Filter device and high frequency front-end circuit including same

Abstract

To increase a degree of coupling between resonators in a stacked filter device including a plurality of stages of the resonators while suppressing an increase in device size.SOLUTION: A filter device 100 includes a main body 110, an input terminal T1, an output terminal T2, a ground terminal GND, and resonators RC2 and RC3. The resonators RC2 and RC3 are disposed in the main body 110, and transmit signals from the input terminal T1 to the output terminal T2 by electromagnetic field coupling to each other. The resonators RC2 and RC3 respectively include first paths connected to the ground terminal GND through capacitors C2 and C3 from nodes N2B and N3B, and second paths connected to the ground terminal GND without passing through the capacitors C2 and C3 from the nodes N2B and N3B. The second path of the resonator RC2 and the second path of the resonator RC3 are partially commonalized. The filter device 100 further includes a third path L23A connected to the node N2B of the resonator RC2 and the node N3B of the resonator RC3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a filter device and a high-frequency front-end circuit including the same, and more particularly to a structure for improving the filter characteristics of a filter device configured with a plurality of resonators. [Background technology]

[0002] WO 2022 / 071191 (Patent Document 1) discloses a stacked filter device including multiple resonators. In such a filter device, the filter characteristics can be adjusted by adjusting the degree of coupling between the resonators. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 071191 Summary of the Invention [Problem to be solved by the invention]

[0004] Increasing the degree of coupling between resonators can sometimes be achieved, for example, by adjusting the inductance value of the inductor that constitutes the target resonator. Increasing the inductance value requires lengthening the electrodes or vias that constitute the inductor. However, this increases the overall size of the device, which can make it impossible to achieve the desired product size in products that require compactness and low height.

[0005] Conversely, if the inductance value is adjusted to be small, the capacitance value of the capacitor that constitutes the resonator must be increased to achieve the desired resonance frequency. In this case, it may not be possible to secure the electrode area of ​​the capacitor or the impedance of the resonator may decrease, resulting in a situation where the desired filter characteristics cannot be obtained.

[0006] The present disclosure has been made to solve such problems, and its purpose is to increase the degree of coupling between resonators in a stacked filter device including multiple stages of resonators while suppressing an increase in device size. [Means for solving the problem]

[0007] A filter device according to a first aspect of the present disclosure includes a main body, an input terminal, an output terminal, a ground terminal, and first and second resonators. The first and second resonators are disposed in the main body and transmit signals from the input terminal to the output terminal by electromagnetically coupling with each other. Each of the first and second resonators includes a first path connected from a first node to the ground terminal via a capacitor, and a second path connected from the first node to the ground terminal without via a capacitor. The second path of the first resonator and the second path of the second resonator have a portion in common. The filter device further includes a third path connected to the first node of the first resonator and the first node of the second resonator.

[0008] A filter device according to a second aspect of the present disclosure includes an input terminal, an output terminal, a ground terminal, a first resonator, and a second resonator. The first resonator and the second resonator transmit a signal from the input terminal to the output terminal by electromagnetically coupling with each other. The first resonator includes a first capacitor connected between a first node and the ground terminal, a first inductor having one end connected to the first node, a second inductor connected to the other end of the first inductor, and a common inductor connected between the other end of the second inductor and the ground terminal. The second resonator includes a second capacitor connected between the second node and the ground terminal, a third inductor having one end connected to the second node, and a fourth inductor connected between the other end of the third inductor and the common inductor. The filter device further includes a fifth inductor connected between the other end of the first inductor and the other end of the third inductor.

[0009] A filter device according to a third aspect of the present disclosure includes a main body, an input terminal, an output terminal, a ground terminal, and fifth and sixth resonators. The fifth and sixth resonators are disposed in the main body and transmit signals from the input terminal to the output terminal by electromagnetically coupling with each other. The fifth resonator includes a third capacitor connected between a third node and the input terminal, a sixth inductor having one end connected to the third node, a seventh inductor connected to the other end of the sixth inductor, and a common inductor connected between the other end of the seventh inductor and the ground terminal. The sixth resonator includes: Output terminal and a ground terminal; and Output terminal an eighth inductor having one end connected to the sixth inductor, and a ninth inductor connected between the other end of the eighth inductor and the common inductor. The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor.

[0010] A filter device according to a fourth aspect of the present disclosure includes a main body, an input terminal, an output terminal, a ground terminal, a fifth resonator, and a seventh resonator. The fifth resonator and the seventh resonator are disposed in the main body and transmit signals from the input terminal to the output terminal by electromagnetically coupling with each other. The fifth resonator includes a third capacitor connected between a third node and the input terminal, a sixth inductor having one end connected to the third node, a seventh inductor connected to the other end of the sixth inductor, and a common inductor connected between the other end of the seventh inductor and the ground terminal. The seventh resonator includes a sixth capacitor connected between a fourth node and the output terminal, an eighth inductor having one end connected to the fourth node, and a ninth inductor connected between the other end of the eighth inductor and the common inductor. The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor. [Effects of the Invention]

[0011] In the filter device according to the present disclosure, in each of the two resonators, the paths (second paths) connected to the ground terminal without passing through a capacitor are connected to each other by a third path. With this configuration, it is possible to increase the degree of coupling between the resonators while suppressing an increase in the device size. [Brief explanation of the drawings]

[0012] [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. [Figure 2] 1 is an equivalent circuit diagram of a filter device according to a first embodiment. [Figure 3] 1 is an external perspective view of a filter device according to a first embodiment. [Figure 4] FIG. 4 is an exploded perspective view showing an example of a layered structure of the filter device of FIG. 3. [Figure 5] FIG. 10 is a diagram showing a comparative example 1 corresponding to the second and third stage filters of the filter device of the first embodiment. [Figure 6] 5A and 5B are diagrams illustrating the degree of coupling in the second and third stage filters of the filter device according to the first embodiment. [Figure 7] 4 is a diagram for explaining the relationship between the resonance frequency and the degree of coupling between resonators in the filter devices of the first embodiment and the first comparative example. FIG. [Figure 8] 5 is a diagram for explaining the filter characteristics of the filter device according to the first embodiment. FIG. [Figure 9] 3 is a schematic diagram of a second- and third-stage filter in the filter device of the first embodiment. FIG. [Figure 10] 10 is a schematic diagram of a second- and third-stage filter in a filter device according to a first modified example. FIG. [Figure 11] 10 is a schematic diagram of a second- and third-stage filter in a filter device according to a second modification. FIG. [Figure 12] 10 is a schematic diagram of a second- and third-stage filter in a filter device according to a third modification. FIG. [Figure 13] FIG. 10 is an equivalent circuit diagram of a filter device according to a second embodiment. [Figure 14] FIG. 10 is an equivalent circuit diagram of a filter device of Comparative Example 2. [Figure 15] FIG. 14 is a diagram obtained by converting the equivalent circuit of FIG. [Figure 16] 10 is a diagram illustrating a filter characteristic of the filter device according to the second embodiment. FIG. [Figure 17] FIG. 11 is an equivalent circuit diagram of a filter device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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 numerals, and description thereof will not be repeated.

[0014] [Embodiment 1] (Basic configuration of communication equipment) 1 is a block diagram of a communication device 10 having a high-frequency front-end circuit 20 to which the filter device of Embodiment 1 is applied. The communication device 10 is, for example, a mobile terminal such as a smartphone, or a mobile phone base station.

[0015] 1, a communication device 10 includes an antenna 12, a high-frequency front-end circuit 20, a mixer 30, a local oscillator 32, a D / A converter (DAC) 40, and an RF circuit 50. The high-frequency front-end circuit 20 also includes band-pass filters 22 and 28, an amplifier 24, and an attenuator 26. Although the description of FIG. 1 illustrates a case in which the high-frequency front-end circuit 20 includes a transmission circuit that transmits a high-frequency signal from the antenna 12, the high-frequency front-end circuit 20 may also include a reception circuit that receives a high-frequency signal via the antenna 12.

[0016] The communication device 10 upconverts a transmission signal transmitted from the RF circuit 50 to a high-frequency signal and radiates it from the antenna 12. The modulated digital signal output from the RF circuit 50, which is the transmission signal, is converted to an analog signal by the D / A converter 40. The mixer 30 upconverts the transmission signal, converted from digital to analog by the D / A converter 40, to a high-frequency signal by mixing it with an oscillation signal from the local oscillator 32. The bandpass filter 28 removes unwanted waves generated by the upconversion and extracts only the transmission signal in the desired frequency band. The attenuator 26 adjusts the intensity of the transmission signal. The amplifier 24 power-amplifies the transmission signal that has passed through the attenuator 26 to a predetermined level. The bandpass filter 22 removes unwanted waves generated during the amplification process and passes only signal components in the frequency band specified by the communication standard. The transmission signal that has passed through the bandpass filter 22 is radiated from the antenna 12.

[0017] A filter device according to the present disclosure can be employed as the bandpass filters 22, 28 in the communication device 10 described above.

[0018] (Configuration of filter device) Next, the detailed configuration of the filter device 100 according to the first embodiment will be described with reference to FIGS.

[0019] Fig. 2 is an equivalent circuit diagram of the filter device 100. Referring to Fig. 2, the filter device 100 includes an input terminal T1, an output terminal T2, and resonators RC1 to RC4. Each of the resonators RC1 to RC4 is an LC parallel resonator in which an inductor and a capacitor are connected in parallel.

[0020] The resonator RC1 includes inductors L1 and L5 connected in series between the input terminal T1 and the ground terminal GND, and a capacitor C1 connected in parallel to the inductors L1 and L5. A connection node N1A between the inductor L1 and the capacitor C1 is connected to the input terminal T1.

[0021] The resonator RC2 includes inductors L2A, L2B, L23B, and L5 connected in series, and a capacitor C2 connected in parallel to the inductors L2A, L2B, L23B, and L5. A connection node N2A between the inductor L2A and the capacitor C2 is connected to a connection node N1A (i.e., the input terminal T1) of the resonator RC1 via a capacitor C12.

[0022] The resonator RC3 includes inductors L3A, L3B, L23B, and L5 connected in series, and a capacitor C3 connected in parallel to the inductors L3A, L3B, L23B, and L5. A connection node N3A between the inductor L3A and the capacitor C3 is connected to a connection node N4A (i.e., the output terminal T2) of the resonator RC4 via a capacitor C34. The connection node N3A is also connected to a connection node N2A of the resonator RC2 via a capacitor C23. Furthermore, an inductor L23A is connected between a connection node N3B between the inductors L3A and L3B and a connection node N2B between the inductors L2A and L2B in the resonator RC2.

[0023] The resonator RC4 includes inductors L4 and L5 connected in series between the output terminal T2 and the ground terminal GND, and a capacitor C4 connected in parallel to the inductors L4 and L5. A connection node N4A between the inductor L4 and the capacitor C4 is connected to the output terminal T2. The connection node N4A is also connected to the connection node N1A of the resonator RC1 (i.e., the input terminal T1) via a capacitor C14.

[0024] As described above, the inductor L5 is shared by the resonators RC1 to RC4, and the inductor L23B is shared by the resonators RC2 and RC3.

[0025] The resonators are magnetically coupled to each other. Thus, the filter device 100 has a configuration in which four stages of resonators that are magnetically coupled to each other are arranged between the input terminal T1 and the output terminal T2. By adjusting the resonant frequency of each resonator, the filter device 100 functions as a bandpass filter that passes signals in a desired frequency band.

[0026] The connection nodes N2B and N3B in FIG. 2 are an example of a “first node” in the present disclosure. In this case, in the resonator RC2, the path from the connection node N2B to the ground terminal GND via the inductor L2A and the capacitor C2 corresponds to the “first path” in the present disclosure. Also, the path from the connection node N2B to the ground terminal GND via the inductors L2B, L23B, and L5 corresponds to the “second path” in the present disclosure. Similarly, in the resonator RC3, the path from the connection node N3B to the ground terminal GND via the inductor L3A and the capacitor C3 corresponds to the “first path” in the present disclosure. Also, the path from the connection node N3B to the ground terminal GND via the inductors L3B, L23B, and L5 corresponds to the “second path” in the present disclosure. And, the inductor L23A connecting the connection node N2B and the connection node N3B corresponds to the “third path” in the present disclosure.

[0027] The capacitor C12 connected to the resonators RC1 and RC2 may be connected between the connection nodes N1A and N2B in Fig. 2. The capacitor C34 connected to the resonators RC3 and RC4 may be connected between the connection nodes N3B and N4A in Fig. 2.

[0028] FIG. 3 is an external perspective view of the filter device 100, and FIG. 4 is an exploded perspective view showing an example of the layered structure of the filter device 100. As shown in FIG.

[0029] 3 and 4, the filter device 100 includes a rectangular or approximately rectangular parallelepiped main body 110 in which a plurality of dielectric layers LY1 to LY10 are stacked in a stacking direction. The dielectric layers LY1 to LY10 are formed of ceramics such as low-temperature co-fired ceramics (LTCC) or resin. Inside the main body 110, inductors and capacitors of an LC parallel resonator are formed by a plurality of electrodes provided on each dielectric layer and a plurality of vias provided between the dielectric layers. In this specification, the term "via" refers to a conductor provided in a dielectric layer to connect electrodes provided on different dielectric layers. The vias are formed by, for example, conductive paste, plating, and / or metal pins.

[0030] In the following description, the stacking direction of the dielectric layers LY1 to LY10 in the 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 the main body 110 is referred to as the "X-axis direction," and the direction along the short side of the main body 110 is referred to as the "Y-axis direction." In the following, the positive direction of the Z-axis in each drawing may be referred to as the upper side, and the negative direction may be referred to as the lower side.

[0031] A direction mark DM for specifying the orientation of the filter device 100 is arranged on an upper surface 111 (dielectric layer LY1) of the main body 110. External terminals (an input terminal T1, an output terminal T2, and a ground terminal GND) for connecting the filter device 100 to an external device are arranged on a lower surface 112 (dielectric layer LY10) of the main body 110. The input terminal T1, the output terminal T2, and the ground terminal GND are each a flat electrode, and are LGA (Land Grid Array) terminals regularly arranged on the lower surface 112 of the main body 110.

[0032] As described with reference to FIG. 2, the filter device 100 includes resonators RC1 to RC4, which are four-stage LC parallel resonators. More specifically, the resonator RC1 includes vias V10, V11, and V12, a capacitor electrode PC1, and plate electrodes PL10A, PL10B, PL11A, and PL11B. The resonator RC2 includes a via V20, a capacitor electrode PC2A, and plate electrodes PL23A and PL23B. The resonator RC3 includes a via V30, a capacitor electrode PC3A, and plate electrodes PL23A and PL23B. The resonator RC4 includes vias V40, V41, and V42, a capacitor electrode PC4, and plate electrodes PL40A, PL40B, PL41A, and PL41B.

[0033] The input terminal T1 is connected by a via V10 to a capacitor electrode PC1 arranged on a dielectric layer LY8. The capacitor electrode PC1 is a substantially rectangular electrode extending in the X-axis direction. The capacitor electrode PC1 is connected by a via V11 to a plate electrode PL10A arranged on a dielectric layer LY5 and a plate electrode PL10B arranged on a dielectric layer LY4.

[0034] The plate electrodes PL10A and PL10B are strip-shaped electrodes with their winding axes along the Z-axis and have substantially the same shape. One end of each of the plate electrodes PL10A and PL10B is connected to a via V11. The other ends of each of the plate electrodes PL10A and PL10B are connected by a via V12 to a plate electrode PL11A disposed on the dielectric layer LY3 and a plate electrode PL11B disposed on the dielectric layer LY2.

[0035] The plate electrodes PL11A and PL11B are strip-shaped electrodes with their winding axes along the Z-axis and have substantially the same shape. One ends of the plate electrodes PL11A and PL11B are connected to a via V12. The other ends of the plate electrodes PL11A and PL11B are connected by a via VG1 to a ground electrode PG disposed on the dielectric layer LY9 and to a ground terminal GND disposed on the lower surface 112 of the dielectric layer LY10.

[0036] Furthermore, a substantially rectangular capacitor electrode PC2B is disposed on the dielectric layer LY8 adjacent to the capacitor electrode PC1 in the positive direction of the Y-axis. The capacitor electrodes PC1 and PC2B are capacitively coupled to each other. The capacitor electrode PC2B is connected to a ground terminal GND disposed on the dielectric layer LY10 by vias VG2. The capacitor electrode PC2B is also connected to a ground electrode PG disposed on the dielectric layer LY9 by a plurality of vias VG5. The ground electrode PG is connected to a ground terminal GND disposed on the dielectric layer LY10 by vias VG4.

[0037] The vias V10, V11, and V12 and the plate electrodes PL10A, PL10B, PL11A, and PL11B form the inductor L1 in Fig. 2. The via VG1 forms the inductor L5 in Fig. 2. The capacitor electrodes PC1 and PC2B form the capacitor C1 in Fig. 2. That is, the vias V10, V11, V12, and VG1, the plate electrodes PL10A, PL10B, PL11A, and PL11B, and the capacitor electrodes PC1 and PC2B form the resonator RC1.

[0038] When viewed in a plane from the stacking direction, the capacitor electrode PC1 partially overlaps with a substantially L-shaped capacitor electrode PC2A disposed on the adjacent dielectric layer LY7. The capacitor electrodes PC1 and PC2A form the capacitor C12 in FIG. 2. When viewed in a plane from the stacking direction, the capacitor electrode PC2A also partially overlaps with a capacitor electrode PC2B disposed on the dielectric layer LY8. The capacitor electrodes PC2A and PC2B form the capacitor C2 in FIG. 2.

[0039] Furthermore, the capacitor electrode PC2A is connected by a via V20 to a plate electrode PL23A arranged on the dielectric layer LY3 and a plate electrode PL23B arranged on the dielectric layer LY2. Each of the plate electrodes PL23A and PL23B has a substantially Y-shape with three ends, with a first end connected to the via V20, a second end connected to the via V30, and a third end connected to the via VG1.

[0040] The via V20 forms the inductor L2A in Fig. 2. The path between the first end and the connection point of the paths from the first end, second end, and third end of the plate electrodes PL23A, PL23B and the first end forms the inductor L2B in Fig. 2. The path from the connection point to the third end forms the inductor L23B in Fig. 2.

[0041] That is, the vias V20, VG1, the plate electrodes PL23A, PL23B, and the capacitor electrodes PC2A, PC2B form the resonator RC2 in FIG.

[0042] A via V30 connected to the second ends of the plate electrodes PL23A and PL23B is connected to a capacitor electrode PC3A disposed on a dielectric layer LY7. The capacitor electrode PC3A has a substantially L-shape similar to the capacitor electrode PC2A. When viewed from above in the stacking direction, the capacitor electrode PC3A partially overlaps with each of the capacitor electrodes PC3B and PC4 disposed on the dielectric layer LY8. Each of the capacitor electrodes PC3B and PC4 is a substantially rectangular electrode extending in the X-axis direction and is disposed adjacent to each other in the Y-axis direction. The capacitor electrodes PC3B and PC4 are capacitively coupled to each other.

[0043] The capacitor electrode PC4 is connected by a via V40 to an output terminal T2 disposed on the lower surface 112 of the dielectric layer LY10. The capacitor electrode PC3B is connected by a via VG3 to a ground terminal GND disposed on the dielectric layer LY10. The capacitor electrode PC3B is also connected by a plurality of vias VG6 to a ground electrode PG disposed on the dielectric layer LY9.

[0044] Capacitor C3 in FIG. 2 is formed by capacitor electrodes PC3A and PC3B. Capacitor C34 in FIG. 2 is formed by capacitor electrodes PC3A and PC4. Inductor L3A in FIG. 2 is formed by via V30. Inductor L3B is formed by the path between the connection point of plate electrodes PL23A and PL23B and the second end. As described above, inductor L23B in FIG. 2 is formed by the path between the connection point of plate electrodes PL23A and PL23B and the third end, and inductor L5 in FIG. 2 is formed by via VG1.

[0045] That is, the vias V30, VG1, the plate electrodes PL23A, PL23B, and the capacitor electrodes PC3A, PC3B form the resonator RC3 in FIG.

[0046] The capacitor electrode PC4 is connected by a via V41 to a plate electrode PL40A disposed on the dielectric layer LY5 and a plate electrode PL40B disposed on the dielectric layer LY4.

[0047] The plate electrodes PL40A and PL40B are strip-shaped electrodes with their winding axes along the Z-axis and have substantially the same shape. One end of each of the plate electrodes PL40A and PL40B is connected to a via V41. The other ends of each of the plate electrodes PL40A and PL40B are connected by a via V42 to a plate electrode PL41A disposed on the dielectric layer LY3 and a plate electrode PL41B disposed on the dielectric layer LY2.

[0048] The plate electrodes PL41A and PL41B are strip-shaped electrodes with their winding axes along the Z-axis and have substantially the same shape. One end of each of the plate electrodes PL41A and PL41B is connected to a via V42. The other ends of each of the plate electrodes PL41A and PL41B are connected by a via VG1 to a ground electrode PG disposed on the dielectric layer LY9 and to a ground terminal GND disposed on the lower surface 112 of the dielectric layer LY10.

[0049] The vias V40, V41, and V42 and the plate electrodes PL40A, PL40B, PL41A, and PL41B form the inductor L4 in Fig. 2. The via VG1 forms the inductor L5 in Fig. 2. The capacitor electrodes PC3B and PC4 form the capacitor C4 in Fig. 2. That is, the vias V40, V41, V42, and VG1, the plate electrodes PL40A, PL40B, PL41A, and PL41B, and the capacitor electrodes PC3B and PC4 form the resonator RC4.

[0050] Each of the capacitor electrodes PC2A and PC3A arranged on the dielectric layer LY7 is located on the dielectric layer LY7 when viewed from above in the lamination direction. 6 2. The capacitor electrodes PC2A, PC3A, and PC23 partially overlap with a capacitor electrode PC23 having a substantially rectangular shape that is disposed on the substrate 10. The capacitor electrodes PC2A, PC3A, and PC23 form the capacitor C23 in FIG.

[0051] When viewed in a plan view from the stacking direction, each of the capacitor electrodes PC1 and PC4 arranged on the dielectric layer LY8 partially overlaps with the strip-shaped capacitor electrode PC14 arranged on the dielectric layer LY9. The capacitor electrodes PC1, PC4, and PC14 form the capacitor C14 in FIG.

[0052] On the dielectric layer LY3, the first and second terminals of the plate electrode PL23A are connected by a strip-shaped plate electrode PL50A extending in the X-axis direction. On the dielectric layer LY2, the first and second terminals of the plate electrode PL23B are connected by a strip-shaped plate electrode PL50B extending in the X-axis direction. The plate electrodes PL50A and PL50B form the inductor L23A in FIG. 2.

[0053] On the dielectric layer LY3, a ring-shaped structure is formed by the plate electrodes PL23A and PL50A. Similarly, on the dielectric layer LY2, a ring-shaped structure is formed by the plate electrodes PL23B and PL50B. As will be described below, by arranging the inductor L23A formed by the plate electrodes PL50A and PL50B, it is possible to strengthen the coupling between the resonators RC2 and RC3.

[0054] In the following description, the plate electrodes PL50A and PL50B may be collectively referred to as "plate electrode PL50," and the plate electrodes PL23A and PL23B may be collectively referred to as "plate electrode PL23."

[0055] (Explanation of inter-resonator coupling) The degree of coupling between the resonator RC2 and the resonator RC3 in the filter device 100 of the first embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 shows the case of the filter device 100X of the first comparative example, and Fig. 6 shows the case of the filter device 100 of the first embodiment.

[0056] For ease of explanation, an equivalent circuit of only the configuration corresponding to the resonators RC2 and RC3 is shown in Figures 5 and 6. Furthermore, the portions corresponding to the connection nodes N2A and N3A in Figure 2 are shown as an input terminal T10 and an output terminal T20, respectively, in Figures 5 and 6.

[0057] 5, inductors L10 and L20 are connected in series between input terminal T10 and output terminal T20. Inductor L30 is connected between ground terminal GND and a connection node N10 between inductors L10 and L20. Capacitor C10 is connected between input terminal T10 and ground terminal GND, and capacitor C20 is connected between output terminal T20 and ground terminal GND.

[0058] 2, inductor L10 corresponds to inductors L2A and L2B, and inductor L20 corresponds to inductors L3A and L3B. In addition, inductor L30 corresponds to inductors L23B and L5. Furthermore, capacitors C10 and C20 correspond to capacitors C2 and C3, respectively. That is, in the filter device 100X, "inductor L23A" is removed from the resonators RC2 and RC3 in FIG. 2.

[0059] 6, inductors L10A and L10B on the left correspond to inductors L2A and L2B, respectively, in Fig. 2, and inductors L20A and L20B correspond to inductors L3A and L3B, respectively, in Fig. 2. Inductor L12 corresponds to inductor L23A in Fig. 2.

[0060] 5, the degree of coupling between the resonators RC2 and RC3 can generally be expressed by the ratio of the inductance value of the inductor L30 to the inductance value of the inductor L10 (L30 / L10), or the ratio of the inductance value of the inductor L30 to the inductance value of the inductor L20 (L30 / L20). Therefore, in order to increase the degree of coupling between the resonators RC2 and RC3 in FIG. 5, it is possible to increase the inductance value of the inductor L30 or decrease the inductance values ​​of the inductors L10 and L20.

[0061] Increasing the inductance value of inductor L30 requires increasing the inductance value of via VG1 in the configuration shown in Figure 4. In other words, the length of via VG1 must be increased, which increases the dimension of the filter device body in the Z-axis direction. This may hinder efforts to miniaturize the device or may make it difficult to achieve due to dimensional constraints on the device.

[0062] On the other hand, if the inductance values ​​of inductors L10 and L20 are reduced, the total inductance value of the resonator becomes smaller. Therefore, to achieve the desired resonant frequency of the resonator, it is necessary to increase the capacitance values ​​of capacitors C10 and C20 in the resonator. In this case, it is necessary to increase the area of ​​the capacitance electrodes constituting capacitors C10 and C20. However, increasing the area of ​​the capacitance electrodes requires an increase in the area of ​​the dielectric layer, which may result in an increase in the size of the device or make it difficult to achieve the required device dimensions. Furthermore, if the inductance value of the resonator is reduced and the capacitance value is increased, the impedance of the resonator itself may decrease, which may result in an inability to achieve the required filter characteristics.

[0063] On the other hand, the configuration of the first embodiment as shown in the left diagram of Fig. 6 is configured such that a Δ connection (dashed line area AR10) consisting of inductors L10B, L20B, and L12 is arranged between inductors L10A, L20A, and L30. When this area AR10 undergoes a Δ-Y transformation, it becomes equivalent to a configuration in which inductor L10C connected to inductor L10A, inductor L20C connected to inductor L20A, and inductor L30C connected to inductor L30 are connected at connection node N20, as shown in the right diagram of Fig. 6.

[0064] When a Δ-Y transformation is performed, the inductance value of inductor L10C becomes smaller than that of inductor L10B (L10B>L10C), and the inductance value of inductor L20C becomes smaller than that of inductor L20B (L20B>L20C).

[0065] Comparing the configuration of the right diagram in Fig. 6 with the configuration of the filter device 100X in Fig. 5, inductors L10A and L10C correspond to inductor L10 of the filter device 100X, inductors L20A and L20C correspond to inductor L20 of the filter device 100X, and inductors L30 and L30C correspond to inductor L30 of the filter device 100X. As described above, since L10B>L10C and L20B>L20C and L30C>0, adding inductor L12 to the filter device 100 is equivalent to a configuration in which the inductance values ​​of inductors L10 and L20 of the filter device 100X are reduced and the inductance value of inductor L30 is increased. Therefore, the degree of coupling between resonators RC2 and RC3 in the filter device 100 can be increased compared to that in the filter device 100X.

[0066] In this case, since this can be achieved by arranging the plate electrodes PL50A and PL50B as shown in Fig. 4, it is possible to prevent the device from becoming large. Furthermore, by appropriately setting the inductance values ​​of inductors L10B, L20B, and L12, it is possible to prevent a decrease in impedance.

[0067] Fig. 7 is a diagram illustrating the relationship between the resonant frequency and the degree of inter-resonator coupling in the filter devices of the first embodiment and the comparative example 1. The upper part of Fig. 7 shows an internal perspective view of the resonators RC2 and RC3 in the filter device 100 of the first embodiment and the filter device 100X of the comparative example 1. The lower part of Fig. 7 shows a graph representing the relationship between the resonant frequency and the degree of inter-resonator coupling in the filter devices 100 and 100X having approximately the same device size.

[0068] 4, in the filter device 100, a ring-shaped structure is formed on the dielectric layers LY2 and LY3 by the plate electrode PL23 connecting the vias V20, V30, and VG1 and the plate electrode PL50 connecting the vias V20 and V30. On the other hand, in the filter device 100X, the vias V20, V30, and VG1 are connected by the plate electrode PL23X having a substantially T-shape.

[0069] 7, the horizontal axis represents the resonant frequency, and the vertical axis represents the inter-resonator coupling between the resonators RC2 and RC3. In the graph, the solid line LN10 represents the filter device 100 of the first embodiment, and the dashed line LN11 represents the filter device 100X of the first comparative example.

[0070] 7, when the filter devices 100 and 100X have similar device sizes, the filter device 100 has a higher inter-resonator coupling degree at a resonant frequency of 6.0 GHz or higher. For example, at a resonant frequency of 6.5 GHz, the filter device 100 has a coupling degree of 0.50, while the filter device 100X has a coupling degree of 0.30.

[0071] On the other hand, in order to obtain a degree of coupling of 0.50 in the filter device 100X, the resonant frequency needs to be set to a higher frequency of 8.0 GHz. Generally, as the resonant frequency increases, the required circuit element values ​​decrease, resulting in a smaller device size. Conversely, as the resonant frequency decreases, the required circuit element values ​​increase, resulting in a larger device size. Therefore, for example, if a desired resonant frequency is 6.5 GHz, attempting to obtain a degree of coupling of 0.50 using the configuration of the filter device 100X results in a device size larger than that of the filter device 100. Conversely, if the desired resonant frequency is 8.0 GHz, using the configuration of the filter device 100 already provides a sufficient degree of coupling, so the resonant frequency can be increased and the device size can be further reduced by reducing the circuit element values. In other words, by using the configuration of the filter device 100, which can achieve an equivalent degree of coupling at a lower resonant frequency, the overall device size can be reduced.

[0072] (filter characteristics) Fig. 8 is a diagram illustrating the filter characteristics of filter device 100 according to the first embodiment. In Fig. 8, the horizontal axis represents frequency, and the vertical axis represents the insertion loss of filter device 100.

[0073] Fig. 8 shows the change in filter characteristics when the length of the plate electrode PL50 in the X-axis direction, in other words, the spacing between the vias V20 and V30 that respectively constitute resonators RC2 and RC3, is changed. More specifically, the dashed-dotted line LN22 in Fig. 8 represents the characteristics when the vias V20 and V30 are positioned at the farthest distance as shown in Fig. 4, and the dashed line LN21 represents the characteristics when the vias V20 and V30 are positioned closer along the X-axis direction than in Fig. 4. Furthermore, the solid line LN20 represents the characteristics when the vias V20 and V30 are positioned even closer than the positions represented by the dashed line LN21.

[0074] As shown in FIG. 8, it can be seen that the shorter the distance between the vias V20 and V30, in other words, the stronger the degree of coupling between the resonators RC2 and RC3, the wider the frequency bandwidth (passband) of the filter device.

[0075] In addition, in the solid line LN20, the loss is somewhat large on the high frequency side of the passband (near f1), but this can be improved by adjusting the inductance value by changing the line width of the flat electrode and / or by adjusting the capacitance value by changing the area of ​​the capacitor electrode.

[0076] As described above, in a stacked filter device including multiple resonators, by providing an inductor connecting two resonators to form a ring structure, it is possible to increase the degree of coupling between the resonators while suppressing an increase in the device size, thereby enabling the desired characteristics of the filter device to be achieved.

[0077] In the above description, a configuration for increasing the degree of coupling between the second and third resonators of a filter device including four resonators has been described as an example, but the above configuration can be applied to any two resonators in the four-stage resonators.

[0078] The "resonators RC2" and "resonators RC3" in the first embodiment correspond to the "first resonator" and "second resonator," respectively, in the present disclosure. The "resonators RC1" and "resonators RC4" in the first embodiment correspond to the "third resonator" and "fourth resonator," respectively, in the present disclosure. The "via VG1" in the first embodiment corresponds to the "common via" in the present disclosure. The "capacitor electrode PC2A" and "capacitor electrode PC3A" in the first embodiment correspond to the "first capacitor electrode" and "second capacitor electrode," respectively, in the present disclosure. The "via V20" and "via V30" in the first embodiment correspond to the "first via" and "second via," respectively, in the present disclosure. The "plate electrodes PL23A, PL23B" in the first embodiment correspond to the "first plate electrode" and "second plate electrode" in the present disclosure. The "plate electrodes PL50A and PL50B" in the first embodiment correspond to the "third plate electrode" in the present disclosure.

[0079] 2, "capacitor C2" and "capacitor C3" in the first embodiment correspond to the "first capacitor" and "second capacitor" in the present disclosure, respectively. "Inductor L2A," "inductor L2B," "inductor L3A," "inductor L3B," and "inductor L23A" in the first embodiment correspond to the "first inductor" to "fifth inductor" in the present disclosure, respectively. "Inductor L23B" and "inductor L5" in the first embodiment correspond to the "common inductor" in the present disclosure.

[0080] [Variations] Next, the configuration of a filter device according to a modification of the first embodiment will be described with reference to Fig. 9 to Fig. 12. Fig. 9 to Fig. 12 are schematic diagrams that briefly illustrate only the resonators RC2 and RC3 in Fig. 2.

[0081] Fig. 9 corresponds to the filter device 100 of Fig. 4 and shows the annular structure formed in the dielectric layers LY2 and LY3 of Fig. 4. Furthermore, the capacitor electrodes PC2B and PC3B that face the capacitor electrodes PC2A and PC3A are omitted and shown as facing the ground electrode PG. In the filter device 100, the plate electrodes PL50 and PL23 that form the annular structure are configured with wiring patterns arranged on the same dielectric layer.

[0082] (Variation 1) In Modification 1, an example will be described in which the portion forming the annular structure is configured by wiring patterns arranged on different dielectric layers and vias connecting them.

[0083] Fig. 10 is a diagram showing a filter device 100A of Modification 1. In the filter device 100A, the portion corresponding to the plate electrode PL23 in the filter device 100 of Fig. 9 is formed by plate electrodes PL20, PL30, P23 and vias VL20, VL30.

[0084] The plate electrode PL20 is a strip-like electrode with a substantially rectangular shape, and extends in the negative direction of the Y axis from the end of the plate electrode PL50 to which the via V20 is connected. Similarly, the plate electrode PL30 is a strip-like electrode with a substantially rectangular shape, and extends in the negative direction of the Y axis from the end of the plate electrode PL50 to which the via V30 is connected.

[0085] The plate electrode P23 is disposed on a dielectric layer between the dielectric layer on which the plate electrodes PL20 and PL30 are disposed and the dielectric layer on which the ground electrode PG is disposed. The plate electrode P23 is a substantially rectangular strip electrode extending in the X-axis direction, and one end of the plate electrode P23 is connected to the end of the plate electrode PL20 facing the negative Y-axis direction by a via VL20. The other end of the plate electrode P23 is connected to the end of the plate electrode PL30 facing the negative Y-axis direction by a via VL30. The plate electrode P23 is then connected to the ground electrode PG by a via VG1.

[0086] In the filter device 100A, the inductor constituting the resonator RC2 is formed by vias V20, VL20 and plate electrodes PL20, P23, and the inductor constituting the resonator RC3 is formed by vias V30, VL30 and plate electrodes PL30, P23. The resonators RC2 and RC3 are connected to each other by the plate electrode PL50, which corresponds to the inductor L23A in Fig. 2. That is, by connecting the plate electrode P23, which is arranged on a different dielectric layer from the plate electrodes PL20, PL30, and PL50, using the vias VL20 and VL30, a ring structure is formed across multiple layers.

[0087] In this way, also in the filter device 100A, the inductor that connects the resonators RC2 and RC3 is disposed, forming a ring structure, thereby making it possible to strengthen the degree of coupling between the resonators RC2 and RC3.

[0088] Note that "via VG1" in Modification 1 corresponds to "common via" in the present disclosure. "Plate electrode P23" in Modification 1 corresponds to "common electrode" in the present disclosure. "Via V20," "Via VL20," "Via V30," and "Via VL30" in Modification 1 correspond to "third via," "fourth via," "fifth via," and "sixth via," respectively, in the present disclosure. "Capacitor electrode PC2A" and "capacitor electrode PC3A" in Modification 1 correspond to "third via," "fourth via," "fifth via," and "sixth via," respectively. 」 correspond to the "third capacitor electrode" and the "fourth capacitor electrode" in this disclosure. The "plate electrode PL20," "plate electrode PL30," and "plate electrode PL50" in Modification 1 correspond to the "fourth plate electrode," "fifth plate electrode," and "sixth plate electrode" in this disclosure, respectively.

[0089] (Variation 2) In the filter device 100 of Figure 9, an example has been described in which both the ground electrode that constitutes the capacitor in each resonator and the ground electrode to which the inductor of each resonator is connected are configured with a ground electrode PG arranged on the underside 112 of the main body 110.

[0090] In variant example 2, a configuration is described in which ground electrodes are arranged on the upper surface 111 and the lower surface 112 of the main body 110, one of the ground electrodes is used to form the capacitor of the resonator, and the other ground electrode is connected to the inductor of each resonator.

[0091] 11 is a diagram showing a filter device 100B of Modification 2. In filter device 100B, a ground electrode PG1 is arranged on a lower surface 112 side of a main body 110, and a ground electrode PG2 is arranged on an upper surface 111 side. The ground electrodes PG1 and PG2 are connected to each other by a via (not shown), and are further connected to a ground terminal GND.

[0092] A capacitor electrode PC2A constituting the capacitor C2 of the resonator RC2 and a capacitor electrode PC3A constituting the capacitor C3 of the resonator RC3 are disposed opposite to the ground electrode PG1. The capacitor electrode PC2A is connected to the ground electrode PG2 by a via V20A. The capacitor electrode PC3A is connected to the ground electrode PG2 by a via V30A.

[0093] The vias V20A and V30A are connected to each other by a substantially rectangular plate electrode PL23C and also by a plate electrode PL50B that is disposed on a dielectric layer between the dielectric layer on which the plate electrode PL23C is disposed and the dielectric layer on which the capacitor electrodes PC2A and PC3A are disposed.

[0094] In the filter device 100B, the portion of the via V20A between the capacitor electrode PC2A and the plate electrode PL50B corresponds to the via V20 in the filter device 100 of Fig. 9. The portion of the via V30A between the capacitor electrode PC3A and the plate electrode PL50B corresponds to the via V30 in the filter device 100 of Fig. 9. The portions of the vias V20A and V30A between the plate electrode PL50B and the plate electrode PL23C and the portion formed by the plate electrode PL23C correspond to the plate electrode PL23 in the filter device 100 of Fig. 9. The portion of the vias V20A and V30A between the plate electrode PL23C and the ground electrode PG2 corresponds to the via VG1 in the filter device 100 of Fig. 9. The plate electrode PL50B corresponds to the plate electrode PL50 in the filter device 100 of Fig. 9. That is, the filter device 100B has a configuration substantially equivalent to that of the filter device 100 shown in FIG. 9, and the vias V20A and V 30A A ring structure is formed by the plate electrodes PL23C and PL50B.

[0095] In this way, by placing two resonators RC2 and RC3 between two ground electrodes and connecting these resonators RC2 and RC3 with an inductor (plate electrode PL50B), the degree of coupling between resonator RC2 and resonator RC3 can be strengthened.

[0096] In the filter device 100B, the via portion that connects the plate electrode PL23C and the ground electrode PG2 may be shared.

[0097] (Variation 3) In the third modification, a configuration will be described in which the capacitor of the resonator is not provided with individual capacitor electrodes, but is formed by a capacitance component between a wiring pattern forming a ring structure and a ground electrode.

[0098] 12 is a diagram showing a filter device 100C of Modification 3. In the filter device 100C, resonators RC2 and RC3 are formed by plate electrodes PL20C, PL30C, PL23D, and PL50C and vias VG1A and VG1B arranged on the same dielectric layer.

[0099] Each of the plate electrodes PL20C and PL30C is a strip-shaped electrode having a substantially rectangular shape extending in the Y-axis direction. The end of the plate electrode PL20C in the negative direction of the Y-axis is connected to the ground electrode PG by a via VG1A, and the end in the positive direction of the Y-axis is an open end. Similarly, the end of the plate electrode PL30C in the negative direction of the Y-axis is connected to the ground electrode PG by a via VG1A. 1B and the end in the positive direction of the Y axis is an open end.

[0100] The plate electrodes PL23D and PL50C are strip-shaped electrodes with a substantially rectangular shape extending in the X-axis direction. The plate electrodes PL20C and PL30C are connected to each other by the plate electrode PL23D at a position closer to the end in the negative direction of the Y-axis. The plate electrodes PL20C and PL30C are also connected to each other by the plate electrode PL50C at a position closer to the positive direction of the Y-axis than the plate electrode PL23D. In other words, a ring structure is formed by the plate electrodes PL20C, PL30C, PL23D, and PL50C.

[0101] In the filter device 100C, the capacitance components between the plate electrodes PL20C, PL30C and the ground electrode PG form the capacitors of the resonators, and the capacitance components and the inductors formed by the plate electrodes form the resonators RC2, RC3.

[0102] Even in such a configuration, the two resonators RC2 and RC3 are connected by an inductor to form a ring structure, thereby making it possible to strengthen the degree of coupling between the resonators RC2 and RC3.

[0103] In the filter device 100C, vias connecting the plate electrode PL23D and the ground electrode PG may be arranged in place of the vias VG1A and VG1B. Furthermore, in order to ensure a capacitance value between the plate electrodes PL20C and PL30C and the ground electrode PG, capacitor electrodes wider than the plate electrodes PL20C and PL30C may be provided at the open ends of the plate electrodes PL20C and PL30C.

[0104] [Embodiment 2] In the second embodiment, a filter device in which some of the resonators have different configurations will be described.

[0105] FIG. 13 is an equivalent circuit diagram of a filter device 200 according to the second embodiment. The filter device 200 is generally a two-stage filter device in which two resonators RC11A and RC12 are arranged between an input terminal T10 and an output terminal T20. The filter device 200 may be used alone in a two-stage configuration as shown in FIG. 13, or may be used as a second or third stage resonator in a four-stage filter device as in the first embodiment. To make it easier to understand the correspondence with the first embodiment, the filter device 200 shown in FIG. 13 and FIGS. 14 and 15 described later are used as equivalent circuits. Figure 15, In FIG. 17, the same reference numerals are used as in the circuits of FIG.

[0106] 13, in filter device 200, resonator RC11A includes a capacitor C10A and inductors L10A, L10B, and L30. One end of capacitor C10A is connected to input terminal T10. Inductors L10A, L10B, and L30 are connected in series in this order between the other end of capacitor C10A and ground terminal GND.

[0107] The resonator RC12 has a configuration similar to that of the resonator RC3 in Fig. 6 and includes a capacitor C20 and inductors L20A, L20B, and L30. The capacitor C20 is connected between the output terminal T20 and the ground terminal GND. The inductors L20A, L20B, and L30 are connected in series in this order between the output terminal T20 and the ground terminal GND. That is, the series-connected inductors L20A, L20B, and L30 are connected in parallel with the capacitor C20 between the output terminal T20 and the ground terminal GND. The inductor L30 is also used by the resonator RC11A.

[0108] A capacitor C30 is connected between a connection node N31 between the capacitor C10A and the inductor L10A and the output terminal T20. An inductor L12 is connected between a connection node N33 between the inductors L10A and L10B and a connection node N34 between the inductors L20A and L20B. The inductors L12, L10B, and L20B form a ring-shaped structure (area AR10) similar to the filter device 100 of the first embodiment. Note that the capacitor C30 is not necessarily required in the filter device 200, and the filter device 200 may be configured without the capacitor C30.

[0109] FIG. 14 is an equivalent circuit diagram of a filter device 200X of Comparative Example 2. The filter device 200X basically has the same configuration as the second and third resonators of the filter device 100 of the first embodiment. resonator The capacitor C30 in the filter device 200X corresponds to the capacitor C23 in the filter device 100 (see FIG. 2 ) corresponds to

[0110] That is, compared to the filter device 200X of the second comparative example, the filter device 200 of the second embodiment has a configuration in which the capacitor C10 is removed and a capacitor C10A is added between the filter device 200 and the input terminal T10.

[0111] Figure 15 shows the 13 The inductor L10D in FIG. 13 15 corresponds to the inductors L10A, L10B, and L30 in FIG. 13 15 corresponds to the inductors L10A, L12, and L20A in FIG. 13 These correspond to inductors L20A, L20B, and L30 in the figure.

[0112] That is, the filter device 200 corresponds to a configuration in which a high-pass filter (HPF) constituted by capacitors C10A, C30 and inductors L10D, L12A included in the area AR20 of FIG. 15, and a band-pass filter (BPF) constituted by an LC parallel resonator of capacitor C20 and inductor L20D included in the area AR21 are connected in series between the input terminal T10 and the output terminal T20.

[0113] On the other hand, the filter device 200X of Comparative Example 2 corresponds to a configuration in which two LC parallel resonators (that is, bandpass filters) are connected in series between an input terminal T10 and an output terminal T20.

[0114] 16 is a diagram illustrating the filter characteristics of the filter device 200 according to the second embodiment. In FIG. 16, the insertion loss in the filter device 200 (solid line LN30) and the insertion loss in the filter device 200X of the second comparative example (dashed line LN 31 ) is shown.

[0115] In the filter device 200, the band-pass filter on the input terminal side of the filter device 200X of Comparative Example 2 is replaced with a high-pass filter, and therefore the attenuation on the lower frequency side of the pass band is slightly less than that of the filter device 200X. However, because the shunt capacitor is omitted, the loss on the higher frequency side is reduced compared to the filter device 200X, and the pass characteristics are improved. Also in the filter device 200, a ring structure is formed by providing the inductor L12 that connects the two resonators, and therefore the degree of coupling between the resonators can be increased while suppressing an increase in the device size.

[0116] The "resonator RC11A" and the "resonator RC12" in the second embodiment correspond to the "fifth resonator" and the "sixth resonator" in the present disclosure, respectively. The "capacitor C10A," "capacitor C20," and "capacitor C30" in the second embodiment correspond to the "third capacitor" to the "fifth capacitor" in the present disclosure, respectively. The "inductor L10A," "inductor L10B," "inductor L20A," "inductor L20B," and "inductor L12" in the second embodiment correspond to the "sixth inductor" to the "tenth inductor" in the present disclosure, respectively. The "inductor L30" in the second embodiment corresponds to the "common inductor" in the present disclosure. The "connection node N31" in the second embodiment corresponds to the "third node" in the present disclosure.

[0117] [Embodiment 3] In the third embodiment, a configuration will be described in which the resonator RC12 in the filter device 200 of the second embodiment is further configured as a high-pass filter.

[0118] 17 is an equivalent circuit diagram of a filter device 200A according to Embodiment 3. In the filter device 200A, the resonator RC12 in the filter device 200 according to Embodiment 2 is replaced with a resonator RC12A.

[0119] More specifically, capacitor C20 in filter device 200 is deleted, and capacitor C20A is added between inductor L20A and output terminal T20. Capacitor C30 is connected between connection node N31 between capacitor C10A and inductor L10A and connection node N32 between capacitor C20A and inductor L20A. That is, although not shown, when the circuit of FIG. 17 is equivalently transformed as in FIG. 15, it corresponds to a configuration in which two high-pass filters are arranged between input terminal T10 and output terminal T20. Therefore, filter device 200A has slightly less attenuation than filter device 200, but its efficiency is further improved.

[0120] Also in the filter device 200A, as shown in the area AR10, a ring structure is formed by the inductor L12 to which the two resonators are connected, so that the degree of coupling between the resonators can be increased while suppressing an increase in the device size.

[0121] The "resonator RC12A" in the third embodiment corresponds to the "seventh resonator" in the present disclosure. The "capacitor C20A" in the third embodiment corresponds to the "sixth capacitor" in the present disclosure. The "connection node N32" in the third embodiment corresponds to the "fourth node" in the present disclosure.

[0122] [Aspect] (Item 1) A filter device includes a main body, an input terminal, an output terminal, a ground terminal, a first resonator, and a second resonator. The first resonator and the second resonator are disposed in the main body and transmit a signal from the input terminal to the output terminal by electromagnetically coupling with each other. Each of the first resonator and the second resonator includes a first path connected from a first node to the ground terminal via a capacitor, and a second path connected from the first node to the ground terminal without via a capacitor. The second path of the first resonator and the second path of the second resonator have a portion in common. The filter device further includes a third path connected to the first node of the first resonator and the first node of the second resonator.

[0123] (Item 2) In the filter device according to item 1, the second path of the first resonator, the second path of the second resonator, and the third path form a ring structure.

[0124] (Item 3) In the filter device according to item 2, the main body has a structure in which a plurality of dielectric layers are laminated, and the annular structure is formed in the same layer of the main body.

[0125] (4) The filter device according to claim 3 further includes a ground electrode connected to the ground terminal and a common via connected to the ground electrode. The first resonator includes a first capacitor electrode arranged opposite the ground electrode, a first via connected to the first capacitor electrode, and a first plate electrode connected to the first via and the common via. The second resonator includes a second capacitor electrode arranged opposite the ground electrode, a second via connected to the second capacitor electrode, and a second plate electrode connected to the second via and the common via. The filter device further includes a third plate electrode connected to the first via and the second via.

[0126] (Item 5) In the filter device described in item 4, the first path of the first resonator is formed by the first capacitor electrode and the first via. The second path of the first resonator is formed by the first plate electrode and the common via. The first path of the second resonator is formed by the second capacitor electrode and the second via. The second path of the second resonator is formed by the second plate electrode and the common via. The third path is formed by the third plate electrode.

[0127] (Item 6) In the filter device according to item 2, the main body has a configuration in which a plurality of dielectric layers are stacked, and the annular structure is formed across the plurality of layers of the main body.

[0128] (Item 7) The filter device described in item 6 further includes a ground electrode connected to the ground terminal, a common electrode disposed on a dielectric layer different from the ground electrode, and a common via connected to the ground electrode and the common electrode. The first resonator includes a third capacitor electrode disposed opposite the ground electrode, a third via connected to the third capacitor electrode, a fourth via connected to the common electrode, and a fourth plate electrode connected to the third and fourth vias. The second resonator includes a fourth capacitor electrode disposed opposite the ground electrode, a fifth via connected to the fourth capacitor electrode, a sixth via connected to the common electrode, and a fifth plate electrode connected to the fifth and sixth vias. The filter device further includes a sixth plate electrode connecting the third via and the fifth via.

[0129] (Item 8) In the filter device described in item 7, the third capacitor electrode and the third via constitute a first path of the first resonator. The fourth plate electrode, the third via, the fourth via, the common electrode, and the common via constitute a second path of the first resonator. The fourth capacitor electrode and the fifth via constitute a first path of the second resonator. The fifth plate electrode, the fifth via, the sixth via, the common electrode, and the common via constitute a second path of the second resonator. The sixth plate electrode constitutes a third path.

[0130] (Item 9) The filter device according to any one of items 1 to 8 further includes a third resonator connected to the input terminal and electromagnetically coupled to the first resonator, and a fourth resonator connected to the output terminal and electromagnetically coupled to the second resonator.

[0131] (Item 10) A filter device according to another aspect includes an input terminal, an output terminal, a ground terminal, a first resonator, and a second resonator. The first resonator and the second resonator transmit a signal from the input terminal to the output terminal by electromagnetically coupling with each other. The first resonator includes a first capacitor connected between a first node and the ground terminal, a first inductor having one end connected to the first node, a second inductor connected to the other end of the first inductor, and a common inductor connected between the other end of the second inductor and the ground terminal. The second resonator includes a second capacitor connected between the second node and the ground terminal, a third inductor having one end connected to the second node, and a fourth inductor connected between the other end of the third inductor and the common inductor. The filter device further includes a fifth inductor connected between the other end of the first inductor and the other end of the third inductor.

[0132] (Item 11) The filter device according to any one of items 1 to 10 is a bandpass filter that passes signals in a specific frequency band.

[0133] (Claim 12) A filter device according to another aspect includes a main body, an input terminal, an output terminal, a ground terminal, a fifth resonator, and a sixth resonator. The fifth resonator and the sixth resonator are disposed in the main body and transmit a signal from the input terminal to the output terminal by electromagnetically coupling with each other. The fifth resonator includes a third capacitor connected between a third node and the input terminal, a sixth inductor having one end connected to the third node, a seventh inductor connected to the other end of the sixth inductor, and a common inductor connected between the other end of the seventh inductor and the ground terminal. The sixth resonator includes a fourth capacitor connected between the output terminal and the ground terminal, an eighth inductor having one end connected to the output terminal, and a ninth inductor connected between the other end of the eighth inductor and the common inductor. The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor.

[0134] (Item 13) The filter device according to item 12 further includes a fifth capacitor connected to the fifth resonator and the sixth resonator.

[0135] (Claim 14) A filter device according to another aspect includes a main body, an input terminal, an output terminal, a ground terminal, a fifth resonator, and a seventh resonator. The fifth resonator and the seventh resonator are disposed in the main body and transmit signals from the input terminal to the output terminal by electromagnetically coupling with each other. The fifth resonator includes a third capacitor connected between a third node and the input terminal, a sixth inductor having one end connected to the third node, a seventh inductor connected to the other end of the sixth inductor, and a common inductor connected between the other end of the seventh inductor and the ground terminal. The seventh resonator includes a sixth capacitor connected between a fourth node and the output terminal, an eighth inductor having one end connected to the fourth node, and a ninth inductor connected between the other end of the eighth inductor and the common inductor. The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor.

[0136] (Item 15) The filter device according to item 14 further includes a fifth capacitor connected to the fifth resonator and the seventh resonator.

[0137] (16th Item) A high-frequency front-end circuit comprising the filter device according to any one of the first to fifteenth items.

[0138] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0139] 10 communication device, 12 antenna, 20 high frequency front end circuit, 22, 28 band pass filter, 24 amplifier, 26 attenuator, 30 mixer, 32 local oscillator, 40 D / A converter, 50 RF circuit, 100, 100A to 100C, 100X, 200, 200A, 200X filter device, 110 main body, 111 top surface, 112 bottom surface, C1 to C4, C10, C10A, C12, C14, C20, C20A, C23, C30, C34 capacitor, DM direction mark, GND Ground terminals: L1, L2A, L2B, L3A, L3B, L4, L5, L10, L10A to L10D, L12, L12A, L20, L20A to L20D, L23A, L23B, L30, L30C Inductors: LY1 to LY10 Dielectric layers: N1A to N4A, N2B, N3B, N10, N20, N31 to N34 Connection nodes: P23, PL10A, PL10B, PL11B, PL11A, PL20, PL20C, PL23, PL23A to PL23D, PL23X, PL30, PL30C, PL40A, PL40B, PL41A, PL41B, PL50, PL50A to PL50C Plate electrodes, PC1, PC2A, PC2B, PC3A, PC3B, PC4, PC14, PC23 capacitor electrodes, PG, PG1, PG2 ground electrodes, RC1 to RC4, RC11, RC11A, RC12, RC12A resonators, T1, T10 input terminals, T2, T20 output terminals, V10 to V12, V20, V20A, V20B, V30, V30A, V40 to V42, VG1 to VG6, VG1A, VG1B, VG2A, VL20, VL30 vias.

Claims

1. 1. A filter device, comprising: The main body and An input terminal, An output terminal; A ground terminal; a first resonator and a second resonator disposed on the main body, the first resonator and the second resonator electromagnetically coupled to each other to transmit a signal from the input terminal to the output terminal; The first resonator is a first capacitor connected between a first node and the ground terminal; a first inductor having one end connected to the first node; a second inductor connected to the other end of the first inductor; a common inductor connected between the other end of the second inductor and the ground terminal, The second resonator is a second capacitor connected between a second node and the ground terminal; a third inductor having one end connected to the second node; a fourth inductor connected between the other end of the third inductor and the common inductor, The filter device further includes a fifth inductor connected between the other end of the first inductor and the other end of the third inductor.

2. The filter device according to claim 1 , wherein the second inductor, the fourth inductor, and the fifth inductor form a ring structure.

3. The main body has a configuration in which a plurality of dielectric layers are laminated, The filter device of claim 2 , wherein the annular structures are formed in the same layer of the body.

4. The filter device comprises: a ground electrode connected to the ground terminal; a common via connected to the ground electrode; The first resonator is a first capacitor electrode disposed opposite the ground electrode; a first via connected to the first capacitor electrode; a first plate electrode connected to the first via and the common via; The second resonator is a second capacitor electrode disposed opposite the ground electrode; a second via connected to the second capacitor electrode; a second plate electrode connected to the second via and the common via; The filter device according to claim 3 , further comprising a third plate electrode connected to the first via and the second via.

5. a path extending from the first inductor to the ground terminal via the first capacitor is formed by the first capacitor electrode and the first via; a path extending from the second inductor to the ground terminal via the common inductor is formed by the first plate electrode and the common via; a path extending from the third inductor to the ground terminal via the second capacitor is formed by the second capacitor electrode and the second via; a path extending from the fourth inductor to the ground terminal via the common inductor is formed by the second plate electrode and the common via; The filter device according to claim 4 , wherein the third plate electrode forms the fifth inductor.

6. The main body has a configuration in which a plurality of dielectric layers are laminated, The filter device of claim 2 , wherein the annular structure is formed across multiple layers of the body.

7. The filter device comprises: a ground electrode connected to the ground terminal; a common electrode disposed on a dielectric layer different from the ground electrode; a common via connected to the ground electrode and the common electrode; The first resonator is a third capacitor electrode disposed opposite the ground electrode; a third via connected to the third capacitor electrode; a fourth via connected to the common electrode; a fourth plate electrode connected to the third via and the fourth via; The second resonator is a fourth capacitor electrode disposed opposite the ground electrode; a fifth via connected to the fourth capacitor electrode; a sixth via connected to the common electrode; a fifth plate electrode connected to the fifth via and the sixth via; The filter device according to claim 6 , further comprising a sixth plate electrode connecting the third via and the fifth via.

8. a path extending from the first inductor to the ground terminal via the first capacitor is formed by the third capacitor electrode and the third via; a path extending from the second inductor to the ground terminal via the common inductor is formed by the fourth plate electrode, the third via, the fourth via, the common electrode, and the common via; a path extending from the third inductor to the ground terminal via the second capacitor is formed by the fourth capacitor electrode and the fifth via; a path extending from the fourth inductor to the ground terminal via the common inductor is formed by the fifth plate electrode, the fifth via, the sixth via, the common electrode, and the common via; The filter device according to claim 7 , wherein the sixth plate electrode forms the fifth inductor.

9. a third resonator connected to the input terminal and electromagnetically coupled to the first resonator; 9. The filter device according to claim 1, further comprising a fourth resonator connected to the output terminal and electromagnetically coupled to the second resonator.

10. 2. The filter device according to claim 1, wherein the filter device is a band-pass filter that passes signals in a specific frequency band.

11. 1. A filter device, comprising: The main body and An input terminal, An output terminal; A ground terminal; a fifth resonator and a sixth resonator disposed in the main body and electromagnetically coupled to each other to transmit a signal from the input terminal to the output terminal; The fifth resonator is a third capacitor connected between a third node and the input terminal; a sixth inductor having one end connected to the third node; a seventh inductor connected to the other end of the sixth inductor; a common inductor connected between the other end of the seventh inductor and the ground terminal, The sixth resonator is a fourth capacitor connected between the output terminal and the ground terminal; an eighth inductor having one end connected to the output terminal; a ninth inductor connected between the other end of the eighth inductor and the common inductor, The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor.

12. The filter apparatus of claim 11 , further comprising a fifth capacitor connected to the fifth resonator and the sixth resonator.

13. 1. A filter device, comprising: The main body and An input terminal, An output terminal; A ground terminal; a fifth resonator and a seventh resonator disposed in the main body and electromagnetically coupled to each other to transmit a signal from the input terminal to the output terminal; The fifth resonator is a third capacitor connected between a third node and the input terminal; a sixth inductor having one end connected to the third node; a seventh inductor connected to the other end of the sixth inductor; a common inductor connected between the other end of the seventh inductor and the ground terminal, The seventh resonator is a sixth capacitor connected between the fourth node and the output terminal; an eighth inductor having one end connected to the fourth node; a ninth inductor connected between the other end of the eighth inductor and the common inductor, The filter device further includes a tenth inductor connected between the other end of the sixth inductor and the other end of the eighth inductor.

14. The filter apparatus of claim 13 , further comprising a fifth capacitor connected to the fifth resonator and the seventh resonator.

15. A high-frequency front-end circuit comprising the filter device according to any one of claims 1, 11 and 13.

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