Filter circuit

Abstract

To provide a more compact filter circuit.SOLUTION: A filter circuit includes an LC circuit having a first end connected to a signal path connecting an input terminal and an output terminal and a second end connected to a reference potential. The filter circuit according to the first embodiment includes a substrate, and a plurality of electrodes provided on a principal surface or inside of the substrate. The LC circuit includes a first capacitor, a first inductor connected to the first capacitor in parallel, and a second capacitor connected to the first capacitor in serial. When viewed in the thickness direction, the electrodes overlap with one another at least partially. Portions where the electrodes overlap with one another are electrodes of the first capacitor or the second capacitor.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a filter circuit.

Background Art

[0002] Patent Document 1 describes a resonance circuit that attenuates a specific frequency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the resonance device described in Patent Document 1, it is necessary to increase the electrodes in order to secure the capacitance of the capacitor.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a smaller filter circuit.

Means for Solving the Problems

[0006] A filter circuit according to one aspect of the present disclosure is a filter circuit having an LC circuit with one end connected to a signal path connecting an input terminal and an output terminal and the other end connected to a reference potential, the filter circuit comprising: a substrate; a first electrode provided on one main surface of the substrate; a second electrode provided inside the substrate; and a third electrode provided on the other main surface of the substrate, wherein the LC circuit includes: a first capacitor having one electrode connected to the signal path; a first inductor having one electrode connected to the signal path; and a second capacitor having one electrode connected to the first capacitor and the first inductor and the other electrode connected to the reference potential, wherein the first electrode and the second electrode overlap at least partially when viewed in the thickness direction of the substrate, the second electrode and the third electrode overlap at least partially when viewed in the thickness direction of the substrate, a portion of the first electrode that overlaps the second electrode is one electrode of the first capacitor, a portion of the second electrode that overlaps the first electrode is the other electrode of the first capacitor, a portion of the second electrode that overlaps the third electrode is one electrode of the second capacitor, and a portion of the third electrode that overlaps the second electrode is the other electrode of the second capacitor.

Advantages of the Invention

[0007] According to the present disclosure, a smaller filter circuit can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

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Figure 15

Figure 16

[0009] Embodiments of the present invention will be described below. Note that the present invention is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible.

[0010] (First Embodiment) FIG. 1 is a schematic diagram showing a module to which a filter circuit according to the first embodiment is applied. FIG. 2 is a cross-sectional view taken along line II-II according to the first embodiment. A module 1 according to the first embodiment is an integrated module in which a plurality of integrated circuits and various functional components mounted on a substrate 10 are integrated.

[0011] An element 2 is provided on the main surface of the substrate 10 in the module 1. The element 2 is, for example, a surface mount device (SMD). Further, a filter circuit F1 according to the first embodiment is applied to the module 1 and is connected to the element 2. The connection between the filter circuit F1 and the element 2 will be described later.

[0012] FIG. 3 is a circuit diagram showing the filter circuit according to the first embodiment. As shown in FIG. 3, a filter circuit F1 according to the first embodiment is a notch filter in which an LC circuit having one end connected to a signal path connecting an input terminal IN and an output terminal OUT and the other end connected to a ground GND is connected. The LC circuit includes a first capacitor C1, a first inductor L1, and a second capacitor C2. One electrode of the first capacitor C1 is connected to a node N1 on the signal path, and the other electrode of the first capacitor C1 is connected to one electrode of the second capacitor C2. One end of the first inductor L1 is connected to a node N2 on the signal path, and the other end of the first inductor L1 is connected to one electrode of the second capacitor C2. That is, the first inductor L1 is connected in parallel with the first capacitor. One electrode of the second capacitor C2 is connected to the other electrode of the first capacitor C1 and the other end of the first inductor L1, and the other electrode of the second capacitor C2 is connected to the ground GND. That is, the second capacitor C2 is connected in series with the first capacitor C1 and the first inductor L1. Thereby, by appropriately adjusting the sum of the capacitances of the first capacitor C1 and the second capacitor C2 and the inductance of the first inductor L1, a signal can be attenuated at a desired attenuation pole by a parallel resonance circuit.

[0013] Here, the capacitance of the first capacitor C1 is 0.03 pF or more. Thus, since the capacitance of the first capacitor C1 contributes to the resonance characteristics, a signal can be attenuated at a desired attenuation pole.

[0014] Here, it is preferable that the capacitances of the first capacitor C1 and the second capacitor C2 are the same. In the filter circuit F1 according to FIG. 3, the larger the sum of the capacitances of the first capacitor C1 and the second capacitor C2, the smaller the frequency of the attenuation pole can be made. On the other hand, even if the capacitances of the first capacitor C1 and the second capacitor are made different, if the sum of the capacitances is the same, the frequency of the attenuation pole does not change. Therefore, by making the capacitances of the first capacitor C1 and the second capacitor C2 the same, the frequency of the attenuation pole can be reduced while suppressing an increase in the electrode area of the first capacitor C1 or the second capacitor C2.

[0015] As shown in FIG. 2, the filter circuit F1 according to the first embodiment includes a substrate 10, a protective film 11, a first pattern 20, a second pattern 30, and a third electrode 40.

[0016] The substrate 10 is exemplified by a ceramic laminated substrate such as a low-temperature co-fired ceramics (LTCC) substrate, a resin multilayer substrate, a film substrate, or the like. The base material of the substrate 10 is a dielectric. The substrate 10 has a main surface 10a. In the following description, the thickness direction of the substrate 10 is defined as the Z direction, the direction perpendicular to the Z direction is defined as the X direction, and the direction perpendicular to the Z direction and the X direction is defined as the Y direction.

[0017] FIG. 4 is a schematic diagram showing the main surface of the substrate of the filter circuit according to the first embodiment. The first pattern 20 is a conductor pattern provided on the main surface 10a of the substrate 10. The first pattern 20 according to the first embodiment has a main line 21, a first electrode 22, a fourth electrode 23, and a conduction via 24.

[0018] The main line 21 is the signal path of the filter circuit F1. That is, the main line 21 is at least a part of the line connecting the input terminal and the output terminal of the filter circuit F1. In the example of FIG. 4, the main line 21 extends in the X direction, the main line 21 is connected to an output terminal (not shown) on one side in the X direction, and is connected to a first electrode 22 corresponding to the input terminal on the other side in the X direction.

[0019] The first electrode 22 corresponds to one electrode of the first capacitor C1. That is, the first electrode 22 is connected to the main line 21. Here, the first electrode 22 is an electrode whose minimum length in the Z direction in plan view is larger than the width of the main line 21. The width of the main line 21 refers to the average of the lengths in the direction perpendicular to the extending direction of the main line 21. In the example of FIG. 4, the width of the main line 21 refers to the Y direction. Also, the minimum length of the first electrode 22 refers to the minimum distance between two different points on the edge of the first electrode 22. In the example of FIG. 4, the minimum length of the first electrode 22 refers to the length in the X direction. In the example of FIG. 4, the first electrode 22 is connected to the main line 21 on one side in the X direction, but this is merely an example, and it is sufficient if it is connected to the main line 21. Also, the shape of the first electrode is rectangular, but it is not limited to this, and other shapes such as circular may be used.

[0020] The fourth electrode 23 is a connection terminal to the element 2. The fourth electrode 23 is provided separately from the first electrode 22. In the example of FIG. 4, three fourth electrodes 23 are provided separately from the first electrode 22 in the X direction, and both ends of the element 2 in the X and Y directions are arranged so as to overlap the first electrode 22 or the fourth electrode 23.

[0021] The via 24 is a via connecting the main line 21 and a transmission line 31 described later. The via 24 connects the main line 21 to one end of the transmission line 31 in the Z direction. In the example of FIG. 4, the via 24 is provided on the main line 21, but this is merely an example.

[0022] FIG. 5 is a schematic diagram showing the inside of the substrate of the filter circuit according to the first embodiment. The second pattern 30 is a conductor pattern provided inside the substrate 10. The second pattern 30 according to the first embodiment has a transmission line 31 and a second electrode 32.

[0023] The transmission line 31 is a transmission line that connects the main line 21 and the second electrode 32. Here, the transmission line refers to a layer of conductor having a shape linearly extending in a Z-direction in a plan view. In the example of FIG. 4, one end of the transmission line 31 is connected to the conductive via 24, and the other end is connected to the second electrode 32.

[0024] In the first embodiment, the transmission line 31 corresponds to the first inductor L1. In the example of FIG. 5, the transmission line 31 is in a meander shape. Here, the meander shape means a shape that extends in one direction and alternately extends in one direction and the other direction in a direction intersecting the one direction, and meanders. In the example of FIG. 5, the transmission line 31 extends in the X-direction and alternately extends in one direction and the other direction in the Y-direction, and meanders. Thereby, sufficient inductance can be generated by the transmission line 31.

[0025] The second electrode 32 corresponds to the other electrode of the first capacitor C1 and one electrode of the second capacitor C2. Here, the second electrode 32 is an electrode whose minimum length in a plan view in the Z-direction is larger than the width of the main line 21. The minimum length of the second electrode 32 refers to the minimum distance between two different points on the edge of the second electrode 32. In the example of FIG. 5, the minimum length of the second electrode 32 refers to the length in the X-direction. The second electrode 32 overlaps the first electrode 22 and the third electrode 40 when viewed in the Z-direction. Since the base material of the substrate 10 is a dielectric, the second electrode 32 can generate capacitance as the first capacitor C1 between the second electrode 32 and the first electrode 22. Also, the second electrode 32 can generate capacitance as the second capacitor C2 between the second electrode 32 and the third electrode 40. Note that the shape of the second electrode 32 is rectangular, but is not limited thereto, and may be other shapes such as circular.

[0026] In the first embodiment, the minimum distance in the width direction between the edge in the width direction of the transmission line 31 and the edge of the second electrode 32 is 20 μm or more. Here, the width direction of the transmission line 31 refers to the direction perpendicular to the extending direction of the transmission line 31, and the edge in the width direction of the transmission line 31 refers to the edge extending in the extending direction of the transmission line 31 that is in the width direction of the transmission line 31. Thereby, since the transmission line 31 and the second electrode 32 are sufficiently separated, it is possible to suppress the generation of parasitic components between the transmission line 31 and the second electrode 32.

[0027] The third electrode 40 corresponds to the other electrode of the second capacitor C2. That is, the third electrode 40 is connected to the ground GND. Here, the third electrode 40 is an electrode whose minimum length in a plan view in the Z direction is larger than the width of the main line 21. The minimum length of the third electrode 40 refers to the minimum distance between two different points on the edge of the third electrode 40. The third electrode 40 is provided on the other main surface of the substrate 10, that is, the main surface opposite to the main surface 10a. Further, the third electrode 40 is a conductor film provided so as to cover the other main surface of the substrate 10, but this is merely an example, and it may be a conductor film provided on a part of the main surface opposite to the main surface 10a.

[0028] Hereinafter, in the module 1 according to the first embodiment, the connection between the filter circuit F1 and the element 2 and the protective film 11 will be described in detail.

[0029] As shown in FIG. 2, the element 2 is connected to the first electrode 22 via a conductive bonding material 3 such as a solder paste containing a low melting point metal. The element 2 is connected to the fourth electrode 23 via the conductive bonding material 3. The low melting point metal is called solder and is, for example, a tin alloy.

[0030] In FIGS. 1 and 4, the region where the protective film 11 is provided is shown as a hatched region. The protective film 11 is a film made of an insulator provided on the main surface 10a. The material of the protective film 11 is, for example, a dielectric used as a resist. In the example of FIG. 4, the protective film 11 has a protective film 11a provided so as to surround the element 2 and a protective film 11b provided so as to overlap the first electrode 22.

[0031] In the region 22b of the first electrode 22, the protective film 11b is not provided. That is, in the example of FIG. 4, the first electrode 22 has a region 22b where at least a part of the surface of the first electrode 22 is exposed because the protective film 11 is not provided. The conductive bonding material 3 is disposed in the region 22b, and the element is connected to the first electrode 22 via the conductive bonding material 3 in the region 22b. Thereby, since the first electrode 22 is also used as a connection terminal to the element 2, the filter circuit F1 becomes smaller.

[0032] In the first embodiment, the protective film 11b is provided so as to surround the region 22b. Thereby, the region 22b becomes the bottom of the concave protective film 11b. Thereby, when the element 2 is mounted, it is possible to suppress the outflow of the conductive bonding material 3 from the region 22a, and the mounting of the element 2 becomes easy.

[0033] As described above, the filter circuit F1 according to the first embodiment has been described. However, the filter according to the first embodiment is not limited to those shown in FIGS. 1 to 5. The substrate 10 according to the first embodiment discloses a portion where the filter circuit F1 is located, but there may be circuits other than the filter circuit F1. Hereinafter, modification examples will be described with reference to the drawings, but descriptions of the same configurations as those described above will be omitted.

[0034] (First Modification Example) FIG. 6 is a schematic diagram showing a main surface of a substrate of a filter circuit according to the first modification example. FIG. 7 is a schematic diagram showing the inside of a substrate of a filter circuit according to the first modification example. As shown in FIG. 6, the filter circuit according to the first modification example may further include an element 12 which is a surface mount element as an inductor. The element 12 is provided on the main surface 10a of the substrate 10. In FIG. 6, the protective film is the same as the protective film 11 shown in FIG. 4 except that the protective film is not provided in the region of the electrode 25 that is connected to the element 12.

[0035] As shown in FIG. 6, the first pattern 20A according to the first modification further includes an electrode 25. In the example of FIG. 6, one of the electrodes 25 is provided on the main line 21, and the other of the electrodes 25 is connected to the conduction via 24. Thereby, both ends of the element 12 can be connected to a set of electrodes 25 provided in the first pattern 20A. As shown in FIG. 7, the transmission line 31A according to the first modification is linear and connects the second electrode 32 and the conduction via 24.

[0036] (Second Modification) FIG. 8 is a schematic diagram showing the inside of the substrate of the filter circuit according to the second modification. As shown in FIG. 8, in the filter circuit according to the second modification, the second electrode 32B partially overlaps the first electrode 22 in a plan view in the Z direction. The first pattern 20 and the protective film according to the second modification are the same as the protective film 11 shown in FIG. 4. In this case, in the first electrode 22, the region overlapping the second electrode 32B in a plan view in the Z direction corresponds to one electrode of the first capacitor C1. Further, a capacitor can be formed with the first electrode 22 as one electrode and the third electrode 40 as the other electrode.

[0037] (Third Modification) FIG. 9 is a schematic diagram showing the main surface of the substrate of the filter circuit according to the third modification. FIG. 10 is a schematic diagram showing the inside of the substrate of the filter circuit according to the third modification. As shown in FIGS. 9 and 10, in the filter circuit according to the third modification, a part of the main line 21 and the conduction via 24 are provided on the element 2 side in the X direction with respect to the first electrode 22, and the second pattern 30B is inverted in the X direction centering on the second electrode 32. Thereby, in the third modification, the transmission line 31 overlaps the fourth electrode 23 of the first pattern 20. In the example of FIG. 9, the main line 21C includes a main line 21a provided on the side opposite to the element 2 side in the X direction with respect to the first electrode 22 and a main line 21b provided on the element 2 side in the X direction with respect to the first electrode 22. Here, the main line 21b is connected to an output terminal (not shown). The protective film according to the third modification is the same as the protective film 11 shown in FIG. 4.

[0038] As shown in FIG. 10, in the third modification example, the width of the portion of the transmission line 31 that overlaps with the fourth electrode 23 is smaller than the minimum length of the fourth electrode 23. Here, the width of the portion of the transmission line 31 that overlaps with the fourth electrode 23 refers to the average of the lengths in the direction perpendicular to the extending direction of the portion of the transmission line 31 that overlaps with the fourth electrode 23 when viewed in a plan view in the Z direction. Also, the minimum length of the fourth electrode 23 refers to the minimum distance between two different points on the edge of the fourth electrode 23. Thereby, it is possible to suppress the generation of parasitic capacitance between the transmission line 31 and the fourth electrode 23.

[0039] Note that the filter circuit according to the first embodiment is not limited to the modification examples described above.

[0040] For example, the third electrode is not limited to being provided on the main surface opposite to the main surface 10a, and may be provided inside the substrate 10 on the side opposite to the first electrode 22 with respect to the second electrode 32.

[0041] For example, the first electrode may overlap only a part of the second electrode. In this case, in the first electrode, the region that overlaps with the second electrode when viewed in a plan view in the Z direction corresponds to one electrode of the first capacitor.

[0042] For example, the second electrode may overlap only a part of the third electrode. In this case, in the second electrode, the region that overlaps with the third electrode when viewed in a plan view in the Z direction corresponds to one electrode of the second capacitor.

[0043] For example, the third electrode may overlap only a part of the second electrode. In this case, in the third electrode, the region that overlaps with the second electrode when viewed in a plan view in the Z direction corresponds to the other electrode of the second capacitor.

[0044] As described above, the filter circuit F1 according to the first embodiment is a filter circuit F1 having an LC circuit with one end connected to a signal path (main line 21) connecting an input terminal IN and an output terminal OUT and the other end connected to a reference potential (ground GND). The filter circuit F1 according to the first embodiment includes a substrate 10, a first electrode 22 provided on one main surface 10a of the substrate 10, a second electrode 32 provided inside the substrate 10, and a third electrode 40 provided on the other main surface of the substrate 10 or inside the substrate 10 on the side opposite to the first electrode 22 with respect to the second electrode 32. The LC circuit includes a first capacitor C1 having one electrode connected to the signal path (main line 21), a first inductor L1 having one end connected to the signal path (main line 21), and a second capacitor C2 having one electrode connected to the first capacitor C1 and the first inductor L1 and the other electrode connected to the reference potential. The first electrode 22 and the second electrode 32 overlap at least partially when viewed in the thickness direction of the substrate 10. The second electrode 32 and the third electrode 40 overlap at least partially when viewed in the thickness direction of the substrate 10. Among the first electrode 22, the portion overlapping the second electrode 32 is one electrode of the first capacitor C1. Among the second electrode 32, the portion overlapping the first electrode 22 is the other electrode of the first capacitor C1. Among the second electrode 32, the portion overlapping the third electrode 40 is one electrode of the second capacitor C2. Among the third electrode 40, the portion overlapping the second electrode 32 is the other electrode of the second capacitor C2.

[0045] According to this, the first capacitor C1 and the second capacitor C2 are formed by the second electrode 32 and the first electrode 22 and the second electrode 32 and the third electrode 40, respectively. Therefore, compared with the case of forming electrodes on both main surfaces of the substrate 10 to form a capacitor, the area of the electrodes can be reduced without reducing the capacitance, so that a smaller filter circuit F1 can be provided.

[0046] As a desirable aspect, the capacitance of the first capacitor C1 is 0.03 pF or more. Thereby, since the capacitance of the first capacitor C1 contributes to the resonance characteristics, a signal can be attenuated at a desired attenuation pole.

[0047] Desirably, the filter circuit F1 further includes a protective film 11 provided on a part of the surface of the first electrode 22. The first electrode 22 has a region 22a at least partially with an exposed surface. Thereby, since the first electrode 22 also serves as an electrode plate of the first capacitor C1 and a connection terminal of the element 2, a smaller module 1 can be provided.

[0048] Desirably, the filter circuit F1 further includes a fourth electrode 23 provided on one main surface 10a of the substrate 10 and spaced apart from the first electrode 22 for mounting another element 2. Thereby, since the first electrode 22 also serves as an electrode plate of the first capacitor C1 and a connection terminal of the element 2, a smaller module 1 can be provided.

[0049] Desirably, the first inductor L1 is a transmission line 31 provided on or inside the main surface of the substrate 10, with one end connected to the signal path (main line 21) and the other end connected to the second electrode 32. Thereby, the filter circuit F1 can be realized with less space, so a smaller filter circuit F1 can be provided.

[0050] Desirably, the first inductor L1 is a transmission line 31 provided on or inside the main surface of the substrate 10, with one end connected to the signal path (main line 21) and the other end connected to the second electrode 32. In the thickness direction of the substrate 10, a part of the transmission line 31 overlaps with the fourth electrode 23. The width of the overlapping portion of the transmission line 31 and the fourth electrode 23 is smaller than the minimum width of the fourth electrode 23. Thereby, the occurrence of parasitics between the transmission line 31 and the fourth electrode 23 can be suppressed.

[0051] Desirably, the shape of the transmission line 31 is meander-shaped when viewed in the thickness direction of the substrate 10. Thereby, the filter circuit F1 can be realized with less space, so a smaller filter circuit F1 can be provided.

[0052] Desirably, the minimum distance in the width direction between the edge in the width direction of the transmission line 31 and the edge of the second electrode 32 is 20 μm or more. Thereby, it is possible to suppress the occurrence of parasitics between the transmission line 31 and the second electrode 32.

[0053] Desirably, the first inductor L1 is an element provided on one main surface 10a of the substrate 10. Even in this case, a small filter circuit F1 can be provided.

[0054] (Second Embodiment) FIG. 11 is a schematic diagram showing a filter circuit according to the second embodiment. As shown in FIG. 12, the filter circuit F2 according to the second embodiment is different from the first embodiment in that an element 13 is mounted as a second inductor on the main line. Hereinafter, the filter circuit F2 according to the second embodiment will be described with reference to the drawings, but the description of the same points as those in the first embodiment will be omitted.

[0055] FIG. 12 is a circuit diagram showing a filter circuit according to the second embodiment. As shown in FIG. 12, the filter circuit F2 according to the second embodiment is different from the filter circuit F1 according to the first embodiment in that a second inductor L2 is inserted into the signal path connecting the input terminal IN and the output terminal OUT. One end of the second inductor L2 is connected to a node N1 on the signal path, and the other end of the second inductor L2 is connected to a node N2 on the signal path. Even in this case, by appropriately adjusting the sum of the capacitances of the first capacitor C1 and the second capacitor C2 and the inductance of the first inductor L1, a signal can be attenuated at a desired attenuation pole by a parallel resonance circuit. Also, by inserting the second inductor L2 into the signal path connecting the input terminal IN and the output terminal OUT, the frequency of the attenuation pole can be reduced.

[0056] FIG. 13 is a schematic diagram showing the main surface of the substrate of the filter circuit according to the second embodiment. FIG. 13 is a drawing in which element 13 is removed from the filter circuit according to the second embodiment. In the second embodiment, the main line 21D includes a main line 21a and a main line 21b. In the example of FIG. 13, the main line 21a is connected to an input terminal (not shown), and the main line 21b is connected to an output terminal (not shown). In the second embodiment, the first electrode 22D is connected to one end of the main line 21b at one end in the X direction. Also, the fourth electrode 23D is connected to one end of the main line 21a at one end in the X direction. In the example of FIG. 13, the conduction via 24D is provided on the main line 21a, but this is merely an example.

[0057] FIG. 14 is a schematic diagram showing the inside of the substrate of the filter circuit according to the second embodiment. In the example of FIG. 14, one end of the transmission line 31D is connected to the conduction via 24D, and the other end is connected to the second electrode 32.

[0058] In the second embodiment, as shown in FIG. 14, the transmission line 31D overlaps with the main line 21 and the fourth electrode 23D of the first pattern 20D. In the second embodiment, similar to the third modification, the overlapping portion of the transmission line 31D and the fourth electrode 23D is smaller than the minimum length of the fourth electrode 23D. Thereby, it is possible to suppress the occurrence of parasitics between the transmission line 31D and the fourth electrode 23D.

[0059] Hereinafter, the connection between the main line 21 and the element 13 and the protective film 11A in the filter circuit F2 according to the second embodiment will be described in detail. In FIGS. 11 and 13, the region where the protective film 11 is provided is shown as a shaded region.

[0060] In the example of FIG. 13, the protective film 11 further has a protective film 11c provided on the fourth electrode 23D. The protective film 11c is provided in a frame shape so as to overlap the edge of the fourth electrode 23D in a plan view in the Z direction, similar to the protective film 11a with respect to the first electrode 22D. Here, the fourth electrode 23D has a region 23Da where at least a part of the surface of the fourth electrode 23D is exposed from the protective film 11. In the example of FIG. 13, a conductive bonding material is disposed in the region 23Da, similar to the region 22Da of the first electrode 22D, and the element is connected to the fourth electrode 23D via the conductive bonding material in the region 23Da.

[0061] In the second embodiment, the region 22Da is on the fourth electrode side of the first electrode 22D in a plan view in the Z direction. More specifically, in a plan view in the Z direction, the fourth electrode 23D is in the direction of the geometric center of the region 22Da with respect to the geometric center of the first electrode 22D. Thereby, in a plan view in the Z direction, the area of the region where the element 13 and the first electrode 22D overlap can be reduced, so that the generation of parasitic components in the element 13 and the first electrode 22D can be suppressed.

[0062] In the second embodiment, similar to the region 22Da, the region 23Da is on the fourth electrode side of the fourth electrode 23D in a plan view in the Z direction. More specifically, in a plan view in the Z direction, the first electrode 22D is in the direction of the geometric center of the region 23Da with respect to the geometric center of the fourth electrode 23D. Thereby, in a plan view in the Z direction, the area of the region where the element 13 and the fourth electrode 23D overlap can be reduced, so that the generation of parasitic components in the element 13 and the fourth electrode 23D can be suppressed.

[0063] As described above, the filter circuit F2 according to the second embodiment has been described. However, the filter according to the second embodiment is not limited to those shown in FIGS. 11 to 14. Hereinafter, modified examples will be described with reference to the drawings.

[0064] (Fourth Modified Example) FIG. 15 is a schematic diagram showing a main surface of a substrate of a filter circuit according to a fourth modification. FIG. 16 is a schematic diagram showing the inside of a substrate of a filter circuit according to a fourth modification. As shown in FIG. 15, in the filter circuit according to the fourth modification, the transmission line 31E is an L-shaped line, and the areas of the electrodes of the first capacitor C1 and the second capacitor C2, that is, the area of the first electrode 22E and a second electrode (not shown) are increased. In this case, instead of reducing the inductance of the transmission line 31E, that is, the first inductor L1, the capacitance of the first capacitor C1 increases. Therefore, even in this case, an electrical signal can be attenuated at a specific frequency (attenuation pole) thereby.

[0065] As described above, the filter circuit according to the second embodiment is a filter circuit further having a second inductor L2 inserted into a signal path (main line 21D) between one electrode of the first capacitor C1 and the first inductor L1. Another element 13 is the second inductor L2. Even in this case, a small-sized filter circuit can be provided.

[0066] Desirably, when viewed in the thickness direction of the substrate, the fourth electrode 23D is provided in a direction toward the geometric center of the region 22Da with respect to the geometric center of the first electrode 22D. Thereby, it is possible to suppress the occurrence of parasitics between the another element 13 and the fourth electrode 23D.

[0067] Note that the above-described embodiments are for facilitating the understanding of the present disclosure, and are not for limiting the interpretation of the present invention. The present disclosure can be changed / improved without departing from the gist thereof, and equivalents thereof are also included in the present disclosure.

[0068] As described above or instead of the above, the present disclosure can take the following configuration.

[0069] (1) A filter circuit having an LC circuit, one end of which is connected to a signal path connecting an input terminal and an output terminal, and the other end of which is connected to a reference potential, a substrate, A first electrode provided on one main surface of the substrate, A second electrode provided inside the substrate, A third electrode provided on the other main surface of the substrate or inside the substrate on the side opposite to the first electrode with respect to the second electrode, Comprising, The LC circuit is, A first capacitor having one electrode connected to the signal path, A first inductor having one end connected to the signal path, A second capacitor having one electrode connected to the first capacitor and the first inductor and the other electrode connected to a reference potential, Including, The first electrode and the second electrode overlap at least partially when viewed in the thickness direction of the substrate, The second electrode and the third electrode overlap at least partially when viewed in the thickness direction of the substrate, Among the first electrodes, the portion overlapping the second electrode is one electrode of the first capacitor, Among the second electrodes, the portion overlapping the first electrode is the other electrode of the first capacitor, Among the second electrodes, the portion overlapping the third electrode is one electrode of the second capacitor, Among the third electrodes, the portion overlapping the second electrode is the other electrode of the second capacitor, a filter circuit. (2) The capacitance of the first capacitor is 0.03 pF or more, the filter circuit according to (1). (3) Further comprising a protective film provided on a part of the surface of the first electrode, The first electrode has a region where the surface is exposed from the protective film at least partially, the filter circuit according to (1) or (2). (4) An electrode for mounting another element, further comprising a fourth electrode provided on one main surface of the substrate and separated from the first electrode, the filter circuit according to (3). (5) A filter circuit further having a second inductor inserted into the signal path between one electrode of the first capacitor and the first inductor, The filter circuit according to (4), wherein the another element is the second inductor. (6) The filter circuit according to (4) or (5), wherein, when viewed in the thickness direction of the substrate, the fourth electrode is provided in a direction toward the geometric center of the region with respect to the geometric center of the first electrode. (7) The first inductor is a transmission line provided on the main surface or inside of the substrate, having one end connected to the signal path and the other end connected to the second electrode, In the thickness direction of the substrate, a part of the transmission line overlaps with the fourth electrode, The filter circuit according to any one of (4) to (6), wherein the width of the portion of the transmission line overlapping with the fourth electrode is smaller than the minimum width of the fourth electrode. (8) The filter circuit according to any one of (1) to (6), wherein the first inductor is a transmission line provided on the main surface or inside of the substrate, having one end connected to the signal path and the other end connected to the second electrode. (9) The filter circuit according to (7) or (8), wherein the shape of the transmission line is meander-shaped when viewed in the thickness direction of the substrate. (10) The filter circuit according to any one of (7) to (9), wherein the minimum distance in the width direction between the edge in the width direction of the transmission line and the edge of the second electrode is 20 μm or more. (11) The filter circuit according to any one of (1) to (6), wherein the first inductor is an element provided on the one main surface of the substrate.

[0070] According to the present disclosure, a filter circuit capable of obtaining desired filter characteristics can be realized.

Description of Reference Numerals

[0071] 1 Module 2 Element 3 Conductive bonding material 10 Substrate 10a Main surface 11 Protective film 12, 13 Element 20 First pattern 21 Main line 22 First electrode 23 Fourth electrode 24 Conductive via 25 Electrode 30 Second pattern 31 Transmission line 32 Second electrode 40 Third electrode F1, F2 Filter circuit C1 First capacitor C2 Second capacitor L1 First inductor L2 Second inductor N1 Node N2 Node

Claims

1. A filter circuit having an LC circuit with one end connected to a signal path connecting an input terminal and an output terminal and the other end connected to a reference potential, comprising: a substrate; a first electrode provided on one main surface of the substrate; a second electrode provided inside the substrate; a third electrode provided on the other main surface of the substrate or inside the substrate on the side opposite to the first electrode with respect to the second electrode; and comprising: The LC circuit includes: a first capacitor having one electrode connected to the signal path; a first inductor having one end connected to the signal path; a second capacitor having one electrode connected to the first capacitor and the first inductor and the other electrode connected to a reference potential; and including: The first electrode and the second electrode overlap at least partially when viewed in the thickness direction of the substrate; The second electrode and the third electrode overlap at least partially when viewed in the thickness direction of the substrate; Of the first electrode, the portion overlapping the second electrode is one electrode of the first capacitor; Of the second electrode, the portion overlapping the first electrode is the other electrode of the first capacitor; Of the second electrode, the portion overlapping the third electrode is one electrode of the second capacitor; Of the third electrode, the portion overlapping the second electrode is the other electrode of the second capacitor. A filter circuit.

2. The filter circuit according to claim 1, wherein the capacitance of the first capacitor is 0.03 pF or more.

3. Further comprising a protective film provided on a part of the surface of the first electrode, The filter circuit according to claim 1, wherein the first electrode has a region where at least a part of the surface is exposed from the protective film.

4. The filter circuit according to claim 3, further comprising a fourth electrode provided on one main surface of the substrate, spaced apart from the first electrode, for mounting another element.

5. A filter circuit further having a second inductor inserted into the signal path between one electrode of the first capacitor and the first inductor, The filter circuit according to claim 4, wherein the another element is the second inductor.

6. The filter circuit according to claim 4, wherein when viewed in the thickness direction of the substrate, the fourth electrode is provided in a direction toward the geometric center of the region with respect to the geometric center of the first electrode.

7. The first inductor is a transmission line provided on the main surface or inside of the substrate, with one end connected to the signal path and the other end connected to the second electrode, and in the thickness direction of the substrate, a part of the transmission line overlaps with the fourth electrode, The width of the portion of the transmission line that overlaps with the fourth electrode is smaller than the minimum width of the fourth electrode. The filter circuit according to claim 4.

8. The first inductor is a transmission line provided on the main surface or inside of the substrate, with one end connected to the signal path and the other end connected to the second electrode. The filter circuit according to claim 1.

9. The shape of the transmission line is meander-shaped when viewed in the thickness direction of the substrate. The filter circuit according to claim 7 or 8.

10. The minimum distance in the width direction between the edge in the width direction of the transmission line and the edge of the second electrode is 20 μm or more. The filter circuit according to claim 7 or 8.

11. The first inductor is an element provided on the one main surface of the substrate. The filter circuit according to claim 1.

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