Filter Device

Abstract

A filter device (100) comprises: a dielectric (110); electrodes (PG1, PG2); and resonators (RC1-RC3). The electrodes (PG1, PG2) are disposed opposing each other in the dielectric, and are connected to a grounding terminal (GND). The resonator (RC1) and the resonator (RC2) are disposed between the electrodes (PG1, PG2). The resonator (RC1) is connected to an input terminal (T1), and the resonator (RC2) is connected to an output terminal (T2). The resonator (RC3) is disposed between the resonators (RC1, RC2). The resonator (RC1) includes a plate conductor (PL1) which is connected at one end to the input terminal and connected at the other end to the grounding terminal. The resonator (RC2) includes a plate conductor (PL2) which is connected at one end to the output terminal and connected at the other end to the grounding terminal. The plate conductors (PL1, PL2) extend in an X-axis direction in the dielectric. The resonators (RC1-RC3) are arranged in a Y-axis direction. The resonator (RC3) includes a capacitor electrode (PC3) disposed opposing the electrode (PG2), and an inductor via (V30) connected to the capacitor electrode (PC3) and the electrode (PG1). The inductor via (V30) extends in a Z-axis direction.

Description

[Technical field]

[0001] The present disclosure relates to a filter device, and more particularly to a technique for improving characteristics in a filter device. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2018-125804 (Patent Document 1) discloses a bandpass filter having multiple resonators arranged between shield electrodes in a dielectric body. Each of the multiple resonators is made of a flat conductor with one end connected to the shield electrode through a via and the other end open, and adjacent resonators are electromagnetically coupled to each other to function as a bandpass filter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-125804 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the bandpass filter disclosed in JP 2018-125804 A (Patent Document 1), the flat conductors that make up the resonators are arranged on the same plane within the dielectric. Therefore, although the magnetic fields generated by adjacent resonators have different directions, the generated magnetic fields may affect each other, which may result in a decrease in the attenuation characteristics of the filter.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to improve the characteristics of a filter device including a plurality of resonators. [Means for solving the problem]

[0006] The filter device according to the present disclosure includes a dielectric, an input terminal, an output terminal, a ground terminal, flat-plate-shaped first and second electrodes, and a first to third resonator. The first and second electrodes are arranged opposite each other on the dielectric and connected to the ground terminal. The first and second resonators are arranged between the first and second electrodes. The first resonator is connected to the input terminal, and the second resonator is connected to the output terminal. The third resonator is arranged between the first and second resonators on the dielectric. The first resonator includes a first flat-plate conductor having one end connected to the input terminal and the other end connected to the ground terminal. The second resonator includes a second flat-plate conductor having one end connected to the output terminal and the other end connected to the ground terminal. Each of the first and second flat-plate conductors extends in a first direction on the dielectric. The first, second, and third resonators are arranged in a second direction intersecting the first direction. The third resonator includes a capacitor electrode disposed opposite the second electrode and an inductor via connected to the capacitor electrode and the first electrode, the inductor via extending in a third direction from the first electrode toward the second electrode. Effect of the Invention

[0007] The filter device according to the present disclosure includes first to third resonators arranged between shield electrodes (first electrode, second electrode). The first and second resonators connected to the input and output terminals, respectively, are resonators made of flat conductors extending in a first direction (X-axis direction), and the third resonator arranged between the two resonators has an inductor via extending in a third direction (Z-axis direction). Therefore, the directions of the magnetic fields generated in the first resonator and the third resonator, and the directions of the magnetic fields generated in the second resonator and the third resonator are in a twisted relationship, so that the influence of the magnetic fields between the resonators is suppressed. This can improve the characteristics of the filter device. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram of a high-frequency front-end circuit in which a filter device according to a first embodiment is mounted. [Diagram 2] 1 is a perspective view showing the inside of a filter device according to a first embodiment. [Diagram 3] 1 is a plan view showing the inside of a filter device according to a first embodiment. [Figure 4] FIG. 11 is a plan view showing the inside of a filter device of a comparative example. [Diagram 5] 5A and 5B are diagrams for explaining the directions of magnetic fields generated in the resonators in the filter devices of the first embodiment and the comparative example. [Figure 6] FIG. 11 is a plan view showing the inside of a filter device according to a first modified example. [Figure 7] 10 is a diagram for explaining the magnetic field direction of a resonator in a filter device according to a first modification. FIG. [Figure 8] 11 is a plan view showing the inside of a filter device according to a second modified example. FIG. [Figure 9] 13 is a diagram for explaining the magnetic field direction of a resonator in a filter device according to Modification 2. FIG. [Figure 10] 13 is a plan view showing the inside of a filter device according to a third modified example. FIG. [Figure 11] 13 is a diagram for explaining the magnetic field direction of a resonator in a filter device according to a third modification. FIG. [Figure 12] FIG. 11 is a plan view showing the inside of a filter device according to a second embodiment. [Figure 13] FIG. 11 is a plan view showing the inside of a filter device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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.

[0010] [Embodiment 1] (Basic configuration of communication device) 1 is a block diagram of a communication device 10 having a high-frequency front-end circuit 20 to which a filter device according to an embodiment 1 is applied. The communication device 10 is, for example, a mobile phone base station.

[0011] 1, a communication device 10 includes an antenna 12, a high-frequency front-end circuit 20, a mixer 30, a local oscillator 32, a digital-to-analog 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. Note that, although 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 will be described with reference to FIG. 1, the high-frequency front-end circuit 20 may also include a reception circuit that receives a high-frequency signal via the antenna 12.

[0012] The communication device 10 up-converts a transmission signal transmitted from the RF circuit 50 into a high-frequency signal and radiates the signal from the antenna 12. The modulated digital signal, which is the transmission signal output from the RF circuit 50, is converted into an analog signal by the D / A converter 40. The mixer 30 mixes the transmission signal, which has been converted from a digital signal to an analog signal by the D / A converter 40, with an oscillation signal from the local oscillator 32, and up-converts the signal into a high-frequency signal. The bandpass filter 28 removes unnecessary waves generated by the up-conversion and extracts only the transmission signal in a desired frequency band. The attenuator 26 adjusts the intensity of the transmission signal. The amplifier 24 amplifies the power of the transmission signal that has passed through the attenuator 26 to a predetermined level. The bandpass filter 22 removes unnecessary waves generated during the amplification process and passes only signal components in a frequency band defined by the communication standard. The transmission signal that has passed through the bandpass filter 22 is radiated from the antenna 12.

[0013] As the bandpass filters 22, 28 in the communication device 10 as described above, a filter device according to the present disclosure can be adopted.

[0014] (Configuration of filter device) Next, a detailed configuration of filter device 100 according to the first embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 and Fig. 3 are a perspective view and a plan view showing the inside of filter device 100, respectively.

[0015] 2 and 3, the filter device 100 includes a rectangular or substantially rectangular parallelepiped dielectric 110 in which a plurality of dielectric layers are stacked in a stacking direction. Each dielectric layer of the dielectric 110 is made of, for example, ceramic. Inside the dielectric 110, inductors and capacitors are formed by a plurality of wiring patterns and electrodes provided on each dielectric layer, and a plurality of vias provided between the dielectric layers. These inductors and capacitors form an LC resonant circuit.

[0016] In the following description, the lamination direction of the dielectric 110 is referred to as the "Z-axis direction", the direction perpendicular to the Z-axis direction and along the short side of the dielectric 110 is referred to as the "X-axis direction", and the direction along the long side of the dielectric 110 is referred to as the "Y-axis direction". In the following, the positive direction of the Z-axis in each figure may be referred to as the upper side, and the negative direction as the lower side. Note that in Figs. 2 and 3, as well as Figs. 4, 6, 8, 10, 12, and 13 described below, the dielectric 110 is omitted, and only the wiring patterns, vias, and terminal conductors formed therein are shown.

[0017] The dielectric 110 has an upper surface 111 and a lower surface 112. An input terminal T1, an output terminal T2, and a ground terminal GND are provided on the lower surface 112 of the dielectric 110. The input terminal T1, the output terminal T2, and the ground terminal GND are external terminals for connecting the filter device 100 to an external device, and are flat-plate-shaped electrodes. Specifically, the input terminal T1, the output terminal T2, and the ground terminal GND are LGA (Land Grid Array) terminals regularly arranged on the lower surface 112 of the dielectric 110.

[0018] A plate electrode PG2 is provided on a dielectric layer adjacent to the lower surface 112 of the dielectric 110. The plate electrode PG2 is connected to a ground terminal GND through a via. Furthermore, a plate electrode PG1 is provided on a dielectric layer adjacent to the upper surface 111 of the dielectric 110. In FIG. 2, the plate electrode PG1 is indicated by a dashed line.

[0019] The plate electrodes PG1 and PG2 are connected by ground vias VG11, VG12, VG21, and VG22 extending in the stacking direction of the dielectric 110. Other ground vias may be further provided to connect the plate electrodes PG1 and PG2.

[0020] The plate electrode PG2 has a substantially H-shape when the dielectric 110 is viewed in a plan view from the Z-axis direction, and the input terminal T1 and the output terminal T2 are disposed in the opening of the plate electrode PG2.

[0021] The filter device 100 of the first embodiment includes five resonators RC1 to RC5 inside the dielectric 110. The resonator RC1 is connected to the input terminal T1, and the resonator RC2 is connected to the output terminal T2. The resonators RC3 to RC5 are disposed between the resonators RC1 and RC2 in the dielectric 110. The resonators RC1 to RC5 are electromagnetically coupled to each other. By adjusting the resonance frequency of each resonator, the filter device 100 functions as a bandpass filter that selectively passes signals in a specific frequency band. A high-frequency signal input to the input terminal T1 propagates through the resonators RC1, RC3, RC5, RC4, and RC2 in this order, and is output from the output terminal T2.

[0022] The resonator RC1 includes a strip-shaped flat conductor PL1 disposed between the flat plate electrodes PG1 and PG2. The flat plate conductor PL1 has an approximately J-shape with a bent portion, and is composed of two conductors along the X-axis direction and a conductor along the Y-axis direction that connects them. One end of the flat plate conductor PL1 is connected to the input terminal T1 through vias V11 and V12 and the flat plate electrode P10. The other end of the flat plate conductor PL1 is connected to the flat plate electrodes PG1 and PG2 through ground vias VG11 and VG12. When the dielectric 110 is viewed from above in the Z-axis direction, the flat plate conductor PL1 partially overlaps with the flat plate electrodes PG1 and PG2. The resonator RC1 functions as a so-called "distributed constant type resonator" due to the capacitance component between the flat plate conductor PL1 and the flat plate electrodes PG1 and PG2, and the inductance component of the flat plate conductor PL1.

[0023] The resonator RC2 includes a strip-shaped flat conductor PL2 disposed between the flat plate electrodes PG1 and PG2. The flat plate conductor PL2 has an approximately J-shape with a bent portion, and is composed of two conductors along the X-axis direction and a conductor along the Y-axis direction that connects them. One end of the flat plate conductor PL2 is connected to the output terminal T2 through the vias V21 and V22 and the flat plate electrode P20. The other end of the flat plate conductor PL2 is connected to the flat plate electrodes PG1 and PG2 through the ground vias VG21 and VG22. When the dielectric 110 is viewed from the Z-axis direction, the flat plate conductor PL2 partially overlaps with the flat plate electrodes PG1 and PG2, and the resonator RC2 functions as a distributed constant type resonator due to the capacitance component between the flat plate conductor PL2 and the flat plate electrodes PG1 and PG2, and the inductance component of the flat plate conductor PL2.

[0024] The resonator RC3 is disposed adjacent to the resonator RC1 in the positive direction of the Y-axis in the dielectric 110. The resonator RC3 includes a capacitor electrode PC3 and an inductor via V30. The capacitor electrode PC3 is a substantially rectangular plate electrode extending in the X-axis direction. When the dielectric 110 is viewed in a plan view from the Z-axis direction, at least a portion of the capacitor electrode PC3 is disposed so as to overlap with the plate electrode PG2. The capacitor electrode PC3 and the plate electrode PG2 form a capacitor. The inductor via V30 is connected between the capacitor electrode PC3 and the plate electrode PG1. That is, the resonator RC3 functions as a so-called "λ / 4 type resonator" in which an inductor and a capacitor are connected in series between the plate electrodes PG1 and PG2.

[0025] The resonator RC4 is disposed adjacent to the resonator RC2 in the negative direction of the Y axis in the dielectric 110. In other words, the resonator RC4 is disposed adjacent to the resonator RC2 in the negative direction of the Y axis. RC3The resonator RC4 includes a capacitor electrode PC4 and an inductor via V40. The capacitor electrode PC4 is a substantially rectangular plate electrode extending in the X-axis direction. When the dielectric 110 is viewed in a plan view from the Z-axis direction, at least a portion of the capacitor electrode PC4 is arranged to overlap with the plate electrode PG2. The capacitor electrode PC5 and the plate electrode PG2 form a capacitor. The inductor via V40 is connected between the capacitor electrode PC4 and the plate electrode PG1. That is, the resonator RC4 functions as a λ / 4 resonator in which an inductor and a capacitor are connected in series between the plate electrodes PG1 and PG2.

[0026] The resonator RC5 is a λ / 4 type resonator in which an inductor and a capacitor are connected in series between the plate electrodes PG1 and PG2, similar to the resonators RC3 and RC4. The resonator RC5 includes a capacitor electrode PC5 and inductor vias V51 and V52. The capacitor electrode PC5 is a substantially rectangular plate electrode extending in the Y-axis direction. The capacitor electrode PC5 is disposed in the dielectric 110 in a region in the negative direction of the X-axis more than the resonators RC3 and RC4 and is spaced apart from the resonators RC3 and RC4. The capacitor electrode PC5 and the plate electrode PG2 form a capacitor. The inductor vias V51 and V52 are connected to the capacitor electrode PC5 and the plate electrode PG1.

[0027] The capacitor electrodes PC3 to PC5 of the resonators RC3 to RC5 are disposed on the same plane inside the dielectric 110 and are capacitively coupled to each other. The flat conductors PL1 and PL2 of the resonators RC1 and RC2 may be disposed on the same plane in the dielectric 110 as the capacitor electrodes PC3 to PC5 of the resonators RC3 to RC5, or may be disposed on a different plane.

[0028] The filter device 100 further includes plate electrodes PC13, PC24, and PC12 for adjusting coupling between the resonators. The plate electrodes PC13 and PC24 are strip-shaped electrodes having a substantially L-shape, and the plate electrode PC12 is a strip-shaped electrode extending in the Y-axis direction.

[0029] When the dielectric 110 is viewed in a plan view from the Z-axis direction, one end of the plate electrode PC13 is connected to the plate conductor PL1 of the resonator RC1 through the via V12, and is disposed so as to partially overlap the capacitor electrode PC3 of the resonator RC3. The plate electrode PC13 adjusts the degree of capacitive coupling between the resonators RC1 and RC3.

[0030] When the dielectric 110 is viewed in a plan view from the Z-axis direction, one end of the plate electrode PC24 is connected to the plate conductor PL2 of the resonator RC2 through the via V22, and is disposed so as to partially overlap the capacitor electrode PC4 of the resonator RC4. The plate electrode PC24 adjusts the degree of capacitive coupling between the resonators RC2 and RC4.

[0031] The plate electrode PC12 is disposed so as to partially overlap the plate electrodes PC13 and PC24 when the dielectric 110 is viewed in a plan view from the Z-axis direction. The plate electrode PC12 adjusts the degree of capacitive coupling between the resonators RC1 and RC2.

[0032] In such a filter device 100, the impedance of the resonators RC1 and RC2 connected to the external device tends to be low as the resonators are made smaller and lower in height, and it may be difficult to ensure a wide passband width. Therefore, it is desirable to make the impedance as high as possible. To achieve this, in the filter device 100, the resonators RC1 and RC2 connected to the input / output terminals are not configured to use capacitor electrodes like the resonators RC3 to RC5, but are configured only with the parasitic capacitance of the band-shaped flat conductor. Naturally, the parasitic capacitance of the flat conductor has a smaller capacitance than the capacitor electrodes like the resonators RC3 to RC5, so that the resonant frequency can be adjusted to a desired resonant frequency while maintaining the impedance of the resonator high by increasing the line length of the flat conductor to increase the inductance component. Specifically, in the resonators RC1 and RC2, the resonant frequency is adjusted by adjusting the positions of the bent parts of the flat conductors PL1 and PL2.

[0033] In the resonators RC3 to RC5, inductance components are obtained by the inductor vias V30, V40, V51, and V52, but the dimension in the Z-axis direction of the dielectric 110 through which the inductor vias extend is shorter than the dimensions in the X-axis and Y-axis directions. Therefore, in order to achieve a desired resonant frequency, it is necessary to increase the capacitance component. Therefore, a relatively large area is required for the capacitor electrodes PC3 to PC5 in the resonators RC3 to RC5.

[0034] In the resonators RC1 and RC2, the capacitance component is obtained by the parasitic capacitance of the flat conductors PL1 and PL2 as described above, and the desired resonance frequency is realized by increasing the line length of the flat conductors PL1 and PL2 to increase the inductance component. Therefore, the area required for the resonators RC1 and RC2 in the dielectric 110 is smaller than that in the case where a capacitor electrode is used, which contributes to miniaturization of the entire size of the filter device 100.

[0035] In the filter device 100, the main current path in the resonators RC1 and RC2 is along the X-axis, which is the extension direction of the flat conductor, and the main current path in the resonators RC3 to RC5 is along the Z-axis, which is the extension direction of the inductor via. That is, the current paths between the resonator RC1 and the resonators RC3 to RC5 and between the resonator RC2 and the resonators RC3 to RC5 are in a twisted relationship, so that the directions of the generated magnetic fields are also in a twisted relationship. Therefore, the magnetic coupling between the resonator RC1 and the resonators RC3 to RC5 and the magnetic coupling between the resonator RC2 and the resonators RC3 to RC5 are reduced. In this way, by combining the resonators such that the directions of the generated magnetic fields are in a twisted relationship, it is possible to suppress the deterioration of the attenuation characteristics due to unintended magnetic coupling between the resonators.

[0036] The above features of filter device 100 of the first embodiment will be described in detail using a comparative example. Fig. 4 is a plan view showing the inside of filter device 200 of the comparative example.

[0037] 4, similar to filter device 100 of the first embodiment, filter device 200 includes five resonators RC1A-RC5A inside dielectric 110, and passes a signal of a specific frequency band among the high-frequency signals received at input terminal T1 and outputs the signal from output terminal T2. The high-frequency signal received at input terminal T1 propagates through resonators RC1A, RC3A, RC5A, RC4A, and RC2A in this order, and is output from output terminal T2.

[0038] Each of the resonators RC1A to RC5A is a distributed constant type resonator having one end connected to a ground terminal GND and the other end open. Each of the resonators RC1A, RC2A, and RC5A includes a strip-shaped flat conductor PL11, PL12, and PL15, one end of which is connected to a flat plate electrode P3 arranged along the long side of the dielectric 110 in the negative direction of the X-axis. The flat plate conductors PL11, PL12, and PL15 extend from the flat plate electrode P3 in the positive direction of the X-axis, and the other end is open. The flat plate electrode P3 is connected to flat plate electrodes PG1 and PG2 included in the filter device 100 by a plurality of ground vias VG.

[0039] The resonators RC3A and RC4A each include a strip-shaped plate conductor PL13 and PL14, one end of which is connected to a plate electrode P4 arranged along the long side in the positive direction of the X-axis of the dielectric 110. The plate conductors PL13 and PL14 extend from the plate electrode P4 in the negative direction of the X-axis, and the other ends are open. The plate electrode P4 is connected to the plate electrodes PG1 and PG2 by a plurality of ground vias VG.

[0040] The flat conductors PL11 to PL15 constituting each resonator are disposed on the same plane in the dielectric 110.

[0041] Fig. 5 is a diagram for explaining the direction of a magnetic field generated in each resonator in the filter devices of the first embodiment and the comparative example. Fig. 5 shows the direction of a magnetic field generated in each resonator when viewed from the positive direction of the X-axis in Figs. 3 and 4.

[0042] In the filter device 200 of the comparative example, the flat conductors constituting the resonators are arranged on the same plane. The flat conductors PL11, PL12, and PL15 and the flat conductors PL13 and PL14 extend in opposite directions from the ground end, so the directions of the magnetic fields generated by the conductors are opposite. However, since the flat conductors are arranged on the same plane and the direction of the current flowing through the conductors is the same in the X-axis direction, a certain amount of magnetic coupling may occur between the flat conductors. This magnetic coupling between the conductors may cause a part of the signal components in the non-pass band to propagate from the input terminal T1 to the output terminal T2, which may reduce the attenuation characteristics in the non-pass band.

[0043] On the other hand, in the case of the filter device 100 of the first embodiment, the direction of the current flowing through the flat conductors PL1 and PL2 in the resonator RC1 connected to the input terminal T1 and the resonator RC2 connected to the output terminal T2 is the X-axis direction, and the direction of the current flowing through the inductor vias V30, V40, V51, and V52 of the resonators RC3 to RC5 is the Z-axis direction, so that the direction of the magnetic field generated in the resonators RC1 and RC2 and the direction of the magnetic field generated in the resonators RC3 to RC5 are in a twisted relationship with each other. Therefore, the magnetic coupling at least between the resonators RC1 and RC3 and between the resonators RC2 and RC4 is suppressed, and as a result, the propagation of signals in the non-pass band associated with the magnetic coupling can be reduced. Therefore, in the filter device 100 of the first embodiment, the attenuation characteristics in the non-pass band can be improved compared to the configuration of the filter device 200 of the comparative example.

[0044] The "plate electrode PG1" and the "plate electrode PG2" in the first embodiment correspond to the "first electrode" and the "second electrode" in the present disclosure, respectively. The "resonators RC1 to RC5" in the first embodiment correspond to the "first resonator" to the "fifth resonator" in the present disclosure, respectively. The "plate conductor PL1" and the "plate conductor PL2" in the first embodiment correspond to the "first plate conductor" and the "second plate conductor" in the present disclosure, respectively. The "capacitor electrode PC3" to the "capacitor electrode PC5" in the first embodiment correspond to the "first capacitor electrode" to the "third capacitor electrode" in the present disclosure, respectively. The "inductor via V30", "inductor via V40", and "inductor vias V51, V52" in the first embodiment correspond to the "first inductor via" to the "third inductor via" in the present disclosure, respectively. The "X-axis direction", "Y-axis direction", and "Z-axis direction" in the first embodiment correspond to the "first direction", "second direction", and "third direction" in this disclosure, respectively.

[0045] (Variation 1) In the filter device 100 of the first embodiment, an example has been described in which the resonators RC1 and RC2 connected to the input / output terminals are configured as distributed constant type resonators, and all of the resonators RC3 to RC5 arranged between the resonators RC1 and RC2 are configured as λ / 4 type resonators. However, similar effects can be achieved with other configurations as long as the distributed constant type resonators and λ / 4 type resonators are mixed in the signal propagation path from the input terminal to the output terminal.

[0046] Fig. 6 is a plan view showing the inside of a filter device 100B of Modification 1. In filter device 100B, resonator RC5 in filter device 100 of Embodiment 1 is replaced with a resonator RC5B. In filter device 100B of Fig. 6, description of elements common to filter device 100 will not be repeated.

[0047] 6, the resonator RC5B is configured as a distributed constant type resonator with one end connected to a ground terminal and the other end open, similar to each resonator in the comparative example of FIG. 4. Specifically, the resonator RC5B includes a band-shaped flat plate conductor PL15B extending in the X-axis direction. The end of the flat plate conductor PL15B in the negative direction of the X-axis is connected to a flat plate electrode P5 extending in the Y-axis direction. The flat plate electrode P5 is connected to the flat plate electrodes PG1 and PG2 by a plurality of ground vias VG. The end of the flat plate conductor PL15B in the positive direction of the X-axis is open.

[0048] The flat conductor PL15B extends between the resonators RC3 and RC4, and the resonator RC5B is electromagnetically coupled to the resonators RC3 and RC4. A high-frequency signal received at the input terminal T1 propagates through the resonators RC1, RC3, RC5B, RC4, and RC2 in this order, and is output from the output terminal T2.

[0049] 7 is a diagram for explaining the magnetic field directions of the resonators in the filter device 100B of the first modification. As shown in FIG. 7, in the filter device 100B, the distributed constant type resonators RC1, RC5B, and RC2 and the λ / 4 type resonators RC3 and RC4 are alternately arranged in the signal path from the input terminal T1 to the output terminal T2. Therefore, the magnetic coupling between the resonator RC3 and the resonators RC1 and RC5B, and between the resonator RC4 and the resonators RC2 and RC5B is suppressed. Therefore, the attenuation characteristics in the non-pass band can be improved.

[0050] The "flat plate conductor PL15B" in the first modification corresponds to the "third flat plate conductor" in the present disclosure.

[0051] (Variation 2) In the second modification, an example of a different arrangement of distributed constant type resonators such as the resonator RC5B in the first modification will be described.

[0052] Fig. 8 is a plan view showing the inside of a filter device 100C of Modification 2. In filter device 100C, resonator RC5B in filter device 100B of Modification 1 is replaced with a resonator RC5C. In filter device 100C of Fig. 8, description of elements common to filter device 100B will not be repeated.

[0053] 8, the resonator RC5C in the filter device 100C includes a band-shaped flat plate conductor PL15C extending in the X-axis direction. An end of the flat plate conductor PL15C in the negative direction of the X-axis is connected to the flat plate electrode P5. An end of the flat plate conductor PL15C in the positive direction of the X-axis is open. The flat plate conductor PL15C extends between the resonators RC1 and RC3, and the resonator RC5C is electromagnetically coupled to the resonators RC1 and RC3. A high-frequency signal received at the input terminal T1 propagates through the resonators RC1, RC5C, RC3, RC4, and RC2 in this order, and is output from the output terminal T2.

[0054] Figure 9 shows Variation 29 is a diagram for explaining the magnetic field directions of the resonators in the filter device 100C. As shown in Fig. 9, in the filter device 100C, the directions of the magnetic fields generated between the resonators RC5C and RC3 and between the resonators RC4 and RC2 are in a twisted relationship, so that the magnetic coupling between the resonators can be suppressed. Therefore, the attenuation characteristics in the non-pass band can be improved.

[0055] The "flat plate conductor PL15C" in the second modification corresponds to the "fourth flat plate conductor" in the present disclosure.

[0056] (Variation 3) In the third modification, another example of a different arrangement of distributed constant resonators such as the resonator RC5B in the first modification will be described.

[0057] Fig. 10 is a plan view showing the inside of a filter device 100D of Modification 3. In filter device 100D, resonator RC5B in filter device 100B of Modification 1 is replaced with a resonator RC5D. In filter device 100D of Fig. 10, description of elements common to filter device 100B will not be repeated.

[0058] 10, the resonator RC5D in the filter device 100D includes a band-shaped flat plate conductor PL15D extending in the X-axis direction. An end of the flat plate conductor PL15D in the negative direction of the X-axis is connected to the flat plate electrode P5. An end of the flat plate conductor PL15D in the positive direction of the X-axis is open. The flat plate conductor PL15D extends between the resonators RC2 and RC4, and the resonator RC5D is electromagnetically coupled to the resonators RC2 and RC4. A high-frequency signal received at the input terminal T1 propagates through the resonators RC1, RC3, RC4, RC5D, and RC2 in this order, and is output from the output terminal T2.

[0059] Figure 11 shows Variation 311 is a diagram for explaining the magnetic field directions of the resonators in the filter device 100D. As shown in Fig. 11, in the filter device 100D, the directions of the magnetic fields generated between the resonators RC1 and RC3 and between the resonators RC4 and RC5D are in a twisted relationship, so that the magnetic coupling between the resonators can be suppressed. Therefore, the attenuation characteristics in the non-pass band can be improved.

[0060] The "flat plate conductor PL15D" in the third modification corresponds to the "fourth flat plate conductor" in the present disclosure.

[0061] In the above-mentioned modified examples 1 to 3, the case where one of the three resonators arranged between the resonator RC1 and the resonator RC2 is a distributed constant type resonator has been described. However, the configuration may be such that only one of the three resonators is a λ / 4 type resonator and the other two resonators are distributed constant type resonators.

[0062] [Embodiment 2] In the filter devices according to the first embodiment and the first to third modifications, the configuration including five resonators has been described, but the number of resonators is not necessarily limited to 5. In the second embodiment, an example in which the filter device is configured with four resonators will be described.

[0063] 12 is a plan view showing the inside of a filter device 100E according to embodiment 2. In the filter device 100E, the resonator RC5 in the filter device 100 of embodiment 1 is deleted. That is, in the filter device 100E, a high-frequency signal received at an input terminal T1 is propagated in this order through the resonators RC1, RC3, RC4, and RC2, and is output from an output terminal T2.

[0064] The filter device 100E also has a configuration in which the resonators RC3 and RC4, which are λ / 4 type resonators, are disposed between the resonators RC1 and RC2, which are distributed constant type resonators. Therefore, in the filter device 100E, the resonators RC3 and RC4 are disposed between the resonators RC1 and RC3 and between the resonators RC2 and resonator RC4 The directions of the magnetic fields generated are in a twisted relationship between the filter device 100E and the non-pass band.

[0065] In addition, since the number of attenuation poles can be increased by increasing the number of resonator stages, the attenuation in the non-pass bands and the steepness of attenuation can be improved by adjusting the frequency of the attenuation poles. On the other hand, as the number of resonators through which a signal passes increases, the loss in the pass band increases. In other words, as the number of resonators increases, there is a trade-off between the attenuation characteristics in the non-pass bands and the loss characteristics in the pass band. Therefore, the number of resonators constituting the filter device is appropriately determined according to the required attenuation characteristics and insertion loss.

[0066] [Embodiment 3] In the third embodiment, a case will be described in which a filter device is configured with three resonators.

[0067] 13 is a plan view showing the inside of a filter device 100F according to embodiment 3. The filter device 100F has a configuration in which the resonator RC4 is further removed from the configuration of the filter device 100E of embodiment 2. That is, in the filter device 100F, a high-frequency signal received at an input terminal T1 propagates through the resonators RC1, RC3, and RC2 in this order, and is output from an output terminal T2.

[0068] In addition, with the removal of the resonator RC4, the plate electrode PC24 for adjusting the degree of coupling between the resonators RC2 and RC4 is removed, and instead, a plate electrode PC23 for adjusting the degree of coupling between the resonators RC2 and RC3 is added. In this case, the plate electrode PC12 for adjusting the degree of coupling between the resonators RC1 and RC2 is disposed so as to overlap the plate electrodes PC13 and PC23.

[0069] The filter device 100F also has a configuration in which the resonator RC3, which is a λ / 4 type resonator, is disposed between the resonators RC1 and RC2, which are distributed constant type resonators. Therefore, in the filter device 100E, the directions of the magnetic fields generated between the resonators RC1 and RC3 and between the resonators RC2 and RC3 are in a twisted relationship. Therefore, the attenuation characteristics in the non-pass band can be improved in the filter device 100F as well.

[0070] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0071] 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, 100B~100F, 200 filter device, 110 dielectric, 111 upper surface, 112 lower surface, GND ground terminal, P3~P5, P10, P20, PC12, PC13, PC23, PC24, PG1, PG2 plate electrodes, PC3~PC5 capacitor electrodes, PL1, PL2, PL11~PL15, PL15B~PL15D plate conductors, RC1~RC5, RC1A~RC4A, RC5A~RC5D resonator, T1 input terminal, T2 output terminal, V11, V12, V21, V22 Vias, V30,V40,V51,V52 inductor vias, VG,VG11,VG12,VG21,VG22 ground vias.

Claims

1. A dielectric material; an input terminal, an output terminal and a ground terminal provided on the dielectric; a first electrode and a second electrode each having a flat plate shape, the first electrode and the second electrode being disposed opposite each other in the dielectric and connected to the ground terminal; a first resonator connected to the input terminal; a second resonator connected to the output terminal; a third resonator disposed in the dielectric between the first resonator and the second resonator; a fourth resonator disposed in the dielectric between the second resonator and the third resonator; a fifth resonator in the dielectric body, the fifth resonator being magnetically coupled to the third resonator and the fourth resonator; the first resonator includes a first flat conductor having one end connected to the input terminal and the other end connected to the ground terminal; the second resonator includes a second flat conductor having one end connected to the output terminal and the other end connected to the ground terminal; Each of the first flat conductor and the second flat conductor extends in a first direction in the dielectric, the first resonator, the second resonator, and the third resonator are arranged in a second direction intersecting the first direction, The third resonator is a first capacitor electrode disposed opposite the second electrode; a first inductor via connected to the first capacitor electrode and the first electrode and extending in a third direction from the first electrode to the second electrode; The fourth resonator is a second capacitor electrode disposed opposite the second electrode; a second inductor via connected to the second capacitor electrode and the first electrode and extending in the third direction; The fifth resonator is a third capacitor electrode disposed opposite the second electrode; a third inductor via connected to the third capacitor electrode and the first electrode and extending in the third direction; A filter device, wherein the third capacitor electrode has a rectangular shape extending in the second direction and is disposed at a position spaced apart in the first direction from the first capacitor electrode and the second capacitor electrode.

2. A dielectric material, an input terminal, an output terminal and a ground terminal provided on the dielectric; a first electrode and a second electrode each having a flat plate shape, the first electrode and the second electrode being disposed opposite each other in the dielectric and connected to the ground terminal; a first resonator connected to the input terminal; a second resonator connected to the output terminal; a third resonator disposed in the dielectric between the first resonator and the second resonator; a fourth resonator disposed in the dielectric between the second resonator and the third resonator; a fifth resonator in the dielectric body, the fifth resonator being magnetically coupled to the third resonator and the fourth resonator; the first resonator includes a first flat conductor having one end connected to the input terminal and the other end connected to the ground terminal; the second resonator includes a second flat conductor having one end connected to the output terminal and the other end connected to the ground terminal; Each of the first flat conductor and the second flat conductor extends in a first direction in the dielectric, the first resonator, the second resonator, and the third resonator are arranged in a second direction intersecting the first direction, The third resonator is a first capacitor electrode disposed opposite the second electrode; a first inductor via connected to the first capacitor electrode and the first electrode and extending in a third direction from the first electrode to the second electrode; The fourth resonator is a second capacitor electrode disposed opposite the second electrode; a second inductor via connected to the second capacitor electrode and the first electrode and extending in the third direction; the fifth resonator includes a fourth flat-plate conductor disposed in the dielectric between the first resonator and the third resonator or between the second resonator and the fourth resonator and extending in the first direction; A filter device, wherein one end of the fourth flat conductor is connected to the ground terminal and the other end is open.

3. 3. The filter device according to claim 1, wherein each of the first flat conductor and the second flat conductor has a bent portion extending from the first direction toward the second direction.

4. 3. The filter device according to claim 1, wherein the first flat conductor and the second flat conductor are disposed on the same plane in the dielectric.

5. 3. The filter device according to claim 1, wherein the first and second flat-plate conductors and the first capacitor electrode are disposed on different planes in the dielectric.

6. 3. The filter device according to claim 1, wherein each of the first capacitor electrode and the second capacitor electrode has a rectangular shape extending in the first direction.

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