Layered filter device

Abstract

To realize a laminated filter device that can suppress changes in characteristics caused by manufacturing variations.SOLUTION: A filter device 1 includes a ground conductor layer 512, 597, 662, at least one through hole electrically connected to the ground conductor layer, a first resonator conductor layer 591 and a second resonator conductor layer 592 arranged to sandwich the at least one through hole, and a laminated body 50. The first resonator conductor layer 591 extends along a first direction away from the at least one through hole, that is, the -X direction. The second resonator conductor layer 592 extends along the second direction, that is, the X direction, away from the at least one through hole.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a multilayer filter device having two resonators. [Background technology]

[0002] One type of electronic component used in a communication device is a bandpass filter having a plurality of resonators. Each of the resonators has, for example, a conductor portion that is long in one direction. Bandpass filters used in small communication devices in particular are required to be compact. Known bandpass filters suitable for miniaturization include those that use a laminate including a plurality of stacked dielectric layers and a plurality of stacked conductor layers.

[0003] Patent Document 1 discloses a bandpass filter having four quarter-wave resonators, which uses a laminate including a plurality of stacked dielectric layers and a plurality of stacked conductor layers. In this bandpass filter, two resonators are formed by two resonator conductors each having a shape elongated in the X direction, and the other two resonators are each formed by two resonator conductors each having a shape elongated in the Y direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-125804 Summary of the Invention [Problem to be solved by the invention]

[0005] In a bandpass filter using a laminate, the positions of conductor layers and through holes may be misaligned due to manufacturing variations. Consider the case where the positions of two resonator conductors, each elongated in the Y direction, are misaligned in the Y direction in the bandpass filter disclosed in Patent Document 1. In this case, both resonator conductors become longer or shorter. Some resonator characteristics change depending on the length of the resonator conductors. Therefore, if the lengths of the two resonator conductors change in the same way, the characteristics of the two resonators also change in the same way. As a result, the characteristics of the bandpass filter as a whole may change significantly.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a multilayer filter device that can suppress changes in characteristics due to manufacturing variations. [Means for solving the problem]

[0007] The multilayer filter device of the present invention includes a ground conductor layer electrically connected to a ground, at least one through hole electrically connected to the ground conductor layer, Ground conductor layer The resonator includes a first resonator conductor layer and a second resonator conductor layer arranged to sandwich a grounding layer, at least one through hole, and a laminate including a plurality of laminated dielectric layers for integrating the first resonator conductor layer and the second resonator conductor layer. The first resonator conductor layer extends in a first direction away from the at least one through hole. The second resonator conductor layer extends in a second direction away from the at least one through hole. One end of each of the first resonator conductor layer and the second resonator conductor layer is connected to the ground conductor layer.

[0008] In the multilayer filter device of the present invention, each of the first and second resonator conductor layers may form a resonator having one end shorted and the other end open, and in this case, each of the first and second resonator conductor layers may be electrically connected to at least one through hole.

[0009] Furthermore, in the multilayer filter device of the present invention, at least one through hole may include a plurality of through holes arranged along a direction perpendicular to the stacking direction of the plurality of dielectric layers and perpendicular to at least one of the first direction and the second direction.

[0010] In the multilayer filter device of the present invention, the first direction and the second direction may be opposite to each other.

[0011] In addition, the multilayer filter device of the present invention may further include a third resonator conductor layer coupled to the first resonator conductor layer, and a fourth resonator conductor layer coupled to the second resonator conductor layer. [Effects of the Invention]

[0012] In the multilayer filter device of the present invention, the first resonator conductor layer extends in a first direction away from at least one through hole, and the second resonator conductor layer extends in a second direction away from at least one through hole. The at least one through hole is electrically connected to a ground conductor layer, and the ground conductor layer is electrically connected to ground. This makes it possible to realize a multilayer filter device that can suppress changes in characteristics due to manufacturing variations. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a circuit diagram showing a circuit configuration of a multilayer filter device according to a first embodiment of the present invention. [Figure 2] 1 is a perspective view showing the appearance of a multilayer filter device according to a first embodiment of the present invention. [Figure 3] 1 is an explanatory view showing a pattern-formed surface of a first dielectric layer in a laminate of a multilayer filter device according to a first embodiment of the present invention. FIG. [Figure 4]3 is an explanatory view showing the pattern-forming surfaces of the second to seventh dielectric layers in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 5] 3 is an explanatory view showing a pattern-formed surface of an eighth dielectric layer in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 6] 3 is an explanatory view showing a pattern-formed surface of a ninth dielectric layer in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 7] 3 is an explanatory view showing a pattern-formed surface of a tenth dielectric layer in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 8] 3 is an explanatory view showing the pattern-forming surfaces of the 11th to 16th dielectric layers in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 9] 3 is an explanatory view showing a terminal formation surface of a sixteenth dielectric layer in the laminate of the multilayer filter device according to the first embodiment of the present invention. FIG. [Figure 10] 1 is a perspective view showing the inside of a laminate of a multilayer filter device according to a first embodiment of the present invention. [Figure 11] FIG. 10 is an explanatory diagram schematically showing the configuration of a multilayer filter device according to a second embodiment of the present invention. [Figure 12] FIG. 10 is an explanatory view schematically showing the configuration of a modified example of the multilayer filter device according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, with reference to Fig. 1, an outline of the configuration of a multilayer filter device (hereinafter simply referred to as a filter device) 1 according to a first embodiment of the present invention will be described. The filter device 1 includes two ports 3 and 4, a first resonant circuit 10, and a second resonant circuit 20. Each of the ports 3 and 4 is a port for inputting or outputting a signal.

[0015] In this embodiment, the first resonant circuit 10 constitutes a band-pass filter, and the second resonant circuit 20 constitutes a band elimination filter. In this embodiment, particularly, the first resonant circuit 10 is a main resonant circuit, and the second resonant circuit 20 is a secondary resonant circuit. The filter device 1 as a whole functions as a band-pass filter.

[0016] In terms of the circuit configuration, the first resonant circuit 10 is provided between the two ports 3 and 4. The first resonant circuit 10 is also coupled to both of the two ports 3 and 4. In this application, the expression "in terms of the circuit configuration" is used to refer to the arrangement on a circuit diagram, not the arrangement in a physical configuration.

[0017] The second resonant circuit 20 is provided between the two ports 3 and 4 in terms of the circuit configuration. The second resonant circuit 20 is coupled to at least one of the two ports 3 and 4. In particular, in this embodiment, the second resonant circuit 20 is coupled to both of the two ports 3 and 4. In this embodiment, the second resonant circuit 20 is provided in parallel to the first resonant circuit 10 between the two ports 3 and 4 in terms of the circuit configuration, and is not provided between the first resonant circuit 10 and port 3 or port 4.

[0018] The filter device 1 further includes two first capacitors C11 and C12 that capacitively couple the first resonant circuit 10 to the two ports 3 and 4. The first capacitor C11 capacitively couples the first resonant circuit 10 to the port 3. The first capacitor C12 capacitively couples the first resonant circuit 10 to the port 4.

[0019] The filter device 1 further includes at least one second capacitor that capacitively couples the second resonant circuit 20 with the two ports 3 and 4. In particular, in this embodiment, the filter device 1 includes two second capacitors C21 and C22 as the at least one second capacitor. The second capacitor C21 capacitively couples the second resonant circuit 20 with the port 3. The second capacitor C22 capacitively couples the second resonant circuit 20 with the port 4.

[0020] The coupling between the second resonant circuit 20 and the two ports 3 and 4 is weaker than the coupling between the first resonant circuit 10 and the two ports 3 and 4. When the coupling between the resonant circuit and the ports is capacitive, as in this embodiment, the coupling becomes stronger as the capacitance of the capacitor that capacitively couples the resonant circuit and the ports increases. In other words, the coupling between the resonant circuit and the ports becomes weaker as the capacitance decreases.

[0021] In this embodiment, the capacitance of each of the second capacitors C21 and C22 is smaller than the capacitance of each of the first capacitors C11 and C12. As a result, the coupling between the second resonant circuit 20 and port 3 and between the second resonant circuit 20 and port 4 are weaker than the coupling between the first resonant circuit 10 and port 3 and between the first resonant circuit 10 and port 4. In one example, the capacitance of each of the second capacitors C21 and C22 is 0.03 pF, and the capacitance of each of the first capacitors C11 and C12 is 0.14 pF.

[0022] The first resonant circuit 10 may be directly connected to each of ports 3 and 4. When the resonant circuit and the port are directly connected, in the high frequency range, this is essentially the same as when the resonant circuit and the port are capacitively coupled by an infinite capacitance. Therefore, in this case, the coupling between the first resonant circuit 10 and port 3 and between the first resonant circuit 10 and port 4 is stronger than when the first resonant circuit and the port are capacitively coupled by the first capacitors C11 and C12.

[0023] Next, an example of the configuration of the first and second resonant circuits 10, 20 will be described with reference to FIG. 1. First, the first resonant circuit 10 will be described. The first resonant circuit 10 includes a plurality of first resonators. In this embodiment, the first resonant circuit 10 particularly includes two first resonators 11, 12 arranged in this order from the port 3 side in the circuit configuration as the plurality of first resonators. Each of the first resonators 11, 12 is a quarter-wave resonator with one end short-circuited and the other end open. The first resonators 11, 12 are magnetically coupled to each other.

[0024] The first resonator 11 is coupled to port 3. The first resonator 11 has a first end 11a closest to port 3 and a second end 11b farthest from port 3. The first capacitor C11 is provided between the first end 11a of the first resonator 11 and port 3 in the circuit configuration.

[0025] The first resonator 12 is coupled to port 4. The first resonator 12 has a first end 12a closest to port 4 and a second end 12b farthest from port 4. The first capacitor C12 is provided in the circuit configuration between the first end 12a of the first resonator 12 and port 4.

[0026] The second end 11b of the first resonator 11 and the second end 12b of the first resonator 12 are each connected to ground. In Fig. 1, symbol L11 denotes an inductance component of a line connecting the first resonators 11 and 12 to ground.

[0027] Next, the second resonant circuit 20 will be described. The second resonant circuit 20 includes a plurality of second resonators. In particular, in this embodiment, the second resonant circuit 20 includes, as the plurality of second resonators, two second resonators 21 and 22 arranged in this order from the port 3 side in the circuit configuration. Each of the second resonators 21 and 22 is a half-wavelength resonator with both ends open. The second resonators 21 and 22 are magnetically coupled to each other.

[0028] The second resonator 21 is coupled to port 3. The second resonator 21 has a first end 21a closest to port 3 and a second end 21b farthest from port 3. The second capacitor C21 is provided between the first end 21a of the second resonator 21 and port 3 in terms of the circuit configuration.

[0029] The second resonator 22 is coupled to port 4. The second resonator 22 has a first end 22a closest to port 4 and a second end 22b farthest from port 4. A second capacitor C22 is provided in the circuit configuration between the first end 22a of the second resonator 22 and port 4.

[0030] Next, other configurations of the filter device 1 will be described with reference to Fig. 2. Fig. 2 is a perspective view showing the appearance of the filter device 1.

[0031] The filter device 1 further includes a laminate 50. The laminate 50 includes a plurality of stacked dielectric layers, and a plurality of conductor layers and a plurality of through holes formed in the plurality of dielectric layers. The ports 3 and 4, the first resonant circuit 10, the second resonant circuit 20, the first capacitors C11 and C12, and the second capacitors C21 and C22 are integrated into the laminate 50.

[0032] The laminate 50 has a bottom surface 50A and a top surface 50B located at both ends in the stacking direction T of the multiple dielectric layers, and four side surfaces 50C to 50F connecting the bottom surface 50A and the top surface 50B. The side surfaces 50C and 50D face in opposite directions from each other, and the side surfaces 50E and 50F also face in opposite directions from each other. The side surfaces 50C to 50F are perpendicular to the top surface 50B and the bottom surface 50A.

[0033] Here, the X direction, Y direction, and Z direction are defined as shown in FIG. 2. The X direction, Y direction, and Z direction are perpendicular to each other. In this embodiment, a direction parallel to the stacking direction T is defined as the Z direction. Furthermore, the direction opposite to the X direction is defined as the −X direction, the direction opposite to the Y direction is defined as the −Y direction, and the direction opposite to the Z direction is defined as the −Z direction.

[0034] As shown in FIG. 2, the bottom surface 50A is located at the end of the stack 50 in the -Z direction. The top surface 50B is located at the end of the stack 50 in the Z direction. The side surface 50C is located at the end of the stack 50 in the -X direction. The side surface 50D is located at the end of the stack 50 in the X direction. The side surface 50E is located at the end of the stack 50 in the -Y direction. The side surface 50F is located at the end of the stack 50 in the Y direction.

[0035] The filter device 1 further includes terminals 511 and 661 and ground conductor layers 512 and 662. The terminal 511 and the ground conductor layer 512 are arranged on the bottom surface 50A. In particular, in this embodiment, the ground conductor layer 512 covers almost the entire bottom surface 50A. A gap is formed between the terminal 511 and the ground conductor layer 512.

[0036] Terminal 661 and ground conductor layer 662 are disposed on top surface 50B. In particular, in this embodiment, ground conductor layer 662 covers almost the entire top surface 50B. A gap is formed between terminal 661 and ground conductor layer 662.

[0037] Terminal 511 corresponds to port 3, and terminal 661 corresponds to port 4. Each of the ground conductor layers 512 and 662 is connected to ground.

[0038] Next, an example of the plurality of dielectric layers and the plurality of conductor layers constituting the laminate 50 will be described with reference to Figures 3 to 9. In this example, the laminate 50 has 16 laminated dielectric layers. Hereinafter, these 16 dielectric layers will be referred to as the first to sixteenth dielectric layers, in order from the bottom up. The first to sixteenth dielectric layers will be represented by reference numerals 51 to 66. In Figures 3 to 9, the plurality of circles represent the plurality of through holes.

[0039] 3 shows the pattern formation surface of the first dielectric layer 51. A terminal 511 and a ground conductor layer 512 are formed on the pattern formation surface of the dielectric layer 51. A specific through hole 51T1 connected to the terminal 511 is also formed in the dielectric layer 51. The multiple through holes formed in the dielectric layer 51 except for the specific through hole 51T1 are connected to the ground conductor layer 512. The multiple through holes connected to the ground conductor layer 512 include specific through holes 51T2 and 51T3.

[0040] 4 shows the pattern-forming surfaces of the second to seventh dielectric layers 52 to 57. Specific through holes 52T1, 52T2, and 52T3 are formed in each of the dielectric layers 52 to 57. Specific through holes 51T1 to 51T3 formed in the dielectric layer 51 are connected to specific through holes 52T1 to 52T3 formed in the dielectric layer 52, respectively. Furthermore, in the dielectric layers 52 to 57, adjacent through holes with the same reference numerals are connected to each other.

[0041] 5 shows the pattern-formed surface of the eighth dielectric layer 58. Conductor layers 581 and 582 are formed on the pattern-formed surface of the dielectric layer 58. Specific through-holes 58T1, 58T2, and 58T3 are also formed in the dielectric layer 58. Specific through-holes 52T1 to 52T3 formed in the dielectric layer 57 are connected to specific through-holes 58T1 to 58T3, respectively.

[0042] 6 shows the pattern formation surface of the ninth dielectric layer 59. Resonator conductor layers 591, 592, 593, and 594, conductor layers 595 and 596, and a ground conductor layer 597 are formed on the pattern formation surface of the dielectric layer 59. Each of the conductor layers 591 to 596 has a first end and a second end located opposite to each other.

[0043] Each of the conductor layers 591 and 595 extends in the −X direction from the first end to the second end, each of the conductor layers 592 and 596 extends in the X direction from the first end to the second end, and each of the conductor layers 593 and 594 extends in the −Y direction from the first end to the second end.

[0044] Furthermore, specific through holes 59T1, 59T2, and 59T3 are formed in the dielectric layer 59. The specific through hole 59T1 is connected to a portion of the conductor layer 596 near a first end. The specific through hole 58T1 formed in the dielectric layer 58 is connected to a portion of the conductor layer 595 near a first end. The specific through holes 58T2 and 58T3 formed in the dielectric layer 58 and the specific through holes 59T2 and 59T3 are connected to a ground conductor layer 597.

[0045] A portion of conductor layer 591 near its first end is adjacent to, and spaced a predetermined distance from, a portion of conductor layer 595 near its second end. A portion of conductor layer 592 near its first end is adjacent to, and spaced a predetermined distance from, a portion of conductor layer 596 near its second end. The second ends of conductor layers 591 and 592 are connected to ground conductor layer 597. In FIG. 6, the boundaries between conductor layers 591 and 592 and ground conductor layer 597 are indicated by dotted lines.

[0046] A first end of conductor layer 593 is adjacent to, and spaced a predetermined distance from, a portion of conductor layer 595 near the second end. A first end of conductor layer 594 is adjacent to, and spaced a predetermined distance from, a portion of conductor layer 596 near the second end.

[0047] 7 shows the pattern-formed surface of the tenth dielectric layer 60. Conductor layers 601 and 602 are formed on the pattern-formed surface of the dielectric layer 60. Specific through-holes 60T1, 60T2, and 60T3 are also formed in the dielectric layer 60. Specific through-holes 59T1 to 59T3 formed in the dielectric layer 59 are connected to specific through-holes 60T1 to 60T3, respectively.

[0048] 8 shows the pattern-forming surfaces of the eleventh to sixteenth dielectric layers 61 to 66. Specific through-holes 61T1, 61T2, and 61T3 are formed in each of the dielectric layers 61 to 66. Specific through-holes 60T1 to 60T3 formed in the dielectric layer 60 are connected to specific through-holes 61T1 to 61T3 formed in the dielectric layer 61, respectively. Furthermore, in the dielectric layers 61 to 66, adjacent through-holes with the same reference numerals are connected to each other.

[0049] 9 shows the terminal formation surface, which is the surface opposite to the pattern formation surface of the 16th dielectric layer 66. A terminal 661 and a ground conductor layer 662 are formed on the terminal formation surface of the dielectric layer 66. A specific through hole 61T1 formed in the dielectric layer 66 is connected to the terminal 661. The multiple through holes (excluding the specific through hole 61T1) formed in the dielectric layer 66, including specific through holes 61T2 and 61T3 formed in the dielectric layer 66, are connected to the ground conductor layer 662.

[0050] The laminate 50 shown in Figure 2 is constructed by stacking the first to sixteenth dielectric layers 51 to 66 so that the pattern-forming surface of the first dielectric layer 51 becomes the bottom surface 50A of the laminate 50 and the terminal-forming surface of the sixteenth dielectric layer 66 becomes the top surface 50B of the laminate 50.

[0051] FIG. 10 shows the inside of the laminate 50, which is formed by stacking the first through sixteenth dielectric layers 51 to 66. As shown in FIG. 10, the inside of the laminate 50 has the multiple conductor layers and multiple through holes shown in FIGS. 3 to 9 stacked therein. The conductor layer 595 is connected to the terminal 511 via specific through holes 51T1, 52T1, and 58T1. The conductor layer 596 is connected to the terminal 661 via specific through holes 59T1, 60T1, and 61T1. The ground conductor layers 512, 597, and 662 are connected to each other by multiple through holes excluding the specific through holes 51T1, 52T1, 58T1, 59T1, 60T1, and 61T1. In particular, the ground conductor layer 597 is connected to the ground conductor layer 512 via specific through holes 51T2, 51T3, 52T2, 52T3, 58T2, and 58T3, and is connected to the ground conductor layer 662 via specific through holes 59T2, 59T3, 60T2, 60T3, 61T2, and 61T3.

[0052] The following describes the correspondence between the components of the filter device 1 shown in Fig. 1 and the internal components of the laminate 50 shown in Figs. 4 to 8. The first resonator 11 of the first resonant circuit 10 is formed by a resonator conductor layer 591. The first resonator 12 of the first resonant circuit 10 is formed by a resonator conductor layer 592. The second resonator 21 of the second resonant circuit 20 is formed by a resonator conductor layer 593. The second resonator 22 of the second resonant circuit 20 is formed by a resonator conductor layer 594.

[0053] The first capacitor C11 is formed by conductor layers 581, 591, and 595 and a dielectric layer 58 between these conductor layers. The first capacitor C12 is formed by conductor layers 582, 592, and 596 and a dielectric layer 58 between these conductor layers. The second capacitor C21 is formed by conductor layers 593, 595, and 601 and a dielectric layer 59 between these conductor layers. The second capacitor C22 is formed by conductor layers 594, 596, and 602 and a dielectric layer 59 between these conductor layers.

[0054] Next, a brief description will be given of structural features of the filter device 1 according to the present embodiment. In the filter device 1, the conductor layers 591 to 594 for resonators are provided in a space surrounded by the conductor layers 512 and 662 for grounding and a plurality of through holes.

[0055] In the filter device 1, the area of each of the conductor layers 601 and 602 that form the second capacitors C21 and C22 is smaller than the area of each of the conductor layers 581 and 582 that form the first capacitors C11 and C12.

[0056] The specific through holes 51T2, 51T3, 52T2, 52T3, 58T2, 58T3, 59T2, 59T3, 60T2, 60T3, 61T2, and 61T3 are electrically connected to the ground conductor layers 512, 597, and 662. The ground conductor layers 512, 597, and 662 are electrically connected to the ground. Hereinafter, the specific through holes 51T2, 51T3, 52T2, 52T3, 58T2, 58T3, 59T2, 59T3, 60T2, 60T3, 61T2, and 61T3 will be referred to as the multiple specific through holes connected to the ground.

[0057] The plurality of specific through holes connected to ground include two through holes aligned along a direction perpendicular to the stacking direction T. Specifically, these two through holes are a pair of specific through holes 71T2 and 71T3, a pair of specific through holes 72T2 and 72T3, a pair of specific through holes 78T2 and 78T3, a pair of specific through holes 79T2 and 79T3, a pair of specific through holes 80T2 and 80T3, and a pair of specific through holes 81T2 and 81T3. The two specific through holes included in these pairs are aligned along a direction perpendicular to at least one of the directions in which a resonator conductor layer 591 (described later) extends and the directions in which a resonator conductor layer 592 extends. In this embodiment, the two specific through holes included in these pairs are aligned along a direction parallel to the Y direction.

[0058] The resonator conductor layer 591 extends in a first direction away from the plurality of specific through holes connected to ground. The resonator conductor layer 591 extends in a second direction away from the plurality of specific through holes connected to ground. In this embodiment in particular, each of the resonator conductor layers 591 and 592 is electrically connected to the plurality of specific through holes connected to ground.

[0059] The first and second directions are directions perpendicular to the stacking direction T. In this embodiment, the first direction is the X direction and the second direction is the −X direction. Therefore, the first direction and the second direction are opposite to each other.

[0060] Each of the resonator conductor layers 593 and 594 includes a narrow portion and two wide portions located on both sides of the narrow portion. The second resonators 21 and 22 formed by the resonator conductor layers 593 and 594 are both stepped impedance resonators.

[0061] Next, the operation and effects of the filter device 1 according to this embodiment will be described. In this embodiment, as described above, each of the resonator conductor layers 591, 592 extends in a direction away from the plurality of specific through holes connected to ground. Therefore, in this embodiment, if the resonator conductor layers 591, 592 or the connected plurality of specific through holes are misaligned in a direction parallel to the X direction due to manufacturing variations, one of the resonator conductor layers 591, 592 becomes longer and the other becomes shorter. This allows this embodiment to offset changes in the resonator characteristics caused by changes in the length of the resonator conductor layers. As a result, this embodiment allows for suppressing changes in the characteristics of the first resonator circuit 10, i.e., the bandpass filter, caused by manufacturing variations.

[0062] Furthermore, in this embodiment, as described above, the plurality of specific through holes connected to ground include two through holes aligned along a direction orthogonal to the stacking direction T and orthogonal to at least one of the extending directions of the resonator conductor layer 591 and the resonator conductor layer 592. In this embodiment, the two through holes are aligned along a direction orthogonal to both the extending direction of the resonator conductor layer 591 and the extending direction of the resonator conductor layer 592. Therefore, even if the resonator conductor layers 591 and 592 or the plurality of connected specific through holes are misaligned in a direction parallel to the Y direction, the lengths of the resonator conductor layers 591 and 592 hardly change. This also makes it possible, according to this embodiment, to suppress changes in the characteristics of the first resonator circuit 10, i.e., the bandpass filter, due to manufacturing variations.

[0063] The above-described effects of the present embodiment will be described below with reference to the results of a simulation. In the simulation, a model of an example and a model of a comparative example were used. Both the model of the example and the model of the comparative example are bandpass filter models including a ground conductor layer and two resonator conductor layers extending from the ground conductor layer.

[0064] In the model of the example, similar to the filter device 1 according to the present embodiment, the two resonator conductor layers are arranged to sandwich the ground conductor layer and extend in opposite directions. In the model of the comparative example, the two resonator conductor layers extend in the same direction from the ground conductor layer. In the simulation, the longitudinal direction (direction parallel to the extending direction) of the resonator conductor layers was set to the same direction in the model of the example and the model of the comparative example. In the simulation, the length of each of the two resonator conductor layers in the model of the example was set to 700 μm, and the length of each of the two resonator conductor layers in the model of the comparative example was set to 855 μm.

[0065] In the simulation, the shift amount of the lower cutoff frequency, which is the lower limit of the passband, and the shift amount of the upper cutoff frequency, which is the upper limit of the passband, were calculated when two resonator conductor layers were shifted by 15 μm in the longitudinal direction of the resonator conductor layers. In the model of the example, when two resonator conductor layers were shifted by 15 μm in the longitudinal direction of the resonator conductor layers, one of the two resonator conductor layers became shorter by 15 μm and the other became longer by 15 μm. In the model of the comparative example, when two resonator conductor layers were shifted by 15 μm in the longitudinal direction of the resonator conductor layers, both of the two resonator conductor layers became shorter or longer by 15 μm. In the simulation, the two resonator conductor layers were shifted so that both of the two resonator conductor layers became longer.

[0066] When the two resonator conductor layers are shifted as described above, the deviation of the lower cutoff frequency in the comparative example model is 0.80% and the deviation of the upper cutoff frequency is 1.25%. Furthermore, the deviation of the lower cutoff frequency in the example model is 0.11% and the deviation of the upper cutoff frequency is 0.11%. As can be seen from the simulation results, this embodiment can suppress variations in the lower cutoff frequency and the upper cutoff frequency due to manufacturing variations.

[0067] Next, other effects of the filter device 1 in this embodiment will be described. As described above, in this embodiment, the coupling between the second resonant circuit 20 and the two ports 3 and 4 is weaker than the coupling between the first resonant circuit 10 and the two ports 3 and 4. As a result, according to this embodiment, the second resonant circuit 20 can be incorporated into the filter device 1 while suppressing the effect of the second resonant circuit 20.

[0068] In particular, in this embodiment, the first resonant circuit 10 constitutes a band-pass filter, and the second resonant circuit 20 constitutes a band-elimination filter. Specifically, the effect of the second resonant circuit 20 is to increase the insertion loss in a frequency range near the center frequency of the stop band of the band-elimination filter formed by the second resonant circuit 20 in the frequency characteristics of the insertion loss of the filter device 1 (frequency characteristics of the insertion loss of the band-pass filter). Therefore, according to this embodiment, the second resonant circuit 20 can be incorporated into the filter device 1 while reducing the insertion loss in the above frequency range to a required level. Therefore, according to this embodiment, by setting the center frequency of the stop band of the band-elimination filter formed by the second resonant circuit 20 to a frequency close to the pass band of the band-pass filter formed by the first resonant circuit 10, it is possible to obtain a characteristic in which the insertion loss changes sharply in a frequency range close to the pass band of the filter device 1 while suppressing an increase in the insertion loss in the pass band of the filter device 1.

[0069] Increasing the number of resonators constituting the bandpass filter can also achieve a characteristic in which the insertion loss changes sharply in the frequency range close to the passband. However, when comparing resonators with the same Q value, the problem arises that the insertion loss in the passband increases as the number of resonators increases.

[0070] In contrast, in this embodiment, the first resonant circuit 10 includes only two resonators. According to this embodiment, it is possible to obtain a characteristic in which the insertion loss changes sharply in a frequency range close to the pass band without increasing the number of resonators constituting the bandpass filter. As a result, according to this embodiment, it is possible to suppress an increase in the insertion loss in the pass band. Furthermore, according to this embodiment, it is possible to reduce the size of the filter device 1.

[0071] The center frequency of the stopband of the band elimination filter formed by the second resonant circuit 20 may be in the frequency range on the lower side of the passband of the bandpass filter formed by the first resonant circuit 10, or may be in the frequency range on the higher side of the passband.

[0072] [Second embodiment] Next, a second embodiment of the present invention will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram that schematically shows the configuration of a filter device 101 according to this embodiment.

[0073] The filter device 101 according to this embodiment is a bandpass filter including four resonators 31, 32, 33, and 34. Each of the resonators 31 to 34 is a quarter-wave resonator with one end shorted and the other end open, and is formed by a resonator conductor layer extending in one direction. In the following description, the term "resonator" refers to at least one of the resonator and the resonator conductor layer.

[0074] The filter device 101 further includes ground conductors 41, 42, and 43, each electrically connected to the ground. Each of the ground conductors 41 to 43 includes a ground conductor layer electrically connected to the ground and at least one through-hole electrically connected to the ground conductor layer. Each of the ground conductors 41 to 43 extends in a direction parallel to the Y direction as a whole.

[0075] One end of the resonator 31 is connected to the ground conductor 41. The resonator 31 extends from the ground conductor 41 in the X direction.

[0076] The resonators 32 and 33 are arranged on either side of the ground conductor 42. One end of each of the resonators 32 and 33 is connected to the ground conductor 42. The resonator 32 extends in the −X direction from the ground conductor 42. The resonator 33 extends in the X direction from the ground conductor 42.

[0077] One end of the resonator 34 is connected to the ground conductor 43. The resonator 34 extends from the ground conductor 43 in the −X direction.

[0078] The resonator 31 is electromagnetically coupled to the resonator 32, the resonator 32 is electromagnetically coupled to the resonator 31, and the resonator 33 is electromagnetically coupled to the resonator .

[0079] In this embodiment, the other end of the resonator 34 faces the other end of the resonator 31 .

[0080] In this embodiment, if the resonators 32, 33 or the ground conductor 42 are misaligned in a direction parallel to the X direction due to manufacturing variations, one of the resonators 32, 33 becomes longer and the other becomes shorter. Similarly, if the resonators 31, 34 or the ground conductor 41, 43 are misaligned in a direction parallel to the X direction due to manufacturing variations, one of the resonators 31, 34 becomes longer and the other becomes shorter. For these reasons, this embodiment can cancel out changes in the characteristics of the resonators 31 to 34. As a result, this embodiment can suppress changes in the characteristics of the filter device 101 caused by manufacturing variations.

[0081] Furthermore, in this embodiment, each of the ground conductors 41 to 43 extends in a direction parallel to the Y direction as a whole. Therefore, even if the resonators 31 to 34 or the ground conductors 41 to 43 are shifted in a direction parallel to the Y direction, the length of each of the resonators 31 to 34 hardly changes. This also makes it possible to suppress changes in the characteristics of the filter device 101 caused by manufacturing variations.

[0082] [Variations] Next, a modified example of the filter device 101 according to the present embodiment will be described with reference to Fig. 12. Fig. 12 is an explanatory diagram schematically illustrating the configuration of a modified example of the filter device 101 according to the present embodiment. In this modified example, a ground conductor 42 is interposed between the resonator 31 and the resonator 34.

[0083] Other configurations, actions, and effects of this embodiment are the same as those of the first embodiment.

[0084] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, the number and configuration of each of the first and second resonators are not limited to those described in the embodiments, and may be any number that satisfies the scope of the claims. The number of each of the first and second resonators may be three or more.

[0085] Furthermore, the first resonant circuit 10 is not limited to a band-pass filter, and may also constitute other filters such as a low-pass filter or a high-pass filter.

[0086] Furthermore, the first direction is not limited to the X direction, but may be a direction tilted from the X direction toward the Y direction or the -Y direction. Similarly, the second direction is not limited to the -X direction, but may be a direction tilted from the -X direction toward the Y direction or the -Y direction. Furthermore, the angle between the first direction and the second direction may be greater than 90° and less than 180°. [Explanation of symbols]

[0087] 1...filter device, 3,4...port, 10...first resonant circuit, 11,12...first resonator, 20...second resonant circuit, 21,22...second resonator, 50...laminated body, 51-66...dielectric layer, 511,661...terminal, 512,597,662...ground conductor layer, C11,C12...first capacitor, C21,C22...second capacitor.

Claims

1. a ground conductor layer electrically connected to the ground; at least one through hole electrically connected to the ground conductor layer; a first resonator conductor layer and a second resonator conductor layer disposed so as to sandwich the ground conductor layer; a laminate including a plurality of laminated dielectric layers, the laminate being configured to integrate the ground conductor layer, the at least one through hole, the first resonator conductor layer, and the second resonator conductor layer; the first resonator conductor layer extends along a first direction away from the at least one through hole; the second resonator conductor layer extends along a second direction away from the at least one through hole; a first end of the first resonator conductor layer and a second resonator conductor layer connected to the ground conductor layer;

2. A ground conductor layer electrically connected to the ground; at least one through hole electrically connected to the ground conductor layer; a first resonator conductor layer and a second resonator conductor layer disposed so as to sandwich the ground conductor layer; a laminate including a plurality of laminated dielectric layers, the laminate being configured to integrate the ground conductor layer, the at least one through hole, the first resonator conductor layer, and the second resonator conductor layer; the first resonator conductor layer extends along a first direction away from the at least one through hole; the second resonator conductor layer extends along a second direction away from the at least one through hole; The multilayer filter device according to claim 1, wherein each of the first resonator conductor layer and the second resonator conductor layer constitutes a resonator having one end short-circuited and the other end open.

3. 3. The multilayer filter device according to claim 2, wherein each of the first resonator conductor layer and the second resonator conductor layer is electrically connected to the at least one through hole.

4. 4. The multilayer filter device according to claim 1, wherein the at least one through hole includes a plurality of through holes arranged along a direction orthogonal to the stacking direction of the plurality of dielectric layers and orthogonal to at least one of the first direction and the second direction.

5. 5. The multilayer filter device according to claim 1, wherein the first direction and the second direction are opposite to each other.

6. a third resonator conductor layer coupled to the first resonator conductor layer; 6. The multilayer filter device according to claim 1, further comprising a fourth resonator conductor layer coupled to the second resonator conductor layer.

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