WO2023026990A1

WO2023026990A1 - Filter device and composite filter device

Info

Publication number: WO2023026990A1
Application number: PCT/JP2022/031418
Authority: WO
Inventors: 直樹大島; 直人吉田
Original assignee: 株式会社村田製作所
Priority date: 2021-08-24
Filing date: 2022-08-19
Publication date: 2023-03-02

Abstract

Provided are a filter device and a composite filter device that have achieved improved isolation characteristics without degradation in pass characteristics.　This filter device is provided with: an input terminal 3 and an output terminal 4; an input/output terminal-side signal wire 7A connected to the input terminal 3 or the output terminal 4; at least one series arm resonator; at least one parallel arm resonator; a plurality of ground terminals 6; and a first ground wire 8 and a second ground wire 9 that are connected to mutually different ground terminals 6. The input/output terminal-side signal wire 7A includes a portion extending alongside and adjacent to the first ground wire 8, and a portion extending alongside and adjacent to the second ground wire 9.

Description

Filter device and composite filter device

The present invention relates to a filter device and a composite filter device.

Conventionally, filter devices have been widely used in mobile phones and the like. Ladder filters are used as a transmission filter and a reception filter in the duplexer described in Patent Document 1 below. In this duplexer, the shield electrode extends to near the antenna port. The shield electrode is connected to the ground electrode.

JP 2012-095268 A

There is a trade-off between the pass characteristics of the transmission filter and the reception filter and the isolation characteristics. Therefore, it is difficult to achieve both of these. For example, in the duplexer disclosed in Patent Literature 1, the shield electrode extends to the vicinity of the antenna port, thereby improving isolation characteristics. On the other hand, the duplexer deteriorates in pass characteristics.

An object of the present invention is to provide a filter device and a composite filter device capable of improving isolation characteristics without deteriorating pass characteristics.

A filter device according to the present invention includes an input terminal and an output terminal, input/output terminal side signal wiring connected to the input terminal or the output terminal, at least one series arm resonator, and at least one parallel arm resonator. a plurality of ground terminals; and a first ground wiring and a second ground wiring connected to the different ground terminals, wherein the input/output terminal side signal wiring is connected to the first ground wiring. and a portion extending alongside and adjacent to the second ground wiring.

In a broad aspect of the composite filter device according to the present invention, a plurality of filter devices sharing a common connection terminal are provided, and at least one filter device is a filter device configured according to the present invention. be.

In another broad aspect of the composite filter device according to the present invention, a common connection terminal is shared for at least one series arm resonator, at least one parallel arm resonator, and at least one ground terminal, respectively. a first filter device and a second filter device; a common connection terminal side signal wiring connected to the common connection terminal; and a third ground wiring and a fourth ground wiring connected to the different ground terminals. wherein the common connection terminal side signal wiring extends along and adjacent to the third ground wiring and extends along and adjacent to the fourth ground wiring. have a part that

According to the present invention, it is possible to provide a filter device and a composite filter device capable of improving isolation characteristics without deteriorating pass characteristics.

FIG. 1 is a circuit diagram of a filter device according to a first embodiment of the invention. FIG. 2 is a schematic plan view of the filter device according to the first embodiment of the invention. FIG. 3 is a diagram showing attenuation frequency characteristics of the filter devices of the first embodiment and the first comparative example of the present invention. FIG. 4 is a diagram showing, in a wide range, the attenuation frequency characteristics of the filter devices of the first embodiment and the first comparative example of the present invention. FIG. 5 is a circuit diagram of a composite filter device according to a second embodiment of the invention. FIG. 6 is a schematic plan view of a composite filter device according to a second embodiment of the invention. FIG. 7 is a diagram showing attenuation frequency characteristics of the first filter device in the second embodiment and the second comparative example of the present invention. FIG. 8 is a diagram showing, in a wide range, attenuation frequency characteristics of the first filter device in the second embodiment and the second comparative example of the present invention. FIG. 9 is a diagram showing isolation characteristics of the composite filter devices of the second embodiment and the second comparative example of the present invention. FIG. 10 is a circuit diagram of a composite filter device according to a third embodiment of the invention. FIG. 11 is a schematic plan view of a composite filter device according to a third embodiment of the invention. FIG. 12 is a circuit diagram of a composite filter device according to a fourth embodiment of the invention. FIG. 13 is a schematic plan view of a composite filter device according to a fourth embodiment of the invention. FIG. 14 is a circuit diagram of a composite filter device according to a modification of the fourth embodiment of the invention. FIG. 15 is a schematic diagram of a composite filter device according to a fifth embodiment of the invention.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

It should be noted that each embodiment described in this specification is an example, and partial replacement or combination of configurations is possible between different embodiments.

FIG. 1 is a circuit diagram of a filter device according to the first embodiment of the present invention. In FIG. 1, each resonator group surrounded by a dashed line is shown as one resonator. A group of resonators surrounded by a dashed line is a series-divided resonator or a parallel-divided resonator. The same applies to other circuit diagrams.

The filter device 1 is a ladder filter. Filter device 1 is used, for example, in a composite filter device such as a duplexer or multiplexer. In this embodiment, the filter device 1 is a transmission filter. The pass band of the filter device 1 is the transmission band of Band 30 . Specifically, the pass band of the filter device 1 is 2305-2315 MHz. Note that the passband of the filter device 1 is not limited to the above. Furthermore, the filter device 1 may be a receive filter.

The filter device 1 has an input terminal 3, an output terminal 4, a plurality of series arm resonators and a plurality of parallel arm resonators. The input terminal 3 and the output terminal 4 are configured as electrode pads. These electrode pads are provided with connection members for connecting the filter device 1 and circuits and devices outside the filter device 1 . A solder bump, a conductive adhesive, or the like is used as the connection member. However, the input terminal 3 and the output terminal 4 may be configured as wiring. In this embodiment, the plurality of series arm resonators and the plurality of parallel arm resonators include series-divided resonators or parallel-divided resonators. It should be noted that none of the series arm resonators and parallel arm resonators may be divided in series or parallel.

The plurality of series arm resonators of the filter device 1 are a series arm resonator S1, a series arm resonator S2, a series arm resonator S3, and a series arm resonator S4. The plurality of parallel arm resonators of the filter device 1 are a parallel arm resonator P1, a parallel arm resonator P2, and a parallel arm resonator P3. In this embodiment, both the series arm resonators and the parallel arm resonators are elastic wave resonators. Each elastic wave resonator has an IDT (Interdigital Transducer) electrode. The IDT electrode has a plurality of electrode fingers. In this embodiment, the elastic wave resonators are arranged such that the directions in which the plurality of electrode fingers of each elastic wave resonator extend are parallel.

Between the input terminal 3 and the output terminal 4, a series arm resonator S1, a series arm resonator S2, a series arm resonator S3, and a series arm resonator S4 are connected in series. A parallel arm resonator P1 is connected between the connection point between the series arm resonators S1 and S2 and the ground potential. A parallel arm resonator P2 is connected between the connection point between the series arm resonators S2 and S3 and the ground potential. A parallel arm resonator P3 is connected between the connection point between the series arm resonators S3 and S4 and the ground potential. A ground potential is a potential that serves as a reference when operating a device such as a filter device. The ground potential is usually set to 0V in many cases. However, the ground potential is not limited to 0V. Note that the circuit configuration of the filter device 1 is not limited to the above. The filter device 1 may have at least one series arm resonator and at least one parallel arm resonator.

FIG. 2 is a schematic plan view of the filter device according to the first embodiment. In FIG. 2, the acoustic wave resonator is shown schematically by adding two diagonal lines to a rectangle. Further, in FIG. 2, among input/output terminal-side signal wirings, first ground wirings, and second ground wirings, which will be described later, wirings forming a capacitor portion, and terminals connected to the wirings are hatched. is emphasized by . Hatching may be attached to a part of the wiring or terminal in some cases. The same applies to other schematic plan views.

The filter device 1 has a piezoelectric substrate 5 . Each elastic wave resonator is formed on the piezoelectric substrate 5 . Furthermore, the piezoelectric substrate 5 is provided with an input terminal 3, an output terminal 4, a plurality of ground terminals 6, a plurality of signal wirings, and a plurality of ground wirings. The plurality of signal wirings include an input/output terminal side signal wiring 7A and an input/output terminal side signal wiring 7B. The input/output terminal side signal wiring 7A is connected to the input terminal 3. As shown in FIG. The input/output terminal side signal wiring 7B is connected to the output terminal 4 . Furthermore, the plurality of signal wirings includes signal wirings connecting acoustic wave resonators.

On the other hand, each of the plurality of ground wirings is connected to the ground terminal 6 . Each ground terminal 6 is connected to a ground potential outside the filter device 1 . Therefore, each parallel arm resonator is connected to ground potential through each ground terminal 6 . An inductor may be provided between the parallel arm resonator and the ground terminal 6, although it is omitted in FIG. In this case, the inductor may be, for example, a wiring pattern provided on the piezoelectric substrate 2 . Similarly, ground terminal 6 may be connected to ground potential via an inductor. In this case, the inductor may be, for example, an inductor element or a conductor pattern. Then, as shown in FIG. 2 , the plurality of ground wirings includes first ground wiring 8 and second ground wiring 9 . More specifically, the first ground wiring 8 is indirectly connected to the parallel arm resonator P1 via the ground terminal 6. As shown in FIG. The parallel arm resonator P1 is the first parallel arm resonator in the present invention. A second ground wiring 9 is indirectly connected to the parallel arm resonator P3 via the ground terminal 6 . The parallel arm resonator P3 is the second parallel arm resonator in the present invention. The first ground wiring 8 and the second ground wiring 9 are connected to ground terminals 6 different from each other.

As shown in FIG. 2, portions of the first ground wiring 8 and the second ground wiring 9 are arranged so as to sandwich a portion of the input/output terminal side signal wiring 7A. A portion of the input/output terminal side signal wiring 7A and a portion of the first ground wiring 8 face each other. More specifically, in a plan view, a part of one side that constitutes the input/output terminal side signal wiring 7A and a part of one side that constitutes the first ground wiring 8 are spaced apart from each other at a constant interval. have a part Thus, the capacitor section C2 shown in FIG. 1 is configured. A portion of the input/output terminal side signal wiring 7A and a portion of the second ground wiring 9 face each other. More specifically, in a plan view, a part of one side of the input/output terminal side signal wiring 7A and a part of one side of the second ground wiring 9 are separated from each other without any other wiring therebetween. have portions spaced apart at regular intervals. Thus, the capacitor C1 shown in FIG. 1 is configured. In this specification, the term “planar view” refers to a direction in which a plan view such as FIG. 2 is viewed in the depth direction of the page.

The feature of this embodiment is that the input/output terminal side signal wiring 7A extends side by side with the first ground wiring 8 and extends side by side with the second ground wiring 9, and also extends side by side with the second ground wiring 9. to have More specifically, the portion of the input/output terminal side signal wiring 7A having the length direction and the portion of the first ground wiring 8 having the length direction are opposed to each other without interposing other electrodes. there is The positional relationship between the input/output terminal side signal wiring 7A and the second ground wiring 9 is the same. With the filter device 1 configured as described above, it is possible to improve the isolation characteristics without degrading the pass characteristics. Details of this will be shown below by comparing the present embodiment and the first comparative example.

The first comparative example differs from the first embodiment in that the first ground wiring 8 is not provided. The attenuation frequency characteristics of the filter devices of the first embodiment and the first comparative example were compared. The passband of the filter devices of the first embodiment and the first comparative example was the transmission band of Band30.

FIG. 3 is a diagram showing attenuation frequency characteristics of the filter devices of the first embodiment and the first comparative example. FIG. 4 is a diagram showing attenuation frequency characteristics of the filter devices of the first embodiment and the first comparative example over a wide range. Band W1 in FIG. 3 is the passband of the filter device. Band W2 is the reception band of Band30.

As shown in FIG. 3, it can be seen that the attenuation in the band W2 is greater in the filter device 1 of the first embodiment than in the first comparative example. Therefore, in the filter device 1, attenuation can be increased in the passband of the reception filter of Band 30. FIG. Therefore, when the filter device 1 of the first embodiment is used for the duplexer of Band 30, isolation characteristics can be improved. Furthermore, it can be seen that the pass characteristics of the filter device 1 in the first embodiment are almost the same as the pass characteristics in the first comparative example.

As shown in FIG. 4, in the filter device 1 of the first embodiment, the attenuation can be increased not only in the band W2 but also over a wide band. Therefore, isolation characteristics can be improved regardless of the communication band of the duplexer. From the above, it can be seen that in the first embodiment, the isolation characteristic can be improved without deteriorating the pass characteristic. This is for the following reasons.

As shown in FIG. 2, in the first embodiment, the input/output terminal side signal wiring 7A extends along and adjacent to the first ground wiring 8, and extends along the second ground wiring 9. and have portions that extend contiguously with. In this specification, "adjacent" means that there are no elements such as resonators or wiring between them. Thereby, as shown in FIG. 1, the capacitive section C1 and the capacitive section C2 are configured. More specifically, in the filter device 1, a first sub-circuit including a capacitive section C1 is provided between the input terminal 3 and the parallel arm resonator P3. The end of the first sub-circuit on the input terminal 3 side is connected to the series arm resonator S1. The provision of the first sub-circuit changes the capacitance of the series arm resonator S1. Thereby, the attenuation of the filter device 1 can be increased in a wide band. The distance between the input/output terminal side signal wiring 7A and the first ground wiring 8 in the portion where the capacitance section C1 is formed is preferably 50 μm or less. More preferably, the distance is 3 μm or more and 30 μm or less. In the present invention, the distance between the signal wiring and the ground wiring in the portion where the capacitive section other than the capacitive section C1 is formed is also preferably 50 μm or less. More preferably, the distance is 3 μm or more and 30 μm or less.

Furthermore, a second sub-circuit including a capacitance section C2 is provided between the input terminal 3 and the parallel arm resonator P1. The capacitance section C2 acts as a parallel capacitance for the series arm resonator S1 and the parallel arm resonator P1. Thereby, capacitance is added to the series arm resonator S1 and the parallel arm resonator P1. Along with this, the frequencies of the anti-resonance points of the series arm resonator S1 and the parallel arm resonator P1 are lowered. This changes the frequency of the attenuation pole. Therefore, the attenuation on the high frequency side of the passband of the filter device 1 can be locally increased. Moreover, the first sub-circuit and the second sub-circuit hardly affect the transmission characteristics. Therefore, in the first embodiment, the isolation characteristic can be improved without deteriorating the pass characteristic.

The input/output terminal side signal wiring 7A preferably has a portion sandwiched between the first ground wiring 8 and the second ground wiring 9 . Thereby, the first ground wiring 8 and the second ground wiring 9 function as electromagnetic shields. Therefore, the influence of an electric field from the outside can be suppressed, and the filter characteristics are less likely to deteriorate.

In this embodiment, one end of the first sub-circuit is connected to a parallel arm resonator P3 as a second parallel arm resonator. One end of the second subcircuit is connected to a parallel arm resonator P1 as a first parallel arm resonator. In this case, it is preferable that at least one series arm resonator is connected between the first parallel arm resonator and the second parallel arm resonator. As a result, attenuation outside the passband can be effectively increased.

It should be noted that one end of each of the first sub-circuit and the second sub-circuit does not necessarily have to be connected to the parallel arm resonator. At least one of the first ground wiring 8 and the second ground wiring 9 may be connected to the parallel arm resonator. Alternatively, at least one of the first ground wiring 8 and the second ground wiring 9 may not be connected to the parallel arm resonator. In this case, at least one of the first ground wiring 8 and the second ground wiring 9 should be connected to the ground terminal 6 that is not connected to the parallel arm resonator. Even in these cases, the attenuation outside the passband can be increased.

An example of a composite filter device according to the present invention is shown below.

FIG. 5 is a circuit diagram of a composite filter device according to the second embodiment.

The composite filter device 10 is a duplexer. The composite filter device 10 has a first filter device 11A and a second filter device 11B. The first filter device 11A is a transmission filter and the second filter device 11B is a reception filter. In this embodiment, the communication band of the composite filter device 10 is Band30. Therefore, the pass band of the first filter device 11A is 2305-2315 MHz. The pass band of the second filter device 11B is 2350-2360 MHz. Note that the communication band of the composite filter device 10 is not limited to the above.

The first filter device 11A and the second filter device 11B share a common connection terminal 12. In FIG. 5, the common connection terminal 12 is not included in the first filter device 11A and the second filter device 11B for the sake of clarity. The same applies to the circuit diagrams of the composite filter device other than FIG. In this embodiment, the common connection terminal 12 is an antenna terminal. An antenna terminal is connected to the antenna. Therefore, the first filter device 11A and the second filter device 11B are commonly connected to the antenna through the common connection terminal 12 . The common connection terminal 12 functions as an output terminal of the first filter device 11A. On the other hand, the common connection terminal 12 also functions as an input terminal of the second filter device 11B. The common connection terminal 12 is configured as an electrode pad. However, the common connection terminal 12 may be configured as wiring.

The first filter device 11A has the same configuration as the filter device 1 of the first embodiment. On the other hand, the second filter device 11B is not a filter device according to the invention. The second filter device 11B may also be the filter device of the present invention. The composite filter device 10 need only have at least one filter device according to the invention. Composite filter device 10 may be a multiplexer.

The second filter device 11B is a ladder filter. The second filter device 11B has a common connection terminal 12 as an input terminal, an output terminal 14, a plurality of series arm resonators, and a plurality of parallel arm resonators. The plurality of series arm resonators of the second filter device 11B are a series arm resonator S11, a series arm resonator S12, a series arm resonator S13, a series arm resonator S14, a series arm resonator S15, and a series arm resonator S16. and a series arm resonator S17. The plurality of parallel arm resonators of the second filter device 11B are a parallel arm resonator P11, a parallel arm resonator P12, a parallel arm resonator P13, a parallel arm resonator P14 and a parallel arm resonator P15. In this embodiment, both the series arm resonators and the parallel arm resonators are elastic wave resonators.

A series arm resonator S11, a series arm resonator S13, a series arm resonator S14, a series arm resonator S15, and a series arm resonator S16 are connected in series between a common connection terminal 12 as an input terminal and an output terminal 14. It is The series arm resonator S11 and the series arm resonator S12 are connected in parallel between the common connection terminal 12 and the series arm resonator S13. A series arm resonator S16 and a series arm resonator S17 are connected in parallel between the series arm resonator S15 and the output terminal 14 .

A parallel arm resonator P11 is connected between the connection point between the series arm resonators S11 and S13 and the ground potential. A parallel arm resonator P12 and a parallel arm resonator P13 are connected in series between a connection point between the series arm resonator S13 and the series arm resonator S14 and the ground potential. A parallel arm resonator P14 is connected between the connection point between the series arm resonator S14 and the series arm resonator S15 and the ground potential. A parallel arm resonator P15 is connected between the connection point between the series arm resonator S15 and the series arm resonator S16 and the ground potential. However, the circuit configuration of the second filter device 11B is not limited to the above.

Furthermore, a capacitive element C is provided between the connection point between the series arm resonator S11 and the series arm resonator S13 in the second filter device 11B and the parallel arm resonator P3 of the first filter device 11A. It is In this embodiment, one end of the capacitive section C1 in the first filter device 11A is connected to a connection point between the parallel arm resonator P3 and the capacitive element C. As shown in FIG. However, the capacitive part C1 is connected to the ground potential as in the first embodiment. Note that the capacitive element C may not be provided. The first filter device 11A and the second filter device 11B may not be connected at a portion other than the common connection terminal 12. FIG.

FIG. 6 is a schematic plan view of the composite filter device according to the second embodiment. In FIG. 6, the elastic wave resonator and the capacitive element C are shown by a schematic diagram of a rectangle with two diagonal lines added. Furthermore, in FIG. 6, the first filter device 11A and the second filter device 11B are shown without including the common connection terminal 12 for the sake of clarity. These are the same for other schematic plan views.

The piezoelectric substrate 5 is shared by the first filter device 11A and the second filter device 11B. Each elastic wave resonator is formed on the piezoelectric substrate 5 . Each wiring of the first filter device 11A is provided in the same manner as in the first embodiment except for the common connection terminal 12 and the common connection terminal side signal wiring 17C. The common connection terminal side signal wiring 17C is a signal wiring connected to the common connection terminal 12. As shown in FIG. On the other hand, each wiring of the second filter device 11B is also provided appropriately. In this embodiment, the parallel arm resonator P11 and the parallel arm resonator P13 are commonly connected to the same ground terminal 6 . The parallel arm resonator P14 and the parallel arm resonator P15 are commonly connected to the same ground terminal 6 . Further, the second filter device 11B has an input/output terminal side signal wiring 17B. The input/output terminal side signal wiring 17B is connected to the output terminal 14 . By the way, the capacitive element C is of the IDT type. Therefore, the capacitive element C has a plurality of electrode fingers. The capacitive element C is arranged such that the direction in which the electrode fingers of the capacitive element C extend is orthogonal to the direction in which the electrode fingers of each elastic wave resonator extend. Note that the direction in which the plurality of electrode fingers of the capacitive element C extend is not limited to the above.

Also in this embodiment, similarly to the first embodiment, it is possible to improve the isolation characteristic without deteriorating the pass characteristic. This is shown below by comparing the present embodiment and the second comparative example.

The second comparative example differs from the second embodiment in that the first ground wiring 8 is not provided. The attenuation frequency characteristics of the first filter device in the second embodiment and the second comparative example were compared. Furthermore, the isolation characteristics of the composite filter devices of the second embodiment and the second comparative example were compared.

FIG. 7 is a diagram showing attenuation frequency characteristics of the first filter device in the second embodiment and the second comparative example. FIG. 8 is a diagram showing the attenuation frequency characteristics of the first filter device in the second embodiment and the second comparative example over a wide range. FIG. 9 is a diagram showing isolation characteristics of the composite filter devices of the second embodiment and the second comparative example.

As shown in FIG. 7, in the first filter device 11A of the second embodiment, the maximum attenuation in the band W2 is larger than that of the second comparative example. Furthermore, it can be seen that the pass characteristic of the first filter device 11A in the second embodiment is almost the same as the pass characteristic in the second comparative example. As shown in FIG. 8, in the first filter device 11A of the second embodiment, the attenuation can be increased not only in the band W2 but also over a wide band. As shown in FIG. 9, in the composite filter device 10 of the second embodiment, the isolation characteristics can be significantly improved as compared with the second comparative example. As described above, in the second embodiment, the isolation characteristic can be improved without deteriorating the pass characteristic.

FIG. 10 is a circuit diagram of a composite filter device according to the third embodiment. FIG. 11 is a schematic plan view of a composite filter device according to a third embodiment;

As shown in FIG. 10, this embodiment differs from the second embodiment in that the second filter device 21B is the filter device according to the present invention. Except for the above points, the composite filter device of this embodiment has the same configuration as the composite filter device 10 of the second embodiment.

As shown in FIG. 11, the second filter device 21B has a first ground wiring 28 and a second ground wiring 29. The first ground wiring 28 is indirectly connected to the parallel arm resonator P11 and the parallel arm resonator P13 via the ground terminal 6 . The second ground wiring 29 is connected to the parallel arm resonator P14 and the parallel arm resonator P15. Parts of the first ground wiring 28 and the second ground wiring 29 are arranged so as to sandwich a part of the input/output terminal side signal wiring 17B.

A portion of the input/output terminal side signal wiring 17B and a portion of the first ground wiring 28 face each other. Thus, the capacitor section C3 shown in FIG. 10 is configured. A portion of the input/output terminal side signal wiring 17B and a portion of the second ground wiring 29 face each other. Thereby, the capacitor section C4 shown in FIG. 10 is configured. More specifically, in the second filter device 21B, a third sub-circuit including the capacitance section C3 is provided between the output terminal 14 and the parallel arm resonators P11 and P13. . Furthermore, a fourth sub-circuit including a capacitance section C4 is provided between the output terminal 14 and the parallel arm resonators P14 and P15. As a result, the amount of attenuation outside the passband is increased in the second filter device 21B. Moreover, the third sub-circuit and the fourth sub-circuit hardly affect the transmission characteristics.

As described above, in addition to the first filter device 11A, also in the second filter device 21B, the attenuation amount outside the passband can be increased without deteriorating the pass characteristics. Therefore, also in this embodiment, the isolation characteristic can be improved without degrading the pass characteristic.

Note that the first ground wiring 28 and the second ground wiring 29 do not necessarily have to sandwich the input/output terminal side signal wiring 17B. It is sufficient that the input/output terminal side signal wiring 17B has a portion extending side by side with the first ground wiring 28 and a portion extending side by side with the second ground wiring 29. .

When the capacitance section C3 and the capacitance section C4 are provided in the second filter device 21B, the capacitance section C1 and the capacitance section C2 may not necessarily be provided in the first filter device 11A.

FIG. 12 is a circuit diagram of a composite filter device according to the fourth embodiment. FIG. 13 is a schematic plan view of a composite filter device according to a fourth embodiment;

As shown in FIG. 12, this embodiment differs from the third embodiment in that a capacitive section C5 and a capacitive section C6 are provided. One end of each of the capacitance section C5 and the capacitance section C6 is connected to the common connection terminal 12 . Capacitor C6 is included in first filter device 11A. Capacitor C5 is included in second filter device 21B. Except for the above points, the composite filter device 30 of this embodiment has the same configuration as the composite filter device of the third embodiment.

As shown in FIG. 13, in this embodiment, a third ground wiring 38 and a fourth ground wiring 39 are provided. More specifically, the third ground wiring 38 is connected to the parallel arm resonator P11 and the parallel arm resonator P13 of the second filter device 21B. The fourth ground wiring 39 is indirectly connected via the ground terminal 6 to the parallel arm resonator P2 of the first filter device 11A. The third ground wiring 38 and the fourth ground wiring 39 are connected to ground terminals 6 different from each other. The third ground wiring 38 and the fourth ground wiring 39 are arranged so as to sandwich the common connection terminal side signal wiring 17C. As described above, the common connection terminal side signal wiring 17C is a signal wiring connected to the common connection terminal 12 .

Returning to FIG. 12, the composite filter device 30 is provided with first to fourth sub-circuits similar to those of the third embodiment. Furthermore, in the composite filter device 30, a fifth sub-circuit including a capacitance section C5 is provided between the common connection terminal 12 and the parallel arm resonators P11 and P13. Furthermore, a sixth sub-circuit including a capacitance section C6 is provided between the common connection terminal 12 and the parallel arm resonator P2. As a result, isolation characteristics can be improved without deteriorating pass characteristics.

It should be noted that the third ground wiring 38 and the fourth ground wiring 39 do not necessarily have to sandwich the common connection terminal side signal wiring 17C. It is sufficient that the common connection terminal side signal wiring 17C has a portion extending side by side with the third ground wiring 38 and a portion extending side by side with the fourth ground wiring 39. .

When the capacitor C5 and the capacitor C6 are provided in the composite filter device 30, in the first filter device 11A and the second filter device 21B, the capacitor C1 and the capacitor C2 and the capacitor C3 and the capacitor The part C4 may not necessarily be provided. When the capacitive section C1 and the capacitive section C2 and the capacitive section C3 and the capacitive section C4 are not provided, each of the first filter device 11A and the second filter device 21B should have at least one ground terminal 6. . This allows the first filter device 11A to include the capacitance section C6 and the second filter device 11B to include the capacitance section C5. On the other hand, for example, a configuration in which the capacitance units C1 and C2 and the capacitance units C5 and C6 are provided and the capacitance units C3 and C4 are not provided may be employed. In this case, the first filter device 11A should have a plurality of ground terminals 6 and the second filter device 21B should have at least one ground terminal 6. FIG. Alternatively, for example, the first filter device 11A may include both the capacitive section C5 and the capacitive section C6.

It should be noted that one end of each of the fifth sub-circuit and the sixth sub-circuit does not necessarily have to be connected to the parallel arm resonator. At least one of the third ground wiring 38 and the fourth ground wiring 39 may be connected to the parallel arm resonator. Alternatively, at least one of the third ground wiring 38 and the fourth ground wiring 39 may not be connected to the parallel arm resonator. In this case, at least one of the third ground wiring 38 and the fourth ground wiring 39 should be connected to the ground terminal 6 that is not connected to the parallel arm resonator. Also in these cases, the isolation characteristics can be improved.

For example, in the modification of the fourth embodiment shown in FIG. 14, one end of each of the second sub-circuit, the third sub-circuit and the fifth sub-circuit is not connected to the parallel arm resonator. . That is, the capacitance section C2 of the first filter device 41A and the capacitance sections C3 and C5 of the second filter device 41B are not connected to the parallel arm resonator and are connected to the ground terminal 6. there is Note that the capacitance section C4 of the second filter device 41B is indirectly connected to the parallel arm resonator P11, the parallel arm resonator P13, the parallel arm resonator P14, and the parallel arm resonator P15 via the ground terminal 6. ing. Also in this modified example, the isolation characteristic can be improved without deteriorating the pass characteristic.

In the second to fourth embodiments, examples were shown in which the composite filter device was a duplexer. However, the composite filter device according to the invention may also be a multiplexer. As used herein, a multiplexer refers to a composite filter device having three or more filter devices and having the function of separating signals. The filter device may be a receive filter or a transmit filter. The filter device includes a notch filter. In the following an example is given where the composite filter device is a multiplexer.

FIG. 15 is a schematic diagram of a composite filter device according to the fifth embodiment.

The composite filter device 50 is a multiplexer. Composite filter device 50 has common connection terminal 12 and a plurality of filter devices. More specifically, the multiple filter devices of composite filter device 50 include first filter device 51A, second filter device 51B, third filter device 51C, and other filter devices. The number of filter devices in composite filter device 50 is not particularly limited. A plurality of filter devices share a common connection terminal 12 .

The first filter device 51A is a filter device according to the present invention. A composite filter device 50 need only comprise at least one filter device according to the invention. Also in the present embodiment, similarly to the second embodiment, etc., the isolation characteristics between the first filter device 51A and other filter devices can be improved without deteriorating the filter characteristics of the first filter device 51A. can be improved.

REFERENCE SIGNS LIST 1 filter device 3 input terminal 4 output terminal 5 piezoelectric substrate 6

ground terminals

7A, 7B input/output terminal

side signal wirings

8, 9 first and second ground wirings 10

composite filter device

11A, 11B First and second filter devices 12 Common connection terminal 14 Output terminal 17B Input/output terminal side signal wiring 17C Common connection terminal side signal wiring 21B

Second filter devices

28 and 29 First and second filter devices 2 ground wiring 30 ... composite filter devices 38, 39 ... third and fourth ground wiring 41A, 41B ... first and second filter devices 50 ... composite filter devices 51A to 51C ... first to third filter devices C: Capacitance elements C1 to C6: Capacitance units P1 to P3, P11 to P15: Parallel arm resonators S1 to S4, S11 to S17: Series arm resonators

Claims

an input terminal and an output terminal;
an input/output terminal side signal wiring connected to the input terminal or the output terminal;
at least one series arm resonator;
at least one parallel arm resonator;
a plurality of ground terminals;
a first ground wiring and a second ground wiring connected to the different ground terminals;
with
A filter device, wherein the input/output terminal side signal wiring has a portion that extends alongside and adjacent to the first ground wiring and a portion that extends alongside and adjacent to the second ground wiring.
2. The filter device according to claim 1, wherein said input/output terminal side signal wiring has a portion sandwiched between said first ground wiring and said second ground wiring.
3. The filter device according to claim 1, wherein at least one of said first ground wiring and said second ground wiring is connected to said parallel arm resonator.
comprising a plurality of parallel arm resonators,
the plurality of parallel arm resonators includes a first parallel arm resonator and a second parallel arm resonator;
4. The filter device according to claim 3, wherein said first ground wiring is connected to said first parallel arm resonator, and said second ground wiring is connected to said second parallel arm resonator. .
5. The filter device according to claim 4, wherein at least one said series arm resonator is connected between said first parallel arm resonator and said second parallel arm resonator.
3. The filter device according to claim 1, wherein at least one of said first ground wiring and said second ground wiring is connected to said ground terminal that is not connected to said parallel arm resonator.
comprising a plurality of filter devices sharing a common connection terminal,
A composite filter device, wherein at least one said filter device is a filter device according to any one of claims 1-6.
at least one filter device of the plurality of filter devices has a plurality of ground terminals, and at least one other filter device has at least one ground terminal;
a common connection terminal side signal wiring connected to the common connection terminal;
a third ground wiring and a fourth ground wiring connected to the different ground terminals;
further comprising
8. The signal wiring according to claim 7, wherein said common connection terminal side signal wiring has a portion that extends alongside and adjacent to said third ground wiring and a portion that extends alongside and adjacent to said fourth ground wiring. A composite filter device as described.
a first filter device and a second filter device sharing a common connection terminal and each having at least one series arm resonator, at least one parallel arm resonator, and at least one ground terminal;
a common connection terminal side signal wiring connected to the common connection terminal;
a third ground wiring and a fourth ground wiring connected to the different ground terminals;
with
The composite filter device according to claim 1, wherein the common connection terminal side signal wiring has a portion extending adjacently alongside the third ground wiring and a portion extending adjacently adjacent to the fourth ground wiring.
The composite filter device according to claim 9, wherein said first filter device is a transmit filter and said second filter device is a receive filter.
The composite filter device according to any one of claims 8 to 10, wherein at least one of said third ground wiring and said fourth ground wiring is connected to said parallel arm resonator.
11. The device according to any one of claims 8 to 10, wherein at least one of said third ground wiring and said fourth ground wiring is connected to said ground terminal not connected to said parallel arm resonator. composite filter device.