 102 for disk-shaped (e.g., dish-shaped) resonator heads that are spaced farther apart from each other. Although the resonator heads 102 are not on a PCB, the PCB-based resonator heads 202 of the filter 200 may similarly have arm portions 202-A (FIG. 2B) that may enhance coupling between pairs of resonator heads 202. In some embodiments, each resonator head 102 may have a loop portion 102-L (FIG. 1B) from which multiple arm portions 102-A extend laterally. Similarly, each resonator head 202 may have a loop portion 202-L (FIG. 2B) from which multiple arm portions 202-A extend laterally.

[0064] The inventive concept has been described above with reference to the accompanying drawings. The inventive concept is not limited to the illustrated embodiments. Rather, these embodiments are intended to fully and completely disclose the inventive concept to those skilled in the art. In the drawings, like numbers refer to like elements throughout. The thickness and dimensions of some components may be exaggerated for clarity.

[0065] Spatially relative terms, such as "under," "below," "lower," "over," "upper," "top," "bottom," and the like, may be used herein to facilitate description of one element or feature relative to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, an element described as "under" or "under" another element or feature would be oriented "above" the other element or feature. Thus, the exemplary term "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0066] As used herein, unless otherwise stated, terms such as "attachable," "connected," "interconnected," "contact," "mounted," and the like can mean either a direct or indirect attachment or contact between elements.

[0067] Well-known functions or configurations may not be described in detail for brevity and / or clarity. As used herein, terms such as "and / or" include any and all combinations of one or more of the associated listed items.

[0068] The terms used herein are merely for the purpose of describing specific embodiments only and are not intended to limit the concept of the present invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including" as used herein specify the presence of the stated features, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, operations, elements, components and / or groups thereof. [Configuration 1] 1. A filter device, comprising: A housing and a plurality of resonator stems within the housing; a printed circuit board (PCB) including a plurality of metal resonator heads each electrically connected to the resonator stem. [Configuration 2] Each of the metallic resonator heads is a loop portion on each of the resonator stems; and at least one arm portion extending outwardly from the loop portion. [Configuration 3] the PCB further comprises a plurality of first openings; 3. The filter apparatus of claim 2, wherein the resonator stems extend upwardly through the first opening and through the loop portion, respectively. [Configuration 4] 4. The filter apparatus of configuration 3, wherein the PCB further comprises a plurality of second openings between respective pairs of the arm portions extending toward one another. [Configuration 5] the resonator stem is a respective first resonator stem, the PCB is a first PCB on the first resonator stem; The filter device comprises: a second resonator stem within the housing; and a second PCB on the second resonator stem; 2. The filter apparatus of claim 1, further comprising: a wall within the housing between the first resonator stem and the second resonator stem. [Configuration 6] 2. The filter apparatus of configuration 1, further comprising a low pass filter on the PCB. [Configuration 7] 2. The filter apparatus of claim 1, wherein the resonator stem and the housing are different portions of a single piece of metal. [Configuration 8] A filter apparatus comprising first and second resonator stems in respective first and second openings of a printed circuit board (PCB) having first and second metallic resonator heads respectively on the first and second resonator stems. [Configuration 9] the first metallic resonator head comprising a first loop portion on the first resonator stem and a first arm portion extending outwardly from the first loop portion; the second metallic resonator head comprising a second loop portion on the second resonator stem and a second arm portion extending outwardly from the second loop portion; 9. The filter device of configuration 8. [Configuration 10] the first metallic resonator head further includes a third arm portion extending outwardly from the first loop portion; the second metallic resonator head further includes a fourth arm portion extending outwardly from the second loop portion. 10. The filter device of configuration 9. [Configuration 11] The PCB further includes third to eleventh resonator stems in the third to eleventh openings, respectively; The PCB has third to eleventh metal resonator heads on the third to eleventh resonator stems, respectively. 9. The filter device of configuration 8. [Configuration 12] 1. A filter device, comprising: A housing and A plurality of resonators within the housing, each of the resonators comprising: Each resonator stem, and a plurality of resonators, each including a metallic resonator head including a loop portion on the resonator stem and a plurality of arms extending outwardly from the loop portion; A filter device comprising: [Configuration 13] 13. The filter apparatus of configuration 12, further comprising a printed circuit board (PCB), the metal resonator head being on the PCB. [Configuration 14] 14. The filter apparatus of configuration 13, wherein the PCB is on top of each of the resonator stems. [Configuration 15] 15. The filter apparatus of configuration 14, wherein the metal resonator head is on a top surface of the PCB. [Configuration 16] 16. The filter apparatus of configuration 15, wherein the upper portions of the resonator stems extend through respective openings in the PCB and protrude upwardly beyond the top surface of the PCB. [Configuration 17] 14. The filter apparatus of configuration 13, further comprising a low pass filter on the PCB. [Configuration 18] the resonator stem is a respective first resonator stem, the metallic resonator head is a respective first metallic resonator head, The filter device comprises: a second resonator stem within the housing; and 13. The filter apparatus of claim 12, further comprising: a wall within the housing between the first resonator stem and the second resonator stem. [Configuration 19] a first printed circuit board (PCB) including the first metallic resonator heads on the first resonator stems, respectively; a second PCB including second metallic resonator heads on the second resonator stems, The first PCB and the second PCB are PCBs for a first bandpass filter and a second bandpass filter, respectively; 19. The filter device of claim 18. [Configuration 20] 13. The filter apparatus of configuration 12, wherein the metal resonator heads are respective non-printed circuit board (PCB) metal resonator heads. [Configuration 21] 13. The filter apparatus of configuration 12, wherein a first one of the arms of a first one of the metal resonator heads vertically overlaps a second one of the arms of a second one of the metal resonator heads. [Configuration 22] 1. A filter device, comprising: A housing and a plurality of non-printed circuit board (PCB) resonators within the housing, each of the non-PCB resonators comprising: Each resonator stem, and a plurality of non-PCB resonators including a respective metallic resonator head including a loop portion on the resonator stem and a plurality of arms extending outwardly from the loop portion; A filter device comprising: [Configuration 23] the resonator stem is a respective first resonator stem, The filter device comprises: a second resonator stem within the housing; and a wall within the housing between the first resonator stem and the second resonator stem, 23. The filter device of claim 22. [Configuration 24] the first resonator stem is a resonator stem of a first bandpass filter; The second resonator stem is a resonator stem of a second bandpass filter. 24. The filter device according to claim 23. [Configuration 25] 1. A filter device, comprising: A housing and a plurality of non-printed circuit board (PCB) resonators within the housing, each of the non-PCB resonators comprising: Each resonator stem, and a plurality of non-PCB resonators each including a metallic resonator head including a loop portion on the resonator stem and an arm extending outwardly from the loop portion; A filter device comprising: [Configuration 26] 26. The filter apparatus of configuration 25, wherein the first and second of the metallic resonator heads respectively comprise first and second arms that are electromagnetically coupled to each other. [Configuration 27] 27. The filter apparatus of configuration 26, wherein the first and second arms each extend through an opening in a wall of the housing. [Configuration 28] 28. The filter apparatus of configuration 27, wherein the wall comprises a metallic cavity wall between first and second of the resonator trunks having the first and second of the metallic resonator heads, respectively. [Configuration 29] the non-PCB resonator includes a first non-PCB resonator; the filter apparatus further comprising a second non-PCB resonator within the housing; Each of the second non-PCB resonators comprises: Each resonator stem, each metal resonator head having a loop portion on said resonator stem and not including any arms extending outwardly therefrom; 26. The filter device of claim 25. [Configuration 30] A filter device comprising first and second resonator stems having first and second metallic resonator heads, respectively, A filter apparatus, wherein the first and second metallic resonator heads each include first and second arms each extending into an opening in a wall between the first and second resonator stems. [Configuration 31] 31. The filter apparatus of claim 30, wherein the first and second arms are electromagnetically coupled to each other. [Configuration 32] 32. The filter apparatus of configuration 31, wherein the first and second arms are horizontally offset from one another within the opening.

Claims

1. 1. A filter device comprising: A housing and a plurality of resonator stems within the housing; a printed circuit board (PCB) including a plurality of metallic resonator heads electrically connected to the plurality of resonator stems, respectively; a low pass filter on the PCB; A filter device comprising:

2. Each of the metallic resonator heads is a loop portion on each of the plurality of resonator stems; and The filter device of claim 1 , comprising at least one arm portion extending outwardly from the loop portion.

3. the PCB further comprising a plurality of first openings; The filter device of claim 2 , wherein the plurality of resonator stems each extend through the first opening and upwardly through the loop portion.

4. The filter device of claim 3 , wherein the PCB further comprises a plurality of second openings between respective pairs of the arm portions that extend toward one another.

5. the plurality of resonator stems are respective first resonator stems; the PCB is a first PCB on the first resonator stem; The filter device comprises: a second resonator stem within the housing; a second PCB on the second resonator stem; and The filter device of claim 1 , further comprising a wall within the housing between the first resonator stem and the second resonator stem.

6. The filter device of claim 1 , wherein the multiple resonator stems and the housing are different portions of a single piece of metal.

7. a first of the metallic resonator heads comprising a first loop portion on a first of the plurality of resonator stems and a first arm portion extending outwardly from the first loop portion; 2. The filter device of claim 1 , wherein a second of the metallic resonator heads includes a second loop portion on a second of the plurality of resonator stems, a second arm portion extending outwardly from the second loop portion.

8. the first of the metallic resonator heads further includes a third arm portion extending outwardly from the first loop portion; 8. The filter device of claim 7, wherein the second of the metallic resonator heads further includes a fourth arm portion extending outwardly from the second loop portion.

9. the PCB is on a top portion of each of the plurality of resonator stems; the metallic resonator head is on a top surface of the PCB; 2. The filter device of claim 1, wherein the upper portions of the plurality of resonator stems extend through respective openings in the PCB and protrude upwardly beyond the top surface of the PCB.

10. A filter device comprising: A housing and a plurality of first resonator stems within the housing; a plurality of second resonator stems within the housing; a first printed circuit board (PCB) on the plurality of first resonator stems, the first PCB including a plurality of metal resonator heads electrically connected to the plurality of first resonator stems respectively; a second PCB on the plurality of second resonator stems; a wall within the housing between the plurality of first resonator stems and the plurality of second resonator stems; A filter device comprising:

Images