Filter device and antenna device

Abstract

The present disclosure provides a filter device capable of obtaining good characteristics even when an attenuation band based on parallel resonance is brought close to a passband based on series resonance. A filter device (100) according to the present disclosure is provided with: a first terminal (P1); a second terminal (P2); a first inductor (L1); and a series resonator (RS) disposed in the first path (TL1) among the first path (TL1) and the second path (TL2) provided in parallel. The series resonator (RS) includes: a second inductor (L2); a capacitor (C2) connected in series with the second inductor (L2); and a third inductor (L3) connected in series with the second inductor (L2) and the capacitor (C1). The magnetic coupling of the first inductor (L1) with the third inductor (L3) is weaker than the magnetic coupling of the first inductor (L1) with the second inductor (L2).

Description

Technical Field

[0001] This disclosure relates to a filter device and an antenna device. Background Technology

[0002] High-frequency circuits include filter devices such as band-stop filters and band-pass filters. As an example of a filter device installed in a high-frequency circuit, Japanese Patent No. 6531824 (Patent Document 1) discloses a filter device. This filter device includes a first inductor and a first capacitor forming a first series circuit, and a second inductor connected in parallel with the first series circuit.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6531824 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, in the filter device disclosed in Japanese Patent No. 6531824 (Patent Document 1), it is difficult to maintain both the attenuation characteristics and the passband characteristics as high when the attenuation band (attenuation pole) based on parallel resonance is close to that based on series resonance.

[0008] This disclosure was made to solve such a problem, and its purpose is to provide a filter device that can obtain good characteristics even when the attenuation band based on parallel resonance is close to that based on series resonance.

[0009] Solution for solving the problem

[0010] The filter device disclosed herein is a filter device with an attenuation frequency band. The filter device includes: a first terminal; a second terminal; a first inductor connected to the first terminal; and a series resonator disposed in the first path of a first path and a second path connected in parallel between the first inductor and the second terminal. The series resonator includes: a second inductor; a capacitor connected in series with the second inductor; and a third inductor connected in series with the second inductor and the capacitor. The magnetic coupling between the first inductor and the third inductor is weaker than the magnetic coupling between the first inductor and the second inductor.

[0011] The antenna device disclosed herein is an antenna device capable of radiating radio waves. The antenna device includes: a radiating element; a feeding circuit that provides a high-frequency signal to the radiating element; and the aforementioned filter device disposed between the antenna and the feeding circuit.

[0012] The effects of the invention

[0013] In the filter device disclosed herein, a series resonator is configured in the first path, and the first inductor and the second inductor are magnetically coupled to each other. Therefore, high attenuation characteristics and pass-through characteristics can be obtained even when the attenuation band based on parallel resonance and the pass-through band based on series resonance are close. Attached Figure Description

[0014] Figure 1 This is a perspective view of the filter device according to Embodiment 1.

[0015] Figure 2 This is a circuit diagram of the filter device and antenna device involved in Embodiment 1.

[0016] Figure 3 This is a diagram used to illustrate the attenuation characteristics of a filter device.

[0017] Figure 4 This is an exploded top view showing the structure of the filter device according to Embodiment 1.

[0018] Figure 5 This is a perspective view of the filter device involved in Embodiment 2.

[0019] Figure 6 This is an exploded top view showing the structure of the filter device according to Embodiment 2.

[0020] Figure 7 This is a graph showing the attenuation characteristics of the filter device according to Embodiment 2.

[0021] Figure 8 This is a perspective view of the filter device involved in Embodiment 3.

[0022] Figure 9 This is an exploded top view showing the structure of the filter device according to Embodiment 3.

[0023] Figure 10 This is a graph showing the attenuation characteristics of the filter device according to Embodiment 3.

[0024] Figure 11 This is the circuit diagram of the antenna device involved in Variation Example 1.

[0025] Figure 12 This is the circuit diagram of the antenna device involved in Variation Example 2.

[0026] Figure 13 This is the circuit diagram of the antenna device involved in Variation Example 3. Detailed Implementation

[0027] The filter device according to the embodiment will now be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0028] (Implementation Method 1)

[0029] [Filter Device Construction]

[0030] First, the filter device according to Embodiment 1 will be described with reference to the accompanying drawings. Figure 1 This is a perspective view of the filter device 100 according to Embodiment 1. Here, in Figure 1 In this context, the short side direction of the filter device 100 is set as the X direction, the long side direction is set as the Y direction, and the height direction is set as the Z direction.

[0031] The filter device 100 is a cuboid-shaped chip component formed by stacking two inductors and one capacitor in the Z direction. For example... Figure 1 As shown, the filter device 100 is composed of an insulator 3 formed by stacking multiple insulating substrates (insulator layers) on which a first conductor pattern of a first inductor L1, a second conductor pattern of a second inductor L2, and an electrode pattern of a capacitor C1 are formed. Furthermore, the stacking direction of the insulating substrates is the Z direction, and the arrow indicates the direction of the upper layer. Additionally, the insulating substrates are made of materials such as insulating materials with borosilicate glass as the main component, alumina, zirconium oxide, polyimide resin, etc. Moreover, in the insulator 3, sometimes the interfaces between the multiple insulating substrates become unclear through processes such as firing and curing.

[0032] In addition, the filter device 100 has two portions formed in the Y direction of the insulator 3. Figure 1 The external electrode 4a (first external electrode) and external electrode 4b (second external electrode) are shown as shown. Furthermore, the insulator 3 has a pair of main surfaces facing each other. Figure 1 The lower main surface is the mounting surface, which faces the circuit board. In this embodiment 1, it will also... Figure 1 The lower side of the main surface is called the bottom surface. Figure 1 The upper side of the main surface is called the top surface.

[0033] The external electrodes 4a and 4b are not only formed with electrode patterns on the bottom surface of the insulator 3, but also on the side surfaces of the insulator 3 that connect the main surfaces. When the insulator 3 is viewed from the side surface (XZ plane) on the short side, the external electrodes 4a and 4b are U-shaped. Therefore, the external electrodes 4a provided on each of the opposing side surfaces (first side surface and second side surface) of the insulator 3 have the same potential due to the electrode patterns provided on the bottom surface of the insulator 3. Similarly, the external electrodes 4b provided on each of the opposing side surfaces of the insulator 3 have the same potential due to the electrode patterns provided on the bottom surface of the insulator 3.

[0034] The first conductor pattern 1a (first conductor pattern) of the first inductor L1 is electrically connected to the external electrode 4a via wiring pattern 11a on the side of the insulator 3. On the other hand, the electrode pattern 5b (second electrode pattern) of the capacitor C1 is connected to the external electrode 4b via wiring pattern 51a (see reference 11a). Figure 4 ) and wiring pattern 51b are electrically connected on the side of the insulator 3.

[0035] In the first inductor L1, multiple first conductor patterns 1a-1d are stacked parallel to the main surface of the insulator 3, and each first conductor pattern 1a-1d is electrically connected through through-hole conductors 31 and 32. The first conductor patterns 1a and 1c are electrically connected to the external electrode 4a via wiring patterns 11a and 11c on the side surface (first side surface) of the insulator 3. The first conductor patterns 1b and 1d are electrically connected to the external electrode 4b via wiring patterns 11b and 11d on the side surface (second side surface) of the insulator 3.

[0036] In the second inductor L2, multiple second conductor patterns 2a-2d are stacked parallel to the main surface of the insulator 3, and each second conductor pattern 2a-2d is electrically connected through through-hole conductors 33-36. The second conductor pattern 2a is electrically connected to the external electrode 4b via wiring pattern 21e on the side surface (second side surface) of the insulator 3.

[0037] In capacitor C1, multiple electrode patterns 5a~5c are stacked on the lower layer of the second inductor L2, separated by an insulating layer. The second conductor pattern 2d of the second inductor L2 (see reference) Figure 4 Electrode pattern 5a of capacitor C1 is electrically connected to the external electrode 4b via through-hole conductor 39. Electrode pattern 5b is not electrically connected to the external electrode 4b or other wiring patterns, and is a floating electrode. Electrode pattern 5c is electrically connected to the external electrode 4b on two opposing sides (the first side and the second side) of the insulator 3 via wiring pattern 51c. Furthermore, electrode pattern 5c is electrically connected to the external electrode 4b via through-hole conductor 41.

[0038] Furthermore, in the filter device 100, the path from the wiring patterns 11b and 11d at one end of the first inductor L1, through the external electrode 4b on the side (first side) of the insulator 3, the electrode pattern 5c of the capacitor C1, the external electrode 4b on the side (second side) of the insulator 3, and to the wiring pattern 21e at one end of the second inductor L2 constitutes the third inductor L3. The opening surfaces of the first inductor L1 and the second inductor L2 forming the coil are formed parallel to the XY plane, and their openings overlap when viewed from the top side. Therefore, the first inductor L1 and the second inductor L2 have strong magnetic coupling. On the other hand, the opening surface of the third inductor L3 forming the coil is formed on the XZ plane. Therefore, the magnetic coupling between the first inductor L1 and the third inductor L3 does not occur or is weaker than the magnetic coupling between the first inductor L1 and the second inductor L2.

[0039] The second inductor L2, the third inductor L3, and the capacitor C1 are connected in series within the insulator 3 to form an LC series resonator. Therefore, the filter device 100 generates attenuation poles and has a resonant frequency through the LC series resonator. Next, the circuit structure of the filter device 100 and the antenna device using the filter device 100 will be described in detail.

[0040] Figure 2 This is a circuit diagram of the filter device and antenna device involved in Embodiment 1. Figure 2 (a) is a circuit diagram of the filter device 100 according to Embodiment 1. Figure 2 (b) is a circuit diagram of the antenna device 150 in Embodiment 1. The filter device 100 is used in the antenna device 150 and is a notch filter that blocks and attenuates high-frequency signals in a specific frequency band. The filter device 100 is also referred to as a band-stop filter.

[0041] Antenna device 150 includes a feed circuit RF1, a filter device 100, and a radiating element 155. Antenna device 150 can be mounted, for example, on portable terminals such as mobile phones, smartphones or tablets, or communication devices such as personal computers with communication functions.

[0042] The feed circuit RF1 provides a high-frequency signal in the f1 band to the radiating element 155. The radiating element 155 is, for example, a monopole antenna, capable of radiating the high-frequency signal in the f1 band provided by the feed circuit RF1 as a radio wave into the air.

[0043] When using antenna device 150 near an antenna, for example, in the f0 band (≠ f1 band), a filter device 100 is useful for attenuating high-frequency signals in the f0 band and allowing high-frequency signals in the f1 band to pass through. In filter device 100, the attenuation band (attenuation pole) based on parallel resonance is the f0 band, and the passband based on series resonance is the f1 band.

[0044] Specifically, such as Figure 2 As shown in (a), the filter device 100 has terminals P1 and P2. Terminal P1 is used to connect the filter device 100 to the transmission line on the feed circuit RF1 side. Terminal P2 is used to connect the filter device 100 to the transmission line on the radiating element 155 side. Furthermore, terminal P1 (the first terminal) and... Figure 1 The external electrode 4a shown corresponds to terminal P2 (second terminal) and Figure 1 The external electrode 4b shown corresponds to this.

[0045] Furthermore, when the power supply circuit RF1 provides a high-frequency signal to the radiating element 155 via the filter device 100, terminal P1 becomes an input terminal and terminal P2 becomes an output terminal. When the high-frequency signal received by the radiating element 155 is transmitted to the circuit on the power supply circuit RF1 side via the filter device 100, terminal P1 becomes an output terminal and terminal P2 becomes an input terminal.

[0046] like Figure 2 As shown in (a), the filter device 100 includes a first inductor L1, a second inductor L2, a third inductor L3, and a capacitor C1. A first path TL1 and a second path TL2 are provided between the first inductor L1 and terminal P2. An LC series resonator RS is provided in the first path TL1, connecting the third inductor L3, the second inductor L2, and the capacitor C1 in series. The second path TL2 is a short-circuit path.

[0047] The first inductor L1 and the second inductor L2 are magnetically coupled to each other, but the first inductor L1 and the third inductor L3 are not magnetically coupled to each other. Therefore, a mutual inductance M is generated between the first inductor L1 and the second inductor L2, but no mutual inductance M is generated between the first inductor L1 and the third inductor L3. Through the mutual inductance M generated between the first inductor L1 and the second inductor L2, inductances are generated in the first path TL1 and the second path TL2 respectively, forming a parallel resonator. Furthermore, the first inductor L1 and the third inductor L3 are not limited to having no magnetic coupling at all; they can also have a weaker magnetic coupling than the magnetic coupling between the first inductor L1 and the second inductor L2.

[0048] In a filter device 100, where the first path TL1 has an LC series resonator RS and the first path TL1 and the second path TL2 form a parallel resonator, the resonant frequency of the parallel resonator coincides with the series resonant frequency f0 of the LC series resonator RS, becoming the parallel resonant frequency of the attenuation band (f0 segment) of the filter device 100. The series resonant frequency f0 of the LC series resonator RS is determined by the inductance of the inductors (second inductor L2, third inductor L3) and the capacitance of the capacitor (capacitor C1) constituting the LC series resonator RS. Therefore, for example, if it is desired to adjust the attenuation band (f0 segment) of the filter device 100 to the low-frequency side, it is necessary to increase the size of the inductors constituting the LC series resonator RS.

[0049] However, when the inductance of the second inductor L2, which is magnetically coupled to the first inductor L1, is increased, Figure 1 In the configuration of the filter device 100 shown, it is necessary to further add a layer having a second conductive pattern formed as part of the second inductor L2. By adding a layer with the second conductive pattern without changing the size of the filter device 100, the distance between the first inductor L1 and the second inductor L2 becomes closer, and the coupling coefficient k undesirably increases. In the filter device 100, by reducing the coupling coefficient k, the series resonant frequency (center frequency) can be made closer to the parallel resonant frequency (center frequency), but conversely, when the coupling coefficient k increases, the width of the attenuation pole becomes wider. Therefore, if the coupling coefficient k increases, it is difficult to realize a small filter device with a steep attenuation pole in the low-frequency band.

[0050] Here, we explain the relationship between the parameters of the first inductor L1 and the second inductor L2 of the filter device and the attenuation characteristics of the filter device. Figure 3 This is a diagram used to illustrate the attenuation characteristics of a filter device. In Figure 3 In the graph, the horizontal axis represents frequency, and the vertical axis represents attenuation characteristics, showing that the attenuation increases towards the bottom of the graph. Figure 3 The diagram illustrates the attenuation characteristics of a filter device with an attenuation pole at a certain resonant frequency f0. The frequency f0 can be adjusted by changing the inductance of the second inductor L2 or the capacitance of the capacitor C1. That is, to adjust the resonant frequency f0 to a lower frequency side, the inductance of the second inductor L2 or the capacitance of the capacitor C1 can be increased. However, increasing the capacitance of the capacitor C1, without changing the dimensions of the filter device, increases the area where the openings of the first inductor L1 and the second inductor L2 overlap with the electrodes of the capacitor C1 when viewed from the top, potentially hindering magnetic flux.

[0051] Furthermore, if the coupling coefficient k is increased, the value of the attenuation pole at the resonant frequency f0 becomes smaller (the attenuation pole becomes deeper), thus widening the width of the attenuation pole. Specifically, the attenuation characteristic of the filter device with a certain coupling coefficient k is curve I, while when the coupling coefficient k is increased, the attenuation characteristic of the filter device changes to curve II, and the width of the attenuation pole becomes wider.

[0052] The width of the attenuation pole also varies depending on the Q value of the second inductor L2. Specifically, the attenuation characteristic of the filter device with a certain Q value for the second inductor L2 is curve I, while when the Q value of the second inductor L2 is increased, the attenuation characteristic of the filter device changes to curve III, and the width of the attenuation pole narrows. On the other hand, the inductance of the first inductor L1 affects the throughput characteristics at all frequencies. When the inductance of the first inductor L1 is reduced, especially in the high-frequency band at the resonant frequency f0, the throughput is affected by losses. Figure 3 The direction of the arrow shown has been improved.

[0053] In the filter device 100, considering the above-described relationship, by providing a third inductor L3, which is not magnetically coupled to the first inductor L1, instead of the second inductor L2, the inductance of the inductors constituting the LC series resonator RS can be increased. Therefore, in the filter device 100, the resonant frequency f0 can be reduced without changing the coupling coefficient k between the first inductor L1 and the second inductor L2, thus realizing a filter device with a steep attenuation pole in the low frequency band.

[0054] [Exploded top view of the filter device]

[0055] Next, the structure of each layer is explained using exploded top views. Figure 4 This is an exploded top view showing the structure of the filter device 100 according to Embodiment 1. First, as... Figure 4 As shown, the first conductor patterns 1a~1d, the second conductor patterns 2a~2d, the wiring patterns 11a~11b, 21e, 51c, 52c, 52~56 and the electrode patterns 5a~5c are respectively formed on the insulating substrates 3a~3n by printing.

[0056] A first conductor pattern 1a, constituting a part of the first inductor L1, is formed on the insulating substrate 3a. The first conductor pattern 1a is a hexagonal pattern that rotates approximately one revolution counterclockwise from the lower left side of the insulating substrate 3a. The beginning of the first conductor pattern 1a is connected to the external electrode 4a (see figure) via a wiring pattern 11a. Figure 1 Electrical connection. A connection portion 31a connected to the through-hole conductor 31 is provided near the end of the first conductor pattern 1a, and a connection portion 32a connected to the through-hole conductor 32 is provided in the middle of the first conductor pattern 1a.

[0057] A first conductor pattern 1b, constituting a part of the first inductor L1, is formed on the insulating substrate 3b. The first conductor pattern 1b is a hexagonal pattern that rotates approximately one full turn clockwise from the lower right side of the insulating substrate 3b. The beginning of the first conductor pattern 1b is connected to the external electrode 4b (see figure) via a wiring pattern 11b. Figure 1 Electrical connection. A connection portion 31b for connecting to the through-hole conductor 31 is provided near the end of the first conductor pattern 1b, and a connection portion 32b for connecting to the through-hole conductor 32 is provided in the middle of the first conductor pattern 1b.

[0058] A first conductor pattern 1c, constituting a part of the first inductor L1, is formed on the insulating substrate 3c. The first conductor pattern 1c has the same shape as the first conductor pattern 1a, forming a hexagonal pattern that rotates approximately one revolution counterclockwise from the lower left side of the insulating substrate 3c. The beginning of the first conductor pattern 1c is connected to the external electrode 4a (see figure) via a wiring pattern 11c. Figure 1 Electrical connection. A connection portion 31c connected to the through-hole conductor 31 is provided near the end of the first conductor pattern 1c, and a connection portion 32c connected to the through-hole conductor 32 is provided in the middle of the first conductor pattern 1c.

[0059] A first conductor pattern 1d, constituting a part of the first inductor L1, is formed on the insulating substrate 3d. The first conductor pattern 1d has the same shape as the first conductor pattern 1b, forming a hexagonal pattern that rotates approximately one revolution clockwise from the lower right side of the insulating substrate 3d. The beginning of the first conductor pattern 1d is connected to the external electrode 4b (see figure) via a wiring pattern 11d. Figure 1 Electrical connection. A connection portion 31d connected to the through-hole conductor 31 is provided near the end of the first conductor pattern 1d, and a connection portion 32d connected to the through-hole conductor 32 is provided in the middle of the first conductor pattern 1d.

[0060] The first inductor L1 is configured such that first conductor patterns 1a and 1c and first conductor patterns 1b and 1d are connected in parallel, and the first conductor patterns 1a and 1c connected in parallel are connected in series with the first conductor patterns 1b and 1d connected in parallel, thereby connecting two coils of approximately one turn in parallel.

[0061] A second conductor pattern 2a, constituting part of the second inductor L2, is formed on the insulating substrate 3e. The second conductor pattern 2a forms an L-shape, rotating approximately 1 / 2 turn counterclockwise from the upper right side of the insulating substrate 3e. The beginning of the second conductor pattern 2a is connected to the external electrode 4b (see figure) via a wiring pattern 21e. Figure 1 Electrical connection. A connection portion 33a that connects to the through-hole conductor 33 is provided near the end of the second conductor pattern 2a.

[0062] A second conductor pattern 2b, constituting a part of the second inductor L2, is formed on the insulating substrate 3f. The second conductor pattern 2b forms a U-shaped pattern that rotates counterclockwise approximately 3 / 4 of a turn from the lower left side of the insulating substrate 3f in the figure. A connection portion 33b for connecting to the through-hole conductor 33 is provided near the beginning of the second conductor pattern 2b, a connection portion 34a for connecting to the through-hole conductor 34 is provided near the end of the second conductor pattern 2b, and a connection portion 35a for connecting to the through-hole conductor 35 is provided in the middle of the second conductor pattern 2b.

[0063] A second conductor pattern 2c, constituting a part of the second inductor L2, is formed on the insulating substrate 3g. The second conductor pattern 2c forms a U-shaped pattern that rotates counterclockwise approximately 3 / 4 of a turn from the upper center of the insulating substrate 3g. A connection portion 35b, connecting to a through-hole conductor 35, is provided near the beginning of the second conductor pattern 2c; a connection portion 36a, connecting to a through-hole conductor 36, is provided near the end of the second conductor pattern 2c; and a connection portion 34b, connecting to a through-hole conductor 34, is provided in the middle of the second conductor pattern 2c.

[0064] A second conductor pattern 2d, constituting a part of the second inductor L2, is formed on the insulating substrate 3h. The second conductor pattern 2d forms an "I" shape extending upward from the lower right side of the insulating substrate 3h. A connection portion 36b, which connects to the through-hole conductor 36, is provided near the beginning of the second conductor pattern 2d, and a connection portion 37a, which connects to the through-hole conductor 37, is provided near the end of the second conductor pattern 2d.

[0065] In the second inductor L2, second conductor patterns 2a to 2d are connected in series to form a coil of approximately two turns. Viewed from the top, the opening of the second inductor L2 is rectangular, while the opening of the first inductor L1 is hexagonal. By making the opening of the second inductor L2 rectangular, the inductance of the second inductor L2 can be increased by effectively utilizing the space within the insulator 3. On the other hand, by making the opening of the first inductor L1 hexagonal, the area overlapping the opening of the second inductor L2 when viewed from the top can be changed, allowing adjustment of the coupling coefficient k. Furthermore, by making the opening of the first inductor L1 hexagonal, the inductance of the first inductor L1 can be reduced, thus improving the throughput characteristics of the filter device 100. Moreover, the shape of the opening of the first inductor L1 is not limited to hexagon; it can be any shape other than a rectangle, such as an octagon or a polygon.

[0066] An electrode pattern 5a (first electrode pattern) constituting one electrode of capacitor C1 is formed on the insulating substrate 3i. Viewed from the top surface, the electrode pattern 5a is located on the right side within the insulator 3. That is, the electrode pattern 5a is positioned to avoid overlapping with the openings of the first inductor L1 and the second inductor L2 as much as possible. The electrode pattern 5a has a connection portion 37b that connects to the through-hole conductor 37.

[0067] An electrode pattern 5b is formed on the insulating substrate 3j. Viewed from the top surface, the electrode pattern 5b is positioned overlapping the electrode pattern 5a. The electrode pattern 5b is not adjacent to the external electrode 4b (see reference). Figure 1 The electrical connection is the floating electrode of capacitor C1.

[0068] An electrode pattern 5c constituting another electrode of capacitor C1 is formed on insulating substrate 3k. Viewed from the top side, electrode pattern 5c is positioned opposite electrode pattern 5b. Electrode pattern 5c is connected to the external electrodes 4b on the two opposing sides (see reference 51c) via wiring pattern 51c. Figure 1 Electrical connection. The electrode pattern 5c has a connection portion 39a that connects to the through-hole conductor 39. Furthermore, on the insulating substrate 3k, when viewed from the top side, a wiring pattern 52 is provided on the left side within the insulator 3. The wiring pattern 52 connects to the external electrodes 4a on two opposing sides (see reference 39) via the wiring pattern 52c. Figure 1 Electrical connection. Additionally, wiring pattern 52 has a connection portion 38a that connects to the through-hole conductor 38.

[0069] Regarding capacitor C1, it is constructed using electrode patterns 5a, 5b, and 5c. Insulating substrates 31 to 3n are also provided on the lower layer of capacitor C1. Insulating substrate 31 has a wiring pattern 53 with a connection portion 38b connected to a through-hole conductor 38, and a wiring pattern 54 with a connection portion 39b connected to a through-hole conductor 39 and a connection portion 41a connected to a through-hole conductor 41. Insulating substrate 3m has a wiring pattern 55 with a connection portion 38c connected to a through-hole conductor 38, and a wiring pattern 56 with a connection portion 41b connected to a through-hole conductor 41. Insulating substrate 3n has a connection portion 38d connected to a through-hole conductor 38 and a connection portion 41c connected to a through-hole conductor 41. The through-hole conductor 38 is electrically connected to an external electrode 4a on the bottom surface via connection portion 38d, and the through-hole conductor 41 is electrically connected to an external electrode 4b on the bottom surface via connection portion 41c.

[0070] (Implementation Method 2)

[0071] In the filter device 100 according to Embodiment 1, a path is described that forms the third inductor L3, starting from the wiring patterns 11b, 11d provided at one end of the first inductor L1, passing through the external electrode 4b on the side of the insulator 3, the electrode pattern 5c of the capacitor C1, the external electrode 4b on the side of the insulator 3, and reaching the wiring pattern 21e provided at one end of the second inductor L2. In Embodiment 2, the structure of the filter device is described when an inductance smaller than that of the third inductor L3 according to Embodiment 1 is added.

[0072] [Filter Device Construction]

[0073] First, the filter device according to Embodiment 2 will be described with reference to the accompanying drawings. Figure 5 This is a perspective view of the filter device 200 according to Embodiment 2. Here, in Figure 5 In this design, the short side direction of the filter device 200 is defined as the X direction, the long side direction as the Y direction, and the height direction as the Z direction. Furthermore, in... Figure 5 In the filter device 200 shown, for the filter with Figure 1 The filter device 100 shown has the same structure and is labeled with the same reference numerals, and detailed descriptions are not repeated.

[0074] The filter device 200 is a cuboid-shaped chip component formed by stacking two inductors and one capacitor in the Z direction. For example... Figure 5 As shown, the filter device 200 is composed of an insulator 3 formed by stacking multiple insulating substrates (insulator layers) having a first conductor pattern of a first inductor L1, a second conductor pattern of a second inductor L2, and an electrode pattern of a capacitor C1. The structures of the first inductor L1 and the capacitor C1 in the filter device 200 are similar to... Figure 1 The filter device 100 shown is the same, but the structure of the second inductor L2 is different.

[0075] In the second inductor L2, multiple second conductor patterns 2a-2d are stacked parallel to the main surface of the insulator 3, and each second conductor pattern 2a-2d is electrically connected through through-hole conductors 33-36. The second conductor pattern 2a is electrically connected to the external electrode 4b via a wiring pattern 22e on the side surface (first side surface) of the insulator 3. On the other hand, the second conductor pattern 2a is not electrically connected to the external electrode 4a.

[0076] Therefore, in the filter device 200, the path from the wiring patterns 11b, 11d provided at one end of the first inductor L1, through the external electrode 4b on the side (first side) of the insulator 3, and to the wiring pattern 22e provided at one end of the second inductor L2 constitutes the third inductor L3. Regarding the third inductor L3, the inductor is formed solely by the external electrode 4b provided on one side of the insulator 3, thus... Figure 1 Compared to the case where the inductor is formed by external electrodes 4b disposed on both sides of the insulator 3, the inductance is smaller. Figure 5 The opening of the third inductor L3 shown is also formed on the XZ plane. Therefore, the magnetic coupling between the first inductor L1 and the third inductor L3 is weaker than the magnetic coupling between the first inductor L1 and the second inductor L2.

[0077] The second inductor L2, the third inductor L3, and the capacitor C1 are connected in series within the insulator 3 to form an LC series resonator. Therefore, the filter device 200 generates attenuation poles through the LC series resonator and has a resonant frequency.

[0078] [Exploded top view of the filter device]

[0079] Next, the structure of each layer is explained using exploded top views. Figure 6 This is an exploded top view showing the structure of the filter device 200 according to Embodiment 2. Furthermore, in Figure 6 In the middle, the filter device 200, except for the structure of the second inductor L2, is similar to... Figure 1 Except for the filter device 100 shown, the structure is the same, therefore in Figure 6 The exploded top view of capacitor C1 is omitted. The same reference numerals are used to label the same structures, and detailed descriptions are not repeated.

[0080] A second conductor pattern 2a, constituting part of the second inductor L2, is formed on the insulating substrate 3e. The second conductor pattern 2a forms an L-shape, rotating approximately 1 / 2 turn clockwise from the lower right side of the insulating substrate 3e. The beginning of the second conductor pattern 2a is connected to the external electrode 4b (see figure) via a wiring pattern 22e. Figure 5 Electrical connection. A connection portion 33a, connecting to the through-hole conductor 33, is provided midway at the end of the second conductor pattern 2a. In the second conductor pattern 2a and the second conductor pattern 2b, the current flows in opposite directions, and the inductance value of the second inductor L2 decreases. Alternatively, the second conductor pattern 2a can be made not L-shaped, but passing through the top of the figure and connecting to the wiring pattern 22e from the left. In this case, the current flows in the same direction in both the second conductor pattern 2a and the second conductor pattern 2b, thus... Figure 5Compared to the original pattern, the inductance value of the second inductor L2 is increased. Similarly, the inductance value can be adjusted by adding a reverse pattern to the connection point.

[0081] Compared to filter device 100, the inductance of the third inductor L3 in filter device 200 is smaller. Therefore, the resonant frequency f0 of filter device 200 is higher than that of filter device 100. Figure 7 This is a graph showing the attenuation characteristics of the filter device 200 according to Embodiment 2. Figure 7 In the graph, the horizontal axis represents frequency, and the vertical axis represents attenuation characteristics, showing that the attenuation increases towards the bottom. The resonant frequency f0 of filter device 100 is approximately 4.85 GHz, while that of filter device 200 is approximately 5.05 GHz. Therefore, from... Figure 7 It can be seen that, compared with filter device 100, the inductance of the third inductor L3 is smaller, thus the resonant frequency f0 of filter device 200 is higher. Furthermore, the coupling coefficient k remains unchanged in both filter device 100 and filter device 200. Figure 7 The widths of the attenuation poles shown are also approximately the same. Furthermore, the resonant frequency f0 of filter device 200 is lower than the resonant frequency f0 of the filter device without the third inductor L3.

[0082] (Implementation Method 3)

[0083] In Embodiment 3, the structure of the filter device is described when an inductor with a larger inductance than the third inductor L3 described in Embodiment 1 is added.

[0084] [Filter Device Construction]

[0085] First, the filter device according to Embodiment 3 will be described with reference to the accompanying drawings. Figure 8 This is a perspective view of the filter device 300 according to Embodiment 3. Here, in Figure 8 In this design, the short side direction of the filter device 300 is defined as the X direction, the long side direction as the Y direction, and the height direction as the Z direction. Furthermore, in... Figure 8 In the filter device 300 shown, for the filter with Figure 1 The filter device 100 shown has the same structure and is labeled with the same reference numerals, and detailed descriptions are not repeated.

[0086] The filter device 300 is a cuboid-shaped chip component formed by stacking two inductors and one capacitor in the Z direction. For example... Figure 8As shown, the filter device 300 is composed of an insulator 3 formed by stacking multiple insulating substrates (insulator layers) on which a first conductor pattern of a first inductor L1, a second conductor pattern of a second inductor L2, and an electrode pattern of a capacitor C1 are formed. The structures of the first inductor L1 and the second inductor L2 of the filter device 300 are similar to those of the first inductor L1 and the second inductor L2. Figure 1 The filter device 100 shown is the same, but the structure of capacitor C1 is different.

[0087] In capacitor C1, multiple electrode patterns 5a~5c are stacked on the lower layer of the second inductor L2, separated by an insulating layer. The second conductor pattern 2d of the second inductor L2 (see reference) Figure 4 Electrode pattern 5a of capacitor C1 is electrically connected to the external electrode 4b via through-hole conductor 37. Electrode pattern 5b is not electrically connected to the external electrode 4b or other wiring patterns, and is a floating electrode. Electrode pattern 5c is electrically connected to the external electrode 4b on one side (first side) of the insulator 3 via wiring pattern 51c. In addition, electrode pattern 5c does not have through-hole conductor 41 for electrical connection to the external electrode 4b. That is, capacitor C1 has neither a path for current to flow from the external electrode 4b on one side (first side) to the external electrode 4b on the other side (second side) via electrode pattern 5c and wiring pattern 51c, nor a path for current to flow from the external electrode 4b on one side to the external electrode 4b on the bottom surface via through-hole conductor 41.

[0088] Therefore, in the filter device 300, a third inductor L3 is formed by a path from the wiring patterns 11b, 11d at one end of the first inductor L1, through the external electrode 4b on the side (first side) of the insulator 3, the external electrode 4b on the bottom surface, the external electrode 4b on the side (second side), and reaching the wiring pattern 21e at one end of the second inductor L2. Regarding the third inductor L3, since the inductor is formed by a path that bypasses the inner side of the insulator 3 and passes through the external electrode 4b on the outer side of the insulator 3, it is similar to... Figure 1 Compared to the case where the inductor is formed by a path passing through the inside of the insulator 3, the inductance is increased. Figure 8 The opening of the third inductor L3 shown is also formed on the XZ plane. Therefore, the magnetic coupling between the first inductor L1 and the third inductor L3 is weaker than the magnetic coupling between the first inductor L1 and the second inductor L2.

[0089] The second inductor L2, the third inductor L3, and the capacitor C1 are connected in series within the insulator 3 to form an LC series resonator. Therefore, the filter device 300 generates attenuation poles through the LC series resonator and has a resonant frequency.

[0090] [Exploded top view of the filter device]

[0091] Next, the structure of each layer is explained using exploded top views. Figure 9 This is an exploded top view showing the structure of the filter device 300 according to Embodiment 3. Furthermore, in Figure 9 In the middle, the filter device 300, apart from the structure of capacitor C1, is similar to... Figure 1 Except for the filter device 300 shown, the structure is the same, therefore in Figure 9 The exploded top view of the first inductor L1 and the second inductor L2 is omitted. The same reference numerals are used to label the same structures, and detailed descriptions are not repeated.

[0092] An electrode pattern 5c constituting another electrode of capacitor C1 is formed on the insulating substrate 3k. Viewed from the top side, the electrode pattern 5c is positioned opposite to the electrode pattern 5b. The electrode pattern 5c is connected to an external electrode 4b on one side (see reference 51c) via a wiring pattern 51c. Figure 8 Electrical connection. Therefore, electrode pattern 5c is not connected to the external electrode 4b on the other side (see reference). Figure 8 Electrical connection. Furthermore, preferably, as... Figure 9 As shown, the wiring pattern 51c also extends towards the external electrode 4b on the other side, which is not electrically connected. By providing this extended portion of the wiring pattern 51c, this portion can be used as part of the capacitance of the capacitor C1, and deviations in characteristics caused by the manufacturing of the capacitor C1 can be suppressed. On the insulating substrate 3k, when viewed from the top surface, a wiring pattern 52 is provided on the left side within the insulator 3. The wiring pattern 52 is electrically connected to the external electrodes 4a on the two opposing sides via the wiring pattern 52c. In addition, the wiring pattern 52 has a connection portion 38a that connects to the through-hole conductor 38.

[0093] Regarding capacitor C1, it is constructed using electrode patterns 5a, 5b, and 5c. Insulating substrates 31 to 3n are also provided below capacitor C1. Insulating substrate 31 has a wiring pattern 53 with a connection portion 38b connected to a through-hole conductor 38. Insulating substrate 3m has a wiring pattern 55 with a connection portion 38c connected to a through-hole conductor 38. Insulating substrate 3n has a connection portion 38d connected to a through-hole conductor 38. The through-hole conductor 38 is electrically connected to an external electrode 4a provided on the bottom surface via the connection portion 38d. Furthermore, in the filter device 300, there is no... Figure 1 Wiring patterns 54, 56, and through-hole conductors 39, 41 are provided in the filter device 100 shown.

[0094] Compared to filter device 100, the third inductor L3 of filter device 300 has a larger inductance. Therefore, the resonant frequency f0 of filter device 300 is lower than that of filter device 100. Figure 10 This is a graph showing the attenuation characteristics of the filter device 300 according to Embodiment 3. Figure 10 In the graph, the horizontal axis represents frequency, and the vertical axis represents attenuation characteristics, showing that the attenuation increases towards the bottom. The resonant frequency f0 of filter device 100 is approximately 4.85 GHz, while that of filter device 300 is approximately 4.50 GHz. Therefore, from... Figure 10 It can be seen that, compared with filter device 100, the inductance of the third inductor L3 is larger, thus the resonant frequency f0 of filter device 300 is higher. Furthermore, the coupling coefficient k remains unchanged in both filter device 100 and filter device 300. Figure 10 The widths of the various attenuation poles shown are also roughly the same.

[0095] [Variation Example]

[0096] (a) in Figure 2 The circuit diagram of the filter device 100 shown illustrates that the second path TL2 is a short-circuit path. However, by making the inductance of the second path TL2 smaller than the mutual inductance M between the first inductor L1 and the second inductor L2, the second path TL2 can be considered a short-circuit path. Therefore, it is preferable that the inductance of the second path TL2 is smaller than the mutual inductance M between the first inductor L1 and the second inductor L2.

[0097] (b) In the above embodiment, the relationship between the inductance of the first inductor L1 and the inductance of the second inductor L2 is not specifically stated, but it is preferable that the inductance of the first inductor L1 is smaller than the inductance of the second inductor L2. This reduces the overall loss of the filter device.

[0098] (c) In the above embodiment, it is explained that: the first inductor L1 is electrically connected to the external electrode 4b through first conductor patterns 1b and 1d, and the second inductor L2 is electrically connected to the external electrode 4b through a second conductor pattern 2a. However, the conductor patterns electrically connected to the external electrode 4b are not limited to the first conductor patterns 1b and 1d and the second conductor pattern 2a, and may be other conductor patterns. By changing the conductor patterns electrically connected to the external electrode 4b, the inductance of the third inductor L3 can be adjusted. For example, when the first inductor L1 is electrically connected to the external electrode 4b through first conductor patterns 1a and 1c located outside the first conductor patterns 1b and 1d, the path constituting the third inductor L3 becomes longer. Therefore, the inductance increases.

[0099] (d) In the above embodiments, there are no particular limitations on the positions where the first conductor patterns 1b and 1d are electrically connected to the external electrode 4b, and the positions where the second conductor pattern 2a is electrically connected to the external electrode 4b. However, the coupling coefficient k can be changed by moving the position of the connection in the Y-axis direction. For example, if the connection is located near the center of the insulator 3, the area of ​​the openings of the first inductor L1 and the second inductor L2 becomes smaller, thus reducing the coupling coefficient k. On the other hand, if the connection is located near the end of the insulator 3, the area of ​​the openings of the first inductor L1 and the second inductor L2 becomes larger, thus increasing the coupling coefficient k.

[0100] (e) In the above embodiments, such as Figure 2 As shown in (b), an antenna device 150 including a feed circuit RF1, a filter device 100, and a radiating element 155 is illustrated. However, the antenna device including the filter device 100 is not limited to... Figure 2 Antenna device 150 is shown in (b). For example, an antenna device including filter device 100 may also include matching circuitry. Figure 11 This is a circuit diagram of the antenna devices 150a and 150b involved in Modification Example 1. Furthermore, in Figure 11 In the antenna devices 150a and 150b shown, for the antennas... Figure 2 The antenna device 150 shown has the same structure and is labeled with the same reference numerals, and detailed descriptions are not repeated.

[0101] Figure 11 Antenna device 150a shown in (a) includes a feed circuit RF1, a filter device 100, a matching circuit 110, and a radiating element 155. The radiating element 155 is connected to the feed circuit RF1 via wiring 101, and the filter device 100 and the matching circuit 110 are connected in series with wiring 101. The matching circuit 110 is disposed between the feed circuit RF1 and the filter device 100. The matching circuit 110 is a circuit used for impedance matching with the radiating element 155, the feed circuit RF1, the filter device 100, etc., and is composed of resistors, inductors, capacitors, etc.

[0102] The matching circuit can also be set not only between the power supply circuit RF1 and the filter device 100, but also between the filter device 100 and the radiating element 155. Figure 11Antenna device 150b shown in (b) includes a feed circuit RF1, a filter device 100, matching circuits 110 and 120, and a radiating element 155. Matching circuit 120 is also provided between filter device 100 and radiating element 155. Matching circuit 120 is connected in series with wiring 101 and is used for impedance matching with radiating element 155, feed circuit RF1, filter device 100, etc. Matching circuit 120 is composed of resistors, inductors, capacitors, etc., but can be a circuit with the same structure as matching circuit 110 or a circuit with a different structure.

[0103] Furthermore, in antenna device 150b, a matching circuit 110 is provided between the feed circuit RF1 and the filter device 100, and a matching circuit 120 is provided between the filter device 100 and the radiating element 155; however, it may also be a structure that only provides the matching circuit 120. Furthermore, in Figure 11 Antenna device 150a shown in (a) and Figure 11 In the antenna device 150b shown in (b), it is illustrated that the matching circuits 110 and 120 are connected in series with the wiring 101, but at least one of the matching circuits 110 and 120 can also be connected in parallel (shunt connection) between the wiring 101 and ground (GND).

[0104] (f) In the above embodiments, such as Figure 2 As shown in (b), an antenna device 150 in which the filter device 100 is connected in series with the feed circuit RF1 and the radiating element 155 has been described. However, the antenna device including the filter device 100 is not limited to... Figure 2 Antenna device 150 is shown in (b). For example, it may also be an antenna device including filter device 100 connected in parallel with feed circuit RF1. Figure 12 This is the circuit diagram of antenna devices 150c and 150d involved in Modification Example 2. Furthermore, in Figure 12 In the antenna devices 150c and 150d shown, for the antennas... Figure 2 The antenna device 150 shown has the same structure and is labeled with the same reference numerals, and detailed descriptions are not repeated.

[0105] Figure 12 The antenna device 150c shown in (a) includes a feed circuit RF1, a filter device 100, and a radiating element 155. The radiating element 155 is connected to the feed circuit RF1 via wiring 101, and the filter device 100 is connected in parallel between wiring 101 and ground (GND). That is, the antenna device 150c includes a filter device 100 with terminal P1 (first terminal) connected to ground (GND) and terminal P2 (second terminal) connected to wiring 101.

[0106] In antenna device 150c, nothing is connected on wiring 102 that connects to filter device 100, but a matching circuit can still be connected. Figure 12 Antenna device 150d shown in (b) includes a feed circuit RF1, a filter device 100, matching circuits 110 and 120, and a radiating element 155. In antenna device 150d, matching circuits 110 and 120 are connected in series with wiring 102 connecting the filter device 100. Matching circuit 110 is connected between ground (GND) and the filter device 100, and matching circuit 120 is connected between the filter device 100 and wiring 101.

[0107] Matching circuits 110 and 120 are used for impedance matching with radiating element 155, power supply circuit RF1, filter device 100, etc. Matching circuits 110 and 120 are composed of resistors, inductors, capacitors, etc., but matching circuits 110 and 120 can be circuits with the same structure or circuits with different structures.

[0108] (g) In the above embodiments, such as Figure 2 As shown in (b), an antenna device 150 in which a filter device 100 is provided in the wiring 101 connecting the radiating element 155 to the feed circuit RF1 has been described. However, the antenna device including the filter device 100 is not limited to... Figure 2 Antenna device 150 shown in (b). For example, it may also be an antenna device in which a filter device 100 is provided at the short-circuit point of the radiating element. Figure 13 This is the circuit diagram of antenna devices 150e and 150f involved in Variation Example 3. Furthermore, in Figure 13 In the antenna devices 150e and 150f shown, for the antennas... Figure 2 The antenna device 150 shown has the same structure and is labeled with the same reference numerals, and detailed descriptions are not repeated.

[0109] Figure 13 Antenna device 150e shown in (a) includes a feed circuit RF1, a filter device 100, and a radiating element 155. The radiating element 155 is, for example, an inverted-F antenna with a short-circuit point P3. The short-circuit point P3 is connected to ground (GND) via wiring 103. The filter device 100 is not located on wiring 101 connecting the radiating element 155 to the feed circuit RF1, but rather on wiring 103. That is, antenna device 150e includes a filter device 100 connected in parallel with the feed circuit RF1. In other words, antenna device 150e includes a filter device 100 with terminal P1 (first terminal) connected to ground (GND) and terminal P2 (second terminal) connected to the short-circuit point P3.

[0110] In antenna device 150e, nothing is connected on wiring 103 that connects to filter device 100, but a matching circuit can be connected. Figure 13 Antenna device 150f shown in (b) includes a feed circuit RF1, a filter device 100, matching circuits 110 and 120, and a radiating element 155. In antenna device 150f, matching circuits 110 and 120 are connected in series with wiring 103 connecting the filter device 100. Matching circuit 110 is connected between ground (GND) and the filter device 100, and matching circuit 120 is connected between the filter device 100 and the short-circuit point P3 of the radiating element 155.

[0111] Matching circuits 110 and 120 are used for impedance matching with radiating element 155, power supply circuit RF1, filter device 100, etc. Matching circuits 110 and 120 are composed of resistors, inductors, capacitors, etc., but matching circuits 110 and 120 can be circuits with the same structure or circuits with different structures.

[0112] [Way]

[0113] (1) The filter device involved in this disclosure is a filter device with an attenuation frequency band, comprising: a first terminal; a second terminal; a first inductor connected to the first terminal; and a series resonator disposed in the first path of a first path and a second path arranged in parallel between the first inductor and the second terminal, the series resonator comprising: a second inductor; a capacitor connected in series with the second inductor; and a third inductor connected in series with the second inductor and the capacitor, wherein the magnetic coupling between the first inductor and the third inductor is weaker than the magnetic coupling between the first inductor and the second inductor.

[0114] Therefore, the filter device disclosed herein, by incorporating a third inductor with weak magnetic coupling, can achieve a filter device with a steep attenuation pole in the low frequency band.

[0115] (2) In the filter device described in (1), the inductance of the second path is less than the mutual inductance between the first inductor and the second inductor.

[0116] (3) In the filter device described in (1) or (2), the inductance of the first inductor is less than the inductance obtained by adding the inductance of the second inductor and the inductance of the third inductor.

[0117] (4) In any of (1) to (3) the filter device, the first inductor, the second inductor, the third inductor and the capacitor are disposed in an insulator having a pair of main surfaces facing each other and four sides connecting the main surfaces, the insulator comprising: a first external electrode constituting the first terminal; and a second external electrode constituting the second terminal, the third inductor being disposed using a portion of the second external electrode.

[0118] (5) In the filter device described in (4), when viewed from the side of one of the main surfaces, the opening surface of the third inductor forming the coil is orthogonally arranged to the opening surface of the first inductor forming the coil.

[0119] (6) In the filter device described in (4) or (5), the second external electrode is at least disposed on a first side and a second side facing the first side, one end of the first inductor is electrically connected to the second external electrode disposed on the first side, one end of the second inductor is electrically connected to the second external electrode disposed on the second side, the other end of the second inductor is electrically connected to the first electrode of the capacitor, the second electrode of the capacitor faces the first electrode and is electrically connected to the first side and the second side of the second external electrode, and the third inductor is formed by a path from one end of the first inductor through the second external electrode of the first side, the second electrode of the capacitor, the second external electrode of the second side and reaching one end of the second inductor.

[0120] (7) In the filter device described in (6), the path constituting the third inductor is single.

[0121] (8) In the filter device described in (4) or (5), the second external electrode is at least disposed on a first side, a second side facing the first side, and a first main surface that is one of the main surfaces, one end of the first inductor is electrically connected to the second external electrode disposed on the first side, one end of the second inductor is electrically connected to the second external electrode disposed on the first side, and the third inductor is formed by a path from one end of the first inductor through the second external electrode on the first side to one end of the second inductor.

[0122] (9) In the filter device described in (4) or (5), the second external electrode is at least disposed on a first side, a second side facing the first side, and a first main surface that is one of the main surfaces. One end of the first inductor is electrically connected to the second external electrode disposed on the first side, and one end of the second inductor is electrically connected to the second external electrode disposed on the second side. The third inductor is formed by a path that starts from one end of the first inductor, passes through the second external electrode on the first side, the second external electrode on the first main surface, the second external electrode on the second side, and reaches one end of the second inductor.

[0123] (10) The antenna device involved in this disclosure is an antenna device capable of radiating radio waves, comprising: a radiating element; a feeding circuit that provides a high-frequency signal to the radiating element; and a filter device according to any one of (1) to (9), which is connected in series between the radiating element and the feeding circuit.

[0124] (11) The antenna device involved in this disclosure is an antenna device capable of radiating radio waves, comprising: a radiating element; a feeding circuit that provides a high-frequency signal to the radiating element; and a filter device according to any one of (1) to (9), comprising a first terminal and a second terminal, the first terminal being connected to ground, and the second terminal being connected to a wiring that connects the feeding circuit to the radiating element, or to a short-circuit point of the radiating element.

[0125] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is set forth in the claims rather than in the foregoing description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0126] Explanation of reference numerals in the attached figures

[0127] 1a~1d: First conductor pattern; 2a~2d: Second conductor pattern; 3: Insulator; 3a~3n: Insulating substrate; 4a, 4b: External electrodes; 5a~5c: Electrode patterns; 100~300: Filter device; 110, 120: Matching circuit; 150, 150a~150f: Antenna device; 155: Radiation element; C1: Capacitor; L1: First inductor; L2: Second inductor; L3: Third inductor; RF1: Feed circuit; RS: Series resonator; TL1: First path; TL2: Second path.

Claims

1. A filter device having an attenuation band, the filter device comprising: a first terminal; a second terminal; a first inductor connected to the first terminal; and a series resonator disposed in the first path of a first path and a second path connected in parallel between the first inductor and the second terminal, the series resonator comprising: Second inductor; A capacitor, which is connected in series with the second inductor; And a third inductor, which is connected in series with the second inductor and the capacitor, wherein the magnetic coupling between the first inductor and the third inductor is weaker than the magnetic coupling between the first inductor and the second inductor.

2. The filter device according to claim 1, wherein, The inductance of the second path is less than the mutual inductance between the first inductor and the second inductor.

3. The filter device according to claim 1 or 2, wherein, The inductance of the first inductor is less than the inductance obtained by adding the inductances of the second inductor and the third inductor.

4. The filter device according to any one of claims 1 to 3, wherein, The first inductor, the second inductor, the third inductor, and the capacitor are disposed in an insulator having a pair of main surfaces facing each other and four side surfaces connecting the main surfaces. The insulator includes a first external electrode forming the first terminal and a second external electrode forming the second terminal. The third inductor is disposed using a portion of the second external electrode.

5. The filter device according to claim 4, wherein, When viewed from one of the main surfaces, the opening surface of the third inductor forming the coil is orthogonally arranged to the opening surface of the first inductor forming the coil.

6. The filter device according to claim 4 or 5, wherein, The second external electrode is disposed at least on a first side and a second side facing the first side. One end of the first inductor is electrically connected to the second external electrode disposed on the first side, and one end of the second inductor is electrically connected to the second external electrode disposed on the second side. The other end of the second inductor is electrically connected to the first electrode of the capacitor. The second electrode of the capacitor faces the first electrode and is electrically connected to the first side and the second side of the second external electrode. The third inductor is formed by a path starting from one end of the first inductor, passing through the second external electrode on the first side, the second electrode of the capacitor, the second external electrode on the second side, and reaching one end of the second inductor.

7. The filter device according to claim 6, wherein, The path that constitutes the third inductor is single.

8. The filter device according to claim 4 or 5, wherein, The second external electrode is disposed at least on the first side, the second side facing the first side, and the first main surface, which is one of the main surfaces. One end of the first inductor is electrically connected to the second external electrode disposed on the first side, and one end of the second inductor is electrically connected to the second external electrode disposed on the first side. The third inductor is formed by a path that starts from one end of the first inductor, passes through the second external electrode on the first side, and reaches one end of the second inductor.

9. The filter device according to claim 4 or 5, wherein, The second external electrode is disposed at least on the first side, the second side facing the first side, and the first main surface, which is one of the main surfaces. One end of the first inductor is electrically connected to the second external electrode disposed on the first side, and one end of the second inductor is electrically connected to the second external electrode disposed on the second side. The third inductor is formed by a path starting from one end of the first inductor, passing through the second external electrode on the first side, the second external electrode on the first main surface, the second external electrode on the second side, and reaching one end of the second inductor.

10. An antenna device capable of radiating radio waves, the antenna device comprising: a radiating element; a feeding circuit that provides a high-frequency signal to the radiating element; and a filter device according to any one of claims 1 to 9, which is connected in series between the radiating element and the feeding circuit.

11. An antenna device capable of radiating radio waves, the antenna device comprising: a radiating element; a feeding circuit that provides a high-frequency signal to the radiating element; and a filter device according to any one of claims 1 to 9, comprising a first terminal and a second terminal, the first terminal being connected to ground, and the second terminal being connected to a wiring connecting the feeding circuit to the radiating element, or to a short-circuit point of the radiating element.

Images