Filter device and multiplexer
阅读说明:本技术 滤波器装置以及多工器 (Filter device and multiplexer ) 是由 荒木正人 于 2019-12-26 设计创作,主要内容包括:滤波器装置(40)具备:滤波器电路(10),与端子(130以及140)连接,包含第1弹性波谐振器,将第1频带作为通带;以及附加电路(30),与至少一个第1弹性波谐振器并联地连接在端子(130)与端子(140)之间,包含第2弹性波谐振器,附加电路(30)的机电耦合系数与滤波器电路(10)的机电耦合系数不同。(A filter device (40) is provided with: a filter circuit (10) connected to the terminals (130 and 140), including a 1 st elastic wave resonator, and having a 1 st frequency band as a passband; and an additional circuit (30) connected in parallel with at least one 1 st elastic wave resonator between the terminal (130) and the terminal (140), including a 2 nd elastic wave resonator, wherein the additional circuit (30) has an electromechanical coupling coefficient different from that of the filter circuit (10).)
1. A filter device is provided with:
a 1 st terminal and a 2 nd terminal;
a 1 st filter circuit connected to the 1 st terminal and the 2 nd terminal, including a 1 st elastic wave resonator, and having a 1 st frequency band as a passband; and
an additional circuit connected between the 1 st terminal and the 2 nd terminal in parallel with at least one of the 1 st elastic wave resonators, including a 2 nd elastic wave resonator,
the electromechanical coupling coefficient of the additional circuit is different from the electromechanical coupling coefficient of the 1 st filter circuit.
2. The filter arrangement of claim 1,
the electromechanical coupling coefficient of the additional circuit is larger than that of the 1 st filter circuit.
3. The filter arrangement of claim 2,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body and a 1 st interdigital transducer electrode, namely, a 1 st IDT electrode; and
a 1 st dielectric layer formed between the 1 st piezoelectric body and the 1 st IDT electrode,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body; and
and a 2 nd IDT electrode formed in contact with the 2 nd piezoelectric body.
4. The filter arrangement of claim 2,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body and a 1 st IDT electrode; and
a 1 st dielectric layer formed between the 1 st piezoelectric body and the 1 st IDT electrode for adjusting an electromechanical coupling coefficient,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body and a 2 nd IDT electrode; and
a 2 nd dielectric layer formed between the 2 nd piezoelectric body and the 2 nd IDT electrode for adjusting an electromechanical coupling coefficient,
the 2 nd dielectric layer is thinner than the 1 st dielectric layer.
5. The filter arrangement of claim 2,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body and a 1 st IDT electrode; and
a 3 rd dielectric layer formed to cover the 1 st IDT electrode and adjust an electromechanical coupling coefficient,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body and a 2 nd IDT electrode; and
a 4 th dielectric layer formed to cover the 2 nd IDT electrode and adjust an electromechanical coupling coefficient,
the 4 th dielectric layer is thinner than the 3 rd dielectric layer.
6. The filter arrangement according to any one of claims 3 to 5,
the 1 st piezoelectric body and the 2 nd piezoelectric body are one continuous piezoelectric body.
7. The filter arrangement of claim 1,
the electromechanical coupling coefficient of the additional circuit is smaller than that of the 1 st filter circuit.
8. The filter arrangement of claim 7,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body; and
a 1 st IDT electrode formed in contact with the 1 st piezoelectric body,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body and a 2 nd IDT electrode; and
and a 2 nd dielectric layer formed between the 2 nd piezoelectric body and the 2 nd IDT electrode, and adjusting an electromechanical coupling coefficient.
9. The filter arrangement of claim 7,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body and a 1 st IDT electrode; and
a 1 st dielectric layer formed between the 1 st piezoelectric body and the 1 st IDT electrode for adjusting an electromechanical coupling coefficient,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body and a 2 nd IDT electrode; and
a 2 nd dielectric layer formed between the 2 nd piezoelectric body and the 2 nd IDT electrode for adjusting an electromechanical coupling coefficient,
the 2 nd dielectric layer is thicker than the 1 st dielectric layer.
10. The filter arrangement of claim 7,
the 1 st elastic wave resonator includes:
a 1 st piezoelectric body and a 1 st IDT electrode; and
a 3 rd dielectric layer formed to cover the 1 st IDT electrode and adjust an electromechanical coupling coefficient,
the 2 nd elastic wave resonator includes:
a 2 nd piezoelectric body and a 2 nd IDT electrode; and
a 4 th dielectric layer formed to cover the 2 nd IDT electrode and adjust an electromechanical coupling coefficient,
the 4 th dielectric layer is thicker than the 3 rd dielectric layer.
11. The filter arrangement according to any one of claims 8 to 10,
the 1 st piezoelectric body and the 2 nd piezoelectric body are one continuous piezoelectric body.
12. A multiplexer includes:
a common terminal;
the filter arrangement of any one of claims 1 to 11, said 1 st terminal being connected to said common terminal; and
and a 2 nd filter circuit connected to the common terminal and having a 2 nd frequency band different from the 1 st frequency band as a pass band.
13. A multiplexer includes:
a common terminal;
the filter arrangement of any one of claims 7 to 11, said 1 st terminal being connected to said common terminal; and
a 2 nd filter circuit connected to the common terminal and having a 2 nd frequency band different from the 1 st frequency band as a pass band,
the filter device and the filter other than the 2 nd filter circuit are not connected to the common terminal.
14. A multiplexer includes:
a common terminal;
the filter arrangement of any one of claims 2 to 6, said 1 st terminal being connected to said common terminal;
a 2 nd filter circuit connected to the common terminal and having a 2 nd frequency band different from the 1 st frequency band as a pass band; and
and a 3 rd filter circuit connected to the common terminal, and having a 3 rd band as a pass band, the 3 rd band being different from the 1 st band and the 2 nd band and being located between the 1 st band and the 2 nd band.
Technical Field
The invention relates to a filter device and a multiplexer.
Background
In recent years, there is a demand for a mobile phone that can support a plurality of frequency bands and a plurality of radio systems, i.e., a mobile phone that can support so-called multi-band and multi-mode. In order to cope with this, it is required for one filter device to enhance the attenuation characteristics of a frequency band corresponding to the pass band of the other filter device.
Prior art documents
Patent document
Patent document 1: japanese patent laid-open publication No. 2013-118611
Disclosure of Invention
Problems to be solved by the invention
In the transmission filter circuit described in
The present invention has been made to solve the above-described problems, and an object thereof is to provide a small-sized filter device and a multiplexer having high attenuation characteristics corresponding to a bandwidth of an attenuation band.
Means for solving the problems
In order to achieve the above object, a filter device according to an aspect of the present invention includes: a 1 st terminal and a 2 nd terminal; a 1 st filter circuit connected to the 1 st terminal and the 2 nd terminal, including a 1 st elastic wave resonator, and having a 1 st frequency band as a passband; and an additional circuit connected between the 1 st terminal and the 2 nd terminal in parallel with at least one of the 1 st elastic wave resonators, including a 2 nd elastic wave resonator, the additional circuit having an electromechanical coupling coefficient different from that of the 1 st filter circuit.
Effects of the invention
According to the present invention, it is possible to provide a small-sized filter device and a multiplexer having high attenuation characteristics corresponding to the bandwidth of an attenuation band.
Drawings
Fig. 1 is a circuit configuration diagram of a filter device, a multiplexer, and peripheral circuits according to an embodiment.
Fig. 2A is a schematic diagram schematically illustrating an example of an elastic wave resonator according to an embodiment.
Fig. 2B is a cross-sectional view schematically showing an elastic wave resonator according to
Fig. 3 is a schematic sectional view illustrating the
Fig. 4 is a schematic sectional view illustrating a 2 nd structure for adjusting an electromechanical coupling coefficient of an elastic wave resonator according to the embodiment.
Fig. 5 is a graph comparing the pass characteristics of the filter devices according to example 1 and comparative example 1 and the isolation characteristics of the multiplexer.
Fig. 6 is a graph comparing the pass characteristics of the filter devices according to example 2 and comparative example 2 and the isolation characteristics of the multiplexer.
Fig. 7A is a circuit configuration diagram of a multiplexer according to modification 2 of the embodiment.
Fig. 7B is a circuit configuration diagram of the multiplexer according to modification 3 of the embodiment.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to examples and drawings. The embodiments described below are all illustrative or specific examples. The numerical values, shapes, materials, constituent elements, arrangement of constituent elements, connection modes, and the like shown in the following embodiments are examples, and the gist thereof is not limited to the invention. Among the components in the following embodiments, components not described in the independent claims are described as arbitrary components. The sizes of the components shown in the drawings and the ratio of the sizes are not necessarily strict.
(embodiment mode)
[1 ] Circuit configurations of Filter device 40 and multiplexer 1 ]
Fig. 1 is a circuit configuration diagram of a filter device 40, a
The
The filter device 40 includes a
The terminal 130 is provided on a path connecting the common terminal 100 and the input/output terminal 110, and is provided on the common terminal 100 side of the common terminal 100 and the input/output terminal 110. The terminal 140 is provided on a path connecting the common terminal 100 and the input/output terminal 110, and is provided on the input/output terminal 110 side of the common terminal 100 and the input/output terminal 110. In addition, the terminals 130 and 140 may be nodes (contacts) connecting the wirings and the wirings.
The additional circuit 30 is a circuit that is connected to the terminals 130 and 140 (via the capacitor 31), includes the 2 nd elastic wave resonator, and generates a signal having an opposite phase with respect to a signal component of a predetermined frequency band other than the 1 st frequency band that passes through the
The term "cancel a high-frequency signal of a predetermined frequency band" is defined as that when a cancellation signal component generated by the additional circuit 30 and a signal component of a cancellation target (for example, a reception frequency band) in a signal transmitted through the
Here, the signal component to be canceled and the cancellation signal component are opposite phases, and the absolute value of the phase difference between the two is greater than 90 ° in the range of-180 ° to 180 °. This is equivalent to the signal component of the removal object and the removal signal having phase components in mutually opposite directions.
The cancellation signal preferably has the same amplitude as the signal component to be cancelled, but may have a different amplitude. When the amplitude of the addition result of the cancellation signal and the signal component to be cancelled becomes smaller than the amplitude of the original signal component to be cancelled, the attenuation characteristic of the filter device 40 can be improved.
The capacitor 31 is connected between the terminal 130 and the additional circuit 30. The capacitor 31 is configured to cancel the high-frequency signal of the predetermined frequency band passing through the
Here, in the filter device 40 according to the present embodiment, the electromechanical coupling coefficient K of the additional circuit 302 30Electromechanical coupling coefficient K with
In a conventional filter device having a configuration in which a filter circuit and an additional circuit are connected in parallel, when a frequency band having a bandwidth equal to or larger than a pass band of the filter circuit is attenuated in a wide range, for example, a configuration in which a plurality of additional circuits having different predetermined frequency bands are arranged is cited. However, in this case, the circuit of the filter device becomes large. On the other hand, when ensuring steepness at the end of the pass band of the filter circuit, a configuration in which a capacitor element is connected in parallel to a resonator in an additional circuit can be cited. However, in this case, there are problems such as an increase in size of the filter device due to the addition of the capacitor element and deterioration in the Q value of the filter device due to the conductance of the capacitor element.
In contrast, according to the above-described configuration of the filter device 40 according to the present embodiment, the electromechanical coupling coefficient K of the additional circuit 30 is set to be2 30And the electromechanical coupling coefficient K of the
The filter circuit 20 is a 2 nd filter circuit connected to the common terminal 100 and the input/output terminal 120, and having a 2 nd frequency band different from the 1 st frequency band as a pass band. The relationship between the frequency of the 1 st band and the frequency of the 2 nd band may be arbitrary.
According to the above configuration of the
In the present embodiment, the filter device 40 is a transmission filter that preferentially outputs the high-frequency signal of the 1 st frequency band among the high-frequency signals input from the input/output terminal 110, from the common terminal 100. The filter circuit 20 is a reception filter for preferentially outputting the high-frequency signal of the 2 nd frequency band among the high-frequency signals input from the common terminal 100 from the input/output terminal 120.
With this configuration, the
In the multiplexer according to the present invention, the filter device 40 and the filter circuit 20 may be a transmission filter or a reception filter. The number of filters connected to the common terminal 100 is not limited to two.
Further, an amplifier circuit for amplifying a high-frequency signal, a high-frequency signal processing circuit (RFIC), and the like are connected to the input/output terminals 110 and 120. The common terminal 100 need not be connected to the antenna 2, and may be connected to the antenna 2 via a switch circuit.
The matching inductor 3 is a circuit element connected between the antenna 2 and the common terminal 100 to obtain impedance matching between the antenna 2 and the
[2. basic Structure of elastic wave resonator ]
The basic structure of the elastic wave resonators constituting the
Fig. 2A is a schematic diagram schematically showing an example of an elastic wave resonator according to an embodiment, where (a) is a plan view and (b) and (c) are cross-sectional views at a one-dot chain line shown in (a). Fig. 2A illustrates a schematic plan view and a schematic cross-sectional view showing a basic structure of an elastic wave resonator constituting the
Elastic wave resonator 200 includes
As shown in fig. 2A (a), a pair of comb-shaped electrodes 201a and 201b are formed on the
Further, the
The adhesion layer 250a is a layer for improving adhesion between the
As a material of the main electrode layer 250b, for example, Al containing 1% Cu (copper) can be used. The film thickness of the main electrode layer 250b is, for example, 162 nm.
The
The materials constituting the adhesive layer 250A, the main electrode layer 250b, and the
Next, a laminated structure of the
As shown in fig. 2A (c), the
Piezoelectric film 253, for example, includes 50 ° Y-cut X-propagating LiTaO3A (lithium tantalate) piezoelectric single crystal or piezoelectric ceramic (a single crystal or ceramic of lithium tantalate cut on a surface whose normal is a plane rotated by 50 ° from the Y axis with the X axis as the center axis, and a single crystal or ceramic in which surface acoustic waves propagate in the X axis direction). As for the piezoelectric film 253, for example, the thickness is 600 nm. In addition, the material and cut angle of the piezoelectric single crystal used as the piezoelectric film 253 can be appropriately selected according to the required specifications of each filter.
The high acoustic velocity support substrate 251 is a substrate that supports the low acoustic velocity film 252, the piezoelectric film 253, and the
The low acoustic velocity film 252 is a film in which the acoustic velocity of the bulk wave in the low acoustic velocity film 252 is lower than the bulk wave propagating through the piezoelectric film 253, and is disposed between the piezoelectric film 253 and the high acoustic velocity support substrate 251. By this structure and the property that the energy of the elastic wave is concentrated in the medium having a low acoustic velocity, the leakage of the surface acoustic wave energy to the outside of the IDT electrode can be suppressed. The low acoustic velocity film 252 is a film mainly composed of, for example, silicon dioxide, and has a thickness of, for example, 670 nm.
Further, according to the above-described laminated structure of the
The high-acoustic-velocity support substrate 251 may have a structure in which a support substrate and a high-acoustic-velocity film are laminated, and the acoustic velocity of a bulk wave propagating through the high-acoustic-velocity film may be higher than that of an elastic wave such as a surface wave or a boundary wave propagating through the piezoelectric film 253. In this case, as the support substrate, a piezoelectric body such as lithium tantalate (lithium tantalate), lithium niobate (lithium niobate), quartz, or the like, various ceramics such as alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, or the like, a dielectric such as sapphire, glass, or a semiconductor such as silicon, gallium nitride, or the like, a resin substrate, or the like can be used. In addition, as the high sound velocity film, various high sound velocity materials such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, a DLC film, diamond, a medium containing the above materials as a main component, a medium containing a mixture of the above materials as a main component, and the like can be used.
Fig. 2B is a cross-sectional view schematically showing an elastic wave resonator according to
The piezoelectric film 253 and the piezoelectric single crystal substrate 61 can be appropriately changed in the lamination structure, material, cutting angle, and thickness by characteristics and the like according to the requirements of the
[3 ] Structure _ K for adjusting electromechanical coupling coefficient2 30>K2 10]
Next, the structure of the elastic wave resonator for adjusting the electromechanical coupling coefficient of the
The acoustic wave resonators constituting the
Fig. 3 is a schematic sectional view illustrating the
The 1 st elastic wave resonator constituting the
More specifically, as shown in fig. 3 (b), the 1 st elastic wave resonator has: a substrate 60 (1 st piezoelectric body), an IDT electrode 50 (1 st IDT electrode), and a
The
According to the above structure, the electromechanical coupling coefficient K of the additional circuit 302 30Becomes larger than the electromechanical coupling coefficient K of the
Further, both the 1 st elastic wave resonator constituting the
Even with this configuration, the electromechanical coupling coefficient K of the additional circuit 302 30Also becomes larger than the electromechanical coupling coefficient K of the
Further, the 1 st elastic wave resonator constituting the
More specifically, as shown in fig. 4 (b), the 1 st elastic wave resonator has: the piezoelectric substrate 60 (1 st piezoelectric body), the IDT electrode 50 (1 st IDT electrode), and a
Even with this configuration, the electromechanical coupling coefficient K of the additional circuit 302 30Also becomes larger than the electromechanical coupling coefficient K of the
Fig. 5 is a graph comparing the pass characteristics of the filter devices according to example 1 and comparative example 1 and the isolation characteristics of the multiplexer. Fig. 5 (a) shows the pass characteristic between the input-output terminal 110 of the filter device 40 and the common terminal 100. Fig. 5 (b) shows isolation characteristics between the input and output terminals 110 and 120 of the
In filter device 40 according to
The filter device according to comparative example 1 is different from the filter device 40 according to example 1 only in that the configuration of the 1 st elastic wave resonator included in the
In the present embodiment and the present comparative example, the 2 nd band is higher than the 1 st band, that is, the passband of the filter circuit 20 is higher than the passband of the
In
Further, in the examples1, the electromechanical coupling coefficient K of the additional circuit 302 30Greater than the electromechanical coupling coefficient K of the
That is, according to the filter device 40 according to
As shown in fig. 5 (b), the filter device 40 according to example 1 improves the isolation in the 2 nd band of the
That is, according to the
[4 ] Structure K for adjusting electromechanical coupling coefficient2 30<K2 10]
The 1 st elastic wave resonator constituting the
More specifically, as shown in fig. 3 (b), the 2 nd elastic wave resonator has: a substrate 60 (2 nd piezoelectric body), an IDT electrode 50 (2 nd IDT electrode), and a
According to the above structure, the electromechanical coupling coefficient K of the additional circuit 302 30Becomes smaller than the electromechanical coupling coefficient K of the
Further, both the 1 st elastic wave resonator constituting the
Even with this configuration, the electromechanical coupling coefficient K of the additional circuit 302 30Becomes smaller than the electromechanical coupling coefficient K of the
Further, the 1 st elastic wave resonator constituting the
More specifically, as shown in fig. 4 (b), the 2 nd elastic wave resonator has: the piezoelectric substrate 60 (2 nd piezoelectric body), the IDT electrode 50 (2 nd IDT electrode), and a
Even with such a configuration, the electromechanical coupling coefficient K of the additional circuit 302 30Becomes smaller than the electromechanical coupling coefficient K of the
Fig. 6 is a graph comparing the pass characteristics of the filter devices according to example 2 and comparative example 2 and the isolation characteristics of the multiplexer. Fig. 6 (a) shows the pass characteristic between the input-output terminal 110 of the filter device 40 and the common terminal 100. Fig. 6 (b) shows the isolation characteristic between the input/output terminals 110 and 120 of the
In filter device 40 according to embodiment 2, the configuration of the 1 st elastic wave resonator included in
The filter device according to comparative example 2 is different from the filter device 40 according to example 2 only in that the configuration of the 2 nd elastic wave resonator included in the additional circuit 30 is also the configuration shown in fig. 3 (a) in the same manner as the configuration of the 1 st elastic wave resonator included in the
In the present embodiment and the present comparative example, the 2 nd band is higher than the 1 st band, that is, the passband of the filter circuit 20 is higher than the passband of the
In example 2 and comparative example 2, the additional circuit 30 passes the high-frequency signal on the high-frequency side of the 1 st band in a phase substantially opposite to the phase of the high-frequency signal on the high-frequency side passed through the
Further, in embodiment 2, the electromechanical coupling of the circuit 30 is addedSum coefficient K2 30Smaller than the electromechanical coupling coefficient K of the
That is, according to the filter device 40 according to embodiment 2, the electromechanical coupling coefficient K of the additional circuit 302 30Smaller than the electromechanical coupling coefficient K of the
As shown in fig. 6 (b), the filter device 40 according to example 2 improves the isolation in the 2 nd band of the
That is, according to the
In
In
In order to adjust the electromechanical coupling coefficient, as shown in fig. 3 and 4, the dielectric layers formed on the substrate and the IDT electrodes are formed or the thicknesses of the dielectric layers are different from each other. These structures can be realized by etching a portion on the substrate in the manufacturing process by using the same substrate, and thus the electrode layout area of the filter device 40 can be reduced by a simplified process. This can reduce the size of the filter device 40 and the
[5. modified example of multiplexer ]
Fig. 7A is a circuit configuration diagram of the multiplexer 1A according to modification 2 of the embodiment. As shown in the drawing, the multiplexer 1A according to the present modification includes a filter device 40, a filter circuit 20, a common terminal 100, and input/output terminals 110 and 120. The multiplexer 1A according to the present modification has the same circuit configuration as the
In addition, the electromechanical coupling coefficient K of the additional circuit 302 30Smaller than the electromechanical coupling coefficient K of the
In the case of the above configuration, the filter connected to the common terminal 100 is only the filter circuit 20 except the filter device 40. Therefore, in many cases, the frequency band in which high attenuation is required in the filter device 40 is (part of) the pass band of the filter circuit 20.
Thus, in such a case, it is only necessary to provide the filter device with40, so that the narrow band is attenuated, the electromechanical coupling coefficient K of the additional circuit 302 30Set to be smaller than the electromechanical coupling coefficient K of the
Fig. 7B is a circuit configuration diagram of the multiplexer 1B according to modification 3 of the embodiment. As shown in the drawing, the multiplexer 1B according to the present modification includes a filter device 40, filter circuits 20A and 20B, a common terminal 100, and input/output terminals 110, 120A, and 120B. The multiplexer 1B according to this modification is different from the multiplexer 1A according to modification 2 in that a 3 rd filter circuit 20B is added.
In addition, the electromechanical coupling coefficient K of the additional circuit 302 30Greater than the electromechanical coupling coefficient K of the
The filter circuit 20A is a 2 nd filter circuit connected to the common terminal 100 and the input/output terminal 120A, and having a 2 nd frequency band different from the 1 st frequency band as a pass band.
The filter circuit 20B is a 3 rd filter circuit connected to the common terminal 100 and the input/output terminal 120B, and has a 3 rd frequency band different from the 1 st frequency band and the 2 nd frequency band and located between the 1 st frequency band and the 2 nd frequency band as a pass band.
In the case of the above configuration, the filters connected to the common terminal 100, except for the filter device 40, are two filter circuits 20A and 20B. The pass band of filter device 40 is not located between the pass band of filter circuit 20A and the pass band of filter circuit 20B, and the pass band of filter circuit 20A and the pass band of filter circuit 20B are located on the higher frequency side or the lower frequency side than the pass band of filter device 40. Therefore, in many cases, the frequency band in which high attenuation is required in the filter device 40 is a wide band including the pass band of the filter circuit 20A and the pass band of the filter circuit 20B.
Therefore, in such a case, since it is necessary to attenuate a wide band in the filter device 40, the electromechanical coupling coefficient K of the additional circuit 30 is set to be2 30Set to be greater than the electromechanical coupling coefficient K of the
According to the multiplexers according to modification 2 and modification 3, it is possible to provide a small-sized filter device and multiplexer having high attenuation characteristics corresponding to the bandwidth of the attenuation band.
(other embodiments)
Although the filter device and the multiplexer according to the present invention have been described above with reference to the embodiments, the filter device and the multiplexer according to the present invention are not limited to the embodiments. Other embodiments in which arbitrary constituent elements in the above-described embodiments are combined, modified examples in which various modifications that may occur to those skilled in the art are applied to the above-described embodiments and the modified examples thereof within a range that does not depart from the gist of the present invention, and various devices in which the filter device and the multiplexer of the present invention are incorporated are also included in the present invention.
In the above embodiment, the phrase "the electromechanical coupling coefficient of a is different from the electromechanical coupling coefficient of B", and excluding that the electromechanical coupling coefficient of a is substantially the same as the electromechanical coupling coefficient of B means that the relative bandwidths (%) of a and B differ by 0.5 point or more.
In the above-described embodiments, the electromechanical coupling coefficient is a parameter indicating the efficiency of interconversion between mechanical energy and electrical energy between the piezoelectric substrate and the IDT electrode formed thereon in the surface acoustic wave device. Therefore, when the electrical characteristics of the surface acoustic wave device are adjusted by circuit elements externally added to the surface acoustic wave device, it is defined that the electromechanical coupling coefficient is not adjusted.
In the filter device and the multiplexer according to the embodiment, an inductor and a capacitor may be connected between the respective components. The inductor may include a wiring inductor formed of a wiring connecting the respective components.
Industrial applicability
The present invention is widely applicable to communication devices such as cellular phones as a low-loss and high-attenuation filter applicable to a frequency standard with multiple frequency bands and a low-loss and high-isolation multiplexer.
Description of the reference numerals
1. 1A, 1B: a multiplexer;
2: an antenna;
3: an inductor for matching;
10. 20, 20A, 20B: a filter circuit;
30: an additional circuit;
31: a capacitor;
31a, 31 b: a surface acoustic wave resonator;
40: a filter means;
50: an IDT electrode;
60: a substrate;
61: a piezoelectric single crystal substrate;
70A, 70B: a dielectric layer;
100: a common terminal;
110. 120, 120A, 120B: an input/output terminal;
130. 140: a terminal;
200: an elastic wave resonator;
200a, 200 b: an electrode finger;
201a, 201 b: a comb-shaped electrode;
202a, 202 b: a bus bar electrode;
250 a: a sealing layer;
250b, and (3): a main electrode layer;
251: a high acoustic velocity support substrate;
252: a low acoustic velocity membrane;
253: a piezoelectric film.
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