Filter device and multiplexer

Abstract

To provide a filter device capable of suppressing an influence of an unwanted wave in the case where it is used for a multiplexer.SOLUTION: In a multiplexer 1, a first filter 1A comprises: first and second signal terminals 3A and 3B; and a plurality of serial and parallel arm resonators. At least one of them is an excitation angle change type resonator, and an electrode finger of a plurality of IDT electrodes is bent. When a pair of adjacent serial and parallel arm resonators is one ladder part, half the ladder parts positioned at a first signal terminal side among all of the ladder parts are a first half ladder part, and when the resonator positioned at the most first signal terminal side to the serial and parallel arm resonator in the ladder part positioned at the most second signal terminal side in the first half ladder part among the plurality of resonators are first half resonators (serial arm resonators S1a to S1c, S2a, S2b, and S3a, and parallel arm resonators of parallel arm resonator parts P1 and P2), at least one of the first half resonators is the excitation angle change type resonator.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a filter device and a multiplexer having a plurality of acoustic wave resonators.

[0002] Conventionally, filters including a plurality of acoustic wave resonators have been widely used in mobile phones and the like. Patent Document 1 below discloses an example of a quadplexer as a multiplexer. This quadplexer has a transmission filter and a reception filter for Band 1, and a transmission filter and a reception filter for Band 3. Each filter is commonly connected to a common terminal. The common terminal is a terminal on the antenna side. Each filter includes a plurality of resonators. Each of these resonators has an IDT (Interdigital Transducer) electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 003296 Summary of the Invention [Problem to be solved by the invention]

[0004] When filters for multiple communication bands are commonly connected to a terminal connected to an antenna, unwanted waves generated in a resonator close to the terminal often affect the filter characteristics of the other filters. For example, when a Rayleigh wave occurs in a resonator of a Band 1 receiving filter, the frequency of the Rayleigh wave is located in the passband of a Band 3 transmitting filter. Therefore, in the Band 3 transmitting filter of the quadplexer described in Patent Document 1, the insertion loss tends to be large due to the Rayleigh wave generated in the resonator of the Band 1 receiving filter.

[0005] An object of the present invention is to provide a filter device capable of suppressing the influence of spurious waves when used in a multiplexer, and a multiplexer capable of suppressing the influence of spurious waves. [Means for solving the problem]

[0006] A filter device according to the present invention includes a first signal terminal and a second signal terminal, and a plurality of resonators including a plurality of series arm resonators and a plurality of parallel arm resonators, at least one of the plurality of series arm resonators and the plurality of parallel arm resonators is an excitation angle variable resonator, the excitation angle variable resonator has a piezoelectric substrate including a piezoelectric layer and an IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, the piezoelectric layer has a propagation axis, the plurality of electrode fingers are curved, an excitation direction of an acoustic wave in an arbitrary portion of an arbitrary electrode finger among the plurality of electrode fingers is any one of first to third directions, the first direction is a direction perpendicular to a direction in which the electrode finger extends, the second direction is a direction connecting the electrode finger and the electrode finger adjacent to the electrode finger by a shortest distance, the third direction is a direction of an electric field vector generated between the electrode finger and the electrode finger adjacent to the electrode finger, and when the excitation angle is an angle formed by an angle between the direction in which the parallel arm resonator extends and the IDT electrode of the variable excitation angle resonator, and when a pair of adjacent series arm resonators and parallel arm resonators are defined as one ladder section, a plurality of ladder sections are configured between the first signal terminal and the second signal terminal, and at least one of the series arm resonators and the parallel arm resonators in each of the adjacent ladder sections are different resonators from each other, when the half of all the ladder sections that is located on the first signal terminal side is defined as a first half ladder section, and when the first half resonators are defined as a series arm resonator of the plurality of resonators to the series arm resonator and the parallel arm resonator of the ladder section that is located on the second signal terminal side in the first half ladder section, at least one of the first half resonators is the variable excitation angle resonator.

[0007] The multiplexer of the present invention is a filter device comprising a common connection terminal and a plurality of filters including a first filter and a second filter commonly connected to the common connection terminal, wherein at least the first filter of the plurality of filters is configured according to the present invention. Effect of the Invention

[0008] According to the present invention, it is possible to provide a filter device capable of suppressing the influence of unwanted waves when used in a multiplexer, and a multiplexer capable of suppressing the influence of unwanted waves. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic circuit diagram of a multiplexer according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a circuit diagram for explaining a ladder section of a first filter in the first embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic plan view of a first filter in the first embodiment of the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line II in FIG. [Diagram 5] 1 is a schematic plan view of an excitation angle variable resonator of a first filter according to a first embodiment of the present invention. FIG. [Figure 6] FIG. 2 is a schematic plan view of a first filter in the first embodiment of the present invention. [Figure 7] 2 is a schematic plan view of an elastic wave resonator other than an excitation angle variable resonator of a first filter in a first preferred embodiment of the present invention. FIG. [Figure 8] FIG. 2 is a diagram showing attenuation frequency characteristics of a first filter, a second filter, a third filter, and a fourth filter in the first embodiment of the present invention. [Figure 9] FIG. 4 is a diagram showing the attenuation frequency characteristics of a second filter in the first embodiment of the present invention and the first comparative example. [Figure 10]10 is a diagram showing phase characteristics of an excitation angle changing resonator and an elastic wave resonator having an inclined IDT electrode. FIG. [Figure 11] FIG. 3 is a diagram showing return losses in the first embodiment of the present invention, the first to fourth modified examples thereof, and a first comparative example. [Figure 12] 3 is a schematic plan view showing a circle including an arc when a shape of an electrode finger in a plan view of an IDT electrode according to the first embodiment of the present invention is approximated to the arc. FIG. [Figure 13] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter according to a fifth modified example of the first embodiment of the present invention. [Figure 14] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter in a sixth modified example of the first embodiment of the present invention. [Figure 15] FIG. 13 is a schematic plan view showing parallel regions and non-parallel regions in a sixth modified example of the first embodiment of the present invention. [Figure 16] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter according to a seventh modified example of the first embodiment of the present invention. [Figure 17] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter according to an eighth modified example of the first embodiment of the present invention. [Figure 18] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter according to a ninth modified example of the first embodiment of the present invention. [Figure 19] FIG. 23 is a schematic plan view showing the vicinity of a first edge region and a second edge region in an excitation angle variable resonator of a first filter in a tenth modified example of the first embodiment of the present invention. [Figure 20]11(a) is a schematic cross-sectional view showing a cross section along the extension direction of a first electrode finger in a first edge region, a second edge region, and a central region of the first electrode finger in an eleventh modified example of the first embodiment of the present invention, and 11(b) is a schematic cross-sectional view showing a cross section along the extension direction of a second electrode finger in a first edge region, a second edge region, and a central region of the second electrode finger in an eleventh modified example of the first embodiment of the present invention. [Figure 21] FIG. 23 is a schematic plan view of an excitation angle variable resonator of the first filter in a twelfth modified example of the first embodiment of the present invention. [Figure 22] FIG. 5 is a schematic circuit diagram of a multiplexer according to a second embodiment of the present invention. [Figure 23] FIG. 11 is a schematic plan view of a first filter in a second embodiment of the present invention. [Figure 24] FIG. 11 is a diagram showing the attenuation-frequency characteristics of the first filter in the second embodiment of the present invention and the first comparative example, near a frequency at which a Rayleigh wave is generated. [Diagram 25] FIG. 4 is a diagram showing attenuation frequency characteristics in the vicinity of a frequency at which a Rayleigh wave is generated, of a first filter in the first embodiment of the present invention and a first comparative example. [Figure 26] FIG. 4 is a diagram showing return losses in the first and second embodiments of the present invention and a first comparative example. [Figure 27] FIG. 11 is a schematic circuit diagram of a multiplexer according to a third embodiment of the present invention. [Figure 28] FIG. 13 is a schematic circuit diagram of a multiplexer according to a modified example of the third embodiment of the present invention. [Figure 29] FIG. 13 is a diagram illustrating return losses in the third embodiment of the present invention, its modified example, and a second comparative example. [Diagram 30] FIG. 13 is a schematic circuit diagram of a multiplexer according to a fourth embodiment of the present invention. [Diagram 31] FIG. 13 is a schematic circuit diagram of a multiplexer according to a fifth embodiment of the present invention. [Diagram 32]FIG. 13 is a circuit diagram for explaining a ladder section of a first filter in a fifth embodiment of the present invention. [Diagram 33] FIG. 13 is a schematic plan view of a plurality of excitation angle variable resonators of a first filter according to a sixth embodiment of the present invention. [Diagram 34] FIG. 13 is a diagram showing the phase characteristics of each excitation angle variable resonator in the sixth embodiment of the present invention. [Diagram 35] FIG. 11 is a diagram showing return losses in the first embodiment of the present invention, the sixth embodiment, and the first comparative example. [Diagram 36] FIG. 13 is a circuit diagram of a multiplexer according to a seventh embodiment of the present invention. [Figure 37] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter according to an eighth embodiment of the present invention. [Figure 38] FIG. 23 is a schematic front sectional view of an excitation angle variable resonator of a first filter in a first modified example of the eighth embodiment of the present invention. [Figure 39] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter in a second modified example of the eighth embodiment of the present invention. [Diagram 40] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter according to a ninth embodiment of the present invention. [Diagram 41] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter according to a tenth embodiment of the present invention. [Diagram 42] FIG. 26 is a schematic front sectional view of an excitation angle variable resonator of a first filter in a first modified example of the tenth embodiment of the present invention. [Diagram 43] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter in a second modified example of the tenth embodiment of the present invention. [Diagram 44] FIG. 23 is a schematic cross-sectional front view of an excitation angle variable resonator of a first filter in a third modified example of the tenth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be clarified below by describing specific embodiments of the present invention with reference to the drawings.

[0011] It should be noted that each embodiment described in this specification is merely illustrative, and partial substitution or combination of configurations is possible between different embodiments.

[0012] Fig. 1 is a schematic circuit diagram of a multiplexer according to a first embodiment of the present invention, in which second to fourth filters, which will be described later, are shown in block diagram form.

[0013] 1, the multiplexer 1 of this embodiment is a quadplexer. The multiplexer 1 includes a first filter 1A, a second filter 1B, a third filter 1C, and a fourth filter 1D. The first filter 1A is a filter device according to one embodiment of the present invention.

[0014] The multiplexer 1 is not limited to a quadplexer. The multiplexer 1 may have at least a first filter 1A and a second filter 1B. The multiplexer 1 may be a multiplexer having two or more filters, such as a duplexer, a triplexer, or a quintplexer.

[0015] Each filter of the multiplexer 1 is a band-pass filter. Therefore, each filter has its own pass band. More specifically, the communication bands of the multiplexer 1 are Band1 and Band3.

[0016] The first filter 1A is a receive filter for Band 1. The pass band of the first filter 1A is 2110 MHz to 2170 MHz. The second filter 1B is a transmit filter for Band 3. The pass band of the second filter 1B is 1710 MHz to 1785 MHz. The third filter 1C is a receive filter for Band 3. The pass band of the third filter 1C is 1805 MHz to 1880 MHz. The fourth filter 1D is a transmit filter for Band 1. The pass band of the fourth filter 1D is 1920 MHz to 1980 MHz. However, the communication bands of the multiplexer 1 are not limited to the above.

[0017] The multiplexer 1 has a common connection terminal 7. A first filter 1A, a second filter 1B, a third filter 1C, and a fourth filter 1D are commonly connected to the common connection terminal 7. In this embodiment, the common connection terminal 7 is an antenna terminal. The antenna terminal is connected to an antenna. The common connection terminal 7 may be configured as, for example, a wiring line or an electrode pad.

[0018] An inductor L is connected between the common connection terminal 7 and the ground potential. The inductor L is an inductor for adjusting impedance. Note that the inductor L is not necessarily provided.

[0019] The first filter 1A has a first signal terminal 3A and a second signal terminal 3B, a plurality of ground terminals, and a plurality of resonators. The first signal terminal 3A is an input terminal of the first filter 1A. The second signal terminal 3B is an output terminal of the first filter 1A. The ground terminal is a terminal connected to a ground potential. The plurality of resonators are a plurality of series arm resonators and a plurality of parallel arm resonators. The first filter 1A is a ladder type filter.

[0020] Of the first signal terminal 3A and the second signal terminal 3B, the first signal terminal 3A is located on the common connection terminal 7 side. The first signal terminal 3A is electrically connected to the common connection terminal 7 by wiring or the like. Therefore, in the first filter 1A, the first signal terminal 3A is an antenna terminal.

[0021] In this embodiment, all of the series arm resonators and all of the parallel arm resonators in the first filter 1A are acoustic wave resonators. All of the acoustic wave resonators in the first filter 1A have an IDT electrode.

[0022] In addition, the circuit configuration of the first filter 1A includes a series arm S, multiple parallel arms P, and multiple nodes D. The series arm S is a path connecting a first signal terminal 3A serving as an input terminal and a second signal terminal 3B serving as an output terminal. Each series arm resonator is provided in the series arm S. Meanwhile, each parallel arm P is a path branching from the series arm S to each ground terminal. Each parallel arm P is provided with a parallel arm resonator. Meanwhile, the node D is a connection point between the series arm S and the parallel arm P.

[0023] The first filter 1A has a plurality of series arm resonator sections. The series arm resonator section is one series arm resonator or a group of a plurality of series arm resonators connected in series or in parallel to each other without a node D. More specifically, the series arm resonator section is a portion in which one or more series arm resonators are provided between an input terminal and a node D, between the nodes D, or between the node D and an output terminal. As described above, in the first filter 1A, the input terminal is the first signal terminal 3A, and the output terminal is the second signal terminal 3B. The series arm resonator section may be, for example, a portion made up of a plurality of split-type series arm resonators.

[0024] The multiple series arm resonator sections of the first filter 1A are specifically the series arm resonator section S1, the series arm resonator section S2, the series arm resonator section S3, the series arm resonator section S4, and the series arm resonator section S5. In this embodiment, the series arm resonator section S1 is made up of multiple series-divided series arm resonators. That is, in the series arm resonator section S1, multiple divided series arm resonators are connected in series to each other. Similarly, the series arm resonator section S2 and the series arm resonator section S3 are made up of multiple series-divided series arm resonators. On the other hand, each of the series arm resonator sections S4 and S5 is made up of one series arm resonator.

[0025] In addition, when the series arm resonator section includes a plurality of series arm resonators, the plurality of series arm resonators do not need to be series-divided series arm resonators. The relationship between the design parameters of the plurality of series arm resonators in the series arm resonator section is not particularly limited. The plurality of series arm resonators in the series arm resonator section may be connected in series to each other or in parallel to each other.

[0026] The multiple series arm resonator sections are connected in series with each other between the first signal terminal 3A and the second signal terminal 3B. More specifically, from the first signal terminal 3A side, the series arm resonator section S1, the series arm resonator section S2, the series arm resonator section S3, the series arm resonator section S4, and the series arm resonator section S5 are connected in this order.

[0027] Each of the series arm resonator sections S1 and S3 includes three split-type series arm resonators. The series arm resonator section S2 includes two split-type series arm resonators. More specifically, the series arm resonator section S1 includes a series arm resonator S1a, a series arm resonator S1b, and a series arm resonator S1c. The series arm resonator section S2 includes a series arm resonator S2a and a series arm resonator S2b. The series arm resonator section S3 includes a series arm resonator S3a, a series arm resonator S3b, and a series arm resonator S3c.

[0028] In this embodiment, only one node D is arranged between the series arm resonator sections. Note that, for example, multiple nodes D may be arranged between the series arm resonator sections. When the sections between the first signal terminal 3A and the series arm resonator section, between the second signal terminal 3B and the series arm resonator section, and between adjacent series arm resonator sections are defined as sections, it is sufficient that at least one node D is located in each section between at least adjacent series arm resonator sections.

[0029] The first filter 1A has a plurality of parallel arm resonator units. Specifically, one parallel arm resonator unit is a parallel arm resonator located in a parallel arm connected to a node D located in the same section. For example, as in this embodiment, when only one node D and only one parallel arm P are arranged in the same section, the parallel arm resonator unit is one parallel arm resonator or a group of multiple parallel arm resonators connected in series or parallel to each other in the parallel arm P. On the other hand, when multiple nodes D and multiple parallel arms P are arranged in the same section, the multiple parallel arm resonators located in the multiple parallel arms P are included in one parallel arm resonator unit.

[0030] When only one node D and only one parallel arm P are arranged in the same section, the parallel arm resonator section may be, for example, a section made up of a plurality of split-type parallel arm resonators. Hereinafter, the series arm resonator section and the parallel arm resonator section may be collectively referred to simply as the resonator section.

[0031] The multiple parallel arm resonator sections of the first filter 1A are specifically the parallel arm resonator section P1, the parallel arm resonator section P2, the parallel arm resonator section P3, and the parallel arm resonator section P4. In this embodiment, all of the parallel arm resonator sections of the first filter 1A are formed of one parallel arm resonator.

[0032] The parallel arm resonator section P1 is connected between a node D between the series arm resonator section S1 and the series arm resonator section S2 and the ground potential. The parallel arm resonator section P2 is connected between a node D between the series arm resonator section S2 and the series arm resonator section S3 and the ground potential. The parallel arm resonator section P3 is connected between a node D between the series arm resonator section S3 and the series arm resonator section S4 and the ground potential. The parallel arm resonator section P4 is connected between a node D between the series arm resonator section S4 and the series arm resonator section S5 and the ground potential.

[0033] Fig. 2 is a circuit diagram for explaining the ladder section of the first filter in the first embodiment. In Fig. 2, for convenience in explaining the ladder section described later, one series arm resonator section is indicated by the reference symbols of one or two resonators. Similarly, for convenience, one parallel arm and a parallel arm resonator section located in the parallel arm are indicated by the reference symbols of two parallel arms and two resonators.

[0034] In the following, a pair of adjacent series arm resonators and parallel arm resonators is defined as one ladder section, as indicated by the dashed lines in Fig. 2. In the first filter 1A, a plurality of ladder sections are configured between the first signal terminal 3A and the second signal terminal 3B. Specifically, eight ladder sections are configured. The first to eighth ladder sections are arranged in order from the first signal terminal 3A side to the second signal terminal 3B side.

[0035] The first ladder section is composed of the series arm resonator S1c and the parallel arm resonator of the parallel arm resonator section P1 shown in Fig. 1. The second ladder section adjacent to the first ladder section is composed of the parallel arm resonator of the parallel arm resonator section P1 and the series arm resonator S2a. The series arm resonators of these adjacent ladder sections are different from each other, but the parallel arm resonators are common to each other.

[0036] However, this is not a limitation. For example, the third ladder section shown in Fig. 2 is composed of the series arm resonator S2b and the parallel arm resonator of the parallel arm resonator section P2 shown in Fig. 1. Therefore, in the adjacent second and third ladder sections, the series arm resonators are different from each other and the parallel arm resonators are different from each other.

[0037] Alternatively, for example, the sixth ladder section shown in Fig. 2 is composed of the parallel arm resonator of the parallel arm resonator section P3 and the series arm resonator of the series arm resonator section S4. The seventh ladder section is composed of the series arm resonator of the series arm resonator section S4 and the parallel arm resonator of the parallel arm resonator section P4. Therefore, the parallel arm resonators of the sixth and seventh ladder sections adjacent to each other are different from each other, and the series arm resonator is common to both ladder sections. In this way, it is sufficient that at least one of the series arm resonators and the parallel arm resonators of the adjacent ladder sections are different from each other.

[0038] Here, the half of all the ladder sections that is located on the first signal terminal 3A side is defined as the first half of the ladder section. Among the multiple resonators, the resonators from the resonator located closest to the first signal terminal 3A side to the series arm resonators and parallel arm resonators of the ladder section located closest to the second signal terminal 3B side in the first half of the ladder section are defined as the first half of the ladder section. In this embodiment, the first half of the ladder section includes the first to fourth ladder sections. The first half of the resonators are the series arm resonators S1a, S1b, S1c, the parallel arm resonators of the parallel arm resonator section P1, the series arm resonators S2a, S2b, the parallel arm resonators of the parallel arm resonator section P2, and the series arm resonator S3a.

[0039] As described above, the multiple series arm resonators and the multiple parallel arm resonators of the first filter 1A are all elastic wave resonators. As will be described in detail later, these elastic wave resonators include excitation angle variable resonators and elastic wave resonators other than the excitation angle variable resonators. Note that in FIG. 1, the resonators surrounded by a dashed line are excitation angle variable resonators. The same applies to other schematic circuit diagrams and circuit diagrams.

[0040] A feature of this embodiment is that at least one of the first half resonators is a variable excitation angle resonator. Specifically, in this embodiment, each series arm resonator in the series arm resonator section S1 is a variable excitation angle resonator. Note that a variable excitation angle resonator is a resonator whose excitation angle changes in the crossing region. This makes it possible to suppress the influence of unwanted waves in the multiplexer 1. Details of the above effects will be described below together with the configuration of this embodiment and details of the excitation angle and the variable excitation angle resonator.

[0041] Fig. 3 is a schematic plan view of the first filter in the first embodiment. Fig. 4 is a schematic cross-sectional view along line II in Fig. 3. Fig. 5 is a schematic plan view of an excitation angle variable resonator of the first filter in the first embodiment. In Fig. 3, the IDT electrodes and a reflector, which will be described later, are shown by a simplified diagram of a figure including curves or a rectangle with two diagonal lines added. The same applies to the other schematic plan views. A dielectric film, which will be described later, is omitted in Figs. 3 and 5. The same applies to the other plan views.

[0042] As shown in FIG. 3, the first filter 1A has a piezoelectric substrate 2. The piezoelectric substrate 2 is a laminated substrate including a piezoelectric layer 6. That is, the piezoelectric substrate 2 is a substrate having piezoelectric properties. All the acoustic wave resonators in the first filter 1A share the piezoelectric substrate 2. Each acoustic wave resonator has an IDT electrode. The IDT electrode of each acoustic wave resonator is provided on the piezoelectric substrate 2.

[0043] As shown in FIG. 4, the piezoelectric substrate 2 has a support member 3 and a piezoelectric layer 6. More specifically, the support member 3 has a support substrate 4 and an intermediate layer 5. The intermediate layer 5 includes a first layer 5a and a second layer 5b. The first layer 5a is provided on the support substrate 4. The second layer 5b is provided on the first layer 5a. The piezoelectric layer 6 is provided on the second layer 5b. The layer configuration of the piezoelectric substrate 2 is not limited to the above. For example, the intermediate layer 5 may be a single-layer dielectric film. Alternatively, the piezoelectric substrate 2 may be a substrate consisting of only the piezoelectric layer 6.

[0044] In this embodiment, silicon is used as the material of the support substrate 4. Silicon nitride is used as the material of the first layer 5a. Silicon oxide is used as the material of the second layer 5b. Rotated Y-cut X-propagation lithium tantalate is used as the material of the piezoelectric layer 6. Thus, the piezoelectric layer 6 has a propagation axis. The direction of the propagation axis is the X-direction. However, the materials of each layer of the piezoelectric substrate 2 are not limited to those mentioned above.

[0045] The piezoelectric layer 6 has a first principal surface 6a and a second principal surface 6b. The first principal surface 6a and the second principal surface 6b face each other. Of the first principal surface 6a and the second principal surface 6b, the second principal surface 6b is located on the support substrate 4 side. An IDT electrode 18 of the series arm resonator S1a is provided on the first principal surface 6a of the piezoelectric layer 6. The IDT electrodes of the elastic wave resonators other than the series arm resonator S1a are also similarly provided on the first principal surface 6a.

[0046] As shown in Fig. 5, an IDT electrode 18 of a series arm resonator S1a, which is an excitation angle variable resonator, has a pair of bus bars. The pair of bus bars is specifically a first bus bar 14 and a second bus bar 15. The first bus bar 14 and the second bus bar 15 face each other. The IDT electrode 18 has a plurality of electrode fingers. The plurality of electrode fingers is specifically a plurality of first electrode fingers 16 and a plurality of second electrode fingers 17. One ends of the plurality of first electrode fingers 16 are each connected to the first bus bar 14. One ends of the plurality of second electrode fingers 17 are each connected to the second bus bar 15.

[0047] Each of the first electrode fingers 16 and the second electrode fingers 17 includes a base end, a tip end, and a pair of edge portions. Specifically, the base end of the first electrode finger 16 is a portion connected to the first bus bar 14. The pair of edge portions of the first electrode finger 16 are portions connecting the base end and the tip end. The base end of the second electrode finger 17 is a portion connected to the second bus bar 15. The pair of edge portions of the second electrode finger 17 are portions connecting the base end and the tip end in a plan view. The first electrode fingers 16 and the second electrode fingers 17 are interdigitated with each other. In this specification, a plan view refers to a view from a direction corresponding to the top in FIG. 4. In FIG. 4, for example, the piezoelectric layer 6 side is the top of the supporting substrate 4 side and the piezoelectric layer 6 side.

[0048] The tips of the first electrode fingers 16 and the second electrode fingers 17 each include a tip. An imaginary line formed by connecting the tips of the second electrode fingers 17 is a first envelope E1. Similarly, an imaginary line formed by connecting the tips of the first electrode fingers 16 is a second envelope E2. In the following, the first electrode fingers 16 and the second electrode fingers 17 may be simply referred to as electrode fingers. The first bus bar 14 and the second bus bar 15 may be simply referred to as bus bars.

[0049] The region between the first envelope E1 and the second envelope E2 is the intersection region J. More specifically, the region surrounded by an edge of an electrode finger at one end in the direction in which the electrode fingers are arranged, an edge of an electrode finger at the other end, the first envelope E1, and the second envelope E2 is the intersection region J. Thus, the first envelope E1 corresponds to the edge of the intersection region J on the first bus bar 14 side. The second envelope E2 corresponds to the edge of the intersection region J on the second bus bar 15 side. In the intersection region J, adjacent electrode fingers overlap each other when viewed from the direction in which the first envelope E1 or the second envelope E2 extends.

[0050] In this embodiment, the intersection region J is formed of one curved region. The curved region is a region in which the first electrode fingers 16 and the second electrode fingers 17 each have a curved shape in a plan view. One edge of the curved region forming the intersection region J is a first envelope E1. The other edge is a second envelope E2. In the series arm resonator S1a, which is an excitation angle variable resonator, it is sufficient that the electrode fingers are curved. For example, the shape of the electrode fingers in a plan view may be bent at multiple nodes.

[0051] An acoustic wave is excited by applying an AC voltage to the IDT electrode 18. Specifically, for example, the SH mode is excited as the main mode. In this case, the Rayleigh wave becomes an unwanted wave. However, the main mode is not limited to the SH mode.

[0052] The intersection region J of the IDT electrode 18 is a curved region. In the curved region, each electrode finger has a curved shape in a plan view. Therefore, in the curved region of the IDT electrode 18, the excitation direction of the acoustic wave is not uniform.

[0053] Specifically, in the curved region, the excitation direction of an acoustic wave in any part of any electrode finger among the multiple first electrode fingers 16 and the multiple second electrode fingers 17 is any one of the following first to third directions. The first direction is a direction perpendicular to the direction in which the electrode finger extends. The second direction is a direction connecting the electrode finger and the first electrode finger 16 or the second electrode finger 17 adjacent to the electrode finger. The third direction is a direction of an electric field vector generated between the electrode finger and the first electrode finger 16 or the second electrode finger 17 adjacent to the electrode finger.

[0054] In addition, since the shape of each electrode finger in the curved region is curved, the direction in which each electrode finger extends varies depending on the position. In this specification, unless otherwise specified, the directions in which the curved electrode fingers extend are as follows:

[0055] First, a pair of edge portions of each electrode finger has a curved shape. If an imaginary line is drawn parallel to the direction in which the propagation axis extends so as to connect both edge portions at any part of the electrode finger, the center of gravity of the part located on the imaginary line is defined as the representative point of the imaginary line. An infinite number of imaginary lines can be drawn on the electrode finger, and therefore there are an infinite number of representative points. The direction in which the tangent to the curve connecting these representative points extends is defined as the extension direction of the electrode finger.

[0056] The angle between the excitation direction of the elastic wave and the direction in which the propagation axis of the piezoelectric layer 6 extends is called the excitation angle θ C_prop In the present invention, the excitation angle variable resonator is a resonator in which the excitation angle θ C_prop In other words, in the crossing region J of the excitation angle variable resonator, the excitation angle θ C_prop However, this is not uniform.

[0057] In this embodiment, the direction in which the propagation axis extends is parallel to the direction in which the two-dot chain line N in FIG. C_prop is 0°. Excitation angle θ C_prop On the other hand, as shown by the curve M in FIG. 5, in this embodiment, the excitation angle θ C_prop is other than 0° and the excitation angle θ C_prop If the parts where the excitation angle θ is the same are connected, a curve will be formed. C_prop is other than 0° and the excitation angle θ C_prop In the curved region, there are an infinite number of curves similar to the curve M. In this way, the shapes of the first electrode fingers 16 and the second electrode fingers 17 in a plan view are the same as the excitation angle θ C_prop is other than 0° and the parts that are the same are arranged in a curved line.

[0058] In this specification, the excitation angle θ C_propThe positive direction in the graph is the counterclockwise direction in a plan view. More specifically, the direction from second bus bar 15 to first bus bar 14 is the positive direction. In the following, unless otherwise specified, the direction in which the electrode fingers are curved to be convex is the outward direction. For example, the rightward direction in FIG. 5 is the outward direction of IDT electrode 18. The direction opposite to the outward direction is the inward direction. For example, the leftward direction in FIG. 5 is the inward direction of IDT electrode 18.

[0059] In the IDT electrode 18 of this embodiment, the excitation angle θ C_prop The electrode finger pitch and duty ratio are constant in the portions where the electrode finger pitch is the same. The electrode finger pitch is the center-to-center distance between adjacent first electrode fingers 16 and second electrode fingers 17. When the wavelength defined by the electrode finger pitch of IDT electrode 18 is λ and the electrode finger pitch is p, λ=2p.

[0060] The first envelope E1 in the series arm resonator S1a has a plurality of portions inclined with respect to the propagation axis. The first envelope E1 has a plurality of bent portions V1. More specifically, the bent portions are portions where the direction in which the envelope extends changes. In this embodiment, the first envelope E1 has a wavy shape in which adjacent bent portions V1 are connected by straight lines. The first envelope E1 may have a wavy shape in which adjacent bent portions V1 are connected by curved lines.

[0061] Similarly, the second envelope E2 also has a plurality of portions that are inclined with respect to the propagation axis. The second envelope E2 has a plurality of bent portions V2. The shape of the second envelope E2 is a wavy shape in which adjacent bent portions V2 are connected by straight lines. Note that the shape of the second envelope E2 may also be a wavy shape in which adjacent bent portions V2 are connected by curved lines.

[0062] As described above, in this embodiment, both the first envelope E1 and the second envelope E2 have multiple bends. However, at least one of the first envelope E1 and the second envelope E2 may have at least one bend.

[0063] The IDT electrode 18 has a plurality of segments, each of which is bounded by an electrode finger passing through the bent portion V1 of the first envelope E1. The plurality of segments are aligned in the direction in which the propagation axis extends. In FIG. 5, four segments are shown diagrammatically.

[0064] The excitation angle θ of the end of the first envelope E1 or the part located at the bend V1 C_prop The first envelope excitation angle θ C_AP1_m m is a natural number. The first envelope excitation angle θ C_AP1_m can be defined for the end of the first envelope E1 or each bent portion V1. Specifically, the excitation angle θ on the first envelope is defined in the order from the end and bent portion V1 on the inside of the IDT electrode 18. C_AP1_m In this way, m is set to 1, 2, 3, etc. The excitation angle θ C_AP1_m For example, the excitation angle θ of the part located at the inner end is C_prop The first envelope excitation angle θ C_AP1_1 The excitation angle θ at the innermost bend V1 C_prop The first envelope excitation angle θ C_AP1_2 It is.

[0065] Similarly, the excitation angle θ of the portion located at the end of the second envelope E2 or the bend V2 C_prop The second envelope excitation angle θ C_AP2_m The excitation angle θ on the second envelope of the part located inside C_AP2_m The value of m is assumed to be smaller.

[0066] As described above, four segments are shown diagrammatically in Fig. 5. However, the IDT electrode 18 has five segments. Here, the five segments in the IDT electrode 18 are diagrammatically shown in Fig. 6. In this embodiment, m is a value not less than 1 and not more than 6.

[0067] As shown in Fig. 5, the IDT electrode 18 has a plurality of offset electrodes. The plurality of offset electrodes are specifically a plurality of first offset electrodes 12 and a plurality of second offset electrodes 13. One ends of the plurality of first offset electrodes 12 are connected to a first bus bar 14. The first electrode fingers 16 and the first offset electrodes 12 are arranged alternately. One ends of the plurality of second offset electrodes 13 are connected to a second bus bar 15. The second electrode fingers 17 and the second offset electrodes 13 are arranged alternately.

[0068] Like the first electrode fingers 16 and the second electrode fingers 17, the first offset electrodes 12 and the second offset electrodes 13 each include a base end and a tip end. The base ends of the first electrode fingers 16 and the first offset electrode 12 are connected to the first bus bar 14. The base ends of the second electrode fingers 17 and the second offset electrode 13 are connected to the second bus bar 15. The tip end of the first electrode finger 16 and the tip end of the second offset electrode 13 face each other across a gap. The tip end of the second electrode finger 17 and the tip end of the first offset electrode 12 face each other across a gap.

[0069] It is not necessary to provide the first offset electrodes 12 and the second offset electrodes 13. Hereinafter, the first offset electrodes 12 and the second offset electrodes 13 may be simply referred to as offset electrodes. The shape of each of the offset electrodes in a plan view includes a curved portion.

[0070] A pair of reflectors 9A and 9B are provided on the piezoelectric layer 6. The reflectors 9A and 9B face each other with the IDT electrode 18 therebetween in the direction in which the electrode fingers of the IDT electrode 18 are arranged.

[0071] The reflector 9A has a pair of reflector bus bars 9a and 9b. The reflector bus bars 9a and 9b face each other. The reflector 9A has a plurality of reflector electrode fingers 9c. One ends of the plurality of reflector electrode fingers 9c are connected to the reflector bus bar 9a. The other ends of the plurality of reflector electrode fingers 9c are connected to the reflector bus bar 9b. The shape of each of the plurality of reflector electrode fingers 9c of the reflector 9A in a plan view includes a curved shape.

[0072] Similarly, the reflector 9B has a pair of reflector bus bars 9d and 9e, and a plurality of reflector electrode fingers 9f. The IDT electrode 18, the reflector 9A, and the reflector 9B are made of a single-layer metal film. Specifically, in this embodiment, the IDT electrode 18, the reflector 9A, and the reflector 9B are made of Al. The materials of the IDT electrode 18, the reflector 9A, and the reflector 9B are not limited to those mentioned above. Alternatively, the IDT electrode 18, the reflector 9A, and the reflector 9B may be made of a laminated metal film.

[0073] In the piezoelectric layer 6 of the first filter 1A, the direction in which the propagation axis extends is the X-propagation direction. However, this is not limited to this direction. The direction in which the propagation axis extends may be, for example, the 90° X-propagation direction, or may be a direction perpendicular to any of the directions in which the electrode fingers of the IDT electrode 18 extend.

[0074] 4, a dielectric film 8 is provided on the piezoelectric layer 6 so as to cover the IDT electrode 18. The IDT electrode 18 is protected by the dielectric film 8, so that the IDT electrode 18 is less likely to be damaged. In this embodiment, silicon oxide is provided as the material of the dielectric film 8. Note that the material of the dielectric film 8 is not limited to the above.

[0075] The dielectric film 8 also covers the IDT electrodes of the acoustic wave resonators other than the series arm resonator S1a. In this embodiment, the thickness of the dielectric film 8 is constant. A configuration in which the dielectric film 8 is provided can also be adopted in other embodiments of the present invention besides this embodiment. Note that the dielectric film 8 is not necessarily provided.

[0076] As described above, in the first filter 1A, the series arm resonators S1a, S1b, and S1c of the series arm resonator section S1 shown in Fig. 1 are variable excitation angle resonators. The configuration of the series arm resonator S1a has been described using Fig. 5 and other figures, but the series arm resonators S1b and S1c are also configured in the same manner as the series arm resonator S1a. In this embodiment, each series arm resonator in the series arm resonator section S1 is a series-divided resonator and has the same design parameters. However, the design parameters may be appropriately different between these series arm resonators.

[0077] On the other hand, the resonators other than the series arm resonators in the series arm resonator section S1 are not variable excitation angle resonators.The configuration of the series arm resonator S2a is shown as an example.

[0078] FIG. 7 is a schematic plan view of an elastic wave resonator other than an excitation angle variable resonator of a first filter according to the first preferred embodiment.

[0079] In the series arm resonator S2a, the shape of each electrode finger of the IDT electrode 18A is linear. Therefore, in the crossing region, the excitation angle is θ C_prop is constant. Specifically, the excitation angle is θ C_prop is 0°. The first envelope E1A and the second envelope E2A of the IDT electrode 18A are inclined with respect to the propagation axis. The first bus bar 14A and the second bus bar 15A have a linear shape. In this manner, the IDT electrode 18A is an inclined IDT electrode. The reflector 9C and the reflector 9D of the series arm resonator S2a have a linear shape.

[0080] In this preferred embodiment, the elastic wave resonators other than the excitation angle variable resonator are configured similarly to the series arm resonator S2a, although the design parameters of each of the elastic wave resonators other than the excitation angle variable resonator are appropriately set.

[0081] As described above, in the first filter 1A of the multiplexer 1, among the first half resonators, each series arm resonator in the series arm resonator section S1 shown in Fig. 1 is an excitation angle variable resonator. This makes it possible to suppress the influence of spurious waves in the multiplexer 1. The details of this will be described below by comparing this embodiment with the first comparative example.

[0082] The first comparative example differs from the first embodiment in that all the elastic wave resonators are configured similarly to the elastic wave resonators shown in FIG. 7. The circuit configuration of the multiplexer in the first comparative example is similar to that in the first embodiment. The attenuation frequency characteristics were compared between the second filter 1B in the first embodiment and the second filter in the first comparative example. The attenuation frequency characteristics of each filter in the first embodiment are also shown.

[0083] The design parameters of the excitation angle variable resonator in the first embodiment are as follows. Here, the dimension along the direction connecting the base end and the tip end of the offset electrode is defined as the length of the offset electrode. The dimension of the gap between the tip end of the electrode finger and the tip end of the offset electrode along the direction in which the electrode finger and the offset electrode face each other is defined as the gap length. In this embodiment, the gap between the tip end of second electrode finger 17 and the tip end of first offset electrode 12 and the gap between the tip end of first electrode finger 16 and the tip end of second offset electrode 13 have the same gap length.

[0084] Support substrate 4: Material: Si, surface orientation: (100), Euler angles (φ, θ, ψ) ψ: 45° First layer 5a of intermediate layer 5: Material: SiN, thickness: 0.514λ Second layer 5b of intermediate layer 5: Material: SiO2, thickness: 0.384λ Piezoelectric layer 6: Material: Rotated Y-cut 50° X-propagation LiTaO3, thickness: 0.343λ IDT electrode 18: Material: Al, thickness: 0.05λ Dielectric film 8: Material: SiO2, thickness: 0.02λ Wavelength λ: Excitation angle θ C_prop 1.7509μm at 0° Number of pairs of electrode fingers of IDT electrode 18: 100 pairs Duty ratio: 0.5 Gap length: 0.135λ Offset electrode length: 3.5λ Distance between the first envelope E1 and the second envelope E2 in a direction perpendicular to the propagation axis: 25λ First envelope E1: absolute value of the inclination angle with respect to the propagation axis... 20°, number of pairs of electrode fingers between bends V1... 20 pairs Second envelope E2: absolute value of inclination angle with respect to the propagation axis: 20°, number of pairs of electrode fingers between bends V2: 20 pairs First envelope excitation angle: θ C_AP1_1 = 12°, θ C_AP1_2 = 8°, θ C_AP1_3 = 16°, θ C_AP1_4 = 10°, θ C_AP1_5 = 16°, θ C_AP1_6 =9° Second envelope excitation angle: θ C_AP2_1 = 9°, θ C_AP2_2 = 15°, θ C_AP2_3 = 8°, θ C_AP2_4 = 15.5°, θ C_AP2_5 = 10°, θ C_AP2_6 =16° Reflector 9A and reflector 9B: Number of pairs of reflector electrode fingers...20 pairs

[0085] In the first embodiment and the first comparative example, the IDT electrodes in the acoustic wave resonators other than the IDT electrodes in the excitation angle varying resonators are inclined IDT electrodes. In the inclined IDT electrodes in the first embodiment and the first comparative example, the absolute value of the inclination angle with respect to the propagation angle of the first envelope and the second envelope is 7.5°.

[0086] Fig. 8 is a diagram showing the attenuation frequency characteristics of the first filter, the second filter, the third filter, and the fourth filter in the first embodiment, and Fig. 9 is a diagram showing the attenuation frequency characteristics of the second filter in the first embodiment and the first comparative example.

[0087] As shown in FIG. 8, the insertion loss of each filter in the first embodiment is sufficiently small.

[0088] As shown in FIG. 9, in the attenuation frequency characteristic of the second filter in the first comparative example, large ripples occur within the passband. In contrast, in the attenuation frequency characteristic of the second filter in the first embodiment, the ripples are suppressed within the passband. The above-mentioned ripples are caused by unwanted waves generated in the acoustic wave resonator of the first filter. In the first embodiment, since the unwanted waves can be suppressed, it is possible to prevent the insertion loss of the second filter from becoming large. The reason for this is as follows.

[0089] In the crossing region J of the series arm resonator S1a shown in FIG. 5, the excitation angle θ C_prop is other than 0° and the excitation angle θ C_prop An infinite number of curved portions having the same excitation angle θ are arranged in the direction in which first bus bar 14 and second bus bar 15 face each other. C_prop are different. Excitation angle θ C_prop In the portions where the frequencies are different from each other, the propagation characteristics of the unwanted waves are different from each other. This makes it possible to disperse the unwanted waves and effectively suppress the unwanted waves. In particular, it is possible to suppress the unwanted waves outside the band. In this specification, "outside the band" in the elastic wave device refers to the lower frequency side than the resonant frequency and the higher frequency side than the anti-resonant frequency.

[0090] Furthermore, when an unwanted wave occurs in an acoustic wave resonator near the common connection terminal 7 shown in Fig. 1 in the first filter 1A or the like, the unwanted wave has a large effect on the other filters. Here, as described above, of all the ladder sections shown in Fig. 2, the half of the ladder section located on the first signal terminal 3A side is the first half ladder section. On the other hand, the ladder section located on the second signal terminal 3B side of the first half ladder section is the second half ladder section. The two-dot chain line in Figs. 1 and 2 indicates the boundary between the first half ladder section and the second half ladder section.

[0091] Among the multiple resonators, the first half resonators include the resonator located closest to the first signal terminal 3A to the series arm resonator and parallel arm resonator of the ladder section located closest to the second signal terminal 3B in the first half ladder section. When spurious waves are generated in these first half resonators, the influence of the spurious waves on other filters is particularly large.

[0092] In the first embodiment, the series arm resonators S1a, S1b, and S1c, which are the first half resonators, are variable excitation angle resonators. This makes it possible to suppress unwanted waves outside the band in the three first half resonators. Therefore, it is possible to suppress ripples in the second filter 1B caused by unwanted waves. However, it is sufficient that at least one of the first half resonators is a variable excitation angle resonator.

[0093] In addition, all resonators other than the first resonator are elastic wave resonators that are not excitation angle variable resonators. Specifically, in all resonators other than the first resonator, the excitation angle θ C_prop is constant. As a result, in these resonators, the resonant frequency and the anti-resonant frequency can be easily matched in all crossing regions, and the resonance characteristics can be easily improved. Therefore, the filter characteristics of the first filter 1A can be easily and effectively improved. Moreover, even if spurious waves are generated in these resonators, the effect on other filters is small.

[0094] Here, it will be specifically shown that the excitation angle variable resonator can suppress unnecessary waves outside the band. The phase characteristics of the excitation angle variable resonator and the elastic wave resonator shown in FIG. 7 were compared. In this comparison, neither resonator has the dielectric film 8 shown in FIG. 4. The design parameters of the excitation angle variable resonator are shown below. The design parameters of the excitation angle variable resonator are the same as those of the excitation angle variable resonator in the comparison shown in FIG. 9 in terms of the first envelope E1, the second envelope E2, the excitation angle on the first envelope, the excitation angle on the second envelope, and the number of pairs of reflector electrode fingers.

[0095] Support substrate: Material: Si, surface orientation: (100), Euler angles (φ, θ, ψ) are 45° First intermediate layer: Material: SiN, thickness: 0.45λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.337λ Piezoelectric layer: Material: Rotated Y-cut 50°X-propagation LiTaO3, thickness: 0.3λ IDT electrode: Material: Al, thickness: 0.07λ Wavelength λ: Excitation angle θ C_prop 2μm at 0° Number of pairs of IDT electrode fingers: 100 pairs Duty ratio: 0.5 Gap length: 0.135λ Offset electrode length: 3.5λ Distance between the first envelope E1 and the second envelope E2 in a direction perpendicular to the propagation axis: 25λ

[0096] In an inclined IDT electrode in an elastic wave resonator that is not an excitation angle variable resonator, the absolute value of the inclination angle with respect to the propagation angle of the first envelope and the second envelope is 7.5°. The duty ratio is 0.5. The number of pairs of electrode fingers in the IDT electrode is 100. The dimension of the intersection region along the extension direction of the multiple electrode fingers is 25λ.

[0097] FIG. 10 is a diagram showing phase characteristics of an excitation angle changing resonator and an elastic wave resonator having an inclined IDT electrode.

[0098] As shown in Fig. 10, in an elastic wave resonator having an inclined IDT electrode, large unwanted waves are generated near the frequencies indicated by arrows T1, T2, T3, and T4. The frequency indicated by arrow T1 is a frequency lower than the resonant frequency. The unwanted waves generated near the frequency indicated by arrow T1 are Rayleigh waves. On the other hand, the frequencies indicated by arrows T2, T3, and T4 are frequencies higher than the anti-resonant frequency.

[0099] As shown in FIG. 10, in the excitation angle variable resonator, it is understood that spurious waves can be suppressed near any of the frequencies indicated by the arrows T1, T2, T3, and T4.

[0100] In the first embodiment, all three series arm resonators in the series arm resonator section S1 are variable excitation angle resonators. Here, only the number and arrangement of the variable excitation angle resonators in the series arm resonator section S1 were changed to study the effect on suppression of spurious waves. Specifically, the above study was performed for the first embodiment and the first to fourth modified examples of the first embodiment.

[0101] More specifically, in the first modified example, only the series arm resonator S1a is an excitation angle variable type resonator. In the second modified example, the series arm resonators S1a and S1b are excitation angle variable type resonators. In the third modified example, only the series arm resonator S1c is an excitation angle variable type resonator. In the fourth modified example, the series arm resonators S1b and S1c are excitation angle variable type resonators.

[0102] In the first embodiment, its first to fourth modifications, and the first comparative example, the return losses on the common connection terminal 7 side of the first filter were compared.

[0103] Fig. 11 is a diagram showing return losses in the first embodiment and its first to fourth modifications and a first comparative example. The symbols in parentheses in Fig. 11 indicate the symbols of the series arm resonators which are excitation angle variable resonators.

[0104] Table 1 shows the return loss of unwanted waves occurring near 1725 MHz in the first embodiment, its first to fourth modifications, and the first comparative example. Note that 1725 MHz is a frequency lower than the resonant frequency of each series arm resonator in the series arm resonator section S1. Therefore, the unwanted waves are out-of-band unwanted waves.

[0105] [Table 1]

[0106] 11 and Table 1, in the first comparative example, the absolute value of the return loss of the unwanted waves occurring near 1725 MHz is as large as 5.7 dB. On the other hand, in the first embodiment and its first to fourth modified examples, it is found that the unwanted waves are suppressed.

[0107] The series arm resonator section S1 includes three excitation angle variable resonators in the first embodiment, two in the second and fourth modifications, and one in the first and third modifications. In the first embodiment, the absolute value of the return loss of the unwanted waves is small, 1.74 dB. In the second and fourth modifications, the absolute value of the return loss of the unwanted waves is 2.52 dB. In the first and third modifications, the absolute value of the return loss of the unwanted waves is 4.3 dB. These results show that the more excitation angle variable resonators the series arm resonator section S1 includes, the more the unwanted waves generated around 1725 MHz are suppressed.

[0108] Note that the first and third modified examples have different arrangements of the excitation angle variable resonators. However, the above-mentioned unwanted waves are suppressed to the same extent in the first and third modified examples. The second and fourth modified examples have different arrangements of the excitation angle variable resonators. However, the above-mentioned unwanted waves are suppressed to the same extent in the second and fourth modified examples. As such, it can be seen that the number of excitation angle variable resonators in the series arm resonator section S1 has a greater effect on the suppression of out-of-band unwanted waves than the arrangement of the excitation angle variable resonators in the series arm resonator section S1.

[0109] In the filter, in the first half ladder section and in a portion of the second half ladder section that includes only the first half ladder section, when the series arm resonator section includes a plurality of series arm resonators, it is preferable that half or more of the series arm resonators in the series arm resonator section are variable excitation angle resonators. It is more preferable that all of the series arm resonators in the series arm resonator section are variable excitation angle resonators. This makes it possible to effectively suppress unwanted waves outside the band. This makes it possible to effectively suppress the influence of unwanted waves on the second filter 1B as another filter.

[0110] As in the first embodiment, it is preferable that at least one series arm resonator in the series arm resonator section S1 located closest to the first signal terminal 3A among the multiple series arm resonator sections is a variable excitation angle resonator. It is more preferable that half or more of the series arm resonators in the series arm resonator section S1 are variable excitation angle resonators, and it is even more preferable that all of the series arm resonators in the series arm resonator section S1 are variable excitation angle resonators. This makes it possible to effectively suppress the influence of unwanted waves on other filters.

[0111] In the following further details of the first embodiment are given.

[0112] As shown in FIG. 5 , the adjacent portion of the first electrode finger 16 includes a portion of the first electrode finger 16 that is located on the first envelope E1 and is adjacent to the tip of any of the second electrode fingers 17. The adjacent portion of the second electrode finger 17 includes a portion of the second electrode finger 17 that is located on the second envelope E2 and is adjacent to the tip of any of the first electrode fingers 16. The tip of the electrode finger is defined as a portion within a range of about 1λ along the direction in which the electrode fingers extend. The range of the adjacent portion is also defined as a range of about 1λ along the direction in which the electrode fingers extend. The electrode finger pitch that serves as the reference for the range of the tip and adjacent portions is, for example, an excitation angle θ C_prop The electrode finger pitch may be the narrowest in the portion where the angle is 0°.

[0113] In the series arm resonator S1a as the excitation angle variable resonator of the first embodiment, the shape of the first electrode fingers 16 and the second electrode fingers 17 in a plan view is a shape with a gently changing curvature. Specifically, the shape of the first electrode fingers 16 and the second electrode fingers 17 in a plan view is a shape that can be approximated to a circular arc. However, for example, the shape of the first electrode fingers 16 and the second electrode fingers 17 in a plan view may be a shape that can be approximated to an elliptical arc. Note that the shape of each electrode finger in a plan view does not necessarily have to be a shape that can be approximated to a circular arc or an elliptical arc. For example, the shape of each electrode finger in a plan view may be a parabola that cannot be approximated to a circular arc or an elliptical arc.

[0114] The following describes configurations that are preferably established in at least one excitation angle variable resonator of the present invention.

[0115] It is preferable that all the electrode fingers in the IDT electrode 18 have curved shapes different from one another in a plan view. Three types of examples are specifically shown. As an example of the first type, it is preferable that the curvatures be different between the tips, adjacent portions, or tips and adjacent portions of all the first electrode fingers 16 and all the second electrode fingers 17 located on the first envelope curve E1 side. More specifically, it is preferable that the curvatures be different between the tips of all the second electrode fingers 17, between adjacent portions of all the first electrode fingers 16, and between the tips of all the second electrode fingers 17 and the adjacent portions of all the first electrode fingers 16.

[0116] As an example of the second type, it is preferable that the curvatures be different between the tips, between the adjacent parts, or between the tips and the adjacent parts located on the second envelope E2 side of all first electrode fingers 16 and all second electrode fingers 17. More specifically, it is preferable that the curvatures be different between the tips of all first electrode fingers 16, between the adjacent parts of all second electrode fingers 17, and between the tips of all first electrode fingers 16 and the adjacent parts of all second electrode fingers 17.

[0117] As an example of the third type, the excitation angle θ C_prop It is preferable that the curvature differs between the portions located in the portion where the angle is 0°. In this manner, by having all the electrode fingers of the IDT electrode 18 have mutually different curved shapes in a plan view, it is possible to more reliably and effectively suppress unwanted waves.

[0118] The first embodiment satisfies all of the above three examples, provided that in at least one pair of electrode fingers among the plurality of first electrode fingers 16 and the plurality of second electrode fingers 17, the curvatures between the tip ends located on the first envelope curve E1 side, between the adjacent portions, or between the tip ends and the adjacent portions are different from each other.

[0119] In the first embodiment, in the curved region, the shape of the multiple electrode fingers in a planar view is a curve that is neither a circular arc nor an elliptical arc. The shape of the multiple electrode fingers in a planar view is a shape that can be approximated to a circular arc. In other words, the shape of the multiple electrode fingers appears to be approximated to a circular arc when viewed in a planar view. In addition, the shapes of the multiple electrode fingers in a planar view are mutually different curved shapes. Therefore, the relationship shown in FIG. 12 is established.

[0120] FIG. 12 is a schematic plan view showing a circle including an arc when the shape of an electrode finger in a plan view of an IDT electrode according to the first embodiment is approximated to the arc.

[0121] 12, two circles R1 and R2 are indicated by dashed lines. The circles R1 and R2 are circles that include arcs when the shapes of two different electrode fingers in a plan view are approximated to arcs. The position of the center O1 of the circle R1 and the position of the center O2 of the circle R2 are different from each other.

[0122] In the curved region, when the shapes of all the first electrode fingers 16 and all the second electrode fingers 17 in a plan view are approximated to arcs, it is preferable that the positions of the centers of the circles including the arcs are different from each other. In this case, as described above, the shapes of all the electrode fingers in the IDT electrode 18 in a plan view are different curved shapes from each other. This makes it possible to more reliably and effectively suppress unwanted waves. However, in the curved region, it is only necessary that when the shapes of at least one set of electrode fingers among the plurality of first electrode fingers 16 and the plurality of second electrode fingers 17 in a plan view are approximated to arcs, the positions of the centers of the circles including the arcs are different from each other.

[0123] In the curved region, the shapes of the first electrode fingers 16 and the second electrode fingers 17 in a plan view may be approximated to elliptical arcs. In this case, it is preferable that, when the shapes of all the first electrode fingers 16 and all the second electrode fingers 17 in a plan view are approximated to elliptical arcs in the curved region, the positions of the midpoints of the foci of the ellipses including the elliptical arcs are different from each other. However, it is only necessary that, when the shapes of at least one set of electrode fingers among the first electrode fingers 16 and the second electrode fingers 17 in a plan view are approximated to elliptical arcs in the curved region, the positions of the midpoints of the foci of the ellipses including the elliptical arcs are different from each other.

[0124] It is preferable that the resonance frequencies or anti-resonance frequencies of the main mode of at least one excitation angle variable resonator such as the series arm resonator S1a substantially match each other in all of the crossing regions J. It is more preferable that the resonance frequencies or anti-resonance frequencies of all of the excitation angle variable resonators substantially match each other in each of the crossing regions J. The excitation angle θ of the excitation angle variable resonator C_prop In the portions where the excitation angle θ is different from each other, the relationship between the resonance frequencies of the main mode and the spurious waves and the relationship between the anti-resonance frequencies are different from each other. Therefore, when the resonance frequency or the anti-resonance frequency of the main mode is the same in all of the crossing regions J of the excitation angle variable resonator, C_prop In the portions where the frequencies are different from each other, the frequencies of the spurious waves are different from each other. This disperses the spurious waves outside the band. Therefore, the spurious waves outside the band, such as Rayleigh waves, can be further suppressed.

[0125] In addition, since the resonant frequencies or anti-resonant frequencies in the crossing region J are substantially the same, the main mode is preferably excited. This makes it possible to more reliably improve the resonance characteristics. This makes it possible to more reliably improve the filter characteristics of the first filter 1A in the multiplexer 1.

[0126] In this specification, the expression "one frequency and the other frequency are substantially the same" means that the absolute value of the difference between the two frequencies is 2% or less with respect to the reference frequency. C_prop This refers to the frequency when is 0°.

[0127] In the crossing region J of the excitation angle variable resonator, it is preferable that the absolute value of the difference between the highest resonance frequency and the lowest resonance frequency of the main mode is 1% or less with respect to the reference frequency. Alternatively, it is preferable that the absolute value of the difference between the highest anti-resonance frequency and the lowest anti-resonance frequency of the main mode is 1% or less with respect to the reference frequency in the crossing region J of the excitation angle variable resonator. This makes it possible to more reliably improve the resonance characteristics.

[0128] For example, in the series arm resonator S1a, at least one of the duty ratio, the electrode finger pitch, and the thicknesses of the first electrode fingers 16 and the second electrode fingers 17 is set to a value that is smaller than the excitation angle θ C_prop It is preferable that at least one of these parameters is changed according to the excitation angle θ so that the resonance frequency or the anti-resonance frequency is approximately equal in at least a part of the intersection region J. C_prop It is preferable that at least one of these parameters is changed according to the excitation angle θ so that the resonance frequency or anti-resonance frequency is approximately the same in the entire intersection region J. C_prop It is more preferable that the excitation angle is changed according to the excitation angle. This makes it possible to more reliably improve the resonance characteristics of the excitation angle variable resonator.

[0129] Alternatively, when the thickness of the intermediate layer 5 in the piezoelectric substrate 2 or the like affects the frequency, the parameter is set to the excitation angle θ C_prop In the case where the dielectric film 8 is provided on the piezoelectric substrate 2 so as to cover the IDT electrodes 18 as in the first embodiment, the thickness of the dielectric film may be changed in accordance with the excitation angle θ C_propA plurality of parameters among the parameters of the IDT electrode 18 or parameters other than the IDT electrode 18 may be changed in accordance with the excitation angle θ C_prop Even in these cases, the resonant frequency or anti-resonant frequency can be made substantially the same in at least a part or the entirety of the intersection region J.

[0130] The excitation angle θ of the IDT electrode 18 C_prop In the portion where the excitation angle θ is the same, it is preferable that at least one of the electrode finger pitch and the duty ratio is constant. C_prop It is more preferable that both the electrode finger pitch and the duty ratio are constant in the portion where the electrode finger pitch and duty ratio are the same, thereby making it possible to more reliably improve the resonance characteristics of the excitation angle variable resonator.

[0131] Examples of materials for each member of the piezoelectric substrate 2 are given below.

[0132] As the material of the support substrate 4 shown in FIG. 4, for example, a piezoelectric material such as aluminum nitride, lithium tantalate, lithium niobate, or quartz; a ceramic material such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, or sialon; a dielectric material such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), or diamond; or a semiconductor material such as silicon; or a material mainly composed of the above materials may be used. The spinel includes an aluminum compound containing one or more elements selected from Mg, Fe, Zn, Mn, and the like, and oxygen. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4. The support substrate 4 is preferably made of high-resistance silicon. The material of the support substrate 4 desirably has a volume resistivity of 1000 Ω·cm or more. In the first embodiment, high-resistance silicon is used as the material of the support substrate 4.

[0133] The first layer 5a of the intermediate layer 5 is a high acoustic velocity film. A high acoustic velocity film is a film with a relatively high acoustic velocity. More specifically, the acoustic velocity of the bulk wave propagating through the high acoustic velocity film is higher than the acoustic velocity of the elastic wave propagating through the piezoelectric layer 6. The material of the first layer 5a, which is a high acoustic velocity film, may be, for example, a piezoelectric material such as aluminum nitride, lithium tantalate, lithium niobate, or quartz; a ceramic material such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, or sialon; a dielectric material such as aluminum oxide, silicon oxynitride, DLC (diamond-like carbon), or diamond; or a semiconductor material such as silicon; or a material mainly composed of the above-mentioned material. The spinel includes an aluminum compound containing one or more elements selected from Mg, Fe, Zn, Mn, and the like, and oxygen. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4. In the first embodiment, silicon nitride is used as the material for the first layer 5a.

[0134] The second layer 5b of the intermediate layer 5 is a low acoustic velocity film. The low acoustic velocity film is a film with a relatively low acoustic velocity. More specifically, the acoustic velocity of the bulk wave propagating through the low acoustic velocity film is lower than that of the bulk wave propagating through the piezoelectric layer 6. The material of the second layer 5b, which is a low acoustic velocity film, can be, for example, a dielectric material such as glass, silicon oxide, silicon oxynitride, lithium oxide, tantalum oxide, or a compound of silicon oxide with fluorine, carbon, or boron added, or a material containing the above material as a main component. In the first embodiment, silicon oxide is used as the material of the second layer 5b.

[0135] 4 may be made of, for example, lithium tantalate, lithium niobate, zinc oxide, aluminum nitride, quartz crystal, or PZT (lead zirconate titanate). It is preferable to use lithium tantalate or lithium niobate as the material for the piezoelectric layer 6. In the first embodiment, lithium tantalate is used as the material for the piezoelectric layer 6.

[0136] In the first embodiment, a first layer 5a serving as a high acoustic velocity film, a second layer 5b serving as a low acoustic velocity film, and a piezoelectric layer 6 are laminated in this order in the piezoelectric substrate 2. This allows the energy of the elastic wave to be effectively trapped on the piezoelectric layer 6 side.

[0137] The IDT electrode 18, the reflector 9A, and the reflector 9B may be made of one or more metals selected from the group consisting of Ti, Mo, Ru, W, Al, Pt, Ir, Cu, Cr, and Sc. The IDT electrode 18 and each reflector may be made of a single-layer metal film or a multilayer metal film. In the first embodiment, the IDT electrode 18, the reflector 9A, and the reflector 9B are made of Al.

[0138] In this specification, the term "main component" refers to a component that accounts for more than 50% by weight. The main component material may be in any one of single crystal, polycrystalline, and amorphous states, or a mixture of these states.

[0139] As shown in FIG. 5, the first envelope E1 of the IDT electrode 18 has a plurality of bent portions V1. However, the first envelope E1 may have a straight shape without the bent portions V1. The first envelope E1 may extend parallel to the direction in which the propagation axis extends. Similarly, the second envelope E2 may have a straight shape without the bent portions V2. The second envelope E2 may extend parallel to the direction in which the propagation axis extends.

[0140] In this embodiment, the intersection region J includes only one curved region. However, the intersection region J may include a plurality of curved regions.

[0141] Returning to FIG. 1, the second filter 1B, the third filter 1C, and the fourth filter 1D each have a substrate different from the piezoelectric substrate of the first filter 1A. That is, each filter has an individual piezoelectric substrate. And each of these filters is configured as an individual element chip. More specifically, the first filter 1A has a WLP (Wafer Level Package) structure. The same is true for each of the other filters. The multiplexer 1 has a mounting substrate, not shown. The first filter 1A, the second filter 1B, the third filter 1C, and the fourth filter 1D are mounted on the mounting substrate.

[0142] The multiplexer 1 may have a CSP (Chip Size Package) structure. Specifically, for example, at least one of the first filter 1A, the second filter 1B, the third filter 1C, and the fourth filter 1D may be mounted on a mounting board using a conductive adhesive provided on each terminal.

[0143] 1 is provided on a mounting board. A first signal terminal 3A of the first filter 1A is electrically connected to the common connection terminal 7 by wiring or the like. Similarly, one signal terminal of each of the other filters is electrically connected to the common connection terminal 7 by wiring or the like.

[0144] All the resonators in the first filter 1A share the same piezoelectric substrate 2. However, each resonator in the first filter 1A may have a separate piezoelectric substrate. Alternatively, some of all the resonators may share one piezoelectric substrate, and the remaining resonators may share another piezoelectric substrate. For example, a plurality of excitation angle variable resonators may share one piezoelectric substrate, and a plurality of resonators that are not excitation angle variable resonators may share another piezoelectric substrate. The same applies to each filter other than the first filter 1A.

[0145] In addition, in a multiplexer, multiple filters may share the same piezoelectric substrate, in which case all resonators of the multiple filters are constructed on the same piezoelectric substrate.

[0146] In the first embodiment, the passband of the first filter 1A is located higher than the passband of the second filter 1B. In this case, it is preferable that the passband of the second filter 1B includes at least a part of frequencies that are 0.5 to 0.9 times the resonant frequency of the excitation angle variable resonator of the first filter 1A. In the above frequency range, the unwanted waves can be more reliably suppressed in the excitation angle variable resonator of the first filter 1A. Therefore, the influence of the unwanted waves on the second filter 1B can be more reliably suppressed.

[0147] On the other hand, the passband of the first filter 1A may be located lower than the passband of the second filter 1B. In the excitation angle variable resonator of the first filter 1A, it is possible to suppress spurious waves occurring at a frequency higher than the anti-resonance frequency. Therefore, it is possible to more reliably suppress the influence of spurious waves on the second filter 1B.

[0148] Below, fifth to twelfth modified examples of the first embodiment are shown, which differ from the first embodiment only in the configuration of the IDT electrodes and each reflector in the excitation angle variable resonator. In the first filter of the fifth to twelfth modified examples, excitation angle variable resonators are arranged as in the first embodiment. In the excitation angle variable resonator, unwanted waves outside the band can be suppressed. Therefore, in the multiplexers of the fifth to twelfth modified examples, the influence of unwanted waves can also be suppressed, and the insertion loss in each filter can be prevented from becoming small.

[0149] FIG. 13 is a schematic plan view of an excitation angle variable resonator of a first filter in a fifth modified example of the first embodiment.

[0150] In this modification, the shape of the first electrode fingers 16B and the second electrode fingers 17B of the IDT electrode 18B is a circular arc in a plan view. The shape of the electrode fingers in a plan view may include an elliptical arc shape.

[0151] In the IDT electrode 18B, the shapes of the electrode fingers in a plan view correspond to the respective arcs of the multiple concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the multiple electrode fingers coincide with each other. The two-dot chain line N1 in FIG. 13 is a straight line passing through the center and the intersection region J. More specifically, the two-dot chain line N1 passes through the center of the intersection region J. In this modification, the two-dot chain line N1 extends parallel to the direction in which the propagation axis extends.

[0152] When the ellipse coefficient of a circle or ellipse including arcs in the shape of multiple electrode fingers is α2 / α1, the ellipse coefficient α2 / α1 in this modification is 1. α1 corresponds to the dimension of one of the major and minor axes of the ellipse along the axis direction that passes through the intersection region J. α2 corresponds to the dimension of one of the major and minor axes of the ellipse along the axis direction that does not pass through the intersection region J.

[0153] The first envelope E1A is linear and inclined with respect to the propagation axis. Similarly, the second envelope E2A is linear and inclined with respect to the propagation axis. The intersection region J of the IDT electrode 18B has a shape that is line-symmetric with respect to an axis extending parallel to the propagation axis. However, the first envelope E1A and the second envelope E2A may extend in parallel. In this modification, the first bus bar 14A and the second bus bar 15A have a linear shape.

[0154] When a straight line passing through the center of the intersection region J is taken as a reference line, in this modified example, the two-dot chain line N1 coincides with the reference line. Note that the reference line does not necessarily need to extend parallel to the direction in which the propagation axis extends. As described above, the centers of the circles including the arcs in the shapes of the multiple electrode fingers coincide. This center is taken as a fixed point. The angle between the reference line and the straight line passing through the first envelope E1A and the fixed point is taken as the intersection angle θ. C1_APHowever, in this modification, the extension of the first envelope E1A passes through a fixed point. Therefore, the intersection angle θ C1_AP is synonymous with the angle formed by an extension of the first envelope E1A and the reference line.

[0155] The angle between the second envelope E2 and the line passing through the fixed point and the reference line is called the intersection angle θ C2_AP However, in this modification, the extension of the second envelope E2A passes through a fixed point. Therefore, the intersection angle θ C2_AP is synonymous with the angle between the extension line of the second envelope E2A and the reference line. C_prop In this case, θ C_AP2 ≦θ C_prop ≦θ C_AP1 In this modified example, the intersection angle θ C_AP1 and intersection angle θ C_AP2 The absolute value of is the same. Therefore, the excitation angle θ C_prop The absolute value of is 0°≦|θ C_prop |≦|θ C_AP1 |=|θ C_AP2 |is.

[0156] The shape of the first offset electrodes 12B and the second offset electrodes 13B in plan view is an arc shape. Specifically, the shape of the first offset electrodes 12B and the second offset electrodes 13B in plan view is a shape that corresponds to each of the arcs of the concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the offset electrodes coincide with each other. More specifically, in this modification, the centers of the circles including the arcs in the shapes of the electrode fingers and the offset electrodes coincide with each other. This makes it possible to effectively suppress leakage from the crossing region J of the main mode.

[0157] However, the shape of the offset electrodes is not limited to the above. For example, the shape of the offset electrodes in a plan view may be linear. In this case, the length of the offset electrodes can be shortened. This can reduce the electrical resistance of the IDT electrode 18B.

[0158] The shape of the reflector electrode fingers of reflector 9E and reflector 9F in a plan view corresponds to each of the arcs of the concentric circles. More specifically, in this modification, the centers of the circles including the arcs in the shapes of the electrode fingers and the reflector electrode fingers are aligned. This makes it possible to more reliably improve the resonance characteristics. However, the shape of the reflector electrode fingers is not limited to the above.

[0159] The shape of the electrode fingers in plan view may include an elliptical arc shape. More specifically, in this case, the shape of the electrode fingers in plan view includes shapes corresponding to the elliptical arcs of a plurality of ellipses having the same center of gravity. The center of gravity here refers to the center of the two focal points of the ellipse. In this case, the excitation angle variable resonator can also suppress unnecessary out-of-band waves such as Rayleigh waves, as in the fifth modification. When the shape of the electrode fingers including the arc is an ellipse, the elliptical coefficient α2 / α1 is other than 1.

[0160] When the shape of the electrode fingers in a plan view includes an elliptical arc, it is preferable that the shape of the offset electrodes in a plan view also includes an elliptical arc. In this case, it is preferable that the centers of gravity of the ellipses including the elliptical arcs in the shapes of the electrode fingers and the offset electrodes coincide with each other. This makes it possible to effectively suppress leakage from the crossing region J of the main mode.

[0161] When the shape of the plurality of electrode fingers in a plan view includes an elliptical arc, it is preferable that the shape of the plurality of reflector electrode fingers of each reflector in a plan view also includes an elliptical arc. In this case, it is preferable that the center of gravity of the ellipse including the elliptical arc in the shape of the plurality of electrode fingers and the shape of the plurality of reflector electrode fingers coincides. This makes it possible to more reliably improve the resonance characteristics.

[0162] FIG. 14 is a schematic plan view of an excitation angle variable resonator of a first filter in a sixth modified example of the first embodiment.

[0163] In IDT electrode 18C of this modification, first electrode fingers 16C and second electrode fingers 17C have a shape in plan view that is bent at multiple nodes. More specifically, first electrode fingers 16C and second electrode fingers 17C have a shape in plan view that is formed by connecting straight lines at each node. In this modification, each electrode finger is bent as a whole so as to be convex toward the right in FIG. 14. The shape of each electrode finger in plan view can be approximated to a circular arc, an elliptical arc, or a parabola.

[0164] Fig. 15 is a schematic plan view showing parallel regions and non-parallel regions in a sixth modified example of the first embodiment. In Fig. 15, each region is shown with hatching. Note that parallel regions and regions extending from parallel regions, which will be described later, are shown with the same hatching. Non-parallel regions and regions extending from non-parallel regions, which will be described later, are shown with the same hatching.

[0165] The intersection region J has a plurality of parallel regions A and a plurality of non-parallel regions B. Specifically, the parallel region A is a region in which the plurality of first electrode fingers 16C and the plurality of second electrode fingers 17C extend in parallel. The non-parallel region B is a region in which the extension directions of the plurality of first electrode fingers 16C and the plurality of second electrode fingers 17C intersect with each other. Note that it is sufficient that the intersection region J includes at least two parallel regions A and at least one non-parallel region B.

[0166] In the IDT electrode 18C, all of the parallel regions A and all of the non-parallel regions B each include a portion of all of the first electrode fingers 16C and a portion of all of the second electrode fingers 17C. However, the parallel regions A do not necessarily have to include a portion of all of the first electrode fingers 16C and a portion of all of the second electrode fingers 17C. The same applies to the non-parallel regions B.

[0167] The parallel regions A and the non-parallel regions B are arranged alternately. The first electrode fingers 16C and the second electrode fingers 17C each extend linearly in the parallel regions A and the non-parallel regions B, and are bent at the boundaries between the parallel regions A and the non-parallel regions B. In this embodiment, the parallel regions A and the non-parallel regions B are arranged alternately in the entire intersection region J. It is sufficient that the parallel regions A and the non-parallel regions B are arranged alternately in at least a part of the intersection region J.

[0168] In the parallel regions A, the directions in which the electrode fingers extend are different from each other. Therefore, in the intersection region J, the excitation direction and excitation angle θ C_prop However, this is not uniform.

[0169] The reflector electrode fingers of reflector 9G and reflector 9H have a shape in plan view that is bent at multiple nodes, similar to each electrode finger of IDT electrode 18C. Specifically, the reflector electrode fingers extend linearly in a region extending from parallel region A and a region extending from non-parallel region B. The reflector electrode fingers are bent at the boundary between the region extending from parallel region A and the region extending from non-parallel region B. This makes it possible to more reliably improve the resonance characteristics.

[0170] In this modification, the first offset electrodes 12C and the second offset electrodes 13C have a linear shape in plan view. The first offset electrodes 12C and the second offset electrodes 13C may have a curved shape in plan view in which straight lines are connected to each other.

[0171] FIG. 16 is a schematic plan view of an excitation angle variable resonator of a first filter in a seventh modified example of the first embodiment.

[0172] In this modification, the electrode fingers of IDT electrode 18D include linear portions. Specifically, the intersection region of IDT electrode 18D has a first region W1, a second region W2, and a third region W3. First region W1, second region W2, and third region W3 are arranged in a direction in which first bus bar 14A and second bus bar 15A face each other. More specifically, first region W1 and second region W2 face each other with third region W3 in between. First region W1 is located on the first bus bar 14A side. Second region W2 is located on the second bus bar 15A side. In third region W3, the shape of the electrode fingers in a plan view is linear.

[0173] On the other hand, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view is an elliptical arc shape. In this way, each electrode finger includes a portion whose shape in a plan view has a different curvature. Note that, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view may be a circular arc shape. Alternatively, in the first region W1 and the second region W2, the shape of the multiple electrode fingers in a plan view may be a curved shape that can be approximated to a circular arc or an elliptical arc. In this modification, too, in the intersection region, the excitation direction and excitation angle θ of the acoustic wave are C_prop However, this is not uniform.

[0174] In this modification, in the entire third region W3, the direction in which the propagation axis of the piezoelectric layer 6 extends is perpendicular to the direction in which the electrode fingers extend. C_prop is 0°. Therefore, the third region W3 is a stable region with respect to the propagation axis. By including the third region W3 in the crossing region, it is possible to suppress deterioration of the fractional bandwidth. The fractional bandwidth is expressed by |fr-fa| / fr×100[%], where fr is the resonant frequency and fa is the anti-resonant frequency. Note that the excitation angle θ in the third region W3 is C_prop is not limited to 0°.

[0175] FIG. 17 is a schematic plan view of an excitation angle variable resonator of a first filter according to an eighth modified example of the first embodiment.

[0176] In this modified example, the intersection region has a plurality of curved regions. Specifically, the plurality of curved regions are a first curved region K1 and a second curved region K2. The first curved region K1 includes a first envelope E1A. The second curved region K2 includes a second envelope E2A. The boundary between the first curved region K1 and the second curved region K2 is linear.

[0177] In this modification, in each curved region, the shape of the first electrode fingers 16E and the second electrode fingers 17E in plan view is a single arc shape. Each of the electrode fingers in plan view is a shape in which two arcs are connected. In each electrode finger, the two curved shapes are inverted from each other at the boundary between the first curved region K1 and the second curved region K2.

[0178] Specifically, in the first curved region K1, the electrode fingers are curved so as to convex toward the right in FIG. 17. The arcs in the shapes of the portions of the electrode fingers located in the first curved region K1 correspond to the arcs in the multiple concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the electrode fingers in the first curved region K1 are aligned.

[0179] On the other hand, in the second curved region K2, the multiple electrode fingers are curved so as to convex leftward in Fig. 17. The arcs in the shapes of the multiple electrode fingers located in the second curved region K2 are the respective arcs of multiple concentric circles. Therefore, the centers of the circles including the arcs in the shapes of the multiple electrode fingers in the second curved region K2 are aligned.

[0180] The center of a circle including arcs in the shape of the multiple electrode fingers in the first curved region K1 and the center of a circle including arcs in the shape of the multiple electrode fingers in the second curved region K2 face each other across the IDT electrode 18E.

[0181] In this way, the shapes of the first electrode fingers 16E and the second electrode fingers 17E in a plan view may each include at least two curved portions in which the first electrode fingers 16E and the second electrode fingers 17E bend in different directions in the crossing region. In this case, in the crossing region, the excitation direction and excitation angle θ of the acoustic wave C_prop However, this is not uniform.

[0182] In each curved region, the shape of the electrode fingers in plan view may be a single elliptical arc, or, for example, in each curved region, the shape of the electrode fingers in plan view may be a curved shape that can be approximated to a single circular or elliptical arc.

[0183] Like the electrode fingers of the IDT electrode 18E, the reflector electrode fingers of each reflector have a shape in plan view that is formed by connecting two circular arcs. The reflector electrode fingers may have a shape in plan view that is formed by connecting two elliptical arcs. Alternatively, for example, the reflector electrode fingers may have a shape in plan view that is formed by connecting two curved lines that can be approximated to a circular arc or an elliptical arc.

[0184] FIG. 18 is a schematic plan view of an excitation angle variable resonator of a first filter in a ninth modification of the first embodiment.

[0185] The intersection region J of the IDT electrode 18F has a central region F and a pair of edge regions. Specifically, the pair of edge regions are a first edge region H1 and a second edge region H2. The first edge region H1 includes a first envelope E1A as an edge portion. The second edge region H2 includes a second envelope E2A as an edge portion. The first edge region H1 and the second edge region H2 face each other with the central region F in between. It should be noted that each intersection region in other embodiments and modified examples also has a first edge region, a second edge region, and a central region.

[0186] First edge region H1 is defined as a region where the tip of second electrode finger 17F and the adjacent portion of first electrode finger 16F are located. That is, first edge region H1 is defined as a region in a range of about 1λ from the tip of second electrode finger 17F along the direction in which the electrode fingers extend, based on second electrode finger 17F. Similarly, second edge region H2 is defined as a region in a range of about 1λ from the tip of first electrode finger 16F along the direction in which the electrode fingers extend, based on the first electrode finger.

[0187] Each electrode finger of the IDT electrode 18F has a wide portion in the first edge region H1 and the second edge region H2. The width of the electrode finger in the wide portion is wider than the width of the electrode finger in the central region F.

[0188] Specifically, the first electrode finger 16F has a wide portion 16a in the first edge region H1. The second electrode finger 17F also has a wide portion 17a in the first edge region H1. Meanwhile, the first electrode finger 16F has a wide portion 16b in the second edge region H2. The second electrode finger 17F also has a wide portion 17b in the second edge region H2. As a result, the sound velocity in the first edge region H1 and the second edge region H2 is lower than the sound velocity in the central region F. As a result, a low sound velocity region is formed in the first edge region H1 and the second edge region H2. The low sound velocity region is a region in which the sound velocity is lower than the sound velocity in the central region F. Note that the low sound velocity region may be formed in at least a part of at least one of the first edge region H1 and the second edge region H2. However, as in this modified example, it is preferable that the low acoustic velocity region is formed in the entirety of both the first edge region H1 and the second edge region H2.

[0189] In this modification, the central region F and a pair of low sound velocity regions are arranged in this order from the inside to the outside in the direction in which the first busbar 14A and the second busbar 15A face each other. This establishes a piston mode. This makes it possible to suppress the transverse mode. In addition, the energy of the main mode can be effectively confined to the center side of the intersection region J, making it possible to improve the characteristics of the main mode.

[0190] The configuration of the IDT electrode 18F is the same as that of the fifth modification, except for the first edge region H1 and the second edge region H2. C_prop However, this is not uniform.

[0191] In at least one of the first edge region H1 and the second edge region H2, at least one electrode finger may have a wide portion. However, in at least one of the first edge region H1 and the second edge region H2, it is preferable that a plurality of electrode fingers have a wide portion, and it is more preferable that all electrode fingers have a wide portion. In both the first edge region H1 and the second edge region H2, it is more preferable that a plurality of electrode fingers have a wide portion, and it is even more preferable that all electrode fingers have a wide portion. This makes it possible to more reliably establish the piston mode.

[0192] The electrode fingers of the IDT electrode 18F have an arc shape in a plan view. However, the configuration in which a low acoustic velocity region is provided in the first edge region H1 or the second edge region H2 of the acoustic wave resonator may also be adopted in other configurations of the present invention in which the electrode fingers have a different shape from that of this modified example.

[0193] In the IDT electrode 18F, the width of each electrode finger is wider over the entire edge region. The shape of each wide portion in plan view is rectangular. However, each electrode finger may be wider in at least a part of each edge region. The shape of each wide portion in plan view is not limited to a rectangular shape. Each reflector electrode finger of each reflector may also be wider in a portion located on an extension of the first edge region H1 and a portion located on an extension of the second edge region H2.

[0194] 19, a plurality of mass-adding films 19 are provided, thereby forming low acoustic velocity regions in the first edge region H1 and the second edge region H2. Specifically, in the first edge region H1, mass-adding films 19 are provided on each of the first electrode fingers 16B and each of the second electrode fingers 17B. The same is true in the second edge region H2. The configuration of the IDT electrode 18B is the same as that of the fifth modification.

[0195] In this modification, each mass-adding film 19 is provided only on one electrode finger. In this case, the material of the mass-adding film 19 can be an appropriate metal or dielectric. However, the mass-adding film 19 may be provided over a plurality of electrode fingers. In this case, the material of the mass-adding film 19 can be an appropriate dielectric.

[0196] The mass adding film 19 may be laminated with at least one of the plurality of electrode fingers in at least one of the first edge region H1 and the second edge region H2. Specifically, the mass adding film 19 may be provided so as to overlap at least one of the plurality of first electrode fingers 16B and the plurality of second electrode fingers 17B in at least one of the first edge region H1 and the second edge region H2 in a plan view. In this case, a low acoustic velocity region is formed in at least a part of at least one of the first edge region H1 and the second edge region H2.

[0197] In at least one of the first edge region H1 and the second edge region H2, it is preferable that a plurality of electrode fingers are laminated with the mass addition film 19, and it is more preferable that all of the electrode fingers are laminated with the mass addition film 19. Alternatively, it is more preferable that a plurality of electrode fingers are laminated with the mass addition film 19 in both the first edge region H1 and the second edge region H2. This makes it possible to more reliably establish the piston mode. It is even more preferable that all of the electrode fingers are laminated with the mass addition film 19 in both edge regions. In this case, the low sound velocity region is formed in the entirety of both edge regions. This makes it possible to more reliably establish the piston mode.

[0198] In the portion where the electrode fingers and the mass addition film 19 are laminated, the piezoelectric substrate 2, the electrode fingers, and the mass addition film 19 are laminated in this order. However, in the portion where the electrode fingers and the mass addition film 19 are laminated, the piezoelectric substrate 2, the mass addition film 19, and the electrode fingers may also be laminated in this order. That is, the mass addition film 19 may be provided between the piezoelectric substrate 2 and the electrode fingers. The portion of each reflector electrode finger of each reflector located on the extension of the first edge region H1 and the portion located on the extension of the second edge region H2 may also be laminated with the mass addition film 19.

[0199] The mass-adding film 19 may be made of the same metal as that used for each electrode finger. This configuration corresponds to the configuration of the eleventh modified example shown in FIG. 20(a) and FIG. 20(b). That is, as shown in FIG. 20(a), in the IDT electrode 18G, the thickness of the first electrode finger 16G in the first edge region H1 and the second edge region H2 is thicker than the thickness of the first electrode finger 16G in the central region F. As shown in FIG. 20(b), the thickness of the second electrode finger 17G in the first edge region H1 and the second edge region H2 is thicker than the thickness of the second electrode finger 17G in the central region F. As a result, low acoustic velocity regions are formed in the first edge region H1 and the second edge region H2, respectively.

[0200] 20(a) shows a schematic cross section of first electrode finger 16G along the extension direction of first electrode finger 16G. Similarly, FIG. 20(b) shows a schematic cross section of second electrode finger 17G along the extension direction of second electrode finger 17G. The configuration of IDT electrode 18G is similar to that of the fifth modified example, except for first edge region H1 and second edge region H2.

[0201] It is sufficient that the thickness of at least one electrode finger in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F. However, it is preferable that the thickness of each of the multiple electrode fingers in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F. It is more preferable that the thickness of each of the electrode fingers in at least one of the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode finger in the central region F.

[0202] It is more preferable that the thickness of each of the plurality of electrode fingers in both the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode fingers in the central region F. It is even more preferable that the thickness of each of the electrode fingers in both the first edge region H1 and the second edge region H2 is greater than the thickness of the electrode fingers in the central region F. This makes it possible to more reliably establish the piston mode.

[0203] In this modification, the thickness of each electrode finger is thick over the entire edge region. However, the thickness of each electrode finger may be thicker in at least a part of each edge region. Each reflector electrode finger of each reflector may also be thicker in a portion located on an extension of the first edge region H1 and a portion located on an extension of the second edge region H2. Note that a low acoustic velocity region may be formed by applying multiple configurations among the ninth to eleventh modifications.

[0204] FIG. 21 is a schematic plan view of an excitation angle variable resonator of a first filter in a twelfth modified example of the first embodiment.

[0205] The configuration of the IDT electrode 18H in this modification is the same as the configuration of the IDT electrode 18F in the ninth modification, except for the first offset electrode 12H and the second offset electrode 13H. Therefore, in the crossing region J, the excitation direction and excitation angle θ C_prop However, the width of the tip of the first offset electrode 12H of this modification is wider than the width of the other parts of the first offset electrode 12H. The width of the tip of the second offset electrode 13H is wider than the width of the other parts of the second offset electrode 13H.

[0206] Fig. 22 is a schematic circuit diagram of a multiplexer according to a second embodiment of the present invention, and Fig. 23 is a schematic plan view of a first filter in the second embodiment.

[0207] 22 and 23, this embodiment differs from the first embodiment in that the parallel arm resonators of the parallel arm resonator section P21 are variable excitation angle resonators. Except for the above, the multiplexer of this embodiment has the same configuration as the multiplexer 1 of the first embodiment. Note that the circuit configuration of the second embodiment is the same as that of the first embodiment.

[0208] The first filter 21A in the second embodiment and the first filter in the first comparative example were compared in terms of attenuation-frequency characteristics near a frequency at which Rayleigh waves are generated as unwanted waves outside the band. The first comparative example is similar to the comparative example for comparison shown in FIG. 9. The attenuation-frequency characteristics in the first embodiment are also shown. The design parameters of the parallel arm resonators in the parallel arm resonator section P21 are shown below. The design parameters of each series arm resonator in the series arm resonator section S1 were similar to the design parameters in the first embodiment for comparison shown in FIG. 9.

[0209] The thickness of each member in the parallel arm resonator is the same as the thickness of each member in the series arm resonator. However, the wavelength λ in the parallel arm resonator is different from the wavelength λ in the series arm resonator. Therefore, the thickness value of each member in the parallel arm resonator based on the wavelength λ is different from the thickness value of each member in the series arm resonator based on the wavelength λ.

[0210] Support substrate: Material: Si, surface orientation: (100), Euler angles (φ, θ, ψ) are 45° First intermediate layer: Material: SiN, thickness: 0.491λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.367λ Piezoelectric layer: Material: Rotated Y-cut 50°X-propagation LiTaO3, thickness: 0.327λ IDT electrode: Material: Al, thickness: 0.0791λ Dielectric film: Material: SiO2, thickness: 0.0191λ Wavelength λ: Excitation angle θ C_prop 1.8325μm at 0°

[0211] Fig. 24 is a diagram showing the attenuation-frequency characteristics of the first filter in the second embodiment and the first comparative example near the frequency at which Rayleigh waves are generated. Fig. 25 is a diagram showing the attenuation-frequency characteristics of the first filter in the first embodiment and the first comparative example near the frequency at which Rayleigh waves are generated.

[0212] 24, in the first comparative example, Rayleigh waves are generated near the frequencies indicated by the arrows T5 and T6. Rayleigh waves are unwanted waves outside the band. In contrast, in the second embodiment, it can be seen that the Rayleigh waves are suppressed.

[0213] On the other hand, as shown in Fig. 25, in the first embodiment, the Rayleigh waves are not suppressed. In the first embodiment shown in Fig. 1, unlike the second embodiment, the parallel arm resonator of the parallel arm resonator section P1 in the first filter 1A is not an excitation angle variable resonator. Therefore, it can be seen that the Rayleigh waves are generated in the parallel arm resonator of the parallel arm resonator section P1. And, in the second embodiment, it can be seen that the Rayleigh waves, which are unnecessary waves outside the band, are suppressed because the parallel arm resonator is an excitation angle variable resonator.

[0214] In the first filter of the first embodiment, the second embodiment, and the first comparative example, the return loss on the common connection terminal side was measured.

[0215] FIG. 26 is a diagram showing return losses in the first embodiment, the second embodiment, and the first comparative example.

[0216] As shown in FIG. 26, in the first and second embodiments, the unwanted waves around 1725 MHz can be suppressed more effectively than in the first comparative example. These unwanted waves are generated in the series arm resonators. Furthermore, it can be seen that the second embodiment can also suppress the unwanted waves around 1650 MHz. These unwanted waves are generated in the parallel arm resonators. Therefore, in the second embodiment, both the unwanted waves outside the band caused by the series arm resonators and the unwanted waves outside the band caused by the parallel arm resonators can be effectively suppressed. This makes it possible to effectively suppress the influence of the unwanted waves on the filters other than the first filter 21A in the multiplexer.

[0217] In the second embodiment, the parallel arm resonator section P21 includes only one parallel arm resonator, but the parallel arm resonator section P21 may include multiple parallel arm resonators. In this case, it is preferable that at least one parallel arm resonator of the parallel arm resonator section P21 located closest to the first signal terminal 3A among the multiple parallel arm resonator sections is a variable excitation angle resonator. It is more preferable that half or more of the parallel arm resonators of the parallel arm resonator section P21 are variable excitation angle resonators, and it is even more preferable that all of the parallel arm resonators of the parallel arm resonator section P21 are variable excitation angle resonators. This makes it possible to effectively suppress the influence of unwanted waves on other filters.

[0218] It is preferable that at least one resonator in at least one of the series arm resonator section S1 located closest to the first signal terminal 3A and the parallel arm resonator section P21 located closest to the first signal terminal 3A is a variable excitation angle resonator. When both the series arm resonator section S1 and the parallel arm resonator section P21 include multiple resonators, it is more preferable that more than half of the resonators in both the series arm resonator section S1 and the parallel arm resonator section P21 are variable excitation angle resonators. It is even more preferable that all of the resonators in both of the above sections are variable excitation angle resonators. This makes it possible to more reliably and effectively suppress the influence of unwanted waves on other filters.

[0219] FIG. 27 is a schematic circuit diagram of a multiplexer according to the third embodiment.

[0220] This embodiment differs from the second embodiment in the circuit configuration of the first filter 31A and the arrangement of the excitation angle variable resonators. Except for the above points, the multiplexer of this embodiment has the same configuration as the multiplexer of the second embodiment.

[0221] The plurality of series arm resonator sections of the first filter 31A are the series arm resonator section S31, the series arm resonator section S32, the series arm resonator section S33, and the series arm resonator section S34. In this embodiment, the series arm resonator section S31 includes a series arm resonator S31a and a series arm resonator S31b. The series arm resonator S31a and the series arm resonator S31b are connected in series with each other. The series arm resonator section S32 includes a series arm resonator S32a, a series arm resonator S32b, and a series arm resonator S32c. The series arm resonator S32a, the series arm resonator S32b, and the series arm resonator S32c are connected in series with each other in this order. On the other hand, each of the series arm resonator sections S33 and S34 is composed of one series arm resonator.

[0222] From the first signal terminal 3A side, the series arm resonator section S31, the series arm resonator section S32, the series arm resonator section S33 and the series arm resonator section S34 are connected in series to one another in this order.

[0223] The multiple parallel arm resonator sections of the first filter 31A are the parallel arm resonator section P31, the parallel arm resonator section P32, the parallel arm resonator section P33, and the parallel arm resonator section P34. The parallel arm resonator section P31 includes a parallel arm resonator P31a and a parallel arm resonator P31b. The parallel arm resonator P31a and the parallel arm resonator P31b are connected in series to each other. In this embodiment, the parallel arm resonator P31a and the parallel arm resonator P31b are resonators divided in series. On the other hand, the parallel arm resonator section P32, the parallel arm resonator section P33, and the parallel arm resonator section P34 are each formed of one parallel arm resonator.

[0224] In addition, when the parallel arm resonator section includes multiple parallel arm resonators, the multiple parallel arm resonators do not need to be parallel arm resonators divided in series. There is no particular limitation on the relationship between the design parameters of the multiple parallel arm resonators in the parallel arm resonator section. The multiple parallel arm resonators in the parallel arm resonator section may be connected in series to each other or in parallel to each other. Alternatively, the multiple parallel arm resonators in the parallel arm resonator section may be located in different parallel arms that are located in the same section.

[0225] The parallel arm resonator section P31 is connected between a node D between the first signal terminal 3A and the series arm resonator section S31 and the ground potential. The parallel arm resonator section P32 is connected between a node D between the series arm resonator section S31 and the series arm resonator section S32 and the ground potential. The parallel arm resonator section P33 is connected between a node D between the series arm resonator section S32 and the series arm resonator section S33 and the ground potential. The parallel arm resonator section P34 is connected between a node D between the series arm resonator section S33 and the series arm resonator section S34 and the ground potential. In this embodiment, the resonator sections located closest to the first signal terminal 3A among the multiple resonators are the series arm resonator section S31 and the parallel arm resonator section P31.

[0226] In the first filter 31A of this preferred embodiment, all the series arm resonators in the series arm resonator section S31 and all the parallel arm resonators in the parallel arm resonator section P31 are variable excitation angle resonators. On the other hand, all the other elastic wave resonators are not variable excitation angle resonators. Specifically, each elastic wave resonator that is not a variable excitation angle resonator is configured similarly to the elastic wave resonator shown in FIG. 7. That is, the IDT electrodes of each of the elastic wave resonators are inclined IDT electrodes.

[0227] For example, only the parallel arm resonator of the parallel arm resonator section P31 may be an excitation angle variable resonator. In the modification of the third embodiment shown in Fig. 28, in the first filter, all the parallel arm resonators of the parallel arm resonator section P31 are excitation angle variable resonators. On the other hand, all the elastic wave resonators other than the parallel arm resonator of the parallel arm resonator section P31 are configured similarly to the elastic wave resonator shown in Fig. 7.

[0228] The return loss on the common connection terminal side of the first filter was compared between the third embodiment, its modified example, and the second comparative example. The second comparative example differs from the third embodiment in that all the acoustic wave resonators are configured similarly to the acoustic wave resonators shown in Fig. 7. The circuit configuration of the multiplexer in the second comparative example is similar to that of the third embodiment.

[0229] FIG. 29 is a diagram showing return losses in the third embodiment, its modification, and the second comparative example.

[0230] 29, the unwanted waves occurring near 1725 MHz are unwanted waves occurring in the series arm resonators. The unwanted waves occurring near 1650 MHz are unwanted waves occurring in the parallel arm resonators. It can be seen that in the third embodiment and its modifications, the unwanted waves caused by the parallel arm resonators are more effectively suppressed than in the second comparative example. This is because, in the third embodiment and its modifications, each parallel arm resonator in the parallel arm resonator section P31 is an excitation angle variable resonator.

[0231] In the modified example of the third embodiment, the unwanted waves around 1725 MHz are generated to the same extent as in the second comparative example. On the other hand, in the third embodiment, the unwanted waves around 1725 MHz can be suppressed. This is because, in the third embodiment, each series arm resonator of the series arm resonator section S31 is an excitation angle variable resonator.

[0232] In the third embodiment, both of the out-of-band spurious waves caused by the series arm resonators and the out-of-band spurious waves caused by the parallel arm resonators can be effectively suppressed, thereby effectively suppressing the influence of the spurious waves on the filters other than the first filter 31A in the multiplexer.

[0233] FIG. 30 is a schematic circuit diagram of a multiplexer according to the fourth embodiment.

[0234] This embodiment differs from the first embodiment in that all the first half resonators are variable excitation angle resonators. Except for the above, the multiplexer of this embodiment has the same configuration as the multiplexer of the second embodiment.

[0235] As described above, when an unwanted wave outside the band occurs in the first half resonator, the unwanted wave has a particularly large effect on other filters. In this embodiment, all the first half resonators are variable excitation angle resonators. Therefore, the unwanted wave outside the band can be suppressed in all the first half resonators. This makes it possible to suppress the effect of the unwanted wave, such as a Rayleigh wave, on filters in the multiplexer other than the first filter 41A.

[0236] FIG. 31 is a schematic circuit diagram of a multiplexer according to the fifth embodiment.

[0237] This embodiment differs from the second embodiment in the circuit configuration of the first filter 51A and the arrangement of the excitation angle variable resonators. This embodiment also differs from the second embodiment in that the first filter 51A includes a longitudinally coupled resonator type acoustic wave filter 55. Other than the above, the multiplexer of this embodiment has the same configuration as the multiplexer of the second embodiment.

[0238] The longitudinally coupled resonator elastic wave filter 55 of the first filter 51A has a single stage of a 5-IDT type. However, the number of IDT electrodes of the longitudinally coupled resonator elastic wave filter 55 is not limited to five. The longitudinally coupled resonator elastic wave filter 55 may be, for example, a 3-IDT type, a 7-IDT type, or a 9-IDT type. The longitudinally coupled resonator elastic wave filter 55 may have two or more stages.

[0239] In this specification, in a ladder section constituting a filter, a vertically coupled resonator type elastic wave filter is treated as a series arm resonator section. Even when a vertically coupled resonator type elastic wave filter is configured with two or more stages, the vertically coupled resonator type elastic wave filter is treated as one series arm resonator section in the ladder section.

[0240] The longitudinally coupled resonator type acoustic wave filter 55 is provided between the first signal terminal 3A and the second signal terminal 3B.

[0241] The multiple series arm resonator sections of the first filter 51A are series arm resonator section S51, series arm resonator section S52, and series arm resonator section S53. In this embodiment, the series arm resonator section S51 includes a series arm resonator S51a and a series arm resonator S51b. The series arm resonator S51a and the series arm resonator S51b are connected in series with each other. The series arm resonator section S53 includes a series arm resonator S53a and a series arm resonator S53b. The series arm resonator S53a and the series arm resonator S53b are connected in parallel with each other. On the other hand, the series arm resonator section S52 is composed of one series arm resonator.

[0242] The series arm resonator section S51 and the series arm resonator section S52 are connected between the first signal terminal 3A and the longitudinally coupled resonator type acoustic wave filter 55. Of the series arm resonator section S51 and the series arm resonator section S52, the series arm resonator section S51 is located on the first signal terminal 3A side. The series arm resonator section S53 is connected between the longitudinally coupled resonator type acoustic wave filter 55 and the second signal terminal 3B.

[0243] The multiple parallel arm resonator sections of the first filter 51A are a parallel arm resonator section P51 and a parallel arm resonator section P52. The parallel arm resonator section P51 includes a parallel arm resonator P51a and a parallel arm resonator P51b. The parallel arm resonators P51a and P51b are connected in series with each other. On the other hand, the parallel arm resonator section P52 is composed of one parallel arm resonator.

[0244] The parallel arm resonator section P51 is connected between a node D between the series arm resonator section S51 and the series arm resonator section S52 and ground potential. The parallel arm resonator section P52 is connected between a node D between the longitudinally coupled resonator type acoustic wave filter 55 and the series arm resonator section S53 and ground potential. In this embodiment, the resonator section located closest to the first signal terminal 3A among the multiple resonator sections is the series arm resonator section S51.

[0245] Fig. 32 is a circuit diagram for explaining the ladder section of the first filter in the fifth embodiment. In Fig. 32, for the sake of convenience in explaining the ladder section, one parallel arm and a parallel arm resonator section located in the parallel arm are indicated by the symbols of two parallel arms and two resonators.

[0246] In the first filter 51A, a four-stage ladder section is configured between the first signal terminal 3A and the second signal terminal 3B. The first to fourth ladder sections are arranged in order from the first signal terminal 3A side to the second signal terminal 3B side. The third ladder section is a ladder section in which the longitudinally coupled resonator type elastic wave filter 55 is treated as one series arm resonator section.

[0247] In this embodiment, the first and second ladder sections are the first half of the ladder section. The first half of the resonators are the series arm resonators S51a, S51b, P51a, P51b, and S52 shown in FIG. 31. All of these first half of the resonators are variable excitation angle resonators. Therefore, it is possible to suppress unwanted waves outside the band in all of the first half of the resonators. Therefore, it is possible to effectively suppress the influence of unwanted waves on filters other than the first filter 51A in the multiplexer.

[0248] In the first to fifth embodiments, when the resonator section includes a plurality of resonators, and all of the resonators are excitation angle variable resonators, the resonators are configured in the same manner. However, the configurations of the excitation angle variable resonators included in the same resonator section may be different from each other. This example is shown in the sixth embodiment. The circuit configuration in the sixth embodiment is similar to that in the first embodiment. Therefore, the drawings and symbols used in the description of the first embodiment may be used in the description of the sixth embodiment.

[0249] Fig. 33 is a schematic plan view of a plurality of excitation angle variable resonators of the first filter in the sixth embodiment. Fig. 33 shows a plurality of series arm resonators in a series arm resonator section S61 that is located closest to the first signal terminal 3A among the plurality of series arm resonator sections.

[0250] This embodiment differs from the first embodiment in that the configurations of the three series arm resonators in the series arm resonator section S61 are different from each other. In all other respects, the multiplexer of this embodiment has the same configuration as the multiplexer 1 of the first embodiment.

[0251] The series arm resonator section S61 includes a series arm resonator S61a, a series arm resonator S61b, and a series arm resonator S61c, which are connected in series to one another in this order.

[0252] The series arm resonator S61a, the series arm resonator S61b, and the series arm resonator S61c are connected to each other by wiring electrodes. In FIG. 33, solid line boundaries are drawn between the bus bars and the wiring electrodes. Thus, in FIG. 33, the bus bars and the wiring electrodes are shown as being separated from each other. In this embodiment, the bus bars and the wiring electrodes are integrally formed from the same material. However, the bus bars and the wiring electrodes may be formed from different materials. Alternatively, the layered configurations of the bus bars and the wiring electrodes may be different from each other.

[0253] The series arm resonator S61a and the series arm resonator S61b are configured in the same manner as the variable excitation angle resonator in the first preferred embodiment shown in Fig. 5. However, the series arm resonator S61a and the series arm resonator S61b have different duty ratios. In addition, the series arm resonator S61a and the series arm resonator S61b are arranged at positions different from each other by 180°. Specifically, the multiple electrode fingers of the series arm resonator S61a are curved so as to be convex in the right direction in Fig. 33. The multiple electrode fingers of the series arm resonator S61b are curved so as to be convex in the left direction in Fig. 33.

[0254] The series arm resonator S61c is configured similarly to the variable excitation angle resonator in the fifth modified example of the first embodiment shown in Fig. 13. The two-dot chain line N1 in Fig. 33 coincides with the reference line. The angle between the extension line of the first envelope curve E1A and the reference line is the intersection angle θ C_AP1 The angle between the extension line of the second envelope E2A and the reference line is the intersection angle θ C_AP2 It is.

[0255] In the series arm resonator S61c, the excitation angle θ is set so that the resonant frequency or the anti-resonant frequency is approximately the same in the entire crossing region. C_prop The duty ratio changes according to the change in the duty ratio of the series arm resonator S61c. The plurality of electrode fingers in the series arm resonator S61c are curved so as to protrude rightward in FIG.

[0256] In the first filter of this embodiment, unwanted waves outside the band can be effectively suppressed. This is because each series arm resonator in the series arm resonator section S61 is an excitation angle variable resonator, and the frequencies of unwanted waves generated in each series arm resonator can be dispersed. This will be described below. The design parameters of the series arm resonator S61a are as follows. Note that these design parameters are the same as the design parameters of the excitation angle variable resonator in the first embodiment for comparison shown in FIG. 9.

[0257] Support substrate: Material: Si, surface orientation: (100), Euler angles (φ, θ, ψ) are 45° First intermediate layer: Material: SiN, thickness: 0.514λ Second layer of the intermediate layer: Material: SiO2, thickness: 0.384λ Piezoelectric layer: Material: Rotated Y-cut 50°X-propagation LiTaO3, thickness: 0.343λ IDT electrode: Material: Al, thickness: 0.05λ Dielectric film: Material: SiO2, thickness: 0.02λ Wavelength λ: Excitation angle θ C_prop 1.7509μm at 0° Number of pairs of IDT electrode fingers: 100 pairs Duty ratio: 0.5 Gap length: 0.135λ Offset electrode length: 3.5λ Distance between the first envelope and the second envelope in a direction perpendicular to the propagation axis: 25 λ First envelope: Absolute value of the inclination angle with respect to the propagation axis... 20°, number of pairs of electrode fingers between the bends V1... 20 pairs Second envelope: absolute value of inclination angle with respect to the propagation axis: 20°, number of pairs of electrode fingers between bends V2: 20 pairs First envelope excitation angle: θ C_AP1_1 = 12°, θ C_AP1_2 = 8°, θ C_AP1_3 = 16°, θ C_AP1_4 = 10°, θ C_AP1_5 = 16°, θ C_AP1_6 =9° Second envelope excitation angle: θ C_AP2_1 = 9°, θ C_AP2_2 = 15°, θ C_AP2_3 = 8°, θ C_AP2_4 = 15.5°, θ C_AP2_5 = 10°, θ C_AP2_6 =16° Each reflector: Number of pairs of reflector electrode fingers: 20 pairs

[0258] The design parameters of the series arm resonator S61b differ from those of the series arm resonator S61a only in that the duty ratio is 0.634.

[0259] In the series arm resonator S61c, the excitation angle θ C_prop The duty ratio is 0.5 when the excitation angle θ C_prop The larger the absolute value of the cross angle θ, the smaller the duty ratio. C_AP1 is 7.5°. C_AP2 is -7.5°.

[0260] FIG. 34 is a diagram showing phase characteristics of each excitation angle variable resonator in the sixth embodiment.

[0261] As shown in Fig. 34, in the series arm resonators S61a, S61b, and S61c, which are excitation angle variable resonators, spurious waves are sufficiently suppressed. Furthermore, it can be seen that the frequencies at which spurious waves are generated are different between these series arm resonators. This makes it possible to effectively suppress spurious waves as a whole for the multiple series arm resonators in the series arm resonator section S61. This makes it possible to effectively suppress the influence of spurious waves on filters other than the first filter in the multiplexer.

[0262] As described above, when an unwanted wave occurs in a resonator in the first half, the unwanted wave has a particularly large effect on other filters. In particular, when an unwanted wave occurs in a resonator in the resonator section located closest to the first signal terminal 3A among the multiple resonator sections, the unwanted wave has a larger effect on other filters. In this embodiment, the series arm resonator S61a and the series arm resonator S61c of the series arm resonator section S61 located closest to the first signal terminal 3A have different types of shapes of electrode fingers in a plan view. This makes it possible to make the frequencies at which unwanted waves occur different from each other in both series arm resonators.

[0263] In this specification, the type of shape of the electrode fingers in a plan view refers to types of shapes such as a circular arc or an elliptical arc. The different types of shapes of the electrode fingers in a plan view refer to, for example, a case where one is a circular arc and the other is an elliptical arc, or a case where one is an arc and the other is a curved shape that can be approximated to a circular arc. For example, if the shapes of both electrode fingers in a plan view are curved shapes that can be approximated to a circular arc and any of the constant parameters is different, the types of shapes of both electrode fingers in a plan view are the same. Or, for example, the shapes of both electrode fingers in a plan view are circular arcs and the excitation angle θ C_prop In the present embodiment, the electrode fingers of the series arm resonator S61a and the series arm resonator S61b have the same type of shape in a plan view when viewed from above, when the manner in which any of the parameters changes in response to the change in the electrode fingers differs from that of the series arm resonator S61a.

[0264] The duty ratio of the series arm resonator S61a and the series arm resonator S61b is constant. C_prop The duty ratios at the 0° portion are different from each other. This makes it possible to more reliably make the frequencies at which spurious waves are generated different from each other in both resonators.

[0265] The effect of dispersing frequencies generating unwanted waves in the sixth embodiment will be further shown. The return losses on the common connection terminal side of the first filter in the first embodiment, the sixth embodiment, and the first comparative example were compared. In the first embodiment, all of the excitation angle variable resonators in the series arm resonator section S1 shown in FIG. 3 have the same shape.

[0266] FIG. 35 is a diagram showing return losses in the first embodiment, the sixth embodiment, and the first comparative example.

[0267] 35, in the first and sixth embodiments, the unnecessary waves around 1725 MHz can be suppressed more effectively than in the first comparative example. Furthermore, in the sixth embodiment, the unnecessary waves around 1725 MHz can be suppressed more effectively than in the first embodiment.

[0268] In the following, when the resonator section located closest to the first signal terminal has a plurality of resonators, a preferable configuration will be shown regardless of whether the resonator section is a series arm resonator section or a parallel arm resonator section.

[0269] It is preferable that the resonator section located closest to the first signal terminal includes at least two variable excitation angle resonators, and the at least two variable excitation angle resonators have electrode fingers with different shapes in plan view. As an example, the shape of the electrode fingers in plan view of at least one variable excitation angle resonator included in the resonator section located closest to the first signal terminal is a circular arc. In this case, it is sufficient that the shape of the electrode fingers in plan view of at least one other variable excitation angle resonator is other than a circular arc. This makes it possible to more reliably distribute the frequencies of the unwanted waves generated in the multiple resonators of the resonator section, and more reliably and effectively suppress the unwanted waves.

[0270] It is more preferable that the resonator section located closest to the first signal terminal includes at least three excitation angle variable resonators, and the at least three excitation angle variable resonators in the resonator section have electrode fingers with different shapes in a plan view, thereby more reliably dispersing the frequencies of unwanted waves generated in the multiple resonators in the resonator section and more reliably suppressing unwanted waves effectively.

[0271] In each of at least two excitation angle variable resonators in the resonator portion located closest to the first signal terminal, at least an excitation angle θ C_prop In this case, the duty ratio is constant in the portion where the excitation angle θ is 0° between at least two excitation angle variable resonators in the resonator section. C_prop Alternatively, in each of at least three excitation angle variable resonators in the resonator section located closest to the first signal terminal, at least the duty ratios at the excitation angle θ C_prop In this case, the duty ratio is constant in the portion where the excitation angle θ is 0° between at least three excitation angle variable resonators in the resonator section. C_propIt is more preferable that the duty ratios at the 0° portions are different from each other, so that the frequencies of the spurious waves generated in the multiple resonators of the resonator section can be more reliably dispersed, and the spurious waves can be more reliably and effectively suppressed.

[0272] It is preferable that at least two excitation angle variable resonators included in the resonator section located closest to the first signal terminal have substantially the same resonant frequency or anti-resonant frequency in the crossing region. These excitation angle variable resonators correspond to resonators divided in series or parallel. A large amount of power tends to be applied to the resonator section. In contrast, since the resonators having the desired resonant frequency or anti-resonant frequency are divided in series or parallel, the applied power can be dispersed. Therefore, the resonators having the desired resonant frequency or anti-resonant frequency are less likely to be damaged.

[0273] FIG. 36 is a circuit diagram of a multiplexer according to the seventh embodiment.

[0274] The multiplexer 71 has a first filter 71A, a second filter 71B, a third filter 71C, and a fourth filter 71D. The passband of each filter is the same as in the first and second embodiments.

[0275] The configuration of the first filter 21A is the same as that of the second embodiment. Therefore, all resonators in the series arm resonator section S1 and the parallel arm resonator section P21 located closest to the common connection terminal 7 in the first filter 21A are variable excitation angle resonators. The same is true for each filter other than the first filter. That is, in this embodiment, all resonators in the series arm resonator section and the parallel arm resonator section located closest to the common connection terminal 7 in all filters commonly connected to the common connection terminal 7 are variable excitation angle resonators. This makes it possible to effectively suppress the influence of unwanted waves in all filters in the multiplexer 71.

[0276] The following describes the circuit configurations of the second filter 71B, the third filter 71C, and the fourth filter 71D. Each of the second filter 71B, the third filter 71C, and the fourth filter 71D has a signal terminal, a plurality of series arm resonator units, and a plurality of parallel arm resonator units.

[0277] The multiple series arm resonator sections of the second filter 71B are series arm resonator section S71B, series arm resonator section S72B, series arm resonator section S73B, and series arm resonator section S74B. The series arm resonator section S71B includes three series arm resonators connected in series with each other. The series arm resonator section S72B and the series arm resonator section S74B each include two series arm resonators connected in series with each other. On the other hand, the series arm resonator section S73B is composed of one series arm resonator.

[0278] The series arm resonator section S71B, the series arm resonator section S72B, the series arm resonator section S73B and the series arm resonator section S74B are connected in series to one another in this order from the common connection terminal 7. Of the multiple series arm resonator sections, the series arm resonator section S71B is located closest to the common connection terminal 7.

[0279] The multiple parallel arm resonator sections of the second filter 71B are the parallel arm resonator section P71B, the parallel arm resonator section P72B, the parallel arm resonator section P73B, and the parallel arm resonator section P74B. The parallel arm resonator section P74B includes two parallel arm resonators connected in series to each other. On the other hand, each of the parallel arm resonator sections P71B, P72B, and P73B is composed of one parallel arm resonator.

[0280] The parallel arm resonator section P71B is connected between a node D between the series arm resonator section S71B and the series arm resonator section S72B and the ground potential. The parallel arm resonator section P72B is connected between a node D between the series arm resonator section S72B and the series arm resonator section S73B and the ground potential. The parallel arm resonator section P73B is connected between a node D between the series arm resonator section S73B and the series arm resonator section S74B and the ground potential. The parallel arm resonator section P74B is connected between a node D between the series arm resonator section S74B and the signal terminal 73B and the ground potential. Of the multiple parallel arm resonators, the parallel arm resonator section P71B is located closest to the common connection terminal 7.

[0281] The second filter 71B has an inductor L1 and an inductor L2. The parallel arm resonator unit P72B and the parallel arm resonator unit P73B are commonly connected to the inductor L1. The inductor L1 is connected to a ground potential. The inductor L2 is connected between the parallel arm resonator unit P74B and the ground potential.

[0282] The third filter 71C includes a plurality of series arm resonator sections S71C, S72C, S73C, S74C, and S75C. Each of the series arm resonator section S71C, S72C, S73C, and S74C includes two series arm resonators connected in series to each other. On the other hand, the series arm resonator section S75C includes one series arm resonator.

[0283] The series arm resonator section S71C, the series arm resonator section S72C, the series arm resonator section S73C, the series arm resonator section S74C and the series arm resonator section S75C are connected in series to one another in this order from the common connection terminal 7. Of the multiple series arm resonator sections, the series arm resonator section S71C is located closest to the common connection terminal 7.

[0284] The third filter 71C includes a parallel arm resonator section P71C, a parallel arm resonator section P72C, a parallel arm resonator section P73C, and a parallel arm resonator section P74C. Each of the parallel arm resonator sections of the third filter 71C is formed of one parallel arm resonator.

[0285] The parallel arm resonator unit P71C is connected between a node D between the series arm resonator unit S71C and the series arm resonator unit S72C and the ground potential. The parallel arm resonator unit P72C is connected between a node D between the series arm resonator unit S72C and the series arm resonator unit S73C and the ground potential. The parallel arm resonator unit P73C is connected between a node D between the series arm resonator unit S73C and the series arm resonator unit S74C and the ground potential. The parallel arm resonator unit P74C is connected between a node D between the series arm resonator unit S74C and the series arm resonator unit S75C and the ground potential. Of the multiple parallel arm resonators, the parallel arm resonator unit P71C is located closest to the common connection terminal 7.

[0286] The third filter 71C has a capacitance element C1 and a capacitance element C2. The capacitance elements C1 and C2 are connected in parallel to the series arm resonator section S71C. From the common connection terminal 7 side, the capacitance elements C1 and C2 are connected in series to each other in this order.

[0287] The plurality of series arm resonator sections of the fourth filter 71D are the series arm resonator section S71D, the series arm resonator section S72D, the series arm resonator section S73D, and the series arm resonator section S74D. Each of the series arm resonator section S71D and the series arm resonator section S73D includes three series arm resonators connected in series with each other. Each of the series arm resonator section S72D and the series arm resonator section S74D includes two series arm resonators connected in series with each other.

[0288] The series arm resonator section S71D, the series arm resonator section S72D, the series arm resonator section S73D and the series arm resonator section S74D are connected in series to one another in this order from the common connection terminal 7. Of the multiple series arm resonator sections, the series arm resonator section S71D is located closest to the common connection terminal 7.

[0289] The parallel arm resonator sections of the fourth filter 71D are a parallel arm resonator section P71D, a parallel arm resonator section P72D, a parallel arm resonator section P73D, and a parallel arm resonator section P74D. The parallel arm resonator section P74D includes three parallel arm resonators connected in series to each other. On the other hand, each of the parallel arm resonator sections P71D, P72D, and P73D is composed of one parallel arm resonator.

[0290] The parallel arm resonator section P71D is connected between a node D between the series arm resonator section S71D and the series arm resonator section S72D and the ground potential. The parallel arm resonator section P72D is connected between a node D between the series arm resonator section S72D and the series arm resonator section S73D and the ground potential. The parallel arm resonator section P73D is connected between a node D between the series arm resonator section S73D and the series arm resonator section S74D and the ground potential. The parallel arm resonator section P74D is connected between a node D between the series arm resonator section S74D and the signal terminal 73D and the ground potential. Of the multiple parallel arm resonators, the parallel arm resonator section P71D is located closest to the common connection terminal 7.

[0291] The fourth filter 71D includes an inductor L3 and an inductor L4. The inductor L3 is connected between the parallel arm resonator section P71D and the ground potential. The inductor L4 is connected between the parallel arm resonator section P73D and the ground potential.

[0292] In this embodiment, all of the filters of the multiplexer 71 are mounted on the same mounting board. The communication bands of the multiplexer 71 are Band 1 and Band 3. Specifically, the first filter 71A is a receive filter for Band 1. The second filter 71B is a transmit filter for Band 3. The third filter 71C is a receive filter for Band 3. The fourth filter 71D is a transmit filter for Band 1. However, the multiplexer 71 may include filters that are not mounted on the same mounting board.

[0293] In this case, for example, the multiplexer 71 may have a module substrate on which a mounting substrate is mounted. The first filter 21A, the second filter 71B, the third filter 71C, and the fourth filter 71D, as well as filters that do not share the mounting substrate, may be mounted on the module substrate. The first filter 21A, the second filter 71B, the third filter 71C, and the fourth filter 71D, as well as other filters, may be commonly connected to the common connection terminal 7. The common connection terminal 7 may be provided on the module substrate.

[0294] The multiplexer 71 may have, for example, a receive filter for Band 32 in addition to the transmit filter and receive filter for Band 1 and the transmit filter and receive filter for Band 3. The pass band of the receive filter is 1452 MHz to 1496 MHz.

[0295] The passband of the reception filter tends to include frequencies at which Rayleigh waves are generated in the resonators of the transmission filter of Band 1. However, the fourth filter 71D serving as a resonator of the transmission filter of Band 1 can suppress the influence of the Rayleigh waves, which are unwanted waves, on other filters.

[0296] The multiplexer 71 may have, for example, a transmit filter of Band7, Band41, n77, or n78. Alternatively, the multiplexer 71 may have a receive filter of n77 or n78. The pass band of the transmit filter of Band7 is 2500 MHz to 2570 MHz. The pass band of the transmit filter of Band41 is 2496 MHz to 2690 MHz. The band of n77 is 3300 MHz to 4800 MHz. The band of n78 is 3300 MHz to 4200 MHz.

[0297] There is a risk that frequencies that generate spurious waves in the resonators of other filters are located within the passbands of these transmit filters or receive filters. However, the first filter 21A, the second filter 71B, the third filter 71C, and the fourth filter 71D can suppress the influence of spurious waves generated at frequencies higher than the anti-resonance frequency of the resonators on other filters.

[0298] Incidentally, in the first filter as a filter device according to the present invention, the laminated configuration of the piezoelectric substrate is not limited to the configuration shown in Fig. 4. According to the eighth embodiment, an example will be shown in which the first filter has a piezoelectric substrate different from that of the first embodiment.

[0299] FIG. 37 is a schematic front sectional view of an excitation angle variable resonator of the first filter according to the eighth embodiment.

[0300] This embodiment differs from the first embodiment in the layered configuration of the piezoelectric substrate 82. This embodiment also differs from the first embodiment in that a dielectric film 8 is not provided on the piezoelectric substrate 82. Other than the above, the multiplexer of this embodiment has the same configuration as the multiplexer 1 of the first embodiment.

[0301] The piezoelectric substrate 82 includes a support substrate 4, an intermediate layer 85, and a piezoelectric layer 6. The intermediate layer 85 is provided on the support substrate 4. The piezoelectric layer 6 is provided on the intermediate layer 85. In this embodiment, the intermediate layer 85 has a frame-like shape. That is, the intermediate layer 85 has a through hole. The support substrate 4 closes one end of the through hole of the intermediate layer 85. The piezoelectric layer 6 closes the other end of the through hole of the intermediate layer 85. This forms a hollow portion 82c in the piezoelectric substrate 82. A part of the piezoelectric layer 6 and a part of the support substrate 4 face each other with the hollow portion 82c in between. At least a part of the IDT electrode 18 overlaps with the hollow portion 82c in a plan view.

[0302] In this embodiment, the main mode can be reflected toward the piezoelectric layer 6. Therefore, the energy of the elastic wave can be effectively confined to the piezoelectric layer 6. In addition, similar to the first embodiment, the influence of unwanted waves can be suppressed in the multiplexer.

[0303] The piezoelectric substrate 82 may have a plurality of hollow portions 82c. The plurality of IDT electrodes in the first filter may overlap different hollow portions 82c in a plan view. Alternatively, the plurality of IDT electrodes may overlap the same hollow portion 82c in a plan view.

[0304] Below, a first modified example and a second modified example of the eighth embodiment are shown, which differ from the eighth embodiment only in the laminated structure of the piezoelectric substrate. In the first modified example and the second modified example, the influence of unwanted waves in the multiplexer can be suppressed as in the eighth embodiment. Furthermore, in the first filter, the energy of the elastic wave can be effectively confined on the piezoelectric layer 6 side.

[0305] 38, a piezoelectric substrate 82A has a support substrate 4, an acoustic reflection film 87, an intermediate layer 85A, and a piezoelectric layer 6. The acoustic reflection film 87 is provided on the support substrate 4. The intermediate layer 85A is provided on the acoustic reflection film 87. The piezoelectric layer 6 is provided on the intermediate layer 85A. The intermediate layer 85A is a low acoustic velocity film.

[0306] The acoustic reflection film 87 is a laminate of a plurality of acoustic impedance layers. Specifically, the acoustic reflection film 87 has a plurality of low acoustic impedance layers and a plurality of high acoustic impedance layers. The high acoustic impedance layers are layers with relatively high acoustic impedance. More specifically, the plurality of high acoustic impedance layers of the acoustic reflection film 87 are a high acoustic impedance layer 87a, a high acoustic impedance layer 87c, and a high acoustic impedance layer 87e. On the other hand, the low acoustic impedance layers are layers with relatively low acoustic impedance. More specifically, the plurality of low acoustic impedance layers of the acoustic reflection film 87 are a low acoustic impedance layer 87b and a low acoustic impedance layer 87d. The low acoustic impedance layers and the high acoustic impedance layers are alternately laminated. The high acoustic impedance layer 87a is the layer located closest to the piezoelectric layer 6 in the acoustic reflection film 87.

[0307] The acoustic reflecting film 87 has two low acoustic impedance layers and three high acoustic impedance layers, although it is sufficient that the acoustic reflecting film 87 has at least one low acoustic impedance layer and one high acoustic impedance layer.

[0308] The low acoustic impedance layer may be made of, for example, silicon oxide or aluminum. The high acoustic impedance layer may be made of, for example, a metal such as platinum or tungsten, or a dielectric such as aluminum nitride or silicon nitride. The material of the intermediate layer 85A may be the same as that of the low acoustic impedance layer.

[0309] In the second modified example shown in Fig. 39, a piezoelectric substrate 82B has a support substrate 84 and a piezoelectric layer 6. The piezoelectric layer 6 is provided directly on the support substrate 84. More specifically, the support substrate 84 has a recess. The piezoelectric layer 6 is provided on the support substrate 84 so as to cover the recess. This provides a hollow portion in the piezoelectric substrate 82B. The hollow portion overlaps at least a portion of the IDT electrode 18 in a plan view.

[0310] FIG. 40 is a schematic front sectional view of an excitation angle variable resonator of the first filter according to the ninth embodiment.

[0311] This embodiment differs from the first embodiment in that the IDT electrode 18 is embedded in the protective film 99. Although not shown, other IDT electrodes in the first filter are also embedded in the protective film 99. Except for the above, the multiplexer of this embodiment has the same configuration as the multiplexer 1 of the first embodiment.

[0312] Specifically, a protective film 99 is provided on the piezoelectric layer 6 so as to cover the IDT electrode 18. The thickness of the protective film 99 is greater than the thickness of the IDT electrode 18. The IDT electrode 18 is embedded in the protective film 99. This makes it difficult for the IDT electrode 18 to be damaged.

[0313] The protective film 99 has a first protective layer 99a and a second protective layer 99b. The IDT electrode 18 is embedded in the first protective layer 99a. The second protective layer 99b is provided on the first protective layer 99a. This allows the protective film 99 to provide a number of effects. Specifically, in this embodiment, silicon oxide is used as the material for the first protective layer 99a. This allows the absolute value of the temperature coefficient of frequency (TCF) of each resonator to be reduced. This allows the temperature characteristics of each resonator to be improved. The second protective layer 99b is made of silicon nitride. This allows the moisture resistance to be increased.

[0314] Additionally, in the present embodiment, as in the first embodiment, the influence of unwanted waves in the multiplexer can be suppressed.

[0315] The materials of the first protective layer 99a and the second protective layer 99b are not limited to those mentioned above. The protective film 99 may be a single layer or a laminate of three or more layers.

[0316] FIG. 41 is a schematic front sectional view of an excitation angle variable resonator of the first filter according to the tenth embodiment.

[0317] This embodiment differs from the first embodiment in that an IDT electrode 18 is provided on both the first principal surface 6a and the second principal surface 6b of the piezoelectric layer 6. The IDT electrode 18 provided on the second principal surface 6b is embedded in the second layer 5b of the intermediate layer 5. This embodiment also differs from the first embodiment in that a dielectric film 8 is not provided on the first principal surface 6a. Other than the above, the multiplexer of this embodiment has the same configuration as the multiplexer 1 of the first embodiment.

[0318] The IDT electrode 18 provided on the first principal surface 6a of the piezoelectric layer 6 and the IDT electrode 18 provided on the second principal surface 6b face each other across the piezoelectric layer 6. In this embodiment, as in the first embodiment, the influence of unwanted waves in the multiplexer can be suppressed.

[0319] The IDT electrodes 18 provided on the first principal surface 6a and the second principal surface 6b of the piezoelectric layer 6 may have different design parameters, for example.

[0320] IDT electrodes may be provided on the second main surface 6b of the piezoelectric layer 6 in a portion other than that shown in Fig. 41. For example, in the first filter, IDT electrodes may face each other with the piezoelectric layer 6 interposed therebetween in a portion other than that shown in Fig. 41.

[0321] The following describes first to third modified examples of the tenth embodiment, which differ from the tenth embodiment only in at least one of the configuration of the electrodes provided on the second main surface of the piezoelectric layer and the laminated configuration of the piezoelectric substrate. In the first to third modified examples, as in the tenth embodiment, the influence of unwanted waves can be suppressed in the multiplexer.

[0322] 42, a piezoelectric substrate 82 is configured similarly to the eighth embodiment. Specifically, the piezoelectric substrate 82 has a support substrate 4, an intermediate layer 85, and a piezoelectric layer 6. The IDT electrode 18 provided on the second main surface 6b of the piezoelectric layer 6 is located in a hollow portion 82c.

[0323] In a second modified example shown in FIG. 43, a plate-shaped electrode 118 is provided on the second main surface 6b of the piezoelectric layer 6. The electrode 118 is embedded in the second layer 5b of the intermediate layer 5. The IDT electrode 18 and the electrode 118 face each other with the piezoelectric layer 6 interposed therebetween. Note that other electrodes 118 may be provided on the second main surface 6b of the piezoelectric layer 6 in a portion other than that shown in FIG. 43. For example, the IDT electrode and the electrode 118 may face each other with the piezoelectric layer 6 interposed therebetween in a portion of the first filter other than that shown in FIG. 43.

[0324] 44, a piezoelectric substrate 82 is configured similarly to the first modified example, and an electrode 118 similar to that of the second modified example is provided on a second main surface 6b of a piezoelectric layer 6. The electrode 118 is located in a hollow portion 82c. The IDT electrode 18 and the electrode 118 face each other with the piezoelectric layer 6 interposed therebetween.

[0325] Examples of configurations of the elastic wave device according to the present invention will be described below.

[0326] <1> a first signal terminal and a second signal terminal, and a plurality of resonators including a plurality of series arm resonators and a plurality of parallel arm resonators, at least one of the plurality of series arm resonators and the plurality of parallel arm resonators is an excitation angle variable resonator, the excitation angle variable resonator has a piezoelectric substrate including a piezoelectric layer, and an IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, the piezoelectric layer has a propagation axis, the plurality of electrode fingers are curved, an excitation direction of an elastic wave in an arbitrary portion of an arbitrary electrode finger among the plurality of electrode fingers is any one of first to third directions, the first direction is a direction perpendicular to a direction in which the electrode finger extends, the second direction is a direction connecting the electrode finger and the electrode finger adjacent to the electrode finger, the third direction is a direction of an electric field vector generated between the electrode finger and the electrode finger adjacent to the electrode finger, and the excitation direction is formed by a direction in which the propagation axis extends. a first half of the ladder sections is a first half of the ladder sections, and a first half of the ladder sections is a first half of the ladder sections, the first half of the ladder sections being a first resonator that is closest to the first signal terminal and the second resonator that is closest to the second signal terminal, and a first half of the ladder sections is a first half of the ladder sections, the first half of the ladder sections being a first half of the ladder sections, and a first half of the ladder sections being a first half of the ladder sections, the first half of the ladder sections being a second half of the ladder sections, the second half of the ladder sections being a first half of the ladder sections, the first half of the ladder sections being a second half of the ladder sections, the first half of the ladder sections being a second half of the ladder sections, the second half of the ladder sections being a first half of the ladder sections,

[0327] <2> the first signal terminal is connected to an antenna; <1> The filter device according to claim 1 .

[0328] <3> In the IDT electrode of at least one of the excitation angle changing resonators, the shape of the plurality of electrode fingers in a plan view includes a circular arc shape or an elliptical arc shape. <1> or <2> The filter device according to claim 1 .

[0329] <4> the plurality of electrode fingers in the IDT electrode of at least one of the excitation angle changing resonators include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips at the tips of the plurality of second electrode fingers is a first envelope, a virtual line formed by connecting the tips at the tips of the plurality of first electrode fingers is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is an intersection region, the region includes a portion of the first electrode finger located on the first envelope, and a portion adjacent to the tip of any of the second electrode fingers is an adjacent portion of the first electrode finger, the portion being located on the second envelope of the second electrode finger. a portion adjacent to the tip portion of any of the first electrode fingers is an adjacent portion of the second electrode finger, the intersection region includes at least one curved region in which the shapes of the plurality of first electrode fingers and the plurality of second electrode fingers are curved in a plan view, the at least one curved region includes the curved region whose one end edge is the first envelope, and in the curved region, the curvature of each of the first electrode fingers and the second electrode fingers is not constant, and the curvatures are different between the tip portions located on the first envelope side, between the adjacent portions, or between the tip portion and the adjacent portion, in at least one pair of electrode fingers among the plurality of first electrode fingers and the plurality of second electrode fingers. <1> or <2> The filter device according to claim 1 .

[0330] <5> At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode interposed therebetween, and includes a pair of reflectors each having a plurality of reflector electrode fingers, and a shape of the plurality of reflector electrode fingers in a plan view includes a curved shape. <3> or <4> The filter device according to claim 1 .

[0331] <6> The plurality of electrode fingers in the IDT electrode of at least one of the excitation angle changing resonators include a plurality of first electrode fingers and a plurality of second electrode fingers that are interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers is a first envelope, a virtual line formed by connecting the tips of the plurality of first electrode fingers is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a cross region, and the cross region is a region where the plurality of first electrode fingers are interdigitated with each other. the electrode fingers and the second electrode fingers extend in parallel to each other, and a non-parallel region in which the directions in which the first electrode fingers and the second electrode fingers extend cross each other, the parallel regions and the non-parallel regions are alternately arranged in at least a part of the crossing region, and the first electrode fingers and the second electrode fingers each extend linearly in the parallel regions and the non-parallel regions, and are bent at the boundaries between the parallel regions and the non-parallel regions. <1> or <2> The filter device according to claim 1 .

[0332] <7> At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode interposed therebetween, and has a pair of reflectors each having a plurality of reflector electrode fingers, and a shape of the plurality of reflector electrode fingers in a plan view includes a shape bent at a plurality of nodes. <6> The filter device according to claim 1 .

[0333] <8> At least one of an electrode finger pitch and a duty ratio is constant in a portion of the IDT electrode of at least one of the excitation angle variable resonators where the excitation angle is the same. <1> ~ <7> 13. A filter device according to any one of claims 1 to 12.

[0334] <9> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a crossing region, and a resonant frequency or an anti-resonant frequency is approximately the same in the crossing region of at least one of the excitation angle variable resonators; <1> ~ <8> 13. A filter device according to any one of claims 1 to 12.

[0335] <10> a path connecting the first signal terminal and the second signal terminal is a series arm, paths branching from the series arm to a ground potential are parallel arms, and connection points of the series arm and the parallel arm are nodes; when one series arm resonator or a group of a plurality of the series arm resonators connected in series to each other without passing through the node is defined as a series arm resonator section, a plurality of the series arm resonator sections are configured in the series arm, and a plurality of series arm resonator sections are connected in series between the first signal terminal and the series arm resonator section, between the second signal terminal and the series arm resonator section, and between adjacent series arm resonator sections, and when each of the sections between adjacent series arm resonator sections is defined as a section, at least one of the nodes is located in each of the sections between adjacent series arm resonator sections, and when the parallel arm resonators located in the parallel arm connected to the nodes located in the same section are defined as one parallel arm resonator section, a plurality of the parallel arm resonator sections are configured, and at least one of the series arm resonator section located closest to the first signal terminal and the parallel arm resonator section located closest to the first signal terminal is the excitation angle variable resonator. <1> ~ <9> 13. A filter device according to any one of claims 1 to 12.

[0336] <11> when the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are regarded as a plurality of resonator sections, at least one of the resonators in the resonator section located closest to the first signal terminal side is the excitation angle variable resonator. <10> The filter device according to claim 1 .

[0337] <12> the resonator section located closest to the first signal terminal includes a plurality of the resonators, and at least half of the resonators are the excitation angle variable resonators; <11> The filter device according to claim 1 .

[0338] <13> When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are regarded as a plurality of resonator sections, the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least two of the resonators are the excitation angle variable resonators, and the at least two excitation angle variable resonators in the resonator section located closest to the first signal terminal have electrode fingers having different types of shapes in a plan view. <10> ~ <12> 13. A filter device according to any one of claims 1 to 12.

[0339] <14> When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are taken as a plurality of resonator sections, the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least two of the resonators are the excitation angle variable resonators, and each of the at least two excitation angle variable resonators in the resonator section located closest to the first signal terminal has a constant duty ratio at least in a portion where the excitation angle is 0°, and the at least two excitation angle variable resonators in the resonator section located closest to the first signal terminal have different duty ratios at a portion where the excitation angle is 0°. <10> ~ <13> 13. A filter device according to any one of claims 1 to 12.

[0340] <15> the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least three of the plurality of resonators are the excitation angle variable resonators, and the at least three excitation angle variable resonators in the resonator section located closest to the first signal terminal have electrode fingers having different shapes in a plan view. <13> or <14> The filter device according to claim 1 .

[0341] <16> the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least three of the plurality of resonators are the excitation angle variable resonators, and each of the at least three excitation angle variable resonators in the resonator section located closest to the first signal terminal has a constant duty ratio at least in a portion where the excitation angle is 0°, and the at least three excitation angle variable resonators in the resonator section located closest to the first signal terminal have different duty ratios at a portion where the excitation angle is 0°. <13> ~ <15> 13. A filter device according to any one of claims 1 to 12.

[0342] <17> In at least one of the excitation angle variable resonators included in the resonator portion located closest to the first signal terminal, the shape of the electrode fingers in a plan view is a circular arc, and in at least one other of the excitation angle variable resonators, the shape of the electrode fingers in a plan view is other than a circular arc. <13> or <15> The filter device according to claim 1 .

[0343] <18> When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are regarded as a plurality of resonator sections, the resonator section located closest to the first signal terminal side includes a plurality of the resonators, at least two of the plurality of resonators are the excitation angle variable resonators, the plurality of electrode fingers in the IDT electrode of each of the excitation angle variable resonators include a plurality of first electrode fingers and a plurality of second electrode fingers which are interdigitated with each other, and in each of the excitation angle variable resonators, a virtual line formed by connecting the tips of the first electrode fingers at the tips is defined as a first envelope, a virtual line formed by connecting the tips of the first electrode fingers at the tips is defined as a second envelope, a region in the IDT electrode between the first envelope and the second envelope is a crossing region, and resonant frequencies or anti-resonant frequencies are approximately the same in the crossing region, and at least two of the excitation angle change type resonators included in the resonator portion located closest to the first signal terminal have resonant frequencies or anti-resonant frequencies approximately the same in the crossing region. <10> ~ <17> 13. A filter device according to any one of claims 1 to 12.

[0344] <19> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a crossing region, and in at least one of the excitation angle variable resonators, at least one of the first envelope and the second envelope has at least one bend where an extending direction is changed. <1> ~ <18> 13. A filter device according to any one of claims 1 to 12.

[0345] <20> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a crossing region, and in at least one of the excitation angle variable resonators, at least one of the first envelope and the second envelope is linear. <1> ~ <18> 13. A filter device according to any one of claims 1 to 12.

[0346] <21> the plurality of electrode fingers in the IDT electrode of the excitation angle variable resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, a virtual line formed by connecting the tips of the plurality of second electrode fingers at their tips is a first envelope, and a virtual line formed by connecting the tips of the plurality of first electrode fingers at their tips is a second envelope, a region between the first envelope and the second envelope in the IDT electrode is an intersection region, the intersection region has a first edge region including the first envelope, a second edge region including the second envelope, and a central region sandwiched between the first edge region and the second edge region, and in at least one of the excitation angle variable resonators, a low acoustic velocity region is formed in at least a part of at least one of the first edge region and the second edge region, in which the acoustic velocity is lower than the acoustic velocity in the central region. <1> ~ <20> 13. A filter device according to any one of claims 1 to 12.

[0347] <22> In at least one of the first edge region and the second edge region, at least one of the electrode fingers has a wide portion that is wider than a width in the central region, thereby forming the low acoustic velocity region. <21> The filter device according to claim 1 .

[0348] <23> a mass-adding film is further provided in at least one of the first edge region and the second edge region so as to overlap at least one of the plurality of first electrode fingers and the plurality of second electrode fingers when viewed in a plan view, and the low acoustic velocity region is configured by providing the mass-adding film. <21> or <22> The filter device according to claim 1 .

[0349] <24> a thickness of at least one of the electrode fingers in at least one of the first edge region and the second edge region is greater than a thickness of the electrode finger in the central region, thereby forming the low acoustic velocity region. <21> ~ <23> 13. A filter device according to any one of claims 1 to 12.

[0350] <25> The low sound velocity region is configured throughout both the first edge region and the second edge region. <21> ~ <24> 13. A filter device according to any one of claims 1 to 12.

[0351] <26> a longitudinally coupled resonator type acoustic wave filter in which a path connecting the first signal terminal and the second signal terminal is a series arm, and the plurality of resonators are located in the series arm; <1> ~ <25> 13. A filter device according to any one of claims 1 to 12.

[0352] <27> The piezoelectric substrate has a support substrate, and the piezoelectric layer is provided on the support substrate. <1> ~ <26> 13. A filter device according to any one of claims 1 to 12.

[0353] <28> The piezoelectric substrate has an intermediate layer provided between the support substrate and the piezoelectric layer. <27> The filter device according to claim 1 .

[0354] <29> a hollow portion is formed in the piezoelectric substrate, and a part of the support substrate and a part of the piezoelectric layer face each other with the hollow portion interposed therebetween; <28> The filter device according to claim 1 .

[0355] <30> The piezoelectric substrate is composed of only the piezoelectric layer. <1> ~ <26> 13. A filter device according to any one of claims 1 to 12.

[0356] <31> all of the resonators share the same piezoelectric substrate; <1> ~ <30> 13. A filter device according to any one of claims 1 to 12.

[0357] <32> A common connection terminal and a plurality of filters including a first filter and a second filter, which are commonly connected to the common connection terminal, at least the first filter of the plurality of filters <1> ~ <31> 13. A multiplexer, which is a filter device according to any one of claims 1 to 12.

[0358] <33> the plurality of filters share the same piezoelectric substrate; <32> 2. A multiplexer according to claim 1 .

[0359] <34> a mounting substrate, wherein at least the second filter of the plurality of filters has a substrate different from the piezoelectric substrate of the first filter, and the plurality of filters are mounted on the mounting substrate. <32> 2. A multiplexer according to claim 1 .

[0360] <35> a passband of the first filter is positioned higher than a passband of the second filter, and the passband of the second filter includes at least a part of frequencies that are 0.5 to 0.9 times the resonant frequency of at least one of the excitation angle-changing resonators in the first filter; <32> ~ <34> 2. A multiplexer according to claim 1 .

[0361] <36> The passband of the first filter is located on the lower side than the passband of the second filter. <32> ~ <34> 2. A multiplexer according to claim 1 . [Explanation of symbols]

[0362] 1...Multiplexer 1A~1D...1st to 4th filters 2...Piezoelectric substrate 3...Support member 3A, 3B: First and second signal terminals 4…Support substrate 5. Middle class 5a, 5b...First and second layers 6...Piezoelectric layer 6a, 6b...First and second principal surfaces 7…Common connection terminal 8...Dielectric film 9A~9H…Reflector 9a, 9b...Reflector busbar 9c...Multiple reflector electrode fingers 9d, 9e…Reflector busbar 9f...Multiple reflector electrode fingers 12, 12B, 12C, 12H...First offset electrode 13, 13B, 13C, 13H...Second offset electrode 14,14A…First busbar 15,15A…Second busbar 16, 16B, 16C, 16E to 16G: First electrode fingers 16a, 16b…Wide section 17, 17B, 17C, 17E to 17G: Second electrode fingers 17a, 17b…Wide section 18,18A~18H…IDT electrode 19... Mass-added membrane 21A, 31A, 41A, 51A...First filter 55...Vertical coupling resonator type acoustic wave filter 71...Multiplexer 71B~71D: 2nd~4th filters 73B,73D…Signal terminal 82, 82A, 82B...Piezoelectric substrate 82c…Hollow part 84…Support substrate 85,85A…middle layer 87…Acoustic reflective film 87a…High acoustic impedance layer 87b…Low acoustic impedance layer 87c…High acoustic impedance layer 87d…Low acoustic impedance layer 87e…High acoustic impedance layer 99…Protective film 99a, 99b...First and second protective layers 118...Electrode A...Parallel area B…Non-parallel region C1, C2...capacitive elements D…Node E1, E1A…First envelope E2, E2A: Second envelope F…Central area H1, H2: First and second edge areas J...Cross area K1, K2: First and second curve regions L, L1 to L4: Inductors P…parallel arm P1~P4,P21,P31~P34,P51,P52,P71B~P71D,P72B~P72D,P73B~P73D,P74B~P74D...Parallel arm resonator section P31a, P31b, P51a, P51b...Parallel arm resonators S: Series arm S1 to S5, S31 to S34, S51 to S53, S61, S71B to S71D, S72B to S72D, S73B to S73D, S74B to S74D, S75C...Series arm resonator section S1a to S1c, S2a, S2b, S3a to S3c, S31a, S31b, S32a to S32c, S51a, S51b, S53a, S53b, S61a to S61c...Series arm resonators V1, V2: Bend W1~W3: 1st to 3rd regions

Claims

1. a first signal terminal and a second signal terminal; a plurality of resonators including a plurality of series arm resonators and a plurality of parallel arm resonators; Equipped with at least one of the plurality of series arm resonators and the plurality of parallel arm resonators is an excitation angle variable resonator, the excitation angle changing resonator has a piezoelectric substrate including a piezoelectric layer, and an IDT electrode including a plurality of electrode fingers provided on the piezoelectric substrate, the piezoelectric layer has a propagation axis, the plurality of electrode fingers are curved, an excitation direction of an acoustic wave in an arbitrary portion of an arbitrary electrode finger among the plurality of electrode fingers is any one of first to third directions, the first direction being a direction perpendicular to a direction in which the electrode finger extends, the second direction being a direction connecting the electrode finger and an electrode finger adjacent to the electrode finger by a shortest distance, and the third direction being a direction of an electric field vector generated between the electrode finger and an electrode finger adjacent to the electrode finger, When an angle between the excitation direction and a direction in which the propagation axis extends is defined as an excitation angle, the excitation angle is not uniform in the IDT electrode of the excitation angle variable resonator, when a pair of adjacent series arm resonators and parallel arm resonators is regarded as one ladder section, a plurality of the ladder sections are formed between the first signal terminal and the second signal terminal, and at least one of the series arm resonators and the parallel arm resonators in the adjacent ladder sections are different resonators from each other, a first half of the ladder sections is defined as the half of all the ladder sections that is located on the first signal terminal side, and a first half of the resonators is defined as the resonators from the resonator located closest to the first signal terminal to the series arm resonator and the parallel arm resonator of the ladder section located closest to the second signal terminal in the first half of the ladder section, wherein at least one of the first half resonators is the variable excitation angle resonator.

2. 2. The filter device of claim 1, wherein the first signal terminal is connected to an antenna.

3. 2. The filter device according to claim 1, wherein in the IDT electrode of at least one of the excitation angle changing resonators, the shape of the plurality of electrode fingers in a plan view includes a shape of a circular arc or an elliptical arc.

4. the plurality of electrode fingers in the IDT electrode of at least one of the excitation angle changing resonators include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; a portion of the first electrode finger including a portion located on the first envelope and adjacent to the tip portion of any of the second electrode fingers is an adjacent portion of the first electrode finger, and a portion of the second electrode finger including a portion located on the second envelope and adjacent to the tip portion of any of the first electrode fingers is an adjacent portion of the second electrode finger, the intersection region includes at least one curved region in which the shapes of the first electrode fingers and the second electrode fingers are curved in a plan view, the at least one curved region including the curved region having one edge that is the first envelope curve; 2. The filter device according to claim 1, wherein in the curved region, the curvature of each of the first electrode fingers and the second electrode fingers is not constant, and the curvature is different between the tip portions, between the adjacent portions, or between the tip portion and the adjacent portion, located on the first envelope side in at least one pair of electrode fingers among the plurality of first electrode fingers and the plurality of second electrode fingers.

5. At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode therebetween, and includes a pair of reflectors each having a plurality of reflector electrode fingers; The filter device according to claim 3 , wherein a shape of the plurality of reflector electrode fingers in a plan view includes a curved shape.

6. the plurality of electrode fingers in the IDT electrode of at least one of the excitation angle changing resonators include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the second electrode fingers is a first envelope, an imaginary line formed by connecting the tips of the first electrode fingers is a second envelope, and a region in the IDT electrode between the first envelope and the second envelope is an intersection region; 2. The filter device according to claim 1, wherein the intersection region includes a plurality of parallel regions in which the first electrode fingers and the second electrode fingers extend in parallel, and a non-parallel region in which the extension directions of the first electrode fingers and the second electrode fingers intersect with each other, the parallel regions and the non-parallel regions are alternately arranged in at least a part of the intersection region, and the first electrode fingers and the second electrode fingers each extend linearly in the parallel regions and the non-parallel regions, and are bent at the boundaries between the parallel regions and the non-parallel regions.

7. At least one of the excitation angle changing resonators is provided on the piezoelectric layer so as to face each other with the IDT electrode therebetween, and includes a pair of reflectors each having a plurality of reflector electrode fingers; The filter device according to claim 6 , wherein a shape of the plurality of reflector electrode fingers in a plan view includes a shape bent at a plurality of nodes.

8. 2. The filter device according to claim 1, wherein at least one of an electrode finger pitch and a duty ratio is constant in a portion of the IDT electrode of at least one of the excitation angle variable resonators where the excitation angle is the same.

9. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; 2. The filter device according to claim 1, wherein at least one of the excitation angle changing resonators has a resonant frequency or an anti-resonant frequency that is substantially the same in the crossing region.

10. a path connecting the first signal terminal and the second signal terminal is a series arm, paths branching from the series arm to a ground potential are parallel arms, and connection points of the series arm and the parallel arm are nodes, when one of the series arm resonators or a group of the series arm resonators connected in series to each other without the node is defined as a series arm resonator section, a plurality of the series arm resonator sections are configured in the series arm, when a section is defined as a section between the first signal terminal and the series arm resonator unit, a section between the second signal terminal and the series arm resonator unit, and a section between adjacent series arm resonator units, at least one of the nodes is located in each of the sections at least between adjacent series arm resonator units, when the parallel arm resonators located in the parallel arm connected to the nodes located in the same section are regarded as one parallel arm resonator unit, a plurality of the parallel arm resonator units are configured, 2. The filter device according to claim 1, wherein at least one of the series arm resonator section located closest to the first signal terminal and the parallel arm resonator section located closest to the first signal terminal is the excitation angle variable resonator.

11. 11. The filter device according to claim 10, wherein when the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are considered as a plurality of resonator sections, at least one of the resonators in the resonator section located closest to the first signal terminal side is the excitation angle variable resonator.

12. 12. The filter device according to claim 11, wherein the resonator section located closest to the first signal terminal includes a plurality of the resonators, and more than half of the plurality of resonators are the excitation angle variable resonators.

13. When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are defined as a plurality of resonator sections, the resonator section located closest to the first signal terminal includes a plurality of the resonators, and at least two of the resonators are the excitation angle variable resonators, 11. The filter device according to claim 10, wherein at least two of the excitation angle changing resonators in the resonator portion located closest to the first signal terminal have electrode fingers having different types of shapes in a plan view.

14. When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are defined as a plurality of resonator sections, the resonator section located closest to the first signal terminal includes a plurality of the resonators, and at least two of the resonators are the excitation angle variable resonators, In each of at least two of the variable excitation angle resonators in the resonator portion located closest to the first signal terminal, a duty ratio is constant at least in a portion where the excitation angle is 0°, 11. The filter device according to claim 10, wherein at least two of the variable excitation angle resonators in the resonator section located closest to the first signal terminal have different duty ratios in the portion where the excitation angle is 0°.

15. the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least three of the resonators being the excitation angle variable resonators; 14. The filter device according to claim 13, wherein at least three of the excitation angle changing resonators in the resonator portion located closest to the first signal terminal have electrode fingers having different types of shapes in a plan view.

16. the resonator section located closest to the first signal terminal includes a plurality of the resonators, at least three of the resonators being the excitation angle variable resonators; In each of at least three of the variable excitation angle resonators in the resonator portion located closest to the first signal terminal, a duty ratio is constant at least in a portion where the excitation angle is 0°, 14. The filter device according to claim 13, wherein at least three of the variable excitation angle resonators in the resonator section located closest to the first signal terminal have different duty ratios in the portion where the excitation angle is 0°.

17. The filter device according to claim 13, wherein in at least one of the excitation angle variable resonators included in the resonator portion located closest to the first signal terminal, the shape of the electrode fingers in a planar view is a circular arc, and in at least one other of the excitation angle variable resonators, the shape of the electrode fingers in a planar view is other than a circular arc.

18. When the plurality of series arm resonator sections and the plurality of parallel arm resonator sections are defined as a plurality of resonator sections, the resonator section located closest to the first signal terminal includes a plurality of the resonators, and at least two of the resonators are the excitation angle variable resonators, the plurality of electrode fingers in the IDT electrode of each of the excitation angle changing resonators include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, In each of the excitation angle changing resonators, an imaginary line formed by connecting the tips of the second electrode fingers at their tips is defined as a first envelope, an imaginary line formed by connecting the tips of the first electrode fingers at their tips is defined as a second envelope, a region between the first envelope and the second envelope in the IDT electrode is a crossing region, and a resonant frequency or an anti-resonant frequency is approximately equal in the crossing region, The filter device according to claim 10, wherein at least two of the excitation angle changing resonators included in the resonator section located closest to the first signal terminal have substantially the same resonant frequency or anti-resonant frequency in the crossing region.

19. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; 2. The filter device according to claim 1, wherein in at least one of the excitation angle changing resonators, at least one of the first envelope and the second envelope has at least one bent portion where the extending direction changes.

20. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; 2. The filter device according to claim 1, wherein in at least one of the excitation angle changing resonators, at least one of the first envelope curve and the second envelope curve is linear.

21. the plurality of electrode fingers in the IDT electrode of the excitation angle changing resonator include a plurality of first electrode fingers and a plurality of second electrode fingers interdigitated with each other, an imaginary line formed by connecting the tips of the tip portions of the plurality of second electrode fingers is defined as a first envelope curve, an imaginary line formed by connecting the tips of the tip portions of the plurality of first electrode fingers is defined as a second envelope curve, and a region in the IDT electrode between the first envelope curve and the second envelope curve is a crossing region; the intersection region has a first edge region including the first envelope curve, a second edge region including the second envelope curve, and a central region sandwiched between the first edge region and the second edge region, 2. The filter device according to claim 1, wherein in at least one of the excitation angle changing resonators, a low sound velocity region is formed in at least a portion of at least one of the first edge region and the second edge region, the sound velocity being lower than the sound velocity in the central region.

22. 22. The filter device according to claim 21, wherein in at least one of the first edge region and the second edge region, at least one of the electrode fingers has a wide portion that is wider than its width in the central region, thereby forming the low acoustic velocity region.

23. a mass-adding film provided in at least one of the first edge region and the second edge region so as to overlap at least one of the first electrode fingers and the second electrode fingers in a plan view; 23. The filter device according to claim 21, wherein the low sound velocity region is configured by providing the mass-adding film.

24. 22. The filter device according to claim 21, wherein the low acoustic velocity region is formed by a thickness of at least one of the electrode fingers in the first edge region and the second edge region being thicker than a thickness of the electrode finger in the central region.

25. 22. The filtering apparatus of claim 21, wherein the low sound velocity region is configured throughout both the first edge region and the second edge region.

26. a path connecting the first signal terminal and the second signal terminal is a series arm, 2. The filter device according to claim 1, wherein the plurality of resonators include a longitudinally coupled resonator type acoustic wave filter located in the series arm.

27. the piezoelectric substrate has a support substrate; The filter device according to claim 1 , wherein the piezoelectric layer is provided on the supporting substrate.

28. 28. The filter device of claim 27, wherein the piezoelectric substrate includes an intermediate layer disposed between the support substrate and the piezoelectric layer.

29. 29. The filter device according to claim 28, wherein a hollow portion is defined in the piezoelectric substrate, and a part of the support substrate and a part of the piezoelectric layer face each other with the hollow portion interposed therebetween.

30. 2. The filter device according to claim 1, wherein the piezoelectric substrate consists of the piezoelectric layer alone.

31. 2. A filter arrangement as claimed in claim 1, wherein all said resonators share the same piezoelectric substrate.

32. A common connection terminal; a plurality of filters including a first filter and a second filter, the filters being commonly connected to the common connection terminal; Equipped with A multiplexer, wherein at least the first filter of the plurality of filters is the filter device of claim 1 .

33. 33. The multiplexer of claim 32, wherein the filters share the same piezoelectric substrate.

34. Further comprising a mounting board; at least the second filter of the plurality of filters has a substrate different from the piezoelectric substrate of the first filter; 33. The multiplexer of claim 32, wherein the plurality of filters are mounted on the mounting substrate.

35. the passband of the first filter is located higher than the passband of the second filter, 33. The multiplexer according to claim 32, wherein a passband of the second filter includes at least a portion of a frequency range that is 0.5 to 0.9 times the resonant frequency of at least one of the excitation angle-changing resonators in the first filter.

36. 33. The multiplexer of claim 32, wherein the passband of the first filter is lower than the passband of the second filter.

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