WO2023037925A1

WO2023037925A1 - Elastic wave filter and multiplexer

Info

Publication number: WO2023037925A1
Application number: PCT/JP2022/032490
Authority: WO
Inventors: 徹山路; 秀紀松井
Original assignee: 株式会社村田製作所
Priority date: 2021-09-08
Filing date: 2022-08-30
Publication date: 2023-03-16

Abstract

This elastic wave filter (1) comprises: a first filter circuit (10) provided to a first route (r1) linking a first terminal (T1) and a second terminal (T2); and an additional circuit (20) provided to a second route (r2) connected in parallel to the first route (r1). A longitudinally-coupled elastic wave resonator (25) of the additional circuit (20) has a plurality of IDT electrodes (31-34). Where a frequency calculated from the arrangement pitch (p) of electrode fingers (36) of the IDT electrodes (31, 33) connected toward the first terminal (T1) is fix, a frequency calculated from the arrangement pitch (p) of electrode fingers (36) of the IDT electrodes (32, 34) connected toward the second terminal (T2) is fox, the highest frequency in a passband of the first filter circuit (10) is fH1, and a prescribed frequency in an attenuation band of the first filter circuit (10) is fH2, the variables have the relationship wherein 1.055 × fH1 < fix and the relationship where 1.035 × fH1 < fox < fH2.

Description

Acoustic Wave Filters and Multiplexers

The present invention relates to an elastic wave filter and a multiplexer provided with this elastic wave filter.

Acoustic wave filters with acoustic wave resonators have been known. As an example of this type of acoustic wave filter, there is a filter circuit whose pass band is a predetermined frequency band, and a cancellation circuit having a canceling component of opposite phase and same amplitude as the above filter circuit in order to improve attenuation characteristics outside the pass band. and an elastic wave filter are disclosed (see Patent Documents 1 and 2). By providing the acoustic wave filter with the canceling circuit, it is possible to improve the attenuation characteristics and the like of the acoustic wave filter.

JP 2017-204743 A JP 2018-74539 A

However, the acoustic wave filter described in Patent Document 1 has a problem that the resonance frequency of the canceling circuit is far from the passband of the filter circuit, and the attenuation amount in the attenuation band of the filter circuit cannot be sufficiently secured.

In addition, the acoustic wave filter described in Patent Document 2 has a problem that the resonance frequency of the canceling circuit is too close to the passband of the filter circuit, and the power consumption of the acoustic wave filter increases. When the power consumption increases, the life of the acoustic wave filter may be shortened.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an acoustic wave filter or the like capable of ensuring attenuation in the attenuation band and reducing power consumption.

To achieve the above object, an elastic wave filter according to an aspect of the present invention provides a first terminal, a second terminal, and a first terminal provided on a first path connecting the first terminal and the second terminal. a filter circuit; and an additional circuit provided in a second path connected in parallel with at least part of the first path, the additional circuit having a longitudinally coupled elastic wave resonator, and the longitudinally coupled elastic wave resonator. The acoustic wave resonator has a plurality of IDT electrodes arranged along an acoustic wave propagation direction, and among the plurality of IDT electrodes, the first electrodes on the first terminal side when viewed from the longitudinally coupled acoustic wave resonator. Let fix be the frequency corresponding to the wavelength when the average pitch of the electrode fingers of the IDT electrodes connected to the path is 1/2 wavelength, Let fox be the frequency corresponding to the wavelength when the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side is set to 1/2 wavelength, and pass through the first filter circuit. If fH1 is the highest frequency in the band and fH2 is a predetermined frequency in the attenuation band located on the higher frequency side than the passband of the first filter circuit, then 1.055×fH1<fix. and 1.035×fH1<fox<fH2.

To achieve the above object, an elastic wave filter according to an aspect of the present invention provides a first terminal, a second terminal, and a first terminal provided on a first path connecting the first terminal and the second terminal. a filter circuit; and an additional circuit provided in a second path connected in parallel with at least part of the first path, the additional circuit having a longitudinally coupled elastic wave resonator, and the longitudinally coupled elastic wave resonator. The wave resonator has a plurality of IDT electrodes arranged along an elastic wave propagation direction, and the first filter circuit includes a plurality of other IDTs different from the plurality of IDT electrodes of the longitudinally coupled acoustic wave resonator. A piston mode is applied to at least some of the other plurality of IDT electrodes that are configured with electrodes and included in the first filter circuit, and a piston mode is applied to the plurality of IDT electrodes that are included in the additional circuit. not

To achieve the above object, an elastic wave filter according to an aspect of the present invention provides a first terminal, a second terminal, and a first terminal provided on a first path connecting the first terminal and the second terminal. a filter circuit; and an additional circuit provided in a second path connected in parallel with at least part of the first path, the additional circuit having a longitudinally coupled elastic wave resonator, and the longitudinally coupled elastic wave resonator. The wave resonator has a plurality of IDT electrodes arranged along an elastic wave propagation direction, and the first filter circuit includes a plurality of other IDTs different from the plurality of IDT electrodes of the longitudinally coupled acoustic wave resonator. Each of the other plurality of IDT electrodes included in the first filter circuit and the plurality of IDT electrodes included in the additional circuit, each of which is composed of electrodes, includes a pair of first comb-shaped electrodes and a second comb-like electrode. Each of the first comb-shaped electrode and the second comb-shaped electrode includes a bus bar electrode extending in the elastic wave propagation direction and a bus bar electrode connected to the bus bar electrode and perpendicular to the elastic wave propagation direction. a plurality of intersecting electrode fingers and a plurality of offset electrode fingers extending in orthogonal directions, wherein the intersecting electrode fingers of the first comb-shaped electrode and the offset electrode fingers of the second comb-shaped electrode are The intersecting electrode fingers of the second comb-shaped electrode and the offset electrode fingers of the first comb-shaped electrode, which are opposed to each other in the orthogonal direction, are opposed to each other in the orthogonal direction, and are arranged in the additional circuit. A space between the intersecting electrode fingers and the offset electrode fingers facing each other in the orthogonal direction is wider than a space between the intersecting electrode fingers and the offset electrode fingers facing each other in the orthogonal direction in the first filter circuit.

In order to achieve the above object, the multiplexer according to one aspect of the present invention is characterized in that the predetermined frequency within the attenuation band is the highest frequency of the pass band of the second filter circuit different from the first filter circuit. a wave filter and another filter comprising the second filter circuit.

To achieve the above object, an elastic wave filter according to an aspect of the present invention provides a first terminal, a second terminal, and a first terminal provided on a first path connecting the first terminal and the second terminal. a filter circuit; and an additional circuit provided in a second path connected in parallel with at least part of the first path, the additional circuit having a longitudinally coupled elastic wave resonator, and the longitudinally coupled elastic wave resonator. The acoustic wave resonator has a plurality of IDT electrodes arranged along an acoustic wave propagation direction, and among the plurality of IDT electrodes, the first electrodes on the first terminal side when viewed from the longitudinally coupled acoustic wave resonator. Let fiy be the frequency corresponding to the wavelength when the average pitch of the electrode fingers of the IDT electrodes connected to the path is 1/2 wavelength, and the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side is assumed to be 1/2 wavelength, and the frequency corresponding to the wavelength is foy, and the frequency passing through the first filter circuit is foy. If fL3 is the lowest frequency of the band and fL4 is a predetermined frequency in the attenuation band located on the lower frequency side than the pass band of the first filter circuit, then there is a relationship of fiy<0.945×fL3. and fL4<foy<0.965×fL3.

To achieve the above object, the multiplexer according to one aspect of the present invention is characterized in that the predetermined frequency within the attenuation band is the lowest frequency of the pass band of the second filter circuit different from the first filter circuit. a wave filter and another filter comprising the second filter circuit.

According to the acoustic wave filter and the like according to the present invention, it is possible to secure the attenuation amount in the attenuation band and reduce the power consumption.

FIG. 1 is a circuit configuration diagram of a multiplexer having an elastic wave filter according to Embodiment 1. FIG. FIG. 2 is a diagram showing the layout of each element included in the multiplexer according to the first embodiment. FIG. 3 is a diagram showing passbands and attenuation bands of the elastic wave filter according to Embodiment 1. FIG. FIG. 4 is a diagram schematically showing a state in which each element of the acoustic wave filter according to Embodiment 1 is provided on the piezoelectric substrate and the package substrate. FIG. 5 is a diagram showing an additional circuit of the acoustic wave filter according to Embodiment 1. FIG. FIG. 6 is a plan view and a cross-sectional view schematically showing the structure of a longitudinally coupled acoustic wave resonator included in the additional circuit. FIG. 7 is a diagram showing power consumption of the acoustic wave filter of Embodiment 1. FIG. FIG. 8 is a diagram showing the power consumption of the acoustic wave filter when the frequency ratio on the input side of the longitudinally coupled acoustic wave resonator is changed. FIG. 9 is a diagram showing the power consumption of the acoustic wave filter when the frequency ratio on the output side of the longitudinally coupled acoustic wave resonator is changed. FIG. 10 is a diagram showing the power consumption of the acoustic wave filter when changing the frequency ratio between the input side and the output side of the longitudinally coupled acoustic wave resonator. FIG. 11 is a diagram showing power consumption when the number of reflectors in the additional circuit of the elastic wave filter according to Modification 1 of Embodiment 1 is changed. 12A and 12B are a plan view and a cross-sectional view of an IDT electrode included in a first filter circuit of an acoustic wave filter according to Modification 2 of Embodiment 1. FIG. 13A and 13B are a plan view and a cross-sectional view of an IDT electrode included in an additional circuit of an elastic wave filter according to Modification 2 of Embodiment 1. FIG. FIG. 14 is a diagram showing another example of IDT electrodes included in the first filter circuit. FIG. 15 is a diagram showing another example of IDT electrodes included in the first filter circuit. FIG. 16 is a diagram showing another example of IDT electrodes included in the first filter circuit. FIG. 17 is a diagram showing the withstand power of the elastic wave filter according to Modification 2 of Embodiment 1. FIG. 18 is a plan view showing an IDT electrode included in the first filter circuit of the acoustic wave filter according to Modification 3 of Embodiment 1. FIG. 19 is a plan view showing an IDT electrode included in an additional circuit of an acoustic wave filter according to Modification 3 of Embodiment 1. FIG. 20 is a cross-sectional view showing a dielectric layer formed on the IDT electrodes of the first filter circuit and the additional circuit of the elastic wave filter according to Modification 4 of Embodiment 1. FIG. 21 is a circuit configuration diagram of a multiplexer including an elastic wave filter according to Modification 5 of Embodiment 1. FIG. FIG. 22 is a circuit configuration diagram of a multiplexer including an acoustic wave filter according to Embodiment 2. FIG. FIG. 23 is a diagram showing passbands and attenuation bands of the elastic wave filter according to the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail using embodiments and drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection forms, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. Among the constituent elements in the following embodiments, constituent elements not described in independent claims will be described as optional constituent elements. Also, the sizes, or size ratios, of components shown in the drawings are not necessarily exact. Moreover, in each figure, the same code|symbol is attached|subjected with respect to substantially the same structure, and the overlapping description may be abbreviate|omitted or simplified. In the following embodiments, "connected" includes not only direct connection but also electrical connection via other elements.

(Embodiment 1)
[Overview of the present invention]
An overview of the present invention will be described with reference to FIGS. 1 to 3. FIG.

FIG. 1 is a circuit configuration diagram of a multiplexer 5 including an acoustic wave filter 1 according to Embodiment 1. FIG. FIG. 2 is a diagram showing the layout of each element included in the multiplexer 5. As shown in FIG.

The multiplexer 5 is a demultiplexer or multiplexer with multiple filters. The multiplexer 5 includes an elastic wave filter 1 having a first filter circuit 10 and an additional circuit 20 and a second filter circuit 50 . Further, the multiplexer 5 is connected to the first terminal T1 connected to the elastic wave filter 1, the second terminal T2 connected to both the elastic wave filter 1 and the second filter circuit 50, and the second filter circuit 50. and a third terminal T3.

The first terminal T1 is a terminal on the signal input side of the acoustic wave filter 1. For example, the first terminal T1 is connected to an RF signal processing circuit (not shown) via an amplifier circuit or the like (not shown).

The second terminal T2 is a terminal on the signal output side of the acoustic wave filter 1, and a terminal on the signal input side of the second filter circuit 50. That is, the second terminal T2 is a common terminal of the acoustic wave filter 1 and the second filter circuit 50. FIG. The second terminal T2 has a node n0 between the elastic wave filter 1 and the second terminal T2 as a branch point, one branched path is connected to the elastic wave filter 1, and the other branched path is the second filter circuit. 50. For example, the second terminal T2 is connected to an antenna element (not shown).

The third terminal T3 is a signal output side terminal of the second filter circuit 50 . For example, the third terminal T3 is connected to an RF signal processing circuit (not shown) via an amplifier circuit or the like (not shown).

The elastic wave filter 1 is arranged on the first route r1 connecting the first terminal T1 and the second terminal T2. The acoustic wave filter 1 includes a first filter circuit 10 and an additional circuit 20 additionally connected to the first filter circuit 10 . A high-frequency signal input to the first terminal T1 is output from the second terminal T2 through the parallel-connected first path r1 and second path r2.

The first filter circuit 10 is a filter circuit having a passband of a predetermined frequency band defined by communication standards. The elastic wave filter 1 including the first filter circuit 10 is, for example, a transmission filter whose passband is the upstream frequency band (transmission band), and is set so that the passband is lower than that of the second filter circuit 50 .

The additional circuit 20 is a canceling circuit having a canceling component of the opposite phase and the same amplitude as the first filter circuit 10 in order to improve the attenuation characteristics outside the passband of the first filter circuit 10 . The additional circuit 20 is provided on a second route r2 connected in parallel to at least part of the first route r1. The additional circuit 20 has a longitudinally coupled acoustic wave resonator 25. The longitudinally coupled acoustic wave resonator 25 comprises a plurality of IDT (InterDigital Transducer)

electrodes

31, 32, 33 and 34 arranged along the acoustic wave propagation direction. have. A high-frequency signal transmitted through the second path r2 is input to the

IDT electrodes

31 and 33 and output from the IDT electrodes 32 and .

The second filter circuit 50 is arranged on a third route r3 connecting the second terminal T2 and the third terminal T3. The second filter circuit 50 has a passband that is different from the passband of the first filter circuit 10 . The second filter circuit 50 is, for example, a reception filter whose passband is the downlink frequency band (reception band). The second filter circuit 50 includes, for example, a series arm resonator S21, a plurality of parallel arm resonators P21 and P22, and an elastic wave resonator Q21.

The multiplexer 5, for example, Band 8 (transmitting band: 880 MHz-915 MHz, receiving band: 925 MHz-960 MHz) or Band 3 (transmitting band: 1710 MHz-1785 MHz, receiving band: 1805 MHz-1880 MHz) High frequency signal is input and output. .

The elastic wave filter 1 of the present embodiment has the configuration shown below in order to secure the attenuation amount in the attenuation band and to reduce the power consumption.

FIG. 3 is a diagram showing the passband and attenuation band of the acoustic wave filter 1. FIG. The figure also shows the pass band of the second filter circuit 50 .

FIG. 3 shows the lowest frequency fL1 and the highest frequency fH1 of the passband of the first filter circuit 10. FIG. FIG. 3 also shows the predetermined frequency fH2 of the attenuation band located on the higher frequency side than the pass band of the first filter circuit 10. As shown in FIG. The predetermined frequency fH2 is, for example, the highest frequency of the passband of the second filter circuit 50 . A frequency fL2 within the attenuation band in the figure is, for example, the lowest frequency of the passband of the second filter circuit 50 .

Here, the frequency corresponding to the wavelength of the elastic wave when the total average of the arrangement pitch of the electrode fingers of the plurality of IDT electrodes 31 to 34 of the longitudinally coupled acoustic wave resonator 25 is 1/2 wavelength (λ/2) is Define fx. The arrangement pitch of the electrode fingers is the center-to-center distance between two adjacent electrode fingers in the elastic wave propagation direction. A frequency corresponding to a wavelength is calculated by dividing the speed of sound by the wavelength. The frequency corresponding to the wavelength can also be derived as the resonance frequency by contacting a measurement probe to each IDT electrode and measuring the reflection characteristics.

Further, among the plurality of IDT electrodes 31 to 34, the average arrangement pitch of the electrode fingers of the

IDT electrodes

31 and 33 connected to the first path r1 on the first terminal T1 side when viewed from the longitudinally coupled acoustic wave resonator 25 is A frequency corresponding to a wavelength of 1/2 wavelength (λ/2) is defined as fix. Further, among the plurality of IDT electrodes 31 to 34, the average arrangement pitch of the electrode fingers of the

IDT electrodes

32 and 34 connected to the first path r1 on the second terminal T2 side when viewed from the longitudinally coupled acoustic wave resonator 25 is A frequency corresponding to a wavelength of 1/2 wavelength (λ/2) is defined as fox.

Under these definitions, the elastic wave filter 1 according to the present embodiment is
(1) 1.055×fH1<fix, and
(2) 1.035×fH1<fox<fH2
It has a relationship of According to this configuration, the attenuation in the attenuation band of the acoustic wave filter 1 can be ensured, and power consumption can be reduced.

For example, as shown by 1.055×fH1<fix in (1) and 1.035×fH1<fox in (2), frequency fix and frequency fox are not too close to the passband of elastic wave filter 1. By setting the power consumption higher than necessary, it is possible to prevent the power consumption from increasing more than necessary. Further, as indicated by fox<fH2 in (2), the attenuation amount in the attenuation band can be ensured by making the frequency fox lower than the predetermined frequency fH2 and within the attenuation band. In order to prevent the frequency fix and the frequency fox from being too far apart, the frequency fx calculated from the overall average of the arrangement pitches of the electrode fingers of the IDT electrodes 31 to 34 is preferably fx≦1.15×fH1. . A specific configuration of the acoustic wave filter 1 will be described below.

[Configuration of elastic wave filter]
As described above, the elastic wave filter 1 has the first filter circuit 10 and the additional circuit 20 . First, the first filter circuit 10 of the acoustic wave filter 1 will be described with reference to FIGS. 1 to 4. FIG.

As shown in FIG. 1, the first filter circuit 10 includes series arm resonators S11, S12, S13, S14 and S15 and parallel arm resonators P11, P12, P13 and P14, which are elastic wave resonators.

The series arm resonators S11 to S15 are arranged on a first path r1 connecting the first terminal T1 and the second terminal T2. The series arm resonators S11 to S15 are connected in series in this order from the first terminal T1 toward the second terminal T2.

The parallel arm resonators P11 to P14 are arranged on a path connecting each node n1, n2, n3, n4 between the series arm resonators S11 to S15 arranged on the first path r1 and the ground (reference terminal). there is Specifically, among the parallel arm resonators P11 to P14, the parallel arm resonator P11 closest to the series arm resonator S11 has one end connected to the node n1 between the series arm resonators S11 and S12. , and the other end is connected to the ground via an inductor L11. The parallel arm resonator P11 is composed of two resonators connected in parallel, that is, two divided resonators. The parallel arm resonator P12 has one end connected to a node n2 between the series arm resonators S12 and S13, and the other end connected to the ground via the inductor L11. The parallel arm resonator P13 has one end connected to a node n3 between the series arm resonators S13 and S14, and the other end connected to the ground via the inductor L12. The parallel arm resonator P14 has one end connected to a node n4 between the series arm resonators S14 and S15, and the other end connected to the ground via the inductor L12.

The other ends of the parallel arm resonators P11 and P12 are made common by wire connection and connected to the inductor L11, and the other ends of the parallel arm resonators P13 and P14 are made common by wire connection and connected to the inductor L12. It is Each element of these elastic wave filters 1 is provided on the piezoelectric substrate 320 and the package substrate 330 .

FIG. 4 is a diagram showing a state in which each element of the acoustic wave filter 1 is provided on the piezoelectric substrate 320 and the package substrate 330. FIG. Note that FIG. 4 also shows the multiplexer 5 including the elastic wave filter 1 and the second filter circuit 50 .

The piezoelectric substrate 320 is the substrate on which the main part of the multiplexer 5 is provided. The piezoelectric substrate 320 is provided with the series arm resonators S11 to S15, the parallel arm resonators P11 to P14, the additional circuit 20, and the second filter circuit 50 described above. Further, the piezoelectric substrate 320 is provided with a meandering resistance element R13 (see FIG. 2). The resistance element R13 is provided on a path connecting the parallel arm resonator P14 and the parallel arm resonator P21 of the second filter circuit 50. As shown in FIG.

The package substrate 330 is a substrate on which the piezoelectric substrate 320 is mounted. The package substrate 330 is provided with the inductors L11 and L12 described above.

As shown in FIGS. 1 and 4, the first filter circuit 10 includes five series arm resonators S11 to S15 arranged on a first path r1 and It has a π-type ladder filter structure composed of four parallel arm resonators P11 to P14. The number of series arm resonators and parallel arm resonators constituting the first filter circuit 10 is not limited to five or four, and the number of series arm resonators is one or more and the number of parallel arm resonators is one or more. If it is Also, an inductor may be provided between the parallel arm resonator and the ground.

Next, the additional circuit 20 of the acoustic wave filter 1 will be described with reference to FIGS. 1 and 5. FIG. The additional circuit 20 is a circuit that suppresses the unwanted waves from being output from the elastic wave filter 1 by applying an opposite phase to the unwanted waves outside the passband of the first filter circuit 10 .

As shown in FIG. 1, the additional circuit 20 is provided on a second route r2 that is connected in parallel to at least part of the first route r1. For example, the additional circuit 20 is connected to multiple nodes on the first route r1.

FIG. 5 is a diagram showing the additional circuit 20 of the elastic wave filter 1. FIG.

The longitudinally coupled acoustic wave resonator 25 of the additional circuit 20 shown in FIG. 5 has a plurality of

IDT electrodes

31, 32, 33 and . A plurality of

IDT electrodes

31, 32, 33, 34 are arranged in this order along the elastic wave propagation direction d1.

Also, the additional circuit 20 has a plurality of

reflectors

41 and 42 . The plurality of

reflectors

41 and 42 are positioned on both outer sides of the IDT electrodes 31 to 34 so as to sandwich the plurality of IDT electrodes 31 to 34 in the elastic wave propagation direction d1.

Among the plurality of IDT electrodes 31 to 34, the

IDT electrodes

31 and 33 are connected to the first path r1 on the first terminal T1 side when viewed from the longitudinally coupled acoustic wave resonator 25. The

IDT electrodes

32 and 34 are connected to the first path r1 on the second terminal T2 side when viewed from the longitudinally coupled acoustic wave resonator 25 . In other words, the

IDT electrodes

31 and 33 are connected to the first path r1 on the first terminal T1 side when viewed from the series arm resonators S14 and S15 connected in parallel to the longitudinally coupled acoustic wave resonator 25, and the

IDT electrodes

32 , 34 are connected to the first path r1 on the second terminal T2 side as viewed from the series arm resonators S14 and S15.

The second path r2 has two partial paths r21 and r23 connected to the first terminal T1 side when viewed from the longitudinally coupled acoustic wave resonator 25. A partial path r21 is a path connecting the ground and the node n3, and a partial path r23 is a path connecting the ground and the node n2. A capacitive element C10 is provided on a route connecting the partial route r21 and the partial route r23. An IDT electrode 31 is arranged on the partial route r21, and an IDT electrode 33 is arranged on the partial route r23.

Also, the second path r2 has two partial paths r22 and r24 connected to the second terminal T2 side when viewed from the longitudinally coupled acoustic wave resonator 25 . A partial path r22 is a path connecting the ground and the node n5, and a partial path r24 is a path connecting the ground and the node n5. An IDT electrode 32 and a capacitive element C2 are arranged on the partial route r22, and an IDT electrode 34 and a capacitive element C4 are arranged on the partial route r24.

Note that the node n5 is a node located on the path connecting the node n0 and the series arm resonator S15. Node n5 may be the same as node n0. The partial paths r22 and r24 may be connected and connected to the node n5, or may be connected to the node n5 respectively without being connected.

In the above example, partial route r21 is connected to node n3, partial route r23 is connected to node n2, and partial routes r22 and r24 are connected to node n5, but the present invention is not limited to this. Each of the partial paths r21, r23 and the partial paths r22, r24 may be connected to both outer nodes of the one or more series arm resonators arranged on the first path r1. For example, partial paths r21 and r23 may be connected to node n1, or may be connected to a node on first path r1 connecting first terminal T1 and series arm resonator S11. For example, partial paths r22 and r24 may be connected to node n4.

[Structure of longitudinally coupled acoustic wave resonator included in additional circuit]
The structure of the longitudinally coupled acoustic wave resonator 25 included in the additional circuit 20 will be described with reference to FIGS. 5 and 6. FIG. The longitudinally coupled acoustic wave resonator 25 is composed of, for example, a plurality of SAW (Surface Acoustic Wave) resonators.

6A and 6B are a plan view and a cross-sectional view schematically showing the structure of the longitudinally coupled acoustic wave resonator 25 included in the additional circuit 20. FIG. Note that the longitudinally coupled acoustic wave resonator 25 shown in FIG. 6 is for explaining a typical structure of the resonator, and the number and length of the electrode fingers included in the IDT electrodes and reflectors, etc. is not limited to this.

The longitudinally coupled acoustic wave resonator 25 is composed of a piezoelectric substrate 320 having piezoelectricity and a plurality of IDT electrodes 31 to 34 formed on the piezoelectric substrate 320 . A plurality of

reflectors

41 and 42 are provided on both sides of the longitudinally coupled acoustic wave resonator 25 in the acoustic wave propagation direction d1.

As shown in the cross-sectional view of FIG. 6, the longitudinally coupled acoustic wave resonator 25 and the electrodes of the plurality of

reflectors

41 and 42 constitute the piezoelectric substrate 320, the IDT electrodes 31-34 and the electrodes of the

reflectors

41 and 42. and a dielectric layer 326 provided on the piezoelectric substrate 320 to cover the IDT electrodes 31-34 and the reflectors 41 and .

The piezoelectric substrate 320 is, for example, a LiNbO ₃ substrate (lithium niobate substrate) with a cut angle of 127.5°. When Rayleigh waves are used as elastic waves propagating in the piezoelectric substrate 320, the cut angle of the piezoelectric substrate 320 is desirably 120°±20° or 300°±20°.

The electrode layer 325 has a structure in which a plurality of metal layers are laminated. The electrode layer 325 is formed by stacking, for example, a Ti layer, an Al layer, a Ti layer, a Pt layer, and a NiCr layer in this order from the top.

The dielectric layer 326 is, for example, a film whose main component is silicon dioxide (SiO ₂ ). The dielectric layer 326 is provided for the purpose of adjusting the frequency-temperature characteristics of the longitudinally coupled acoustic wave resonator 25, protecting the electrode layer 325 from the external environment, or increasing moisture resistance. For example, the dielectric layer 326 may be formed so that the series arm resonators S11 to S15 are thicker than the parallel arm resonators P11 to P14. The dielectric layer 326 has the same thickness for the series arm resonator having the highest antiresonance frequency among the series arm resonators S11 to S15 and the IDT electrodes 31 to 34 of the longitudinally coupled acoustic wave resonator 25. It may be formed so as to be

As shown in the plan view of FIG. 6, each of the IDT electrodes 31-34 has a comb shape. The IDT electrode 31 has a pair of a first comb-shaped electrode 31a and a second comb-shaped electrode 31b. The IDT electrode 32 has a pair of a first comb-shaped electrode 32a and a second comb-shaped electrode 32b. The IDT electrode 33 has a pair of a first comb-shaped electrode 33a and a second comb-shaped electrode 33b. The IDT electrode 34 has a pair of a first comb-shaped electrode 34a and a second comb-shaped electrode 34b.

The first comb-shaped electrode 31a is connected to the node n3 through the partial route r21, and the first comb-shaped electrode 33a is connected to the node n2 through the partial route r23. The first comb-shaped electrode 32a is connected to the node n5 through the partial route r22, and the first comb-shaped electrode 34a is connected to the node n5 through the partial route r24. Each of the second comb-shaped

electrodes

31b, 32b, 33b, and 34b is connected to the ground.

Each of the first comb-shaped electrodes 31a to 34a includes a busbar electrode 37a extending in the elastic wave propagation direction d1 and a plurality of electrode fingers 36a connected to the busbar electrode 37a and extending in the orthogonal direction d2 orthogonal to the elastic wave propagation direction d1. and Each of the second comb-shaped electrodes 31b to 34b has a busbar electrode 37b extending in the acoustic wave propagation direction d1 and a plurality of electrode fingers 36b connected to the busbar electrode 37b and extending in the orthogonal direction d2. The plurality of

electrode fingers

36a and 36b are interposed in the orthogonal direction d2 and face the elastic wave propagation direction d1. Hereinafter, both the

electrode fingers

36a and 36b may be referred to as the electrode finger 36 in some cases.

The resonance frequencies of the IDT electrodes 31 to 34 can be adjusted, for example, by changing the arrangement pitch p, which is the distance between the centers of the electrode fingers 36 adjacent to each other in the elastic wave propagation direction d1. For example, the arrangement pitch p of the electrode fingers 36 of the IDT electrode 31 is obtained by dividing the center-to-center distance between the two electrode fingers located at the outermost ends of the IDT electrode 31 by (the number of electrode fingers 36 of the IDT electrode 31 -1). Calculated by In the present embodiment, by setting the arrangement pitch p of the electrode fingers 36 to a predetermined condition, an increase in the power consumption of the elastic wave filter 1 is suppressed.

[Electric Wave Filter Power Consumption]
Power consumption of the elastic wave filter 1 will be described with reference to FIGS. 7 to 10. FIG. In the following, the elastic wave filter 1 of the multiplexer 5 to which the high frequency signal of Band 8 is input/output will be described as an example.

FIG. 7 is a diagram showing the power consumption of the elastic wave filter 1. FIG. The power consumption shown in this figure and the following figures is the power consumption per unit area. □ in “mW/□”, which is the unit of power consumption, means logarithm×intersection width.

(a) of FIG. 7 shows the power consumption of the elastic wave filter 1 when a power of 29 dBm is input to the elastic wave filter 1 . The broken-line waveform in the figure is the power consumption of the elastic wave filter 1 of the first comparative example, and the solid-line waveform is the power consumption of the elastic wave filter 1 of the first embodiment. The figure also shows the lowest frequency fL1 and the highest frequency fH1 of the passband of the acoustic wave filter 1. FIG.

(b) of FIG. 7 shows the electrode parameters of the IDT electrode of the additional circuit 20 of the elastic wave filter 1 of Comparative Example 1, and (c) of FIG. Electrode parameters for 20 IDT electrodes are shown.

(b) and (c) of FIG. 7 show, as electrode parameters, the logarithm of the IDT electrodes 31 to 34, the wavelength λ, the arrangement pitch p of the electrode fingers 36, and the like. The wavelength λ of the IDT electrodes 31 to 34 corresponds to twice the arrangement pitch p of the electrode fingers 36 . The IDT electrodes 31 to 34 have a duty of 0.5 and an intersection width of 17.5λ.

The figure also shows the frequency ratio corresponding to each of the IDT electrodes 31-34. Each frequency ratio has the highest frequency fH1 (915 MHz in this example) of the passband as the denominator, and the frequency corresponding to the wavelength when the arrangement pitch p of the electrode fingers 36 of the IDT electrodes 31 to 34 is 1/2 wavelength. is the value when is the numerator. The frequency corresponding to the wavelength is calculated by dividing the speed of sound (3506 m/s in this example) by the wavelength.

The figure shows the input-side frequency ratio (fix/fH1), which is the frequency ratio of the

IDT electrodes

31 and 33 to which high-frequency signals are input. The figure also shows the output-side frequency ratio (fox/fH1), which is the frequency ratio of the

IDT electrodes

32 and 34 that output high-frequency signals. Note that the frequency fix is a frequency corresponding to the wavelength when the average of the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 is 1/2 wavelength, and the frequency fox is the frequency corresponding to the electrode fingers of the

IDT electrodes

32 and 34. It is the frequency corresponding to the wavelength when the average of the arrangement pitch p of 36 is set to 1/2 wavelength.

When the values shown in (b) and (c) of FIG. 7 are used, the frequency ratio on the input side is (frequency ratio of IDT electrode 31×logarithm of IDT electrode 31/sum of logarithms of IDT electrodes 31 and 33). +(Frequency ratio of IDT electrode 33×logarithm of IDT electrode 33/sum of logarithms of IDT electrodes 31 and 33). The frequency ratio on the output side is (frequency ratio of IDT electrode 32×logarithm of IDT electrode 32/sum of logarithms of IDT electrodes 32 and 34)+(frequency ratio of IDT electrode 34×logarithm of IDT electrode 34/

IDT electrode

32, 34 logarithms).

As shown in FIG. 7A, in Example 1, the excitation response of the longitudinally coupled acoustic wave resonator 25 having the IDT electrodes 31 to 34 is higher than the passband of the acoustic wave filter 1, that is, the power It is located on the high frequency side of the injection point. As a result, the elastic wave filter 1 according to the first embodiment can reduce the power consumption at the power input point.

In addition, in the acoustic wave filter 1 of Example 1, the power consumption is smaller than that of the acoustic wave filter 1 of Comparative Example 1 in 900 MHz to 915 MHz, which is part of the passband. Therefore, the difference in power consumption due to the difference in the electrode parameters of the IDT electrodes 31 to 34 will be further described.

FIG. 8 is a diagram showing power consumption of the acoustic wave filter 1 when the frequency ratio on the input side of the longitudinally coupled acoustic wave resonator 25 is changed. The power consumption shown in this figure and the following figures is the power consumption at the highest frequency fH1 of the passband.

The figure shows the power consumption when the frequency ratio (fox/fH1) on the output side of the longitudinally coupled acoustic wave resonator 25 is fixed at 1.036 and the frequency ratio (fix/fH1) on the input side is changed. It is The logarithm, duty and intersection width of the IDT electrodes 31 to 34 are the same as in FIG. 7(c). In the following evaluation, power consumption of about 5.00E ⁻³ dBm was assumed to be low enough to prevent failures such as disconnection.

As shown in FIG. 8, the acoustic wave filter 1 consumes a large amount of power when the frequency ratio on the input side of the longitudinally coupled acoustic wave resonator 25 is 1.044, and consumes a large amount of power when the frequency ratio is 1.055 and 1.066. is getting smaller. That is, in the elastic wave filter 1, power consumption is reduced by setting the frequency fix calculated from the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 on the input side to a relationship of 1.055×fH1<fix. can be made smaller.

FIG. 9 is a diagram showing power consumption of the acoustic wave filter 1 when the frequency ratio on the output side of the longitudinally coupled acoustic wave resonator 25 is changed.

The figure shows the power consumption when the frequency ratio (fix/fH1) on the input side of the longitudinally coupled acoustic wave resonator 25 is fixed at 1.055 and the frequency ratio (fix/fH1) on the output side is changed. It is The logarithm, duty and intersection width of the IDT electrodes 31 to 34 are the same as in FIG. 7(c).

As shown in FIG. 9, the acoustic wave filter 1 consumes a large amount of power when the frequency ratio on the output side of the longitudinally coupled acoustic wave resonator 25 is 1.033, and consumes a large amount of power when the frequency ratio is 1.036 and 1.04. is getting smaller. That is, in the elastic wave filter 1, power consumption is reduced by setting the frequency fox calculated from the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

32 and 34 on the output side to satisfy the relationship of 1.036×fH1<fox. can be made smaller.

FIG. 10 is a diagram showing power consumption of the acoustic wave filter 1 when the frequency ratio between the input side and the output side of the longitudinally coupled acoustic wave resonator 25 is changed.

In the figure, the total value of the frequency ratio on the input side and the frequency ratio on the output side of the longitudinally coupled acoustic wave resonator 25 is 2.09 (=1.055+1.035), and the frequency ratio on the input side and the output side is The power consumption when the value is changed is shown. Note that the horizontal axis of FIG. 10 indicates the frequency ratio on the input side. The duty and crossing width of the IDT electrodes 31 to 34 are the same as in FIG. 7(c). The logarithm of the IDT electrodes 31 to 34 is 8.5, and the values are the same. The frequency fx calculated from the total average of the arrangement pitches p of the electrode fingers of the IDT electrodes 31 to 34 is smaller than 1.15 times the frequency fH1 (fx<1.15×fH1).

As shown in FIG. 10, in the elastic wave filter 1, when "frequency ratio on the input side = 1.035 (frequency ratio on the output side = 1.056)" and "frequency ratio on the input side = 1.044 (output frequency ratio = 1.056)" side frequency ratio=1.047)”, there is almost no change in power consumption. On the other hand, if the frequency ratio on the input side is made larger than that on the output side, and the frequency ratio on the input side is 1.055 (the frequency ratio on the output side is 1.036), the power consumption of the acoustic wave filter 1 is reduced. It's getting smaller. That is, in the elastic wave filter 1, the power consumption can be reduced by setting the frequency fix and the frequency fox in a relationship of fox<fix.

[Modification 1 of Embodiment 1]
An acoustic wave filter 1A of Modification 1 of Embodiment 1 will be described. In Modification 1, the case where the number of electrode fingers of the

reflectors

41 and 42 of the additional circuit 20 is changed will be described.

FIG. 11 is a diagram showing power consumption when changing the number of electrode fingers of the

reflectors

41 and 42 of the additional circuit 20 of the acoustic wave filter 1A according to Modification 1. FIG.

In the figure, the frequency ratio (fox/fH1) on the output side of the longitudinally coupled acoustic wave resonator 25 is fixed at 1.036, the frequency ratio (fix/fH1) on the input side is fixed at 1.055, and the reflection Power consumption is shown when the number of electrode fingers of the

devices

41 and 42 is changed. Although the case where the number of electrode fingers of one reflector 41 is changed will be described below, the number of electrode fingers of the other reflector 42 is similarly changed. The logarithm, duty and intersection width of the IDT electrodes 31 to 34 are the same as in FIG. 7(c).

As shown in FIG. 11, the acoustic wave filter 1A consumes less power when the number of electrode fingers of the reflector 41 is 6 and 10, and increases when the number of electrode fingers is 15 or more. That is, in the elastic wave filter 1A, the number of electrode fingers of each of the plurality of

reflectors

41 and 42 is reduced, specifically, to 10 or less, thereby reducing multiple reflection of the

reflectors

41 and 42, thereby reducing the IDT. The excitation of the electrodes 31-34 can be weakened. Thereby, the power consumption of the elastic wave filter 1A can be reduced.

[Modification 2 of Embodiment 1]
An elastic wave filter 1B according to Modification 2 of Embodiment 1 will be described with reference to FIGS. 12 to 16. FIG. In Modified Example 2, the piston mode is applied to the IDT electrode 61 of the first filter circuit 10 and the IDT electrodes 31 to 34 of the additional circuit 20 are not applied to the piston mode.

12A and 12B are a plan view and a cross-sectional view of an IDT electrode included in the first filter circuit 10 of the acoustic wave filter 1B according to Modification 2. FIG. An IDT electrode 61 forming an elastic wave resonator of the first filter circuit 10 is shown.

As shown in FIG. 12, the IDT electrode 61 included in the first filter circuit 10 has a pair of a first comb-shaped electrode 61a and a second comb-shaped electrode 61b. The first comb-shaped electrode 61a has a busbar electrode 67a extending in the elastic wave propagation direction d1 and a plurality of electrode fingers 66a connected to the busbar electrode 67a and extending in the orthogonal direction d2. The second comb-shaped electrode 61b has a busbar electrode 67b extending in the elastic wave propagation direction d1 and a plurality of electrode fingers 66b connected to the busbar electrode 67b and extending in the orthogonal direction d2. The plurality of

electrode fingers

66a and 66b are interposed in the orthogonal direction d2 and face the elastic wave propagation direction d1.

In modification 2, the piston mode is applied to this IDT electrode 61 . In the example shown in FIG. 12, the piston mode is applied to the IDT electrode 61 by forming the load film 62 on each of the

electrode fingers

66a and 66b. The load films 62 are electrodes that serve as weights for the

electrode fingers

66a and 66b, and are provided at the tips and centers of the

electrode fingers

66a and 66b. For example, the center of the electrode finger 66a is a portion excluding both ends (root and tip) of the electrode finger 66a in the extending direction of the electrode finger 66a.

13A and 13B are a plan view and a cross-sectional view of an IDT electrode included in the additional circuit 20 of the elastic wave filter 1B. FIG. 13 shows the IDT electrodes 31 to 34 forming the longitudinally coupled acoustic wave resonator 25 of the additional circuit 20. As shown in FIG.

The piston mode is not applied to the IDT electrodes 31-34 included in the additional circuit 20. Specifically, as shown in FIG. 13, the load film 62 is not formed on the electrode fingers 36 of the IDT electrodes 31 to 34, and the electrode fingers 36 have the same thickness along the orthogonal direction d2.

In modification 2, the piston mode is applied to at least some of the IDT electrodes 61 included in the first filter circuit 10, but the piston mode is applied to the plurality of IDT electrodes 31 to 34 included in the additional circuit 20. It has not been. With this configuration, it is possible to prevent excessive energy from being trapped in the IDT electrodes 31 to 34 and reduce the power applied to the IDT electrodes 31 to 34 . As a result, shortening of the life of the elastic wave filter 1B can be suppressed.

FIG. 14 is a diagram showing another example of the IDT electrodes included in the first filter circuit 10. FIG. FIG. 14 also shows the IDT electrodes 61 forming the elastic wave resonators of the first filter circuit 10 .

In the example shown in FIG. 14, a piston mode is applied to the IDT electrode 61 by forming a wide portion 63 on each of the

electrode fingers

66a and 66b. The wide portions 63 are portions that serve as weights for the

electrode fingers

66a and 66b, and are provided at the tips and centers of the

electrode fingers

66a and 66b.

The wide portion 63 has a shape wider than the electrode finger 66a. The wide portion 63 shown in FIG. 14 has a rectangular shape, but is not limited thereto, and may have a T shape, a plus (+) shape, or a convex shape.

In the example shown in FIG. 14 as well, the piston mode is applied to at least some of the IDT electrodes 61 included in the first filter circuit 10, but the plurality of IDT electrodes 31 to 34 included in the additional circuit 20 are in the piston mode. is not applied. With this configuration, it is possible to prevent excessive energy from being trapped in the IDT electrodes 31 to 34 and reduce the power applied to the IDT electrodes 31 to 34 . As a result, shortening of the life of the elastic wave filter 1B can be suppressed.

FIG. 15 is a diagram showing another example of the IDT electrodes included in the first filter circuit 10. FIG. FIG. 15 also shows the IDT electrodes 61 that form the elastic wave resonators of the first filter circuit 10 .

In the example shown in FIG. 15, the

electrode fingers

66a and 66b are connected by the connecting bar 64, so that the IDT electrode 61 is applied in the piston mode.

The connecting bar 64 is an elongated rod-shaped electrode, for example, extends in the orthogonal direction d2 at the central portion of the electrode fingers 66a and connects the plurality of electrode fingers 66a. The width of the connecting bar 64 is equal to or less than the width of the electrode fingers 66a.

In the example shown in FIG. 15 as well, the piston mode is applied to at least some of the IDT electrodes 61 included in the first filter circuit 10. is not applied. With this configuration, it is possible to prevent excessive energy from being trapped in the IDT electrodes 31 to 34 and reduce the power applied to the IDT electrodes 31 to 34 . As a result, shortening of the life of the elastic wave filter 1B can be suppressed.

FIG. 16 is a diagram showing another example of the IDT electrodes included in the first filter circuit 10. FIG. FIG. 16 also shows the IDT electrodes 61 forming the elastic wave resonators of the first filter circuit 10 .

In the example shown in FIG. 16, each of the

electrode fingers

66a and 66b has a wide portion 63 and is connected by a connecting bar 64, so that the IDT electrode 61 is applied to the piston mode.

In the example shown in FIG. 16 as well, the piston mode is applied to at least some of the IDT electrodes 61 included in the first filter circuit 10, but the plurality of IDT electrodes 31 to 34 included in the additional circuit 20 are in the piston mode. is not applied. With this configuration, it is possible to prevent excessive energy from being trapped in the IDT electrodes 31 to 34 and reduce the power applied to the IDT electrodes 31 to 34 . As a result, shortening of the life of the elastic wave filter 1B can be suppressed.

FIG. 17 is a diagram showing the withstand power of the elastic wave filter 1B according to Modification 2 of Embodiment 1. FIG. FIG. 17(a) shows a schematic diagram of the elastic wave filter 1B. In (b) of FIG. 17 , the withstand power of the acoustic wave filter 1B of Modification 2 is indicated by circles, and the withstand power of the acoustic wave filter of the comparative example is indicated by triangles. Modification 2 is an example in which the piston mode is not applied to the additional circuit 20 , and Comparative Example is an example in which the piston mode is applied to the additional circuit 20 . As shown in (b) of FIG. 17 , Modified Example 2, in which the piston mode is not applied, has a higher power handling capability than the Comparative Example, in which the piston mode is applied.

[Modification 3 of Embodiment 1]
An elastic wave filter 1C according to Modification 3 of Embodiment 1 will be described with reference to FIGS. 18 and 19. FIG. In Modification 3, an example in which the distance (gap) g between the intersecting electrode fingers and the offset electrode fingers is larger in the additional circuit 20 than in the first filter circuit 10 will be described.

18 is a plan view showing the IDT electrode 61 included in the first filter circuit 10 of the elastic wave filter 1C according to Modification 3. FIG.

As shown in FIG. 18, the IDT electrode 61 of the first filter circuit 10 has a pair of a first comb-shaped electrode 61a and a second comb-shaped electrode 61b. The first comb-shaped electrode 61a has a busbar electrode 67a extending in the elastic wave propagation direction d1, and intersecting electrode fingers 68a and offset electrode fingers 69a connected to the busbar electrode 67a and extending in the orthogonal direction d2 (plus side). are doing. The second comb-shaped electrode 61b has a busbar electrode 67b extending in the acoustic wave propagation direction d1, intersecting electrode fingers 68b and offset electrode fingers 69b connected to the busbar electrode 67b and extending in the orthogonal direction d2 (minus side). are doing.

The intersecting

electrode fingers

68a and 68b cross each other when viewed from the elastic wave propagation direction d1. The offset electrode fingers 69a are shorter in length than the cross electrode fingers 68a, and the offset electrode fingers 69b are shorter in length than the cross electrode fingers 68b. The intersecting electrode fingers 68a of the first comb-shaped electrode 61a and the offset electrode fingers 69b of the second comb-shaped electrode 61b face each other in the orthogonal direction d2. The offset electrode fingers 69a of one comb-shaped electrode 61a face each other in the orthogonal direction d2.

19 is a plan view showing the IDT electrode 31 included in the additional circuit 20 of the elastic wave filter 1C according to Modification 3. FIG. Among the IDT electrodes 31 to 34, the IDT electrode 31 will be described below as an example.

As shown in FIG. 19, the IDT electrode 31 of the additional circuit 20 is composed of a first comb-shaped electrode 31a and a second comb-shaped electrode 31b. The first comb-shaped electrode 31a has a busbar electrode 37a extending in the elastic wave propagation direction d1, and intersecting electrode fingers 38a and offset electrode fingers 39a connected to the busbar electrode 37a and extending in the orthogonal direction d2 (plus side). are doing. The second comb-shaped electrode 31b has a busbar electrode 37b extending in the acoustic wave propagation direction d1, intersecting electrode fingers 38b and offset electrode fingers 39b connected to the busbar electrode 37b and extending in the orthogonal direction d2 (minus side). are doing.

The intersecting

electrode fingers

38a and 38b cross each other when viewed from the elastic wave propagation direction d1. The offset electrode fingers 39a are shorter in length than the cross electrode fingers 38a, and the offset electrode fingers 39b are shorter in length than the cross electrode fingers 38b. The intersecting electrode fingers 38a of the first comb-shaped electrode 31a and the offset electrode fingers 39b of the second comb-shaped electrode 31b face each other in the orthogonal direction d2, and the intersecting electrode fingers 38b of the second comb-shaped electrode 31b and the offset electrode fingers 39b of the second comb-shaped electrode 31b The offset electrode fingers 39a of one comb-shaped electrode 31a face each other in the orthogonal direction d2.

In Modified Example 3, the distance g between the intersecting electrode fingers 38a and the offset electrode fingers 39b, which face each other in the orthogonal direction d2 in the IDT electrodes 31 of the additional circuit 20, is the same as that in the IDT electrodes 61 of the first filter circuit 10 in the orthogonal direction d2. is wider than the interval g between the intersecting electrode fingers 68a and the offset electrode fingers 69b facing each other. Further, the distance g between the intersecting electrode fingers 38b and the offset electrode fingers 39a facing each other in the orthogonal direction d2 at the IDT electrodes 31 of the additional circuit 20 is is wider than the interval g between the intersecting electrode finger 68b and the offset electrode finger 69a. With this configuration, it is possible to prevent excessive energy from being trapped in the IDT electrodes 31 to 34 and reduce the power applied to the IDT electrodes 31 to 34 . As a result, shortening of the life of the acoustic wave filter 1C can be suppressed.

[Modification 4 of Embodiment 1]
An elastic wave filter 1D according to Modification 4 of Embodiment 1 will be described with reference to FIG. In Modified Example 4, an example in which the film thickness of the dielectric layer 326 formed on the IDT electrode is different will be described.

FIG. 20 is a cross-sectional view showing dielectric layers 326 formed in the first filter circuit 10 and the additional circuit 20 of the elastic wave filter 1D according to Modification 4. FIG.

The dielectric layer 326 is, for example, a film whose main component is silicon dioxide (SiO ₂ ). The dielectric layer 326 is provided for the purpose of adjusting the frequency-temperature characteristics of the acoustic wave resonator and the longitudinally coupled acoustic wave resonator 25, protecting the electrode layer 325 from the external environment, or improving moisture resistance. It is In FIG. 20, the dielectric layer 326 is formed so that the IDT electrodes formed on the series arm resonators S11 to S15 are thicker than the IDT electrodes formed on the parallel arm resonators P11 to P14. . The dielectric layer 326 has the same thickness for the series arm resonator having the highest antiresonance frequency among the series arm resonators S11 to S15 and the IDT electrodes 31 to 34 of the longitudinally coupled acoustic wave resonator 25. It is formed to be According to this configuration, in the ladder filter, the temperature characteristics of the series arm resonator having the highest anti-resonance frequency and the additional circuit 20 can be matched.

[Modification 5 of Embodiment 1]
An elastic wave filter 1 according to Modification 5 of Embodiment 1 will be described with reference to FIG.

FIG. 21 is a circuit configuration diagram of a multiplexer 5 including an elastic wave filter 1 according to Modification 5 of Embodiment 1. FIG.

In the acoustic wave filter 1 shown in FIG. 21, capacitive elements C1 and C3 are provided on the second path r2. Specifically, the IDT electrode 31 and the capacitive element C1 are arranged on the partial route r21, and the IDT electrode 33 and the capacitive element C3 are arranged on the partial route r23. The acoustic wave filter 1 of Modification 5 can also secure the attenuation amount in the attenuation band and reduce the power consumption.

(Embodiment 2)
Embodiment 2 will be described with reference to FIGS. 22 and 23. FIG. In the second embodiment, an example in which the passband of the elastic wave filter 1E is set to be higher than the passband of the second filter circuit 50 will be described.

FIG. 22 is a circuit configuration diagram of a multiplexer 5E including an acoustic wave filter 1E according to Embodiment 2. FIG.

The multiplexer 5E is a demultiplexer or multiplexer with multiple filters. The multiplexer 5E includes an elastic wave filter 1E having a first filter circuit 10 and an additional circuit 20, and a second filter circuit 50. FIG. Further, the multiplexer 5E is connected to a first terminal T1 connected to the elastic wave filter 1E, a second terminal T2 connected to both the elastic wave filter 1E and the second filter circuit 50, and a second filter circuit 50. and a third terminal T3. The basic configurations of the elastic wave filter 1E, the second filter circuit 50, the first terminal T1, the second terminal T2 and the third terminal T3 are the same as in the first embodiment.

High-frequency signals of, for example, Band 13 (transmission band: 777 MHz-787 MHz, reception band: 746 MHz-756 MHz) or Band 20 (transmission band: 832 MHz-862 MHz, reception band: 791 MHz-821 MHz) are input to and output from the multiplexer 5E. .

The elastic wave filter 1E of Embodiment 2 has the configuration shown below in order to secure the attenuation amount in the attenuation band and to reduce the power consumption.

FIG. 23 is a diagram showing the passband and attenuation band of the elastic wave filter 1E. The figure also shows the pass band of the second filter circuit 50 .

FIG. 23 shows the lowest frequency fL3 and the highest frequency fH3 of the passband of the first filter circuit 10. FIG. FIG. 23 also shows the predetermined frequency fL4 of the attenuation band located on the lower frequency side than the pass band of the first filter circuit 10. As shown in FIG. The predetermined frequency fL4 is, for example, the lowest frequency of the passband of the second filter circuit 50. FIG. A frequency fH4 within the attenuation band in the figure is, for example, the highest frequency of the passband of the second filter circuit 50 .

fy defined as

Further, among the plurality of IDT electrodes 31 to 34, the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 connected to the first path r1 on the side of the first terminal T1 when viewed from the longitudinally coupled acoustic wave resonator 25 is The frequency corresponding to the wavelength when the average is 1/2 wavelength (λ/2) is defined as fiy. Among the plurality of IDT electrodes 31 to 34, the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

32 and 34 connected to the first path r1 on the second terminal T2 side when viewed from the longitudinally coupled acoustic wave resonator 25 is The frequency corresponding to the wavelength when the average is 1/2 wavelength (λ/2) is defined as foy.

Under these definitions, the elastic wave filter 1E according to the present embodiment is
(3) fiy<0.945×fL3, and
(4) fL4<foy<0.965×fL3
It has a relationship of With this configuration, the attenuation in the attenuation band of the elastic wave filter 1E can be ensured, and the power consumption can be reduced.

For example, as shown by (3) fiy<0.945×fL3 and (4) foy<0.965×fL3, the frequency fiy and the frequency foy are not too close to the passband of the acoustic wave filter 1E. By setting it as low as possible, it is possible to prevent the power consumption from increasing more than necessary. Further, as indicated by fL4<foy in (4), the attenuation amount in the attenuation band can be ensured by setting the frequency foy higher than the predetermined frequency fL4 to be within the attenuation band. Note that the frequency fy calculated from the total average of the arrangement pitch p of the electrode fingers 36 of the IDT electrodes 31 to 34 should be 0.85×fL3≦fy so that the frequency fiy and the frequency foy are not too far apart. is desirable. Further, in the elastic wave filter 1E, power consumption can be reduced by setting the frequency fiy and the frequency foy to satisfy the relationship of fiy<foy.

(summary)
As described above, the elastic wave filter 1 according to the present embodiment includes the first terminal T1 and the second terminal T2, and the first terminal T1 and the second terminal T2 provided in the first route r1 connecting the first terminal T1 and the second terminal T2. 1 filter circuit 10 and an additional circuit 20 provided in a second route r2 connected in parallel with at least part of the first route r1. The additional circuit 20 has a longitudinally coupled acoustic wave resonator 25 . The longitudinally coupled acoustic wave resonator 25 has a plurality of IDT electrodes 31-34 arranged along the acoustic wave propagation direction d1. Among the plurality of IDT electrodes 31 to 34, the average arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 connected to the first path r1 on the first terminal T1 side when viewed from the longitudinally coupled acoustic wave resonator 25 is Let fix be the frequency corresponding to the wavelength when the wavelength is set to 1/2. Let fox be the frequency corresponding to the wavelength when the average of the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

32 and 34 is 1/2 wavelength, let fH1 be the highest frequency of the pass band of the first filter circuit 10, When fH2 is a predetermined frequency in the attenuation band located on the higher frequency side than the pass band of the first filter circuit 10, the acoustic wave filter 1
(1) having a relationship of 1.055×fH1<fix, and
(2) It has a relationship of 1.035×fH1<fox<fH2.

For example, as shown by 1.055×fH1<fix in (1) and 1.035×fH1<fox in (2), frequency fix and frequency fox are not too close to the passband of elastic wave filter 1. By setting the power consumption higher than necessary, it is possible to prevent the power consumption from increasing more than necessary. Further, as indicated by fox<fH2 in (2), the attenuation amount in the attenuation band can be ensured by making the frequency fox lower than the predetermined frequency fH2 and within the attenuation band. As a result, the attenuation in the attenuation band of the acoustic wave filter 1 can be ensured, and the power consumption can be reduced.

In addition, the elastic wave filter 1 may further have a relationship of fox<fix.

According to this configuration, for example, the frequency fix on the side of the

IDT electrodes

31 and 33 to which the high frequency signal is input can be increased. Thereby, the above frequency fix can be separated from the passband, and the power consumption of the elastic wave filter 1 can be further reduced.

Also, the predetermined frequency within the attenuation band may be the highest frequency of the passband of the second filter circuit 50 different from the first filter circuit 10 .

According to this configuration, attenuation in the passband of the second filter circuit 50 can be ensured. Thereby, it is possible to suppress the deterioration of the pass characteristic of the second filter circuit 50 .

Also, the first filter circuit 10 may be a transmission filter circuit in a predetermined band, and the second filter circuit 50 may be a reception filter circuit in a predetermined band.

According to this configuration, it is possible to ensure the amount of attenuation in the passband of the reception filter. Thereby, it is possible to suppress the deterioration of the pass characteristic of the reception filter.

Further, the additional circuit 20 has a plurality of

reflectors

41 and 42 positioned on both outer sides of the longitudinally coupled acoustic wave resonator 25 in the acoustic wave propagation direction d1. The number may be 10 or less.

According to this configuration, it is possible to reduce the multiple reflections of the

reflectors

41 and 42 and weaken the excitation of the IDT electrodes 31-34. Thereby, the power consumption of the elastic wave filter 1A can be reduced.

Further, the additional circuit 20 may further include a capacitive element (at least one of capacitive elements C1, C2, C3 and C4) provided on the second path r2.

According to this configuration, the instantaneous power entering the IDT electrodes 31-34 can be reduced. Thereby, shortening of the life of the elastic wave filter 1 can be suppressed.

The acoustic wave filter 1B according to the present embodiment includes a first terminal T1 and a second terminal T2, a first filter circuit 10 provided on a first route r1 connecting the first terminal T1 and the second terminal T2, and an additional circuit 20 provided in a second route r2 connected in parallel with at least part of the first route r1. The additional circuit 20 has a longitudinally coupled acoustic wave resonator 25 . The longitudinally coupled acoustic wave resonator 25 has a plurality of IDT electrodes 31-34 arranged along the acoustic wave propagation direction d1. The first filter circuit 10 includes a plurality of IDT electrodes 61 different from the plurality of IDT electrodes 31 to 34 of the longitudinally coupled acoustic wave resonator 25, and the other plurality of IDT electrodes 61 included in the first filter circuit 10. , the piston mode is applied to the plurality of IDT electrodes 31 to 34 included in the additional circuit 20, and the piston mode is not applied.

According to this configuration, the excitation energy in the IDT electrodes 31-34 included in the additional circuit 20 can be reduced. As a result, shortening of the life of the elastic wave filter 1B can be suppressed.

The elastic wave filter 1C according to the present embodiment includes a first terminal T1 and a second terminal T2, a first filter circuit 10 provided on a first route r1 connecting the first terminal T1 and the second terminal T2, and an additional circuit 20 provided in a second route r2 connected in parallel with at least part of the first route r1. The additional circuit 20 has a longitudinally coupled acoustic wave resonator 25 . The longitudinally coupled acoustic wave resonator 25 has a plurality of IDT electrodes 31-34 arranged along the acoustic wave propagation direction d1. The first filter circuit 10 includes a plurality of IDT electrodes 61 different from the plurality of IDT electrodes 31 to 34 of the longitudinally coupled acoustic wave resonator 25, and the other plurality of IDT electrodes 61 included in the first filter circuit 10. , and the plurality of IDT electrodes 31-34 included in the additional circuit 20 each have a pair of first comb-shaped

electrodes

61a, 31a-34a and second comb-shaped

electrodes

61b, 31b-34b. . Each of the first comb-shaped

electrodes

61a, 31a to 34a and the second comb-shaped

electrodes

61b, 31b to 34b includes a busbar electrode extending in the elastic wave propagation direction d1 and a busbar electrode connected to the busbar electrode to extend in the elastic wave propagation direction d1. It has a plurality of intersecting electrode fingers and a plurality of offset electrode fingers extending in an orthogonal direction d2. The intersecting electrode fingers of the first comb-shaped electrode and the offset electrode fingers of the second comb-shaped electrode face each other in the orthogonal direction d2, and the intersecting electrode fingers of the second comb-shaped electrode and the offset electrode fingers of the first comb-shaped electrode face each other. The offset electrode fingers are opposed to each other in the orthogonal direction d2. The distance g between the intersecting electrode fingers 38a (or 38b) and the offset electrode fingers 39b (or 39b) facing each other in the orthogonal direction d2 in the additional circuit 20 is the same as the intersecting electrode fingers 38a (or 38b) facing each other in the orthogonal direction d2 in the first filter circuit 10. It is wider than the interval g between the electrode finger 68a (or 68b) and the offset electrode finger 69b (or 69a).

According to this configuration, the excitation energy in the IDT electrodes 31-34 included in the additional circuit 20 can be reduced. As a result, shortening of the life of the acoustic wave filter 1C can be suppressed.

Among the plurality of IDT electrodes 31 to 34, the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 connected to the first path r1 on the side of the first terminal T1 when viewed from the longitudinally coupled acoustic wave resonator 25 is Let fix be the frequency corresponding to the wavelength when the average is 1/2 wavelength. Let fox be the frequency corresponding to the wavelength when the average of the arrangement pitch p of the electrode fingers 36 of the

connected IDT electrodes

32 and 34 is 1/2 wavelength, and fH1 be the highest frequency of the passband of the first filter circuit 10. and fH2 is a predetermined frequency in the attenuation band located on the higher frequency side than the passband of the first filter circuit 10, the elastic wave filter 1B or 1C is:
(1) having a relationship of 1.055×fH1<fix, and
(2) The relationship may be 1.035×fH1<fox<fH2.

For example, as shown by 1.055×fH1<fix in (1) and 1.035×fH1<fox in (2), frequency fix and frequency fox are set near the passband of elastic wave filter 1B or 1C. It is possible to prevent the power consumption from increasing more than necessary by setting the power consumption higher than necessary. Further, as indicated by fox<fH2 in (2), the attenuation amount in the attenuation band can be ensured by making the frequency fox lower than the predetermined frequency fH2 and within the attenuation band. As a result, the attenuation in the attenuation band of the acoustic wave filter 1B or 1C can be ensured, and the power consumption can be reduced.

In addition, the elastic wave filter 1B or 1C may further have a relationship of fox<fix.

IDT electrodes

31 and 33 to which the high frequency signal is input can be increased. As a result, the frequency fix can be separated from the passband, and the power consumption of the elastic wave filter 1B or 1C can be further reduced.

Further, the additional circuit 20 has a plurality of

reflectors

41 and 42 and weaken the excitation of the IDT electrodes 31-34. Thereby, the power consumption of the elastic wave filter 1B or 1C can be reduced.

IDT electrodes

31 and 33 connected to the first path r1 on the side of the first terminal T1 when viewed from the longitudinally coupled acoustic wave resonator 25 is Let fiy be the frequency corresponding to the wavelength when the average is 1/2 wavelength. Let foy be the frequency corresponding to the wavelength when the average of the arrangement pitch p of the electrode fingers 36 of the

connected IDT electrodes

32 and 34 is 1/2 wavelength, and fL3 be the lowest frequency of the passband of the first filter circuit 10. and fL4 is a predetermined frequency in the attenuation band located on the lower frequency side than the passband of the first filter circuit 10, the acoustic wave filter 1B or 1C is:
(3) having a relationship of fiy<0.945×fL3, and
(4) It has a relationship of fL4<foy<0.965×fL3.

For example, as shown by (3) fiy<0.945×fL3 and (4) foy<0.965×fL3, frequency fiy and frequency foy are set near the passband of elastic wave filter 1B or 1C. By setting the power consumption low, it is possible to prevent the power consumption from increasing more than necessary. Further, as indicated by fL4<foy in (4), the attenuation amount in the attenuation band can be ensured by setting the frequency foy higher than the predetermined frequency fL4 to be within the attenuation band. As a result, the attenuation in the attenuation band of the acoustic wave filter 1B or 1C can be ensured, and the power consumption can be reduced.

The acoustic wave filter 1E according to the present embodiment includes a first terminal T1 and a second terminal T2, a first filter circuit 10 provided on a first route r1 connecting the first terminal T1 and the second terminal T2, and an additional circuit 20 provided in a second route r2 connected in parallel with at least part of the first route r1. The additional circuit 20 has a longitudinally coupled acoustic wave resonator 25 . The longitudinally coupled acoustic wave resonator 25 has a plurality of IDT electrodes 31-34 arranged along the acoustic wave propagation direction d1. Among the plurality of IDT electrodes 31 to 34, the average arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

31 and 33 connected to the first path r1 on the first terminal T1 side when viewed from the longitudinally coupled acoustic wave resonator 25 is Let fiy be the frequency corresponding to the wavelength when the wavelength is set to 1/2. Let foy be the frequency corresponding to the wavelength when the average of the arrangement pitch p of the electrode fingers 36 of the

IDT electrodes

32 and 34 is 1/2 wavelength, fL3 be the lowest frequency of the passband of the first filter circuit 10, When a predetermined frequency in the attenuation band located on the lower frequency side than the passband of the first filter circuit 10 is fL4, the elastic wave filter 1E is
(3) having a relationship of fiy<0.945×fL3, and
(4) It has a relationship of fL4<foy<0.965×fL3.

For example, as shown by (3) fiy<0.945×fL3 and (4) foy<0.965×fL3, the frequency fiy and the frequency foy are not too close to the passband of the acoustic wave filter 1E. By setting it as low as possible, it is possible to prevent the power consumption from increasing more than necessary. Further, as indicated by fL4<foy in (4), the attenuation amount in the attenuation band can be ensured by setting the frequency foy higher than the predetermined frequency fL4 to be within the attenuation band. As a result, the attenuation in the attenuation band of the elastic wave filter 1E can be ensured, and the power consumption can be reduced.

Also, the predetermined frequency within the attenuation band may be the lowest frequency of the passband of the second filter circuit 50 different from the first filter circuit 10 .

A multiplexer 5 according to the present embodiment includes the elastic wave filter 1 described above and another filter having a second filter circuit 50 .

According to this, it is possible to provide the multiplexer 5 in which the attenuation in the passband of the second filter circuit 50 is ensured and the power consumption of the acoustic wave filter 1 is suppressed.

A multiplexer 5E according to the present embodiment includes the above elastic wave filter 1E and another filter having a second filter circuit 50.

According to this, it is possible to provide the multiplexer 5E in which the attenuation in the passband of the second filter circuit 50 is ensured and the power consumption of the elastic wave filter 1E is suppressed.

(Other embodiments)
As described above, the elastic wave filter and the like according to the embodiments of the present invention have been described with reference to the embodiments. , modifications obtained by applying various modifications to the above embodiments that can be considered by those skilled in the art without departing from the scope of the present invention, high-frequency front-end circuits and communication including elastic wave filters or multiplexers according to the present invention A device is also included in the present invention.

Although an example in which the longitudinally coupled acoustic wave resonator 25 has four IDT electrodes is shown above, the number of IDT electrodes may be two or more.

Although an example in which the elastic wave filter 1 is a transmission filter has been described above, the elastic wave filter 1 is not limited to this and may be a reception filter. Moreover, the multiplexer 5 is not limited to a configuration including both a transmission filter and a reception filter, and may be configured to include a plurality of transmission filters or a plurality of reception filters.

In the above description, a multiplexer including two filters has been described as an example. can also be applied. That is, the multiplexer only needs to have two or more filters.

Also, the second filter circuit 50 is not limited to the configuration of the filter described above, and can be appropriately designed according to the required filter characteristics and the like. Specifically, the second filter circuit 50 may have a longitudinal coupling filter structure or a ladder filter structure. Further, each resonator constituting the second filter circuit 50 is not limited to a SAW resonator, and may be, for example, a BAW (Bulk Acoustic Wave) resonator. Furthermore, the second filter circuit 50 may be configured without using resonators, and may be, for example, an LC resonance filter or a dielectric filter.

In addition, the materials constituting the IDT electrodes 31 to 34 and the electrode layers 325 and dielectric layers 326 of the

reflectors

41 and 42 are not limited to the materials described above. Also, the IDT electrodes 31 to 34 may not have the laminated structure described above. The IDT electrodes 31 to 34 may be composed of metals or alloys such as Ti, Al, Cu, Pt, Au, Ag, Pd, etc., or may be composed of a plurality of laminates composed of the above metals or alloys. may be configured.

Further, in Embodiment 1, a substrate having piezoelectricity is shown as the piezoelectric substrate 320, but the piezoelectric substrate may be a piezoelectric substrate composed of a single piezoelectric layer. The piezoelectric substrate in this case consists of, for example, a piezoelectric single crystal of LiTaO ₃ or another piezoelectric single crystal such as LiNbO ₃ . In addition, the piezoelectric substrate 320 on which the IDT electrodes 31 to 34 are formed may be entirely composed of a piezoelectric layer as long as it has piezoelectricity, or may have a structure in which a piezoelectric layer is laminated on a support substrate. good. Moreover, the cut angle of the piezoelectric substrate 320 according to the above embodiment is not limited. In other words, depending on the required transmission characteristics of the acoustic wave filter, the laminated structure, material, and thickness may be changed as appropriate, and the _LiTaO3 piezoelectric substrate or A surface acoustic wave filter using a LiNbO ₃ piezoelectric substrate or the like can also achieve the same effect.

The present invention can be widely used in communication devices such as mobile phones as multiplexers, front-end circuits, and communication devices having acoustic wave filters.

1, 1A, 1B, 1C, 1D, 1E elastic wave filter 5, 5E multiplexer 10 first filter circuit 20 additional circuit 25 longitudinally coupled elastic wave resonator 31, 32, 33, 34 IDT electrode 31a, 32a, 33a, 34a 1 comb-shaped electrode 31b, 32b, 33b, 34b 2nd comb-shaped electrode 36, 36a, 36b electrode finger 37a, 37b busbar electrode 38a, 38b intersecting electrode finger 39a, 39b offset electrode finger 41, 42 reflector 50 second second Filter circuit 61 IDT electrode 61a First comb-shaped electrode 61b Second comb-shaped electrode 62 Load film 63 Wide portion 64 Connection bar 66a, 66b Electrode fingers 67a, 67b Bus bar electrodes 68a, 68b Intersecting electrode fingers 69a, 69b Offset electrode fingers 320 Piezoelectric substrate 325 Electrode layer 326 Dielectric layer 330 Package substrate C1, C2, C3, C4, C10 Capacitive element d1 Elastic wave propagation direction d2 Orthogonal direction fix, fox, fiy, foy Frequency fL1, fL2, fL3, fL4 Passband lowest frequency fH1, fH2, fH3, fH4 highest frequency of passband g interval L11, L12 inductor n0, n1, n2, n3, n4, n5 node P11, P12, P13, P14, P21, P22 parallel arm resonator p array pitch Q21 elastic wave resonator R13 resistive element r1 first path r2 second path r21, r22, r23, r24 partial path r3 third path S11, S12, S13, S14, S15, S21 series arm resonator T1 first Terminal T2 Second terminal T3 Third terminal

Claims

a first terminal and a second terminal;
a first filter circuit provided on a first path connecting the first terminal and the second terminal;
an additional circuit provided in a second path connected in parallel with at least part of the first path;
with
The additional circuit has a longitudinally coupled acoustic wave resonator,
The longitudinally coupled acoustic wave resonator has a plurality of IDT electrodes arranged along the acoustic wave propagation direction,
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the first terminal side as viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is 1/2 wavelength Let fix be the frequency corresponding to the wavelength of
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side when viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is 1/2 wavelength Let fox be the frequency corresponding to the wavelength of
fH1 is the highest frequency of the passband of the first filter circuit,
When fH2 is a predetermined frequency within an attenuation band located on the higher frequency side than the pass band of the first filter circuit,
have a relationship of 1.055×fH1<fix, and
An elastic wave filter having a relationship of 1.035×fH1<fox<fH2.
The elastic wave filter according to claim 1, further having a relationship of fox<fix.
The acoustic wave filter according to claim 1 or 2, wherein the predetermined frequency within the attenuation band is the highest frequency of a passband of a second filter circuit different from the first filter circuit.
The first filter circuit is a circuit of a transmission filter in a predetermined band,
The elastic wave filter according to claim 3, wherein the second filter circuit is a reception filter circuit for the predetermined band.
The additional circuit has a plurality of reflectors positioned on both outer sides of the longitudinally coupled acoustic wave resonator in the acoustic wave propagation direction,
The elastic wave filter according to any one of claims 1 to 4, wherein the number of electrode fingers of each of the plurality of reflectors is 10 or less.
The elastic wave filter according to any one of claims 1 to 5, wherein the additional circuit further includes a capacitive element provided on the second path.
a first terminal and a second terminal;
a first filter circuit provided on a first path connecting the first terminal and the second terminal;
an additional circuit provided in a second path connected in parallel with at least part of the first path;
with
The additional circuit has a longitudinally coupled acoustic wave resonator,
The longitudinally coupled acoustic wave resonator has a plurality of IDT electrodes arranged along the acoustic wave propagation direction,
The first filter circuit is composed of a plurality of IDT electrodes different from the plurality of IDT electrodes of the longitudinally coupled acoustic wave resonator,
A piston mode is applied to at least some of the other plurality of IDT electrodes included in the first filter circuit,
A piston mode is not applied to the plurality of IDT electrodes included in the additional circuit. An acoustic wave filter.
a first terminal and a second terminal;
a first filter circuit provided on a first path connecting the first terminal and the second terminal;
an additional circuit provided in a second path connected in parallel with at least part of the first path;
with
The additional circuit has a longitudinally coupled acoustic wave resonator,
The longitudinally coupled acoustic wave resonator has a plurality of IDT electrodes arranged along the acoustic wave propagation direction,
The first filter circuit is composed of a plurality of IDT electrodes different from the plurality of IDT electrodes of the longitudinally coupled acoustic wave resonator,
Each of the other plurality of IDT electrodes included in the first filter circuit and the plurality of IDT electrodes included in the additional circuit has a pair of a first comb-shaped electrode and a second comb-shaped electrode. death,
Each of the first comb-shaped electrode and the second comb-shaped electrode includes a bus bar electrode extending in the elastic wave propagation direction and a plurality of bus bar electrodes connected to the bus bar electrode and extending in a direction orthogonal to the elastic wave propagation direction. a cross electrode finger and a plurality of offset electrode fingers;
the intersecting electrode fingers of the first comb-shaped electrode and the offset electrode fingers of the second comb-shaped electrode face each other in the orthogonal direction;
the intersecting electrode fingers of the second comb-shaped electrode and the offset electrode fingers of the first comb-shaped electrode face each other in the orthogonal direction;
The distance between the intersecting electrode fingers and the offset electrode fingers facing each other in the orthogonal direction in the additional circuit is the same as the intersecting electrode fingers and the offset electrode fingers facing in the orthogonal direction in the first filter circuit. Acoustic wave filter wider than the spacing of .
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the first terminal side as viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is set to 1/2 wavelength Let fix be the frequency corresponding to the wavelength of
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side when viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is 1/2 wavelength Let fox be the frequency corresponding to the wavelength of
fH1 is the highest frequency of the passband of the first filter circuit,
When fH2 is a predetermined frequency within the attenuation band located on the higher frequency side than the pass band of the first filter circuit,
have a relationship of 1.055×fH1<fix, and
The acoustic wave filter according to claim 7 or 8, having a relationship of 1.035 x fH1<fox<fH2.
The elastic wave filter according to claim 9, further having a relationship of fox<fix.
The elastic wave filter according to claim 9 or 10, wherein the predetermined frequency within the attenuation band is the highest frequency of a passband of a second filter circuit different from the first filter circuit.
The first filter circuit is a circuit of a transmission filter in a predetermined band,
The elastic wave filter according to claim 11, wherein the second filter circuit is a reception filter circuit for the predetermined band.
The additional circuit has a plurality of reflectors positioned on both outer sides of the longitudinally coupled acoustic wave resonator in the acoustic wave propagation direction,
The elastic wave filter according to any one of claims 7 to 12, wherein the number of electrode fingers of each of the plurality of reflectors is 10 or less.
The elastic wave filter according to any one of claims 7 to 13, wherein the additional circuit further includes a capacitive element provided on the second path.
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the first terminal side as viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is set to 1/2 wavelength Let fiy be the frequency corresponding to the wavelength of
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side when viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is 1/2 wavelength Let foy be the frequency corresponding to the wavelength of
fL3 is the lowest frequency of the passband of the first filter circuit,
When fL4 is a predetermined frequency within the attenuation band located on the lower frequency side than the pass band of the first filter circuit,
having a relationship of fiy<0.945×fL3, and
The elastic wave filter according to claim 7 or 8, having a relationship of fL4<foy<0.965×fL3.
a first terminal and a second terminal;
a first filter circuit provided on a first path connecting the first terminal and the second terminal;
an additional circuit provided in a second path connected in parallel with at least part of the first path;
with
The additional circuit has a longitudinally coupled acoustic wave resonator,
The longitudinally coupled acoustic wave resonator has a plurality of IDT electrodes arranged along the acoustic wave propagation direction,
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the first terminal side as viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is set to 1/2 wavelength Let fiy be the frequency corresponding to the wavelength of
When the average of the arrangement pitch of the electrode fingers of the IDT electrodes connected to the first path on the second terminal side when viewed from the longitudinally coupled acoustic wave resonator among the plurality of IDT electrodes is 1/2 wavelength Let foy be the frequency corresponding to the wavelength of
fL3 is the lowest frequency of the passband of the first filter circuit,
When fL4 is a predetermined frequency within the attenuation band located on the lower frequency side than the pass band of the first filter circuit,
having a relationship of fiy<0.945×fL3, and
An elastic wave filter having a relationship of fL4<foy<0.965×fL3.
The elastic wave filter according to claim 16, wherein the predetermined frequency within the attenuation band is the lowest frequency in the passband of a second filter circuit different from the first filter circuit.
The first filter circuit is a circuit of a transmission filter in a predetermined band,
The elastic wave filter according to claim 17, wherein the second filter circuit is a receive filter circuit for the predetermined band.
An elastic wave filter according to claim 3 or 4;
another filter having the second filter circuit;
A multiplexer with
An elastic wave filter according to claim 17 or 18;
another filter having the second filter circuit;
A multiplexer with