WO2023021949A1 - Elastic wave filter device and complex filter device - Google Patents

Elastic wave filter device and complex filter device Download PDF

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Publication number
WO2023021949A1
WO2023021949A1 PCT/JP2022/028890 JP2022028890W WO2023021949A1 WO 2023021949 A1 WO2023021949 A1 WO 2023021949A1 JP 2022028890 W JP2022028890 W JP 2022028890W WO 2023021949 A1 WO2023021949 A1 WO 2023021949A1
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electrode
elastic wave
wave filter
filter device
comb
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PCT/JP2022/028890
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French (fr)
Japanese (ja)
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普一 中村
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株式会社村田製作所
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Priority to CN202280056241.0A priority Critical patent/CN117837085A/en
Publication of WO2023021949A1 publication Critical patent/WO2023021949A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/72—Networks using surface acoustic waves

Definitions

  • the present invention relates to an elastic wave filter device and a composite filter device having a plurality of cascaded longitudinally coupled resonator type elastic wave filters.
  • Patent Document 1 discloses a band-pass filter having a longitudinally coupled resonator type elastic wave filter.
  • the second longitudinally coupled resonator-type elastic wave filter is cascade-connected to the first longitudinally coupled resonator-type elastic wave filter.
  • a configuration in which a plurality of longitudinally coupled resonator-type elastic wave filters are cascaded can increase the amount of attenuation outside the passband.
  • a plurality of longitudinally-coupled resonator-type elastic wave filters are connected in multiple stages, there is a problem that the loss in the passband becomes worse. Therefore, it has been difficult to achieve both expansion of out-of-band attenuation and reduction of insertion loss.
  • An object of the present invention is to provide an elastic wave filter device and a composite filter device having the elastic wave filter device, which can achieve both improvement of filter characteristics such as out-of-band attenuation and reduction of insertion loss.
  • An acoustic wave filter device includes a piezoelectric substrate and a band-pass filter formed on the piezoelectric substrate, wherein the band-pass filter includes first and second longitudinal couplings having a plurality of IDT electrodes.
  • a resonator-type elastic wave filter wherein the second longitudinally-coupled resonator-type elastic wave filter is cascade-connected to the first longitudinally-coupled resonator-type elastic wave filter; a first ground electrode; and a second ground electrode provided on the piezoelectric substrate and not electrically connected to the first ground electrode on the piezoelectric substrate;
  • the central IDT electrode among the plurality of IDT electrodes is connected to a signal potential.
  • a third comb tooth electrode is connected to the second ground electrode.
  • a composite filter device comprises an elastic wave filter device configured according to the present invention and at least one other band-pass filter having one end commonly connected to the elastic wave filter device.
  • an elastic wave filter device and a composite filter device having the elastic wave filter device which can achieve both improvement of filter characteristics such as out-of-band attenuation and reduction of insertion loss.
  • FIG. 1 is a schematic circuit diagram showing an electrode structure of an elastic wave filter device according to a first embodiment of the invention.
  • FIG. 2 is a schematic plan view of a composite filter device having an acoustic wave filter device according to the first embodiment of the invention.
  • FIG. 3 is a diagram showing attenuation-frequency characteristics of the acoustic wave filter devices of the example and the comparative example.
  • FIG. 4 is a diagram showing the attenuation-frequency characteristics of the acoustic wave filter devices of the embodiment and the comparative example, and is a diagram showing the attenuation-frequency characteristics shown by enlarging the scale of the attenuation in FIG. FIG.
  • FIG. 5 is a diagram showing isolation characteristics from the transmission filter side to the reception filter side in the elastic wave filter devices of the embodiment and the comparative example.
  • FIG. 6 is an enlarged view showing isolation characteristics from the transmission filter side to the reception filter side in the elastic wave filter devices of the embodiment and the comparative example.
  • FIG. 7 is a schematic circuit diagram for explaining a multiplexer as an example of a composite filter device as a second embodiment of the invention.
  • FIG. 8 is a schematic front cross-sectional view for explaining an elastic wave filter device according to a third embodiment of the invention.
  • FIG. 9 is a schematic front cross-sectional view for explaining an elastic wave filter device according to a fourth embodiment of the invention.
  • FIG. 10 is a front cross-sectional view of an elastic wave filter device according to a fifth embodiment of the invention.
  • FIG. 11 is a front cross-sectional view of an elastic wave filter device for explaining a modification of the first embodiment.
  • FIG. 1 is a schematic circuit diagram showing an electrode structure of an elastic wave filter device according to a first embodiment of the invention
  • FIG. 2 is a composite filter device having the elastic wave filter device according to the first embodiment. is a schematic plan view of the.
  • the composite filter device 4 has a piezoelectric substrate 3 as shown in FIG.
  • the piezoelectric substrate 3 is a substrate made of piezoelectric single crystal.
  • the illustrated electrode structure is provided on the piezoelectric substrate 3.
  • the first band-pass filter 1 which is the elastic wave filter device of the first embodiment, and the second band-pass filter A filter 2 is provided.
  • a first band-pass filter 1 is a reception filter.
  • the second bandpass filter 2 is a transmission filter.
  • the first band-pass filter 1 includes a first longitudinally coupled resonator-type elastic wave filter 11 and a second longitudinally coupled resonator-type elastic wave filter 11 cascade-connected to the first longitudinally coupled resonator-type elastic wave filter 11. and a wave filter 12 .
  • the first band-pass filter 1 includes at least one longitudinally coupled resonator connected in series with the second longitudinally coupled resonator-type elastic wave filter 12 or the first longitudinally coupled resonator-type elastic wave filter 11. It may further have a type acoustic wave filter.
  • the first longitudinally coupled resonator-type elastic wave filter 11 and the second longitudinally coupled resonator-type elastic wave filter 12 each have a plurality of first to fifth IDT electrodes 11a to 11e and 12a to 12e.
  • the first and second 5-IDT longitudinally coupled resonator type elastic wave filters 11 and 12 are used, but the number of IDTs in the longitudinally coupled resonator type elastic wave filter is 3, 7, or the like. may be other numbers.
  • first longitudinally coupled resonator-type elastic wave filter 11 reflectors 11f and 11g are provided on both sides of the area in which the first to fifth IDT electrodes 11a to 11e are provided in the elastic wave propagation direction.
  • reflectors 12f and 12g are provided on both sides of the area in which the first to fifth IDT electrodes 12a to 12e are provided in the elastic wave propagation direction. It is
  • an electrode 9 serving as an antenna terminal is provided on the first main surface 3 a of the piezoelectric substrate 3 .
  • An input electrode 5 is connected to this electrode 9 .
  • a first band-pass filter 1 is connected to the input electrode 5 .
  • a second band-pass filter 2 is also connected to the electrode 9 .
  • a composite filter device 4 is a duplexer having a first band-pass filter 1 and a second band-pass filter 2 .
  • the input electrode 5 is connected to the first ends of the second and fourth IDT electrodes 11b and 11d. Second ends of the second and fourth IDT electrodes 11 b and 11 d are connected to the second ground electrode 8 .
  • First and second ground electrodes 7 and 8 are provided on the first main surface 3a.
  • a signal electrode 6 as a receiving terminal is provided on the first main surface 3a.
  • the second band-pass filter 2 is connected to a transmission electrode 10a provided on the first main surface 3a and a ground electrode 10b.
  • the first ends of the first, third and fifth IDT electrodes 11a, 11c and 11e are connected to the first ground electrode 7 or the second ground electrode 8.
  • the second ends of the first, third and fifth IDT electrodes 11a, 11c and 11e are the first IDT electrode 12a and the third IDT electrode 12a of the second longitudinally coupled resonator type elastic wave filter 12, respectively. It is connected to the first ends of the electrode 12c and the fifth IDT electrode 12e.
  • the second end of the first IDT electrode 12 a is connected to the first ground electrode 7 .
  • a second end of the fifth IDT electrode 12 e is connected to the second ground electrode 8 .
  • the third IDT electrode 12c has a first comb-shaped electrode 12c1 and second and third comb-shaped electrodes 12c2 and 12c3.
  • the first comb-shaped electrode 12c1 is an input-side comb-shaped electrode
  • the second and third comb-shaped electrodes 12c2 and 12c3 are ground-side comb-shaped electrodes.
  • the second and third comb-teeth electrodes 12c2 and 12c3 correspond to a configuration in which the ground-side comb-teeth electrode is divided into two.
  • the ground-side comb-teeth electrode of the third IDT electrode 12c may be divided into three or more. That is, the third IDT electrode 12c may further have at least one other comb-teeth electrode connected to the ground potential in addition to the second and third comb-teeth electrodes 12c2 and 12c3.
  • the first comb-teeth electrode 12 c 1 is connected to the third IDT electrode 11 c of the first band-pass filter 1 .
  • the second comb-teeth electrode 12c2 is connected to the first ground electrode 7.
  • the third comb-teeth electrode 12c3 is connected to the second ground electrode 8. As shown in FIG.
  • first ground electrode 7 and the second ground electrode 8 are finally connected to the ground potential.
  • the first ground electrode 7 and the second ground electrode 8 are not electrically connected.
  • a first ground electrode 7 and a second ground electrode 8 are provided on the first main surface 3a.
  • the first ground electrode 7 and the second ground electrode 8 may be provided on the second main surface 3b side of the piezoelectric substrate 3, as shown in FIG.
  • the electrical connection between the first ground electrode 7 and the second comb-teeth electrode 12c2 and the electrical connection between the second ground electrode 8 and the third comb-teeth electrode 12c3 are made through the through-hole electrodes 61 and 62. and so on.
  • the first ends of the second and fourth IDT electrodes 12b and 12d are commonly connected and electrically connected to the first ground electrode 7. Second ends of the second and fourth IDT electrodes 12 b and 12 d are connected in common and connected to the signal electrode 6 .
  • a feature of the first bandpass filter 1 is that, as described above, in the second longitudinally coupled resonator type elastic wave filter 12, the third IDT electrode 12c located in the center , the second comb-teeth electrode 12c2 is connected to the first ground electrode 7, and the third comb-teeth electrode 12c3 is connected to the second ground electrode 8.
  • FIG. 3 shows attenuation-frequency characteristics of an example of the first band-pass filter 1 and an acoustic wave filter device of a comparative example.
  • FIG. 4 is a diagram showing attenuation-frequency characteristics showing an enlarged main part of FIG. 3 and 4, the solid line indicates the results of the example, and the dashed line indicates the results of the comparative example.
  • the band-pass filters of the examples and comparative examples are reception filters of Band 12 for mobile communication.
  • the pass band of the reception filter of Band 12 is 729 MHz to 746 MHz.
  • the position of 729 MHz, which is the lower limit of the passband of the reception filter of Band 12 is indicated by M3.
  • the position of the upper limit of 746 MHz is indicated by M4.
  • the passband of the transmission filter of Band 12 is from 699 MHz to 716 MHz.
  • the position of the lower limit of 699 MHz is indicated by M1
  • the position of the upper limit of 716 MHz is indicated by M2.
  • the first band-pass filter 1 is a Band 12 reception filter. Therefore, in order to improve the out-of-band attenuation, it is required that the attenuation in the passband of the transmission filter, 699 MHz to 716 MHz, is large. Here, as for the attenuation amount, it is required that the portion with the smallest attenuation amount in the passband of the transmission filter of Band 12 is larger. As shown by the arrow A in FIG. 4, according to the elastic wave filter device of the embodiment, the attenuation at the portion where the attenuation is the smallest near 715 MHz is increased compared to the elastic wave filter device of the comparative example. I understand. That is, in the elastic wave filter device of the embodiment, it is possible to improve the out-of-band attenuation amount compared to the elastic wave filter device of the comparative example.
  • FIG. 5 is a diagram showing the isolation characteristics from the transmission filter side to the reception filter side in the embodiment and the comparative example
  • FIG. 6 is a diagram showing the isolation characteristics by enlarging the main part of FIG. be.
  • the isolation characteristics as shown by the arrow B in FIG. 6, it is possible to improve the isolation in the embodiment compared to the comparative example in the vicinity of 715 MHz.
  • the reason why the out-of-band attenuation amount can be improved in the embodiment as described above is as follows. That is, in the third IDT electrode 12c, the comb-teeth electrode on the side connected to the ground potential is divided into first and second comb-shaped electrodes provided on the piezoelectric substrate 3 and not electrically connected to each other. 2 ground electrodes 7 and 8. Therefore, it is considered that the out-of-band attenuation is increased due to the difference between the ground by the first ground electrode 7 and the ground by the second ground electrode 8 compared to the comparative example.
  • the inductance L and the capacitance C differ between the circuit extending from the second comb-teeth electrode 12c2 to the ground potential and the circuit extending from the third comb-teeth electrode 12c3 to the ground potential. Therefore, the strength of the ground connected to the second and third comb-teeth electrodes 12c2 and 12c3 is generated. As a result, the frequency position of the attenuation pole is changed, and it is considered that the out-of-band attenuation amount is expanded as described above.
  • the first band-pass filter 1 of the present embodiment it is possible to improve the out-of-band attenuation amount, that is, the attenuation amount in the transmission band of the reception filter, without deteriorating the insertion loss. 4 can be improved.
  • the third IDT electrode 12c is connected to the first to It has third comb-teeth electrodes 12c1 to 12c3.
  • the central IDT electrode among the plurality of IDT electrodes has the first to third comb-teeth electrodes.
  • the central IDT electrode among the plurality of IDT electrodes has the first to third comb-teeth electrodes.
  • the first comb-shaped electrode is connected to the signal potential
  • the second comb-shaped electrode is connected to the first ground electrode 7
  • the third comb-shaped electrode is connected to the second ground electrode 8. It should be connected.
  • FIG. 7 is a schematic circuit diagram of a composite filter device 21 as a second embodiment of the invention.
  • Composite filter device 21 is a multiplexer.
  • at least one further bandpass filter 22 is also connected.
  • it may further include at least one band-pass filter 22 having one end connected in common.
  • FIG. 8 is a schematic front cross-sectional view of an elastic wave filter device 31 according to a third embodiment of the invention.
  • the piezoelectric substrate has piezoelectric layer 36 , support substrate 32 , and intermediate layer 33 laminated between piezoelectric layer 36 and support substrate 32 .
  • the piezoelectric substrate may be a composite substrate in which other layers are laminated on the piezoelectric layer 36 .
  • an IDT electrode 37 is provided on the piezoelectric layer 36.
  • the intermediate layer 33 has a high acoustic velocity film 34 and a low acoustic velocity film 35 .
  • the high acoustic velocity film 34 is made of a high acoustic velocity material.
  • a high acoustic velocity material is a material in which the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave propagating through the piezoelectric layer 36 .
  • Such high sonic materials include aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, fort.
  • Various materials such as stellite, magnesia, a DLC (diamond-like carbon) film or diamond, a medium containing the above materials as a main component, and a medium containing a mixture of the above materials as a main component can be used.
  • the low sound velocity film 35 is made of a low sound velocity material.
  • a low sound velocity material is a material in which a propagating bulk wave has a lower acoustic velocity than a bulk wave propagating through the piezoelectric layer 36 .
  • Such low sound velocity materials include silicon oxide, glass, silicon oxynitride, tantalum oxide, compounds obtained by adding fluorine, carbon, boron, hydrogen, or silanol groups to silicon oxide, and media containing the above materials as main components. etc. can be used.
  • the support substrate 32 is made of a semiconductor material such as silicon or an insulating material such as alumina.
  • the low acoustic velocity film 35 may be omitted, or the high acoustic velocity membrane 34 and the support substrate 32 may be integrated with the same high acoustic velocity material. That is, instead of the structure in which the supporting substrate 32 and the high acoustic velocity film 34 are laminated, a supporting substrate made of a high acoustic velocity material may be used.
  • FIG. 9 is a schematic front cross-sectional view of an elastic wave filter device according to a fourth embodiment.
  • an IDT electrode 47 is provided on the piezoelectric layer 46 .
  • An intermediate layer 43 is provided between the support substrate 42 and the piezoelectric layer 46 .
  • the intermediate layer 43 has a structure in which high acoustic impedance layers 43a, 43c, 43e with relatively high acoustic impedance and low acoustic impedance layers 43b, 43d, 43f with relatively low acoustic impedance are alternately laminated.
  • An intermediate layer 43 made of such an acoustic reflection layer may be used.
  • FIG. 10 is a front cross-sectional view of an elastic wave filter device according to a fifth embodiment of the invention.
  • the support substrate 52 is provided with a recess 52a. This concave portion 52a constitutes a cavity 52b.
  • the piezoelectric layer 46 is laminated on the support substrate 52 via the bonding layer 53 so as to cover the cavity 52b.
  • the present invention can also be applied to the elastic wave filter device 51 having such a cavity 52b.

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  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

An elastic wave filter device is provided that achieves both improvement in filter characteristics, such as the amount of out-of-band attenuation, and reduction of insertion loss.　A bandpass filter 1 is constructed on a piezoelectric substrate 3. The bandpass filter 1 includes first and second vertically coupled resonator-type elastic wave filters 11, 12. A second vertically coupled resonator-type elastic wave filter 12 is vertically connected to a first vertically coupled resonator-type elastic wave filter 11. A first ground electrode 7 and a second ground electrode 8 are provided on the piezoelectric substrate 3. The first ground electrode 7 and the second ground electrode 8 are not electrically connected on the piezoelectric substrate 3. In at least one of the first and second vertically coupled resonator-type elastic wave filters 11, 12, an IDT electrode 12c positioned at the center of a plurality of IDT electrodes includes a first interdigitated electrode 12c1 connected to a signal potential, and second and third interdigitated electrodes 12c2, 12c3 connected to a ground potential. The second interdigitated electrode 12c2 is connected to the first ground electrode 7. The third interdigitated electrode 12c3 is connected to the second ground electrode 8.

Description

弾性波フィルタ装置及び複合フィルタ装置Elastic wave filter device and composite filter device
　本発明は、縦続接続された複数の縦結合共振子型弾性波フィルタを有する、弾性波フィルタ装置及び複合フィルタ装置に関する。 The present invention relates to an elastic wave filter device and a composite filter device having a plurality of cascaded longitudinally coupled resonator type elastic wave filters.
　下記の特許文献１には、縦結合共振子型弾性波フィルタを有する帯域通過型フィルタが開示されている。ここでは、第１の縦結合共振子型弾性波フィルタに、第２の縦結合共振子型弾性波フィルタが縦続接続されている。 Patent Document 1 below discloses a band-pass filter having a longitudinally coupled resonator type elastic wave filter. Here, the second longitudinally coupled resonator-type elastic wave filter is cascade-connected to the first longitudinally coupled resonator-type elastic wave filter.
特開平９－１３０２０３号公報JP-A-9-130203
　複数の縦結合共振子型弾性波フィルタが縦続接続されている構成では、通過帯域外の減衰量を大きくすることができる。しかしながら、複数の縦結合共振子型弾性波フィルタを多段縦続接続すると、通過帯域における損失が悪化するという問題があった。よって、帯域外減衰量の拡大と挿入損失の低減とを両立することが困難であった。 A configuration in which a plurality of longitudinally coupled resonator-type elastic wave filters are cascaded can increase the amount of attenuation outside the passband. However, when a plurality of longitudinally-coupled resonator-type elastic wave filters are connected in multiple stages, there is a problem that the loss in the passband becomes worse. Therefore, it has been difficult to achieve both expansion of out-of-band attenuation and reduction of insertion loss.
　本発明の目的は、帯域外減衰量などのフィルタ特性の改善と、挿入損失の低減とを両立し得る、弾性波フィルタ装置及び該弾性波フィルタ装置を有する複合フィルタ装置を提供することにある。 An object of the present invention is to provide an elastic wave filter device and a composite filter device having the elastic wave filter device, which can achieve both improvement of filter characteristics such as out-of-band attenuation and reduction of insertion loss.
　本発明に係る弾性波フィルタ装置は、圧電基板と、前記圧電基板に構成された帯域通過型フィルタとを備え、前記帯域通過型フィルタが、複数のＩＤＴ電極を有する第１，第２の縦結合共振子型弾性波フィルタを有し、前記第１の縦結合共振子型弾性波フィルタに、前記第２の縦結合共振子型弾性波フィルタが縦続接続されており、前記圧電基板に設けられた第１のグラウンド電極と、前記圧電基板に設けられており、前記第１のグラウンド電極と前記圧電基板において電気的に接続されていない、第２のグラウンド電極とを有し、前記第１の縦結合共振子型弾性波フィルタ及び前記第２の縦結合共振子型弾性波フィルタのうちの少なくとも一方において、前記複数のＩＤＴ電極のうち中央に位置しているＩＤＴ電極が、信号電位に接続される第１の櫛歯電極と、グラウンド電位に接続される第２及び第３の櫛歯電極とを有し、前記第２の櫛歯電極が、前記第１のグラウンド電極に接続されており、前記第３の櫛歯電極が、前記第２のグラウンド電極に接続されている。 An acoustic wave filter device according to the present invention includes a piezoelectric substrate and a band-pass filter formed on the piezoelectric substrate, wherein the band-pass filter includes first and second longitudinal couplings having a plurality of IDT electrodes. a resonator-type elastic wave filter, wherein the second longitudinally-coupled resonator-type elastic wave filter is cascade-connected to the first longitudinally-coupled resonator-type elastic wave filter; a first ground electrode; and a second ground electrode provided on the piezoelectric substrate and not electrically connected to the first ground electrode on the piezoelectric substrate; In at least one of the coupled resonator-type elastic wave filter and the second longitudinally coupled resonator-type elastic wave filter, the central IDT electrode among the plurality of IDT electrodes is connected to a signal potential. a first comb-teeth electrode and second and third comb-teeth electrodes connected to a ground potential, wherein the second comb-teeth electrode is connected to the first ground electrode; A third comb tooth electrode is connected to the second ground electrode.
　本発明に係る複合フィルタ装置は、本発明に従って構成された弾性波フィルタ装置と、該弾性波フィルタ装置に一端が共通接続された少なくとも１つの他の帯域通過型フィルタとを備える。 A composite filter device according to the present invention comprises an elastic wave filter device configured according to the present invention and at least one other band-pass filter having one end commonly connected to the elastic wave filter device.
　本発明によれば、帯域外減衰量などのフィルタ特性の改善と、挿入損失の低減とを両立し得る、弾性波フィルタ装置及び該弾性波フィルタ装置を有する複合フィルタ装置を提供することができる。 According to the present invention, it is possible to provide an elastic wave filter device and a composite filter device having the elastic wave filter device, which can achieve both improvement of filter characteristics such as out-of-band attenuation and reduction of insertion loss.
図１は、本発明の第１の実施形態に係る弾性波フィルタ装置の電極構造を示す略図的回路図である。FIG. 1 is a schematic circuit diagram showing an electrode structure of an elastic wave filter device according to a first embodiment of the invention. 図２は、本発明の第１の実施形態に係る弾性波フィルタ装置を有する複合フィルタ装置の略図的平面図である。FIG. 2 is a schematic plan view of a composite filter device having an acoustic wave filter device according to the first embodiment of the invention. 図３は、実施例及び比較例の弾性波フィルタ装置の減衰量－周波数特性を示す図である。FIG. 3 is a diagram showing attenuation-frequency characteristics of the acoustic wave filter devices of the example and the comparative example. 図４は、実施例及び比較例の弾性波フィルタ装置の減衰量－周波数特性を示す図であり、図３の減衰量のスケールを拡大して示す減衰量－周波数特性を示す図である。FIG. 4 is a diagram showing the attenuation-frequency characteristics of the acoustic wave filter devices of the embodiment and the comparative example, and is a diagram showing the attenuation-frequency characteristics shown by enlarging the scale of the attenuation in FIG. 図５は、実施例及び比較例の弾性波フィルタ装置における送信フィルタ側から受信フィルタ側へのアイソレーション特性を示す図である。FIG. 5 is a diagram showing isolation characteristics from the transmission filter side to the reception filter side in the elastic wave filter devices of the embodiment and the comparative example. 図６は、実施例及び比較例の弾性波フィルタ装置における送信フィルタ側から受信フィルタ側へのアイソレーション特性を示す拡大図である。FIG. 6 is an enlarged view showing isolation characteristics from the transmission filter side to the reception filter side in the elastic wave filter devices of the embodiment and the comparative example. 図７は、本発明の第２の実施形態としての複合フィルタ装置の一例としてのマルチプレクサを説明するための略図的回路図である。FIG. 7 is a schematic circuit diagram for explaining a multiplexer as an example of a composite filter device as a second embodiment of the invention. 図８は、本発明の第３の実施形態に係る弾性波フィルタ装置を説明するための略図的正面断面図である。FIG. 8 is a schematic front cross-sectional view for explaining an elastic wave filter device according to a third embodiment of the invention. 図９は、本発明の第４の実施形態に係る弾性波フィルタ装置を説明するための略図的正面断面図である。FIG. 9 is a schematic front cross-sectional view for explaining an elastic wave filter device according to a fourth embodiment of the invention. 図１０は、本発明の第５の実施形態に係る弾性波フィルタ装置の正面断面図である。FIG. 10 is a front cross-sectional view of an elastic wave filter device according to a fifth embodiment of the invention. 図１１は、第１の実施形態の変形例を説明するための弾性波フィルタ装置の正面断面図である。FIG. 11 is a front cross-sectional view of an elastic wave filter device for explaining a modification of the first embodiment.
　以下、図面を参照しつつ、本発明の具体的な実施形態を説明することにより、本発明を明らかにする。 Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.
　なお、本明細書に記載の各実施形態は、例示的なものであり、異なる実施形態間において、構成の部分的な置換または組み合わせが可能であることを指摘しておく。 It should be noted that each embodiment described in this specification is an example, and partial replacement or combination of configurations is possible between different embodiments.
　図１は、本発明の第１の実施形態に係る弾性波フィルタ装置の電極構造を示す略図的回路図であり、図２は、第１の実施形態に係る弾性波フィルタ装置を有する複合フィルタ装置の略図的平面図である。 FIG. 1 is a schematic circuit diagram showing an electrode structure of an elastic wave filter device according to a first embodiment of the invention, and FIG. 2 is a composite filter device having the elastic wave filter device according to the first embodiment. is a schematic plan view of the.
　図２に示すように、複合フィルタ装置４は圧電基板３を有する。圧電基板３は圧電単結晶からなる基板である。複合フィルタ装置４では、圧電基板３上に、図示の電極構造が設けられている。圧電基板３の第１の主面３ａ上に、図示の電極構造を設けることにより、第１の実施形態の弾性波フィルタ装置である第１の帯域通過型フィルタ１と、第２の帯域通過型フィルタ２とが設けられている。第１の帯域通過型フィルタ１は受信フィルタである。第２の帯域通過型フィルタ２は送信フィルタである。 The composite filter device 4 has a piezoelectric substrate 3 as shown in FIG. The piezoelectric substrate 3 is a substrate made of piezoelectric single crystal. In the composite filter device 4, the illustrated electrode structure is provided on the piezoelectric substrate 3. As shown in FIG. By providing the illustrated electrode structure on the first main surface 3a of the piezoelectric substrate 3, the first band-pass filter 1, which is the elastic wave filter device of the first embodiment, and the second band-pass filter A filter 2 is provided. A first band-pass filter 1 is a reception filter. The second bandpass filter 2 is a transmission filter.
　第１の帯域通過型フィルタ１は、第１の縦結合共振子型弾性波フィルタ１１と、第１の縦結合共振子型弾性波フィルタ１１に縦続接続された第２の縦結合共振子型弾性波フィルタ１２とを有する。なお、第１の帯域通過型フィルタ１は、第２の縦結合共振子型弾性波フィルタ１２または第１の縦結合共振子型弾性波フィルタ１１に縦続接続された、少なくとも１つの縦結合共振子型弾性波フィルタをさらに有していてもよい。 The first band-pass filter 1 includes a first longitudinally coupled resonator-type elastic wave filter 11 and a second longitudinally coupled resonator-type elastic wave filter 11 cascade-connected to the first longitudinally coupled resonator-type elastic wave filter 11. and a wave filter 12 . The first band-pass filter 1 includes at least one longitudinally coupled resonator connected in series with the second longitudinally coupled resonator-type elastic wave filter 12 or the first longitudinally coupled resonator-type elastic wave filter 11. It may further have a type acoustic wave filter.
　第１の縦結合共振子型弾性波フィルタ１１及び第２の縦結合共振子型弾性波フィルタ１２は、それぞれ、複数の第１～第５のＩＤＴ電極１１ａ～１１ｅ，１２ａ～１２ｅを有する。なお、本実施形態では、５ＩＤＴ型の第１，第２の縦結合共振子型弾性波フィルタ１１，１２を用いているが、縦結合共振子型弾性波フィルタにおけるＩＤＴの数は３あるいは７などの他の数であってもよい。 The first longitudinally coupled resonator-type elastic wave filter 11 and the second longitudinally coupled resonator-type elastic wave filter 12 each have a plurality of first to fifth IDT electrodes 11a to 11e and 12a to 12e. In this embodiment, the first and second 5-IDT longitudinally coupled resonator type elastic wave filters 11 and 12 are used, but the number of IDTs in the longitudinally coupled resonator type elastic wave filter is 3, 7, or the like. may be other numbers.
　第１の縦結合共振子型弾性波フィルタ１１では、第１～第５のＩＤＴ電極１１ａ～１１ｅが設けられている領域の弾性波伝搬方向両側に、反射器１１ｆ，１１ｇが設けられている。同様に、第２の縦結合共振子型弾性波フィルタ１２においても、第１～第５のＩＤＴ電極１２ａ～１２ｅが設けられている領域の弾性波伝搬方向両側に、反射器１２ｆ，１２ｇが設けられている。 In the first longitudinally coupled resonator-type elastic wave filter 11, reflectors 11f and 11g are provided on both sides of the area in which the first to fifth IDT electrodes 11a to 11e are provided in the elastic wave propagation direction. Similarly, in the second longitudinally coupled resonator-type elastic wave filter 12, reflectors 12f and 12g are provided on both sides of the area in which the first to fifth IDT electrodes 12a to 12e are provided in the elastic wave propagation direction. It is
　複合フィルタ装置４では、圧電基板３の第１の主面３ａ上に、アンテナ端子となる電極９が設けられている。この電極９に、入力電極５が接続されている。入力電極５に、第１の帯域通過型フィルタ１が接続されている。また、電極９に、第２の帯域通過型フィルタ２も接続されている。 In the composite filter device 4 , an electrode 9 serving as an antenna terminal is provided on the first main surface 3 a of the piezoelectric substrate 3 . An input electrode 5 is connected to this electrode 9 . A first band-pass filter 1 is connected to the input electrode 5 . A second band-pass filter 2 is also connected to the electrode 9 .
　複合フィルタ装置４は、第１の帯域通過型フィルタ１及び第２の帯域通過型フィルタ２を有するデュプレクサである。 A composite filter device 4 is a duplexer having a first band-pass filter 1 and a second band-pass filter 2 .
　第１の帯域通過型フィルタ１では、入力電極５に、第２，第４のＩＤＴ電極１１ｂ，１１ｄの第１の端部が接続されている。第２，第４のＩＤＴ電極１１ｂ，１１ｄの第２の端部は、第２のグラウンド電極８に接続されている。第１，第２のグラウンド電極７，８が、第１の主面３ａ上に設けられている。同様に、第１の主面３ａ上に、受信端子としての信号電極６が設けられている。第２の帯域通過型フィルタ２は、第１の主面３ａ上に設けられた送信電極１０ａと、グラウンド電極１０ｂとに接続されている。 In the first band-pass filter 1, the input electrode 5 is connected to the first ends of the second and fourth IDT electrodes 11b and 11d. Second ends of the second and fourth IDT electrodes 11 b and 11 d are connected to the second ground electrode 8 . First and second ground electrodes 7 and 8 are provided on the first main surface 3a. Similarly, a signal electrode 6 as a receiving terminal is provided on the first main surface 3a. The second band-pass filter 2 is connected to a transmission electrode 10a provided on the first main surface 3a and a ground electrode 10b.
　第１，第３及び第５のＩＤＴ電極１１ａ，１１ｃ，１１ｅの第１の端部は、第１のグラウンド電極７または第２のグラウンド電極８に接続されている。第１，第３及び第５のＩＤＴ電極１１ａ，１１ｃ，１１ｅの第２の端部は、それぞれ、第２の縦結合共振子型弾性波フィルタ１２の第１のＩＤＴ電極１２ａ、第３のＩＤＴ電極１２ｃ及び第５のＩＤＴ電極１２ｅの第１の端部に接続されている。 The first ends of the first, third and fifth IDT electrodes 11a, 11c and 11e are connected to the first ground electrode 7 or the second ground electrode 8. The second ends of the first, third and fifth IDT electrodes 11a, 11c and 11e are the first IDT electrode 12a and the third IDT electrode 12a of the second longitudinally coupled resonator type elastic wave filter 12, respectively. It is connected to the first ends of the electrode 12c and the fifth IDT electrode 12e.
　第２の縦結合共振子型弾性波フィルタ１２では、第１のＩＤＴ電極１２ａの第２の端部が第１のグラウンド電極７に接続されている。第５のＩＤＴ電極１２ｅでは、第２の端部が第２のグラウンド電極８に接続されている。 In the second longitudinally coupled resonator type elastic wave filter 12 , the second end of the first IDT electrode 12 a is connected to the first ground electrode 7 . A second end of the fifth IDT electrode 12 e is connected to the second ground electrode 8 .
　第３のＩＤＴ電極１２ｃは、第１の櫛歯電極１２ｃ１と、第２，第３の櫛歯電極１２ｃ２，１２ｃ３とを有する。第１の櫛歯電極１２ｃ１が入力側の櫛歯電極であり、第２，第３の櫛歯電極１２ｃ２，１２ｃ３がグラウンド側の櫛歯電極である。言い換えれば、第２，第３の櫛歯電極１２ｃ２，１２ｃ３は、グラウンド側の櫛歯電極を２分割した構成に相当する。例えば、第２の櫛歯電極１２ｃ２の電極指の対数と、第３の櫛歯電極１２ｃ３の電極指の対数とが等しいことが好ましい。なお、第３のＩＤＴ電極１２ｃのグラウンド側の櫛歯電極は、３分割以上した構成であってもよい。すなわち、第３のＩＤＴ電極１２ｃは、第２，第３の櫛歯電極１２ｃ２，１２ｃ３に加えて、グラウンド電位に接続される少なくとも１つの他の櫛歯電極をさらに有していてもよい。 The third IDT electrode 12c has a first comb-shaped electrode 12c1 and second and third comb-shaped electrodes 12c2 and 12c3. The first comb-shaped electrode 12c1 is an input-side comb-shaped electrode, and the second and third comb-shaped electrodes 12c2 and 12c3 are ground-side comb-shaped electrodes. In other words, the second and third comb-teeth electrodes 12c2 and 12c3 correspond to a configuration in which the ground-side comb-teeth electrode is divided into two. For example, it is preferable that the number of pairs of electrode fingers of the second comb-teeth electrode 12c2 and the number of pairs of electrode fingers of the third comb-teeth electrode 12c3 are equal. The ground-side comb-teeth electrode of the third IDT electrode 12c may be divided into three or more. That is, the third IDT electrode 12c may further have at least one other comb-teeth electrode connected to the ground potential in addition to the second and third comb-teeth electrodes 12c2 and 12c3.
　第１の櫛歯電極１２ｃ１は、第１の帯域通過型フィルタ１の第３のＩＤＴ電極１１ｃに接続されている。他方、第２の櫛歯電極１２ｃ２は、第１のグラウンド電極７に接続されている。第３の櫛歯電極１２ｃ３は、第２のグラウンド電極８に接続されている。 The first comb-teeth electrode 12 c 1 is connected to the third IDT electrode 11 c of the first band-pass filter 1 . On the other hand, the second comb-teeth electrode 12c2 is connected to the first ground electrode 7. As shown in FIG. The third comb-teeth electrode 12c3 is connected to the second ground electrode 8. As shown in FIG.
　ここで、第１のグラウンド電極７及び第２のグラウンド電極８は、最終的にグラウンド電位に接続される。もっとも、圧電基板３においては、第１のグラウンド電極７と、第２のグラウンド電極８とは、電気的に接続されていない。 Here, the first ground electrode 7 and the second ground electrode 8 are finally connected to the ground potential. However, in the piezoelectric substrate 3, the first ground electrode 7 and the second ground electrode 8 are not electrically connected.
　本実施形態では、第１の主面３ａ上に、第１のグラウンド電極７及び第２のグラウンド電極８が設けられている。もっとも、本発明においては、図１１に示すように、第１のグラウンド電極７及び第２のグラウンド電極８は、圧電基板３の第２の主面３ｂ側に設けられていてもよい。その場合、第１のグラウンド電極７と第２の櫛歯電極１２ｃ２との電気的接続及び第２のグラウンド電極８と第３の櫛歯電極１２ｃ３との電気的接続は、スルーホール電極６１，６２などを用いて行えばよい。 In this embodiment, a first ground electrode 7 and a second ground electrode 8 are provided on the first main surface 3a. However, in the present invention, the first ground electrode 7 and the second ground electrode 8 may be provided on the second main surface 3b side of the piezoelectric substrate 3, as shown in FIG. In that case, the electrical connection between the first ground electrode 7 and the second comb-teeth electrode 12c2 and the electrical connection between the second ground electrode 8 and the third comb-teeth electrode 12c3 are made through the through- hole electrodes 61 and 62. and so on.
　第２，第４のＩＤＴ電極１２ｂ，１２ｄの第１の端部は、共通接続され、第１のグラウンド電極７に電気的に接続されている。第２，第４のＩＤＴ電極１２ｂ，１２ｄの第２の端部は、共通接続され、信号電極６に接続されている。 The first ends of the second and fourth IDT electrodes 12b and 12d are commonly connected and electrically connected to the first ground electrode 7. Second ends of the second and fourth IDT electrodes 12 b and 12 d are connected in common and connected to the signal electrode 6 .
　第１の帯域通過型フィルタ１の特徴は、上記のように、第２の縦結合共振子型弾性波フィルタ１２において、中央に位置している第３のＩＤＴ電極１２ｃが、第１～第３の櫛歯電極１２ｃ１，１２ｃ２，１２ｃ３を有し、第２の櫛歯電極１２ｃ２が第１のグラウンド電極７に接続されており、第３の櫛歯電極１２ｃ３が第２のグラウンド電極８に接続されていることにある。それによって、以下に述べるように、帯域外減衰量などのフィルタ特性の改善と、挿入損失の低減との両立を図ることができる。 A feature of the first bandpass filter 1 is that, as described above, in the second longitudinally coupled resonator type elastic wave filter 12, the third IDT electrode 12c located in the center , the second comb-teeth electrode 12c2 is connected to the first ground electrode 7, and the third comb-teeth electrode 12c3 is connected to the second ground electrode 8. There is As a result, as described below, it is possible to achieve both improvement in filter characteristics such as out-of-band attenuation and reduction in insertion loss.
　上記第１の帯域通過型フィルタ１の実施例と、比較例の弾性波フィルタ装置の減衰量－周波数特性を図３に示す。また、図４は、図３の要部を拡大して示す減衰量－周波数特性を示す図である。図３及び図４において、実線が実施例の結果を、破線が比較例の結果を示す。 FIG. 3 shows attenuation-frequency characteristics of an example of the first band-pass filter 1 and an acoustic wave filter device of a comparative example. Also, FIG. 4 is a diagram showing attenuation-frequency characteristics showing an enlarged main part of FIG. 3 and 4, the solid line indicates the results of the example, and the dashed line indicates the results of the comparative example.
　なお、実施例及び比較例の帯域通過型フィルタは、移動体通信のＢａｎｄ１２の受信フィルタである。Ｂａｎｄ１２の受信フィルタの通過帯域は、７２９ＭＨｚ～７４６ＭＨｚである。図３において、このＢａｎｄ１２の受信フィルタの通過帯域の下限である７２９ＭＨｚの位置を、Ｍ３で示す。同様に、上限である７４６ＭＨｚの位置を、Ｍ４で示す。他方、Ｂａｎｄ１２の送信フィルタの通過帯域は、６９９ＭＨｚ～７１６ＭＨｚである。図３において、下限である６９９ＭＨｚの位置を、Ｍ１で示し、上限である７１６ＭＨｚの位置を、Ｍ２で示す。 It should be noted that the band-pass filters of the examples and comparative examples are reception filters of Band 12 for mobile communication. The pass band of the reception filter of Band 12 is 729 MHz to 746 MHz. In FIG. 3, the position of 729 MHz, which is the lower limit of the passband of the reception filter of Band 12, is indicated by M3. Similarly, the position of the upper limit of 746 MHz is indicated by M4. On the other hand, the passband of the transmission filter of Band 12 is from 699 MHz to 716 MHz. In FIG. 3, the position of the lower limit of 699 MHz is indicated by M1, and the position of the upper limit of 716 MHz is indicated by M2.
　第１の帯域通過型フィルタ１は、Ｂａｎｄ１２の受信フィルタである。従って、帯域外減衰量を改善するには、送信フィルタの通過帯域である６９９ＭＨｚ～７１６ＭＨｚにおける減衰量が大きいことが求められる。ここで、減衰量については、Ｂａｎｄ１２の送信フィルタの通過帯域における最も減衰量が小さい部分がより大きいことが求められる。図４に矢印Ａで示すように、比較例の弾性波フィルタ装置に比べて、実施例の弾性波フィルタ装置によれば、７１５ＭＨｚ付近における最も減衰量が小さい部分における減衰量が大きくされていることがわかる。すなわち、実施例の弾性波フィルタ装置では、比較例の弾性波フィルタ装置に比べて、帯域外減衰量を改善することが可能とされている。 The first band-pass filter 1 is a Band 12 reception filter. Therefore, in order to improve the out-of-band attenuation, it is required that the attenuation in the passband of the transmission filter, 699 MHz to 716 MHz, is large. Here, as for the attenuation amount, it is required that the portion with the smallest attenuation amount in the passband of the transmission filter of Band 12 is larger. As shown by the arrow A in FIG. 4, according to the elastic wave filter device of the embodiment, the attenuation at the portion where the attenuation is the smallest near 715 MHz is increased compared to the elastic wave filter device of the comparative example. I understand. That is, in the elastic wave filter device of the embodiment, it is possible to improve the out-of-band attenuation amount compared to the elastic wave filter device of the comparative example.
　また、図５は、実施例及び比較例における送信フィルタ側から受信フィルタ側へのアイソレーション特性を示す図であり、図６は、図５の要部を拡大して示すアイソレーション特性の図である。 5 is a diagram showing the isolation characteristics from the transmission filter side to the reception filter side in the embodiment and the comparative example, and FIG. 6 is a diagram showing the isolation characteristics by enlarging the main part of FIG. be.
　アイソレーション特性においても、図６に矢印Ｂで示すように、７１５ＭＨｚ付近において、比較例に比べて実施例によれば、アイソレーションを改善することが可能とされている。 As for the isolation characteristics, as shown by the arrow B in FIG. 6, it is possible to improve the isolation in the embodiment compared to the comparative example in the vicinity of 715 MHz.
　上記のように、実施例において、帯域外減衰量の改善を図り得るのは、以下の理由によると考えられる。すなわち、第３のＩＤＴ電極１２ｃにおいて、グラウンド電位に接続される側の櫛歯電極が分割されており、それぞれ、圧電基板３に設けられており、互いに電気的に接続されていない第１，第２のグラウンド電極７，８に接続されている。そのため、比較例に比べて、第１のグラウンド電極７によるグラウンドと、第２のグラウンド電極８によるグラウンドとの差により、上記帯域外減衰量の拡大が図られていると考えられる。すなわち、第２の櫛歯電極１２ｃ２からグラウンド電位に至る回路と、第３の櫛歯電極１２ｃ３からグラウンド電位に至る回路との間において、インダクタンスＬ及び容量Ｃが異なってくる。そのため、第２，第３の櫛歯電極１２ｃ２，１２ｃ３に接続されるグラウンドに強弱が生じる。それによって、減衰極の周波数位置が変化し、上記のように、帯域外減衰量の拡大が図られていると考えられる。 It is believed that the reason why the out-of-band attenuation amount can be improved in the embodiment as described above is as follows. That is, in the third IDT electrode 12c, the comb-teeth electrode on the side connected to the ground potential is divided into first and second comb-shaped electrodes provided on the piezoelectric substrate 3 and not electrically connected to each other. 2 ground electrodes 7 and 8. Therefore, it is considered that the out-of-band attenuation is increased due to the difference between the ground by the first ground electrode 7 and the ground by the second ground electrode 8 compared to the comparative example. That is, the inductance L and the capacitance C differ between the circuit extending from the second comb-teeth electrode 12c2 to the ground potential and the circuit extending from the third comb-teeth electrode 12c3 to the ground potential. Therefore, the strength of the ground connected to the second and third comb-teeth electrodes 12c2 and 12c3 is generated. As a result, the frequency position of the attenuation pole is changed, and it is considered that the out-of-band attenuation amount is expanded as described above.
　よって、本実施形態の第１の帯域通過型フィルタ１では、挿入損失を悪化させることなく、帯域外減衰量、すなわち受信フィルタの送信帯域における減衰量の改善を図ることができ、かつ複合フィルタ装置４におけるアイソレーション特性を改善することができる。なお、本実施形態では、第１，第２の縦結合共振子型弾性波フィルタ１１，１２のうち第２の縦結合共振子型弾性波フィルタ１２において、第３のＩＤＴ電極１２ｃが第１～第３の櫛歯電極１２ｃ１～１２ｃ３を有する。もっとも、第１，第２の縦結合共振子型弾性波フィルタ１１，１２のうち少なくとも一方において、複数のＩＤＴ電極のうち中央に位置するＩＤＴ電極が、第１～第３の櫛歯電極を有していればよい。例えば、第１，第２の縦結合共振子型弾性波フィルタ１１，１２の双方において、複数のＩＤＴ電極のうち中央に位置するＩＤＴ電極が、第１～第３の櫛歯電極を有していてもよい。そして、第１の櫛歯電極が信号電位に接続されており、第２の櫛歯電極が第１のグラウンド電極７に接続されており、第３の櫛歯電極が第２のグラウンド電極８に接続されていればよい。 Therefore, in the first band-pass filter 1 of the present embodiment, it is possible to improve the out-of-band attenuation amount, that is, the attenuation amount in the transmission band of the reception filter, without deteriorating the insertion loss. 4 can be improved. In the present embodiment, in the second longitudinally coupled resonator-type elastic wave filter 12 of the first and second longitudinally coupled resonator-type elastic wave filters 11 and 12, the third IDT electrode 12c is connected to the first to It has third comb-teeth electrodes 12c1 to 12c3. However, in at least one of the first and second longitudinally coupled resonator type elastic wave filters 11 and 12, the central IDT electrode among the plurality of IDT electrodes has the first to third comb-teeth electrodes. It's fine if you do. For example, in both the first and second longitudinally coupled resonator-type elastic wave filters 11 and 12, the central IDT electrode among the plurality of IDT electrodes has the first to third comb-teeth electrodes. may The first comb-shaped electrode is connected to the signal potential, the second comb-shaped electrode is connected to the first ground electrode 7, and the third comb-shaped electrode is connected to the second ground electrode 8. It should be connected.
　図７は、本発明の第２の実施形態としての複合フィルタ装置２１の略図的回路図である。複合フィルタ装置２１はマルチプレクサである。複合フィルタ装置２１では、第１及び第２の帯域通過型フィルタ１及び２に加えて、さらに少なくとも１つの他の帯域通過型フィルタ２２が接続されている。このように、一端が共通接続された少なくとも１つの帯域通過型フィルタ２２をさらに有していてもよい。 FIG. 7 is a schematic circuit diagram of a composite filter device 21 as a second embodiment of the invention. Composite filter device 21 is a multiplexer. In the composite filter device 21, in addition to the first and second bandpass filters 1 and 2, at least one further bandpass filter 22 is also connected. Thus, it may further include at least one band-pass filter 22 having one end connected in common.
　図８は、本発明の第３の実施形態に係る弾性波フィルタ装置３１の略図的正面断面図である。弾性波フィルタ装置３１では、圧電基板が、圧電体層３６と、支持基板３２と、圧電体層３６と支持基板３２との間に積層された中間層３３とを有する。このように、本発明において、圧電基板は、圧電体層３６に他の層が積層された複合基板であってもよい。 FIG. 8 is a schematic front cross-sectional view of an elastic wave filter device 31 according to a third embodiment of the invention. In acoustic wave filter device 31 , the piezoelectric substrate has piezoelectric layer 36 , support substrate 32 , and intermediate layer 33 laminated between piezoelectric layer 36 and support substrate 32 . Thus, in the present invention, the piezoelectric substrate may be a composite substrate in which other layers are laminated on the piezoelectric layer 36 .
　弾性波フィルタ装置３１では、圧電体層３６上に、ＩＤＴ電極３７が設けられている。中間層３３は、高音速膜３４と、低音速膜３５とを有する。 In the acoustic wave filter device 31, an IDT electrode 37 is provided on the piezoelectric layer 36. The intermediate layer 33 has a high acoustic velocity film 34 and a low acoustic velocity film 35 .
　高音速膜３４は高音速材料からなる。高音速材料とは、伝搬するバルク波の音速が、圧電体層３６を伝搬する弾性波の音速よりも高い材料である。このような高音速材料としては、酸化アルミニウム、炭化ケイ素、窒化ケイ素、酸窒化ケイ素、シリコン、サファイア、タンタル酸リチウム、ニオブ酸リチウム、水晶、アルミナ、ジルコニア、コ－ジライト、ムライト、ステアタイト、フォルステライト、マグネシア、ＤＬＣ（ダイヤモンドライクカーボン）膜またはダイヤモンド、上記材料を主成分とする媒質、上記材料の混合物を主成分とする媒質等の様々な材料を用いることができる。 The high acoustic velocity film 34 is made of a high acoustic velocity material. A high acoustic velocity material is a material in which the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave propagating through the piezoelectric layer 36 . Such high sonic materials include aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, fort. Various materials such as stellite, magnesia, a DLC (diamond-like carbon) film or diamond, a medium containing the above materials as a main component, and a medium containing a mixture of the above materials as a main component can be used.
　低音速膜３５は低音速材料からなる。低音速材料とは、伝搬するバルク波の音速が、圧電体層３６を伝搬するバルク波の音速よりも低い材料をいう。このような低音速材料としては、酸化ケイ素、ガラス、酸窒化ケイ素、酸化タンタル、また、酸化ケイ素にフッ素や炭素やホウ素、水素、あるいはシラノール基を加えた化合物、上記材料を主成分とする媒質等の様々な材料を用いることができる。 The low sound velocity film 35 is made of a low sound velocity material. A low sound velocity material is a material in which a propagating bulk wave has a lower acoustic velocity than a bulk wave propagating through the piezoelectric layer 36 . Such low sound velocity materials include silicon oxide, glass, silicon oxynitride, tantalum oxide, compounds obtained by adding fluorine, carbon, boron, hydrogen, or silanol groups to silicon oxide, and media containing the above materials as main components. etc. can be used.
　支持基板３２は、シリコンなどの半導体材料またはアルミナなどの絶縁体材料からなる。 The support substrate 32 is made of a semiconductor material such as silicon or an insulating material such as alumina.
　なお、低音速膜３５を省略してもよく、あるいは、高音速膜３４と支持基板３２とを同じ高音速材料で一体化してもよい。すなわち、支持基板３２及び高音速膜３４が積層された構造に代えて、高音速材料からなる支持基板を用いてもよい。 The low acoustic velocity film 35 may be omitted, or the high acoustic velocity membrane 34 and the support substrate 32 may be integrated with the same high acoustic velocity material. That is, instead of the structure in which the supporting substrate 32 and the high acoustic velocity film 34 are laminated, a supporting substrate made of a high acoustic velocity material may be used.
　図９は、第４の実施形態に係る弾性波フィルタ装置の略図的正面断面図である。弾性波フィルタ装置４１では、圧電体層４６上にＩＤＴ電極４７が設けられている。支持基板４２と圧電体層４６との間に中間層４３が設けられている。中間層４３は、相対的に音響インピーダンスが高い高音響インピーダンス層４３ａ，４３ｃ，４３ｅと、相対的に音響インピーダンスが低い低音響インピーダンス層４３ｂ，４３ｄ，４３ｆとを交互に積層した構造を有する。このような音響反射層からなる中間層４３を用いてもよい。 FIG. 9 is a schematic front cross-sectional view of an elastic wave filter device according to a fourth embodiment. In the acoustic wave filter device 41 , an IDT electrode 47 is provided on the piezoelectric layer 46 . An intermediate layer 43 is provided between the support substrate 42 and the piezoelectric layer 46 . The intermediate layer 43 has a structure in which high acoustic impedance layers 43a, 43c, 43e with relatively high acoustic impedance and low acoustic impedance layers 43b, 43d, 43f with relatively low acoustic impedance are alternately laminated. An intermediate layer 43 made of such an acoustic reflection layer may be used.
　図１０は、本発明の第５実施形態に係る弾性波フィルタ装置の正面断面図である。弾性波フィルタ装置５１では、支持基板５２に、凹部５２ａが設けられている。この凹部５２ａにより、キャビティ５２ｂが構成されている。キャビティ５２ｂを覆うように圧電体層４６は、接合層５３を介して、支持基板５２に積層されている。このようなキャビティ５２ｂを有する弾性波フィルタ装置５１にも、本発明を適用することができる。 FIG. 10 is a front cross-sectional view of an elastic wave filter device according to a fifth embodiment of the invention. In the acoustic wave filter device 51, the support substrate 52 is provided with a recess 52a. This concave portion 52a constitutes a cavity 52b. The piezoelectric layer 46 is laminated on the support substrate 52 via the bonding layer 53 so as to cover the cavity 52b. The present invention can also be applied to the elastic wave filter device 51 having such a cavity 52b.
１…第１の帯域通過型フィルタ
２…第２の帯域通過型フィルタ
３…圧電基板
３ａ…第１の主面
３ｂ…第２の主面
４…複合フィルタ装置
５…入力電極
６…信号電極
７…第１のグラウンド電極
８…第２のグラウンド電極
９…電極
１０ａ…送信電極
１０ｂ…グラウンド電極
１１…第１の縦結合共振子型弾性波フィルタ
１１ａ…第１のＩＤＴ電極
１１ｂ…第２のＩＤＴ電極
１１ｃ…第３のＩＤＴ電極
１１ｄ…第４のＩＤＴ電極
１１ｅ…第５のＩＤＴ電極
１１ｆ，１１ｇ…反射器
１２…第２の縦結合共振子型弾性波フィルタ
１２ａ…第１のＩＤＴ電極
１２ｂ…第２のＩＤＴ電極
１２ｃ…第３のＩＤＴ電極
１２ｃ１…第１の櫛歯電極
１２ｃ２…第２の櫛歯電極
１２ｃ３…第３の櫛歯電極
１２ｄ…第４のＩＤＴ電極
１２ｅ…第５のＩＤＴ電極
１２ｆ，１２ｇ…反射器
２１…複合フィルタ装置
２２…帯域通過型フィルタ
３１…弾性波フィルタ装置
３２…支持基板
３３…中間層
３４…高音速膜
３５…低音速膜
３６…圧電体層
３７…ＩＤＴ電極
４１…弾性波フィルタ装置
４２…支持基板
４３…中間層
４３ａ，４３ｃ，４３ｅ…高音響インピーダンス層
４３ｂ，４３ｄ，４３ｆ…低音響インピーダンス層
４６…圧電体層
４７…ＩＤＴ電極
５１…弾性波フィルタ装置
５２…支持基板
５２ａ…凹部
５２ｂ…キャビティ
５３…接合層
６１，６２…スルーホール電極 Reference Signs List 1 First band-pass filter 2 Second band-pass filter 3 Piezoelectric substrate 3a First main surface 3b Second main surface 4 Composite filter device 5 Input electrode 6 Signal electrode 7 First ground electrode 8 Second ground electrode 9 Electrode 10a Transmission electrode 10b Ground electrode 11 First longitudinally coupled resonator type elastic wave filter 11a First IDT electrode 11b Second IDT Electrode 11c Third IDT electrode 11d Fourth IDT electrode 11e Fifth IDT electrode 11f, 11g Reflector 12 Second longitudinally coupled resonator type elastic wave filter 12a First IDT electrode 12b Second IDT electrode 12c Third IDT electrode 12c1 First comb-teeth electrode 12c2 Second comb-teeth electrode 12c3 Third comb-teeth electrode 12d Fourth IDT electrode 12e Fifth IDT electrode 12f, 12g -- reflector 21 -- composite filter device 22 -- bandpass filter 31 -- elastic wave filter device 32 -- support substrate 33 -- intermediate layer 34 -- high acoustic velocity film 35 -- low acoustic velocity film 36 -- piezoelectric layer 37 -- IDT electrode 41 elastic wave filter device 42 support substrate 43 intermediate layers 43a, 43c, 43e high acoustic impedance layers 43b, 43d, 43f low acoustic impedance layer 46 piezoelectric layer 47 IDT electrode 51 elastic wave filter device 52 ... support substrate 52a ... concave portion 52b ... cavity 53 ... bonding layers 61, 62 ... through-hole electrode

Claims (13)

  1. 　圧電基板と、
    　前記圧電基板に構成された帯域通過型フィルタとを備え、
    　前記帯域通過型フィルタが、複数のＩＤＴ電極を有する第１，第２の縦結合共振子型弾性波フィルタを有し、前記第１の縦結合共振子型弾性波フィルタに、前記第２の縦結合共振子型弾性波フィルタが縦続接続されており、
    　前記圧電基板に設けられた第１のグラウンド電極と、前記圧電基板に設けられており、前記第１のグラウンド電極と前記圧電基板において電気的に接続されていない、第２のグラウンド電極とを有し、
    　前記第１の縦結合共振子型弾性波フィルタ及び前記第２の縦結合共振子型弾性波フィルタのうちの少なくとも一方において、前記複数のＩＤＴ電極のうち中央に位置しているＩＤＴ電極が、信号電位に接続される第１の櫛歯電極と、グラウンド電位に接続される第２及び第３の櫛歯電極とを有し、
    　前記第２の櫛歯電極が、前記第１のグラウンド電極に接続されており、前記第３の櫛歯電極が、前記第２のグラウンド電極に接続されている、弾性波フィルタ装置。     a piezoelectric substrate;
    A band-pass filter configured on the piezoelectric substrate,
    The band-pass filter has first and second longitudinally coupled resonator-type elastic wave filters having a plurality of IDT electrodes, and the first longitudinally-coupled resonator-type elastic wave filter includes the second longitudinally Coupling resonator type elastic wave filters are cascaded,
    A first ground electrode provided on the piezoelectric substrate, and a second ground electrode provided on the piezoelectric substrate and not electrically connected between the first ground electrode and the piezoelectric substrate. death,
    In at least one of the first longitudinally coupled resonator-type elastic wave filter and the second longitudinally coupled resonator-type elastic wave filter, the IDT electrode positioned at the center of the plurality of IDT electrodes receives a signal having a first comb-teeth electrode connected to a potential and second and third comb-teeth electrodes connected to a ground potential;
    The acoustic wave filter device, wherein the second comb-teeth electrode is connected to the first ground electrode, and the third comb-teeth electrode is connected to the second ground electrode.
  2. 　前記第１の縦結合共振子型弾性波フィルタ及び前記第２の縦結合共振子型弾性波フィルタの双方において、前記中央に位置しているＩＤＴ電極が、前記第１の櫛歯電極と、前記第２及び第３の櫛歯電極とを有する、請求項１に記載の弾性波フィルタ装置。 In both the first longitudinally-coupled resonator-type elastic wave filter and the second longitudinally-coupled resonator-type elastic wave filter, the IDT electrode located in the center is composed of the first comb-teeth electrode and the 2. The elastic wave filter device according to claim 1, comprising second and third comb-teeth electrodes.
  3. 　前記第２の櫛歯電極の電極指の対数と、前記第３の櫛歯電極の電極指の対数とが等しい、請求項１または２に記載の弾性波フィルタ装置。 3. The elastic wave filter device according to claim 1, wherein the number of pairs of electrode fingers of said second comb-shaped electrode is equal to the number of pairs of electrode fingers of said third comb-shaped electrode.
  4. 　前記中央に位置しているＩＤＴ電極が、前記第２の櫛歯電極及び前記第３の櫛歯電極に加えて、グラウンド電位に接続される少なくとも１つの他の櫛歯電極をさらに有する、請求項１～３のいずれか１項に記載の弾性波フィルタ装置。 3. The centrally located IDT electrode further comprises at least one other comb electrode connected to a ground potential in addition to the second comb electrode and the third comb electrode. 4. The elastic wave filter device according to any one of 1 to 3.
  5. 　前記第１の縦結合共振子型弾性波フィルタまたは前記第２の縦結合共振子型弾性波フィルタに縦続接続されている少なくとも１つの縦結合共振子型弾性波フィルタをさらに有する、請求項１～４のいずれか１項に記載の弾性波フィルタ装置。 1. Further comprising at least one longitudinally coupled resonator-type elastic wave filter cascade-connected to said first longitudinally-coupled resonator-type elastic wave filter or said second longitudinally-coupled resonator-type elastic wave filter. 5. The elastic wave filter device according to any one of 4.
  6. 　前記第１のグラウンド電極及び前記第２のグラウンド電極が、前記圧電基板の第１の主面に設けられている、請求項１～５のいずれか１項に記載の弾性波フィルタ装置。 The acoustic wave filter device according to any one of claims 1 to 5, wherein the first ground electrode and the second ground electrode are provided on the first main surface of the piezoelectric substrate.
  7. 　前記第１のグラウンド電極及び前記第２のグラウンド電極が、前記圧電基板の第２の主面に設けられている、請求項１～５のいずれか１項に記載の弾性波フィルタ装置。 The elastic wave filter device according to any one of claims 1 to 5, wherein the first ground electrode and the second ground electrode are provided on the second main surface of the piezoelectric substrate.
  8. 　前記圧電基板が、圧電単結晶からなる、請求項１～７のいずれか１項に記載の弾性波フィルタ装置。 The acoustic wave filter device according to any one of claims 1 to 7, wherein the piezoelectric substrate is made of piezoelectric single crystal.
  9. 　前記圧電基板が、圧電体層と、前記圧電体層に直接または間接に積層された支持基板とを有する複合基板である、請求項１～７のいずれか１項に記載の弾性波フィルタ装置。 The elastic wave filter device according to any one of claims 1 to 7, wherein the piezoelectric substrate is a composite substrate having a piezoelectric layer and a support substrate laminated directly or indirectly on the piezoelectric layer.
  10. 　前記圧電体層と前記支持基板との間に積層された中間層をさらに備える、請求項９に記載の弾性波フィルタ装置。 The acoustic wave filter device according to claim 9, further comprising an intermediate layer laminated between said piezoelectric layer and said support substrate.
  11. 　請求項１～１０のいずれか１項に記載の弾性波フィルタ装置と、
    　前記弾性波フィルタ装置に一端が共通接続された少なくとも１つの他の帯域通過型フィルタとを備える、複合フィルタ装置。     The elastic wave filter device according to any one of claims 1 to 10;
    and at least one other band-pass filter having one end commonly connected to the acoustic wave filter device.
  12. 　前記少なくとも１つの他の帯域通過型フィルタが１つの帯域通過型フィルタであり、デュプレクサが構成されている、請求項１１に記載の複合フィルタ装置。 The composite filter device according to claim 11, wherein said at least one other bandpass filter is one bandpass filter and constitutes a duplexer.
  13. 　前記少なくとも１つの他の帯域通過型フィルタが複数設けられており、マルチプレクサが構成されている、請求項１１に記載の複合フィルタ装置。 12. The composite filter device according to claim 11, wherein a plurality of said at least one other band-pass filter are provided to constitute a multiplexer.
PCT/JP2022/028890 2021-08-19 2022-07-27 Elastic wave filter device and complex filter device WO2023021949A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007124085A (en) * 2005-10-26 2007-05-17 Fujitsu Media Device Kk Surface acoustic wave device
JP2007123992A (en) * 2005-10-25 2007-05-17 Kyocera Corp Surface acoustic wave element and communication apparatus
WO2007129548A1 (en) * 2006-05-08 2007-11-15 Murata Manufacturing Co., Ltd. Elastic wave filter device and duplexer
JP2015002375A (en) * 2013-06-13 2015-01-05 株式会社村田製作所 Demultiplexing device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007123992A (en) * 2005-10-25 2007-05-17 Kyocera Corp Surface acoustic wave element and communication apparatus
JP2007124085A (en) * 2005-10-26 2007-05-17 Fujitsu Media Device Kk Surface acoustic wave device
WO2007129548A1 (en) * 2006-05-08 2007-11-15 Murata Manufacturing Co., Ltd. Elastic wave filter device and duplexer
JP2015002375A (en) * 2013-06-13 2015-01-05 株式会社村田製作所 Demultiplexing device

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