JP2019121879A - Multiplexer - Google Patents

Abstract

To provide a multiplexer with an excellent characteristic.SOLUTION: A multiplexer comprises: a first piezoelectric substrate as a lithium tantalate substrate or a lithium niobate substrate; a second piezoelectric substrate as the lithium tantalate substrate and the lithium niobate substrate; a ladder filter connected to between a common terminal and a first terminal, and including a plurality of resonator having a first IDT formed by a first metal film provided onto the first piezoelectric substrate; and a multiple mode filter connected to between the common terminal and a second terminal, including a passing band higher than that of the ladder filter, formed by a second metal film provided onto the second piezoelectric substrate, and including a plurality of second IDTs of which an average pitch of a grating electrode of at least one second IDT is larger than the average pitch of the grating electrode of at least one first IDT of the plurality of resonator.SELECTED DRAWING: Figure 7

Description

  The present invention relates to multiplexers, for example multiplexers with grating electrodes.

  2. Description of the Related Art In a system for high frequency communication represented by a mobile phone, a high frequency filter or the like is used in order to remove unnecessary signals other than frequency bands used for communication. An elastic wave device having a surface acoustic wave (SAW) element or the like is used as a high frequency filter or the like. The SAW element is an element in which a grating electrode such as an IDT (Interdigital Transducer) is formed on a piezoelectric substrate. It is known to reduce the loss by setting the sound velocity of the surface acoustic wave excited by the grating electrode slower than the sound velocity of the bulk wave propagating in the piezoelectric substrate (for example, Patent Document 1).

JP, 2016-136712, A

  In the multiplexer, a low loss, wide band filter with excellent attenuation characteristics is required. However, the configuration of a filter suitable for the multiplexer is not known.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multiplexer having excellent characteristics.

  The present invention provides an electrical connection between a first piezoelectric substrate, which is a lithium tantalate substrate or a lithium niobate substrate, a second piezoelectric substrate, which is a lithium tantalate substrate or a lithium niobate substrate, and a common terminal and a first terminal. A ladder type filter including a plurality of resonators having a first IDT connected to the first piezoelectric substrate and connected to the first piezoelectric substrate, and electrically connected between the common terminal and the second terminal Of the grating electrodes of at least one second IDT formed of a second metal film provided on the second piezoelectric substrate and having a passband higher than that of the ladder type filter A multi-mode filter having a plurality of second IDTs larger than an average pitch of at least one first IDT grating electrode of the plurality of resonators; It is a mux.

  According to the present invention, a first metal film electrically connected between a common terminal and a first terminal and provided on a single piezoelectric substrate which is a lithium tantalate substrate or a lithium niobate substrate and provided on the piezoelectric substrate And a ladder-type filter including a plurality of resonators having a first IDT formed by the first IDT and electrically connected between the common terminal and the second terminal, and having a passband higher than a passband of the ladder-type filter A plurality of second metal films provided on the piezoelectric substrate, wherein an average pitch of grating electrodes of at least one second IDT is larger than an average pitch of grating electrodes of at least one first IDT of the plurality of resonators; A multi-mode filter having a second IDT.

  In the above configuration, a first wiring in which the plurality of resonators are electrically connected and the first metal film and the second metal film are laminated at least in part, the multimode filter, the common terminal, and And / or the second wiring may be electrically connected to the second terminal, and a second wiring in which the first metal film and the second metal film are stacked at least in part may be provided.

  In the above configuration, the acoustic impedance of the grating electrode of the second IDT can be smaller than the acoustic impedance of the grating electrode of the first IDT.

  In the above configuration, the acoustic impedance of the grating electrode of the second IDT may be half or less of the acoustic impedance of the grating electrode of the first IDT.

  In the above configuration, the first metal film may include a metal film containing at least one of Cu, W, Ru, Mo, Ta, Pt, Pd, Ir, Rh, Re, and Te as a main component. it can.

  In the above configuration, the second metal film can include a metal film containing Al as a main component.

  In the above configuration, the elastic wave excited by the grating electrode of the first IDT and the grating electrode of the second IDT may be a SH wave.

  In the above configuration, the piezoelectric substrate may be a Y-cut X-propagation lithium tantalate substrate having a cut angle of 20 ° or more and 48 ° or less.

  In the above configuration, the first metal film is formed of one or more stacked third metal films, and the density of each third metal film of the one or more third metal films is ρi, and each of the third metal films is Assuming that the Poisson's ratio of the metal film is Pi, the film thickness of each of the third metal films is hi, the density of Cu is 00, the Poisson's ratio of Cu is P0, and the average pitch of the grating electrodes of the first IDT is λ. The sum of (hi / λ) × (ρi / ρ0) × (Pi / P0) in each of the third metal films for the one or more third metal films may be greater than 0.08.

  According to the present invention, a multiplexer with excellent characteristics can be provided.

FIG. 1 is a circuit diagram of a multiplexer according to the first embodiment. Fig.2 (a) is a top view which shows the elastic wave resonator used for the transmission filter in Example 1, FIG.2 (b) is AA sectional drawing of Fig.2 (a). FIG. 3A is a plan view showing a multimode filter used for the reception filter in the first embodiment, and FIG. 3B is a cross-sectional view taken along the line A-A of FIG. FIG. 4A shows the pass characteristic of the multimode filter in Comparative Example 1, and FIG. 4B shows the imaginary part Im | Y | of admittance. FIG. 5A is a view showing the pass characteristic of the multimode filter in the first embodiment, and FIG. 5B is a view showing an imaginary part Im | Y | of admittance. FIGS. 6A to 6C are cross-sectional views of resonators according to first to third modifications of the first embodiment, respectively. FIGS. 7A and 7B are plan views of the transmission filter and the reception filter in the second embodiment, respectively. FIG. 8 is a plan view of the transmission filter and the reception filter in the first modification of the second embodiment. Fig.9 (a) is a top view of the transmission filter based on the modification 2 of Example 2, and a receiving filter, FIG.9 (b) is AA sectional drawing of Fig.9 (a). Fig.10 (a) is a top view of the transmission filter based on the modification 3 of Example 2, and a receiving filter, FIG.10 (b) is AA sectional drawing of Fig.10 (a).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram of a multiplexer according to the first embodiment. As shown in FIG. 1, a transmission filter 40 is connected between the common terminal Ant and the transmission terminal Tx. A reception filter 42 is connected between the common terminal Ant and the reception terminal Rx.

  The transmission filter 40 is a ladder type filter, and includes series resonators S1 to S5 and parallel resonators P1 to P4. The series resonators S1 to S5 are connected in series in a path between the common terminal Ant and the transmission terminal Tx. The parallel resonators P1 to P4 each have one end connected to the path between the common terminal Ant and the transmission terminal Tx, and the other end connected to the ground terminal. The number of series resonators S1 to S5 and parallel resonators P1 to P4 are set to have desired characteristics. The reception filter 42 is a longitudinally coupled multimode filter DMS. The multimode filter is, for example, a dual mode filter.

  Among the high frequency signals input from the transmission terminal Tx, the transmission filter 40 passes the signal of the transmission band to the common terminal Ant and suppresses the signals of other frequencies. The reception filter 42 passes the signal of the reception band among the high frequency signals input from the common terminal Ant to the reception terminal Rx and suppresses the signals of other frequencies. The transmit band and the receive band do not overlap. In this example, the transmission band is lower than the reception band. Therefore, the transmission filter 40 is required to have a large amount of attenuation in the reception band higher in frequency than the pass band. The reception filter 42 is required to have a large amount of attenuation in a transmission band lower than the communication band. Therefore, a ladder type filter is used as the transmission filter 40, and a multi-mode filter is used as the reception filter 42. When the transmission band is higher than the reception band, a ladder type filter is used as a reception filter, and a multiplex mode filter is used as a transmission filter. That is, a filter with low pass characteristics is a ladder type filter, and a filter with high pass characteristics is a multi-mode filter.

  Fig.2 (a) is a top view which shows the elastic wave resonator used for the transmission filter in Example 1, FIG.2 (b) is AA sectional drawing of Fig.2 (a). As shown in FIGS. 2A and 2B, the elastic wave resonator 20 has an IDT 12 and a reflector 14. The IDT 12 and the reflector 14 are provided on the piezoelectric substrate 10a. The piezoelectric substrate 10a is a lithium tantalate substrate or a lithium niobate substrate. The IDT 12 and the reflector 14 are formed of the metal film 11a. The IDT 12 has a pair of comb electrodes 18. The pair of comb-shaped electrodes 18 each have a plurality of electrode fingers 16 and a bus bar 15 to which the plurality of electrode fingers 16 are connected. The electrode fingers 16 of the pair of comb electrodes 18 form a grating electrode. The electrode fingers 16 of one comb electrode 18 and the electrode fingers 16 of the other comb electrode 18 are alternately provided at least in part. The reflectors 14 are formed on both sides of the IDT 12 in the propagation direction of the elastic wave. The reflector 14 reflects the elastic wave. The film thickness of the metal film 11a is T1, and the pitch of the grating electrodes (pitch of the electrode fingers 16 in the same comb electrode 18) is λ1. λ1 corresponds to the wavelength of the surface acoustic wave that the IDT 12 excites.

  When the sound velocity of the surface acoustic wave excited by the IDT 12 is faster than the sound velocity of the bulk wave (for example, the slowest shear bulk wave) propagating in the piezoelectric substrate 10a, the surface acoustic wave propagates the surface of the piezoelectric substrate while emitting the bulk wave. Do. Thus, losses occur. In particular, the sound velocity of a SH (Shear Horizontal) wave, which is a type of surface acoustic wave, is faster than the sound velocity of bulk waves. For this reason, in the elastic wave resonator 20 having the SH wave as the main mode, the loss is large. For example, in a Y-cut X-propagation lithium tantalate substrate having a cut angle of 20 ° or more and 48 ° or less, the SH wave is the main mode.

In order to slow the sound velocity of the surface acoustic wave, a metal having a large acoustic impedance is used for the metal film 11a, and the metal film 11a is thickened. The acoustic impedance Z is represented by the following equation, where density is 密度, Young's modulus is E, and Poisson's ratio is Pr.

Table 1 is a table showing the density, Young's modulus, Poisson's ratio and acoustic impedance of Cu (copper), W (tungsten), Ru (ruthenium), Mo (molybdenum) and Al (aluminum). As shown in Table 1, the acoustic impedance of Cu, W, Ru and Mo is at least twice that of Al.

  For example, when the piezoelectric substrate 10a is an X-propagating lithium tantalate substrate having a cut angle of 20 ° or more and 48 ° or less and the metal film 11a contains Mo or Cu as a main component, T1 / λ1> 0.08 . When the metal film 11 a contains W as a main component, T1 / λ1> 0.05. When the metal film 11a contains Ru as a main component, T1 / λ1> 0.07. As a result, the sound velocity of the SH wave becomes slower than the sound velocity of the bulk wave, resulting in low loss.

  FIG. 3A is a plan view showing a multimode filter used for the reception filter in the first embodiment, and FIG. 3B is a cross-sectional view taken along the line A-A of FIG. As shown in FIGS. 3A and 3B, the multimode filter DMS has IDTs 12a to 12c and a reflector. The IDTs 12a to 12c and the reflector 14 are provided on the piezoelectric substrate 10b. The piezoelectric substrate 10 b is a lithium tantalate substrate or a lithium niobate substrate. The structure of the IDTs 12a to 12c is the same as that of the IDT 12 and the description thereof is omitted. The IDTs 12a to 12c are arranged in the propagation direction of the surface acoustic wave. A reflector 14 is provided outside the IDTs 12a to 12c. The IDTs 12a to 12c and the reflector 14 are formed of a metal film 11b.

  One end of the IDT 12 b is connected to the input terminal Tin (the common terminal Ant in FIG. 1), and the other end is connected to the ground terminal. One end of the IDT 12a and one end of the IDT 12c are commonly connected to the output terminal Tout (the reception terminal Rx in FIG. 1). The other end of the IDT 12a and the other end of the IDT 12c are connected to the ground terminal. The film thickness of the metal film 11b is T2, and the pitch of the grating electrodes is λ2. λ2 corresponds to the wavelength of the surface acoustic wave excited by the IDTs 12a to 12c.

  The pass characteristics of Example 1 in which the metal film 11 b was Al film and Comparative Example 1 in which the Mo film was Mo film were simulated using the finite element method. The simulations were performed on a multimode filter with two IDTs 12a and 12b.

The simulation conditions are as follows.
Log of IDT 12a: 30 vs. log of IDT 12b: 30 vs log of reflector 14 (per piece): 10 vs. Piezoelectric substrate 10b: 42 ° Y cut X-propagation lithium tantalate material of metal film 11b: Al (Example 1) , Mo (comparative example 1)
Thickness T2 / λ2 of the metal film 11b: 0.1
Pitch λ2: 5.0 μm

  FIG. 4A shows the pass characteristic of the multimode filter in Comparative Example 1, and FIG. 4B shows the imaginary part Im | Y | of admittance. As shown in FIG. 4A, in Comparative Example 1, the relative bandwidth Δf is 2.8%. The fractional bandwidth is the ratio of the width of the passband to the center of the passband. As shown in FIG. 4B, the difference .DELTA.f 'between the resonance frequencies (white circles) of the solid even (secondary) mode and the broken odd (first) mode is small.

  FIG. 5A is a view showing the pass characteristic of the multimode filter in the first embodiment, and FIG. 5B is a view showing an imaginary part Im | Y | of admittance. As shown in FIG. 5A, in the first embodiment, the relative bandwidth Δf is 3.5%. As shown in FIG. 5B, the difference .DELTA.f 'between the resonance frequencies (white circles) of the even mode in the solid line and the odd mode in the broken line is larger than that in the first comparative example in FIG. 4B. As a result, the relative bandwidth Δf of the first embodiment is larger than that of the first comparative example.

  The fractional bandwidth requirement of the filter for a cellular phone system is 3% to 4%, and in Comparative Example 1, the fractional bandwidth is too small. The relative bandwidth is small in Comparative Example 1 because the difference in resonance frequency between the even mode and the odd mode is small. This is considered to be because the reflection coefficient of the surface acoustic wave by the grating electrode in Comparative Example 1 is too large. For example, the reflection coefficient 1212 per unit length of the shorted grating electrode in Comparative Example 1 is 0.54 when calculated by the finite element method. The reflection coefficient 1212 is determined by the difference between the acoustic impedance of the region where the electrode finger 16 of the grating electrode is provided and the acoustic impedance where the electrode finger 16 is not formed. Therefore, when the acoustic impedance of the grating electrode is large, the reflection coefficient κ12 is large.

  In Example 1, Al having a small acoustic impedance as shown in Table 1 is used as the metal film 11 b. The reflection coefficient 1212 of the first embodiment is 0.2. As a result, it is considered that the relative bandwidth Δf of the first embodiment is increased. The above simulation was performed for a multimode filter with two IDTs, but if using a multimode filter with three IDTs and using a combined multimode filter with a primary mode and a third mode, the relative bandwidth Δf is 4% or more Is possible.

  Thus, in the first embodiment, the transmission filter 40 uses the metal film 11 a having a large acoustic impedance. Thereby, the loss of the transmission filter 40 can be reduced. For example, when the piezoelectric substrate 10a is a lithium tantalate substrate, the velocity of sound of bulk shear wave is 3400 m / s. Therefore, the material and the film thickness of the metal film 11a are set so that the sound velocity of the surface acoustic wave is 3200 m / s or less. For example, the metal film 11a is a Mo film having a film thickness of 0.1 × λ1. For example, in the transmission filter 40 for the transmission band 703 MHz to 733 MHz of the LTE band 28, λ1 is set to about 4.36 μm to 4.55 μm.

  The reception filter 42 uses the metal film 11 b having a small acoustic impedance. Thereby, the relative bandwidth of the reception filter 42 can be increased. For example, the metal film 11b is an Al film having a film thickness of 0.1 × λ2. The reception band of the LTE band 28 is set to 5.07 μm to 5.27 μm in the reception filter 42 for 758 MHz to 788 MHz.

  Further, by setting the transmission filter 40 as a ladder type filter, the steepness on the high frequency side of the pass band can be enhanced. Therefore, the attenuation characteristic of the transmission filter 40 in the reception band can be improved. By setting the reception filter 42 as a multimode filter, the steepness on the low frequency side of the passband can be enhanced. Therefore, it is possible to improve the attenuation characteristics of the reception filter in the transmission band.

[Modifications 1 to 3 of Embodiment 1]
FIGS. 6A to 6C are cross-sectional views of resonators according to first to third modifications of the first embodiment, respectively. As shown in FIG. 6A, a dielectric film 24 is formed on the piezoelectric substrates 10a and / or 10b so as to cover the metal films 11a and / or 11b. The dielectric film 24 is a film for frequency adjustment and / or temperature change compensation. As the dielectric film 24, for example, a silicon oxide film, a silicon nitride film, or an aluminum oxide film can be used. The piezoelectric substrates 10a and 10b may be bonded onto a supporting substrate such as a silicon substrate, a sapphire substrate, an alumina substrate, a spinel substrate, a glass substrate, or a quartz substrate.

  As shown in FIG. 6B, an adhesion layer 13 may be formed between the metal films 11a and / or 11b and the piezoelectric substrate 10a and / or 10b. The adhesion layer 13 is a film for improving the adhesion between the metal films 11a and / or 11b and the piezoelectric substrate 10a and / or 10b. For example, Ti (titanium) or Cr (chromium) can be used as the adhesion layer 13. The material of the adhesion layer 13 is lighter and thinner than the metal films 11a and / or 11b. Therefore, the presence or absence of the adhesion layer 13 hardly affects the acoustic impedance of the grating electrode.

As shown in FIG. 6C, in the metal films 11a and / or 11b, a plurality of metal films 11c and 11d may be stacked. In this case, the acoustic impedance _{Z all} of the metal film 11a or 11b is the acoustic impedance _Z i of the i-th layer of the metal film, film thickness _{t i} of the i-th layer of the metal film, the thickness of the metal film 11a or 11b _Assuming that t _all , it is represented by the number 2. The film thickness t _i corresponds to the film thicknesses h 1 and h 2 of the metal films 11 a and 11 b, and the film thickness t _all corresponds to the film thickness T 1 or T 2.

  According to the first embodiment, the ladder type filter is electrically connected between the common terminal Ant and the transmission terminal Tx (first terminal), and the series resonators S1 to S5 and the parallel resonators P1 to P4 (resonators )including. An IDT 12 (a first metal film) formed on a piezoelectric substrate 10a (a first piezoelectric substrate) and at least one of the series resonators S1 to S5 and the parallel resonators P1 to P4 is an IDT 12 (a first metal film). Have a first IDT). The multi-mode filter DMS is electrically connected between the common terminal Ant and the reception terminal Rx (second terminal), and is a metal film 11 b (second metal film) provided on the piezoelectric substrate 10 b (second piezoelectric substrate). And a plurality of IDTs 12a to 12c (second IDTs). The multimode filter has a higher passband than the passband of the ladder filter.

  If the passband of the multimode filter is higher than the passband of the ladder type filter, all of the average pitches λ2 of the grating electrodes of the IDTs 12a to 12c of the multimode filter are series resonators S1 to S5 of the ladder type filter and parallel resonator P1. It is common sense to be smaller than the average pitch λ1 of the grating electrodes of all IDTs 12 to P4.

  However, in the multiplexer as described above, the acoustic impedance of the metal film 11a is increased in order to reduce the loss of the ladder type filter, and the acoustic impedance of the metal film 11b is reduced in order to widen the multimode filter. The sound velocity of the surface acoustic wave excited by the first grating electrode formed of the metal film 11a is delayed. Therefore, the average pitch λ2 of the grating electrodes of at least one of the IDTs 12a to 12c of the multimode filter is the grating electrodes of the IDTs 12 of the series resonators S1 to S5 of the ladder filter and the parallel resonators P1 to P4. It becomes larger than average pitch λ1. The average pitch of the IDT is a value obtained by dividing the width of the IDT in the propagation direction of the surface acoustic wave by the logarithm of the electrode finger 16.

  The average pitch λ2 is preferably 1.05 times or more of the average pitch λ1 and more preferably 1.1 times or more.

  In order to lower the loss of the ladder filter and broaden the bandwidth of the multimode filter, the average pitch λ2 of the grating electrodes of all the IDTs 12a to 12c of the multimode filter corresponds to series resonators S1 to S5 and parallel resonance of the ladder filter. It is preferable that the average pitch λ1 of the grating electrodes of the IDTs 12 of all the resonators P1 to P4 be larger than the average pitch λ1.

  The acoustic impedance of the grating electrodes of the IDTs 12 a to 12 c is smaller than the acoustic impedance of the grating electrodes of the IDT 12. As a result, the ladder filter can be further reduced in loss, and the multi-mode filter can be broadened in bandwidth. The acoustic impedance of the grating electrodes of the IDTs 12 a to 12 c is preferably 1/2 or less, more preferably 1/3 or less of the acoustic impedance of the grating electrodes of the IDT 12.

  When a plurality of metal films of different materials in which the metal films 11a and / or 11b are stacked is included, the acoustic impedance of the metal films 11a and / or 11b can be calculated from Equation 2.

  The film thickness T2 of the metal film 11b is preferably 0.5 times or more and 1.5 times or less of the film thickness T1 of the metal film 11a, and more preferably 0.8 times or more and 1.2 times or less.

  As a material having a large acoustic impedance, the metal film 11a is made of Cu, W, Ru, Mo, Ta (tantalum), Pt (platinum), Pd (palladium), Ir (iridium), Rh (rhodium), Re (rhenium) and It is preferable to include a metal film containing at least one of Te (tellurium) as a main component. It is preferable that the metal film 11 b includes a metal film containing Al as a main component as a material having a small acoustic impedance. The fact that the metal film contains an element as a main component means that the metal film contains the element to the extent that the effect of Example 1 can be obtained. For example, the atomic concentration of the element in the metal film is 50% or more, preferably 80% or more More preferably, it is 90% or more. For example, the metal film 11b may be Al containing several atomic percent of Cu.

  The elastic waves excited by the grating electrodes of the IDTs 12 and 12a to 12c are mainly SH waves. The sound velocity of the SH wave is larger than that of the bulk wave, so the loss is large. Therefore, it is preferable to make the average pitch λ2 larger than the average pitch λ1.

  As described in Patent Document 1, when the piezoelectric substrate 10a and the piezoelectric substrate 10b are Y-cut X-propagating lithium tantalate substrates having a cut angle of 20 ° or more and 48 ° or less, the surface acoustic wave to be excited is SH Become a wave.

  As described in Patent Document 1, when the piezoelectric substrate 10a is a Y-cut X-propagation lithium tantalate substrate having a cut angle of 20 ° or more and 48 ° or less, the metal film 11a is one or a plurality of laminated metals. It is formed of a film (third metal film). At this time, of the one or more third metal films, the density of each third metal film is ρi, the Poisson's ratio of each third metal film is Pi, the film thickness of each third metal film is hi, the density of Cu is ρ0 , Where Cu is Poisson's ratio P0 and the average pitch is λ1, (hi / λ) × (ρi / ρ0) × (Pi / P0) in each third metal film is one or a plurality of third metal films Make the total value greater than 0.08. Thereby, the sound velocity of the SH wave can be made slower than the sound velocity of the bulk wave, and the loss can be reduced.

  FIGS. 7A and 7B are plan views of the transmission filter and the reception filter in the second embodiment, respectively. As shown in FIG. 7A, in the transmission filter 40, series resonators S1 to S5 and parallel resonators P1 to P4 are provided as the elastic wave resonator 20 on the piezoelectric substrate 10a. The elastic wave resonators 20 are electrically connected by the wiring 22a. The wiring 22a includes the metal film 11a. In the wiring 22a, a metal film having a low resistivity such as an Au film or a Cu film may be stacked on the metal film 11a. The common terminal Ant1, the transmission terminal Tx, and the ground terminal GND are formed by the wiring 22a.

  As shown in FIG. 7B, in the reception filter 42, the multimode filter DMS is provided on the piezoelectric substrate 10b. The common terminal Ant2, the reception terminal Rx, and the ground terminal GND are formed by the wiring 22b. The common terminal Ant2, the reception terminal Rx, the ground terminal GND, and the IDTs 12a to 12c are electrically connected by the wiring 22b. The interconnection 22b includes the metal film 11b. The wiring 22b may be formed by laminating a metal film having a low resistivity, such as an Au film or a Cu film, on the metal film 11b. The common terminals Ant1 and Ant2 are connected outside the piezoelectric substrates 10a and 10b. The other configuration is the same as that of the first embodiment, and the description is omitted.

  As in the second embodiment, the transmission filter 40 and the reception filter 42 may be provided on different piezoelectric substrates 10 a and 10 b. One of the piezoelectric substrates 10a and 10b may be a lithium tantalate substrate, and the other may be a lithium niobate substrate. The piezoelectric substrates 10a and 10b may both be lithium tantalate substrates or lithium niobate substrates.

Modification 1 of Embodiment 2
FIG. 8 is a plan view of the transmission filter and the reception filter in the first modification of the second embodiment. As shown in FIG. 8, the transmission filter 40 and the reception filter 42 are provided on a single piezoelectric substrate 10. As described above, in the case where the first piezoelectric substrate and the second piezoelectric substrate are the single piezoelectric substrate 10, widening the bandwidth of the multimode filter becomes difficult when attempting to reduce the sound velocity of the surface acoustic wave in the ladder type filter. Therefore, it is preferable to make λ2 larger than λ1. The other configuration is the same as that of the second embodiment and the description will be omitted.

[Modification 2 of Embodiment 2]
Fig.9 (a) is a top view of the transmission filter based on the modification 2 of Example 2, and a receiving filter, FIG.9 (b) is AA sectional drawing of Fig.9 (a). As shown in FIG. 9A, the common terminal Ant is provided on the piezoelectric substrate 10. As shown in FIG. 9B, the wiring 22a and the IDT 12 are formed by the metal film 11a, and the wiring 22b and the IDTs 12a to 12c are formed by the metal film 11b. The other configuration is the same as that of the first modification of the second embodiment, and the description thereof is omitted.

Modification 3 of Embodiment 2
Fig.10 (a) is a top view of the transmission filter based on the modification 3 of Example 2, and a receiving filter, FIG.10 (b) is AA sectional drawing of Fig.10 (a). As shown in FIGS. 10A and 10B, the IDT 12 is formed of a metal film 11a, and the IDTs 12a to 12c are formed of a metal film 11b. The wirings 22a and 22b are formed by laminating the metal film 11a and the metal film 11b. The other configuration is the same as that of the second modification of the second embodiment, and the description thereof is omitted.

  The wiring 22a (first wiring) electrically connects the series resonators S1 to S5 and the parallel resonators P1 to P4, and the metal films 11a and 11b are stacked at least in part. The wiring 22b (second wiring) electrically connects the multimode filter DMS to the common terminal Ant and / or the receiving terminal Rx, and the metal films 11a and 11b are laminated at least in part. Thereby, the resistances of the interconnections 22a and 22b can be reduced without adding an extra manufacturing process.

  As mentioned above, although the embodiment of the present invention has been described in detail, the present invention is not limited to such a specific embodiment, and various modifications may be made within the scope of the subject matter of the present invention described in the claims. Changes are possible.

10, 10a, 10b Piezoelectric substrate 11a, 11b Metal film 12, 12a-12c IDT
14 reflector 16 electrode finger 18 comb-shaped electrode 20 elastic wave resonator 22a, 22b wiring 40 transmission filter 42 reception filter

Claims (10)

A first piezoelectric substrate which is a lithium tantalate substrate or a lithium niobate substrate;
A second piezoelectric substrate which is a lithium tantalate substrate or a lithium niobate substrate;
A ladder type filter including a plurality of resonators having a first IDT electrically connected between the common terminal and the first terminal and formed by the first metal film provided on the first piezoelectric substrate;
It is electrically connected between the common terminal and the second terminal, has a pass band higher than that of the ladder type filter, and is formed of a second metal film provided on the second piezoelectric substrate, A multimode filter having a plurality of second IDTs, wherein the average pitch of the grating electrodes of the at least one second IDT is greater than the average pitch of the grating electrodes of the at least one first IDT of the plurality of resonators;
With a multiplexer. A single piezoelectric substrate which is a lithium tantalate substrate or a lithium niobate substrate;
A ladder type filter including a plurality of resonators having a first IDT electrically connected between the common terminal and the first terminal and formed by the first metal film provided on the piezoelectric substrate;
At least one of a second metal film electrically connected between the common terminal and the second terminal, having a pass band higher than the pass band of the ladder type filter, and provided on the piezoelectric substrate; A multimode filter having a plurality of second IDTs, wherein the average pitch of the grating electrodes of the second IDTs is larger than the average pitch of the grating electrodes of the at least one first IDT of the plurality of resonators;
With a multiplexer. A first wiring which electrically connects the plurality of resonators and in which the first metal film and the second metal film are laminated at least in part;
A second wiring in which the multimode filter is electrically connected to the common terminal and / or the second terminal, and the first metal film and the second metal film are stacked at least in part;
The multiplexer according to claim 2, comprising   The multiplexer according to any one of claims 1 to 3, wherein an acoustic impedance of a grating electrode of the second IDT is smaller than an acoustic impedance of a grating electrode of the first IDT.   The multiplexer according to any one of claims 1 to 3, wherein an acoustic impedance of a grating electrode of the second IDT is equal to or less than 1/2 of an acoustic impedance of a grating electrode of the first IDT.   The first metal film according to any one of claims 1 to 5, wherein the first metal film includes a metal film containing at least one of Cu, W, Ru, Mo, Ta, Pt, Pd, Ir, Rh, Re and Te as a main component. Multiplexer described in the section.   The multiplexer according to claim 6, wherein the second metal film includes a metal film containing Al as a main component.   The multiplexer according to any one of claims 1 to 7, wherein elastic waves excited by the grating electrode of the first IDT and the grating electrode of the second IDT are SH waves.   The multiplexer according to claim 2, wherein the piezoelectric substrate is a Y-cut X-propagation lithium tantalate substrate having a cut angle of 20 ° or more and 48 ° or less.   The first metal film is formed of one or more stacked third metal films, and the density of each third metal film among the one or more third metal films is ρi, and Poisson of each third metal film is When the ratio is Pi, the film thickness of each third metal film is hi, the density of Cu is 00, the Poisson's ratio of Cu is P0, and the average pitch of the grating electrodes of the first IDT is λ, each third metal 10. The multiplexer according to claim 9, wherein the sum of (hi / [lambda]) * ([rho] i / [rho] 0) * (Pi / P0) in the film for said one or more third metal films is greater than 0.08.

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