Layered filter device

Abstract

To achieve a laminated filter device enabling a stub type resonator to be added thereto without increasing the size.SOLUTION: A laminated filter device 1 comprises: a laminate 50; an input terminal 2 and an output terminal 3 which are arranged on a bottom face 50A of the laminate 50; and a resonance circuit 10, capacitors C21 and C22, a first stub type resonator 21, and a second stub type resonator 22 which are arranged in the laminate 50. The resonance circuit 10 is provided on a first path 5. The capacitors C21 and C22 are provided in a second path 6. The first stub type resonator 21 is provided between the input terminal 2 and the capacitor C21 in the second path 6. The second stub type resonator 22 is provided between the output terminal 3 and the capacitor C22 in the second path 6.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multilayer filter device including a plurality of resonators and a stub-type resonator. [Background technology]

[0002] Bandpass filters are one type of electronic component used in communication devices. Bandpass filters used in small communication devices in particular require miniaturization. Known bandpass filters suitable for miniaturization include those that use a laminate including multiple dielectric layers and multiple conductor layers stacked together.

[0003] Currently, communication services using fifth-generation mobile communication systems (hereinafter referred to as 5G) are beginning to be provided. 5G is expected to use frequency bands above 10 GHz, particularly the quasi-millimeter wave band of 10 to 30 GHz and the millimeter wave band of 30 to 300 GHz. As higher frequency bands than conventional ones are used, bandpass filters are also required to satisfy characteristics in higher frequency bands than conventional ones. For example, there is a demand to increase the pass attenuation of bandpass filters on the high-frequency side of their passbands.

[0004] Patent Document 1 discloses a bandpass filter having a laminate including a plurality of stacked dielectric layers. This bandpass filter has an input terminal, an output terminal, three resonators provided on a path connecting the input terminal and the output terminal, and a capacitor provided on another path connecting the input terminal and the output terminal that does not pass through the three resonators.

[0005] Patent Document 2 discloses a bandpass filter having a notch filter section for attenuating signals with a predetermined frequency higher than the passband. The notch filter section includes a quarter-wave resonator. This quarter-wave resonator is a stub-type resonator with one end connected to an input / output port and the other end open. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-124211 [Patent Document 2] Japanese Patent Application Publication No. 2020-057920 Summary of the Invention [Problem to be solved by the invention]

[0007] In a laminated bandpass filter using a laminate, antiresonance may occur at the high-frequency side of the passband, depending on the structure of the laminate, resulting in a small amount of attenuation. To address this issue, it is possible to use a stub-type resonator, as disclosed in Patent Document 2. That is, by adding a stub-type resonator that forms an attenuation pole near the frequency at which antiresonance occurs to the bandpass filter, it is possible to increase the amount of attenuation at the high-frequency side of the passband. However, adding a stub-type resonator poses a problem in that it becomes difficult to miniaturize the bandpass filter.

[0008] The above problem is not limited to multilayer bandpass filters, but applies to all multilayer filter devices that include a resonant circuit that functions as a filter.

[0009] 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 to which a stub-type resonator can be added without increasing the size. [Means for solving the problem]

[0010] The multilayer filter device of the present invention comprises a laminate including a plurality of laminated dielectric layers and having a first surface facing a substrate and a second surface opposite the first surface, an input terminal and an output terminal arranged on the first surface, and a resonant circuit, a capacitor, a first stub-type resonator, and a second stub-type resonator arranged within the laminate. The resonant circuit is arranged in a first path connecting the input terminal and the output terminal in terms of the circuit configuration. The capacitor is arranged in a second path connecting the input terminal and the output terminal and not passing through the resonant circuit in terms of the circuit configuration. The first stub-type resonator is arranged in the second path between the input terminal and the capacitor in terms of the circuit configuration. The second stub-type resonator is arranged in the second path between the output terminal and the capacitor in terms of the circuit configuration.

[0011] The multilayer filter device of the present invention may further include a ground conductor layer integrated with the laminate and connected to ground. The resonant circuit, the capacitor, the first stub-type resonator, and the second stub-type resonator may be located between the first surface and the ground conductor layer in the stacking direction of the multiple dielectric layers, but may not be located between the second surface and the ground conductor layer.

[0012] In addition, in the multilayer filter device of the present invention, at least some of the elements constituting the resonant circuit may be arranged between the first and second stub-type resonators and the ground conductor layer in the stacking direction of the multiple dielectric layers.

[0013] In the multilayer filter device of the present invention, at least one of the first stub-type resonator and the second stub-type resonator may have an electrical length equivalent to ¼ of the wavelength corresponding to the predetermined frequency.

[0014] In the multilayer filter device of the present invention, the physical length of the first stub resonator and the physical length of the second stub resonator may be equal to each other.

[0015] In addition, in the multilayer filter device of the present invention, the shape and arrangement of the first stub-type resonator and the shape and arrangement of the second stub-type resonator may be symmetrical with respect to a virtual plane that passes between the first stub-type resonator and the second stub-type resonator and is parallel to the stacking direction of the multiple dielectric layers.

[0016] In the multilayer filter device of the present invention, the first stub resonator and the second stub resonator may be disposed at the same position in the lamination direction of the plurality of dielectric layers.

[0017] In the multilayer filter device of the present invention, the capacitor may include a capacitor conductor layer. The capacitor conductor layer may be disposed at a position different from the first and second stub resonators in the stacking direction of the dielectric layers. The capacitor conductor layer may face a portion near one end of the first stub resonator and a portion near one end of the second stub resonator. [Effects of the Invention]

[0018] In the multilayer filter device of the present invention, the first stub-type resonator is provided between the input terminal and the capacitor in the second path, and the second stub-type resonator is provided between the output terminal and the capacitor in the second path, thereby achieving the effect of realizing a multilayer filter device to which stub-type resonators are added without increasing the size. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a circuit diagram showing a circuit configuration of a multilayer filter device according to an embodiment of the present invention. [Figure 2] 1 is a perspective view showing the appearance of a multilayer filter device according to an embodiment of the present invention. [Figure 3] 1 is an explanatory diagram showing pattern-formed surfaces of first to third dielectric layers in a laminate of a multilayer filter device according to an embodiment of the present invention. FIG. [Figure 4]3 is an explanatory diagram showing pattern-formed surfaces of the fourth to seventh dielectric layers in the laminate of the multilayer filter device according to one embodiment of the present invention. FIG. [Figure 5] 3 is an explanatory diagram showing pattern-forming surfaces of eighth to tenth dielectric layers in a laminate of a multilayer filter device according to an embodiment of the present invention. FIG. [Figure 6] 3 is an explanatory diagram showing a pattern-forming surface of an eleventh dielectric layer in a laminate of a multilayer filter device according to an embodiment of the present invention. FIG. [Figure 7] 1 is a perspective view showing the inside of a laminate of a multilayer filter device according to an embodiment of the present invention. [Figure 8] FIG. 8 is a perspective view showing a part of the inside of the laminate shown in FIG. 7. [Figure 9] 8 is a plan view showing a part of the inside of the laminate shown in FIG. 7. FIG. [Figure 10] FIG. 10 is a plan view showing a part of the inside of a laminate in a modified example of the multilayer filter device according to the embodiment of the present invention. [Figure 11] FIG. 10 is a plan view showing a part of the inside of a laminate in a multilayer filter device of a comparative example. [Figure 12] FIG. 10 is a characteristic diagram showing attenuation characteristics obtained by simulation. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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 an embodiment of the present invention will be described. FIG. 1 shows a bandpass filter as an example of the filter device 1. The filter device 1 includes an input terminal 2, an output terminal 3, and a resonant circuit 10. Each of the input terminal 2 and the output terminal 3 is a terminal for inputting or outputting a signal. The resonant circuit 10 constitutes a main part of the bandpass filter.

[0021] In terms of the circuit configuration, the resonant circuit 10 is provided on a first path 5 connecting the input terminal 2 and the output terminal 3. In this embodiment, the resonant circuit 10 includes two LC resonators 11 and 12. In terms of the circuit configuration, the LC resonators 11 and 12 are arranged in this order from the input terminal 2 side. Note that 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.

[0022] The LC resonator 11 includes an inductor L11 and a capacitor C11. The LC resonator 12 includes an inductor L12 and a capacitor C12. The inductors L11 and L12 are configured to be magnetically coupled. The resonant circuit 10 further includes a capacitor C10 that capacitively couples the inductors L11 and L12.

[0023] The filter device 1 further includes capacitors C21 and C22, a first stub-type resonator 21, and a second stub-type resonator 22. In terms of the circuit configuration, the capacitors C21 and C22 are provided on a second path 6 that connects the input terminal 2 and the output terminal 3 and does not pass through the resonant circuit 10. In terms of the circuit configuration, the capacitors C21 and C22 are arranged in this order from the input terminal 2 side. The capacitors C21 and C22 are used to capacitively couple the input terminal 2 and the output terminal 3.

[0024] In terms of the circuit configuration, the first stub-type resonator 21 is provided between the input terminal 2 and the capacitor C21 in the second path 6. In terms of the circuit configuration, the second stub-type resonator 22 is provided between the output terminal 3 and the capacitor C22 in the second path 6. At least one of the first stub-type resonator 21 and the second stub-type resonator 22 has an electrical length equivalent to ¼ of the wavelength corresponding to a predetermined frequency.

[0025] An example of the circuit configuration of the filter device 1 will be described below with reference to Fig. 1. The filter device 1 further includes inductors L1 and L2 and capacitors C1 and C2. One end of the capacitor C1 is connected to the input terminal 2. One end of the capacitor C10 is connected to the other end of the capacitor C1. One end of the capacitor C2 is connected to the other end of the capacitor C10. The other end of the capacitor C2 is connected to the output terminal 3.

[0026] One end of inductor L1 is connected to the connection point between capacitor C1 and capacitor C10. One end of inductor L2 is connected to the connection point between capacitor C2 and capacitor C10. The other ends of inductors L11 and L12 are connected to one end of inductor L1. The other end of inductor L1 is connected to ground.

[0027] One end of the capacitor C11 is connected to one end of the inductor L11. One end of the capacitor C12 is connected to one end of the inductor L12. The other ends of the capacitors C11 and C12 are connected to one end of the inductor L2. The other end of the inductor L2 is connected to ground.

[0028] One end of the first stub-type resonator 21 is connected to the input terminal 2. One end of the capacitor C21 is connected to the other end of the first stub-type resonator 21. One end of the capacitor C22 is connected to the other end of the capacitor C21. One end of the second stub-type resonator 22 is connected to the other end of the capacitor C22. The other end of the second stub-type resonator 22 is connected to the output terminal 3.

[0029] 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.

[0030] The filter device 1 further includes a laminate 50 including a plurality of laminated dielectric layers and a plurality of laminated conductor layers. The input terminal 2, the output terminal 3, the resonant circuit 10, the first stub-type resonator 21, the second stub-type resonator 22, the inductors L1 and L2, and the capacitors C1, C2, C21, and C22 are integrated into the laminate 50.

[0031] 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.

[0032] 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.

[0033] As shown in FIG. 2, the bottom surface 50A is located at the end of the laminate 50 in the -Z direction. The top surface 50B is located at the end of the laminate 50 in the Z direction. The bottom surface 50A and the top surface 50B each have a rectangular shape that is long in the X direction. The side surface 50C is located at the end of the laminate 50 in the -X direction. The side surface 50D is located at the end of the laminate 50 in the X direction. The side surface 50E is located at the end of the laminate 50 in the -Y direction. The side surface 50F is located at the end of the laminate 50 in the Y direction.

[0034] The bottom surface 50A faces a substrate or other object to be mounted (not shown). The bottom surface 50A corresponds to the "first surface" in the present invention. The top surface 50B of the laminate 50 is located on the opposite side to the bottom surface 50A. The top surface 50B corresponds to the "second surface" in the present invention.

[0035] The input terminal 2 and the output terminal 3 are arranged on the bottom surface 50A of the laminate 50. The filter device 1 further includes terminals 111, 112, 113, and 114 arranged on the bottom surface 50A of the laminate 50. The terminals 111, 112, and 113 are arranged in this order in the X direction at positions closer to the side surface 50E than to the side surface 50F. The input terminal 2 is arranged ahead of the terminal 111 in the Y direction. The output terminal 3 is arranged ahead of the terminal 113 in the Y direction. The terminal 114 is arranged ahead of the terminal 112 in the Y direction. Each of the terminals 111 to 114 is connected to ground.

[0036] 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(a) to 6. In this example, the laminate 50 has 11 laminated dielectric layers. Hereinafter, these 11 dielectric layers will be referred to as the first to 11th dielectric layers, in order from the bottom up. The first to 11th dielectric layers will be denoted by reference numerals 51 to 61.

[0037] 3(a) to 6, the circles represent the through holes. The dielectric layers 51 to 59 each have a plurality of through holes formed therein. The through holes are formed by filling holes for the through holes with conductive paste. Each of the through holes is connected to a terminal, a conductive layer, or another through hole.

[0038] Fig. 3(a) shows the pattern-formed surface of the first dielectric layer 51. An input terminal 2, an output terminal 3, and terminals 111 to 114 are formed on the pattern-formed surface of the dielectric layer 51. In Fig. 3(a), two specific through-holes connected to the input terminal 2 and the output terminal 3 are indicated by the reference symbols 51T1 and 51T2, respectively.

[0039] Fig. 3(b) shows the pattern formation surface of the second dielectric layer 52. A capacitor conductor layer 521 and a conductor layer 522 are formed on the pattern formation surface of the dielectric layer 52. In Fig. 3(b), two specific through holes connected to specific through holes 51T1 and 51T2 formed in the dielectric layer 51 are indicated by the reference symbols 52T1 and 52T2, respectively.

[0040] FIG. 3(c) shows the pattern-formed surface of the third dielectric layer 53. Resonator conductor layers 531 and 532 are formed on the pattern-formed surface of the dielectric layer 53. The conductor layers 531 and 532 each have a first end and a second end located opposite each other. The first end of the conductor layer 531 and the first end of the conductor layer 532 are adjacent to each other with a predetermined gap between them. A specific through-hole 52T1 formed in the dielectric layer 52 is connected to a portion of the conductor layer 531 near its second end. A specific through-hole 52T2 formed in the dielectric layer 52 is connected to a portion of the conductor layer 532 near its second end.

[0041] Also, in Figure 3(c), a specific through hole connected to a portion near the second end of the conductor layer 531 is indicated by the symbol 53T1, and a specific through hole connected to a portion near the second end of the conductor layer 532 is indicated by the symbol 53T2.

[0042] 4(a) shows the pattern formation surface of the fourth dielectric layer 54. Inductor conductor layers 541 and 542 are formed on the pattern formation surface of the dielectric layer 54. Each of the conductor layers 541 and 542 has a first end and a second end located opposite to each other.

[0043] 4(a), two specific through holes connected to specific through holes 53T1 and 53T2 formed in the dielectric layer 53 are indicated by reference numerals 54T1 and 54T2, respectively. Also, a specific through hole connected to a portion near the first end of the conductor layer 541 is indicated by reference numeral 54T3, a specific through hole connected to a portion near the second end of the conductor layer 541 is indicated by reference numeral 54T4, a specific through hole connected to a portion near the first end of the conductor layer 542 is indicated by reference numeral 54T5, and a specific through hole connected to a portion near the second end of the conductor layer 542 is indicated by reference numeral 54T6.

[0044] 4(b) shows the pattern-formed surfaces of the fifth and sixth dielectric layers 55, 56. Specific through holes 55T1, 55T2, 55T3, 55T4, 55T5, and 55T6 are formed in each of the dielectric layers 55, 56. Specific through holes 54T1 to 54T6 formed in the dielectric layer 54 are connected to specific through holes 55T1 to 55T6 formed in the dielectric layer 55, respectively. Furthermore, in the dielectric layers 55, 56, adjacent through holes with the same reference numerals are connected to each other.

[0045] 4(c) shows the pattern formation surface of the seventh dielectric layer 57. A capacitor conductor layer 571 and conductor layers 572, 573, and 574 are formed on the pattern formation surface of the dielectric layer 57. A specific through-hole 55T1 formed in the dielectric layer 56 is connected to the conductor layer 572. A specific through-hole 55T2 formed in the dielectric layer 56 is connected to the conductor layer 573. Specific through-holes 55T4 and 55T6 formed in the dielectric layer 56 are connected to the conductor layer 574.

[0046] 4(c), two specific through holes connected to the conductor layers 572 and 573 are denoted by reference numerals 57T1 and 57T2, respectively. Two specific through holes connected to the specific through holes 55T3 and 55T5 formed in the dielectric layer 56 are denoted by reference numerals 57T3 and 57T5, respectively.

[0047] 5(a) shows the pattern-formed surface of the eighth dielectric layer 58. Capacitor conductor layers 581 and 582 and conductor layers 583 and 584 are formed on the pattern-formed surface of the dielectric layer 58. Specific through-holes 57T1, 57T2, 57T3, and 57T5 formed in the dielectric layer 57 are connected to the conductor layers 581, 582, 583, and 584, respectively. Also, in FIG. 5(a), two specific through-holes connected to the conductor layers 583 and 584 are indicated by the reference numerals 58T3 and 58T5, respectively.

[0048] 5(b) shows the pattern-formed surface of the ninth dielectric layer 59. Capacitor conductor layers 591 and 592 are formed on the pattern-formed surface of the dielectric layer 59. Specific through-holes 58T3 and 58T5 formed in the dielectric layer 58 are connected to the conductor layers 591 and 592, respectively.

[0049] 5(c) shows the pattern-formed surface of the tenth dielectric layer 60. On the pattern-formed surface of the dielectric layer 60, a ground conductor layer 601 is formed.

[0050] 6 shows the pattern-formed surface of the eleventh dielectric layer 61. On the pattern-formed surface of the dielectric layer 61, a mark 611 is formed.

[0051] The laminate 50 shown in Figure 2 is constructed by stacking the first to eleventh dielectric layers 51-61 so that the pattern-forming surface of the first dielectric layer 51 becomes the bottom surface 50A of the laminate 50, and the surface opposite the pattern-forming surface of the eleventh dielectric layer 61 becomes the top surface 50B of the laminate 50.

[0052] Each of the multiple through holes shown in Figures 3(a) to 5(b), excluding the multiple specific through holes with reference numerals, is connected to a conductor layer that overlaps it in the stacking direction T when the first to eleventh dielectric layers 51 to 61 are stacked, or to another through hole that overlaps it in the stacking direction T. Furthermore, of the multiple through holes shown in Figures 3(a) to 5(b), excluding the multiple specific through holes, a through hole that is located within a terminal or a conductor layer is connected to that terminal or that conductor layer.

[0053] Fig. 7 shows the inside of a laminate 50 formed by stacking first to eleventh dielectric layers 51 to 61. Fig. 8 shows a part of the inside of the laminate 50 shown in Fig. 7. As shown in Figs. 7 and 8, inside the laminate 50, the multiple conductor layers and multiple through holes shown in Figs. 3(a) to 6 are stacked.

[0054] The following describes the correspondence between the circuit components of the filter device 1 shown in Fig. 1 and the internal components of the laminate 50 shown in Fig. 3(a) to Fig. 9(b). The inductor L11 of the LC resonator 11 is composed of an inductor conductor layer 541 and specific through holes 54T3, 54T4, 55T3, 55T4, and 57T3. The capacitor C11 of the LC resonator 11 is composed of a capacitor conductor layer 591, a ground conductor layer 601, and a dielectric layer 59 between these conductor layers.

[0055] The inductor L12 of the LC resonator 12 is formed by an inductor conductor layer 542 and specific through holes 54T5, 54T6, 55T5, 55T6, and 57T5. The capacitor C12 of the LC resonator 12 is formed by a capacitor conductor layer 592, a ground conductor layer 601, and a dielectric layer 59 between these conductor layers.

[0056] The capacitor C21 is composed of a capacitor conductor layer 521, a resonator conductor layer 531, and a dielectric layer 52 between these conductor layers. The capacitor C22 is composed of a capacitor conductor layer 521, a resonator conductor layer 532, and a dielectric layer 52 between these conductor layers.

[0057] The first stub-type resonator 21 is formed by a resonator conductor layer 531. The second stub-type resonator 22 is formed by a resonator conductor layer 532. In this example, both the first stub-type resonator 21 and the second stub-type resonator 22 have an electrical length equivalent to ¼ of the wavelength corresponding to a predetermined frequency.

[0058] Capacitor C1 is composed of capacitor conductor layers 581 and 591 and a dielectric layer 58 between these conductor layers. Capacitor C2 is composed of capacitor conductor layers 582 and 592 and a dielectric layer 58 between these conductor layers. Capacitor C10 is composed of capacitor conductor layers 571, 591, and 592 and a dielectric layer 57 between these conductor layers.

[0059] A part of the inductor L1 is formed by a plurality of through holes that connect the conductor layer 574 and the ground conductor layer 601. Another part of the inductor L2 and the inductor L2 are formed by a plurality of through holes that connect the terminals 111 to 114 and the ground conductor layer 601.

[0060] Next, structural features of the filter device 1 according to this embodiment will be described with reference to Fig. 2 to Fig. 9. Fig. 9 is a plan view showing a part of the interior of the laminate 50 shown in Fig. 7. The resonance circuit 10, capacitors C21 and C22, the first stub-type resonator 21, and the second stub-type resonator 22 are arranged in the laminate 50.

[0061] The ground conductor layer 601 is integrated with the laminate 50 and connected to the ground. In particular, in this embodiment, the ground conductor layer 601 is disposed within the laminate 50. The resonance circuit 10, the capacitors C21 and C22, the first stub-type resonator 21, and the second stub-type resonator 22 are present between the bottom surface 50A and the ground conductor layer 601 in the lamination direction T, but are not present between the top surface 50B and the ground conductor layer 601.

[0062] At least some of the elements constituting the resonant circuit 10 are arranged between the first and second stub-type resonators 21, 22 and the ground conductor layer 601 in the stacking direction T. In this embodiment, the inductors L11, L12, the capacitor C11 (excluding the ground conductor layer 601), and the capacitor C12 (excluding the ground conductor layer 601) are arranged between the resonator conductor layers 531, 532 and the ground conductor layer 601 in the stacking direction T.

[0063] The resonator conductor layer 531, i.e., the first stub-type resonator 21, includes two portions extending in different directions. Similarly, the resonator conductor layer 532, i.e., the second stub-type resonator 22, includes two portions extending in different directions. In this embodiment, each of the first and second stub-type resonators 21, 22 (resonator conductor layers 531, 532) includes a portion extending in a direction parallel to the X direction and a portion extending in a direction parallel to the Y direction. The physical length of the first stub-type resonator 21 (the physical length of the resonator conductor layer 531) and the physical length of the second stub-type resonator 22 (the physical length of the resonator conductor layer 532) are equal to each other.

[0064] 9, a virtual plane that passes between the first stub-type resonator 21 and the second stub-type resonator 22 and is parallel to the stacking direction T is represented by the symbol P. The virtual plane P is a plane that is parallel to the YZ plane and perpendicular to each of the bottom surface 50A and the top surface 50B. The virtual plane P intersects with the laminate 50 at the center of the laminate 50 in the longitudinal direction (direction parallel to the X direction) of the bottom surface 50A or the top surface 50B. The shape and arrangement of the first stub-type resonator 21 (the resonator conductor layer 531) and the shape and arrangement of the second stub-type resonator 22 (the resonator conductor layer 532) are symmetrical with respect to the virtual plane P.

[0065] In addition, in the laminate 50, the multiple conductors (multiple conductor layers and multiple through holes) constituting a portion including the input terminal 2, the terminal 111, the LC resonator 11 (inductors L11, C11), the first stub-type resonator 21, and the capacitor C1 are referred to as multiple first conductors. In addition, in the laminate 50, the multiple conductors (multiple conductor layers and multiple through holes) constituting a portion including the output terminal 3, the terminal 113, the LC resonator 12 (inductors L12, C12), the second stub-type resonator 22, and the capacitor C2 are referred to as multiple second conductors. The shape and arrangement of the multiple first conductors are symmetrical to the shape and arrangement of the multiple second conductors with respect to an imaginary plane P.

[0066] The resonator conductor layers 531 and 532 are arranged at the same position in the stacking direction T. Therefore, the first stub-type resonator 21 and the second stub-type resonator 22 are arranged at the same position in the stacking direction T. The first stub-type resonator 21 (resonator conductor layer 531) is connected to the input terminal 2 via specific through holes 51T1 and 52T1. The second stub-type resonator 22 (resonator conductor layer 532) is connected to the input terminal 2 via specific through holes 51T2 and 52T2. Output terminal 3 is connected to.

[0067] The capacitors C21 and C22 include a capacitor conductor layer 521. The capacitor conductor layer 521 is disposed at a position different from the resonator conductor layers 531 and 532, i.e., the first and second stub-type resonators 21 and 22, in the stacking direction T. The capacitor conductor layer 521 faces a first end of the resonator conductor layer 531, i.e., a portion near one end of the first stub-type resonator 21, and a first end of the resonator conductor layer 532, i.e., a portion near one end of the second stub-type resonator 22.

[0068] Here, a structure formed by connecting two or more through holes in series is referred to as a through-hole row. The laminate 50 includes through-hole rows T3, T4, T5, and T6. The through-hole row T3 is formed by specific through-holes 54T3, 55T3, and 57T3. The through-hole row T4 is formed by specific through-holes 54T4 and 55T4. The through-hole row T5 is formed by specific through-holes 54T5, 55T5, and 57T5. The through-hole row T6 is formed by specific through-holes 54T6 and 55T6.

[0069] The inductor L11 of the LC resonator 11 includes through-hole rows T3 and T4 and an inductor conductive layer 541. The inductor conductive layer 541 connects the through-hole rows T3 and T4. The inductor conductive layer 541 is disposed between the bottom surface 50A and the through-hole rows T3 and T4 in the stacking direction T.

[0070] The inductor L12 of the LC resonator 12 includes through-hole rows T5 and T6 and an inductor conductive layer 542. The inductor conductive layer 542 connects the through-hole rows T5 and T6. The inductor conductive layer 542 is disposed between the bottom surface 50A and the through-hole rows T5 and T6 in the stacking direction T.

[0071] Each of the inductor conductive layers 541 and 542 includes portions extending in different directions. In particular, in this embodiment, each of the inductor conductive layers 541 and 542 includes one portion extending in a direction parallel to the X direction and two portions extending in a direction parallel to the Y direction.

[0072] Next, the operation and effect of the filter device 1 according to this embodiment will be described. In this embodiment, a resonant circuit 10 is provided in the first path 5, and capacitors C21 and C22 are provided in the second path 6. In this embodiment, based on the configuration of the resonant circuit 10 and the capacitors C21 and C22, part of the second path 6 is configured as the first and second stub-type resonators 21 and 22. Specifically, in this embodiment, on the pattern-forming surface of the third dielectric layer 53, a conductor layer extending from a specific through-hole 52T1 to a position facing the capacitor conductor layer 521 is configured as the resonator conductor layer 531. Similarly, on the pattern-forming surface of the dielectric layer 53, a conductor layer extending from a specific through-hole 52T2 to a position facing the capacitor conductor layer 521 is configured as the resonator conductor layer 532. As a result, according to this embodiment, the first and second stub-type resonators 21 and 22 can be added without increasing the dimensions of the filter device 1.

[0073] Here, the significance of adding the first and second stub-type resonators 21, 22 will be explained. In a multilayer bandpass filter using a laminate 50, such as the filter device 1 according to this embodiment, antiresonance may occur at the high-frequency side of the pass band, depending on the structure of the laminate 50, resulting in a small pass attenuation. In particular, when a ground conductor layer covering the resonant circuit is provided as in this embodiment, antiresonance is likely to occur at the high-frequency side of the pass band due to coupling between the conductor layer constituting the resonant circuit and the ground conductor layer. The above problem is not limited to cases where the ground conductor layer is provided inside the laminate, but also applies to cases where the ground conductor layer is provided on the top surface of the laminate.

[0074] In contrast, in this embodiment, the first and second stub-type resonators 21 and 22 are provided to form attenuation poles near the frequencies at which antiresonance occurs, thereby increasing the amount of pass attenuation at the higher frequencies of the passband. Each of the first and second stub-type resonators 21 and 22 has an electrical length equivalent to ¼ of the wavelength corresponding to a predetermined frequency. The predetermined frequency may be the same as the frequency at which antiresonance occurs, or may be a frequency different from the frequency at which antiresonance occurs.

[0075] Furthermore, the first and second stub-type resonators 21, 22 may have the same electrical length or may have different frequencies. When the first and second stub-type resonators 21, 22 have the same electrical length, the first and second stub-type resonators 21, 22 essentially form one attenuation pole. In this case, the attenuation at the attenuation pole can be increased. When the first and second stub-type resonators 21, 22 have different electrical lengths, two attenuation poles can be formed. In this case, the attenuation at the attenuation pole can be increased over a relatively wide frequency band.

[0076] The effects of this embodiment will be described below with reference to simulation results. In the simulation, a model of an example, a model of a modified example, and a model of a comparative example were used. The model of the example is a model of the filter device 1 according to this embodiment. The model of the modified example is a model of a filter device of a modified example. The model of the comparative example is a model of a filter device of a comparative example.

[0077] First, the configuration of a modified filter device 101 will be described. FIG. 10 is a plan view showing a part of the interior of the laminate 50 in the modified filter device 101. The modified filter device 101 is a modification of the filter device 1 according to the present embodiment. The filter device 101 includes a capacitor conductor layer 1521 and resonator conductor layers 1531 and 1532 instead of the capacitor conductor layer 521 and resonator conductor layers 531 and 532 in the present embodiment. The capacitor conductor layer 1521 is formed on the second dielectric layer 52. The resonator conductor layers 1531 and 1532 are formed on the third dielectric layer 53. The other configurations of the filter device 101 are the same as those of the filter device 1 according to the present embodiment.

[0078] Each of the conductor layers 1531 and 1532 has a first end and a second end located opposite to each other. The first end of the conductor layer 1531 and the first end of the conductor layer 1532 are adjacent to each other with a predetermined gap between them. A specific through-hole 52T1 (see FIG. 3(b)) and a specific through-hole 53T1 formed in the dielectric layer 52 are connected to a portion of the conductor layer 1531 near its second end. A specific through-hole 52T2 (see FIG. 3(b)) and a specific through-hole 53T2 formed in the dielectric layer 52 are connected to a portion of the conductor layer 1532 near its second end.

[0079] The circuit configuration of the filter device 101 is the same as that of the filter device 1 shown in Fig. 1. In the filter device 101, the capacitor C21 is composed of a capacitor conductor layer 1521, a resonator conductor layer 1531, and a dielectric layer 52 between these conductor layers. The capacitor C22 is composed of a capacitor conductor layer 1521, a resonator conductor layer 1532, and a dielectric layer 52 between these conductor layers. The first stub-type resonator 21 is composed of the conductor layer 1531. The second stub-type resonator 22 is composed of the conductor layer 1532.

[0080] In the filter device 101, the physical length of the first stub-type resonator 21 (the resonator conductor layer 1531) and the physical length of the second stub-type resonator 22 (the resonator conductor layer 1 The physical lengths of the first and second stub-type resonators 21, 22 (resonator conductor layers 1531, 1532) are different from each other. That is, each of the first and second stub-type resonators 21, 22 (resonator conductor layers 1531, 1532) includes a first portion extending in a direction parallel to the X direction and a second portion extending in a direction parallel to the Y direction. The first portion of the first stub-type resonator 21 (resonator conductor layer 1531) is shorter than the first portion of the second stub-type resonator 22 (resonator conductor layer 1532), and the lengths of the second portions of the first stub-type resonator 21 (resonator conductor layer 1531) and the second stub-type resonator 22 (resonator conductor layer 1532) are equal to each other. Therefore, the overall physical length of the first stub-type resonator 21 (resonator conductor layer 1531) is shorter than the overall physical length of the second stub-type resonator 22 (resonator conductor layer 1532).

[0081] The physical length of the first stub-type resonator 21 in the modified example (the physical length of the resonator conductor layer 531) is shorter than the physical length of the first stub-type resonator 21 in the present embodiment (the physical length of the resonator conductor layer 531). The physical length of the second stub-type resonator 22 in the modified example (the physical length of the resonator conductor layer 532) is longer than the physical length of the second stub-type resonator 22 in the present embodiment (the physical length of the resonator conductor layer 532).

[0082] The capacitor conductor layer 1521 faces a first end of the resonator conductor layer 1531, i.e., a portion near one end of the first stub-type resonator 21, and a first end of the resonator conductor layer 1532, i.e., a portion near one end of the second stub-type resonator 22.

[0083] Next, the configuration of a filter device 201 of the comparative example will be described. Fig. 11 is a plan view showing a part of the inside of the laminate 50 in the filter device 201 of the comparative example. The filter device 201 does not have the first and second stub-type resonators 21 and 22 of the present embodiment. Furthermore, the filter device 201 has a capacitor conductor layer 2521 and conductor layers 2531 and 2532 instead of the capacitor conductor layer 521 and resonator conductor layers 531 and 532 of the present embodiment. The conductor layer 1521 is formed on the second dielectric layer 52. The conductor layers 2531 and 2532 are formed on the third dielectric layer 53. The other configurations of the filter device 201 are the same as those of the filter device 1 of the present embodiment.

[0084] Each of the conductor layers 2531 and 2532 has a first end and a second end located opposite to each other. The first end of the conductor layer 2531 and the first end of the conductor layer 2532 are aligned at a predetermined interval in a direction parallel to the X direction. A specific through-hole 52T1 (see FIG. 3(b)) and a specific through-hole 53T1 formed in the dielectric layer 52 are connected to a portion of the conductor layer 2531 near its second end. A specific through-hole 52T2 (see FIG. 3(b)) and a specific through-hole 53T2 formed in the dielectric layer 52 are connected to a portion of the conductor layer 2532 near its second end.

[0085] The circuit configuration of the filter device 201 is the same as that of the filter device 1 shown in Fig. 1, except that the first and second stub-type resonators 21 and 22 are not provided. In the filter device 201, the capacitor C21 is composed of a capacitor conductor layer 2521, a conductor layer 2531, and a dielectric layer 52 between these conductor layers. The capacitor C22 is composed of a capacitor conductor layer 2521, a conductor layer 2532, and a dielectric layer 52 between these conductor layers.

[0086] In the filter device 201, each of the conductor layers 2531 and 2532 includes a first portion extending in a direction parallel to the X direction and a second portion extending in a direction parallel to the Y direction. The physical length of the conductor layer 2531 is shorter than the physical length of the first stub-type resonator 21 in the present embodiment (the physical length of the resonator conductor layer 531). The physical length of the conductor layer 2532 is shorter than the physical length of the second stub-type resonator 22 in the present embodiment (the physical length of the resonator conductor layer 532). Furthermore, the physical length of each of the conductor layers 2531 and 2532 is shorter than the physical length of the first stub-type resonator 21 in the modified example (the physical length of the resonator conductor layer 1531).

[0087] The conductor layer 2521 for the capacitor faces a portion near the first end of the conductor layer 2531 and a portion near the first end of the conductor layer 2532. The conductor layer 2521 for the capacitor is longer than the conductor layer 521 for the capacitor in this embodiment.

[0088] Next, the results of the simulation will be described. In the simulation, the model of the embodiment, the model of the modified example, and the model of the comparative example were designed so that the passband and the amount of transmission attenuation in the passband were approximately the same.

[0089] Fig. 12 is a characteristic diagram showing the pass attenuation characteristics obtained by simulation. In Fig. 12, the horizontal axis represents frequency and the vertical axis represents attenuation. In Fig. 12, the curve labeled 91 represents the pass attenuation characteristics of the model of the embodiment, and the curve labeled 92 represents the pass attenuation characteristics of the model of the embodiment. Variations The curve labeled 93 shows the attenuation characteristics of the comparative model.

[0090] 12, it can be seen that in the comparative example model (reference numeral 93), antiresonance occurs on the high-frequency side of the pass band, and the absolute value of the attenuation in the frequency band on the high-frequency side of the pass band is small. On the other hand, in the example model (reference numeral 91) and the modified example model (reference numeral 92), it can be seen that the absolute value of the attenuation in the frequency band on the high-frequency side of the pass band is larger than that of the comparative example model (reference numeral 93), except for the vicinity of the frequency where antiresonance occurs. As can be seen from this result, according to this embodiment, the first and second stub-type resonators 21 and 22 can increase the pass attenuation (absolute value of the attenuation) in the frequency band on the high-frequency side of the pass band.

[0091] 12, one attenuation pole is formed in the model of the embodiment (reference numeral 91), and two attenuation poles are formed in the model of the modified example (reference numeral 92). Thus, according to the present embodiment, by changing the physical lengths of the first and second stub-type resonators 21 and 22, it is possible to control the pass attenuation characteristics in the frequency band on the higher side of the pass band.

[0092] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the resonance circuit 10 may include only one resonator, or may include three or more resonators.

[0093] The filter device of the present invention may also include a shielding conductor layer disposed on the upper surface 50B of the laminate 50, instead of the ground conductor layer 601. Note that the ground conductor layer 601 is not an essential component of the filter device of the present invention and may not be provided. [Explanation of symbols]

[0094] 1...filter device, 2...input terminal, 3...output terminal, 10...resonant circuit, 11, 12...LC resonator, 21...first stub-type resonator, 22...second stub-type resonator, 50...laminated body, 50A...bottom surface, 50B...top surface, 50C to 50F...side surfaces, 601...ground conductor layer, C1, C2, C10, C11, C12, C21, C22...capacitors, L1, L2, L11, L12...inductors.

Claims

1. a laminate including a plurality of laminated dielectric layers, the laminate having a first surface facing the object to be mounted and a second surface opposite to the first surface; an input terminal and an output terminal disposed on the first surface; a multilayer filter device including a resonant circuit, a capacitor, a first stub-type resonator, and a second stub-type resonator arranged within the multilayer device, the resonant circuit is provided in a first path connecting the input terminal and the output terminal in terms of a circuit configuration; the capacitor is provided in a second path that connects the input terminal and the output terminal and does not pass through the resonant circuit in terms of the circuit configuration; the first stub-type resonator is provided between the input terminal and the capacitor in the second path in terms of a circuit configuration; the second stub-type resonator is provided between the output terminal and the capacitor in the second path in terms of a circuit configuration, the first stub-type resonator and the second stub-type resonator are configured to form an attenuation pole in the pass attenuation characteristics of the multilayer filter device near an anti-resonance frequency that occurs outside the pass band due to the structure of the laminate.

2. further comprising a ground conductor layer integrated with the laminate and connected to ground, 2. The multilayer filter device according to claim 1, wherein the resonant circuit, the capacitor, the first stub-type resonator, and the second stub-type resonator are present between the first surface and the ground conductor layer in a stacking direction of the plurality of dielectric layers, but are not present between the second surface and the ground conductor layer.

3. 3. The multilayer filter device according to claim 2, wherein at least some of the elements constituting the resonant circuit are disposed between the first and second stub-type resonators and the ground conductor layer in the stacking direction of the plurality of dielectric layers.

4. 4. The multilayer filter device according to claim 1, wherein at least one of the first stub-type resonator and the second stub-type resonator has an electrical length equivalent to ¼ of a wavelength corresponding to a predetermined frequency.

5. A laminated filter device as described in claim 4, characterized in that the specified frequency is the same frequency as the frequency at which the anti-resonance occurs or a frequency close to the frequency at which the anti-resonance occurs.

6. 6. The multilayer filter device according to claim 1, wherein the physical length of the first stub-type resonator and the physical length of the second stub-type resonator are equal to each other.

7. 7. The multilayer filter device according to claim 1, wherein the shape and arrangement of the first stub resonator and the shape and arrangement of the second stub resonator are symmetrical with respect to a virtual plane that passes between the first stub resonator and the second stub resonator and is parallel to the lamination direction of the plurality of dielectric layers.

8. 8. The multilayer filter device according to claim 1, wherein the first stub-type resonator and the second stub-type resonator are arranged at the same position in the stacking direction of the plurality of dielectric layers.

9. the capacitor includes a capacitor conductor layer; 9. The multilayer filter device according to claim 1, wherein the conductor layer for the capacitor is disposed at a position different from that of the first and second stub-type resonators in the stacking direction of the plurality of dielectric layers.

10. 10. The multilayer filter device according to claim 9, wherein the capacitor conductor layer faces a portion near one end of the first stub resonator and a portion near one end of the second stub resonator.

Images