Filter device, and high-frequency front-end circuit and diplexer incorporating same

Abstract

This filter device (100) comprises: a main body (110); and an inductor (L11), an inductor (L12), and an inductor (L13) which are provided to the main body (110), wherein a signal is transmitted from an antenna terminal (TA) to a first terminal (T1). The inductor (L11) is connected to the antenna terminal (TA), and the inductor (L!2) is connected to the first terminal (T1). The inductor (L13) is connected to a signal transmission path between the inductor (L11) and the inductor (L12). When viewed in a plan view in the direction of a normal line of the main body (110), the inductor (L11) and the inductor (L12) are provided to be adjacent to each other.

Description

[Technical field]

[0001] The present disclosure relates to a filter device, and a high-frequency front-end circuit and a diplexer incorporating the same, and more particularly to a technique for adjusting the pass characteristics of a filter device. [Background technology]

[0002] Japanese Patent No. 3702767 (Patent Document 1) discloses an LC filter circuit in which a parallel resonant trap circuit is connected in series between an LC parallel resonator and an input terminal and / or an output terminal. In the LC filter circuit disclosed in Japanese Patent No. 3702767 (Patent Document 1), the parallel resonant trap circuit generates an attenuation pole near the center frequency of the pass band, so that the amount of attenuation required for a desired frequency can be ensured. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3702767 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, so-called multiband communication, which uses high-frequency signals in multiple frequency bands for communication, has been promoted in communication standards such as Wi-Fi and the fifth generation mobile communication system (5G). In multiband communication, it is necessary to secure the frequency bandwidth in the specified passband, and to secure the attenuation amount in the non-passband to avoid interference with adjacent frequency bands.

[0005] In order to selectively pass high-frequency signals in a desired passband, a filter device such as that described in Japanese Patent No. 3702767 (Patent Document 1) is used. Here, known methods for adjusting the frequency bandwidth include using multiple LC resonators or adding inductors or the like to strengthen the coupling between the resonators. However, the above-mentioned method of adjustment using additional elements may increase the cost or the size of the device as the number of parts increases.

[0006] The present disclosure has been made to solve such problems, and has as its object to expand the adjustment margin of the passband width with a relatively simple configuration in a filter device including a plurality of inductors. [Means for solving the problem]

[0007] The filter device according to the present disclosure includes a main body in which a plurality of dielectric layers are laminated, and a first inductor, a second inductor, and a third inductor disposed on the main body, and transmits a signal from an input terminal to an output terminal. The first inductor is connected to the input terminal, and the second inductor is connected to the output terminal. The third inductor is connected to a signal transmission path between the first inductor and the second inductor. When viewed in a plan view from the normal direction of the main body, the first inductor and the second inductor are disposed adjacent to each other. Effect of the Invention

[0008] According to the filter device of the present disclosure, the input side inductor (first inductor) is arranged adjacent to the output side inductor (second inductor) in the dielectric body. With this configuration, the adjustment margin of the strength of the magnetic coupling between the first inductor and the second inductor is larger than when the first inductor and the second inductor are arranged with the third inductor in between. This increases the adjustment margin of the passband width of the filter device without adding a new element. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram of a communication device having a high-frequency front-end circuit to which a filter device according to a first embodiment is applied. [Diagram 2] 2 is an equivalent circuit diagram of the filter device according to the first embodiment. [Diagram 3] FIG. 3 is a perspective view showing the inside of the filter device of FIG. 2. [Figure 4] 3 is an exploded perspective view showing an example of a layered structure of the filter device of FIG. 2. FIG. [Diagram 5] 3 is a diagram for explaining the arrangement of inductors in the filter device of FIG. 2. FIG. [Figure 6] 10A and 10B are diagrams for explaining the arrangement of inductors of a high-pass filter in a filter device of a comparative example. [Figure 7] 5 is a diagram showing a pass characteristic in the filter device of the first embodiment. FIG. [Figure 8] FIG. 11 is a perspective view showing the inside of a filter device according to a modified example. [Figure 9] FIG. 11 is a perspective view showing the inside of a filter device according to a second embodiment. [Figure 10] 10 is an equivalent circuit diagram of the filter device of FIG. 9. [Figure 11] 13 is a diagram for explaining an arrangement of inductors in a filter device according to a third embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0011] [Embodiment 1] (Basic configuration of communication device) 1 is a block diagram of a communication device 10 including a high-frequency front-end circuit 20 to which a filter device 100 according to an embodiment is applied. The high-frequency front-end circuit 20 splits a high-frequency signal received by an antenna device ANT into a plurality of predetermined frequency bands and transmits the split signals to a subsequent processing circuit. The high-frequency front-end circuit 20 is used in communication devices such as mobile terminals such as mobile phones, smartphones, and tablets, and personal computers equipped with communication functions.

[0012] 1, a communication device 10 includes a high-frequency front-end circuit 20 including a filter device 100, and an RF signal processing circuit (hereinafter, also referred to as "RFIC") 30. The high-frequency front-end circuit 20 shown in Fig. 1 is a receiving system front-end circuit. The high-frequency front-end circuit 20 includes the filter device 100 and amplifier circuits LNA1 and LNA2.

[0013] The filter device 100 is a diplexer including a filter FLT1 (first filter) and a filter FLT2 (second filter) having passbands in different frequency ranges. In the following description, the filter device 100 may be referred to as a "diplexer."

[0014] The filter FLT1 is connected between the antenna terminal TA, which is a common terminal, and the first terminal T1. The filter FLT1 is a high-pass filter whose pass band is the frequency range of the high band (HB) group and whose non-pass band is the frequency range of the low band (LB) group. The filter FLT2 is connected between the antenna terminal TA and the second terminal T2. The filter FLT2 is a low-pass filter whose pass band is the frequency range of the low band group and whose non-pass band is the frequency range of the high band group. The filters FLT1 and FLT2 may be band-pass filters. The pass band of the filter FLT1 corresponds to the "first frequency band" of the present disclosure, and the pass band of the filter FLT2 corresponds to the "second frequency band" of the present disclosure.

[0015] Each of the filters FLT1 and FLT2 passes only high-frequency signals that correspond to the pass band of the respective filter among the high-frequency signals received by the antenna device ANT, thereby splitting the received signal from the antenna device ANT into signals of a plurality of predetermined frequency bands.

[0016] Each of the amplifier circuits LNA1 and LNA2 is a so-called low noise amplifier. The amplifier circuits LNA1 and LNA2 amplify the high frequency signal that has passed through the corresponding filter with low noise and transmit the amplified signal to the RFIC 30.

[0017] The RFIC 30 is an RF signal processing circuit that processes radio frequency signals transmitted and received by the antenna device ANT. Specifically, the RFIC 30 processes radio frequency signals input from the antenna device ANT via a receiving side signal path of the radio frequency front-end circuit 20 by down-conversion or the like, and outputs the received signal generated by the signal processing to a baseband signal processing circuit (not shown).

[0018] 1, when the high-frequency front-end circuit 20 is used as a receiving circuit, in the filter device 100, the antenna terminal TA becomes the input terminal IN, and the first terminal T1 and the second terminal T2 become the first output terminal OUT1 and the second output terminal OUT2, respectively. 20 can also be used as a transmission circuit. In this case, the first terminal T1 and the second terminal T2 of the filter device 100 each serve as an input terminal, and the antenna terminal TA serves as a common output terminal. In that case, a power amplifier is used as the amplifier included in the amplification circuit.

[0019] (Configuration of filter device) Fig. 2 is a diagram showing an equivalent circuit of one example of the filter device (diplexer) 100 in Fig. 1. As described in Fig. 1, the filter FLT1 is connected between the antenna terminal TA and the first terminal T1. Moreover, the filter FLT2 is connected between the antenna terminal TA and the second terminal T2. An inductor L1 is commonly connected between the filters FLT1, FLT2 and the antenna terminal TA. The inductor L1 is used to adjust the impedance between the antenna device ANT and the filter device 100.

[0020] The filter FLT1 includes inductors L11, L12 and a capacitor C11 that form a series arm circuit, and an inductor L13 and capacitors C12, C13 that form a parallel arm circuit. The inductor L11 is connected to the inductor L1, and the inductor L12 is connected to the first terminal T1. The capacitor C11 is connected between the inductor L11 and the inductor L12.

[0021] One end of the capacitor C12 is connected to the connection node between the inductor L11 and the capacitor C11. The other end of the capacitor C12 is connected to the ground terminal GND via the inductor L13. One end of the capacitor C13 is connected to the connection node between the inductor L12 and the capacitor C11. The other end of the capacitor C13 is connected to the ground terminal GND via the inductor L13.

[0022] The filter FLT1 functions as a bandpass filter due to a resonator formed of the inductor L13 and the capacitors C12, C13 and C11 in the parallel arm circuit, and the inductors L11 and L12 functioning as trap inductors.

[0023] The filter FLT2 includes inductors L21, L22 and a capacitor C21 that form a series arm circuit, and a capacitor C22 that forms a parallel arm circuit. One end of the inductor L21 is connected to the inductor L1, and the other end is connected to the second terminal T2 via the inductor L22. The capacitor C21 is connected in parallel to the inductor L22. One end of the capacitor C22 is connected to a connection node between the inductor L21 and the inductor L22. The other end of the capacitor C22 is connected to the ground terminal GND.

[0024] In the example of the filter device 100 according to the first embodiment, the passband of the filter FLT1 is set to about 2.4 to 10 GHz, and the passband of the filter FLT2 is set to about 0 to 1.6 GHz. Therefore, in the filter device 100, the filter FLT1 functions as a high-pass filter.

[0025] Next, the internal configuration of the filter device 100 will be described in detail with reference to Fig. 3 to Fig. 5. Fig. 3 is a perspective view showing the inside of the filter device 100 of Fig. 2, and Fig. 4 is an exploded perspective view showing an example of a layered structure of the filter device 100. Fig. 5 is a diagram for explaining the arrangement of inductors in the filter device 100, and specifically, a plan view of the dielectric layers in Fig. 4.

[0026] 3 and 4, the filter device 100 includes a rectangular or substantially rectangular parallelepiped main body 110 formed by stacking a plurality of dielectric layers LY1 to LY11 in a predetermined direction. 11The direction in which the layers are stacked is defined as the lamination direction. Each dielectric layer of the main body 110 is formed of ceramics such as low temperature co-fired ceramics (LTCC) or resin. Inside the main body 110, a plurality of electrodes provided on each dielectric layer and a plurality of vias provided between the dielectric layers form inductors and capacitors for configuring the filters FLT1 and FLT2. Note that in Figs. 3 to 5, the dielectric of the main body 110 is omitted, and only the wiring patterns, vias, and terminal conductors provided inside are shown. In this specification, the term "via" refers to a conductor formed in a dielectric layer to connect electrodes provided on different dielectric layers. The vias are formed, for example, by conductive paste, plating, and / or metal pins.

[0027] In the following description, the stacking direction of main body 110 is referred to as the "Z-axis direction", the direction perpendicular to the Z-axis direction and along the long side of main body 110 is referred to as the "X-axis direction", and the direction along the short side of main body 110 is referred to as the "Y-axis direction". In addition, hereinafter, the positive direction of the Z axis in each drawing may be referred to as the upper side, and the negative direction as the lower side.

[0028] A directionality mark DM for specifying the direction of the filter device 100 is arranged on an upper surface 111 (dielectric layer LY1) of the main body 110. An antenna terminal TA, a first terminal T1, a second terminal T2, and a ground terminal GND, which are external terminals for connecting the filter device 100 to an external device, are arranged on a lower surface 112 (dielectric layer LY11) of the main body 110. Each external terminal is a flat electrode, and is an LGA (Land Grid Array) terminal regularly arranged on the lower surface 112 of the main body 110. In the example shown in FIG. 3 and FIG. 4, roughly speaking, a high-band filter FLT1 is arranged on the right side (positive direction of the X-axis) of the main body 110, and a low-band filter FLT2 is arranged on the left side (negative direction of the X-axis).

[0029] An inductor L1, which is a common element, is configured from the antenna terminal TA arranged on the lower surface 112 (dielectric layer LY11) to the branch point PB1 of the dielectric layer LY2 by the vias V1 and V1A and the plate electrode P1. As described in FIG. 2, the inductor L11 of the filter FLT1 and the inductor L21 of the filter FLT2 are connected to the branch point PB1.

[0030] First, the details of the filter FLT1, which is a high-pass filter, will be described. A linear plate electrode PL1 extending from the branch point PB1 in the positive direction of the X-axis is connected to the branch point PB1. A via VL1 is connected to an end of the plate electrode PL1. The plate electrode PL1 is connected to one end of a plate electrode PL1A provided on the dielectric layer LY8 through the via VL1. The plate electrode PL1A is a strip-shaped electrode having a substantially J-shape. A via VL1A is connected to the other end of the plate electrode PL1A, and the plate electrode PL1A is connected to a flat capacitor electrode PC1 provided on the dielectric layer LY6 through the via VL1A. The inductor L11 in FIG. 2 is formed by the path of the plate electrode PL1, the via VL1, the plate electrode PL1A, and the via VL1A.

[0031] A part of the capacitor electrode PC1 overlaps with a flat-plate-shaped capacitor electrode PC2 provided on the dielectric layer LY5 when the main body 110 is viewed in a plan view from the normal direction. Another part of the capacitor electrode PC1 overlaps with a flat-plate-shaped capacitor electrode PC3 provided on the dielectric layer LY4. The capacitor electrode PC3 is disposed so as to overlap with the capacitor electrode PC2 as well.

[0032] The capacitor electrodes PC1 and PC2 form a capacitor C11 in Fig. 2. The capacitor electrodes PC1 and PC3 form a capacitor C12 in Fig. 2. The capacitor electrodes PC2 and PC3 form a capacitor C13 in Fig. 2.

[0033] The capacitor electrode PC2 is connected by a via VL2 to one end of a band-shaped plate electrode PL2 provided on the dielectric layer LY2. A via VL2A is connected to the other end of the plate electrode PL2. The plate electrode PL2 is connected by the via VL2A to one end of a band-shaped plate electrode PL2A provided on the dielectric layer LY10. The plate electrode PL2A has a substantially L-shape, and is connected to the first terminal T1 of the dielectric layer LY11 by a via V2 connected to the other end. The inductor L12 in FIG. 2 is formed by the path of the via VL2, the plate electrode PL2, the via VL2A, the plate electrode PL2A, and the via V2.

[0034] The capacitor electrode PC3 is connected by a via VL3 to one end of a band-shaped plate electrode PL3 provided on the dielectric layer LY2. A via VL3A is connected to the other end of the plate electrode PL3. The plate electrode PL3 is connected by the via VL3A to one end of a band-shaped plate electrode PL3A provided on the dielectric layer LY8. The plate electrode PL3A is a linear electrode extending in the X-axis direction, and is connected by a via VL3B connected to the other end to one end of a band-shaped plate electrode PL3B provided on the dielectric layer LY3.

[0035] The plate electrode PL3B is connected to one end of a band-shaped plate electrode PL3C provided on the dielectric layer LY8 by a via VL3C connected to the other end. The plate electrode PL3C is a linear electrode extending in the X-axis direction, and is connected to one end of a band-shaped plate electrode PL3D provided on the dielectric layer LY2 by a via VL3D connected to the other end. The plate electrode PL3D is a linear electrode extending in the X-axis direction, and is connected to a plate electrode PG provided on the dielectric layer LY10 by a via VL3E connected to the other end. The plate electrode PG is connected to a ground terminal GND provided on the dielectric layer LY11 by vias VG1 and VG2.

[0036] The inductor in FIG. 2 is formed by a path consisting of vias VL3 to VL3E, VG1, and VG2, and plate electrodes PL3 to PL3D and PG. L13In the example of the filter device 100 according to the first embodiment, the inductors L11, L12, and L13 forming the filter FLT1 are configured as vertical helical coils with the winding axis in the Y-axis direction.

[0037] Next, the details of the filter FLT2, which is a low-pass filter, will be described. A linear plate electrode PL4 extending from the branch point PB1 in the negative direction of the X-axis is connected to the branch point PB1. A via VL4 is connected to an end of the plate electrode PL4. The plate electrode PL4 is connected to one end of a plate electrode PL4A provided on the dielectric layer LY8 through the via VL4. The plate electrode PL4A is a linear electrode extending in the X-axis direction, and is connected to a plate electrode PL4B provided on the dielectric layer LY3 by the via VL4A connected to the other end. The via VL4A is slightly offset in the Y-axis direction on the dielectric layer LY4.

[0038] The plate electrode PL4B is a linear electrode extending in the X-axis direction, and is connected to one end of a band-shaped plate electrode PL4C provided on the dielectric layer LY7 by a via VL4B connected to the other end. A via VL4C is connected to the other end of the plate electrode PL4C. The plate electrode PL4C is connected to a plate electrode PL4D provided on the dielectric layer LY2 by the via VL4C. The plate electrode PL4D is a linear electrode extending in the X-axis direction, and is connected to one end of a band-shaped plate electrode PL4E provided on the dielectric layer LY8 by a via VL4D connected to the other end.

[0039] A via VL4E is connected to the other end of the plate electrode PL4E. The plate electrode PL4E is connected by the via VL4E to one end of a strip-shaped plate electrode PL4F provided on the dielectric layer LY3. The other end of the plate electrode PL4F is connected to a via VL4F. The plate electrode PL4F is connected by the via VL4F to a capacitor electrode PC4 provided on the dielectric layer LY9.

[0040] The path formed by the plate electrodes PL4-PL4F and the vias VL4-VL4F constitutes the inductor L21 in Fig. 2. Like each inductor of the filter FLT1, the inductor L21 is a vertical helical coil whose winding axis is in the Y-axis direction.

[0041] When the main body 110 is viewed in a plan view from the normal direction, a portion of the capacitor electrode PC4 overlaps with the plate electrode PG provided on the dielectric layer LY10. As described above, the plate electrode PG is connected to the ground terminal GND by the vias VG1 and VG2. Therefore, the capacitor electrode PC4 and the plate electrode PG form the capacitor C22 in FIG. 2.

[0042] In addition, another part of the capacitor electrode PC4 overlaps with the plate electrode P2 provided on the dielectric layer LY10 when viewed in a plan view from the normal direction of the main body 110. The plate electrode P2 is connected to the second terminal T2 of the dielectric layer LY11 by a via V3. Therefore, the capacitor electrode PC4 and the plate electrode P2 form the capacitor C21 in FIG.

[0043] The capacitor electrode PC4 is connected by a via VL5 to one end of a strip-shaped plate electrode PL5 provided on the dielectric layer LY2. A via VL5A is connected to the other end of the plate electrode PL5. The via VL5A connects the plate electrode PL5 to one end of a strip-shaped plate electrode PL5A provided on the dielectric layer LY3. A via VL5B is connected to the other end of the plate electrode PL5A. The via VL5B connects the plate electrode PL5A to a plate electrode P2 provided on the dielectric layer LY10.

[0044] 2 is configured by the vias VL5-VL5B and the plate electrodes PL5, PL5A. Each of the plate electrodes PL5, PL5A has a planar coil shape wound around the normal direction (Z-axis direction) of the main body 110. Therefore, the plate electrodes PL5, PL5A are configured as a planar coil with the Z-axis direction as the winding axis.

[0045] As described above, Fig. 5 is a plan view of the dielectric layer LY2 in the filter device 100. As described in Fig. 3 and Fig. 4, in the filter device 100, the filter FLT1, which is a high-pass filter, is configured on the lower side (positive direction of the X-axis) of Fig. 5 in the main body 110, and the filter FLT2, which is a low-pass filter, is configured on the upper side (negative direction of the X-axis) of Fig. 5.

[0046] The inductors in the filter FLT1 are arranged in the order of inductors L11, L13, and L12 along a signal transmission path from the antenna terminal TA on the input side toward the first terminal T1 on the output side on the equivalent circuit shown in Fig. 2. However, the actual arrangement of the inductors in the main body 110 is such that the inductors are arranged in the order of inductors L11, L12, and L13 from the long side 113 on the left side (negative direction of the Y axis) of the main body 110 toward the long side 114 on the right side (positive direction of the Y axis) of the main body 110.

[0047] In a conventional filter device, as shown in a filter device 100X of a comparative example in Fig. 6, in an actual main body, a plurality of inductors forming an LC filter are generally arranged in the same order as in the equivalent circuit from the input terminal (antenna terminal TA) toward the output terminal (first terminal T1). That is, an inductor L13 is arranged between an inductor L11 connected to the input terminal and an inductor L12 connected to the output terminal. In this case, the distance between the inductor L11 and the inductor L12 is long, and since the inductor L13 is sandwiched between them, the degree of magnetic coupling between the inductor L11 and the inductor L12 is relatively weak.

[0048] The inventors have discovered that in a bandpass filter forming the filter FLT1 as described above, the passband width of the bandpass filter can be adjusted by changing the degree of magnetic coupling between the input-side trap inductor and the output-side trap inductor.

[0049] 6, since the inductor L13 is disposed between the inductors L11 and L12, there is a limit to how close the inductors L11 and L12 can be brought, and the adjustment margin is small. Furthermore, when adjusting the distance between the inductors L11 and L12, the position of the inductor L13 must also be changed, and the degree of coupling between the inductors L11 and L13 and between the inductors L12 and L13 also changes at the same time, which may affect other filter characteristics.

[0050] In contrast, in the filter FLT1 in the filter device 100 of the first embodiment, the inductor L11 on the input side and the inductor L12 on the output side are disposed adjacent to each other in the main body 110, so that the distance between the inductors L11 and L12 is shortened and magnetic coupling is facilitated, compared with the configuration in which the inductors L11 and L12 are disposed at both ends of the main body as in the filter device 100X of the comparative example. Therefore, by adjusting the winding direction and / or the number of turns of each inductor, the adjustment margin of the magnetic coupling between the inductors L11 and L12 is increased. In addition, since it is not necessary to change the arrangement of the inductor L13 when adjusting the degree of coupling between the inductors L11 and L12, the influence on other filter characteristics is also reduced. Therefore, in the filter device 100 of the first embodiment, the adjustment margin of the passband width of the filter device is expanded by a relatively simple configuration without adding a new element.

[0051] (passage characteristics) Fig. 7 is a diagram showing the pass characteristic of the filter FLT1 in the filter device 100 of the embodiment 1. In Fig. 7, the horizontal axis represents frequency, and the vertical axis represents the insertion loss of the filter FLT1.

[0052] In FIG. 7, the winding direction of the inductor L11 and the inductor L12 is Reverse direction (That is, the direction of the generated magnetic field is reverse ) ofIn this case, the insertion loss when inductor L12 is placed at a specific reference distance from inductor L11 is shown by a solid line LN1, the insertion loss when inductor L12 is brought closer to inductor L11 than the reference distance is shown by a dashed line LN2, and the insertion loss when inductor L12 is moved farther from inductor L11 than the reference distance is shown by a dotted line LN3.

[0053] As shown in Figure 7, when the winding directions of the two inductors are opposite, moving the inductors closer to each other (i.e., weakening the degree of magnetic coupling) causes the position of the attenuation pole on the higher frequency side than the pass band to move toward the lower frequency side, narrowing the pass bandwidth. Conversely, moving the inductors farther apart (i.e., strengthening the degree of magnetic coupling) causes the position of the attenuation pole on the higher frequency side than the pass band to move toward the higher frequency side, widening the pass bandwidth. Note that there is no significant change in the attenuation amount and attenuation steepness in the non-pass band even if the distance between inductors L11 and L12 is changed.

[0054] Therefore, by arranging the inductor connected to the input terminal and the inductor connected to the output terminal adjacent to each other within the main body, as in the case of the filter FLT1 in the filter device 100, it is possible to increase the adjustment range of the passband width while reducing the effect on other filter characteristics.

[0055] When the winding directions of the two inductors are the same, moving the inductors closer to each other strengthens the degree of magnetic coupling, and the position of the attenuation pole on the higher frequency side than the passband moves to the higher frequency side. Conversely, moving the inductors farther apart weakens the degree of magnetic coupling, and the position of the attenuation pole on the higher frequency side than the passband moves to the lower frequency side.

[0056] (Modification) In the above-described first embodiment, the inductors forming the filter FLT1 are configured as inductors whose winding axes lie in the Y-axis direction. However, each of these inductors may be configured as an inductor whose winding axis lies in the Z-axis direction, like inductor L22 of filter FLT2.

[0057] Fig. 8 is a perspective view showing the inside of a modified filter device 100A. In the filter device 100A, an inductor L13 connected to a ground terminal GND includes a planar coil whose winding axis is in the Z-axis direction. Note that in Fig. 8, the description of elements that overlap with Figs. 3 and 4 will not be repeated.

[0058] 8, the via VL3 connected to the capacitor electrode PC3 of the dielectric layer LY4 is connected to one end of a band-shaped plate electrode PL3X provided on the dielectric layer LY2. The plate electrode PL3X has a substantially U-shape, and the other end is connected by the via VL3X to one end of a band-shaped plate electrode PL3Y provided on the dielectric layer LY3. The other end of the plate electrode PL3Y is connected by the via VL3Y to the plate electrode PG of the dielectric layer LY10, and is connected to the ground terminal GND through vias VG1 and VG2.

[0059] In this way, even if the inductor includes a planar coil whose winding axis is in the Z-axis direction, by arranging the inductor connected to the input terminal and the inductor connected to the output terminal adjacent to each other within the main body, it is possible to increase the adjustment range of the passband width while reducing the impact on other filter characteristics.

[0060] In the above filter device 100A, an example has been described in which the inductor L13 includes a planar coil whose winding axis is in the Z-axis direction, but the inductor L11 and / or the inductor L12 may include a planar coil whose winding axis is in the Z-axis direction. That is, at least one of the inductors forming the filter FLT1 may include a planar coil whose winding axis is in the Z-axis direction.

[0061] In addition, "inductor L11", "inductor L12", and "inductor L13" in the first embodiment correspond to the "first inductor", "second inductor", and "third inductor" in this disclosure, respectively. "Capacitor C11", "capacitor C12", and "capacitor C13" in the first embodiment correspond to the "first capacitor", "second capacitor", and "third capacitor" in this disclosure, respectively.

[0062] [Embodiment 2] In the first embodiment and the modified example, the filter device is a diplexer. However, the features of the present disclosure are also applicable to a filter device including a single filter.

[0063] Fig. 9 is a perspective view showing the inside of the filter device 200 of the second embodiment. Also, Fig. 10 is an equivalent circuit diagram of the filter device 200. The filter device 200 is a band-pass filter constituted by only the filter FLT1 in the filter device 100 of the first embodiment.

[0064] 9 and 10, in filter device 200, inductor L11A is connected to antenna terminal TA instead of inductor L11. In filter device 100 of the first embodiment, vias V1, V1A and plate electrode P1 from antenna terminal TA to branch point PB1 function as inductor L1, which is a common line for filters FLT1, FLT2. However, since filter device 200 is a single bandpass filter, in an equivalent circuit, a configuration in which inductor L1 and inductor L11 are connected in series becomes inductor L11A. The other configuration is the same as the corresponding parts in FIGS. 2 and 3 of the first embodiment, and detailed description will not be repeated.

[0065] Even in such a filter device including a single filter, by arranging the inductor connected to the input terminal and the inductor connected to the output terminal adjacent to each other within the main body, it is possible to increase the adjustment range of the passband width while reducing the effect on other filter characteristics.

[0066] [Embodiment 3] In the first and second embodiments, an example of a configuration in which the filter FLT1 includes one LC resonator and two trap inductors, that is, three inductors L11 to L13, has been described. However, in order to adjust the attenuation characteristics by adding an attenuation pole, more inductors may be included in the filter.

[0067] In the third embodiment, an example of a filter including four inductors as a whole will be described, in which two LC resonators are connected to a signal transmission path between an inductor connected to an input terminal and an inductor connected to an output terminal.

[0068] Fig. 11 is a diagram for explaining the arrangement of inductors included in a high-pass filter in the filter devices 100B and 100C according to Embodiment 3. Fig. 11 is a schematic diagram of a main body 110 viewed in a plan view from the normal direction.

[0069] 11, each of the filter devices 100B and 100C includes an additional LC resonant circuit including an inductor L14 in addition to the resonator including the inductor L13 in the signal transmission path between the inductor L11 and the inductor L12. That is, in the equivalent circuit, the inductors L11, L13, L14, and L12, or the inductors L11, L14, L13, and L12 are arranged in this order along the signal transmission path from the antenna terminal TA to the first terminal T1.

[0070] However, in the filter device 100B, the four inductors are arranged in the order of inductors L11, L12, L13, and L14 from the long side 113 toward the long side 114 of the body 110. That is, the inductor L12 connected to the output terminal is arranged between the inductors L11 and L13 and between the inductors L11 and L14, and the inductors L11 and L12 are arranged adjacent to each other.

[0071] In addition, in the filter device 100C, four of The inductors are arranged in the order of inductors L14, L11, L12, and L13 from the long side 113 to the long side 114 of the main body 110. That is, the inductor L11 connected to the input terminal is arranged between the inductor L14 and the inductor L12, and the inductor L11 and the inductor L12 are arranged adjacent to each other.

[0072] In this way, also for a filter including four inductors, as in the first and second embodiments, by arranging the inductor connected to the input terminal and the inductor connected to the output terminal adjacent to each other within the main body, it is possible to increase the adjustment range of the passband width while reducing the effect on other filter characteristics.

[0073] In addition, when the filter includes four or more inductors, the inductors L11 and L12 do not have to be directly adjacent to each other as long as the inductors L11 and L12 are not both arranged at both ends of the main body. Specifically, when the inductors L11, L14, L12, and L13 are arranged in this order from the long side 113 to the long side 114 of the main body 110, the distance between the inductors L11 and L12 can be made shorter than when the inductors L11 and L12 are arranged at both ends (in this order: inductors L11, L13, L14, and L12), and therefore it is possible to improve the adjustment margin of the passband width to some extent.

[0074] "Inductor L14" in the third embodiment corresponds to the "fourth inductor" in this disclosure.

[0075] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0076] 10 communication device, 20 high frequency front end circuit, 100, 100A to 100C, 100X, 200 filter device, 110 main body, ANT antenna device, C11 to C13, C21, C22 capacitors, DM directional mark, FLT1, FLT2 filter, GND ground terminal, IN input terminal, L1 ,L 11~L14, L11A, L21, L22 inductors, LNA1, LNA2 amplifier circuit, LY1~LY11 dielectric layer, OUT1 first output terminal, OUT2 second output terminal, P1, P2, PG, PL1~PL5, PL1A, PL2A, PL3A~PL3D, PL3X, PL3Y, PL3D, PL4A~PL4F, PL5A flat plate electrodes, PB1 branch point, PC1~PC4 capacitor electrodes, T1 first terminal, T2 second terminal, TA antenna terminal, V1~V3, V1A, VG1, VG2, VL1~VL5, VL1A, VL2A, VL3A~VL3D, VL3Y, VL3X, VL4A~VL4F, VL5A, VL5B vias.

Claims

1. A filter device for transmitting a signal from an input terminal to an output terminal, The main body, a first inductor, a second inductor and a third inductor provided on the body; a first capacitor connected to the first inductor and the second inductor; a second capacitor connected to the first inductor and the third inductor; a third capacitor connected to the second inductor and the third inductor; the first inductor is connected to the input terminal; the second inductor is connected to the output terminal; the first inductor and the second inductor are arranged in series in a signal transmission path connecting the input terminal and the output terminal, one end of the third inductor is connected to a signal transmission path between the first inductor and the second inductor, A filter device, wherein the first inductor and the second inductor are disposed adjacent to each other when viewed in a plan view from a normal direction of the main body.

2. The filter device according to claim 1 , wherein the second inductor is disposed between the first inductor and the third inductor when viewed in a plan view from a normal direction of the main body.

3. The filter device according to claim 1 , wherein the second inductor is magnetically coupled to the first inductor and the third inductor.

4. 4. The filter device according to claim 1, wherein at least one of the first inductor, the second inductor, and the third inductor is constituted by at least one plate electrode and a via connected to the plate electrode.

5. The filter device according to claim 1 , wherein at least one of the first inductor, the second inductor, and the third inductor includes a planar coil whose winding axis is in a normal direction to the main body.

6. a fourth inductor provided on the body and connected to a signal transmission path between the first inductor and the second inductor; The filter device according to claim 1 , wherein the second inductor is disposed between the first inductor and the fourth inductor when viewed in a plan view from a normal direction of the main body.

7. a fourth inductor provided on the body and connected to a signal transmission path between the first inductor and the second inductor; The filter device according to claim 1 , wherein the first inductor is disposed between the second inductor and the fourth inductor when viewed in a plan view from a normal direction of the main body.

8. A filter device for transmitting a signal from an input terminal to an output terminal, comprising: The main body, a first inductor, a second inductor, a third inductor and a fourth inductor provided on the body; the first inductor is connected to the input terminal; the second inductor is connected to the output terminal; the first inductor and the second inductor are arranged in series in a signal transmission path connecting the input terminal and the output terminal, one end of the third inductor is connected to a signal transmission path between the first inductor and the second inductor, the first inductor and the second inductor are disposed adjacent to each other when viewed in a plan view from a normal direction of the main body, the fourth inductor is connected to a signal transmission path between the first inductor and the second inductor, A filter device, wherein the second inductor is disposed between the first inductor and the fourth inductor when viewed in a plan view from a normal direction of the main body.

9. A filter device for transmitting a signal from an input terminal to an output terminal, comprising: The main body, a first inductor, a second inductor, a third inductor and a fourth inductor provided on the body; the first inductor is connected to the input terminal; the second inductor is connected to the output terminal; the first inductor and the second inductor are arranged in series in a signal transmission path connecting the input terminal and the output terminal, one end of the third inductor is connected to a signal transmission path between the first inductor and the second inductor, the first inductor and the second inductor are disposed adjacent to each other when viewed in a plan view from a normal direction of the main body, the fourth inductor is connected to a signal transmission path between the first inductor and the second inductor, A filter device, wherein the first inductor is disposed between the second inductor and the fourth inductor when viewed in a plan view from a normal direction of the main body.

10. A high-frequency front-end circuit comprising the filter device according to any one of claims 1 to 9.

11. a first filter configured to pass signals in a first frequency band; a second filter configured to pass signals in a second frequency band lower than the first frequency band; A diplexer, comprising the filter device according to any one of claims 1 to 9, as the first filter.

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