WO2011065048A1 - Acoustic wave filter and branching filter - Google Patents

Acoustic wave filter and branching filter Download PDF

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Publication number
WO2011065048A1
WO2011065048A1 PCT/JP2010/060723 JP2010060723W WO2011065048A1 WO 2011065048 A1 WO2011065048 A1 WO 2011065048A1 JP 2010060723 W JP2010060723 W JP 2010060723W WO 2011065048 A1 WO2011065048 A1 WO 2011065048A1
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Prior art keywords
electrode
comb
signal terminal
idt
wave filter
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PCT/JP2010/060723
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French (fr)
Japanese (ja)
Inventor
保昭 新
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株式会社村田製作所
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Publication of WO2011065048A1 publication Critical patent/WO2011065048A1/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
    • H03H9/05—Holders; Supports
    • H03H9/058—Holders; Supports for surface acoustic wave devices
    • H03H9/059—Holders; Supports for surface acoustic wave devices consisting of mounting pads or bumps
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/0023—Balance-unbalance or balance-balance networks
    • H03H9/0028—Balance-unbalance or balance-balance networks using surface acoustic wave devices
    • H03H9/0033—Balance-unbalance or balance-balance networks using surface acoustic wave devices having one acoustic track only
    • H03H9/0038—Balance-unbalance or balance-balance networks using surface acoustic wave devices having one acoustic track only the balanced terminals being on the same side of the track
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/0023—Balance-unbalance or balance-balance networks
    • H03H9/0028—Balance-unbalance or balance-balance networks using surface acoustic wave devices
    • H03H9/0047—Balance-unbalance or balance-balance networks using surface acoustic wave devices having two acoustic tracks
    • H03H9/0066—Balance-unbalance or balance-balance networks using surface acoustic wave devices having two acoustic tracks being electrically parallel
    • H03H9/0071—Balance-unbalance or balance-balance networks using surface acoustic wave devices having two acoustic tracks being electrically parallel the balanced terminals being on the same side of the tracks
    • 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
    • H03H9/6423—Means for obtaining a particular transfer characteristic
    • H03H9/6433—Coupled resonator filters
    • H03H9/644—Coupled resonator filters having two acoustic tracks
    • H03H9/6456—Coupled resonator filters having two acoustic tracks being electrically coupled
    • H03H9/6469—Coupled resonator filters having two acoustic tracks being electrically coupled via two connecting electrodes
    • 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
    • H03H9/6423—Means for obtaining a particular transfer characteristic
    • H03H9/6433—Coupled resonator filters
    • H03H9/6483—Ladder SAW filters
    • 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
    • H03H9/725—Duplexers
    • 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
    • H03H9/14517—Means for weighting
    • H03H9/14529—Distributed tap
    • H03H9/14535—Position weighting

Definitions

  • the present invention relates to an elastic wave filter and a duplexer. More specifically, the present invention relates to a longitudinally coupled resonator-type elastic wave filter and a duplexer having first and second balanced signal terminals and having a balanced-unbalanced conversion function.
  • FIG. 17 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1 below.
  • the longitudinally coupled resonator type surface acoustic wave filter 100 includes first to third IDT electrodes 101 to 103 formed along the propagation direction of the surface acoustic wave.
  • Each of the first to third IDT electrodes 101 to 103 is composed of a pair of comb-like electrodes.
  • the comb-like electrode on one side of the second IDT electrode 102 is connected to the unbalanced signal terminal 106, and the comb-like electrode on the other side is connected to the ground potential.
  • the comb-like electrodes on one side of the first and third IDT electrodes 101 and 103 are connected to the ground potential, and the comb-like electrodes on the other side are the first or second balanced signal terminals 107 and 108. It is connected to the.
  • Reflectors 104 and 105 are formed on both sides of the region where the first to third IDT electrodes 101 to 103 are formed in the propagation direction of the surface acoustic wave.
  • the longitudinally coupled resonator type surface acoustic wave filter 100 is configured such that the signal output from the first balanced signal terminal 107 and the signal output from the second balanced signal terminal 108 are in opposite phase to each other. Has been. That is, the first IDT electrode 101 has a configuration obtained by inverting the third IDT electrode 103. Therefore, the longitudinally coupled resonator type surface acoustic wave filter 100 has a balance-unbalance conversion function.
  • Patent Document 1 discloses a longitudinally coupled resonator type surface acoustic wave filter different from the longitudinally coupled resonator type surface acoustic wave filter 100 shown in FIG.
  • a schematic plan view of the longitudinally coupled resonator type surface acoustic wave filter is shown in FIG.
  • the longitudinally coupled resonator type surface acoustic wave filter 200 includes four longitudinally coupled resonator type surface acoustic wave filter units 201 to 204.
  • Each of the longitudinally coupled resonator-type surface acoustic wave filter sections 201 to 204 includes three IDT electrodes formed along the propagation direction of the surface acoustic wave.
  • a pair of reflectors is formed on both sides in the propagation direction of the surface acoustic wave in the region where the three IDT electrodes are formed.
  • the IDT electrodes of the longitudinally coupled resonator type surface acoustic wave filter portions 201 to 204 are each composed of a pair of comb-like electrodes.
  • the comb-like electrode on one side of the IDT electrode located in the center in the propagation direction of the surface acoustic waves of each of the longitudinally coupled resonator type surface acoustic wave filter units 201 and 202 is connected in common to the unbalanced signal terminal 205.
  • the comb electrode on the other side is connected to the ground potential.
  • the comb-like electrodes on one side of the IDT electrodes located on both sides in the propagation direction of the surface acoustic waves of the longitudinally coupled resonator type surface acoustic wave filter units 201 and 202 are connected to the ground potential, and the other side
  • the comb-like electrode is connected to the comb-like electrode on one side of the IDT electrode located on both sides of the longitudinally coupled resonator-type surface acoustic wave filter sections 203 and 204 in the propagation direction of the respective surface acoustic waves.
  • the comb-like electrodes on the other side of the IDT electrodes located on both sides in the propagation direction of the surface acoustic waves of the longitudinally coupled resonator type surface acoustic wave filter sections 203 and 204 are connected to the ground potential.
  • the comb-like electrode on one side of the IDT electrode located at the center in the propagation direction of the surface acoustic waves of each of the longitudinally coupled resonator type surface acoustic wave filter sections 203 and 204 is connected to the ground potential, and the other side
  • the comb-like electrode is connected to the first or second balanced signal terminal 206 or 207.
  • the longitudinally coupled resonator type surface acoustic wave filter 200 is configured such that the signal output from the first balanced signal terminal 206 and the signal output from the second balanced signal terminal 207 are in opposite phase to each other.
  • the IDT electrode located at the center in the propagation direction of the surface acoustic wave of the longitudinally coupled resonator type surface acoustic wave filter unit 203 is located at the center in the propagation direction of the surface acoustic wave of the longitudinally coupled resonator type surface acoustic wave filter unit 204
  • the IDT electrode positioned is inverted.
  • the longitudinally coupled resonator type surface acoustic wave filter 200 has a balanced-unbalanced conversion function, like the longitudinally coupled resonator type surface acoustic wave filter 100.
  • the ground is usually connected to the ground potential together with the electrodes constituting the IDT electrode and the reflector on the piezoelectric substrate.
  • An electrode pad is formed.
  • the comb-like electrode on the side connected to the ground potential of the IDT electrode is connected to the ground electrode pad.
  • the number of grounding electrode pads is made smaller than the number of IDT electrodes.
  • a plurality of IDT electrodes are commonly connected to one ground electrode pad.
  • the comb-like electrode on one side of the first IDT electrode 101 and the comb-like electrode on one side of the third IDT electrode 103 are connected to a common ground electrode pad.
  • the present inventor when a plurality of IDT electrodes are commonly connected to one ground electrode pad, It has been found that the balance of signals between balanced signal terminals may deteriorate.
  • the present invention has been made in view of such points, and an object of the present invention is to suppress deterioration of the balance of signals between balanced signal terminals in a longitudinally coupled resonator type elastic wave filter having a balanced-unbalanced conversion function. There is to do.
  • a longitudinally coupled resonator type elastic wave filter having a balanced-unbalanced conversion function That is, a comb-like electrode on one side of the IDT electrode connected to the first balanced signal terminal and a comb-like electrode on one side of the IDT electrode connected to the second balanced signal terminal are shared. It has been found that the signal balance between the first and second balanced signal terminals deteriorates when connected to the grounding electrode pad. Further, the inventor of the present invention is caused by a comb-like electrode on one side of the IDT electrode connected to the first balanced signal terminal and one side of the IDT electrode connected to the second balanced signal terminal. It has been found that by connecting the comb-like electrode to a common ground electrode pad, two currents in a reverse phase are combined on the piezoelectric substrate. As a result, the inventor has made the present invention.
  • the acoustic wave filter according to the present invention includes an unbalanced signal terminal, first and second balanced signal terminals, a piezoelectric substrate, and the unbalanced signal terminal and the first and second balanced signals on the piezoelectric substrate.
  • An elastic wave filter unit connected between the terminals and a first and a second grounding electrode pad formed on the piezoelectric substrate and connected to the ground potential.
  • the unbalanced signal includes a plurality of IDT electrodes formed on the piezoelectric substrate, and at least one of the plurality of IDT electrodes has at least one comb-like electrode connected to the unbalanced signal terminal.
  • At least one IDT electrode of the plurality of IDT electrodes includes at least one comb-like electrode connected to the first balanced signal terminal and a first ground electrode pad.
  • a first balanced signal terminal-side IDT electrode having at least one comb-like electrode connected to the at least one IDT electrode, wherein at least one IDT electrode of the plurality of IDT electrodes is connected to the second balanced signal terminal.
  • a first balanced signal terminal-side IDT electrode having at least one comb-like electrode and at least one comb-like electrode connected to the second ground electrode pad,
  • the terminal-side IDT electrode and the second balanced signal terminal-side IDT electrode are configured to be reversed with the direction orthogonal to the propagation direction of the acoustic wave as the axis of symmetry.
  • the elastic wave filter further includes a third grounding electrode pad formed on the piezoelectric substrate and connected to the ground potential, and the first of the plurality of IDT electrodes.
  • the IDT electrodes other than the balanced signal terminal side IDT electrode and the second balanced signal terminal side IDT electrode have at least one comb-like electrode connected to the third ground electrode pad.
  • the duplexer according to the present invention includes the elastic wave filter according to the present invention.
  • the comb-like electrode on one side of the first balanced signal terminal side IDT electrode and the comb-like electrode on one side of the second balanced signal terminal side IDT electrode are connected to different ground electrode pads. ing. For this reason, it can suppress that the electric current which flows through the 1st balanced signal terminal side IDT electrode and the electric current which flows through the 2nd balanced signal terminal side IDT electrode which are in a mutually reverse phase relationship match on a piezoelectric substrate. As a result, it is possible to suppress deterioration in the degree of balance of the signal between the first and second balanced signal terminals.
  • FIG. 1 is a schematic diagram of a duplexer according to an embodiment of the present invention.
  • FIG. 2 is a schematic plan view of a reception-side filter according to one embodiment of the present invention.
  • FIG. 3 is a schematic plan view of a receiving filter according to an embodiment of the present invention.
  • FIG. 4 is a schematic plan view of a reception-side filter in the comparative example.
  • FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal and the first reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal and the first reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a
  • FIG. 6 is a graph showing the attenuation characteristic between the antenna terminal and the second reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 7 is a graph showing the differential attenuation characteristic between the antenna terminal and the first and second receiving-side signal terminals in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 8 is a graph showing the isolation characteristics between the transmission-side signal terminal and the first reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 9 is a graph showing the isolation characteristics between the transmission-side signal terminal and the second reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 10 is a graph showing the differential isolation characteristics between the transmission-side signal terminal and the first and second reception-side signal terminals in the duplexer according to the embodiment of the present invention and the duplexer according to the comparative example. is there.
  • a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example.
  • FIG. 11 is a schematic configuration diagram of a reception-side filter according to the first modification.
  • FIG. 12 is a schematic configuration diagram of a reception-side filter according to the second modification.
  • FIG. 13 is a schematic configuration diagram of a reception-side filter according to a third modification.
  • FIG. 14 is a schematic configuration diagram of a reception-side filter according to a fourth modification.
  • FIG. 15 is a schematic cross-sectional view in which a part of the reception-side filter according to the fifth modification is enlarged.
  • FIG. 16 is a schematic cross-sectional view in which a part of the reception-side filter according to the sixth modification is enlarged.
  • FIG. 17 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1.
  • FIG. 18 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1, which is different from the longitudinally coupled resonator type surface acoustic wave filter shown in FIG.
  • duplexer 1 shown in FIG. 1 As an example.
  • the duplexer 1 shown in FIG. 1 is merely an example.
  • the present invention is not limited to the duplexer 1.
  • the duplexer 1 shown in FIG. 1 is a duplexer corresponding to UMTS (Universal Mobile Telecommunications System) -BAND5. Note that the pass band of the reception-side filter of UMTS-BAND5 is 869 MHz to 894 MHz. The pass band of the transmission side filter of UMTS-BAND5 is 824 MHz to 849 MHz.
  • UMTS Universal Mobile Telecommunications System
  • the duplexer 1 includes an antenna terminal 10, a transmission-side signal terminal 12, and first and second reception-side signal terminals 21 and 22.
  • the antenna terminal 10 is connected to an antenna (Ant.) Of a communication device on which the duplexer 1 is mounted.
  • a matching inductor 11 is connected between a connection point between the antenna (Ant.) And the antenna terminal 10 and the ground potential.
  • the matching inductor 11 is configured by a chip inductor.
  • the matching inductor 11 may be configured by an inductor other than the chip inductor.
  • a transmission-side filter 13 is connected between the antenna terminal 10 and the transmission-side signal terminal 12.
  • the transmission filter 13 is a ladder-type elastic wave filter using a surface acoustic wave or a boundary acoustic wave.
  • the transmission-side filter is not limited to a ladder-type elastic wave filter.
  • the transmission filter may be, for example, a longitudinally coupled resonator type elastic wave filter.
  • a reception-side filter 20 is connected between the antenna terminal 10 and the first and second reception-side signal terminals 21 and 22.
  • FIG. 2 is a schematic plan view of the reception-side filter 20.
  • FIG. 3 is a schematic plan view of the reception filter 20.
  • the reflector is schematically drawn as a rectangle with “x” inside.
  • both the reflector and the IDT electrode are schematically drawn as quadrilaterals with “x” inside.
  • the number of electrode fingers and the like is drawn less than the actual number.
  • the receiving side filter 20 shown in FIGS. 1 to 3 is an elastic wave filter using a surface acoustic wave or a boundary acoustic wave.
  • the reception-side filter 20 is a surface acoustic wave filter using surface acoustic waves.
  • the reception-side filter 20 includes an unbalanced signal terminal 23 and first and second balanced signal terminals 24 and 25. As shown in FIG. 1, the unbalanced signal terminal 23 is connected to the antenna terminal 10. The first balanced signal terminal 24 is connected to the first receiving signal terminal 21. The second balanced signal terminal 25 is connected to the second receiving signal terminal 22.
  • an elastic wave filter unit 28 formed on the piezoelectric substrate 26 is formed between the unbalanced signal terminal 23 and the first and second balanced signal terminals 24 and 25.
  • the elastic wave filter unit 28 is a longitudinally coupled resonator type elastic wave filter unit having a balanced-unbalanced conversion function.
  • the elastic wave filter unit 28 includes first to fourth longitudinally coupled resonator type elastic wave filter units 30, 40, 50 and 60.
  • the piezoelectric substrate 26 can be formed by a piezoelectric single crystal substrate such as a LiNbO 3 substrate or a LiTaO 3 substrate, for example.
  • the first and second longitudinally coupled resonator type acoustic wave filter units 30 and 40 are connected between the unbalanced signal terminal 23 and the first balanced signal terminal 24. ing.
  • the first longitudinally coupled resonator type acoustic wave filter unit 30 is cascade-connected to the second longitudinally coupled resonator type acoustic wave filter unit 40.
  • the first longitudinally coupled resonator type elastic wave filter unit 30 includes three IDT electrodes 31 to 33 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 34 and 35 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 31 to 33 are formed.
  • the IDT electrode 31 is located in the center of the IDT electrodes 31 to 33 in the propagation direction of the elastic wave.
  • the IDT electrode 31 includes first and second comb-like electrodes 31a and 31b.
  • the IDT electrode 32 is formed adjacent to the IDT electrode 31 in the propagation direction of the elastic wave.
  • the IDT electrode 32 includes first and second comb-like electrodes 32a and 32b.
  • the IDT electrode 33 is formed adjacent to the IDT electrode 31 in the propagation direction of the elastic wave.
  • the IDT electrode 33 includes first and second comb-like electrodes 33a and 33b.
  • the second longitudinally coupled resonator type acoustic wave filter unit 40 has three IDT electrodes 41 to 43 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 44 and 45 are formed on both sides in the elastic wave propagation direction in the region where the IDT electrodes 41 to 43 are formed.
  • the IDT electrode 41 is located in the center of the IDT electrodes 41 to 43 in the propagation direction of the elastic wave.
  • the IDT electrode 41 includes first and second comb-like electrodes 41a and 41b.
  • the IDT electrode 42 is formed adjacent to the IDT electrode 41 in the propagation direction of the elastic wave.
  • the IDT electrode 42 includes first and second comb-like electrodes 42a and 42b.
  • the IDT electrode 43 is formed adjacent to the IDT electrode 41 in the propagation direction of the elastic wave.
  • the IDT electrode 43 includes first and second comb-like electrodes 43a and 43b.
  • the first comb-shaped electrode 31 a of the IDT electrode 31 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 31b of the IDT electrode 31 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the first comb-like electrode 32a of the IDT electrode 32 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the second comb-shaped electrode 32 b of the IDT electrode 32 is connected to the first comb-shaped electrode 42 a of the IDT electrode 42 of the second longitudinally coupled resonator type acoustic wave filter unit 40.
  • the first comb-like electrode 33a of the IDT electrode 33 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the second comb-like electrode 33 b of the IDT electrode 33 is connected to the first comb-like electrode 43 a of the IDT electrode 43 of the second longitudinally coupled resonator type acoustic wave filter unit 40.
  • the first comb-like electrode 41a of the IDT electrode 41 is connected to a ground electrode pad 29a (see FIG. 3) connected to the ground potential.
  • the second comb-like electrode 41 b of the IDT electrode 41 is connected to the first balanced signal terminal 24.
  • the first comb-shaped electrode 42 a of the IDT electrode 42 is connected to the second comb-shaped electrode 32 b of the IDT electrode 32 of the first longitudinally coupled resonator type acoustic wave filter unit 30.
  • the second comb-like electrode 42b of the IDT electrode 42 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the first comb-shaped electrode 43 a of the IDT electrode 43 is connected to the second comb-shaped electrode 33 b of the IDT electrode 33 of the first longitudinally coupled resonator type acoustic wave filter unit 30.
  • the second comb-like electrode 43b of the IDT electrode 43 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • an acoustic wave resonator 70 is connected between the first longitudinally coupled resonator type acoustic wave filter unit 30 and the unbalanced signal terminal 23.
  • the acoustic wave resonator 70 includes an IDT electrode 70 a formed on the piezoelectric substrate 26.
  • the IDT electrode 70a includes first and second comb-like electrodes 70a1 and 70a2.
  • the first comb-like electrode 70 a 1 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 70 a 2 is connected to the first comb-like electrode 31 a of the IDT electrode 31 of the first longitudinally coupled resonator type acoustic wave filter unit 30.
  • the third and fourth longitudinally coupled resonator type acoustic wave filter units 50 and 60 are connected between the unbalanced signal terminal 23 and the second balanced signal terminal 25. ing.
  • the third longitudinally coupled resonator type acoustic wave filter unit 50 is cascade-connected to the fourth longitudinally coupled resonator type acoustic wave filter unit 60.
  • the third longitudinally coupled resonator type acoustic wave filter unit 50 includes three IDT electrodes 51 to 53 formed on the piezoelectric substrate 26 along the propagation direction of the acoustic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 54 and 55 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 51 to 53 are formed.
  • the IDT electrode 51 is located in the center of the IDT electrodes 51 to 53 in the propagation direction of the elastic wave.
  • the IDT electrode 51 includes first and second comb-like electrodes 51a and 51b.
  • the IDT electrode 52 is formed adjacent to the IDT electrode 51 in the elastic wave propagation direction.
  • the IDT electrode 52 includes first and second comb-like electrodes 52a and 52b.
  • the IDT electrode 53 is formed adjacent to the IDT electrode 51 in the elastic wave propagation direction.
  • the IDT electrode 53 includes first and second comb-like electrodes 53a and 53b.
  • the fourth longitudinally coupled resonator type elastic wave filter unit 60 includes three IDT electrodes 61 to 63 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 64 and 65 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 61 to 63 are formed.
  • the IDT electrode 61 is located at the center of the IDT electrodes 61 to 63 in the elastic wave propagation direction.
  • the IDT electrode 61 includes first and second comb-like electrodes 61a and 61b.
  • the IDT electrode 62 is formed adjacent to the IDT electrode 61 in the propagation direction of the elastic wave.
  • the IDT electrode 62 includes first and second comb-like electrodes 62a and 62b.
  • the IDT electrode 63 is formed adjacent to the IDT electrode 61 in the propagation direction of the elastic wave.
  • the IDT electrode 63 includes first and second comb-like electrodes 63a and 63b.
  • the first comb-like electrode 51 a of the IDT electrode 51 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 51b of the IDT electrode 51 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the first comb-like electrode 52a of the IDT electrode 52 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the second comb-like electrode 52 b of the IDT electrode 52 is connected to the first comb-like electrode 62 a of the IDT electrode 62 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60.
  • the first comb-like electrode 53a of the IDT electrode 53 is connected to the ground electrode pad 27 (see FIG.
  • the second comb-like electrode 53 b of the IDT electrode 53 is connected to the first comb-like electrode 63 a of the IDT electrode 63 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60.
  • the first comb-like electrode 61a of the IDT electrode 61 is connected to a ground electrode pad 29b (see FIG. 3) connected to the ground potential.
  • the second comb-like electrode 61 b of the IDT electrode 61 is connected to the second balanced signal terminal 25.
  • the first comb-like electrode 62 a of the IDT electrode 62 is connected to the second comb-like electrode 52 b of the IDT electrode 52 of the third longitudinally coupled resonator type acoustic wave filter unit 50.
  • the second comb-like electrode 62b of the IDT electrode 62 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • the first comb-like electrode 63 a of the IDT electrode 63 is connected to the second comb-like electrode 53 b of the IDT electrode 53 of the third longitudinally coupled resonator type acoustic wave filter unit 50.
  • the second comb-like electrode 63b of the IDT electrode 63 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential.
  • an acoustic wave resonator 71 is connected between the third longitudinally coupled resonator type acoustic wave filter unit 50 and the unbalanced signal terminal 23.
  • the acoustic wave resonator 71 includes an IDT electrode 71 a formed on the piezoelectric substrate 26.
  • the IDT electrode 71a includes first and second comb-like electrodes 71a1 and 71a2.
  • the first comb-like electrode 71 a 1 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 71a2 is connected to the first comb-like electrode 51a of the IDT electrode 51 of the third longitudinally coupled resonator type acoustic wave filter unit 50.
  • the IDT electrode 41 and the IDT electrode 61 are configured to be reversed with the direction orthogonal to the propagation direction of the elastic wave as the axis of symmetry. Therefore, in the acoustic wave filter unit 28, the signal output from the first balanced signal terminal 24 and the signal output from the second balanced signal terminal 25 are in an opposite phase relationship.
  • an insulating film 15 is formed between the intersecting wirings.
  • the insulating film 15 insulates the intersecting wires from each other.
  • the material of the insulating film 15 is not particularly limited.
  • the insulating film 15 can be formed of, for example, a resin such as polyimide or an inorganic dielectric such as SiO 2 or SiN.
  • the IDT electrode, the reflector, and the like in the present embodiment can be formed of an appropriate conductive material.
  • the IDT electrode, the reflector, and the like can be formed of a metal such as Al, Cu, Ni, Au, Ag, Pt, Au, or Cr, or an alloy containing at least one of these metals.
  • the IDT electrode, the reflector, and the like may be configured by, for example, a conductive film stack in which a plurality of conductive films are stacked.
  • the IDT electrode 41a of the IDT electrode 41 connected to the first balanced signal terminal 24 and the IDT connected to the second balanced signal terminal 25 are used.
  • the first comb-like electrode 61a of the electrode 61 is connected to different grounding electrode pads 29a and 29b on the piezoelectric substrate. For this reason, it is possible to effectively suppress the current flowing through the IDT electrode 41 and the current flowing through the IDT electrode 61, which are in an opposite phase relationship, from being combined on the piezoelectric substrate 26. As a result, it is possible to effectively suppress the deterioration of the balance between the first and second balanced signal terminals 24 and 25, as supported by the following examples. Moreover, since the deterioration of the balance degree between the 1st and 2nd balanced signal terminals 24 and 25 can be suppressed, the deterioration of differential attenuation amount and differential isolation can also be suppressed.
  • the comb electrode of the IDT electrode connected to the first balanced signal terminal and the comb electrode of the IDT electrode connected to the second balanced signal terminal are the same ground electrode.
  • two currents having opposite phases flow through the grounding electrode pad and the wiring connected to the grounding electrode pad.
  • the balance between the first and second balanced signal terminals is deteriorated, and accordingly, the differential attenuation amount and the differential isolation are also deteriorated.
  • duplexer 1 of the present embodiment As a comparative example of the duplexer 1 of the present embodiment, a duplexer having the same configuration as the duplexer 1 of the present embodiment except that the receiver filter 300 shown in FIG. .
  • the attenuation characteristic between the unbalanced signal terminal 23 and each of the first and second balanced signal terminals 24 and 25, etc. was measured.
  • reception-side filter 300 shown in FIG. 4 has the same configuration as the reception-side filter 20 of the above-described embodiment except for the following (1) to (2).
  • the first comb-shaped electrode 41a of the IDT electrode 41 and the first comb-shaped electrode 61a of the IDT electrode 61 are connected to the ground electrode pad 27 in common.
  • the second comb-like electrode 31b of the IDT electrode 31 is connected to the ground electrode pad 29a, and the second comb-like electrode 51b of the IDT electrode 51 is connected to the ground electrode pad 29b.
  • FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal 10 and the first reception-side signal terminal 21 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 6 is a graph showing the attenuation characteristic between the antenna terminal 10 and the second reception-side signal terminal 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 7 is a graph showing the differential attenuation characteristics between the antenna terminal 10 and the first and second receiving signal terminals 21 and 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal 10 and the first reception-side signal terminal 21 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 6 is a graph showing the attenuation characteristic between the antenna terminal 10 and the second reception-side signal terminal 22 in the duplexer 1 of the present embodiment and the duplexer of the comparativ
  • FIG. 8 is a graph showing isolation characteristics between the transmission-side signal terminal 12 and the first reception-side signal terminal 21 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 9 is a graph showing the isolation characteristics between the transmission-side signal terminal 12 and the second reception-side signal terminal 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example.
  • FIG. 10 is a graph showing differential isolation characteristics between the transmission-side signal terminal 12 and the first and second reception-side signal terminals 21 and 22 in the duplexer 1 of this embodiment and the duplexer of the comparative example. is there.
  • a solid line indicates the present embodiment, and a dashed line indicates a comparative example.
  • Sdd1 (S31-S41) / ⁇ (2) 1/2 ⁇
  • Sdd2 (S32-S42) / ⁇ (2) 1/2 ⁇
  • Sdd1 differential attenuation
  • Sdd2 differential isolation
  • S31 S parameter from the antenna terminal 10 to the first receiving signal terminal 21
  • S41 S parameter from the antenna terminal 10 to the second receiving signal terminal 22
  • S32 S parameter from the transmission side signal terminal 12 to the first reception side signal terminal
  • S42 S parameter from the transmission side signal terminal 12 to the second reception side signal terminal 22, It is.
  • the duplexer of the comparative example in the pass band (824 MHz to 849 MHz) of the transmission side filter 13, the antenna terminal 10 and the first reception side signal terminal 21 are not connected.
  • the attenuation characteristic and the attenuation characteristic between the antenna terminal 10 and the second receiving signal terminal 22 are greatly different.
  • the attenuation characteristic between the antenna terminal 10 and the first reception side signal terminal 21 in the pass band (824 MHz to 849 MHz) of the transmission side filter 13, and the antenna terminal 10 And the second receiving side signal terminal 22 are relatively approximate to each other.
  • the duplexer 1 of the present embodiment has a larger differential attenuation in the pass band (824 MHz to 849 MHz) of the transmission-side filter 13 than the duplexer of the comparative example.
  • the duplexer of the comparative example in the pass band (824 MHz to 849 MHz) of the transmission filter 13, the transmission signal terminal 12 and the first reception signal terminal 21 are used. And the isolation characteristic between the transmission side signal terminal 12 and the second reception side signal terminal 22 are greatly different.
  • the isolation characteristics between the transmission side signal terminal 12 and the first reception side signal terminal 21 in the pass band (824 MHz to 849 MHz) of the transmission side filter 13 and the transmission The isolation characteristic between the side signal terminal 12 and the second reception side signal terminal 22 is relatively approximate.
  • the duplexer 1 of the present embodiment has a larger differential isolation in the pass band (824 MHz to 849 MHz) of the transmission-side filter 13 than the duplexer of the comparative example.
  • the first comb-shaped electrode 41a of the IDT electrode 41 connected to the first balanced signal terminal 24 and the first of the IDT electrode 61 connected to the second balanced signal terminal 25 are shown.
  • the differential attenuation and the differential isolation can be increased, and the balance between the first and second balanced signal terminals 24 and 25 can be increased. It can be seen that the deterioration of the degree can be suppressed.
  • the first comb-shaped electrode 41 a of the IDT electrode 41 and the first of the IDT electrode 61 among all the comb-shaped electrodes connected to the ground potential are used.
  • the comb-like electrodes 31b, 32a, 33a, 42b, 43b, 51b, 52a, 53a, 62b, and 63b, excluding the comb-like electrode 61a, are commonly connected to the ground electrode pad 27 formed on the piezoelectric substrate 26.
  • grounding can be enlarged as a whole filter.
  • deterioration of the out-of-band attenuation can be suppressed.
  • the present invention is not limited to this configuration.
  • the comb-like electrodes 31b, 32a, 33a, 42b, 43b, 51b, 52a, 53a, 62b, and 63b may be connected to a plurality of ground electrode pads.
  • Each of the ground electrode pads 29a and 29b is connected to lands and wirings formed on a mounting substrate on which the piezoelectric substrate 26 is mounted.
  • the land and wiring to which the grounding electrode pad 29a is connected and the land and wiring to which the grounding electrode pad 29b is connected may be connected to each other on the mounting board or may not be connected to each other.
  • Good that is, in the present invention, on the piezoelectric substrate to which the comb-like electrode connected to the ground potential of the two comb-like electrodes constituting the IDT electrode connected to the first balanced signal terminal is connected.
  • On the piezoelectric substrate to which the comb-like electrode connected to the ground potential of the two comb-like electrodes constituting the IDT electrode connected to the second balanced signal terminal is connected.
  • the circuit configuration on the mounting substrate is not particularly limited. This is because the balance between the first and second balanced signal terminals is reduced when currents in opposite phases are combined on the piezoelectric substrate, and the currents in opposite phases are reduced. This is because the balance between the first and second balanced signal terminals is unlikely to decrease unless they are combined together.
  • FIG. 11 is a schematic configuration diagram of a reception-side filter according to the first modification.
  • FIG. 12 is a schematic configuration diagram of a reception-side filter according to the second modification.
  • FIG. 13 is a schematic configuration diagram of a reception-side filter according to a third modification.
  • the elastic wave filter unit 28 includes the first to fourth longitudinally coupled resonator type elastic wave filter units 30, 40, 50, 60
  • the first longitudinally coupled resonator type acoustic wave filter unit 30 and the second longitudinally coupled resonator type acoustic wave filter unit 40 are cascade-connected.
  • the third longitudinally coupled resonator type acoustic wave filter unit 50 and the fourth longitudinally coupled resonator type acoustic wave filter unit 60 are connected in cascade.
  • the present invention is not limited to this configuration.
  • the elastic wave filter unit 28 may be constituted by second and fourth longitudinally coupled resonator type elastic wave filter units 40 and 60.
  • the elastic wave filter unit 28 may be constituted by one longitudinally coupled resonator type elastic wave filter unit.
  • the so-called 5IDT type longitudinally coupled resonator type acoustic wave filter in which the longitudinally coupled resonator type acoustic wave filter unit constituting the acoustic wave filter unit 28 has five IDT electrodes. It consists of parts.
  • the acoustic wave filter unit 28 includes five IDT electrodes 81 to 81 formed on the piezoelectric substrate 26 along the propagation direction of the acoustic wave. 85.
  • a pair of grating reflectors 86 and 87 are formed on both sides of the elastic wave propagation direction in the region where the IDT electrodes 81 to 85 are formed.
  • the IDT electrode 81 is located in the center of the IDT electrodes 81 to 85 in the elastic wave propagation direction.
  • the IDT electrode 81 includes first and second comb-like electrodes 81a and 81b.
  • the IDT electrode 82 is formed adjacent to the IDT electrode 81 in the propagation direction of the elastic wave.
  • the IDT electrode 82 includes first and second comb-like electrodes 82a and 82b.
  • the IDT electrode 83 is formed adjacent to the IDT electrode 81 in the elastic wave propagation direction.
  • the IDT electrode 83 includes first and second comb-like electrodes 83a and 83b.
  • the IDT electrode 84 is formed adjacent to the IDT electrode 82 in the propagation direction of the elastic wave.
  • the IDT electrode 84 includes first and second comb-like electrodes 84a and 84b.
  • the IDT electrode 85 is formed adjacent to the IDT electrode 83 in the elastic wave propagation direction.
  • the IDT electrode 85 includes first and second comb-like electrodes 85a and 85b.
  • the first comb-shaped electrode 81 a of the IDT electrode 81 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 81b of the IDT electrode 81 is connected to the ground electrode pad 27 connected to the ground potential.
  • the first comb-like electrode 82a of the IDT electrode 82 is connected to the ground electrode pad 29b connected to the ground potential.
  • the second comb-like electrode 82 b of the IDT electrode 82 is connected to the second balanced signal terminal 25.
  • the first comb-like electrode 83a of the IDT electrode 83 is connected to the ground electrode pad 29a connected to the ground potential.
  • the second comb-like electrode 83 b of the IDT electrode 83 is connected to the first balanced signal terminal 24.
  • the first comb-like electrode 84 a of the IDT electrode 84 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 84b of the IDT electrode 84 is connected to the ground electrode pad 27 connected to the ground potential.
  • the first comb-like electrode 85 a of the IDT electrode 85 is connected to the unbalanced signal terminal 23.
  • the second comb-like electrode 85b of the IDT electrode 85 is connected to the ground electrode pad 27 connected to the ground potential.
  • the IDT electrode 82 and the IDT electrode 83 are reversed with the direction orthogonal to the propagation direction of the acoustic wave as the axis of symmetry. Therefore, in the acoustic wave filter unit 28, the signal output from the first balanced signal terminal 24 and the signal output from the second balanced signal terminal 25 are in an opposite phase relationship.
  • the configurations of the IDT electrodes 81 to 85 and the grating reflectors 86 and 87 in this modification are substantially the same as the configurations of the IDT electrodes and the reflectors of the above embodiment.
  • the example which is a filter part was demonstrated.
  • the present invention is not limited to this configuration.
  • the longitudinally coupled resonator type acoustic wave filter portion constituting the acoustic wave filter unit 28 is a so-called 3IDT type longitudinally coupled resonator type acoustic wave filter having three IDT electrodes 81 to 83. Part.
  • FIG. 14 is a schematic configuration diagram of a reception-side filter according to a fourth modification.
  • the second comb-like electrode 41b of the IDT electrode 41 of the second longitudinally coupled resonator type acoustic wave filter unit 40 is connected to the first balanced signal terminal 24, and the IDT electrodes 42, 43 are connected.
  • the first comb-like electrodes 42a and 43a are connected to the unbalanced signal terminal 23 via the first longitudinally coupled resonator type acoustic wave filter unit 30 and the acoustic wave resonator 70, and the fourth
  • the second comb-like electrode 61b of the IDT electrode 61 of the longitudinally coupled resonator type acoustic wave filter unit 60 is connected to the second balanced signal terminal 25, and the first comb-like electrodes of the IDT electrodes 62 and 63 are connected.
  • the first comb-like electrode 41 a of the IDT electrode 41 of the second longitudinally coupled resonator type acoustic wave filter unit 40 is connected to the unbalanced signal terminal 23, and the IDT electrode 42. , 43 are connected to the first balanced signal terminal 24, and the first comb of the IDT electrode 61 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60 is connected to the first balanced signal terminal 24.
  • the tooth-shaped electrode 61 a may be connected to the unbalanced signal terminal 23, and the second comb-shaped electrodes 62 b and 63 b of the IDT electrodes 62 and 63 may be connected to the second balanced signal terminal 25.
  • the first comb-like electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24, and the IDT electrodes 62 and 43 connected to the second balanced signal terminal 25, 63 first comb-like electrodes 62a and 63a are connected to different grounding electrode pads.
  • the first comb-like electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24 are connected to the ground electrode pad 29a.
  • the first comb-like electrodes 62a and 63a of the IDT electrodes 62 and 63 connected to the second balanced signal terminal 25 are connected to the ground electrode pad 29b.
  • first comb-shaped electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24 may be connected to different grounding electrode pads.
  • first comb-like electrodes 62a and 63a of the IDT electrodes 62 and 63 connected to the second balanced signal terminal 25 may be connected to different grounding electrode pads.
  • FIG. 15 is a schematic cross-sectional view in which a part of the reception-side filter according to the fifth modification is enlarged.
  • FIG. 16 is a schematic cross-sectional view in which a part of the reception-side filter according to the sixth modification is enlarged.
  • the duplexer uses surface acoustic waves.
  • the present invention is not limited to this configuration.
  • the duplexer and the elastic wave filter according to the present invention may use boundary acoustic waves.
  • the reception-side filter is configured by a so-called two-medium type boundary acoustic wave filter 90.
  • the boundary acoustic wave filter 90 includes a piezoelectric substrate 26 as a first medium layer and a dielectric layer 91 as a second medium layer stacked on the piezoelectric substrate 26.
  • An electrode 92 is formed at the boundary between the piezoelectric substrate 26 and the dielectric layer 91.
  • Each electrode 92 constitutes each IDT electrode, reflector, and the like.
  • the reception-side filter is constituted by a so-called three-medium boundary acoustic wave filter 93.
  • the boundary acoustic wave filter 93 includes a piezoelectric substrate 26 as a first medium layer, a dielectric layer 94 as a second medium layer formed on the piezoelectric substrate 26, and the piezoelectric substrate 26 and the dielectric layer. 94, and a dielectric layer 95 serving as a third medium layer.
  • An electrode 92 is formed at the boundary between the piezoelectric substrate 26 and the dielectric layer 95.
  • Each electrode 92 constitutes each IDT electrode, reflector, and the like.
  • the dielectric layer 95 is made of a material having a slower transverse sound speed than the piezoelectric substrate 26 and the dielectric layer 94. For this reason, the boundary acoustic wave generated by the IDT electrode constituted by the electrode 92 is effectively confined in the dielectric layer 95.
  • the piezoelectric substrate 26 can be configured by, for example, a LiNbO 3 substrate having Y cut X propagation and Euler angles (0 °, 105 °, 0 °).
  • the dielectric layer 94 can be composed of, for example, a SiN layer.
  • the dielectric layers 91 and 95 can be composed of, for example, a SiO 2 layer.
  • the IDT electrode is preferably formed of at least one of Cu, Ag and Au, which is a metal having a higher density than Al, or an alloy containing one or more of these metals.
  • duplexer which is a type of duplexer
  • the duplexer is not limited to a duplexer.
  • the duplexer may be, for example, a triplexer.
  • the reception filter of the duplexer is configured by a longitudinally coupled resonator type elastic wave filter having a balance-unbalance conversion function
  • the transmission side filter is configured by a ladder type elastic wave filter.
  • the present invention is not limited to this configuration.
  • the duplexer according to the present invention if at least one of the plurality of filters constituting the duplexer is configured by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention.
  • both the transmission side filter and the reception side filter may be constituted by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention.
  • only the reception side filter may be constituted by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention.

Abstract

Disclosed is an acoustic wave filter having a balun conversion function, wherein deterioration of balance of signals between balanced signal terminals is suppressed. A receiving side filter (20) is provided with an unbalanced signal terminal (23); first and second balanced signal terminals (24 and 25); a piezoelectric substrate (26); an acoustic wave filter unit (28) connected between the unbalanced signal terminal (23) and the first and second balanced signal terminals (24 and 25) upon the piezoelectric substrate (26); and first and second grounding electrode pads (29a and 29b) connected to a ground potential and formed upon the piezoelectric substrate (26). The acoustic wave filter unit (28) has an IDT electrode (41) connected to the first balanced signal terminal (24) and an IDT electrode (61) connected to the second balanced signal terminal (25). A first interdigital electrode (41a) of the IDT electrode (41) is connected to the grounding electrode pad (29a), and the first interdigital electrode (61a) of the IDT electrode (61) is connected to the grounding electrode pad (29b).

Description

弾性波フィルタ及び分波器Elastic wave filter and duplexer
　本発明は、弾性波フィルタ及び分波器に関する。より詳細には、本発明は、第１及び第２の平衡信号端子を備え、平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタ及び分波器に関する。 The present invention relates to an elastic wave filter and a duplexer. More specifically, the present invention relates to a longitudinally coupled resonator-type elastic wave filter and a duplexer having first and second balanced signal terminals and having a balanced-unbalanced conversion function.
　従来、例えば、下記の特許文献１などにおいて、携帯電話機などの通信機におけるＲＦ（Ｒａｄｉｏ　Ｆｒｅｑｕｅｎｃｙ）回路の帯域通過フィルタなどとして、弾性表面波や弾性境界波を利用した弾性波フィルタが種々提案されている。 Conventionally, for example, in Patent Document 1 below, various acoustic wave filters using surface acoustic waves or boundary acoustic waves have been proposed as bandpass filters for RF (Radio Frequency) circuits in communication devices such as mobile phones. Yes.
　図１７は、下記の特許文献１に記載の縦結合共振子型弾性表面波フィルタの模式的平面図である。図１７に示すように、縦結合共振子型弾性表面波フィルタ１００は、弾性表面波の伝搬方向に沿って形成されている第１～第３のＩＤＴ電極１０１～１０３を備えている。第１～第３のＩＤＴ電極１０１～１０３は、それぞれ１組のくし歯状電極からなる。第２のＩＤＴ電極１０２の一方側のくし歯状電極は、不平衡信号端子１０６に接続されており、他方側のくし歯状電極は、グラウンド電位に接続されている。第１及び第３のＩＤＴ電極１０１，１０３の一方側のくし歯状電極は、グラウンド電位に接続されており、他方側のくし歯状電極は、第１または第２の平衡信号端子１０７，１０８に接続されている。弾性表面波の伝搬方向において、第１～第３のＩＤＴ電極１０１～１０３が形成されている領域の両側には、反射器１０４，１０５が形成されている。 FIG. 17 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1 below. As shown in FIG. 17, the longitudinally coupled resonator type surface acoustic wave filter 100 includes first to third IDT electrodes 101 to 103 formed along the propagation direction of the surface acoustic wave. Each of the first to third IDT electrodes 101 to 103 is composed of a pair of comb-like electrodes. The comb-like electrode on one side of the second IDT electrode 102 is connected to the unbalanced signal terminal 106, and the comb-like electrode on the other side is connected to the ground potential. The comb-like electrodes on one side of the first and third IDT electrodes 101 and 103 are connected to the ground potential, and the comb-like electrodes on the other side are the first or second balanced signal terminals 107 and 108. It is connected to the. Reflectors 104 and 105 are formed on both sides of the region where the first to third IDT electrodes 101 to 103 are formed in the propagation direction of the surface acoustic wave.
　縦結合共振子型弾性表面波フィルタ１００は、第１の平衡信号端子１０７から出力される信号と、第２の平衡信号端子１０８から出力される信号とが互いに逆相の関係となるように構成されている。すなわち、第１のＩＤＴ電極１０１は、第３のＩＤＴ電極１０３を反転した構成となっている。このため、縦結合共振子型弾性表面波フィルタ１００は、平衡－不平衡変換機能を有している。 The longitudinally coupled resonator type surface acoustic wave filter 100 is configured such that the signal output from the first balanced signal terminal 107 and the signal output from the second balanced signal terminal 108 are in opposite phase to each other. Has been. That is, the first IDT electrode 101 has a configuration obtained by inverting the third IDT electrode 103. Therefore, the longitudinally coupled resonator type surface acoustic wave filter 100 has a balance-unbalance conversion function.
　また、特許文献１には、上記図１７に示す縦結合共振子型弾性表面波フィルタ１００とは異なる縦結合共振子型弾性表面波フィルタも開示されている。その縦結合共振子型弾性表面波フィルタの模式的平面図を図１８に示す。図１８に示すように、縦結合共振子型弾性表面波フィルタ２００は、４つの縦結合共振子型弾性表面波フィルタ部２０１～２０４を備えている。縦結合共振子型弾性表面波フィルタ部２０１～２０４のそれぞれは、弾性表面波の伝搬方向に沿って形成されている３つのＩＤＴ電極を備えている。それら３つのＩＤＴ電極が形成されている領域の弾性表面波の伝搬方向における両側には、一対の反射器が形成されている。縦結合共振子型弾性表面波フィルタ部２０１～２０４のＩＤＴ電極は、それぞれ１組のくし歯状電極からなる。縦結合共振子型弾性表面波フィルタ部２０１，２０２のそれぞれの弾性表面波の伝搬方向における中央に位置するＩＤＴ電極の一方側のくし歯状電極は、不平衡信号端子２０５に共通に接続されており、他方側のくし歯状電極は、グラウンド電位に接続されている。縦結合共振子型弾性表面波フィルタ部２０１，２０２のそれぞれの弾性表面波の伝搬方向における両側に位置するＩＤＴ電極の一方側のくし歯状電極は、グラウンド電位に接続されており、他方側のくし歯状電極は、縦結合共振子型弾性表面波フィルタ部２０３，２０４のそれぞれの弾性表面波の伝搬方向における両側に位置するＩＤＴ電極の一方側のくし歯状電極に接続されている。縦結合共振子型弾性表面波フィルタ部２０３，２０４のそれぞれの弾性表面波の伝搬方向における両側に位置するＩＤＴ電極の他方側のくし歯状電極は、グラウンド電位に接続されている。縦結合共振子型弾性表面波フィルタ部２０３，２０４のそれぞれの弾性表面波の伝搬方向における中央に位置するＩＤＴ電極の一方側のくし歯状電極は、グラウンド電位に接続されており、他方側のくし歯状電極は、第１または第２の平衡信号端子２０６，２０７に接続されている。縦結合共振子型弾性表面波フィルタ２００は、第１の平衡信号端子２０６から出力される信号と、第２の平衡信号端子２０７から出力される信号とが互いに逆相の関係となるように構成されている。すなわち、縦結合共振子型弾性表面波フィルタ部２０３の弾性表面波の伝搬方向における中央に位置するＩＤＴ電極は、縦結合共振子型弾性表面波フィルタ部２０４の弾性表面波の伝搬方向における中央に位置するＩＤＴ電極を反転した構成となっている。このため、縦結合共振子型弾性表面波フィルタ２００は、上記縦結合共振子型弾性表面波フィルタ１００と同様に、平衡－不平衡変換機能を有している。 Also, Patent Document 1 discloses a longitudinally coupled resonator type surface acoustic wave filter different from the longitudinally coupled resonator type surface acoustic wave filter 100 shown in FIG. A schematic plan view of the longitudinally coupled resonator type surface acoustic wave filter is shown in FIG. As shown in FIG. 18, the longitudinally coupled resonator type surface acoustic wave filter 200 includes four longitudinally coupled resonator type surface acoustic wave filter units 201 to 204. Each of the longitudinally coupled resonator-type surface acoustic wave filter sections 201 to 204 includes three IDT electrodes formed along the propagation direction of the surface acoustic wave. A pair of reflectors is formed on both sides in the propagation direction of the surface acoustic wave in the region where the three IDT electrodes are formed. The IDT electrodes of the longitudinally coupled resonator type surface acoustic wave filter portions 201 to 204 are each composed of a pair of comb-like electrodes. The comb-like electrode on one side of the IDT electrode located in the center in the propagation direction of the surface acoustic waves of each of the longitudinally coupled resonator type surface acoustic wave filter units 201 and 202 is connected in common to the unbalanced signal terminal 205. The comb electrode on the other side is connected to the ground potential. The comb-like electrodes on one side of the IDT electrodes located on both sides in the propagation direction of the surface acoustic waves of the longitudinally coupled resonator type surface acoustic wave filter units 201 and 202 are connected to the ground potential, and the other side The comb-like electrode is connected to the comb-like electrode on one side of the IDT electrode located on both sides of the longitudinally coupled resonator-type surface acoustic wave filter sections 203 and 204 in the propagation direction of the respective surface acoustic waves. The comb-like electrodes on the other side of the IDT electrodes located on both sides in the propagation direction of the surface acoustic waves of the longitudinally coupled resonator type surface acoustic wave filter sections 203 and 204 are connected to the ground potential. The comb-like electrode on one side of the IDT electrode located at the center in the propagation direction of the surface acoustic waves of each of the longitudinally coupled resonator type surface acoustic wave filter sections 203 and 204 is connected to the ground potential, and the other side The comb-like electrode is connected to the first or second balanced signal terminal 206 or 207. The longitudinally coupled resonator type surface acoustic wave filter 200 is configured such that the signal output from the first balanced signal terminal 206 and the signal output from the second balanced signal terminal 207 are in opposite phase to each other. Has been. That is, the IDT electrode located at the center in the propagation direction of the surface acoustic wave of the longitudinally coupled resonator type surface acoustic wave filter unit 203 is located at the center in the propagation direction of the surface acoustic wave of the longitudinally coupled resonator type surface acoustic wave filter unit 204 The IDT electrode positioned is inverted. For this reason, the longitudinally coupled resonator type surface acoustic wave filter 200 has a balanced-unbalanced conversion function, like the longitudinally coupled resonator type surface acoustic wave filter 100.
特開２００６－１３６００５号公報JP 2006-136005 A
　図１７及び図１８に示すような縦結合共振子型弾性表面波フィルタ１００，２００では、通常、圧電基板の上に、上記ＩＤＴ電極や反射器を構成する電極と共に、グラウンド電位に接続される接地用電極パッドが形成されている。そして、ＩＤＴ電極のグラウンド電位に接続される側のくし歯状電極が、接地用電極パッドに接続されている。通常、小型化を実現するために、接地用電極パッドの数量は、ＩＤＴ電極の数量よりも少なくされている。この場合、複数のＩＤＴ電極がひとつの接地用電極パッドに共通に接続される。例えば、図１７においては、第１のＩＤＴ電極１０１の一方側のくし歯状電極と、第３のＩＤＴ電極１０３の一方側のくし歯状電極とが、共通の接地用電極パッドに接続されることもあった。 In the longitudinally coupled resonator type surface acoustic wave filters 100 and 200 as shown in FIGS. 17 and 18, the ground is usually connected to the ground potential together with the electrodes constituting the IDT electrode and the reflector on the piezoelectric substrate. An electrode pad is formed. The comb-like electrode on the side connected to the ground potential of the IDT electrode is connected to the ground electrode pad. Usually, in order to realize miniaturization, the number of grounding electrode pads is made smaller than the number of IDT electrodes. In this case, a plurality of IDT electrodes are commonly connected to one ground electrode pad. For example, in FIG. 17, the comb-like electrode on one side of the first IDT electrode 101 and the comb-like electrode on one side of the third IDT electrode 103 are connected to a common ground electrode pad. There was also.
　しかしながら、本発明者は、平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタにおいて、複数のＩＤＴ電極を、ひとつの接地用電極パッドに共通に接続した場合、第１及び第２の平衡信号端子間における信号の平衡度が悪化する場合があることを見出した。 However, in the longitudinally coupled resonator type acoustic wave filter having a balanced-unbalanced conversion function, the present inventor, when a plurality of IDT electrodes are commonly connected to one ground electrode pad, It has been found that the balance of signals between balanced signal terminals may deteriorate.
　本発明は、かかる点に鑑みてなされたものであり、その目的は、平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタにおいて、平衡信号端子間の信号の平衡度の悪化を抑制することにある。 The present invention has been made in view of such points, and an object of the present invention is to suppress deterioration of the balance of signals between balanced signal terminals in a longitudinally coupled resonator type elastic wave filter having a balanced-unbalanced conversion function. There is to do.
　本発明者は、鋭意研究の結果、平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタに関して、以下のことを見出した。すなわち、第１の平衡信号端子に接続されているＩＤＴ電極の一方側のくし歯状電極と、第２の平衡信号端子に接続されているＩＤＴ電極の一方側のくし歯状電極とを、共通の接地用電極パッドに接続した場合に、第１及び第２の平衡信号端子間の信号の平衡度が悪化することを見出した。また、本発明者は、その原因が、第１の平衡信号端子に接続されているＩＤＴ電極の一方側のくし歯状電極と、第２の平衡信号端子に接続されているＩＤＴ電極の一方側のくし歯状電極とを、共通の接地用電極パッドに接続したことにより、逆相の関係にある２つの電流が圧電基板上で合わさることにあることを見出した。その結果、本発明者は、本発明をなすに至った。 As a result of diligent research, the present inventor has found the following regarding a longitudinally coupled resonator type elastic wave filter having a balanced-unbalanced conversion function. That is, a comb-like electrode on one side of the IDT electrode connected to the first balanced signal terminal and a comb-like electrode on one side of the IDT electrode connected to the second balanced signal terminal are shared. It has been found that the signal balance between the first and second balanced signal terminals deteriorates when connected to the grounding electrode pad. Further, the inventor of the present invention is caused by a comb-like electrode on one side of the IDT electrode connected to the first balanced signal terminal and one side of the IDT electrode connected to the second balanced signal terminal. It has been found that by connecting the comb-like electrode to a common ground electrode pad, two currents in a reverse phase are combined on the piezoelectric substrate. As a result, the inventor has made the present invention.
　すなわち、本発明に係る弾性波フィルタは、不平衡信号端子と、第１及び第２の平衡信号端子と、圧電基板と、圧電基板上において、不平衡信号端子と第１及び第２の平衡信号端子との間に接続されている弾性波フィルタ部と、圧電基板上に形成されており、グラウンド電位に接続されている第１及び第２の接地用電極パッドとを備え、弾性波フィルタ部は、圧電基板上に形成された複数のＩＤＴ電極からなり、複数のＩＤＴ電極のうち、少なくとも一つのＩＤＴ電極は、不平衡信号端子に接続されている少なくとも一つのくし歯状電極を有する不平衡信号端子側ＩＤＴ電極であり、複数のＩＤＴ電極のうちの少なくとも一つのＩＤＴ電極は、第１の平衡信号端子に接続されている少なくとも一つのくし歯状電極と、第１の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する第１の平衡信号端子側ＩＤＴ電極であり、複数のＩＤＴ電極のうちの少なくとも一つのＩＤＴ電極は、第２の平衡信号端子に接続されている少なくとも一つのくし歯状電極と、第２の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する第２の平衡信号端子側ＩＤＴ電極であり、第１の平衡信号端子側ＩＤＴ電極と、第２の平衡信号端子側ＩＤＴ電極とは、弾性波の伝搬方向に直行する方向を対称軸として、反転した構成とされている。 That is, the acoustic wave filter according to the present invention includes an unbalanced signal terminal, first and second balanced signal terminals, a piezoelectric substrate, and the unbalanced signal terminal and the first and second balanced signals on the piezoelectric substrate. An elastic wave filter unit connected between the terminals and a first and a second grounding electrode pad formed on the piezoelectric substrate and connected to the ground potential. The unbalanced signal includes a plurality of IDT electrodes formed on the piezoelectric substrate, and at least one of the plurality of IDT electrodes has at least one comb-like electrode connected to the unbalanced signal terminal. It is a terminal-side IDT electrode, and at least one IDT electrode of the plurality of IDT electrodes includes at least one comb-like electrode connected to the first balanced signal terminal and a first ground electrode pad. A first balanced signal terminal-side IDT electrode having at least one comb-like electrode connected to the at least one IDT electrode, wherein at least one IDT electrode of the plurality of IDT electrodes is connected to the second balanced signal terminal. A first balanced signal terminal-side IDT electrode having at least one comb-like electrode and at least one comb-like electrode connected to the second ground electrode pad, The terminal-side IDT electrode and the second balanced signal terminal-side IDT electrode are configured to be reversed with the direction orthogonal to the propagation direction of the acoustic wave as the axis of symmetry.
　本発明に係る弾性波フィルタのある特定の局面では、圧電基板上に形成されており、グラウンド電位に接続されている第３の接地用電極パッドをさらに備え、複数のＩＤＴ電極のうち、第１の平衡信号端子側ＩＤＴ電極と第２の平衡信号端子側ＩＤＴ電極以外のＩＤＴ電極は、第３の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する。 In a specific aspect of the acoustic wave filter according to the present invention, the elastic wave filter further includes a third grounding electrode pad formed on the piezoelectric substrate and connected to the ground potential, and the first of the plurality of IDT electrodes. The IDT electrodes other than the balanced signal terminal side IDT electrode and the second balanced signal terminal side IDT electrode have at least one comb-like electrode connected to the third ground electrode pad.
　本発明に係る分波器は、上記本発明に係る弾性波フィルタを備えている。 The duplexer according to the present invention includes the elastic wave filter according to the present invention.
　本発明では、第１の平衡信号端子側ＩＤＴ電極の一方側のくし歯状電極と、第２の平衡信号端子側ＩＤＴ電極の一方側のくし歯状電極とが異なる接地用電極パッドに接続されている。このため、互いに逆相の関係にある、第１の平衡信号端子側ＩＤＴ電極を流れる電流と、第２の平衡信号端子側ＩＤＴ電極を流れる電流とが圧電基板上で合わさることを抑制できる。その結果、第１及び第２の平衡信号端子間の信号の平衡度の悪化を抑制することができる。 In the present invention, the comb-like electrode on one side of the first balanced signal terminal side IDT electrode and the comb-like electrode on one side of the second balanced signal terminal side IDT electrode are connected to different ground electrode pads. ing. For this reason, it can suppress that the electric current which flows through the 1st balanced signal terminal side IDT electrode and the electric current which flows through the 2nd balanced signal terminal side IDT electrode which are in a mutually reverse phase relationship match on a piezoelectric substrate. As a result, it is possible to suppress deterioration in the degree of balance of the signal between the first and second balanced signal terminals.
図１は、本発明を実施した一実施形態に係るデュプレクサの模式図である。FIG. 1 is a schematic diagram of a duplexer according to an embodiment of the present invention. 図２は、本発明を実施した一実施形態における受信側フィルタの模式的平面図である。FIG. 2 is a schematic plan view of a reception-side filter according to one embodiment of the present invention. 図３は、本発明を実施した一実施形態における受信側フィルタの略図的平面図である。FIG. 3 is a schematic plan view of a receiving filter according to an embodiment of the present invention. 図４は、比較例における受信側フィルタの略図的平面図である。FIG. 4 is a schematic plan view of a reception-side filter in the comparative example. 図５は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、アンテナ端子と第１の受信側信号端子との間の減衰量特性を表すグラフである。図５において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal and the first reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example. In FIG. 5, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図６は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、アンテナ端子と第２の受信側信号端子との間の減衰量特性を表すグラフである。図６において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 6 is a graph showing the attenuation characteristic between the antenna terminal and the second reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example. In FIG. 6, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図７は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、アンテナ端子と第１及び第２の受信側信号端子との間の差動減衰量特性を表すグラフである。図７において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 7 is a graph showing the differential attenuation characteristic between the antenna terminal and the first and second receiving-side signal terminals in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example. In FIG. 7, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図８は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、送信側信号端子と第１の受信側信号端子との間のアイソレーション特性を表すグラフである。図８において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 8 is a graph showing the isolation characteristics between the transmission-side signal terminal and the first reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example. In FIG. 8, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図９は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、送信側信号端子と第２の受信側信号端子との間のアイソレーション特性を表すグラフである。図９において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 9 is a graph showing the isolation characteristics between the transmission-side signal terminal and the second reception-side signal terminal in the duplexer of one embodiment implementing the present invention and the duplexer of the comparative example. In FIG. 9, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図１０は、本発明を実施した一実施形態のデュプレクサと比較例のデュプレクサとにおける、送信側信号端子と第１及び第２の受信側信号端子との間の差動アイソレーション特性を表すグラフである。図１０において、実線が本発明を実施した一実施形態を示し、一点破線が比較例を示している。FIG. 10 is a graph showing the differential isolation characteristics between the transmission-side signal terminal and the first and second reception-side signal terminals in the duplexer according to the embodiment of the present invention and the duplexer according to the comparative example. is there. In FIG. 10, a solid line indicates an embodiment in which the present invention is implemented, and a dashed line indicates a comparative example. 図１１は、第１の変形例に係る受信側フィルタの模式的構成図である。FIG. 11 is a schematic configuration diagram of a reception-side filter according to the first modification. 図１２は、第２の変形例に係る受信側フィルタの模式的構成図である。FIG. 12 is a schematic configuration diagram of a reception-side filter according to the second modification. 図１３は、第３の変形例に係る受信側フィルタの模式的構成図である。FIG. 13 is a schematic configuration diagram of a reception-side filter according to a third modification. 図１４は、第４の変形例に係る受信側フィルタの模式的構成図である。FIG. 14 is a schematic configuration diagram of a reception-side filter according to a fourth modification. 図１５は、第５の変形例に係る受信側フィルタの一部分を拡大した略図的断面図である。FIG. 15 is a schematic cross-sectional view in which a part of the reception-side filter according to the fifth modification is enlarged. 図１６は、第６の変形例に係る受信側フィルタの一部分を拡大した略図的断面図である。FIG. 16 is a schematic cross-sectional view in which a part of the reception-side filter according to the sixth modification is enlarged. 図１７は、特許文献１に記載の縦結合共振子型弾性表面波フィルタの模式的平面図である。FIG. 17 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1. 図１８は、特許文献１に記載の、図１７に示す縦結合共振子型弾性表面波フィルタとは異なる縦結合共振子型弾性表面波フィルタの模式的平面図である。FIG. 18 is a schematic plan view of a longitudinally coupled resonator type surface acoustic wave filter described in Patent Document 1, which is different from the longitudinally coupled resonator type surface acoustic wave filter shown in FIG.
　以下、本発明を実施した好ましい形態について、図１に示すデュプレクサ１を例に挙げて説明する。但し、図１に示すデュプレクサ１は、単なる例示である。本発明は、デュプレクサ１に何ら限定されない。 Hereinafter, preferred embodiments of the present invention will be described by taking the duplexer 1 shown in FIG. 1 as an example. However, the duplexer 1 shown in FIG. 1 is merely an example. The present invention is not limited to the duplexer 1.
　図１に示すデュプレクサ１は、ＵＭＴＳ（Ｕｎｉｖｅｒｓａｌ　Ｍｏｂｉｌｅ　Ｔｅｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓ　Ｓｙｓｔｅｍ）－ＢＡＮＤ５に対応するデュプレクサである。なお、ＵＭＴＳ－ＢＡＮＤ５の受信側フィルタの通過帯域は、８６９ＭＨｚ～８９４ＭＨｚである。ＵＭＴＳ－ＢＡＮＤ５の送信側フィルタの通過帯域は、８２４ＭＨｚ～８４９ＭＨｚである。 The duplexer 1 shown in FIG. 1 is a duplexer corresponding to UMTS (Universal Mobile Telecommunications System) -BAND5. Note that the pass band of the reception-side filter of UMTS-BAND5 is 869 MHz to 894 MHz. The pass band of the transmission side filter of UMTS-BAND5 is 824 MHz to 849 MHz.
　図１に示すように、デュプレクサ１は、アンテナ端子１０と、送信側信号端子１２と、第１及び第２の受信側信号端子２１，２２とを備えている。アンテナ端子１０は、デュプレクサ１が搭載される通信機のアンテナ（Ａｎｔ．）に接続されている。アンテナ（Ａｎｔ．）とアンテナ端子１０との間の接続点と、グラウンド電位との間には、整合用インダクタ１１が接続されている。なお、本実施形態では、整合用インダクタ１１は、チップインダクタにより構成されているが、整合用インダクタ１１は、チップインダクタ以外のインダクタにより構成されていてもよい。 As shown in FIG. 1, the duplexer 1 includes an antenna terminal 10, a transmission-side signal terminal 12, and first and second reception- side signal terminals 21 and 22. The antenna terminal 10 is connected to an antenna (Ant.) Of a communication device on which the duplexer 1 is mounted. A matching inductor 11 is connected between a connection point between the antenna (Ant.) And the antenna terminal 10 and the ground potential. In the present embodiment, the matching inductor 11 is configured by a chip inductor. However, the matching inductor 11 may be configured by an inductor other than the chip inductor.
　アンテナ端子１０と、送信側信号端子１２との間には、送信側フィルタ１３が接続されている。本実施形態では、送信側フィルタ１３は、弾性表面波や弾性境界波を利用したラダー型の弾性波フィルタである。但し、本発明において、送信側フィルタは、ラダー型の弾性波フィルタに限定されない。送信側フィルタは、例えば、縦結合共振子型弾性波フィルタであってもよい。 A transmission-side filter 13 is connected between the antenna terminal 10 and the transmission-side signal terminal 12. In the present embodiment, the transmission filter 13 is a ladder-type elastic wave filter using a surface acoustic wave or a boundary acoustic wave. However, in the present invention, the transmission-side filter is not limited to a ladder-type elastic wave filter. The transmission filter may be, for example, a longitudinally coupled resonator type elastic wave filter.
　一方、アンテナ端子１０と、第１及び第２の受信側信号端子２１，２２との間には、受信側フィルタ２０が接続されている。 On the other hand, a reception-side filter 20 is connected between the antenna terminal 10 and the first and second reception- side signal terminals 21 and 22.
　図２は、受信側フィルタ２０の模式的平面図である。図３は、受信側フィルタ２０の略図的平面図である。なお、描画の便宜上、図２及び下記の図１１、１２では、反射器を、内部に「×」を附した矩形として略図的に描画している。また、図３及び下記の図４では、反射器及びＩＤＴ電極を、共に、内部に「×」を附した四辺形として略図的に描画している。また、描画の便宜上、図２等において、電極指等の本数は、実際よりも少なく描画されている。 FIG. 2 is a schematic plan view of the reception-side filter 20. FIG. 3 is a schematic plan view of the reception filter 20. For convenience of drawing, in FIG. 2 and FIGS. 11 and 12 below, the reflector is schematically drawn as a rectangle with “x” inside. Further, in FIG. 3 and FIG. 4 below, both the reflector and the IDT electrode are schematically drawn as quadrilaterals with “x” inside. Further, for convenience of drawing, in FIG. 2 and the like, the number of electrode fingers and the like is drawn less than the actual number.
　図１～図３に示す受信側フィルタ２０は、弾性表面波や弾性境界波を利用した弾性波フィルタである。以下、本実施形態では、受信側フィルタ２０が弾性表面波を利用した弾性表面波フィルタである例について説明する。 The receiving side filter 20 shown in FIGS. 1 to 3 is an elastic wave filter using a surface acoustic wave or a boundary acoustic wave. Hereinafter, in the present embodiment, an example in which the reception-side filter 20 is a surface acoustic wave filter using surface acoustic waves will be described.
　図１～図３に示すように、受信側フィルタ２０は、不平衡信号端子２３と、第１及び第２の平衡信号端子２４，２５とを備えている。図１に示すように、不平衡信号端子２３は、アンテナ端子１０に接続されている。第１の平衡信号端子２４は、第１の受信側信号端子２１に接続されている。第２の平衡信号端子２５は、第２の受信側信号端子２２に接続されている。 As shown in FIGS. 1 to 3, the reception-side filter 20 includes an unbalanced signal terminal 23 and first and second balanced signal terminals 24 and 25. As shown in FIG. 1, the unbalanced signal terminal 23 is connected to the antenna terminal 10. The first balanced signal terminal 24 is connected to the first receiving signal terminal 21. The second balanced signal terminal 25 is connected to the second receiving signal terminal 22.
　図２に示すように、不平衡信号端子２３と、第１及び第２の平衡信号端子２４，２５との間には、圧電基板２６上に形成された弾性波フィルタ部２８が形成されている。弾性波フィルタ部２８は、平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタ部である。弾性波フィルタ部２８は、第１～第４の縦結合共振子型弾性波フィルタ部３０，４０，５０，６０により構成されている。 As shown in FIG. 2, an elastic wave filter unit 28 formed on the piezoelectric substrate 26 is formed between the unbalanced signal terminal 23 and the first and second balanced signal terminals 24 and 25. . The elastic wave filter unit 28 is a longitudinally coupled resonator type elastic wave filter unit having a balanced-unbalanced conversion function. The elastic wave filter unit 28 includes first to fourth longitudinally coupled resonator type elastic wave filter units 30, 40, 50 and 60.
　なお、圧電基板２６は、例えば、ＬｉＮｂＯ３基板やＬｉＴａＯ３基板などの圧電単結晶基板などにより形成することができる。 The piezoelectric substrate 26 can be formed by a piezoelectric single crystal substrate such as a LiNbO 3 substrate or a LiTaO 3 substrate, for example.
　図２及び図３に示すように、第１及び第２の縦結合共振子型弾性波フィルタ部３０，４０は、不平衡信号端子２３と、第１の平衡信号端子２４との間に接続されている。そして、第１の縦結合共振子型弾性波フィルタ部３０は、第２の縦結合共振子型弾性波フィルタ部４０と縦続接続されている。 As shown in FIGS. 2 and 3, the first and second longitudinally coupled resonator type acoustic wave filter units 30 and 40 are connected between the unbalanced signal terminal 23 and the first balanced signal terminal 24. ing. The first longitudinally coupled resonator type acoustic wave filter unit 30 is cascade-connected to the second longitudinally coupled resonator type acoustic wave filter unit 40.
　図２及び図３に示すように、第１の縦結合共振子型弾性波フィルタ部３０は、圧電基板２６上に、弾性波の伝搬方向に沿って形成されている３つのＩＤＴ電極３１～３３を備えている。圧電基板２６上において、ＩＤＴ電極３１～３３が形成されている領域の弾性波の伝搬方向の両側には、一対のグレーティング反射器３４，３５が形成されている。 As shown in FIGS. 2 and 3, the first longitudinally coupled resonator type elastic wave filter unit 30 includes three IDT electrodes 31 to 33 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 34 and 35 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 31 to 33 are formed.
　ＩＤＴ電極３１は、ＩＤＴ電極３１～３３のうち、弾性波の伝搬方向における中央に位置している。ＩＤＴ電極３１は、第１及び第２のくし歯状電極３１ａ，３１ｂを備えている。ＩＤＴ電極３２は、弾性波の伝搬方向において、ＩＤＴ電極３１に隣接して形成されている。ＩＤＴ電極３２は、第１及び第２のくし歯状電極３２ａ，３２ｂを備えている。ＩＤＴ電極３３は、弾性波の伝搬方向において、ＩＤＴ電極３１に隣接して形成されている。ＩＤＴ電極３３は、第１及び第２のくし歯状電極３３ａ，３３ｂを備えている。 The IDT electrode 31 is located in the center of the IDT electrodes 31 to 33 in the propagation direction of the elastic wave. The IDT electrode 31 includes first and second comb- like electrodes 31a and 31b. The IDT electrode 32 is formed adjacent to the IDT electrode 31 in the propagation direction of the elastic wave. The IDT electrode 32 includes first and second comb- like electrodes 32a and 32b. The IDT electrode 33 is formed adjacent to the IDT electrode 31 in the propagation direction of the elastic wave. The IDT electrode 33 includes first and second comb- like electrodes 33a and 33b.
　図２及び図３に示すように、第２の縦結合共振子型弾性波フィルタ部４０は、圧電基板２６上に、弾性波の伝搬方向に沿って形成されている３つのＩＤＴ電極４１～４３を備えている。圧電基板２６上において、ＩＤＴ電極４１～４３が形成されている領域の弾性波の伝搬方向の両側には、一対のグレーティング反射器４４，４５が形成されている。 As shown in FIGS. 2 and 3, the second longitudinally coupled resonator type acoustic wave filter unit 40 has three IDT electrodes 41 to 43 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 44 and 45 are formed on both sides in the elastic wave propagation direction in the region where the IDT electrodes 41 to 43 are formed.
　ＩＤＴ電極４１は、ＩＤＴ電極４１～４３のうち、弾性波の伝搬方向における中央に位置している。ＩＤＴ電極４１は、第１及び第２のくし歯状電極４１ａ，４１ｂを備えている。ＩＤＴ電極４２は、弾性波の伝搬方向において、ＩＤＴ電極４１に隣接して形成されている。ＩＤＴ電極４２は、第１及び第２のくし歯状電極４２ａ，４２ｂを備えている。ＩＤＴ電極４３は、弾性波の伝搬方向において、ＩＤＴ電極４１に隣接して形成されている。ＩＤＴ電極４３は、第１及び第２のくし歯状電極４３ａ，４３ｂを備えている。 The IDT electrode 41 is located in the center of the IDT electrodes 41 to 43 in the propagation direction of the elastic wave. The IDT electrode 41 includes first and second comb- like electrodes 41a and 41b. The IDT electrode 42 is formed adjacent to the IDT electrode 41 in the propagation direction of the elastic wave. The IDT electrode 42 includes first and second comb- like electrodes 42a and 42b. The IDT electrode 43 is formed adjacent to the IDT electrode 41 in the propagation direction of the elastic wave. The IDT electrode 43 includes first and second comb- like electrodes 43a and 43b.
　図２及び図３に示すように、ＩＤＴ電極３１の第１のくし歯状電極３１ａは、不平衡信号端子２３に接続されている。ＩＤＴ電極３１の第２のくし歯状電極３１ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極３２の第１のくし歯状電極３２ａは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極３２の第２のくし歯状電極３２ｂは、第２の縦結合共振子型弾性波フィルタ部４０のＩＤＴ電極４２の第１のくし歯状電極４２ａに接続されている。ＩＤＴ電極３３の第１のくし歯状電極３３ａは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極３３の第２のくし歯状電極３３ｂは、第２の縦結合共振子型弾性波フィルタ部４０のＩＤＴ電極４３の第１のくし歯状電極４３ａに接続されている。 As shown in FIGS. 2 and 3, the first comb-shaped electrode 31 a of the IDT electrode 31 is connected to the unbalanced signal terminal 23. The second comb-like electrode 31b of the IDT electrode 31 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential. The first comb-like electrode 32a of the IDT electrode 32 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential. The second comb-shaped electrode 32 b of the IDT electrode 32 is connected to the first comb-shaped electrode 42 a of the IDT electrode 42 of the second longitudinally coupled resonator type acoustic wave filter unit 40. The first comb-like electrode 33a of the IDT electrode 33 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential. The second comb-like electrode 33 b of the IDT electrode 33 is connected to the first comb-like electrode 43 a of the IDT electrode 43 of the second longitudinally coupled resonator type acoustic wave filter unit 40.
　図２及び図３に示すように、ＩＤＴ電極４１の第１のくし歯状電極４１ａは、グラウンド電位に接続されている接地用電極パッド２９ａ（図３を参照）に接続されている。ＩＤＴ電極４１の第２のくし歯状電極４１ｂは、第１の平衡信号端子２４に接続されている。ＩＤＴ電極４２の第１のくし歯状電極４２ａは、第１の縦結合共振子型弾性波フィルタ部３０のＩＤＴ電極３２の第２のくし歯状電極３２ｂに接続されている。ＩＤＴ電極４２の第２のくし歯状電極４２ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極４３の第１のくし歯状電極４３ａは、第１の縦結合共振子型弾性波フィルタ部３０のＩＤＴ電極３３の第２のくし歯状電極３３ｂに接続されている。ＩＤＴ電極４３の第２のくし歯状電極４３ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。 2 and 3, the first comb-like electrode 41a of the IDT electrode 41 is connected to a ground electrode pad 29a (see FIG. 3) connected to the ground potential. The second comb-like electrode 41 b of the IDT electrode 41 is connected to the first balanced signal terminal 24. The first comb-shaped electrode 42 a of the IDT electrode 42 is connected to the second comb-shaped electrode 32 b of the IDT electrode 32 of the first longitudinally coupled resonator type acoustic wave filter unit 30. The second comb-like electrode 42b of the IDT electrode 42 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential. The first comb-shaped electrode 43 a of the IDT electrode 43 is connected to the second comb-shaped electrode 33 b of the IDT electrode 33 of the first longitudinally coupled resonator type acoustic wave filter unit 30. The second comb-like electrode 43b of the IDT electrode 43 is connected to a ground electrode pad 27 (see FIG. 3) connected to the ground potential.
　なお、本実施形態では、図１～図３に示すように、第１の縦結合共振子型弾性波フィルタ部３０と、不平衡信号端子２３との間には、弾性波共振子７０が接続されている。図２に示すように、弾性波共振子７０は、圧電基板２６上に形成されているＩＤＴ電極７０ａを備えている。ＩＤＴ電極７０ａは、第１及び第２のくし歯状電極７０ａ１，７０ａ２を備えている。第１のくし歯状電極７０ａ１は、不平衡信号端子２３に接続されている。一方、第２のくし歯状電極７０ａ２は、第１の縦結合共振子型弾性波フィルタ部３０のＩＤＴ電極３１の第１のくし歯状電極３１ａに接続されている。 In the present embodiment, as shown in FIGS. 1 to 3, an acoustic wave resonator 70 is connected between the first longitudinally coupled resonator type acoustic wave filter unit 30 and the unbalanced signal terminal 23. Has been. As shown in FIG. 2, the acoustic wave resonator 70 includes an IDT electrode 70 a formed on the piezoelectric substrate 26. The IDT electrode 70a includes first and second comb-like electrodes 70a1 and 70a2. The first comb-like electrode 70 a 1 is connected to the unbalanced signal terminal 23. On the other hand, the second comb-like electrode 70 a 2 is connected to the first comb-like electrode 31 a of the IDT electrode 31 of the first longitudinally coupled resonator type acoustic wave filter unit 30.
　図２及び図３に示すように、第３及び第４の縦結合共振子型弾性波フィルタ部５０，６０は、不平衡信号端子２３と、第２の平衡信号端子２５との間に接続されている。そして、第３の縦結合共振子型弾性波フィルタ部５０は、第４の縦結合共振子型弾性波フィルタ部６０と縦続接続されている。 As shown in FIGS. 2 and 3, the third and fourth longitudinally coupled resonator type acoustic wave filter units 50 and 60 are connected between the unbalanced signal terminal 23 and the second balanced signal terminal 25. ing. The third longitudinally coupled resonator type acoustic wave filter unit 50 is cascade-connected to the fourth longitudinally coupled resonator type acoustic wave filter unit 60.
　図２及び図３に示すように、第３の縦結合共振子型弾性波フィルタ部５０は、圧電基板２６上に、弾性波の伝搬方向に沿って形成されている３つのＩＤＴ電極５１～５３を備えている。圧電基板２６上において、ＩＤＴ電極５１～５３が形成されている領域の弾性波の伝搬方向の両側には、一対のグレーティング反射器５４，５５が形成されている。 As shown in FIGS. 2 and 3, the third longitudinally coupled resonator type acoustic wave filter unit 50 includes three IDT electrodes 51 to 53 formed on the piezoelectric substrate 26 along the propagation direction of the acoustic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 54 and 55 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 51 to 53 are formed.
　ＩＤＴ電極５１は、ＩＤＴ電極５１～５３のうち、弾性波の伝搬方向における中央に位置している。ＩＤＴ電極５１は、第１及び第２のくし歯状電極５１ａ，５１ｂを備えている。ＩＤＴ電極５２は、弾性波の伝搬方向において、ＩＤＴ電極５１に隣接して形成されている。ＩＤＴ電極５２は、第１及び第２のくし歯状電極５２ａ，５２ｂを備えている。ＩＤＴ電極５３は、弾性波の伝搬方向において、ＩＤＴ電極５１に隣接して形成されている。ＩＤＴ電極５３は、第１及び第２のくし歯状電極５３ａ，５３ｂを備えている。 The IDT electrode 51 is located in the center of the IDT electrodes 51 to 53 in the propagation direction of the elastic wave. The IDT electrode 51 includes first and second comb- like electrodes 51a and 51b. The IDT electrode 52 is formed adjacent to the IDT electrode 51 in the elastic wave propagation direction. The IDT electrode 52 includes first and second comb- like electrodes 52a and 52b. The IDT electrode 53 is formed adjacent to the IDT electrode 51 in the elastic wave propagation direction. The IDT electrode 53 includes first and second comb- like electrodes 53a and 53b.
　図２及び図３に示すように、第４の縦結合共振子型弾性波フィルタ部６０は、圧電基板２６上に、弾性波の伝搬方向に沿って形成されている３つのＩＤＴ電極６１～６３を備えている。圧電基板２６上において、ＩＤＴ電極６１～６３が形成されている領域の弾性波の伝搬方向の両側には、一対のグレーティング反射器６４，６５が形成されている。 As shown in FIGS. 2 and 3, the fourth longitudinally coupled resonator type elastic wave filter unit 60 includes three IDT electrodes 61 to 63 formed on the piezoelectric substrate 26 along the propagation direction of the elastic wave. It has. On the piezoelectric substrate 26, a pair of grating reflectors 64 and 65 are formed on both sides of the propagation direction of the elastic wave in the region where the IDT electrodes 61 to 63 are formed.
　ＩＤＴ電極６１は、ＩＤＴ電極６１～６３のうち、弾性波の伝搬方向における中央に位置している。ＩＤＴ電極６１は、第１及び第２のくし歯状電極６１ａ，６１ｂを備えている。ＩＤＴ電極６２は、弾性波の伝搬方向において、ＩＤＴ電極６１に隣接して形成されている。ＩＤＴ電極６２は、第１及び第２のくし歯状電極６２ａ，６２ｂを備えている。ＩＤＴ電極６３は、弾性波の伝搬方向において、ＩＤＴ電極６１に隣接して形成されている。ＩＤＴ電極６３は、第１及び第２のくし歯状電極６３ａ，６３ｂを備えている。 The IDT electrode 61 is located at the center of the IDT electrodes 61 to 63 in the elastic wave propagation direction. The IDT electrode 61 includes first and second comb- like electrodes 61a and 61b. The IDT electrode 62 is formed adjacent to the IDT electrode 61 in the propagation direction of the elastic wave. The IDT electrode 62 includes first and second comb- like electrodes 62a and 62b. The IDT electrode 63 is formed adjacent to the IDT electrode 61 in the propagation direction of the elastic wave. The IDT electrode 63 includes first and second comb- like electrodes 63a and 63b.
　図２及び図３に示すように、ＩＤＴ電極５１の第１のくし歯状電極５１ａは、不平衡信号端子２３に接続されている。ＩＤＴ電極５１の第２のくし歯状電極５１ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極５２の第１のくし歯状電極５２ａは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極５２の第２のくし歯状電極５２ｂは、第４の縦結合共振子型弾性波フィルタ部６０のＩＤＴ電極６２の第１のくし歯状電極６２ａに接続されている。ＩＤＴ電極５３の第１のくし歯状電極５３ａは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極５３の第２のくし歯状電極５３ｂは、第４の縦結合共振子型弾性波フィルタ部６０のＩＤＴ電極６３の第１のくし歯状電極６３ａに接続されている。 2 and 3, the first comb-like electrode 51 a of the IDT electrode 51 is connected to the unbalanced signal terminal 23. The second comb-like electrode 51b of the IDT electrode 51 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential. The first comb-like electrode 52a of the IDT electrode 52 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential. The second comb-like electrode 52 b of the IDT electrode 52 is connected to the first comb-like electrode 62 a of the IDT electrode 62 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60. The first comb-like electrode 53a of the IDT electrode 53 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential. The second comb-like electrode 53 b of the IDT electrode 53 is connected to the first comb-like electrode 63 a of the IDT electrode 63 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60.
　図２及び図３に示すように、ＩＤＴ電極６１の第１のくし歯状電極６１ａは、グラウンド電位に接続されている接地用電極パッド２９ｂ（図３を参照）に接続されている。ＩＤＴ電極６１の第２のくし歯状電極６１ｂは、第２の平衡信号端子２５に接続されている。ＩＤＴ電極６２の第１のくし歯状電極６２ａは、第３の縦結合共振子型弾性波フィルタ部５０のＩＤＴ電極５２の第２のくし歯状電極５２ｂに接続されている。ＩＤＴ電極６２の第２のくし歯状電極６２ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。ＩＤＴ電極６３の第１のくし歯状電極６３ａは、第３の縦結合共振子型弾性波フィルタ部５０のＩＤＴ電極５３の第２のくし歯状電極５３ｂに接続されている。ＩＤＴ電極６３の第２のくし歯状電極６３ｂは、グラウンド電位に接続されている接地用電極パッド２７（図３を参照）に接続されている。 As shown in FIGS. 2 and 3, the first comb-like electrode 61a of the IDT electrode 61 is connected to a ground electrode pad 29b (see FIG. 3) connected to the ground potential. The second comb-like electrode 61 b of the IDT electrode 61 is connected to the second balanced signal terminal 25. The first comb-like electrode 62 a of the IDT electrode 62 is connected to the second comb-like electrode 52 b of the IDT electrode 52 of the third longitudinally coupled resonator type acoustic wave filter unit 50. The second comb-like electrode 62b of the IDT electrode 62 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential. The first comb-like electrode 63 a of the IDT electrode 63 is connected to the second comb-like electrode 53 b of the IDT electrode 53 of the third longitudinally coupled resonator type acoustic wave filter unit 50. The second comb-like electrode 63b of the IDT electrode 63 is connected to the ground electrode pad 27 (see FIG. 3) connected to the ground potential.
　なお、本実施形態では、図１～図３に示すように、第３の縦結合共振子型弾性波フィルタ部５０と、不平衡信号端子２３との間には、弾性波共振子７１が接続されている。図２に示すように、弾性波共振子７１は、圧電基板２６上に形成されているＩＤＴ電極７１ａを備えている。ＩＤＴ電極７１ａは、第１及び第２のくし歯状電極７１ａ１，７１ａ２を備えている。第１のくし歯状電極７１ａ１は、不平衡信号端子２３に接続されている。一方、第２のくし歯状電極７１ａ２は、第３の縦結合共振子型弾性波フィルタ部５０のＩＤＴ電極５１の第１のくし歯状電極５１ａに接続されている。 In the present embodiment, as shown in FIGS. 1 to 3, an acoustic wave resonator 71 is connected between the third longitudinally coupled resonator type acoustic wave filter unit 50 and the unbalanced signal terminal 23. Has been. As shown in FIG. 2, the acoustic wave resonator 71 includes an IDT electrode 71 a formed on the piezoelectric substrate 26. The IDT electrode 71a includes first and second comb-like electrodes 71a1 and 71a2. The first comb-like electrode 71 a 1 is connected to the unbalanced signal terminal 23. On the other hand, the second comb-like electrode 71a2 is connected to the first comb-like electrode 51a of the IDT electrode 51 of the third longitudinally coupled resonator type acoustic wave filter unit 50.
　本実施形態では、ＩＤＴ電極４１と、ＩＤＴ電極６１とは、弾性波の伝搬方向に直行する方向を対称軸として、反転した構成とされている。従って、弾性波フィルタ部２８は、第１の平衡信号端子２４から出力される信号と、第２の平衡信号端子２５から出力される信号とが互いに逆相の関係となっている。 In this embodiment, the IDT electrode 41 and the IDT electrode 61 are configured to be reversed with the direction orthogonal to the propagation direction of the elastic wave as the axis of symmetry. Therefore, in the acoustic wave filter unit 28, the signal output from the first balanced signal terminal 24 and the signal output from the second balanced signal terminal 25 are in an opposite phase relationship.
　なお、図３に示すように、各電極を接続する配線が交差している交差部１４ａ～１４ｈにおいては、交差する配線間に絶縁膜１５が形成されている。この絶縁膜１５により、交差する配線間が絶縁されている。絶縁膜１５の材質は特に限定されない。絶縁膜１５は、例えば、ポリイミドなどの樹脂や、ＳｉＯ２やＳｉＮなどの無機誘電体により形成することができる。 As shown in FIG. 3, in the intersections 14a to 14h where the wirings connecting the electrodes intersect, an insulating film 15 is formed between the intersecting wirings. The insulating film 15 insulates the intersecting wires from each other. The material of the insulating film 15 is not particularly limited. The insulating film 15 can be formed of, for example, a resin such as polyimide or an inorganic dielectric such as SiO 2 or SiN.
　また、本実施形態におけるＩＤＴ電極や反射器等は、適宜の導電材料により形成することができる。例えば、ＩＤＴ電極や反射器等は、Ａｌ，Ｃｕ、Ｎｉ，Ａｕ，Ａｇ，Ｐｔ，Ａｕ，Ｃｒ等の金属や、それら金属を少なくとも一種以上含む合金などにより形成することができる。また、ＩＤＴ電極や反射器等は、例えば、複数の導電膜が積層された導電膜積層体により構成されていてもよい。 In addition, the IDT electrode, the reflector, and the like in the present embodiment can be formed of an appropriate conductive material. For example, the IDT electrode, the reflector, and the like can be formed of a metal such as Al, Cu, Ni, Au, Ag, Pt, Au, or Cr, or an alloy containing at least one of these metals. Moreover, the IDT electrode, the reflector, and the like may be configured by, for example, a conductive film stack in which a plurality of conductive films are stacked.
　以上説明したように、本実施形態では、第１の平衡信号端子２４に接続されているＩＤＴ電極４１の第１のくし歯状電極４１ａと、第２の平衡信号端子２５に接続されているＩＤＴ電極６１の第１のくし歯状電極６１ａとは、圧電基板上において、互いに異なる接地用電極パッド２９ａ，２９ｂに接続されている。このため、互いに逆相の関係にある、ＩＤＴ電極４１を流れる電流と、ＩＤＴ電極６１を流れる電流とが、圧電基板２６上で合わさることを効果的に抑制することができる。その結果、下記の実例においても裏付けられるように、第１及び第２の平衡信号端子２４，２５間の平衡度の悪化を効果的に抑制することができる。また、第１及び第２の平衡信号端子２４，２５間の平衡度の悪化を抑制できるため、差動減衰量、差動アイソレーションの悪化も抑制することができる。 As described above, in the present embodiment, the IDT electrode 41a of the IDT electrode 41 connected to the first balanced signal terminal 24 and the IDT connected to the second balanced signal terminal 25 are used. The first comb-like electrode 61a of the electrode 61 is connected to different grounding electrode pads 29a and 29b on the piezoelectric substrate. For this reason, it is possible to effectively suppress the current flowing through the IDT electrode 41 and the current flowing through the IDT electrode 61, which are in an opposite phase relationship, from being combined on the piezoelectric substrate 26. As a result, it is possible to effectively suppress the deterioration of the balance between the first and second balanced signal terminals 24 and 25, as supported by the following examples. Moreover, since the deterioration of the balance degree between the 1st and 2nd balanced signal terminals 24 and 25 can be suppressed, the deterioration of differential attenuation amount and differential isolation can also be suppressed.
　それに対して、例えば、第１の平衡信号端子に接続されているＩＤＴ電極のくし歯状電極と、第２の平衡信号端子に接続されているＩＤＴ電極のくし歯状電極とが同じ接地用電極パッドに接続されている場合は、その接地用電極パッド及び、接地用電極パッドに接続されている配線に、互いに逆相の関係にある２つの電流が流れることになる。その結果、第１及び第２の平衡信号端子間の平衡度が悪化し、それに伴い、差動減衰量、差動アイソレーションも悪化してしまう。 On the other hand, for example, the comb electrode of the IDT electrode connected to the first balanced signal terminal and the comb electrode of the IDT electrode connected to the second balanced signal terminal are the same ground electrode. When connected to the pad, two currents having opposite phases flow through the grounding electrode pad and the wiring connected to the grounding electrode pad. As a result, the balance between the first and second balanced signal terminals is deteriorated, and accordingly, the differential attenuation amount and the differential isolation are also deteriorated.
　以下、このことについて実例を挙げて説明する。 Hereafter, this will be explained with examples.
　本実施形態のデュプレクサ１の比較例として、受信側フィルタ２０に替えて、図４に示す受信側フィルタ３００を有すること以外は、上記本実施形態のデュプレクサ１と同様の構成を有するデュプレクサを作製した。そして、上記本実施形態のデュプレクサ１と、比較例に係るデュプレクサとのそれぞれにおいて、不平衡信号端子２３と、第１及び第２の平衡信号端子２４，２５のそれぞれとの間の減衰量特性等を測定した。 As a comparative example of the duplexer 1 of the present embodiment, a duplexer having the same configuration as the duplexer 1 of the present embodiment except that the receiver filter 300 shown in FIG. . In each of the duplexer 1 of the present embodiment and the duplexer according to the comparative example, the attenuation characteristic between the unbalanced signal terminal 23 and each of the first and second balanced signal terminals 24 and 25, etc. Was measured.
　なお、図４に示す受信側フィルタ３００は、下記の（１）～（２）を除いては、上記実施形態の受信側フィルタ２０と同様の構成を有している。 Note that the reception-side filter 300 shown in FIG. 4 has the same configuration as the reception-side filter 20 of the above-described embodiment except for the following (1) to (2).
　（１）ＩＤＴ電極４１の第１のくし歯状電極４１ａと、ＩＤＴ電極６１の第１のくし歯状電極６１ａとが、共通に、接地用電極パッド２７に接続されていること (1) The first comb-shaped electrode 41a of the IDT electrode 41 and the first comb-shaped electrode 61a of the IDT electrode 61 are connected to the ground electrode pad 27 in common.
　（２）ＩＤＴ電極３１の第２のくし歯状電極３１ｂが接地用電極パッド２９ａに接続されており、ＩＤＴ電極５１の第２のくし歯状電極５１ｂが接地用電極パッド２９ｂに接続されていること (2) The second comb-like electrode 31b of the IDT electrode 31 is connected to the ground electrode pad 29a, and the second comb-like electrode 51b of the IDT electrode 51 is connected to the ground electrode pad 29b. thing
　また、図４に示す比較例では、説明の便宜上、上記本実施形態と実質的に同様の機能を有する部材を同じ符号で参照している。 In the comparative example shown in FIG. 4, members having substantially the same functions as those of the above-described embodiment are referred to by the same reference numerals for convenience of explanation.
　図５は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、アンテナ端子１０と第１の受信側信号端子２１との間の減衰量特性を表すグラフである。図６は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、アンテナ端子１０と第２の受信側信号端子２２との間の減衰量特性を表すグラフである。図７は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、アンテナ端子１０と第１及び第２の受信側信号端子２１，２２との間の差動減衰量特性を表すグラフである。図８は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、送信側信号端子１２と第１の受信側信号端子２１との間のアイソレーション特性を表すグラフである。図９は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、送信側信号端子１２と第２の受信側信号端子２２との間のアイソレーション特性を表すグラフである。図１０は、本実施形態のデュプレクサ１と比較例のデュプレクサとにおける、送信側信号端子１２と第１及び第２の受信側信号端子２１，２２との間の差動アイソレーション特性を表すグラフである。図５～図１０のそれぞれにおいて、実線が本実施形態を示し、一点破線が比較例を示している。 FIG. 5 is a graph showing the attenuation characteristic between the antenna terminal 10 and the first reception-side signal terminal 21 in the duplexer 1 of the present embodiment and the duplexer of the comparative example. FIG. 6 is a graph showing the attenuation characteristic between the antenna terminal 10 and the second reception-side signal terminal 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example. FIG. 7 is a graph showing the differential attenuation characteristics between the antenna terminal 10 and the first and second receiving signal terminals 21 and 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example. FIG. 8 is a graph showing isolation characteristics between the transmission-side signal terminal 12 and the first reception-side signal terminal 21 in the duplexer 1 of the present embodiment and the duplexer of the comparative example. FIG. 9 is a graph showing the isolation characteristics between the transmission-side signal terminal 12 and the second reception-side signal terminal 22 in the duplexer 1 of the present embodiment and the duplexer of the comparative example. FIG. 10 is a graph showing differential isolation characteristics between the transmission-side signal terminal 12 and the first and second reception- side signal terminals 21 and 22 in the duplexer 1 of this embodiment and the duplexer of the comparative example. is there. In each of FIGS. 5 to 10, a solid line indicates the present embodiment, and a dashed line indicates a comparative example.
　なお、上記した差動減衰量と差動アイソレーションはＳパラメータを用いて以下のように定義される。
Ｓｄｄ１＝（Ｓ３１－Ｓ４１）／｛（２）１／２｝
Ｓｄｄ２＝（Ｓ３２－Ｓ４２）／｛（２）１／２｝
　但し、
　Ｓｄｄ１：差動減衰量、
　Ｓｄｄ２：差動アイソレーション、
　Ｓ３１：アンテナ端子１０から第１の受信側信号端子２１へのＳパラメータ、
　Ｓ４１：アンテナ端子１０から第２の受信側信号端子２２へのＳパラメータ、
　Ｓ３２：送信側信号端子１２から第１の受信側信号端子２１へのＳパラメータ、
　Ｓ４２：送信側信号端子１２から第２の受信側信号端子２２へのＳパラメータ、
である。 The above-described differential attenuation and differential isolation are defined as follows using the S parameter.
Sdd1 = (S31-S41) / {(2) 1/2}
Sdd2 = (S32-S42) / {(2) 1/2}
However,
Sdd1: differential attenuation,
Sdd2: differential isolation,
S31: S parameter from the antenna terminal 10 to the first receiving signal terminal 21;
S41: S parameter from the antenna terminal 10 to the second receiving signal terminal 22;
S32: S parameter from the transmission side signal terminal 12 to the first reception side signal terminal 21,
S42: S parameter from the transmission side signal terminal 12 to the second reception side signal terminal 22,
It is.
　図５及び図６に示す結果から明らかなように、比較例のデュプレクサでは、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、アンテナ端子１０と第１の受信側信号端子２１との間の減衰量特性と、アンテナ端子１０と第２の受信側信号端子２２との間の減衰量特性とが大きく異なっている。それに対して、本実施形態のデュプレクサ１では、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、アンテナ端子１０と第１の受信側信号端子２１との間の減衰量特性と、アンテナ端子１０と第２の受信側信号端子２２との間の減衰量特性とが比較的近似している。 As is apparent from the results shown in FIGS. 5 and 6, in the duplexer of the comparative example, in the pass band (824 MHz to 849 MHz) of the transmission side filter 13, the antenna terminal 10 and the first reception side signal terminal 21 are not connected. The attenuation characteristic and the attenuation characteristic between the antenna terminal 10 and the second receiving signal terminal 22 are greatly different. On the other hand, in the duplexer 1 of the present embodiment, the attenuation characteristic between the antenna terminal 10 and the first reception side signal terminal 21 in the pass band (824 MHz to 849 MHz) of the transmission side filter 13, and the antenna terminal 10 And the second receiving side signal terminal 22 are relatively approximate to each other.
　また、図７に示す結果から明らかなように、本実施形態のデュプレクサ１では、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、比較例のデュプレクサよりも差動減衰量が大きい。 As is apparent from the results shown in FIG. 7, the duplexer 1 of the present embodiment has a larger differential attenuation in the pass band (824 MHz to 849 MHz) of the transmission-side filter 13 than the duplexer of the comparative example.
　さらに、図８及び図９に示す結果から明らかなように、比較例のデュプレクサでは、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、送信側信号端子１２と第１の受信側信号端子２１との間のアイソレーション特性と、送信側信号端子１２と第２の受信側信号端子２２との間のアイソレーション特性とが大きく異なっている。それに対して、本実施形態のデュプレクサ１では、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、送信側信号端子１２と第１の受信側信号端子２１との間のアイソレーション特性と、送信側信号端子１２と第２の受信側信号端子２２との間のアイソレーション特性とが比較的近似している。 Further, as is apparent from the results shown in FIGS. 8 and 9, in the duplexer of the comparative example, in the pass band (824 MHz to 849 MHz) of the transmission filter 13, the transmission signal terminal 12 and the first reception signal terminal 21 are used. And the isolation characteristic between the transmission side signal terminal 12 and the second reception side signal terminal 22 are greatly different. On the other hand, in the duplexer 1 of the present embodiment, the isolation characteristics between the transmission side signal terminal 12 and the first reception side signal terminal 21 in the pass band (824 MHz to 849 MHz) of the transmission side filter 13 and the transmission The isolation characteristic between the side signal terminal 12 and the second reception side signal terminal 22 is relatively approximate.
　また、図１０に示す結果から明らかなように、本実施形態のデュプレクサ１では、送信側フィルタ１３の通過帯域（８２４ＭＨｚ～８４９ＭＨｚ）において、比較例のデュプレクサよりも差動アイソレーションが大きい。 As is clear from the results shown in FIG. 10, the duplexer 1 of the present embodiment has a larger differential isolation in the pass band (824 MHz to 849 MHz) of the transmission-side filter 13 than the duplexer of the comparative example.
　以上の結果より、第１の平衡信号端子２４に接続されているＩＤＴ電極４１の第１のくし歯状電極４１ａと、第２の平衡信号端子２５に接続されているＩＤＴ電極６１の第１のくし歯状電極６１ａとを互いに異なる接地用電極パッド２９ａ，２９ｂに接続することにより、差動減衰量、差動アイソレーションを大きくできること、第１及び第２の平衡信号端子２４，２５間の平衡度の悪化を抑制できることが分かる。 From the above results, the first comb-shaped electrode 41a of the IDT electrode 41 connected to the first balanced signal terminal 24 and the first of the IDT electrode 61 connected to the second balanced signal terminal 25 are shown. By connecting the comb-like electrode 61a to different grounding electrode pads 29a and 29b, the differential attenuation and the differential isolation can be increased, and the balance between the first and second balanced signal terminals 24 and 25 can be increased. It can be seen that the deterioration of the degree can be suppressed.
　また、本実施形態では、図３に示すように、グラウンド電位に接続されている全てのくし歯状電極のうち、ＩＤＴ電極４１の第１のくし歯状電極４１ａとＩＤＴ電極６１の第１のくし歯状電極６１ａとを除いたくし歯状電極３１ｂ，３２ａ，３３ａ，４２ｂ，４３ｂ，５１ｂ，５２ａ，５３ａ，６２ｂ，６３ｂは、圧電基板２６上に形成された接地用電極パッド２７に共通に接続されている。このため、フィルタ全体としてアースを大きくすることができる。このため、帯域外減衰量の劣化を抑制することができる。但し、本発明は、この構成に限定されない。例えば、くし歯状電極３１ｂ，３２ａ，３３ａ，４２ｂ，４３ｂ，５１ｂ，５２ａ，５３ａ，６２ｂ，６３ｂは、複数の接地用電極パッドに接続されていてもよい。 In the present embodiment, as shown in FIG. 3, the first comb-shaped electrode 41 a of the IDT electrode 41 and the first of the IDT electrode 61 among all the comb-shaped electrodes connected to the ground potential are used. The comb- like electrodes 31b, 32a, 33a, 42b, 43b, 51b, 52a, 53a, 62b, and 63b, excluding the comb-like electrode 61a, are commonly connected to the ground electrode pad 27 formed on the piezoelectric substrate 26. Has been. For this reason, grounding can be enlarged as a whole filter. For this reason, deterioration of the out-of-band attenuation can be suppressed. However, the present invention is not limited to this configuration. For example, the comb- like electrodes 31b, 32a, 33a, 42b, 43b, 51b, 52a, 53a, 62b, and 63b may be connected to a plurality of ground electrode pads.
　なお、接地用電極パッド２９ａ，２９ｂのそれぞれは、圧電基板２６が実装される実装基板上に形成されているランド及び配線に接続されることとなる。ここで、接地用電極パッド２９ａが接続されるランド及び配線と、接地用電極パッド２９ｂが接続されるランド及び配線とは、実装基板で互いに接続されていてもよく、互いに接続されていなくてもよい。すなわち、本発明においては、第１の平衡信号端子に接続されているＩＤＴ電極を構成する２つのくし歯状電極のうちのグラウンド電位に接続されるくし歯状電極が接続されている圧電基板上の接地用電極パッドと、第２の平衡信号端子に接続されているＩＤＴ電極を構成する２つのくし歯状電極のうちのグラウンド電位に接続されるくし歯状電極が接続されている圧電基板上の接地用電極パッドとが異なっている限りにおいて、実装基板上の回路構成は特に限定されない。これは、互いに逆相の関係にある電流が圧電基板上において合わさることにより第１及び第２の平衡信号端子間の平衡度が低下するのであって、互いに逆相の関係にある電流が圧電基板上において合わさらない限り第１及び第２の平衡信号端子間の平衡度が低下し難いためである。 Each of the ground electrode pads 29a and 29b is connected to lands and wirings formed on a mounting substrate on which the piezoelectric substrate 26 is mounted. Here, the land and wiring to which the grounding electrode pad 29a is connected and the land and wiring to which the grounding electrode pad 29b is connected may be connected to each other on the mounting board or may not be connected to each other. Good. That is, in the present invention, on the piezoelectric substrate to which the comb-like electrode connected to the ground potential of the two comb-like electrodes constituting the IDT electrode connected to the first balanced signal terminal is connected. On the piezoelectric substrate to which the comb-like electrode connected to the ground potential of the two comb-like electrodes constituting the IDT electrode connected to the second balanced signal terminal is connected. As long as the grounding electrode pad is different, the circuit configuration on the mounting substrate is not particularly limited. This is because the balance between the first and second balanced signal terminals is reduced when currents in opposite phases are combined on the piezoelectric substrate, and the currents in opposite phases are reduced. This is because the balance between the first and second balanced signal terminals is unlikely to decrease unless they are combined together.
　以下、上記実施形態の変形例について説明する。下記の変形例の説明において、上記実施形態と実質的に共通の機能を有する部材を共通の符号で参照し、説明を省略する。 Hereinafter, modifications of the above embodiment will be described. In the following description of the modified example, members having substantially the same functions as those of the above-described embodiment are referred to by common reference numerals, and description thereof is omitted.
　（第１～第３の変形例）
　図１１は、第１の変形例に係る受信側フィルタの模式的構成図である。図１２は、第２の変形例に係る受信側フィルタの模式的構成図である。図１３は、第３の変形例に係る受信側フィルタの模式的構成図である。 (First to third modifications)
FIG. 11 is a schematic configuration diagram of a reception-side filter according to the first modification. FIG. 12 is a schematic configuration diagram of a reception-side filter according to the second modification. FIG. 13 is a schematic configuration diagram of a reception-side filter according to a third modification.
　上記第１の実施形態では、弾性波フィルタ部２８が第１～第４の縦結合共振子型弾性波フィルタ部３０，４０，５０，６０を含んでいる例について説明した。第１の実施形態では、第１の縦結合共振子型弾性波フィルタ部３０と第２の縦結合共振子型弾性波フィルタ部４０とが縦続接続されている。また、第３の縦結合共振子型弾性波フィルタ部５０と第４の縦結合共振子型弾性波フィルタ部６０とが縦続接続されている。但し、本発明は、この構成に限定されない。 In the first embodiment, the example in which the elastic wave filter unit 28 includes the first to fourth longitudinally coupled resonator type elastic wave filter units 30, 40, 50, 60 has been described. In the first embodiment, the first longitudinally coupled resonator type acoustic wave filter unit 30 and the second longitudinally coupled resonator type acoustic wave filter unit 40 are cascade-connected. Further, the third longitudinally coupled resonator type acoustic wave filter unit 50 and the fourth longitudinally coupled resonator type acoustic wave filter unit 60 are connected in cascade. However, the present invention is not limited to this configuration.
　例えば、図１１に示すように、弾性波フィルタ部２８を第２及び第４の縦結合共振子型弾性波フィルタ部４０，６０により構成してもよい。 For example, as shown in FIG. 11, the elastic wave filter unit 28 may be constituted by second and fourth longitudinally coupled resonator type elastic wave filter units 40 and 60.
　また、例えば図１２に示すように、弾性波フィルタ部２８を、ひとつの縦結合共振子型弾性波フィルタ部により構成してもよい。この図１２に示す第２の変形例では、弾性波フィルタ部２８を構成する縦結合共振子型弾性波フィルタ部は、５つのＩＤＴ電極を有する、所謂５ＩＤＴ型の縦結合共振子型弾性波フィルタ部により構成されている。 Further, for example, as shown in FIG. 12, the elastic wave filter unit 28 may be constituted by one longitudinally coupled resonator type elastic wave filter unit. In the second modification shown in FIG. 12, the so-called 5IDT type longitudinally coupled resonator type acoustic wave filter in which the longitudinally coupled resonator type acoustic wave filter unit constituting the acoustic wave filter unit 28 has five IDT electrodes. It consists of parts.
　具体的には、図１２に示すように、第２の変形例では、弾性波フィルタ部２８は、圧電基板２６上に、弾性波の伝搬方向に沿って形成されている５つのＩＤＴ電極８１～８５を備えている。圧電基板２６上において、ＩＤＴ電極８１～８５が形成されている領域の弾性波の伝搬方向の両側には、一対のグレーティング反射器８６，８７が形成されている。 Specifically, as shown in FIG. 12, in the second modification example, the acoustic wave filter unit 28 includes five IDT electrodes 81 to 81 formed on the piezoelectric substrate 26 along the propagation direction of the acoustic wave. 85. On the piezoelectric substrate 26, a pair of grating reflectors 86 and 87 are formed on both sides of the elastic wave propagation direction in the region where the IDT electrodes 81 to 85 are formed.
　ＩＤＴ電極８１は、ＩＤＴ電極８１～８５のうち、弾性波の伝搬方向における中央に位置している。ＩＤＴ電極８１は、第１及び第２のくし歯状電極８１ａ，８１ｂを備えている。ＩＤＴ電極８２は、弾性波の伝搬方向において、ＩＤＴ電極８１に隣接して形成されている。ＩＤＴ電極８２は、第１及び第２のくし歯状電極８２ａ，８２ｂを備えている。ＩＤＴ電極８３は、弾性波の伝搬方向において、ＩＤＴ電極８１に隣接して形成されている。ＩＤＴ電極８３は、第１及び第２のくし歯状電極８３ａ，８３ｂを備えている。ＩＤＴ電極８４は、弾性波の伝搬方向において、ＩＤＴ電極８２に隣接して形成されている。ＩＤＴ電極８４は、第１及び第２のくし歯状電極８４ａ，８４ｂを備えている。ＩＤＴ電極８５は、弾性波の伝搬方向において、ＩＤＴ電極８３に隣接して形成されている。ＩＤＴ電極８５は、第１及び第２のくし歯状電極８５ａ，８５ｂを備えている。 The IDT electrode 81 is located in the center of the IDT electrodes 81 to 85 in the elastic wave propagation direction. The IDT electrode 81 includes first and second comb- like electrodes 81a and 81b. The IDT electrode 82 is formed adjacent to the IDT electrode 81 in the propagation direction of the elastic wave. The IDT electrode 82 includes first and second comb- like electrodes 82a and 82b. The IDT electrode 83 is formed adjacent to the IDT electrode 81 in the elastic wave propagation direction. The IDT electrode 83 includes first and second comb- like electrodes 83a and 83b. The IDT electrode 84 is formed adjacent to the IDT electrode 82 in the propagation direction of the elastic wave. The IDT electrode 84 includes first and second comb- like electrodes 84a and 84b. The IDT electrode 85 is formed adjacent to the IDT electrode 83 in the elastic wave propagation direction. The IDT electrode 85 includes first and second comb- like electrodes 85a and 85b.
　図１２に示すように、ＩＤＴ電極８１の第１のくし歯状電極８１ａは、不平衡信号端子２３に接続されている。ＩＤＴ電極８１の第２のくし歯状電極８１ｂは、グラウンド電位に接続されている接地用電極パッド２７に接続されている。ＩＤＴ電極８２の第１のくし歯状電極８２ａは、グラウンド電位に接続されている接地用電極パッド２９ｂに接続されている。ＩＤＴ電極８２の第２のくし歯状電極８２ｂは、第２の平衡信号端子２５に接続されている。ＩＤＴ電極８３の第１のくし歯状電極８３ａは、グラウンド電位に接続されている接地用電極パッド２９ａに接続されている。ＩＤＴ電極８３の第２のくし歯状電極８３ｂは、第１の平衡信号端子２４に接続されている。ＩＤＴ電極８４の第１のくし歯状電極８４ａは、不平衡信号端子２３に接続されている。ＩＤＴ電極８４の第２のくし歯状電極８４ｂは、グラウンド電位に接続されている接地用電極パッド２７に接続されている。ＩＤＴ電極８５の第１のくし歯状電極８５ａは、不平衡信号端子２３に接続されている。ＩＤＴ電極８５の第２のくし歯状電極８５ｂは、グラウンド電位に接続されている接地用電極パッド２７に接続されている。 As shown in FIG. 12, the first comb-shaped electrode 81 a of the IDT electrode 81 is connected to the unbalanced signal terminal 23. The second comb-like electrode 81b of the IDT electrode 81 is connected to the ground electrode pad 27 connected to the ground potential. The first comb-like electrode 82a of the IDT electrode 82 is connected to the ground electrode pad 29b connected to the ground potential. The second comb-like electrode 82 b of the IDT electrode 82 is connected to the second balanced signal terminal 25. The first comb-like electrode 83a of the IDT electrode 83 is connected to the ground electrode pad 29a connected to the ground potential. The second comb-like electrode 83 b of the IDT electrode 83 is connected to the first balanced signal terminal 24. The first comb-like electrode 84 a of the IDT electrode 84 is connected to the unbalanced signal terminal 23. The second comb-like electrode 84b of the IDT electrode 84 is connected to the ground electrode pad 27 connected to the ground potential. The first comb-like electrode 85 a of the IDT electrode 85 is connected to the unbalanced signal terminal 23. The second comb-like electrode 85b of the IDT electrode 85 is connected to the ground electrode pad 27 connected to the ground potential.
　第２の変形例では、ＩＤＴ電極８２と、ＩＤＴ電極８３とは、弾性波の伝搬方向に直行する方向を対称軸として、反転した構成とされている。従って、弾性波フィルタ部２８は、第１の平衡信号端子２４から出力される信号と、第２の平衡信号端子２５から出力される信号とが互いに逆相の関係となっている。 In the second modification, the IDT electrode 82 and the IDT electrode 83 are reversed with the direction orthogonal to the propagation direction of the acoustic wave as the axis of symmetry. Therefore, in the acoustic wave filter unit 28, the signal output from the first balanced signal terminal 24 and the signal output from the second balanced signal terminal 25 are in an opposite phase relationship.
　なお、本変形例におけるＩＤＴ電極８１～８５及びグレーティング反射器８６，８７の構成は、上記実施形態のＩＤＴ電極及び反射器の構成と実質的に等しい。 Note that the configurations of the IDT electrodes 81 to 85 and the grating reflectors 86 and 87 in this modification are substantially the same as the configurations of the IDT electrodes and the reflectors of the above embodiment.
　なお、図１２に示す第２の変形例では、弾性波フィルタ部２８を構成する縦結合共振子型弾性波フィルタ部が、５つのＩＤＴ電極を有する、所謂５ＩＤＴ型の縦結合共振子型弾性波フィルタ部である例について説明した。但し、本発明はこの構成に限定されない。 In the second modification shown in FIG. 12, the so-called 5IDT type longitudinally coupled resonator type acoustic wave in which the longitudinally coupled resonator type acoustic wave filter unit constituting the acoustic wave filter unit 28 has five IDT electrodes. The example which is a filter part was demonstrated. However, the present invention is not limited to this configuration.
　例えば、図１３に示すように、弾性波フィルタ部２８を構成する縦結合共振子型弾性波フィルタ部は、３つのＩＤＴ電極８１～８３を有する、所謂３ＩＤＴ型の縦結合共振子型弾性波フィルタ部であってもよい。 For example, as shown in FIG. 13, the longitudinally coupled resonator type acoustic wave filter portion constituting the acoustic wave filter unit 28 is a so-called 3IDT type longitudinally coupled resonator type acoustic wave filter having three IDT electrodes 81 to 83. Part.
　（第４の変形例）
　図１４は、第４の変形例に係る受信側フィルタの模式的構成図である。 (Fourth modification)
FIG. 14 is a schematic configuration diagram of a reception-side filter according to a fourth modification.
　上記実施形態では、第２の縦結合共振子型弾性波フィルタ部４０のＩＤＴ電極４１の第２のくし歯状電極４１ｂが第１の平衡信号端子２４に接続されており、ＩＤＴ電極４２，４３の第１のくし歯状電極４２ａ，４３ａが第１の縦結合共振子型弾性波フィルタ部３０と弾性波共振子７０とを介して不平衡信号端子２３に接続されていると共に、第４の縦結合共振子型弾性波フィルタ部６０のＩＤＴ電極６１の第２のくし歯状電極６１ｂが第２の平衡信号端子２５に接続されており、ＩＤＴ電極６２，６３の第１のくし歯状電極６２ａ，６３ａが第３の縦結合共振子型弾性波フィルタ部５０と弾性波共振子７１とを介して不平衡信号端子２３に接続されている例について説明した。但し、本発明は、この構成に限定されない。 In the above embodiment, the second comb-like electrode 41b of the IDT electrode 41 of the second longitudinally coupled resonator type acoustic wave filter unit 40 is connected to the first balanced signal terminal 24, and the IDT electrodes 42, 43 are connected. The first comb- like electrodes 42a and 43a are connected to the unbalanced signal terminal 23 via the first longitudinally coupled resonator type acoustic wave filter unit 30 and the acoustic wave resonator 70, and the fourth The second comb-like electrode 61b of the IDT electrode 61 of the longitudinally coupled resonator type acoustic wave filter unit 60 is connected to the second balanced signal terminal 25, and the first comb-like electrodes of the IDT electrodes 62 and 63 are connected. The example in which 62a and 63a are connected to the unbalanced signal terminal 23 via the third longitudinally coupled resonator type acoustic wave filter unit 50 and the acoustic wave resonator 71 has been described. However, the present invention is not limited to this configuration.
　例えば、図１４に示すように、第２の縦結合共振子型弾性波フィルタ部４０のＩＤＴ電極４１の第１のくし歯状電極４１ａが不平衡信号端子２３に接続されており、ＩＤＴ電極４２，４３の第２のくし歯状電極４２ｂ，４３ｂが第１の平衡信号端子２４に接続されていると共に、第４の縦結合共振子型弾性波フィルタ部６０のＩＤＴ電極６１の第１のくし歯状電極６１ａが不平衡信号端子２３に接続されており、ＩＤＴ電極６２，６３の第２のくし歯状電極６２ｂ，６３ｂが第２の平衡信号端子２５に接続されていてもよい。この場合は、第１の平衡信号端子２４に接続されているＩＤＴ電極４２，４３の第１のくし歯状電極４２ａ，４３ａと、第２の平衡信号端子２５に接続されているＩＤＴ電極６２，６３の第１のくし歯状電極６２ａ，６３ａとが互いに異なる接地用電極パッドに接続される。具体的には、本変形例では、第１の平衡信号端子２４に接続されているＩＤＴ電極４２，４３の第１のくし歯状電極４２ａ，４３ａは、接地用電極パッド２９ａに接続されている。第２の平衡信号端子２５に接続されているＩＤＴ電極６２，６３の第１のくし歯状電極６２ａ，６３ａは、接地用電極パッド２９ｂに接続されている。 For example, as shown in FIG. 14, the first comb-like electrode 41 a of the IDT electrode 41 of the second longitudinally coupled resonator type acoustic wave filter unit 40 is connected to the unbalanced signal terminal 23, and the IDT electrode 42. , 43 are connected to the first balanced signal terminal 24, and the first comb of the IDT electrode 61 of the fourth longitudinally coupled resonator type acoustic wave filter unit 60 is connected to the first balanced signal terminal 24. The tooth-shaped electrode 61 a may be connected to the unbalanced signal terminal 23, and the second comb-shaped electrodes 62 b and 63 b of the IDT electrodes 62 and 63 may be connected to the second balanced signal terminal 25. In this case, the first comb- like electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24, and the IDT electrodes 62 and 43 connected to the second balanced signal terminal 25, 63 first comb- like electrodes 62a and 63a are connected to different grounding electrode pads. Specifically, in this modification, the first comb- like electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24 are connected to the ground electrode pad 29a. . The first comb- like electrodes 62a and 63a of the IDT electrodes 62 and 63 connected to the second balanced signal terminal 25 are connected to the ground electrode pad 29b.
　なお、第１の平衡信号端子２４に接続されているＩＤＴ電極４２，４３の第１のくし歯状電極４２ａ，４３ａを互いに異なる接地用電極パッドに接続してもよい。同様に、第２の平衡信号端子２５に接続されているＩＤＴ電極６２，６３の第１のくし歯状電極６２ａ，６３ａを互いに異なる接地用電極パッドに接続してもよい。 Note that the first comb-shaped electrodes 42a and 43a of the IDT electrodes 42 and 43 connected to the first balanced signal terminal 24 may be connected to different grounding electrode pads. Similarly, the first comb- like electrodes 62a and 63a of the IDT electrodes 62 and 63 connected to the second balanced signal terminal 25 may be connected to different grounding electrode pads.
　（第５及び第６の変形例）
　図１５は、第５の変形例に係る受信側フィルタの一部分を拡大した略図的断面図である。図１６は、第６の変形例に係る受信側フィルタの一部分を拡大した略図的断面図である。 (Fifth and sixth modifications)
FIG. 15 is a schematic cross-sectional view in which a part of the reception-side filter according to the fifth modification is enlarged. FIG. 16 is a schematic cross-sectional view in which a part of the reception-side filter according to the sixth modification is enlarged.
　上記実施形態では、デュプレクサが弾性表面波を利用したものである例について説明した。但し、本発明はこの構成に限定されない。本発明に係る分波器や弾性波フィルタは、弾性境界波を利用したものであってもよい。 In the above embodiment, the example in which the duplexer uses surface acoustic waves has been described. However, the present invention is not limited to this configuration. The duplexer and the elastic wave filter according to the present invention may use boundary acoustic waves.
　例えば、図１５に示す第５の変形例では、受信側フィルタは、所謂２媒質型の弾性境界波フィルタ９０により構成されている。弾性境界波フィルタ９０は、第１の媒質層としての圧電基板２６と、圧電基板２６の上に積層されている、第２の媒質層としての誘電体層９１とを有する。圧電基板２６と誘電体層９１との間の境界には、電極９２が形成されている。この電極９２により各ＩＤＴ電極、反射器等が構成されている。 For example, in the fifth modification shown in FIG. 15, the reception-side filter is configured by a so-called two-medium type boundary acoustic wave filter 90. The boundary acoustic wave filter 90 includes a piezoelectric substrate 26 as a first medium layer and a dielectric layer 91 as a second medium layer stacked on the piezoelectric substrate 26. An electrode 92 is formed at the boundary between the piezoelectric substrate 26 and the dielectric layer 91. Each electrode 92 constitutes each IDT electrode, reflector, and the like.
　また、例えば、図１６に示す第６の変形例では、受信側フィルタは、所謂３媒質型の弾性境界波フィルタ９３により構成されている。弾性境界波フィルタ９３は、第１の媒質層としての圧電基板２６と、圧電基板２６の上に形成されている、第２の媒質層としての誘電体層９４と、圧電基板２６と誘電体層９４との間に形成されている、第３の媒質層としての誘電体層９５とを有する。圧電基板２６と誘電体層９５との間の境界には、電極９２が形成されている。この電極９２により各ＩＤＴ電極、反射器等が構成されている。誘電体層９５は、圧電基板２６及び誘電体層９４よりも横波音速が遅い材料により形成されている。このため、電極９２により構成されるＩＤＴ電極で発生した弾性境界波は、誘電体層９５内に効果的に閉じ込められる。 Further, for example, in the sixth modification shown in FIG. 16, the reception-side filter is constituted by a so-called three-medium boundary acoustic wave filter 93. The boundary acoustic wave filter 93 includes a piezoelectric substrate 26 as a first medium layer, a dielectric layer 94 as a second medium layer formed on the piezoelectric substrate 26, and the piezoelectric substrate 26 and the dielectric layer. 94, and a dielectric layer 95 serving as a third medium layer. An electrode 92 is formed at the boundary between the piezoelectric substrate 26 and the dielectric layer 95. Each electrode 92 constitutes each IDT electrode, reflector, and the like. The dielectric layer 95 is made of a material having a slower transverse sound speed than the piezoelectric substrate 26 and the dielectric layer 94. For this reason, the boundary acoustic wave generated by the IDT electrode constituted by the electrode 92 is effectively confined in the dielectric layer 95.
　本変形例においては、圧電基板２６は、例えば、ＹカットＸ伝搬、オイラー角で（０°，１０５°，０°）のＬｉＮｂＯ３基板により構成することができる。誘電体層９４は、例えば、ＳｉＮ層により構成することができる。誘電体層９１，９５は、例えば、ＳｉＯ２層により構成することができる。ＩＤＴ電極は、Ａｌよりも密度が大きい金属であるＣｕ、Ａｇ及びＡｕのうちの少なくとも一種の金属またはそれらの金属のうちの一種以上を含む合金により形成されていることが好ましい。 In the present modification, the piezoelectric substrate 26 can be configured by, for example, a LiNbO 3 substrate having Y cut X propagation and Euler angles (0 °, 105 °, 0 °). The dielectric layer 94 can be composed of, for example, a SiN layer. The dielectric layers 91 and 95 can be composed of, for example, a SiO 2 layer. The IDT electrode is preferably formed of at least one of Cu, Ag and Au, which is a metal having a higher density than Al, or an alloy containing one or more of these metals.
　なお、上記実施形態では、分波器の一種であるデュプレクサについて説明した。但し、本発明において、分波器は、デュプレクサに限定されない。分波器は、例えば、トリプレクサ等であってもよい。 In the above embodiment, a duplexer, which is a type of duplexer, has been described. However, in the present invention, the duplexer is not limited to a duplexer. The duplexer may be, for example, a triplexer.
　上記実施形態では、デュプレクサの受信側フィルタが平衡－不平衡変換機能を有する縦結合共振子型弾性波フィルタにより構成されており、送信側フィルタがラダー型の弾性波フィルタにより構成されている例について説明した。但し、本発明は、この構成に限定されない。本発明に係る分波器においては、分波器を構成する複数のフィルタのうち少なくともひとつのフィルタが、本発明を実施した、平衡－不平衡変換機能を有する弾性波フィルタにより構成されていればよい。例えば、送信側フィルタと受信側フィルタとの両方を、本発明を実施した、平衡－不平衡変換機能を有する弾性波フィルタにより構成してもよい。また、受信側フィルタのみを、本発明を実施した、平衡－不平衡変換機能を有する弾性波フィルタにより構成してもよい。 In the above embodiment, an example in which the reception filter of the duplexer is configured by a longitudinally coupled resonator type elastic wave filter having a balance-unbalance conversion function, and the transmission side filter is configured by a ladder type elastic wave filter. explained. However, the present invention is not limited to this configuration. In the duplexer according to the present invention, if at least one of the plurality of filters constituting the duplexer is configured by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention. Good. For example, both the transmission side filter and the reception side filter may be constituted by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention. Further, only the reception side filter may be constituted by an elastic wave filter having a balanced-unbalanced conversion function according to the present invention.
１…デュプレクサ
１０…アンテナ端子
１１…整合用インダクタ
１２…送信側信号端子
１３…送信側フィルタ
１４ａ～１４ｈ…交差部
１５…絶縁膜
２０…受信側フィルタ
２１…第１の受信側信号端子
２２…第２の受信側信号端子
２３…不平衡信号端子
２４…第１の平衡信号端子
２５…第２の平衡信号端子
２６…圧電基板
２７…接地用電極パッド
２８…弾性波フィルタ部
２９ａ…接地用電極パッド
２９ｂ…接地用電極パッド
３０…第１の縦結合共振子型弾性波フィルタ部
３１～３３…ＩＤＴ電極
３１ａ，３２ａ，３３ａ…第１のくし歯状電極
３１ｂ，３２ｂ，３３ｂ…第２のくし歯状電極
３４，３５…グレーティング反射器
４０…第２の縦結合共振子型弾性波フィルタ部
４１～４３…ＩＤＴ電極
４１ａ，４２ａ，４３ａ…第１のくし歯状電極
４１ｂ，４２ｂ，４３ｂ…第２のくし歯状電極
４４，４５…グレーティング反射器
５０…第３の縦結合共振子型弾性波フィルタ部
５１～５３…ＩＤＴ電極
５１ａ，５２ａ，５３ａ…第１のくし歯状電極
５１ｂ，５２ｂ，５３ｂ…第２のくし歯状電極
５４，５５…グレーティング反射器
６０…第４の縦結合共振子型弾性波フィルタ部
６１～６３…ＩＤＴ電極
６１ａ，６２ａ，６３ａ…第１のくし歯状電極
６１ｂ，６２ｂ，６３ｂ…第２のくし歯状電極
６４，６５…グレーティング反射器
７０，７１…弾性波共振子
７０ａ，７１ａ…ＩＤＴ電極
７０ａ１，７１ａ１…第１のくし歯状電極
７０ａ２，７１ａ２…第２のくし歯状電極
８１～８５…ＩＤＴ電極
８１ａ，８２ａ，８３ａ，８４ａ，８５ａ…第１のくし歯状電極
８１ｂ，８２ｂ，８３ｂ，８４ｂ，８５ｂ…第２のくし歯状電極
８６，８７…グレーティング反射器
９０…弾性境界波フィルタ
９１，９４，９５…誘電体層
９２…電極
９３…弾性境界波フィルタ DESCRIPTION OF SYMBOLS 1 ... Duplexer 10 ... Antenna terminal 11 ... Matching inductor 12 ... Transmission side signal terminal 13 ... Transmission side filter 14a-14h ... Intersection 15 ... Insulating film 20 ... Reception side filter 21 ... 1st reception side signal terminal 22 ... 1st 2 reception side signal terminals 23 ... unbalanced signal terminal 24 ... first balanced signal terminal 25 ... second balanced signal terminal 26 ... piezoelectric substrate 27 ... grounding electrode pad 28 ... elastic wave filter part 29a ... grounding electrode pad 29b... Ground electrode pad 30... First longitudinally coupled resonator type acoustic wave filter sections 31 to 33... IDT electrodes 31a, 32a, 33a... First comb electrodes 31b, 32b, 33b. -Like electrodes 34, 35 ... grating reflector 40 ... second longitudinally coupled resonator type acoustic wave filter sections 41 to 43 ... IDT electrodes 41a, 42a, 43a ... first comb- like electrode 41 , 42b, 43b, second comb-shaped electrodes 44, 45, grating reflector 50, third longitudinally coupled resonator type acoustic wave filter sections 51 to 53, IDT electrodes 51a, 52a, 53a, first comb teeth. -Like electrodes 51b, 52b, 53b ... second comb- like electrodes 54, 55 ... grating reflector 60 ... fourth longitudinally coupled resonator type acoustic wave filter sections 61 to 63 ... IDT electrodes 61a, 62a, 63a ... first Comb- like electrodes 61b, 62b, 63b ... second comb- like electrodes 64,65 ... grating reflectors 70,71 ... elastic wave resonators 70a, 71a ... IDT electrodes 70a1, 71a1 ... first comb-like electrodes 70a2, 71a2 ... second comb-like electrodes 81 to 85 ... IDT electrodes 81a, 82a, 83a, 84a, 85a ... first comb- like electrodes 81b, 82b, 83b, 84b 85b ... second comb-shaped electrodes 86, 87 ... grating reflectors 90 ... boundary acoustic wave filter 91,94,95 ... dielectric layer 92 ... electrode 93 ... boundary acoustic wave filter

Claims (3)

  1. 　不平衡信号端子と、
    　第１及び第２の平衡信号端子と、
    　圧電基板と、
    　前記圧電基板上において、前記不平衡信号端子と前記第１及び第２の平衡信号端子との間に接続されている弾性波フィルタ部と、
    　前記圧電基板上に形成されており、グラウンド電位に接続されている第１及び第２の接地用電極パッドとを備え、
    　前記弾性波フィルタ部は、前記圧電基板上に形成された複数のＩＤＴ電極からなり、
    　前記複数のＩＤＴ電極のうち、少なくとも一つのＩＤＴ電極は、前記不平衡信号端子に接続されている少なくとも一つのくし歯状電極を有する不平衡信号端子側ＩＤＴ電極であり、
    　前記複数のＩＤＴ電極のうちの少なくとも一つのＩＤＴ電極は、前記第１の平衡信号端子に接続されている少なくとも一つのくし歯状電極と、前記第１の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する第１の平衡信号端子側ＩＤＴ電極であり、
    　前記複数のＩＤＴ電極のうちの少なくとも一つのＩＤＴ電極は、前記第２の平衡信号端子に接続されている少なくとも一つのくし歯状電極と、前記第２の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する第２の平衡信号端子側ＩＤＴ電極であり、
    　前記第１の平衡信号端子側ＩＤＴ電極と、前記第２の平衡信号端子側ＩＤＴ電極とは、弾性波の伝搬方向に直行する方向を対称軸として、反転した構成とされている、弾性波フィルタ。     An unbalanced signal terminal;
    First and second balanced signal terminals;
    A piezoelectric substrate;
    On the piezoelectric substrate, an elastic wave filter unit connected between the unbalanced signal terminal and the first and second balanced signal terminals;
    First and second grounding electrode pads formed on the piezoelectric substrate and connected to a ground potential;
    The acoustic wave filter unit is composed of a plurality of IDT electrodes formed on the piezoelectric substrate,
    Of the plurality of IDT electrodes, at least one IDT electrode is an unbalanced signal terminal side IDT electrode having at least one comb-like electrode connected to the unbalanced signal terminal,
    At least one IDT electrode of the plurality of IDT electrodes includes at least one comb-like electrode connected to the first balanced signal terminal and at least connected to the first ground electrode pad. A first balanced signal terminal side IDT electrode having one comb-like electrode;
    At least one IDT electrode of the plurality of IDT electrodes is at least one comb-like electrode connected to the second balanced signal terminal and at least connected to the second ground electrode pad. A second balanced signal terminal side IDT electrode having one comb-like electrode;
    An elastic wave filter in which the first balanced signal terminal side IDT electrode and the second balanced signal terminal side IDT electrode are inverted with respect to a direction orthogonal to an elastic wave propagation direction. .
  2. 　前記圧電基板上に形成されており、グラウンド電位に接続されている第３の接地用電極パッドをさらに備え、
    　前記複数のＩＤＴ電極のうち、前記第１の平衡信号端子側ＩＤＴ電極と前記第２の平衡信号端子側ＩＤＴ電極以外のＩＤＴ電極は、前記第３の接地用電極パッドに接続されている少なくとも一つのくし歯状電極とを有する、請求項１に記載の弾性波フィルタ。     A third grounding electrode pad formed on the piezoelectric substrate and connected to a ground potential;
    Of the plurality of IDT electrodes, at least one IDT electrode other than the first balanced signal terminal side IDT electrode and the second balanced signal terminal side IDT electrode is connected to the third ground electrode pad. The elastic wave filter according to claim 1, comprising two comb-like electrodes.
  3. 　請求項１または２に記載の弾性波フィルタを備える、分波器。 A duplexer comprising the elastic wave filter according to claim 1.
PCT/JP2010/060723 2009-11-26 2010-06-24 Acoustic wave filter and branching filter WO2011065048A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002314371A (en) * 2001-04-18 2002-10-25 Murata Mfg Co Ltd Surface acoustic wave filter device and communication equipment
JP2004088551A (en) * 2002-08-28 2004-03-18 Murata Mfg Co Ltd Surface acoustic wave device and communication equipment
JP2007312201A (en) * 2006-05-19 2007-11-29 Kyocera Corp Board mounting type surface acoustic wave device and manufacturing method therefor, and communication equipment

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002314371A (en) * 2001-04-18 2002-10-25 Murata Mfg Co Ltd Surface acoustic wave filter device and communication equipment
JP2004088551A (en) * 2002-08-28 2004-03-18 Murata Mfg Co Ltd Surface acoustic wave device and communication equipment
JP2007312201A (en) * 2006-05-19 2007-11-29 Kyocera Corp Board mounting type surface acoustic wave device and manufacturing method therefor, and communication equipment

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