Filter devices and multiplexers

Abstract

This invention relates to a filter device and a multiplexer. The filter device (100) includes an unbalanced terminal (T1), balanced terminals (T2, T3), and resonant circuits (110, 120). The resonant circuit (110) is connected to the unbalanced terminal (T1). The resonant circuit (120) is connected to the balanced terminals (T2, T3) and is electromagnetically coupled to the resonant circuit (110). The resonant circuit (110) includes a resonator (RC11) that connects an inductor (L11) and a capacitor (C11) in parallel between the unbalanced terminal (T1) and a reference potential. The resonant circuit (120) includes a resonator (RC21) having an inductor (L21) connected between the balanced terminals (T2, T3) and capacitors (C21A, C21B) connected in series between the balanced terminals (T2, T3).

Description

Technical Field

[0001] This disclosure relates to filter devices and multiplexers, and more particularly to techniques for miniaturizing stacked filter devices. Background Technology

[0002] Balun filters are used to convert between unbalanced and balanced signals. Balanced signals are a pair of signals with equal amplitude and opposite phases, typically used in differential amplifier circuits within ICs in communication systems. Unbalanced signals, on the other hand, are used to transmit changes in potential relative to ground potential, similar to the input / output signals of microstrip lines or antennas.

[0003] In a balanced filter, a structure is provided that transmits signals by electromagnetically coupling a resonator connected to an unbalanced terminal and a resonator connected to a balanced terminal. Several structures of such balanced filters are disclosed in Japanese Patent Application Publication No. 2012-109949 (Patent Document 1), Japanese Patent Application Publication No. 2007-208395 (Patent Document 2), and Japanese Patent Application Publication No. 2012-120149 (Patent Document 3).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-109949

[0005] Patent Document 2: Japanese Patent Application Publication No. 2007-208395

[0006] Patent Document 3: Japanese Patent Application Publication No. 2012-120149

[0007] The resonators used as balanced filters can be categorized into two types: those with balanced or unbalanced terminals connected to the resonator via an inductor and a reference potential (hereinafter also referred to as "short-circuit resonators"), and those with balanced or unbalanced terminals connected to the reference potential via a capacitor (hereinafter also referred to as "open-type resonators"). When the wavelength of the transmitted signal is set to λ, generally, the line length is set to λ / 4 in short-circuit resonators and λ / 2 in open-type resonators.

[0008] In the balanced filter described in Japanese Patent Application Publication No. 2012-109949 (Patent Document 1), the resonators on both the unbalanced terminal side and the balanced terminal side are formed by short-circuit resonators. On the other hand, in Japanese Patent Application Publication No. 2007-208395 (Patent Document 2) and Japanese Patent Application Publication No. 2012-120149 (Patent Document 3), the resonators on both sides are formed by open-type resonators.

[0009] In open-type resonators, since the required line length is λ / 2 (half a wavelength), a 180° phase difference can be easily achieved, especially when used as a resonator on the balanced terminal side, thus providing the advantage of excellent balance characteristics. Furthermore, open-type resonators are generally known to have a higher Q value than short-circuit resonators, which is beneficial for both passivity and attenuation characteristics.

[0010] On the other hand, in short-circuit resonators, the required line length is shorter than that in open-circuit resonators, which is beneficial for the miniaturization of the overall filter.

[0011] Balanced filters are sometimes used in mobile terminals, such as mobile phones or smartphones. In these communication devices, as communication quality improves, the demand for further miniaturization and thinning increases. Consequently, components such as balanced filters also require miniaturization and lower height. Summary of the Invention

[0012] This disclosure was made to solve the aforementioned problems, with the aim of suppressing the degradation of filter characteristics in balanced filters while achieving miniaturization.

[0013] The filter device disclosed herein includes: an unbalanced terminal, a first balanced terminal and a second balanced terminal, a first resonant circuit and a second resonant circuit. The first resonant circuit is connected to the unbalanced terminal. The second resonant circuit is connected to the first balanced terminal and the second balanced terminal, and is electromagnetically coupled to the first resonant circuit. The first resonant circuit includes a first resonator, which is formed by connecting a first inductor and a first capacitor in parallel between the unbalanced terminal and a reference potential. The second resonant circuit includes a second resonator, which has: a second inductor connected between the first balanced terminal and the second balanced terminal, and a second capacitor and a third capacitor connected in series between the first balanced terminal and the second balanced terminal.

[0014] In the filter device disclosed herein, in the balanced filter that converts signals between unbalanced and balanced lines, the first resonant circuit connected to the unbalanced terminal is formed by a short-circuit resonator whose one end of an inductor is directly connected to a reference potential. On the other hand, the second resonant circuit connected to the balanced terminal is formed by an open-type resonator whose ungrounded inductor is connected between the two balanced terminals. By using an open-type resonator on the balanced line side (output side), good balance characteristics can be obtained. Furthermore, by using a short-circuit resonator outside the output side, miniaturization can be achieved. Therefore, in the balanced filter, the degradation of filter characteristics can be suppressed while miniaturization is achieved. Attached Figure Description

[0015] Figure 1This is a block diagram of a communication device having a front-end circuit that applies the filter device according to Embodiment 1.

[0016] Figure 2 yes Figure 1 The equivalent circuit diagram of the filter device.

[0017] Figure 3 yes Figure 2 A three-dimensional view of the filter device.

[0018] Figure 4 It means in Figure 3 The diagram of the internal structure of the dielectric is omitted.

[0019] Figure 5 yes Figure 3 An exploded perspective view of the filter device.

[0020] Figure 6 This is a diagram used to illustrate the characteristics of the filter device in Embodiment 1.

[0021] Figure 7 This is a diagram showing the internal structure of the filter device in Modified Example 1.

[0022] Figure 8 This is a diagram showing the internal structure of the filter device in Modified Example 2.

[0023] Figure 9 This is a diagram showing the internal structure of the filter device in Modified Example 3.

[0024] Figure 10 This is a diagram showing the internal structure of the filter device in Modified Example 4.

[0025] Figure 11 This is a diagram showing the internal structure of the filter device in the reference example.

[0026] Figure 12 This is a diagram showing the internal structure of the filter device in Modified Example 5.

[0027] Figure 13 This is the equivalent circuit diagram of the filter device in Variation Example 6.

[0028] Figure 14 This is the equivalent circuit diagram of the filter device in variation example 7.

[0029] Figure 15 This is the equivalent circuit diagram of the duplexer according to Embodiment 2.

[0030] Figure 16 yes Figure 15 A three-dimensional view of the duplexer.

[0031] Figure 17 yes Figure 16 An exploded three-dimensional view of a duplexer. Detailed Implementation

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent reference numerals will be used for the same parts in the drawings, and their description will not be repeated.

[0033] [Implementation Method 1]

[0034] (Overview of the communication device)

[0035] Figure 1 This is a block diagram of a communication device 1 having a front-end circuit 10 of a filter device 100 according to embodiment 1. (Refer to...) Figure 1 In addition to the front-end circuit 10, the communication device 1 also has an antenna ANT and an RFIC 20 as a signal processing circuit.

[0036] RFIC20 outputs a high-frequency signal as a transmit signal to the transmit-side line TX. This high-frequency signal is radiated as a radio wave from the antenna ANT via the front-end circuit 10. Additionally, the radio wave received by the antenna ANT is input to RFIC20 as a receive signal, i.e., a high-frequency signal, from the receive-side line RX. RFIC20 processes this receive signal and transmits it to subsequent circuitry.

[0037] In addition to the filter device 100, the front-end circuit 10 also includes a switch SW, filters FLT1 and FLT2, a power amplifier PA, and a low-noise amplifier LNA. The switch SW is used to switch the transmission and reception of radio waves in the antenna ANT. The switch SW includes a common terminal TC and two selection terminals TA and TB. The common terminal TC is connected to the antenna ANT. The selection terminal TA is connected to the transmit-side line TX via filter FLT1 and power amplifier PA. The selection terminal TB is connected to the receive-side line RX via filter FLT2, low-noise amplifier LNA, and filter device 100.

[0038] When the antenna ANT radiates radio waves, the common terminal TC of the switch SW is connected to the selection terminal TA. On the other hand, when the antenna ANT receives radio waves, the common terminal TC of the switch SW is connected to the selection terminal TB.

[0039] The power amplifier PA amplifies the transmitted signal, i.e., the high-frequency signal, from RFIC20 and outputs it to filter FLT1. Filter FLT1 consists of a low-pass filter, a high-pass filter, or a band-pass filter, allowing the desired frequency band of the high-frequency signal amplified by the power amplifier PA to pass through. The high-frequency signal passing through filter FLT1 is then radiated as a radio wave from antenna ANT via switch SW.

[0040] Like filter FLT1, filter FLT2 is composed of a low-pass filter, a high-pass filter, or a band-pass filter, allowing the desired frequency band of the received signal (i.e., the high-frequency signal) received by antenna ANT to pass through. The high-frequency signal passing through filter FLT2 is amplified with low noise by low-noise amplifier LNA and then transmitted to filter device 100.

[0041] Filter device 100 is a balanced filter (balancer) used to convert unbalanced signals into balanced signals. Balanced signals are a pair of signals with equal amplitudes and opposite phases, while unbalanced signals are signals used to transmit changes in potential relative to ground potential. Generally, the lines connected to the antenna are unbalanced lines. On the other hand, in IC circuits such as RFIC 20, balanced signals are used for processing. Therefore, the received signal from the antenna ANT, which is transmitted as an unbalanced signal, is converted into a balanced signal suitable for processing in RFIC 20 using filter device 100.

[0042] (Structure of the filter device)

[0043] Next, use Figures 2-5 A detailed description of the filter device 100 is provided. Figure 2 This is the equivalent circuit diagram of filter device 100. Figure 3 This is a perspective view of the filter device 100. Figure 4 It means that it was omitted. Figure 3 A diagram showing the internal structure of the dielectric in the image. Additionally... Figure 5 This is an exploded perspective view of the filter device 100. Figures 3-5 In this design, the normal direction (stack direction) of the dielectric layer is set as the Z-axis direction, and the plane perpendicular to the Z-axis direction is set as the XY plane. Furthermore, in... Figure 4 And the following Figures 7-12 In the diagram representing the internal structure, the scale of the stacking direction is partially exaggerated.

[0044] Reference Figure 2 The equivalent circuit of the filter device 100 includes: an unbalanced terminal T1 on the input side and balanced terminals T2 and T3 on the output side, a resonant circuit 110 (first resonant circuit) connected to the unbalanced terminal T1, and a resonant circuit 120 (second resonant circuit) connected to the balanced terminals T2 and T3. Each of the resonant circuits 110 and 120 is configured to include at least one LC parallel resonator. Figure 2 In the example, the resonant circuit 110 includes three resonators RC11, RC12, and RC13, and the resonant circuit 120 includes one resonator RC21.

[0045] Resonators RC11, RC12, and RC13 are all LC parallel resonators formed by connecting a capacitor and an inductor in parallel. Resonator RC11 has a capacitor C11 and an inductor L11 connected in parallel, with one connection node connected to a reference potential (ground potential) and the other connection node connected to the unbalanced terminal T1. That is, resonator RC11 has a structure in which a capacitor C11 and an inductor L11 are connected in parallel between the unbalanced terminal T1 and the reference potential.

[0046] The resonator RC12 has a capacitor C12 and an inductor L12 connected in parallel. One connection node is connected to the reference potential (ground potential), and the other connection node is connected to the unbalanced terminal T1 via capacitor C15.

[0047] The resonator RC13 has a capacitor C13 and an inductor L13 connected in parallel, with one connection node connected to a reference potential (ground potential). Furthermore, in the resonator RC13, the other connection node of the capacitor C13 and the inductor L13 is open and not connected anywhere.

[0048] Thus, the resonators included in the resonant circuit 110 are "short-circuit resonators" where the inductor is directly connected to the reference potential. Resonators RC11 and RC12, and resonators RC12 and RC13 are electromagnetically coupled. Additionally, resonators RC11 and RC12 are capacitively coupled through capacitor C15. By adjusting the resonant frequencies of resonators RC11, RC12, and RC13, the resonant circuit 110 functions as a bandpass filter.

[0049] The resonant circuit 120 includes a resonator RC21 with an inductor L21 and capacitors C21A and C21B. Inductor L21 is connected between the balancing terminals T2 and T3. Additionally, capacitors C21A and C21B are connected in series between the balancing terminals T2 and T3. That is, the series-connected capacitors C21A and C21B and the inductor L21 are connected in parallel between the balancing terminals T2 and T3. The connection point between capacitors C21A and C21B is connected to a reference potential.

[0050] In resonator RC21, the balancing terminals T2 and T3 are connected to the reference potential via capacitors C21A and C21B, respectively, while inductor L21 is not directly connected to the reference potential. That is, resonator RC21 is an "open resonator".

[0051] Resonators RC13 and RC21 are electromagnetically coupled, and the signal input to the unbalanced terminal T1 is transmitted to resonator RC21 through this electromagnetic coupling. Since resonator RC21 is symmetrically constructed with respect to the reference potential in the circuits connected to the balanced terminal T2 and the circuits connected to the balanced terminal T3, signals with the same amplitude and phase reversal are output from the balanced terminals T2 and T3.

[0052] Reference Figures 3-5 The filter device 100 includes a dielectric substrate (laminated body) 130 formed by stacking multiple dielectric layers (first layer LY1 to fifth layer LY5), having a generally rectangular parallelepiped shape. Multiple external electrodes (side electrodes) in a generally C-shaped manner are provided on the outer surface of the dielectric substrate 130, extending across the upper surface 131, sides 133-136, and lower surface 132. The external electrodes are used for connection to external devices and also for connection between electrodes disposed in the layers of the dielectric substrate 130. The external electrodes include an unbalanced terminal T1, balanced terminals T2 and T3, and a ground electrode GND (reference potential terminal) for connection to a reference potential. The unbalanced terminal T1 is provided on side 136, and the balanced terminals T2 and T3 are provided on sides 134 and 133, respectively. The ground electrode GND is provided on sides 133, 134, and 135. A directional mark DM indicating direction is affixed to the upper surface 131 of the dielectric substrate 130.

[0053] The unbalanced terminal T1 is connected to the planar electrode C0 disposed on the third layer LY3. The planar electrode C0 is connected to a via V1A extending from the second layer LY2 to the fourth layer LY4 in the stacking direction (Z-axis direction). The via V1A is connected to the wiring electrode LP1 in the second layer LY2 and to the planar electrode C1 in the fourth layer LY4. Figure 4 as well as Figure 5 As shown, the wiring electrode LP1 extends along the Y-axis in the second layer LY2 and is connected to the via V1.

[0054] The via V1 extends from the second layer LY2 to the fifth layer LY5 in the stacking direction, and is connected to the planar electrode CG in the fifth layer LY5. The planar electrode CG is connected to the ground electrode GND formed on the outer surface of the dielectric substrate 130.

[0055] It consists of vias V1 and V1A and wiring electrode LP1. Figure 2 The inductor L11 is located in the middle. Additionally, the planar electrode C1 of the fourth layer LY4 and the planar electrode CG of the fifth layer LY5 are opposite each other, and are composed of planar electrode C1 and planar electrode CG. Figure 2 The capacitor C11 is located within the circuit. Therefore, it is composed of vias V1 and V1A, wiring electrode LP1, and planar electrodes C1 and CG. Figure 2 The resonator RC11 in the middle.

[0056] It consists of a wiring electrode LP2 disposed on the second layer LY2, a via V2A extending from the second layer LY2 to the fourth layer LY4 in the stacking direction, and a via V2 extending from the second layer LY2 to the fifth layer LY5 in the stacking direction. Figure 2 The inductor L12 is located in the middle. The planar electrode C2, connected to the via V2A in the fourth layer LY4, is opposite to the planar electrode CG formed in the fifth layer LY5. The structure consists of the planar electrode C2 and the planar electrode CG. Figure 2 The capacitor C12 is composed of vias V2 and V2A, wiring electrode LP2, and planar electrodes C2 and CG. Figure 2 The resonator RC12 is located in the middle. Furthermore, the planar electrode C0 of the third layer LY3, which is connected to the unbalanced terminal T1, is opposite to the planar electrode C2 disposed on the fourth layer LY4, and the structure consists of the planar electrode C0 and the planar electrode C2. Figure 2 Capacitor C15 in the middle.

[0057] It consists of a wiring electrode LP3 disposed on the second layer LY2, a via V3A extending from the second layer LY2 to the fourth layer LY4 in the stacking direction, and a via V3 extending from the second layer LY2 to the fifth layer LY5 in the stacking direction. Figure 2 The inductor L13 is located in the middle. The planar electrode C3, connected to the via V3A in the fourth layer LY4, is opposite to the planar electrode CG located in the fifth layer LY5. The structure consists of the planar electrode C3 and the planar electrode CG. Figure 2 The capacitor C13 is composed of vias V3 and V3A, wiring electrode LP3, and planar electrodes C3 and CG. Figure 2 The resonator RC13 in the middle.

[0058] In the second layer LY2, wiring electrodes LP1, LP2, and LP3 are arranged separately along the X-axis. Furthermore, vias V1 and V1A, vias V2 and V2A, and vias V3 and V3A are spaced at approximately the same interval. Inductors L11, L12, and L13 are wound around the same winding axis along the X-axis and are electromagnetically coupled to each other.

[0059] The resonator RC21 of the resonant circuit 120 is composed of wiring electrode LP4, planar electrodes C4, C5, CG, and vias V4, V5. Wiring electrode LP4 is disposed on the same second layer LY2 as wiring electrodes LP1, LP2, LP3 in the resonant circuit 110. Viewed from above in the stacking direction of the dielectric substrate 130, wiring electrode LP4 has a generally C-shaped form, with the open end of this C-shape facing the resonant circuit 110. In other words, the open end of wiring electrode LP4 is configured to face the negative direction of the X-axis. In the resonator RC21, wiring electrode LP4, used to adjust the difference in line length with the resonator RC13 (which is a short-circuit resonator), has a path extending from the connection point with vias V4, V5 in a direction away from the resonator RC13 (which is a short-circuit resonator). Furthermore, the shape of wiring electrode LP4 is not limited to a generally C-shaped form; it can also be a V-shaped, U-shaped, or zigzag shape.

[0060] Two through holes V4 and V5, extending in the stacking direction to the fourth layer LY4, are respectively connected to the two open ends of the wiring electrode LP4. Through hole V4 is connected to the planar electrode C4 disposed in the fourth layer LY4, and through hole V5 is connected to the planar electrode C5 disposed in the fourth layer LY4. The wiring electrode LP4 and the through holes V4 and V5 constitute the structure. Figure 2 Inductor L21 in the middle.

[0061] Plate electrode C4 is connected to balance terminal T2, and plate electrode C5 is connected to balance terminal T3. Plate electrodes C4 and C5 are opposite to plate electrode CG disposed on the fifth layer LY5. The structure consists of plate electrode C4 and plate electrode CG. Figure 2 The capacitor C21A is included. Additionally, it is composed of plate electrode C5 and plate electrode CG. Figure 2 Capacitor C21B in the middle.

[0062] The spacing between vias V4 and V5 is set to be almost the same as the spacing between vias V3 and V3A of resonator RC13. Inductor L21 is the same as inductors L11, L12, and L13 in resonant circuit 110, wound around a winding axis along the X-axis. Therefore, resonators RC13 and RC21 are electromagnetically coupled, thereby the signal supplied to the unbalanced terminal T1 is transmitted to resonator RC21 via resonators RC11, RC12, and RC13.

[0063] Here, with the wavelength of the signal to be transmitted set to λ, the required line length (i.e., the line length of the inductor) for resonators RC11, RC12, and RC13, which are short-circuit resonators, is λ / 4. On the other hand, the required line length for resonator RC21, which is an open-type resonator, is λ / 2. In each resonator, the lengths of the vias provided in the stacking direction are almost the same, so the difference in line length between resonator RC21 and resonators RC11, RC12, and RC13 is adjusted by the line length of the wiring electrode LP4 provided in the second layer LY2.

[0064] In this way, by using vias in a portion of the inductors of both the short-circuit resonators (RC11, RC12, RC13) and the open-type resonator (RC21), and with the via lengths of the short-circuit resonators and the open-type resonators being approximately the same, even with an open-type resonator structure, the height dimension of the filter device can be suppressed, thus achieving miniaturization of the filter device. Furthermore, by using vias to construct the inductors in each resonator, the Q value can be improved compared to the case where inductors are constructed using printed coils within the dielectric layer, thereby suppressing the degradation of filter characteristics. Moreover, by using an open-type resonator with a line length of λ / 2 for the output-side resonator RC21, the phase difference of the signals output from the balancing terminals T2 and T3 can be easily set to 180°, thus achieving good balance characteristics.

[0065] Figure 6 This is a diagram used to illustrate the characteristics of the filter device 100 in Embodiment 1. Figure 6 In the middle, in the chart on the left ( Figure 6 The insertion loss (IL) and return loss (RL) after the balanced transformation are shown in (a) in the central graph. Figure 6 (b) shows the amplitude balance (AB) of the signals output from the balancing terminals T2 and T3, as shown in the graph on the right. Figure 6 (c) shows the phase difference (PD) of the signals output from the balancing terminals T2 and T3. Furthermore, in Figure 6 In this context, the passband of the filter device 100 is 3.2 GHz to 4.0 GHz.

[0066] Reference Figure 6 In (a), the solid line LN10 represents the insertion loss from the unbalanced terminal T1 to the balanced terminals T2 and T3, the dashed line LN11 represents the reflection loss in the unbalanced terminal T1, and the dotted line LN12 represents the reflection loss under the differential mode of the balanced terminals T2 and T3.

[0067] For insertion loss, it is possible to achieve a value below 3.5 dB within the specified range using the passband. Furthermore, for reflection loss, it is also possible to achieve a value below 10 dB within the specified range using the passband.

[0068] for Figure 6 The amplitude balance of (b) is expressed in dB as the difference between the amplitude of the signal output from the balancing terminal T3 and the amplitude of the signal output from the balancing terminal T2. For example... Figure 6 As shown by the solid line LN20 in (b), the amplitude balance is -0.10dB to 0.32dB in the object passband, achieving within ±1.0dB of the specification range.

[0069] Figure 6 The phase deviation (c) represents the phase difference between the signal output from the balanced terminal T2 and the signal output from the balanced terminal T3. For example... Figure 6 As shown by the solid line LN30 in (c), the phase deviation is -2.0° to -1.3° in the object passband, achieving a specification range within ±10°.

[0070] As described above, in the filter device 100 of Embodiment 1, the desired filter characteristics and balance characteristics are achieved, and the overall device is miniaturized.

[0071] Furthermore, the "resonator RC11" and "resonator RC21" in Embodiment 1 correspond to the "first resonator" and "second resonator" in this disclosure, respectively. The "inductor L11" and "capacitor C11" of resonator RC11 in Embodiment 1 correspond to the "first inductor" and "first capacitor" in this disclosure, respectively. The "inductor L21" of resonator RC21 in Embodiment 1 corresponds to the "second inductor" in this disclosure, and the "capacitor C21A" and "capacitor C21B" correspond to the "second capacitor" and "third capacitor" in this disclosure, respectively. The "via V1" and "via V1A" in Embodiment 1 correspond to the "first conductor" and "second conductor" in this disclosure, respectively. The "via V4" and "via V5" in Embodiment 1 correspond to the "third conductor" and "fourth conductor" in this disclosure, respectively. In Implementation 1, the “wiring electrode LP1” and “wiring electrode LP4” correspond to the “first wiring electrode” and “second wiring electrode” in this disclosure, respectively.

[0072] <Variation Example>

[0073] (Variation Example 1)

[0074] Figure 7This is a diagram showing the internal structure of the filter device 100A in Modified Example 1. In the filter device 100A, the structure is the same as in the filter device 100 of Embodiment 1, except that the wiring electrode LP4 of the inductor L21 constituting the resonant circuit 120 is replaced with the wiring electrode LP4A. In the filter device 100A, elements not repeated in the filter device 100 are described.

[0075] Reference Figure 7 The wiring electrode LP4A in the filter device 100A has a generally C-shaped shape, similar to the wiring electrode LP4 in Embodiment 1, but is configured with its open end facing the opposite direction, with the open end of the wiring electrode LP4A facing the positive direction of the X-axis. In other words, the wiring electrode LP4A has a path extending from the connection point with the vias V4 and V5 toward the resonant circuit 110. Furthermore, with this configuration, the positions of the vias V4 and V5 are changed to a position slightly shifted in the positive direction of the X-axis compared to the filter device 100.

[0076] Furthermore, the shape of the wiring electrode LP4A is not limited to a roughly C-shaped shape; it can also be a V-shaped, U-shaped, or zigzag shape.

[0077] In this way, in a resonant circuit connected to the balance terminal, the plate electrode of an open resonator, which is used to adjust the line length of a short-circuit resonator, can also be extended in a direction close to the short-circuit resonator.

[0078] (Variation Example 2)

[0079] As mentioned above, the line length of an open-type resonator needs to be longer than that of a short-circuit resonator. However, due to limitations in the overall size of the filter device, it may be impossible to ensure the required line length for an open-type resonator.

[0080] In Variation 2, a structure is described that compensates for the insufficient path length by using a short-circuit resonator and capacitive coupling between the open resonator when the required line length for the open resonator cannot be fully guaranteed.

[0081] Figure 8 This is a diagram showing the internal structure of the filter device 100B in Modified Example 2. (Refer to...) Figure 8In filter device 100B, the wiring electrode LP4 of resonator RC21 is replaced with wiring electrode LP4B, and a planar electrode C6 is added opposite to the wiring electrode LP3 of resonator RC13 and the wiring electrode LP4B of resonator RC21. In other words, when viewed from the stacking direction of the laminate, the planar electrode C6 is positioned to overlap with at least a portion of wiring electrode LP3 and at least a portion of wiring electrode LP4B. In filter device 100B, the description of elements not repeated in filter device 100 will not be repeated.

[0082] Reference Figure 8 In the filter device 100B, the wiring electrode LP4B of the resonator RC21 extends in the Y-axis direction in the same way as the wiring electrode LP3 of the resonator RC13, and its line length is almost the same as that of the wiring electrode LP3. In the filter device 100 of Embodiment 1, the line length of the resonator RC21, which is an open-type resonator, is adjusted by the length of the wiring electrode LP4, but... Figure 8 With such a structure, it may not be possible to ensure the required λ / 2 line length for the resonator RC21 as an open-type resonator using only wiring electrodes and vias. This could happen, for example, when the dimensions of the filter device in the X-axis direction are limited.

[0083] In filter device 100B, the wiring electrode LP4B of resonator RC21 and the wiring electrode LP3 of resonator RC13 are coupled to the same length via plate electrode C6, and for insufficient line length, the resonant frequency is adjusted by adjusting the capacitive component between the resonator and the reference potential in resonator RC21. However, if resonators RC13 and RC21 are coupled in this state, especially in areas where the wiring electrode, plate electrode, and via are located are narrow, the magnetic coupling between the resonators may become stronger. In such a case, as... Figure 8 As shown, the magnetic coupling between the resonators is adjusted by adding capacitive coupling between the additional wiring electrode LP4B and the wiring electrode LP3 via the planar electrode C6. Furthermore, it is preferable that the planar electrode C6 is positioned at the center of the line length of the resonator RC21 when adding capacitive coupling between the additional wiring electrodes. Since the current flowing through the center of the line length of the resonator RC21 is zero, the balanced characteristics of the resonator RC21 can be maintained by positioning the planar electrode C6 at this location.

[0084] As mentioned above, by using short-circuit resonators and open-type resonators with capacitive coupling, the line length of the open-type resonator can be shortened, thus enabling further miniaturization of the filter device.

[0085] Furthermore, the "flat plate electrode C6" in Modification 2 corresponds to the "coupled electrode" in this disclosure.

[0086] (Variation Example 3)

[0087] Figure 9 This is a diagram showing the internal structure of the filter device 100C in Modified Example 3. In the filter device 100C, the spacing D2 of the through holes V4 and V5 of the inductor L21 that forms the resonant circuit 120 connected to the balanced terminals T2 and T3 is wider than the spacing D1 of the through holes V3 and V3A of the inductor L13 that forms the resonant circuit 110 connected to the unbalanced terminal T1 (D1 < D2).

[0088] In the electromagnetic coupling of resonators RC13 and RC21, vias V3 and V5 of RC13 and V3A and V4 of RC21 are coupled. Since the spacing D2 of the vias in RC21 is narrower than the spacing D1 of the vias in RC13, it's possible that via V3 of RC13 is also coupled to via V4 of RC21, and via V3A of RC13 is also coupled to via V5 of RC21. The current flowing through via V3 flows in opposite directions to the current flowing through via V4. Therefore, if via V4 is coupled to both via V3 and via V3A, a portion of the transmitted signal will be canceled out, potentially leading to an increase in insertion loss.

[0089] As in the filter device 100C of Modified Example 3, the spacing D2 of the vias of resonator RC21 is wider than the spacing D1 of the vias of resonator RC13, thereby reducing the coupling between vias V4 and V3, and between vias V5 and V3A, thus suppressing the increase in insertion loss. Furthermore, the increased core diameter of inductor L21 increases its inductance, thereby improving the Q value of resonator RC21 and enhancing its throughput characteristics.

[0090] In addition, Figure 9 In this embodiment, the wiring electrode LP4C constituting the inductor L21 is generally V-shaped, but it can also be generally C-shaped, similar to embodiment 1.

[0091] (Variation Example 4)

[0092] In Variation 4, the structure of a filter device capable of supplying DC power to an external device from an open-type resonator connected to a balancing terminal is described.

[0093] Figure 10This diagram shows the internal structure of the filter device 100D in Modified Example 4. In the filter device 100D, a power supply terminal for DC power supply is provided at the center of the line length in the resonator RC21, which is an open-type resonator. More specifically, in the resonator RC21, the lengths of the vias V4 and V5 are equal, therefore a power supply terminal TDF is connected to the center of the wiring electrode LP4D. The power supply terminal TDF is connected to an external power supply electrode (not shown) provided on the outer surface of the dielectric substrate 130. Other devices are connected to this external electrode, thereby supplying DC power to the connected devices.

[0094] In an open-type resonator, the center of the line length (i.e., the center of inductor L21) has a specified potential relative to the reference potential, and is the position where the current flowing through it is zero. Therefore, even if power is supplied from the center of the line length, it will not affect the signals output from the balancing terminals T2 and T3 (i.e., the current output from the balancing terminals T2 and T3).

[0095] Therefore, by providing a power supply terminal at the center of the line length of the open resonator, the filter device can also be used as a DC power source without affecting the characteristics of the filter device.

[0096] In addition, Figure 10 In, with Figure 9 Similarly, in variation 3, the spacing of the vias in the open-type resonator is wider than that in the short-circuit resonator, but it can also be like... Figure 4 as well as Figure 5 As shown in the filter device, the spacing of the vias in the open-type resonator is the same as that in the short-circuit resonator.

[0097] Furthermore, since the current flowing through the center of the line length of an open-type resonator is zero, therefore... Figure 11 As with the filter device 100E of the reference example shown, even if the central part of the line length of the resonator RC21 is connected to the plate electrode CG through the via V6, it will not affect the characteristics of the filter device.

[0098] (Variation Example 5)

[0099] In Embodiment 1 and its variations described above, a structure using a through-hole penetrating the dielectric layer as a conductor for interlayer connection was explained. In Variation 5, a structure using a side electrode provided on the side of the dielectric substrate as a conductor for interlayer connection was explained.

[0100] Figure 12This is a diagram showing the internal structure of the filter device 100F in Modified Example 5. In the filter device 100F, side electrodes provided on the side of the dielectric substrate 130 are used as conductors connecting the wiring electrode LP4D and the plate electrodes C4 and C5 in the resonator RC21 of the resonant circuit 120. More specifically, the balancing terminals T2 and T are used as side electrodes 3.

[0101] As described above, open-type resonators require a longer circuit length than short-circuit resonators. However, by utilizing side electrodes, the spacing between the conductors can be widened, thus extending the circuit length of the open-type resonator (resonator RC21). Furthermore, due to the wider electrode spacing, as explained in Modification 3, coupling between each side electrode and the vias V3 and V3A of the resonator RC13 can be suppressed, thereby reducing insertion loss. Moreover, the increased core diameter of the inductor L21, composed of the wiring electrode LP4D and the side electrodes, increases the inductance of inductor L21. This improves the Q value of resonator RC21, thus enhancing its throughput characteristics.

[0102] In addition, Figure 12 In this example, the conductor in the resonator RC21 on the resonant circuit 120 side is described as being composed of a side electrode. However, it is also possible to use a side electrode to form the conductor in the resonator on the resonant circuit 110 side, or to use a side electrode as a basis for this. In addition, when each resonant circuit has multiple resonators, the conductor in a portion of the multiple resonators may also be composed of a side electrode.

[0103] (Variation Example 6)

[0104] In the filter device 100 of Embodiment 1, the structure of the resonant circuit 110 connected to the unbalanced terminal T1, which includes three resonators RC11, RC12, and RC13, has been described. However, the number of resonators included in each resonant circuit may also be one, as in the resonant circuit 120.

[0105] Figure 13 This is an equivalent circuit diagram of the filter device 100G in Modification Example 6. In the filter device 100G, the resonant circuit 110 in the filter device 100 is replaced by a resonant circuit 110A. In the filter device 100G, the descriptions of elements that are not repeated in the filter device 100 are omitted.

[0106] Reference Figure 13The resonant circuit 110A is composed of a resonator RC11, which is composed of an inductor L11 and a capacitor C11. That is, the filter device 100G is a structure that removes the resonators RC12 and RC13 in the filter device 100. As described above, in the filter device 100, the resonant circuit 110 on the unbalanced terminal T1 side functions as a bandpass filter by using three resonators. However, as long as the desired passband is different, the resonant circuit can also be composed of a single resonator, as in the filter device 100G of Modified Example 6.

[0107] In this structure, a short-circuit resonator is used in the resonant circuit connected to the unbalanced terminal on the input side, and an open-type resonator is used in the resonant circuit connected to the balanced terminal on the output side. This enables low-loss and good balance characteristics, and also allows for the miniaturization of the device.

[0108] (Variation Example 7)

[0109] In Modification 7, the structure of the resonant circuit connected to the balancing terminals T2 and T3 is described, which consists of multiple resonators.

[0110] Figure 14 This is the equivalent circuit diagram of filter device 100H in Modified Example 7. In filter device 100H, the resonant circuit 120 in filter device 100 is replaced by a resonant circuit 120A. In filter device 100H, the descriptions of elements that are not repeated in filter device 100 are omitted.

[0111] Reference Figure 14 In the filter device 100H, the resonant circuit 120A is configured to include two resonators RC21 and RC22. The resonator RC21 is connected to the balance terminals T2 and T3 in the same way as the resonant circuit 120 in Embodiment 1.

[0112] The resonator RC22 includes an inductor L22 and capacitors C22A and C22B. Capacitors C22A and C22B are connected in series, and the series-connected capacitors C22A and C22B are connected in parallel with the inductor L22. The connection node between capacitors C22A and C22B is connected to a reference potential. That is, the resonator RC22 corresponds to an open-type resonator where the inductor L22 is connected to a reference potential via capacitors C22A and C22B.

[0113] Resonator RC22 is positioned between resonator RC21 and resonator RC13 of resonant circuit 110. The signal supplied to the unbalanced terminal T1 is transmitted to resonator RC22 via resonators RC11, RC12, and RC13, and through electromagnetic coupling between resonator RC13 and resonator RC22. The signal transmitted to resonator RC22 is further transmitted from resonator RC22 to resonator RC21 via electromagnetic coupling, and is output from the balanced terminals T2 and T3.

[0114] In this way, even when the resonant circuit connected to the balanced terminal consists of multiple resonators, by using a short-circuit resonator for the resonant circuit connected to the unbalanced terminal on the input side and an open-type resonator for the resonant circuit connected to the balanced terminal on the output side, it is possible to achieve low-loss and good balance characteristics and to miniaturize the device.

[0115] [Implementation Method 2]

[0116] In Embodiment 2, an example of applying the structure of the filter device of Embodiment 1 in at least one filter device in a multiplex modulator composed of multiple filter devices will be described.

[0117] Figure 15 This is the equivalent circuit diagram of the duplexer 200 according to Embodiment 2. Figure 15 The example described here is a duplexer that includes two filter devices as a multiplexer, but a multiplexer may also include three or more filter devices.

[0118] Reference Figure 15 The duplexer 200 includes two filter devices 210 and 220 with different frequency bands. Filter device 210 is connected to the unbalanced terminal T11 via an inductor L50, which functions as a low-pass filter. Filter device 220 is connected to the unbalanced terminal T11 via a capacitor C70, which functions as a high-pass filter. The unbalanced terminal T11 is connected, for example, to an antenna (not shown). Filter device 210 is configured, for example, to allow signals in the 2 GHz band (2.4–2.5 GHz) to pass through. Filter device 220 is configured to allow signals in frequency bands higher than that of filter device 210, for example, the 5–7 GHz band (5.15–7.125 GHz) to pass through.

[0119] The filter device 210 includes a resonant circuit 211 connected to the unbalanced terminal T11 and a resonant circuit 212 connected to the balanced terminals T12A and T13A. The resonant circuit 211 is composed of three resonators RC51, RC52, and RC53. Each of the resonators RC51, RC52, and RC53 is a short-circuit resonator formed by connecting an inductor and a capacitor in parallel.

[0120] Resonator RC51 has an inductor L51 and a capacitor C51 connected in parallel. One connection node of resonator RC51 is connected to a reference potential, and the other connection node is connected to inductor L50. Resonator RC52 has an inductor L52 and a capacitor C52 connected in parallel. One connection node of resonator RC52 is connected to a reference potential, and the other connection node is connected to inductor L50 via capacitor C55. Resonator RC53 has an inductor L53 and a capacitor C53 connected in parallel. One connection node of resonator RC53 is connected to a reference potential, and the other connection node is connected to inductor L50 via capacitors C55 and C56.

[0121] The resonant circuit 212 includes a resonator RC61. The resonator RC61 has an inductor L61 and capacitors C61A and C61B. The inductor L61 is connected between the balancing terminals T12A and T13A. Additionally, capacitors C61A and C61B are connected in series between the balancing terminals T12A and T13A. That is, the series-connected capacitors C61A and C61B and the inductor L61 are connected in parallel between the balancing terminals T12A and T13A. The connection node between capacitors C61A and C61B is connected to a reference potential. Therefore, the resonator RC61 is an open-type resonator.

[0122] Similarly, the filter device 220 includes a resonant circuit 221 connected to the unbalanced terminal T11 and a resonant circuit 222 connected to the balanced terminals T12B and T13B. The resonant circuit 221 is composed of three resonators RC71, RC72, and RC73. Each of the resonators RC71, RC72, and RC73 is a short-circuit resonator formed by connecting an inductor and a capacitor in parallel.

[0123] Resonator RC71 has an inductor L71 and a capacitor C71 connected in parallel. One connection node of resonator RC71 is connected to a reference potential, and the other connection node is connected to capacitor C70. Resonator RC72 has an inductor L72 and a capacitor C72 connected in parallel. One connection node of resonator RC72 is connected to a reference potential, and the other connection node is connected to capacitor C70 via capacitor C75. Resonator RC73 has an inductor L73 and a capacitor C73 connected in parallel. One connection node of resonator RC73 is connected to a reference potential, and the other connection node is connected to capacitor C70 via capacitors C75 and C76.

[0124] The resonant circuit 222 includes a resonator RC81. ​​The resonator RC81 has an inductor L81 and capacitors C81A and C81B. The inductor L81 is connected between the balancing terminals T12B and T13B. Additionally, capacitors C81A and C81B are connected in series between the balancing terminals T12B and T13B. That is, the series-connected capacitors C81A and C81B and the inductor L81 are connected in parallel between the balancing terminals T12B and T13B. The connection node between capacitors C81A and C81B is connected to a reference potential. Therefore, the resonator RC81 is an open-type resonator.

[0125] Thus, each of the filter devices 210 and 220 has the same structure as the filter device 100 described in Embodiment 1, except for the connection of resonators RC52 and RC53 and the connection of resonators RC72 and RC73.

[0126] Figure 16 yes Figure 15 A three-dimensional view of the duplexer 200. Figure 17 This is an exploded perspective view of the duplexer 200. (Refer to...) Figure 16 as well as Figure 17 The duplexer 200 includes a dielectric substrate (laminated structure) 230 formed by stacking multiple dielectric layers (layer 11 to layer 24, LY24), having a generally rectangular parallelepiped shape. Multiple external electrodes, generally C-shaped, extending across the top, sides, and bottom surfaces, are provided on the outer surface of the dielectric substrate 230. These external electrodes are used for connection to external devices and also for connection between wiring patterns of the layers of the dielectric substrate 230. The external electrodes include an unbalanced terminal T11, balanced terminals T12A, T12B, T13A, T13B, and a ground electrode GND for connection to a reference potential. A directional mark DM1 indicating direction is affixed to the top surface of the dielectric substrate 230.

[0127] In duplexer 200, Figure 17 A filter device 210 is provided on the left side. Figure 17 A filter device 220 is provided on the right side of the dielectric substrate 230. The structure of the filter devices 210 and 220 in the dielectric substrate 230 will be described in detail below.

[0128] First, the filter device 210 on the low-frequency band side will be described. The unbalanced terminal T11 is connected to the wiring electrode L1A located on the thirteenth layer LY13. Wiring electrode L1A is connected in series with wiring electrode L1B located on the fourteenth layer LY14 and wiring electrode L1C located on the fifteenth layer LY15. Wiring electrodes L1A, L1B, and L1C constitute… Figure 15 The inductor L50 in the middle.

[0129] One end of wiring electrode L1C is connected to via V11A, which extends from layer 11 (LY11) to layer 21 (LY21) in the stacking direction (Z-axis direction). Via V11A is connected to wiring electrode LP1X in layer 11 (LY11). Additionally, via V11A is connected to planar electrode C6X in layer 19 (LY19) and to planar electrode C1X in layer 21 (LY21). Wiring electrode LP1X extends along the Y-axis in layer 11 (LY11) and is connected to via V11.

[0130] The via V11 extends from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction, and is connected to the planar electrode CG1 in the twenty-second layer LY22. The planar electrode CG1 is connected to the ground electrode GND disposed on the outer surface of the dielectric substrate 230.

[0131] It consists of vias V11 and V11A and wiring electrode LP1X. Figure 15 The inductor L51 is located in the middle. Additionally, the planar electrode C1X of the twenty-first layer LY21 and the planar electrode CG1 of the twenty-second layer LY22 are opposite to each other, forming a structure through the planar electrode C1X and the planar electrode CG1. Figure 15 The capacitor C51 is located within the circuit. Therefore, it is composed of vias V11 and V11A, wiring electrode LP1X, and planar electrodes C1X and CG1. Figure 15 The resonator RC51 in the middle.

[0132] It consists of a wiring electrode LP2X disposed on the eleventh layer LY11, a via V12A extending from the eleventh layer LY11 to the twentieth layer LY20 in the stacking direction, and a via V12 extending from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction. Figure 15 The inductor L52 is located in the middle. The planar electrode C2X, connected to the via V12A on the twentieth layer LY20, is opposite to the planar electrode CG1 located on the twenty-second layer LY22. The structure consists of the planar electrode C2X and the planar electrode CG1. Figure 15 The capacitor C52 is composed of vias V12 and V12A, wiring electrode LP2X, and planar electrodes C2X and CG1. Figure 15 The resonator RC52 is used in the circuit. Furthermore, a portion of the planar electrode C6X of the nineteenth layer LY19, connected to the via V11A, is opposite to the planar electrode C7X of the eighteenth layer LY18 connected to the via V12A, and the planar electrode C2X of the twentieth layer LY20. The circuit is composed of planar electrodes C2X, C6X, and C7X. Figure 15 The capacitor in the middle is C55.

[0133] It consists of a wiring electrode LP3X disposed on the eleventh layer LY11, a via V13A extending from the eleventh layer LY11 to the twentieth layer LY20 in the stacking direction, and a via V13 extending from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction. Figure 15 The inductor L53 is located in the middle. The planar electrode C3X, connected to the via V13A on the twentieth layer LY20, is opposite to the planar electrode CG1 located on the twenty-second layer LY22. The structure consists of the planar electrode C3X and the planar electrode CG1. Figure 15 The capacitor C53 is composed of vias V13 and V13A, wiring electrode LP3X, and planar electrodes C3X and CG1. Figure 15 The resonator RC53 is used in the circuit. Furthermore, the planar electrode C3X located on the twentieth layer LY20, the planar electrode C7X located on the eighteenth layer LY18, and the planar electrode C8X located on the seventeenth layer LY17 are partially opposite each other, forming a structure composed of planar electrodes C3X, C7X, and C8X. Figure 15 The capacitor in the middle is C56.

[0134] The resonator RC61 of resonant circuit 212 is composed of wiring electrode LP4X, planar electrodes C4X, C5X, CG1, CG2, and vias V14 and V14A. Wiring electrode LP4X is located on the eleventh layer LY11, the same as wiring electrodes LP1X, LP2X, and LP3X in resonant circuit 211. Wiring electrode LP4X is connected to vias V14 and V14A extending from the eleventh layer LY11 to the twenty-third layer LY23 in the stacking direction. It is composed of wiring electrode LP4X and vias V14 and V14A. Figure 15 The inductor L61 in the middle.

[0135] Vias V14 and V14A are connected to planar electrodes C5X and C4X respectively on the 23rd layer LY23. Planar electrode C4X is connected to the balance terminal T12A, and planar electrode C5X is connected to the balance terminal T13A. Planar electrodes C4X and C5X are opposite to planar electrode CG1 on the 22nd layer LY22 and planar electrode CG2 on the 24th layer LY24, respectively forming... Figure 15 Capacitors C61A and C61B are located in the middle. The planar electrode CG2 is connected to the ground electrode GND on the 24th layer LY24.

[0136] The inductors in resonators RC51, RC52, RC53, and RC61 are wound around a common winding shaft. Therefore, the high-frequency signal supplied to the unbalanced terminal T11 is transmitted through the electromagnetic coupling generated between the resonators and output from the balanced terminals T12A and T13A.

[0137] Next, the high-frequency band filter device 220 will be described. The planar electrode C0A, located on the eighteenth layer LY18, is connected to the unbalanced terminal T11. The planar electrode C0A is opposite to the planar electrode C0B, located on the seventeenth layer LY17. The device is composed of the planar electrode C0A and the planar electrode C0B. Figure 15 The capacitor in the middle is C70.

[0138] The planar electrode C0B is connected to one end of the wiring electrode LP1Y disposed on the eleventh layer LY11 via a via V21 extending from the eleventh layer LY11 to the eighteenth layer LY18 in the stacking direction. The other end of the wiring electrode LP1Y is connected to the planar electrode CG1 of the twenty-second layer LY22 via a via V21A extending from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction. That is, the wiring electrode LP1Y and the vias V21 and V21A constitute a complete structure. Figure 15 The inductor L71. The planar electrode C1Y, connected to the via V21 on the sixteenth layer LY16, and the planar electrode CG1, located on the twenty-second layer LY22, are opposite each other. The inductor L71 is composed of the planar electrode C1Y and the planar electrode CG1. Figure 15 The capacitor C71 is composed of vias V21 and V21A, wiring electrode LP1Y, plate electrode C1Y, and CG1. Figure 15 The resonator RC71 in the middle.

[0139] It consists of a wiring electrode LP2Y disposed on the eleventh layer LY11, a via V22A extending from the eleventh layer LY11 to the seventeenth layer LY17 in the stacking direction, and a via V22 extending from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction. Figure 15 The inductor L72 is located in the middle. The planar electrode C2Y, connected to the via V22A on the seventeenth layer LY17, and the planar electrode CG1, located on the twenty-second layer LY22, are opposite each other. The structure consists of the planar electrode C2Y and the planar electrode CG1. Figure 15 The capacitor C72 is composed of vias V22 and V22A, wiring electrode LP2Y, plate electrode C2Y, and CG1. Figure 15 The resonator RC72 is used in this circuit. Furthermore... Figure 15 The capacitor C75 between the resonator RC71 and the resonator RC72 is formed by the parasitic capacitance between the inductor L71, which is composed of wiring electrodes LP1Y and through holes V21 and V21A, and the inductor L72, which is composed of wiring electrodes LP2Y and through holes V22 and V22A.

[0140] It consists of a wiring electrode LP3Y disposed on the eleventh layer LY11, a via V23 extending from the eleventh layer LY11 to the seventeenth layer LY17 in the stacking direction, and a via V23A extending from the eleventh layer LY11 to the twenty-second layer LY22 in the stacking direction. Figure 15 The inductor L73 is located in the middle. The planar electrode C3Y, connected to the via V23 on the seventeenth layer LY17, and the planar electrode CG1, located on the twenty-second layer LY22, are opposite each other. The structure consists of the planar electrode C3Y and the planar electrode CG1. Figure 15 The capacitor C73 is composed of vias V23 and V23A, wiring electrode LP3Y, plate electrode C3Y, and CG1. Figure 15 The resonator RC73 is used in this circuit. Furthermore... Figure 15 The capacitor C76 between the resonators RC72 and RC73 is formed by the parasitic capacitance between the inductor L72, which is composed of wiring electrodes LP2Y and vias V22 and V22A, and the inductor L73, which is composed of wiring electrodes LP3Y and vias V23 and V23A.

[0141] The resonator RC81 of resonant circuit 222 is composed of wiring electrode LP4Y, planar electrodes C4Y, C5Y, CG1, and vias V24 and V24A. Wiring electrode LP4Y is located on the eleventh layer LY11, the same as wiring electrodes LP1Y, LP2Y, and LP3Y in resonant circuit 221. Wiring electrode LP4Y is connected to vias V24 and V24A extending from the eleventh layer LY11 to the twentieth layer LY20 in the stacking direction. It is composed of wiring electrode LP4Y and vias V24 and V24A. Figure 15 The inductor L81 in the middle.

[0142] Vias V24 and V24A are connected to planar electrodes C5Y and C4Y respectively on the twentieth layer LY20. Planar electrode C4Y is connected to the balance terminal T12B, and planar electrode C5Y is connected to the balance terminal T13B. Planar electrodes C4Y and C5Y are opposite to planar electrode CG1 located on the twenty-second layer LY22, forming... Figure 15 Capacitors C81A and C81B are included.

[0143] Furthermore, the planar electrode C6Y located on the twelfth layer LY12 is opposite to the wiring electrode LP4Y of resonator RC81 and the wiring electrode LP3Y of resonator RC73. The wiring electrodes LP4Y and LP3Y are capacitively coupled through the planar electrode C6Y. As explained in Modification 2 above, the difference between the line length of resonator RC73 and the line length of resonator RC81 is adjusted by using the capacitive coupling of the planar electrode C6Y.

[0144] The inductors in resonators RC71, RC72, RC73, and RC81 are wound around a common winding shaft. Therefore, the high-frequency signal supplied to the unbalanced terminal T11 is transmitted through the electromagnetic coupling generated between the resonators and output from the balanced terminals T12B and T13B.

[0145] As described above, in a multiplexer that includes two or more filter devices, the filter devices described in Embodiment 1 and its variations are used as at least one filter device, thereby suppressing the degradation of filter characteristics and achieving miniaturization.

[0146] Furthermore, in the resonant circuit 211 of the filter device 210, the vias V11, V12, and V13 connected to the reference potential are arranged on the same side, and the direction of the current flowing through each resonator is the same. On the other hand, in the resonant circuit 221 of the filter device 220, the vias connected to the reference potential are arranged alternately with the vias V21A, V22, and V23A, and the direction of the current flowing through the resonator RC72 is the same as the direction of the current flowing through the resonators RC71 and RC73. The arrangement of the vias connected to the reference potential is appropriately set according to the bandwidth being targeted.

[0147] It should be considered that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the invention is defined by the claims rather than by the description of the embodiments described above, and is intended to include the equivalents of the claims and all modifications within the scope.

[0148] Explanation of reference numerals in the attached figures

[0149] 1…Communication devices; 10…Front-end circuits; 20…RFICs; 100, 100A~100H, 210, 220…Filter devices; 110, 110A, 120, 120A, 211, 212, 221, 222…Resonant circuits; 130, 230…Dielectric substrates; 200…Duplexers; ANT…Antennas; C0~C6, C0A, C0B, C1X~C8X, C1Y~C6Y, CG, CG1, C G2…plate electrode; C11~C13, C15, C21A, C21B, C22A, C22B, C51~C53, C55, C56, C61A, C61B, C70~C73, C75, C76, C81A, C81B…capacitors; DM, DM1…directional markers; FLT1, FLT2…filters; GND…ground electrode; L1A~L1C, LP1~LP4, LP1X~LP4X LP1Y~LP4Y, LP4A~LP4D… wiring electrodes; L11~L13, L21, L22, L50~L53, L61, L71~L73, L81… inductors; LNA… low-noise amplifier; LY1~LY5, LY11~LY24… dielectric layers; PA… power amplifier; RC11~RC13, RC21, RC22, RC51~RC53, RC61, RC71~RC73 RC81…Resonator; RX…Receiver side line; SW…Switch; T1, T11…Unbalanced terminal; T2, T3, T12A, T12B, T13A, T13B…Balanced terminal; TA…Selection terminal; TC…Common terminal; TDF…Power supply terminal; TX…Transmitter side line; V1~V6, V1A~V3A, V11~V14, V11A~V14A, V21~V24, V21A~V24A…Through holes.

Claims

1. A filter device comprising: A laminate consisting of multiple dielectric layers; Unbalanced terminals; First balancing terminal and second balancing terminal; A first resonant circuit connected to the aforementioned unbalanced terminals; A second resonant circuit connected to the first and second balanced terminals and electromagnetically coupled to the first resonant circuit; and Coupled electrode, The aforementioned first resonant circuit includes a first resonator, which is formed by connecting a first inductor and a first capacitor in parallel between the unbalanced terminal and the reference potential. The second resonant circuit includes a second resonator, which comprises: a second inductor connected between the first balanced terminal and the second balanced terminal, and a second capacitor and a third capacitor connected in series between the first balanced terminal and the second balanced terminal. The aforementioned plurality of dielectric layers include a first layer, The first inductor is composed of a first wiring electrode disposed on the first layer, a first conductor connected to the first wiring electrode and extending in the stacking direction of the laminate, and a second conductor. The second inductor is composed of a second wiring electrode disposed on the first layer, and a third conductor and a fourth conductor connected to the second wiring electrode and extending in the stacking direction of the laminate. The line length of the second wiring electrode is longer than the line length of the first wiring electrode. The aforementioned coupling electrodes constitute capacitive coupling between the first wiring electrode and the second wiring electrode.

2. The filter device according to claim 1, wherein, The line length of the second inductor is longer than that of the first inductor.

3. The filter device according to claim 1, wherein, Viewed from the stacking direction of the aforementioned stack, the second wiring electrode has a path extending from the connection point with the third and fourth conductors in a direction away from the first resonant circuit.

4. The filter device according to claim 1, wherein, Viewed from the stacking direction of the aforementioned stack, the second wiring electrode has a path extending from the connection point with the third and fourth conductors toward the first resonant circuit.

5. The filter device according to any one of claims 1 to 4, wherein, The distance between the third conductor and the fourth conductor is wider than the distance between the first conductor and the second conductor.

6. The filter device according to any one of claims 1 to 4, wherein, The lengths of the third conductor and the fourth conductor are equal. The filter device described above also includes a power supply terminal connected to the central portion of the second wiring electrode.

7. The filter device according to any one of claims 1 to 4, wherein, The first conductor and the second conductor are composed of side electrodes disposed on the side of the laminate.

8. The filter device according to any one of claims 1 to 4, wherein, The aforementioned third conductor and the aforementioned fourth conductor are composed of side electrodes disposed on the side of the aforementioned laminate.

9. The filter device according to any one of claims 1 to 4, wherein, The first to fourth conductors mentioned above are formed by through holes.

10. The filter device according to claim 1, wherein, Each of the aforementioned first resonant circuit and second resonant circuit includes at least one LC parallel resonator. The aforementioned at least one LC parallel resonator includes a conductor extending in the stacking direction of the aforementioned laminate. The conductor in at least one of the above-mentioned at least LC parallel resonators is composed of a side electrode disposed on the side of the above-mentioned stack.

11. The filter device according to any one of claims 1 to 4, wherein, The connection node between the second capacitor and the third capacitor is connected to a reference potential.

12. The filter device according to claim 1, wherein, When viewed from the stacking direction of the above-mentioned stack, the coupling electrode is disposed at a position that overlaps with at least a portion of the first wiring electrode and at least a portion of the second wiring electrode.

13. A filter device comprising: A laminate consisting of multiple dielectric layers; Unbalanced terminals; First balancing terminal and second balancing terminal; A first resonant circuit connected to the aforementioned unbalanced terminals; A second resonant circuit connected to the first and second balanced terminals and electromagnetically coupled to the first resonant circuit; and Coupled electrode, The aforementioned first resonant circuit includes a first resonator, which is formed by connecting a first inductor and a first capacitor in parallel between the unbalanced terminal and the reference potential. The second resonant circuit includes a second resonator, which comprises: a second inductor connected between the first balanced terminal and the second balanced terminal, and a second capacitor and a third capacitor connected in series between the first balanced terminal and the second balanced terminal. The aforementioned plurality of dielectric layers include a first layer, The first inductor is composed of a first wiring electrode disposed on the first layer, a first conductor connected to the first wiring electrode and extending in the stacking direction of the laminate, and a second conductor. The second inductor is composed of a second wiring electrode disposed on the first layer, and a third conductor and a fourth conductor connected to the second wiring electrode and extending in the stacking direction of the laminate. The aforementioned coupling electrodes constitute capacitive coupling between the first wiring electrode and the second wiring electrode.

14. The filter device according to claim 13, wherein, The first conductor and the second conductor are composed of side electrodes disposed on the side of the laminate.

15. The filter device according to claim 13 or 14, wherein, The aforementioned third conductor and the aforementioned fourth conductor are composed of side electrodes disposed on the side of the aforementioned laminate.

16. The filter device according to claim 13, wherein, The first to fourth conductors mentioned above are formed by through holes.

17. The filter device according to claim 13 or 14, wherein, The connection node between the second capacitor and the third capacitor is connected to a reference potential.

18. The filter device according to claim 13, wherein, When viewed from the stacking direction of the above-mentioned stack, the coupling electrode is disposed at a position that overlaps with at least a portion of the first wiring electrode and at least a portion of the second wiring electrode.

19. A multiplexer, comprising: First terminal; A first filter device connected to the first terminal via an inductor; and A second filter device connected to the first terminal via a capacitor. The first filter device and at least one of the second filter devices described above are formed by the filter device described in any one of claims 1 to 18.

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