WO2022009692A1 - Multiplexer - Google Patents

Multiplexer Download PDF

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Publication number
WO2022009692A1
WO2022009692A1 PCT/JP2021/024085 JP2021024085W WO2022009692A1 WO 2022009692 A1 WO2022009692 A1 WO 2022009692A1 JP 2021024085 W JP2021024085 W JP 2021024085W WO 2022009692 A1 WO2022009692 A1 WO 2022009692A1
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Prior art keywords
filter
elastic wave
resonator
common terminal
electrode fingers
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PCT/JP2021/024085
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French (fr)
Japanese (ja)
Inventor
知久 小村
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株式会社村田製作所
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Application filed by 株式会社村田製作所 filed Critical 株式会社村田製作所
Priority to CN202190000609.2U priority Critical patent/CN219247815U/en
Publication of WO2022009692A1 publication Critical patent/WO2022009692A1/en

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

Definitions

  • Patent Document 1 discloses as such a multiplexer, a multiplexer composed of a plurality of filters including an elastic wave filter having a leaky wave as a main mode.
  • an object of the present invention is to provide a multiplexer or the like capable of suppressing deterioration of insertion loss in the pass band due to Rayleigh wave ripple of elastic wave resonators.
  • FIG. 1 is a configuration diagram showing an example of a multiplexer according to an embodiment.
  • FIG. 2 is a circuit configuration diagram showing an example of the first filter according to the embodiment.
  • FIG. 3 is a plan view and a cross-sectional view schematically showing the electrode configuration of the elastic wave resonator according to the embodiment.
  • FIG. 4 is a graph showing the relationship between the logarithm and the return loss of the Rayleigh wave ripple.
  • FIG. 5 is a graph showing the relationship between the wavelength ratio and the return loss of Rayleigh wave ripple.
  • FIG. 6 is a graph showing the relationship between IRGAP and the return loss of Rayleigh wave ripple.
  • FIG. 7 is a graph showing the passing characteristics of the first filter according to the comparative example.
  • FIG. 1 is a configuration diagram showing an example of a multiplexer according to an embodiment.
  • FIG. 2 is a circuit configuration diagram showing an example of the first filter according to the embodiment.
  • FIG. 3 is a plan view and a cross-sectional view schematically
  • FIG. 8 is a graph showing the return loss characteristics seen from the common terminal side of the first filter according to the comparative example.
  • FIG. 9 is a graph comparing the return loss characteristics seen from the common terminal side of the first filter according to the example and the comparative example.
  • FIG. 10 is a graph showing the gain characteristics of the amplifier circuit connected to the second filter according to the example and the comparative example.
  • FIG. 11 is a circuit configuration diagram showing a modified example of the first filter according to the embodiment.
  • FIG. 12 is a circuit configuration diagram showing a modified example of the first filter according to the embodiment.
  • the multiplexer 1 is a demultiplexing / combining circuit using an elastic wave filter.
  • the multiplexer 1 includes a common terminal 3 and input / output terminals 4a and 4b as input / output terminals.
  • the input / output terminal 4a is an example of a first input / output terminal
  • the input / output terminal 4b is an example of a second input / output terminal.
  • the multiplexer 1 includes filters 2a and 2b, and one side of each (a side different from the input / output terminals 4a and 4b side) is commonly connected to the common terminal 3.
  • the input / output terminal 4a is provided corresponding to the filter 2a and is connected to the filter 2a inside the multiplexer 1.
  • the input / output terminal 4b is provided corresponding to the filter 2b and is connected to the filter 2b inside the multiplexer 1. Further, the input / output terminals 4a and 4b are connected to an RF signal processing circuit (RFIC: Radio Frequency Integrated Circuit, not shown) outside the multiplexer 1 via an amplifier circuit or the like (not shown).
  • RFIC Radio Frequency Integrated Circuit
  • the filter 2b is a second filter connected between the common terminal 3 and the input / output terminal 4b.
  • the filter 2b is an elastic wave filter using elastic waves (for example, a reception filter), and its pass band is, for example, LTE Band1Rx (2110-2170 MHz).
  • the pass band of the filter 2b overlaps at least a part of the band 0.75 to 0.8 times the pass band of the filter 2a.
  • the pass band of the filter 2b overlaps at least a part of the frequency band from 0.75 times the lower limit frequency of the pass band of the filter 2a to 0.8 times the upper limit frequency of the pass band of the filter 2a. ..
  • FIG. 2 is a circuit configuration diagram showing an example of the first filter (filter 2a) according to the embodiment.
  • the filter 2a has, for example, series arm resonators S1, S2, S3 and S4 connected in series to each other as the plurality of series arm resonators.
  • the series arm resonator S1 is a series arm resonator arranged on the path connecting the common terminal 3 and the input / output terminal 4a, and is connected to the common terminal 3 closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a.
  • This is an example of a first elastic wave resonator.
  • the first elastic wave resonator connected closest to the common terminal 3 means that no other resonator is connected on the signal path between the common terminal 3 and the common terminal 3.
  • the filter 2a is, as the plurality of parallel arm resonators, between the parallel arm resonators P1 connected between the node between the series arm resonators S1 and S2 and the ground, and between the series arm resonators S2 and S3.
  • Parallel arm resonator P2 connected between the node and ground
  • parallel arm resonator P3 connected between the node and ground between the series arm resonators S3 and S4, and series arm resonator S4.
  • the series arm resonator S4 is composed of a plurality of (here, two) split resonators in which one resonator is split.
  • IMD Intermodulation Distortion
  • At least the series arm resonator S1 is composed of an IDT electrode that excites an elastic wave whose main component is an SH wave such as a leaky wave.
  • each of the plurality of elastic wave resonators (series arm resonators S1, S2, S3 and S4 and parallel arm resonators P1, P2, P3 and P4) in the filter 2a is mainly composed of SH waves such as leaky waves. It is composed of IDT electrodes that excite elastic waves.
  • Each IDT electrode of the plurality of elastic wave resonators is formed on a substrate having a piezoelectric layer (a substrate having piezoelectricity), and the substrate is a piezoelectric layer in which an IDT electrode is formed on one main surface.
  • the bulk wave sound velocity propagating is faster than the elastic wave sound velocity propagating in the piezoelectric layer. It comprises a bass piezo film in which the propagating bulk wave sound velocity is slower than the elastic wave sound velocity. Since each elastic wave resonator constituting the filter 2a has such a laminated structure, Rayleigh wave ripple is generated in the filter 2a.
  • FIG. 3 is a plan view and a cross-sectional view schematically showing the electrode configuration of the elastic wave resonator 10 according to the embodiment.
  • FIG. 3 illustrates a planar schematic diagram and a schematic cross-sectional view showing the structure of the elastic wave resonator 10 as an example of the plurality of elastic wave resonators in the filter 2a.
  • the elastic wave resonator 10 shown in FIG. 3 is for explaining a typical structure of a plurality of elastic wave resonators in the filter 2a, and the number and length of the plurality of electrode fingers constituting the electrode are explained. Sas, etc. are not limited to this.
  • the elastic wave resonator 10 includes an IDT electrode 11 formed of a piezoelectric substrate 100, an electrode 110, and a protective layer 113, and composed of these components, and a reflector 12.
  • the surface acoustic wave resonator 10 according to the present embodiment is a surface acoustic wave (SAW: Surface Acoustic Wave) resonator composed of an IDT electrode 11, a reflector 12, and a piezoelectric substrate 100.
  • SAW Surface Acoustic Wave
  • the comb-shaped electrode 11B is composed of a plurality of electrode fingers 11b arranged so as to extend in a direction intersecting the elastic wave propagation direction, and a bus bar electrode 11c connecting one ends of the plurality of electrode fingers 11b to each other. There is.
  • the electrode 110 constituting the IDT electrode 11 and the reflector 12 has a laminated structure of the adhesion layer 111 and the main electrode layer 112.
  • the adhesion layer 111 is a layer for improving the adhesion between the piezoelectric substrate 100 and the main electrode layer 112, and for example, Ti is used as the material.
  • the film thickness of the adhesion layer 111 is, for example, 12 nm.
  • the main electrode layer 112 for example, Al containing 1% Cu is used as a material.
  • the film thickness of the main electrode layer 112 is, for example, 162 nm.
  • the piezoelectric substrate 100 is a substrate having a piezoelectric layer in which the IDT electrode 11 and the reflector 12 are arranged on the main surface.
  • the piezoelectric substrate 100 is a piezoelectric substrate having a laminated structure in which a high sound velocity support substrate, a low sound velocity film, and a piezoelectric film (piezoelectric body layer) are laminated in this order.
  • the piezoelectric membrane is made of, for example, a 42 ° Y-cut X-propagated LiTaO 3 piezoelectric single crystal or piezoelectric ceramic.
  • the LiTaO3 piezoelectric single crystal may have a cut angle of 30 ° to 60 °.
  • the SH wave can be used as the main mode.
  • the piezoelectric membrane has a thickness of, for example, 600 nm.
  • the hypersonic support substrate is a substrate that supports the hypersonic film, the piezoelectric film, and the IDT electrode.
  • the high sound velocity support substrate is further a substrate in which the sound velocity of the bulk wave in the high sound velocity support substrate is higher than that of the surface acoustic wave propagating through the piezoelectric film or the elastic wave of the boundary wave, and the elastic surface wave is made into the piezoelectric film and low. It is confined in the part where the sound velocity film is laminated, and functions so as not to leak below the high sound velocity support substrate.
  • the hypersonic support substrate is, for example, a silicon substrate, and the thickness is, for example, 200 ⁇ m.
  • the low sound velocity film is a film in which the sound velocity of the bulk wave in the low sound velocity film is lower than that of the bulk wave propagating in the piezoelectric film, and is arranged between the piezoelectric film and the high sound velocity support substrate. Due to this structure and the property that the energy is concentrated in the medium in which the surface acoustic wave is essentially low sound velocity, the leakage of the surface acoustic wave energy to the outside of the IDT electrode 11 is suppressed.
  • the bass sound film is, for example, a film containing silicon dioxide as a main component, and has a thickness of, for example, 670 nm. It should be noted that a bonding layer made of Ti, Ni, or the like may be included between the low sound velocity films.
  • the low sound velocity film may have a multilayer structure composed of a plurality of low sound velocity materials. According to this laminated structure, it is possible to significantly increase the Q value at the resonance frequency and the antiresonance frequency as compared with the structure in which the piezoelectric substrate 100 is used as a single layer. That is, since a surface acoustic wave resonator having a high Q value can be configured, it is possible to construct a filter having a small insertion loss by using the surface acoustic wave resonator.
  • the high sound velocity support substrate has a structure in which a support substrate and a high sound velocity film in which the sound velocity of the bulk wave propagating is higher than that of the elastic wave of the surface wave or the boundary wave propagating in the piezoelectric film are laminated.
  • the support substrate is made of a piezoelectric material such as sapphire, lithium tantalate, lithium niobate, crystal, alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mulite, steatite, forsterite and the like.
  • Dielectrics such as various ceramics and glass, semiconductors such as silicon and gallium nitride, and resin substrates can be used.
  • the treble velocity film includes various aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, DLC film or diamond, a medium containing the above material as a main component, a medium containing a mixture of the above materials as a main component, and the like. High sonic material can be used.
  • each layer exemplified in the laminated structure of the piezoelectric substrate 100 is an example, and is changed according to the characteristics to be emphasized among the required high frequency propagation characteristics, for example.
  • the reflector 12 is arranged adjacent to the IDT electrode 11 in the elastic wave propagation direction.
  • the reflector 12 is composed of a plurality of reflective electrode fingers 12a arranged so as to extend in a direction intersecting the elastic wave propagation direction, and a bus bar electrode 12c connecting one ends of the plurality of reflective electrode fingers 12a.
  • the center of the electrode finger (for example, the electrode finger 11a) closest to the reflector 12 among the plurality of electrode fingers 11a and 11b, and the IDT electrode 11 among the plurality of reflective electrode fingers 12a.
  • the distance from the center of the closest reflective electrode finger 12a is defined as the IDT-reflector gap (also called IRGAP).
  • the IDT wavelength (also referred to as ⁇ IDT) doubles the repeating pitch of the plurality of electrode fingers 11a and 11b repeated in the direction of elastic wave propagation, such as the electrode finger 11a, the electrode finger 11b, the electrode finger 11a, the electrode finger 11b, and so on. Call).
  • the IDT wavelength is a repeating pitch of the plurality of electrode fingers 11a, and attention is paid only to the plurality of electrode fingers 11b. If this is the case, it can be said that the pitch is repeated for the plurality of electrode fingers 11b. Further, twice the repeating pitch of the plurality of reflecting electrode fingers 12a is defined as the reflector wavelength (also referred to as ⁇ REF).
  • the repeating pitch of the plurality of electrode fingers 11a and 11b is the distance between the electrode finger on the most one end side and the electrode finger on the other end side of the plurality of electrode fingers 11a and 11b in the elastic wave propagation direction, and the plurality of electrodes. It can be obtained as a value divided by the number of fingers 11a and 11b-1.
  • the repeating pitch of the plurality of reflective electrode fingers 12a is a plurality of distances between the reflective electrode finger on the onemost end side and the reflective electrode finger on the other end side of the plurality of reflective electrode fingers 12a in the elastic wave propagation direction. It can be obtained as a value divided by the number of the reflecting electrode fingers 12a of the above-1 finger.
  • the pitches of the plurality of electrode fingers 11a and 11b do not have to be even pitches.
  • the pitch of each of the plurality of reflective electrode fingers 12a does not have to be a uniform pitch. That is, the repeating pitch does not necessarily have to be a constant pitch.
  • the logarithm of the plurality of electrode fingers 11a and 11b is the number of the paired electrode fingers 11a and the electrode fingers 11b, which is approximately half of the total number of the plurality of electrode fingers 11a and 11b.
  • the logarithm is N and the total number of the plurality of electrode fingers 11a and 11b is M
  • M (N + 1) ⁇ 2 is satisfied. That is, the number of regions sandwiched between the tip portion of one of the comb-shaped electrodes 11A and 11B and the other bus bar electrode facing the tip portion corresponds to 0.5 pair.
  • the frequency at which Rayleigh wave ripple is generated in the filter 2a is 0.76 times the frequency included in the pass band of the filter 2a, and is 0.75 to 0.8 times the frequency in consideration of the processing variation of the filter 2a. ..
  • the filter 2b which is commonly connected to the filter 2a and the common terminal 3, has a pass band including the frequency at which the Rayleigh wave ripple is generated in the filter 2a. Therefore, Rayleigh wave ripple occurs in the pass band (Band1Rx) of the filter 2b that overlaps with the frequency 0.75 to 0.8 times the frequency included in the pass band (Band7Rx) of the filter 2a.
  • the reflectance coefficient when the filter 2a is viewed from the common terminal 3 deteriorates (decreases), in other words, the return loss increases.
  • the return loss at the frequency at which the Rayleigh wave ripple occurs is also referred to as the return loss of the Rayleigh wave ripple.
  • the ripple caused by the Rayleigh wave ripple is generated in the pass band of the filter 2b.
  • the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 increases, and the insertion loss in the pass band of the filter 2b worsens accordingly.
  • the factor deteriorating the insertion loss of the filter 2b is the Rayleigh wave ripple described above, which is the closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a.
  • the series arm resonator S1 satisfies at least one of the following conditions (i), (ii) and (iii)
  • the return loss of the Rayleigh wave ripple can be reduced, and thus within the pass band of the filter 2b.
  • the series arm resonator S1 Since the series arm resonator S1 is connected closest to the common terminal 3 among the plurality of elastic wave resonators, the filter 2a and the filter 2b commonly connected at the common terminal 3 among the plurality of elastic wave resonators are the closest. It will be connected soon. This means that the series arm resonator S1 is an elastic wave resonator that most easily affects the filter 2b among the plurality of elastic wave resonators. Therefore, paying attention to the series arm resonator S1, the series arm resonator S1 satisfies at least one of the above (i), the above (ii), and the above (iii), so that the filter 2b can be used. Deterioration of insertion loss in the pass band can be effectively suppressed.
  • FIG. 4 is a graph showing the relationship between the logarithm and the return loss of the Rayleigh wave ripple.
  • ⁇ REF / ⁇ IDT also referred to as wavelength ratio
  • IRGAP is 0.5 times ⁇ REF. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (i) and (ii).
  • the filter 2a when the filter 2a is viewed from the common terminal 3 by satisfying at least the above condition (iii) in the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators.
  • the return loss of Rayleigh wave ripple can be reduced. Therefore, it is possible to suppress the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator.
  • FIG. 5 is a graph showing the relationship between the wavelength ratio and the return loss of Rayleigh wave ripple.
  • IRGAP is 0.5 times ⁇ REF
  • the logarithm of a plurality of electrode fingers is 80 pairs. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (ii) and (iii).
  • FIG. 6 is a graph showing the relationship between IRGAP and the return loss of Rayleigh wave ripple.
  • the wavelength ratio is 1.0
  • the logarithm of the plurality of electrode fingers is 80 pairs. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (i) and (iii).
  • IRGAP is gradually higher is the return loss of the Rayleigh wave ripple small large, is greater than 0.5 times the IRGAP is lambda REF, specifically, 0 IRGAP of lambda REF. It can be seen that the return loss of the Rayleigh wave ripple is 0.5 dB or less at 6 times (thick dotted line in FIG. 6). As a result, the deterioration of the insertion loss in the pass band of the filter 2b can be kept within about 0.15 dB.
  • the wavelength ratio of the series arm resonator S1 is 1.002
  • the IRGAP is 0.45 times that of ⁇ REF
  • the logarithm of the plurality of electrode fingers 11a and 11b is 150.5 pairs.
  • the child S1 does not satisfy any of the above conditions (i), (ii), and (iii).
  • FIG. 7 is a graph showing the passing characteristics of the first filter (filter 2a) according to the comparative example.
  • FIG. 8 is a graph showing the return loss characteristics seen from the common terminal 3 side of the first filter (filter 2a) according to the comparative example.
  • the filter is as shown by the circled portion of the broken line in FIG. It can be seen that Rayleigh wave ripple occurs in the pass band (Band1Rx) of the filter 2b which overlaps with the frequency of about 0.76 times the frequency included in the pass band (Band7Rx) of 2a. At the frequency at which this Rayleigh wave ripple occurs, the reflectance coefficient when the filter 2a is viewed from the common terminal 3 deteriorates (decreases), in other words, the return loss increases. As described above, it can be seen that the return loss of the Rayleigh wave ripple is large at about 1.7 dB.
  • the series arm resonator S1 has a wavelength ratio of 1.025, an IRGAP of 0.5 times that of ⁇ REF , and a logarithm of a plurality of electrode fingers 11a and 11b having 85 pairs. Satisfies the condition of (i) above.
  • FIG. 9 is a graph comparing the return loss characteristics seen from the common terminal 3 side of the first filter (filter 2a) according to the examples and the comparative examples.
  • FIG. 10 is a graph showing the gain characteristics of the amplifier circuit connected to the second filter (filter 2b) according to the examples and the comparative examples.
  • the series arm resonator S1 satisfies the condition (i) above, it is not shown, but the frequency is about 0.76 times the frequency included in the pass band (Band7Rx) of the filter 2a.
  • the Rayleigh wave ripple generated in the pass band (Band1Rx) of the filter 2b overlapping with the filter 2b becomes smaller. Therefore, as shown in FIG. 9, the return loss of the Rayleigh wave ripple, which is about 1.7 dB in the comparative example (broken line in FIG. 9), is about 0.6 dB in the embodiment (solid line in FIG. 9). It can be seen that there is a great improvement.
  • the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators satisfies any one of the above conditions (i), (ii), and (iii). It was shown that the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator can be suppressed, but the series arm resonator S1 has the above (i), the above (ii) and Further improvement can be achieved if two of the above two conditions (iii) or all of them are satisfied.
  • 11 and 12 are circuit configuration diagrams showing a modified example of the first filter (filter 2a) according to the embodiment.
  • the filter 2a may include a vertically coupled resonator M1.
  • the filter 2a shown in FIG. 11 includes series arm resonators S1 and S2 and a parallel arm resonator P1 in the same manner as the filter 2a shown in FIG. 2, and connects the series arm resonator S2 and the input / output terminal 4a.
  • a vertically coupled resonator M1 is arranged on the path.
  • at least one elastic wave resonator other than the first elastic wave resonator (here, the series arm resonator S1) among the plurality of elastic wave resonators included in the filter 2a constitutes the longitudinal coupling type resonator M1. ..
  • the longitudinally coupled resonator M1 is a 5-electrode type longitudinally coupled resonator provided with longitudinally coupled resonators N1, N2, N3, N4 and N5, and the at least one elastic wave resonator is a longitudinally coupled resonator. It becomes children N1, N2, N3, N4 and N5.
  • the first elastic wave resonator connected closest to the common terminal 3 is a path connecting the common terminal 3 and the input / output terminal 4a.
  • the series arm resonator S1 is arranged above, in the modified example shown in FIG. 12, the first elastic wave resonator connected closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a.
  • the multiplexer 1 includes a common terminal 3, input / output terminals 4a and 4b, a filter 2a connected between the common terminal 3 and the input / output terminal 4a, and a common terminal 3 and an input / output terminal 4b.
  • a filter 2b connected between the two.
  • the pass band of the filter 2b overlaps at least a part of the band 0.75 to 0.8 times the pass band of the filter 2a.
  • the filter 2a includes a plurality of elastic wave resonators, and the first elastic wave resonator connected closest to the common terminal 3 among the plurality of elastic wave resonators is formed on a substrate having a piezoelectric layer.
  • the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 can be reduced, and the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator can be suppressed. ..
  • the multiplexer 1 may satisfy at least two conditions of the above (i), the above (ii), and the above (iii). Further, for example, the multiplexer 1 may satisfy all the conditions of the above (i), the above (ii), and the above (iii).
  • the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 can be further reduced, and the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator is further reduced. Can be suppressed.
  • the first elastic wave resonator may be a series arm resonator S1 arranged on a path connecting the common terminal 3 and the input / output terminal 4a, as shown in FIG. 2 or FIG. As shown in FIG. 12, it may be a parallel arm resonator P1 connected between a node on the path connecting the common terminal 3 and the input / output terminal 4a and the ground.
  • the filter 2a may be a ladder type filter as shown in FIG.
  • At least one elastic wave resonator other than the first elastic wave resonator among the plurality of elastic wave resonators may constitute the longitudinal coupling type resonator M1.
  • the multiplexer 1 according to the embodiment of the present invention has been described above, the present invention relates to another embodiment realized by combining arbitrary components in the above embodiment and the above embodiment.
  • the present invention also includes modifications obtained by performing various modifications that can be conceived by those skilled in the art without departing from the gist of the present invention.
  • the multiplexer 1 can be applied to a communication device including a high frequency front end circuit and further a high frequency front end circuit.
  • the present invention also includes various devices incorporating a high-frequency front-end circuit to which the multiplexer 1 is applied and a communication device.
  • the number of the plurality of elastic wave resonators in the filter 2a according to the embodiment may be two.
  • the filter 2b according to the embodiment may not be an elastic wave filter, but may be an LC filter or the like.
  • the present invention can be widely used in communication devices such as mobile phones as a multiplexer applicable to a multi-band system.

Abstract

This multiplexer (1) is provided with a first filter and a second filter (2a and 2b) which share a common connection at a common terminal (3); the passband of the second filter (2b) overlaps, at least partially, with a band 0.75-0.8 times the passband of the first filter (2a); and among a plurality of elastic wave resonators provided in the first filter (2a), a first elastic wave resonator connected nearest to the common terminal (3) satisfies at least one of the conditions (i), (ii) and (iii) below. (i) The repeat pitch of the reflector / the repeat pitch of the IDT electrode ≥ 1.01. (ii) The distance between the IDT electrode and the reflector > the repeat pitch of the reflector. (iii) The number of pairs of the plurality of electrode fingers of the IDT electrode ≤ 50 pairs.

Description

マルチプレクサMultiplexer
　本発明は、マルチプレクサに関する。 The present invention relates to a multiplexer.
　近年、携帯電話端末等の通信装置について、１つの端末で複数の周波数帯域および複数の無線方式、いわゆるマルチバンドおよびマルチモードに対応するため、高周波信号を周波数帯域ごとに分離（分波）するマルチプレクサ（分波器）が広く用いられている。 In recent years, in communication devices such as mobile phone terminals, a multiplexer that separates (demultiplexes) high-frequency signals for each frequency band in order to support multiple frequency bands and multiple wireless systems, so-called multi-band and multi-mode, with one terminal. (Demultiplexer) is widely used.
　特許文献１には、このようなマルチプレクサとして、リーキー波をメインモードとする弾性波フィルタを含む複数のフィルタからなるマルチプレクサが開示されている。 Patent Document 1 discloses as such a multiplexer, a multiplexer composed of a plurality of filters including an elastic wave filter having a leaky wave as a main mode.
国際公開第２０１６／２０８６７０号International Publication No. 2016/208670
　しかしながら、リーキー波をメインモードとする弾性波フィルタにおける弾性波共振子では、メイン帯域に対して０．７５倍から０．８倍の周波数帯域に不要波（レイリー波）リップルが生じる。このような弾性波共振子を用いた弾性波フィルタを共通端子に接続したマルチプレクサにおいて、当該共通端子に共通接続された他のフィルタの通過帯域にレイリー波リップルの周波数が含まれる場合、当該他のフィルタの通過特性が劣化するという問題がある。 However, in the elastic wave resonator in the elastic wave filter whose main mode is the leaky wave, unnecessary wave (Rayleigh wave) ripple occurs in the frequency band 0.75 to 0.8 times the main band. In a multiplexer in which an elastic wave filter using such an elastic wave resonator is connected to a common terminal, if the pass band of another filter commonly connected to the common terminal includes the frequency of the Rayleigh wave ripple, the other There is a problem that the pass characteristics of the filter deteriorate.
　そこで、本発明は、弾性波共振子のレイリー波リップルによる通過帯域内の挿入損失の劣化を抑制できるマルチプレクサ等を提供することを目的とする。 Therefore, an object of the present invention is to provide a multiplexer or the like capable of suppressing deterioration of insertion loss in the pass band due to Rayleigh wave ripple of elastic wave resonators.
　本発明の一態様に係るマルチプレクサは、共通端子、第１入出力端子および第２入出力端子と、前記共通端子と前記第１入出力端子との間に接続される第１フィルタと、前記共通端子と前記第２入出力端子との間に接続される第２フィルタと、を備え、前記第２フィルタの通過帯域は、前記第１フィルタの通過帯域の０．７５倍から０．８倍の帯域と少なくとも一部が重なり、前記第１フィルタは、複数の弾性波共振子を備え、前記複数の弾性波共振子のうち前記共通端子に最も近く接続された第１弾性波共振子は、圧電体層を有する基板上に形成された、ＩＤＴ電極と、前記ＩＤＴ電極と弾性波伝搬方向に隣り合って配置された反射器と、を備え、前記ＩＤＴ電極は、前記弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の電極指で構成され、前記反射器は、前記弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の反射電極指で構成され、前記第１弾性波共振子は、以下の（ｉ）、（ｉｉ）および（ｉｉｉ）のうちの少なくとも１つの条件を満たす。（ｉ）前記複数の反射電極指の繰り返しピッチ／前記複数の電極指の繰り返しピッチ≧１．０１。（ｉｉ）前記複数の電極指のうち前記反射器に最近接する電極指の中心と前記複数の反射電極指のうち前記ＩＤＴ電極に最近接する反射電極指の中心との距離＞前記複数の反射電極指の繰り返しピッチ。（ｉｉｉ）前記複数の電極指の対数≦５０対。 The multiplexer according to one aspect of the present invention is common to the common terminal, the first input / output terminal and the second input / output terminal, and the first filter connected between the common terminal and the first input / output terminal. A second filter connected between the terminal and the second input / output terminal is provided, and the pass band of the second filter is 0.75 to 0.8 times the pass band of the first filter. The first filter has a plurality of elastic wave resonators that overlap at least a part of the band, and the first elastic wave resonator connected closest to the common terminal among the plurality of elastic wave resonators is piezoelectric. An IDT electrode formed on a substrate having a body layer and a reflector arranged adjacent to the IDT electrode in the elastic wave propagation direction are provided, and the IDT electrode intersects the elastic wave propagation direction. It is composed of a plurality of electrode fingers extending in a direction and arranged parallel to each other, and the reflector is composed of a plurality of reflecting electrode fingers extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other. The first elastic wave resonator satisfies at least one of the following conditions (i), (ii) and (iii). (I) Repeat pitch of the plurality of reflective electrode fingers / Repeat pitch of the plurality of electrode fingers ≧ 1.01. (Ii) Distance between the center of the electrode finger closest to the reflector among the plurality of electrode fingers and the center of the reflective electrode finger closest to the IDT electrode among the plurality of reflective electrode fingers> the plurality of reflective electrode fingers Repeated pitch. (Iii) The logarithm of the plurality of electrode fingers ≤ 50 pairs.
　本発明に係るマルチプレクサによれば、弾性波共振子のレイリー波リップルによる通過帯域内の挿入損失の劣化を抑制できる。 According to the multiplexer according to the present invention, it is possible to suppress the deterioration of the insertion loss in the pass band due to the Rayleigh wave ripple of the elastic wave resonator.
図１は、実施の形態に係るマルチプレクサの一例を示す構成図である。FIG. 1 is a configuration diagram showing an example of a multiplexer according to an embodiment. 図２は、実施の形態に係る第１フィルタの一例を示す回路構成図である。FIG. 2 is a circuit configuration diagram showing an example of the first filter according to the embodiment. 図３は、実施の形態に係る弾性波共振子の電極構成を模式的に表す平面図および断面図である。FIG. 3 is a plan view and a cross-sectional view schematically showing the electrode configuration of the elastic wave resonator according to the embodiment. 図４は、対数とレイリー波リップルのリターンロスとの関係を示すグラフである。FIG. 4 is a graph showing the relationship between the logarithm and the return loss of the Rayleigh wave ripple. 図５は、波長比とレイリー波リップルのリターンロスとの関係を示すグラフである。FIG. 5 is a graph showing the relationship between the wavelength ratio and the return loss of Rayleigh wave ripple. 図６は、ＩＲＧＡＰとレイリー波リップルのリターンロスとの関係を示すグラフである。FIG. 6 is a graph showing the relationship between IRGAP and the return loss of Rayleigh wave ripple. 図７は、比較例に係る第１フィルタの通過特性を示すグラフである。FIG. 7 is a graph showing the passing characteristics of the first filter according to the comparative example. 図８は、比較例に係る第１フィルタの共通端子側から見たリターンロス特性を示すグラフである。FIG. 8 is a graph showing the return loss characteristics seen from the common terminal side of the first filter according to the comparative example. 図９は、実施例および比較例に係る第１フィルタの共通端子側から見たリターンロス特性を比較したグラフである。FIG. 9 is a graph comparing the return loss characteristics seen from the common terminal side of the first filter according to the example and the comparative example. 図１０は、実施例および比較例に係る第２フィルタに接続された増幅回路のゲイン特性を示すグラフである。FIG. 10 is a graph showing the gain characteristics of the amplifier circuit connected to the second filter according to the example and the comparative example. 図１１は、実施の形態に係る第１フィルタの変形例を示す回路構成図である。FIG. 11 is a circuit configuration diagram showing a modified example of the first filter according to the embodiment. 図１２は、実施の形態に係る第１フィルタの変形例を示す回路構成図である。FIG. 12 is a circuit configuration diagram showing a modified example of the first filter according to the embodiment.
　以下、本発明の実施の形態について、図面を用いて詳細に説明する。なお、以下で説明する実施の形態は、いずれも包括的または具体的な例を示すものである。以下の実施の形態で示される数値、形状、材料、構成要素、構成要素の配置および接続形態などは、一例であり、本発明を限定する主旨ではない。以下の実施の形態における構成要素のうち、独立請求項に記載されていない構成要素については、任意の構成要素として説明される。また、図面に示される構成要素の大きさ、または大きさの比は、必ずしも厳密ではない。また、各図において、実質的に同一の構成に対しては同一の符号を付しており、重複する説明は省略または簡略化する場合がある。また、以下の実施の形態において、「接続される」とは、直接接続される場合だけでなく、他の素子等を介して電気的に接続される場合も含まれる。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that all of the embodiments described below are comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement of components, connection modes, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Among the components in the following embodiments, the components not described in the independent claims are described as arbitrary components. Also, the sizes of the components shown in the drawings, or the ratio of sizes, are not always exact. Further, in each figure, the same reference numerals are given to substantially the same configurations, and duplicate explanations may be omitted or simplified. Further, in the following embodiments, "connected" includes not only the case of being directly connected but also the case of being electrically connected via another element or the like.
　（実施の形態）
　［１．マルチプレクサの構成］
　図１は、実施の形態に係るマルチプレクサ１の一例を示す構成図である。図１には、マルチプレクサ１の共通端子３に接続されたアンテナ素子ＡＮＴも図示されている。アンテナ素子ＡＮＴは、例えばＬＴＥ（Ｌｏｎｇ　Ｔｅｒｍ　Ｅｖｏｌｕｔｉｏｎ）等の通信規格に準拠したマルチバンド対応のアンテナである。 (Embodiment)
[1. Multiplexer configuration]
FIG. 1 is a configuration diagram showing an example of a multiplexer 1 according to an embodiment. FIG. 1 also shows an antenna element ANT connected to the common terminal 3 of the multiplexer 1. The antenna element ANT is a multi-band compatible antenna conforming to a communication standard such as LTE (Long Term Evolution).
　マルチプレクサ１は、弾性波フィルタを用いた分波／合波回路である。マルチプレクサ１は、入出力端子として、共通端子３ならびに入出力端子４ａおよび４ｂを備える。入出力端子４ａは第１入出力端子の一例であり、入出力端子４ｂは第２入出力端子の一例である。マルチプレクサ１は、フィルタ２ａおよび２ｂを備え、それぞれの一方側（上記入出力端子４ａおよび４ｂ側とは異なる側）が共通端子３に共通接続されている。 The multiplexer 1 is a demultiplexing / combining circuit using an elastic wave filter. The multiplexer 1 includes a common terminal 3 and input / output terminals 4a and 4b as input / output terminals. The input / output terminal 4a is an example of a first input / output terminal, and the input / output terminal 4b is an example of a second input / output terminal. The multiplexer 1 includes filters 2a and 2b, and one side of each (a side different from the input / output terminals 4a and 4b side) is commonly connected to the common terminal 3.
　共通端子３は、フィルタ２ａおよび２ｂに共通に設けられ、マルチプレクサ１の内部でフィルタ２ａおよび２ｂに接続されている。また、共通端子３は、マルチプレクサ１の外部でアンテナ素子ＡＮＴに接続される。つまり、共通端子３は、マルチプレクサ１のアンテナ端子でもある。 The common terminal 3 is provided in common to the filters 2a and 2b, and is connected to the filters 2a and 2b inside the multiplexer 1. Further, the common terminal 3 is connected to the antenna element ANT outside the multiplexer 1. That is, the common terminal 3 is also the antenna terminal of the multiplexer 1.
　入出力端子４ａは、フィルタ２ａに対応して設けられ、マルチプレクサ１の内部でフィルタ２ａに接続されている。入出力端子４ｂは、フィルタ２ｂに対応して設けられ、マルチプレクサ１の内部でフィルタ２ｂに接続されている。また、入出力端子４ａおよび４ｂは、マルチプレクサ１の外部で、増幅回路等（図示せず）を介してＲＦ信号処理回路（ＲＦＩＣ：Ｒａｄｉｏ　Ｆｒｅｑｕｅｎｃｙ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ、図示せず）に接続される。 The input / output terminal 4a is provided corresponding to the filter 2a and is connected to the filter 2a inside the multiplexer 1. The input / output terminal 4b is provided corresponding to the filter 2b and is connected to the filter 2b inside the multiplexer 1. Further, the input / output terminals 4a and 4b are connected to an RF signal processing circuit (RFIC: Radio Frequency Integrated Circuit, not shown) outside the multiplexer 1 via an amplifier circuit or the like (not shown).
　フィルタ２ａは、共通端子３と入出力端子４ａとの間に接続される第１フィルタである。フィルタ２ａは、弾性波を用いた弾性波フィルタ（例えば受信フィルタ）であり、その通過帯域は、例えばＬＴＥのＢａｎｄ７Ｒｘ（２６２０－２６９０ＭＨｚ）である。 The filter 2a is a first filter connected between the common terminal 3 and the input / output terminal 4a. The filter 2a is an elastic wave filter using elastic waves (for example, a reception filter), and its pass band is, for example, LTE Band7Rx (2620-1690 MHz).
　フィルタ２ｂは、共通端子３と入出力端子４ｂとの間に接続される第２フィルタである。フィルタ２ｂは、弾性波を用いた弾性波フィルタ（例えば受信フィルタ）であり、その通過帯域は、例えばＬＴＥのＢａｎｄ１Ｒｘ（２１１０－２１７０ＭＨｚ）である。フィルタ２ｂの通過帯域は、フィルタ２ａの通過帯域の０．７５倍から０．８倍の帯域と少なくとも一部が重なる。具体的には、フィルタ２ｂの通過帯域は、フィルタ２ａの通過帯域の下限周波数の０．７５倍から、フィルタ２ａの通過帯域の上限周波数の０．８倍までの周波数帯域と少なくとも一部が重なる。なお、フィルタ２ａおよび２ｂの通過帯域は、フィルタ２ｂの通過帯域がフィルタ２ａの通過帯域の０．７５倍から０．８倍の帯域と少なくとも一部が重なるのであれば、Ｂａｎｄ７ＲｘおよびＢａｎｄ１Ｒｘの組み合わせに限らない。なお、通過帯域は、設計値に基づく（理論またはシミュレーション）計算によって、あるいは実際の製品に対する評価試験によって、あるいは実際の製品の仕様書等に基づいて、特定されうる。 The filter 2b is a second filter connected between the common terminal 3 and the input / output terminal 4b. The filter 2b is an elastic wave filter using elastic waves (for example, a reception filter), and its pass band is, for example, LTE Band1Rx (2110-2170 MHz). The pass band of the filter 2b overlaps at least a part of the band 0.75 to 0.8 times the pass band of the filter 2a. Specifically, the pass band of the filter 2b overlaps at least a part of the frequency band from 0.75 times the lower limit frequency of the pass band of the filter 2a to 0.8 times the upper limit frequency of the pass band of the filter 2a. .. The pass band of the filters 2a and 2b is a combination of Band 7Rx and Band 1Rx if the pass band of the filter 2b partially overlaps with the band of 0.75 to 0.8 times the pass band of the filter 2a. Not exclusively. The passband can be specified by a calculation based on a design value (theoretical or simulation), an evaluation test on an actual product, or a specification of an actual product.
　なお、マルチプレクサ１において共通端子３に接続されるフィルタの数は、３つ以上であってもよい。また、マルチプレクサ１には、送信フィルタおよび受信フィルタの両方が含まれていてもよいし、マルチプレクサ１は、複数の送信フィルタのみ、または、複数の受信フィルタのみで構成されていてもよい。 The number of filters connected to the common terminal 3 in the multiplexer 1 may be three or more. Further, the multiplexer 1 may include both a transmission filter and a reception filter, and the multiplexer 1 may be composed of only a plurality of transmission filters or only a plurality of reception filters.
　［２．フィルタの構成］
　次に、実施の形態に係るフィルタ２ａの構成について説明する。 [2. Filter configuration]
Next, the configuration of the filter 2a according to the embodiment will be described.
　図２は、実施の形態に係る第１フィルタ（フィルタ２ａ）の一例を示す回路構成図である。 FIG. 2 is a circuit configuration diagram showing an example of the first filter (filter 2a) according to the embodiment.
　フィルタ２ａは、複数の弾性波共振子を備える。フィルタ２ａは、複数の弾性波共振子として、例えば、共通端子３と入出力端子４ａとを結ぶ経路上に配置された複数の直列腕共振子と、当該経路上に設けられたノードとグランドとの間に配置された複数の並列腕共振子とを備える。ノードとは、素子と素子、または、素子と端子の間の接続点である。フィルタ２ａは、例えばラダー型のフィルタである。なお、フィルタ２ａにおける複数の弾性波共振子の数および配置等は図２に示されるものに限らない。 The filter 2a includes a plurality of elastic wave resonators. The filter 2a includes, as a plurality of elastic wave resonators, for example, a plurality of series arm resonators arranged on a path connecting the common terminal 3 and the input / output terminal 4a, and a node and ground provided on the path. It is equipped with a plurality of parallel arm resonators arranged between the two. A node is a connection point between an element and an element or an element and a terminal. The filter 2a is, for example, a ladder type filter. The number and arrangement of the plurality of elastic wave resonators in the filter 2a are not limited to those shown in FIG.
　フィルタ２ａは、上記複数の直列腕共振子として、例えば、互いに直列接続された直列腕共振子Ｓ１、Ｓ２、Ｓ３およびＳ４を有する。直列腕共振子Ｓ１は、共通端子３と入出力端子４ａとを結ぶ経路上に配置された直列腕共振子であり、フィルタ２ａにおける複数の弾性波共振子のうち共通端子３に最も近く接続された第１弾性波共振子の一例である。なお、共通端子３に最も近く接続された第１弾性波共振子とは、共通端子３との間の信号経路上に他の共振子が接続されていないことを意味する。なお、共通端子３と第１弾性波共振子との間の信号経路上に共振子以外の素子（例えばインダクタ等）が接続されていてもよい。また、フィルタ２ａは、上記複数の並列腕共振子として、直列腕共振子Ｓ１およびＳ２の間のノードとグランドとの間に接続された並列腕共振子Ｐ１、直列腕共振子Ｓ２およびＳ３の間のノードとグランドとの間に接続された並列腕共振子Ｐ２、直列腕共振子Ｓ３およびＳ４の間のノードとグランドとの間に接続された並列腕共振子Ｐ３、ならびに、直列腕共振子Ｓ４および入出力端子４ａの間のノードとグランドとの間に接続された並列腕共振子Ｐ４を有する。 The filter 2a has, for example, series arm resonators S1, S2, S3 and S4 connected in series to each other as the plurality of series arm resonators. The series arm resonator S1 is a series arm resonator arranged on the path connecting the common terminal 3 and the input / output terminal 4a, and is connected to the common terminal 3 closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a. This is an example of a first elastic wave resonator. The first elastic wave resonator connected closest to the common terminal 3 means that no other resonator is connected on the signal path between the common terminal 3 and the common terminal 3. An element other than the resonator (for example, an inductor) may be connected on the signal path between the common terminal 3 and the first elastic wave resonator. Further, the filter 2a is, as the plurality of parallel arm resonators, between the parallel arm resonators P1 connected between the node between the series arm resonators S1 and S2 and the ground, and between the series arm resonators S2 and S3. Parallel arm resonator P2 connected between the node and ground, parallel arm resonator P3 connected between the node and ground between the series arm resonators S3 and S4, and series arm resonator S4. And has a parallel arm resonator P4 connected between the node between the input / output terminals 4a and the ground.
　直列腕共振子Ｓ１、Ｓ２、Ｓ３およびＳ４ならびに並列腕共振子Ｐ１、Ｐ２、Ｐ３およびＰ４は、フィルタ２ａの通過帯域を構成する共振子である。具体的には、直列腕共振子Ｓ１、Ｓ２、Ｓ３およびＳ４の共振周波数および並列腕共振子Ｐ１、Ｐ２、Ｐ３およびＰ４の反共振周波数がフィルタ２ａの通過帯域の中心周波数付近に位置するように設計される。また、直列腕共振子Ｓ１、Ｓ２、Ｓ３およびＳ４の反共振周波数が当該通過帯域の高域側近傍の減衰極に、並列腕共振子Ｐ１、Ｐ２、Ｐ３およびＰ４の共振周波数が当該通過帯域の低域側近傍の減衰極に位置するように設計される。このようにして、フィルタ２ａの通過帯域は形成される。 The series arm resonators S1, S2, S3 and S4 and the parallel arm resonators P1, P2, P3 and P4 are resonators constituting the pass band of the filter 2a. Specifically, the resonance frequencies of the series arm resonators S1, S2, S3 and S4 and the antiresonance frequencies of the parallel arm resonators P1, P2, P3 and P4 are located near the center frequency of the pass band of the filter 2a. Designed. Further, the antiresonance frequencies of the series arm resonators S1, S2, S3 and S4 are in the attenuation pole near the high frequency side of the pass band, and the resonance frequencies of the parallel arm resonators P1, P2, P3 and P4 are in the pass band. It is designed to be located at the attenuation pole near the low frequency side. In this way, the pass band of the filter 2a is formed.
　また、図２に示されるフィルタ２ａでは、直列腕共振子Ｓ４は、１つの共振子が分割された複数の（ここでは２つの）分割共振子によって構成されている。詳細な説明は省略するが、１つの共振子が複数の分割共振子によって構成されることで、ＩＭＤ（Ｉｎｔｅｒ　Ｍｏｄｕｌａｔｉｏｎ　Ｄｉｓｔｏｒｔｉｏｎ）特性を改善することができる。 Further, in the filter 2a shown in FIG. 2, the series arm resonator S4 is composed of a plurality of (here, two) split resonators in which one resonator is split. Although detailed description is omitted, the IMD (Intermodulation Distortion) characteristics can be improved by configuring one resonator with a plurality of divided resonators.
　少なくとも直列腕共振子Ｓ１は、リーキー波などのＳＨ波を主成分とする弾性波を励振するＩＤＴ電極によって構成される。ここでは、フィルタ２ａにおける複数の弾性波共振子（直列腕共振子Ｓ１、Ｓ２、Ｓ３およびＳ４ならびに並列腕共振子Ｐ１、Ｐ２、Ｐ３およびＰ４）のそれぞれが、リーキー波などのＳＨ波を主成分とする弾性波を励振するＩＤＴ電極によって構成される。 At least the series arm resonator S1 is composed of an IDT electrode that excites an elastic wave whose main component is an SH wave such as a leaky wave. Here, each of the plurality of elastic wave resonators (series arm resonators S1, S2, S3 and S4 and parallel arm resonators P1, P2, P3 and P4) in the filter 2a is mainly composed of SH waves such as leaky waves. It is composed of IDT electrodes that excite elastic waves.
　複数の弾性波共振子のそれぞれのＩＤＴ電極は、圧電体層を有する基板（圧電性を有する基板）上に形成され、当該基板は、ＩＤＴ電極が一方の主面上に形成された圧電体層と、圧電体層を伝搬する弾性波音速よりも、伝搬するバルク波音速が高速である高音速支持基板と、高音速支持基板と圧電体層との間に配置され、圧電体層を伝搬する弾性波音速よりも、伝搬するバルク波音速が低速である低音速膜と、を備える。フィルタ２ａを構成する各弾性波共振子がこのような積層構造を有することで、フィルタ２ａにおいてレイリー波リップルが発生する。 Each IDT electrode of the plurality of elastic wave resonators is formed on a substrate having a piezoelectric layer (a substrate having piezoelectricity), and the substrate is a piezoelectric layer in which an IDT electrode is formed on one main surface. The bulk wave sound velocity propagating is faster than the elastic wave sound velocity propagating in the piezoelectric layer. It comprises a bass piezo film in which the propagating bulk wave sound velocity is slower than the elastic wave sound velocity. Since each elastic wave resonator constituting the filter 2a has such a laminated structure, Rayleigh wave ripple is generated in the filter 2a.
　［３．弾性波共振子の基本構造］
　次に、フィルタ２ａを構成する各弾性波共振子の基本構造について説明する。 [3. Basic structure of elastic wave resonator]
Next, the basic structure of each elastic wave resonator constituting the filter 2a will be described.
　図３は、実施の形態に係る弾性波共振子１０の電極構成を模式的に表す平面図および断面図である。図３には、フィルタ２ａにおける複数の弾性波共振子として、弾性波共振子１０を一例にその構造を表す平面摸式図および断面模式図が例示されている。なお、図３に示される弾性波共振子１０は、フィルタ２ａにおける複数の弾性波共振子の典型的な構造を説明するためのものであって、電極を構成する複数の電極指の本数や長さなどは、これに限定されない。 FIG. 3 is a plan view and a cross-sectional view schematically showing the electrode configuration of the elastic wave resonator 10 according to the embodiment. FIG. 3 illustrates a planar schematic diagram and a schematic cross-sectional view showing the structure of the elastic wave resonator 10 as an example of the plurality of elastic wave resonators in the filter 2a. The elastic wave resonator 10 shown in FIG. 3 is for explaining a typical structure of a plurality of elastic wave resonators in the filter 2a, and the number and length of the plurality of electrode fingers constituting the electrode are explained. Sas, etc. are not limited to this.
　弾性波共振子１０は、圧電基板１００と、電極１１０と、保護層１１３とで形成され、これらの構成要素で構成されたＩＤＴ電極１１と、反射器１２と、を備える。本実施の形態に係る弾性波共振子１０は、ＩＤＴ電極１１、反射器１２、および圧電基板１００で構成された弾性表面波（ＳＡＷ：Ｓｕｒｆａｃｅ　Ａｃｏｕｓｔｉｃ　Ｗａｖｅ）共振子である。 The elastic wave resonator 10 includes an IDT electrode 11 formed of a piezoelectric substrate 100, an electrode 110, and a protective layer 113, and composed of these components, and a reflector 12. The surface acoustic wave resonator 10 according to the present embodiment is a surface acoustic wave (SAW: Surface Acoustic Wave) resonator composed of an IDT electrode 11, a reflector 12, and a piezoelectric substrate 100.
　図３の平面図に示されるように、ＩＤＴ電極１１は、弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の電極指で構成される。ＩＤＴ電極１１は、互いに対向する一対の櫛歯状電極１１Ａおよび１１Ｂを有している。櫛歯状電極１１Ａは、弾性波伝搬方向と交差する方向に延びるように配置された複数の電極指１１ａと、複数の電極指１１ａのそれぞれの一端同士を接続するバスバー電極１１ｃとで構成されている。櫛歯状電極１１Ｂは、弾性波伝搬方向と交差する方向に延びるように配置された複数の電極指１１ｂと、複数の電極指１１ｂのそれぞれの一端同士を接続するバスバー電極１１ｃとで構成されている。 As shown in the plan view of FIG. 3, the IDT electrode 11 is composed of a plurality of electrode fingers extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other. The IDT electrode 11 has a pair of comb-shaped electrodes 11A and 11B facing each other. The comb-shaped electrode 11A is composed of a plurality of electrode fingers 11a arranged so as to extend in a direction intersecting the elastic wave propagation direction, and a bus bar electrode 11c connecting one ends of the plurality of electrode fingers 11a to each other. There is. The comb-shaped electrode 11B is composed of a plurality of electrode fingers 11b arranged so as to extend in a direction intersecting the elastic wave propagation direction, and a bus bar electrode 11c connecting one ends of the plurality of electrode fingers 11b to each other. There is.
　ＩＤＴ電極１１および反射器１２を構成する電極１１０は、図３の断面図に示すように、密着層１１１と主電極層１１２との積層構造となっている。 As shown in the cross-sectional view of FIG. 3, the electrode 110 constituting the IDT electrode 11 and the reflector 12 has a laminated structure of the adhesion layer 111 and the main electrode layer 112.
　密着層１１１は、圧電基板１００と主電極層１１２との密着性を向上させるための層であり、材料として、例えばＴｉが用いられる。密着層１１１の膜厚は、例えば１２ｎｍである。 The adhesion layer 111 is a layer for improving the adhesion between the piezoelectric substrate 100 and the main electrode layer 112, and for example, Ti is used as the material. The film thickness of the adhesion layer 111 is, for example, 12 nm.
　主電極層１１２は、材料として、例えばＣｕを１％含有したＡｌが用いられる。主電極層１１２の膜厚は、例えば１６２ｎｍである。 For the main electrode layer 112, for example, Al containing 1% Cu is used as a material. The film thickness of the main electrode layer 112 is, for example, 162 nm.
　保護層１１３は、電極１１０を覆うように形成されている。保護層１１３は、主電極層１１２を外部環境から保護すること、周波数温度特性を調整すること、および、耐湿性を高めることなどを目的とする層であり、例えば二酸化ケイ素（ＳｉＯ２）を主成分とする膜である。保護層１１３の膜厚は、例えば２５ｎｍである。 The protective layer 113 is formed so as to cover the electrode 110. The protective layer 113 is a layer for the purpose of protecting the main electrode layer 112 from the external environment, adjusting the frequency temperature characteristics, and improving the moisture resistance, and is mainly composed of , for example, silicon dioxide (SiO 2). It is a film as a component. The film thickness of the protective layer 113 is, for example, 25 nm.
　なお、密着層１１１、主電極層１１２および保護層１１３を構成する材料は、上述した材料に限定されない。さらに、電極１１０は、上記積層構造でなくてもよい。電極１１０は、例えば、Ｔｉ、Ａｌ、Ｃｕ、Ｐｔ、Ａｕ、Ａｇ、Ｐｄなどの金属または合金から構成されてもよく、また、上記の金属または合金から構成される複数の積層体から構成されてもよい。また、保護層１１３は、形成されていなくてもよい。 The materials constituting the adhesion layer 111, the main electrode layer 112, and the protective layer 113 are not limited to the above-mentioned materials. Further, the electrode 110 does not have to have the above-mentioned laminated structure. The electrode 110 may be made of, for example, a metal or alloy such as Ti, Al, Cu, Pt, Au, Ag, Pd, or may be made of a plurality of laminates made of the above metal or alloy. May be good. Further, the protective layer 113 may not be formed.
　圧電基板１００は、ＩＤＴ電極１１および反射器１２が主面上に配置された圧電体層を有する基板である。具体的には、圧電基板１００は、高音速支持基板と、低音速膜と、圧電膜（圧電体層）とがこの順で積層された積層構造を有する圧電性基板である。圧電膜は、例えば、４２°ＹカットＸ伝搬ＬｉＴａＯ３圧電単結晶または圧電セラミックスからなる。ＬｉＴａＯ３圧電単結晶は、カット角は３０°～６０°であればよい。このとき、ＳＨ波をメインモードとして利用することができる。圧電膜は、厚みが例えば６００ｎｍである。高音速支持基板は、低音速膜、圧電膜およびＩＤＴ電極を支持する基板である。高音速支持基板は、さらに、圧電膜を伝搬する表面波または境界波の弾性波よりも、高音速支持基板中のバルク波の音速が高速となる基板であり、弾性表面波を圧電膜および低音速膜が積層されている部分に閉じ込め、高音速支持基板より下方に漏れないように機能する。高音速支持基板は、例えば、シリコン基板であり、厚みは、例えば２００μｍである。低音速膜は、圧電膜を伝搬するバルク波よりも、低音速膜中のバルク波の音速が低速となる膜であり、圧電膜と高音速支持基板との間に配置される。この構造と、弾性波が本質的に低音速な媒質にエネルギーが集中するという性質とにより、弾性表面波エネルギーのＩＤＴ電極１１外への漏れが抑制される。低音速膜は、例えば二酸化ケイ素を主成分とする膜であり、厚みは、例えば６７０ｎｍである。なお、低音速膜の間に、ＴｉまたはＮｉなどからなる接合層を含んでいてもよい。低音速膜は複数の低音速材料からなる多層構造であってもよい。この積層構造によれば、圧電基板１００を単層で使用している構造と比較して、共振周波数および反共振周波数におけるＱ値を大幅に高めることが可能となる。すなわち、Ｑ値が高い弾性表面波共振子を構成し得るので、当該弾性表面波共振子を用いて、挿入損失が小さいフィルタを構成することが可能となる。 The piezoelectric substrate 100 is a substrate having a piezoelectric layer in which the IDT electrode 11 and the reflector 12 are arranged on the main surface. Specifically, the piezoelectric substrate 100 is a piezoelectric substrate having a laminated structure in which a high sound velocity support substrate, a low sound velocity film, and a piezoelectric film (piezoelectric body layer) are laminated in this order. The piezoelectric membrane is made of, for example, a 42 ° Y-cut X-propagated LiTaO 3 piezoelectric single crystal or piezoelectric ceramic. The LiTaO3 piezoelectric single crystal may have a cut angle of 30 ° to 60 °. At this time, the SH wave can be used as the main mode. The piezoelectric membrane has a thickness of, for example, 600 nm. The hypersonic support substrate is a substrate that supports the hypersonic film, the piezoelectric film, and the IDT electrode. The high sound velocity support substrate is further a substrate in which the sound velocity of the bulk wave in the high sound velocity support substrate is higher than that of the surface acoustic wave propagating through the piezoelectric film or the elastic wave of the boundary wave, and the elastic surface wave is made into the piezoelectric film and low. It is confined in the part where the sound velocity film is laminated, and functions so as not to leak below the high sound velocity support substrate. The hypersonic support substrate is, for example, a silicon substrate, and the thickness is, for example, 200 μm. The low sound velocity film is a film in which the sound velocity of the bulk wave in the low sound velocity film is lower than that of the bulk wave propagating in the piezoelectric film, and is arranged between the piezoelectric film and the high sound velocity support substrate. Due to this structure and the property that the energy is concentrated in the medium in which the surface acoustic wave is essentially low sound velocity, the leakage of the surface acoustic wave energy to the outside of the IDT electrode 11 is suppressed. The bass sound film is, for example, a film containing silicon dioxide as a main component, and has a thickness of, for example, 670 nm. It should be noted that a bonding layer made of Ti, Ni, or the like may be included between the low sound velocity films. The low sound velocity film may have a multilayer structure composed of a plurality of low sound velocity materials. According to this laminated structure, it is possible to significantly increase the Q value at the resonance frequency and the antiresonance frequency as compared with the structure in which the piezoelectric substrate 100 is used as a single layer. That is, since a surface acoustic wave resonator having a high Q value can be configured, it is possible to construct a filter having a small insertion loss by using the surface acoustic wave resonator.
　なお、高音速支持基板は、支持基板と、圧電膜を伝搬する表面波や境界波の弾性波よりも、伝搬するバルク波の音速が高速となる高音速膜とが積層された構造を有していてもよい。この場合、支持基板は、サファイア、リチウムタンタレート、リチュウムニオベイト、水晶等の圧電体、アルミナ、マグネシア、窒化ケイ素、窒化アルミニウム、炭化ケイ素、ジルコニア、コージライト、ムライト、ステアタイト、フォルステライト等の各種セラミック、ガラス等の誘電体またはシリコン、窒化ガリウム等の半導体および樹脂基板等を用いることができる。また、高音速膜は、窒化アルミニウム、酸化アルミニウム、炭化ケイ素、窒化ケイ素、酸窒化ケイ素、ＤＬＣ膜またはダイヤモンド、上記材料を主成分とする媒質、上記材料の混合物を主成分とする媒質等、様々な高音速材料を用いることができる。 The high sound velocity support substrate has a structure in which a support substrate and a high sound velocity film in which the sound velocity of the bulk wave propagating is higher than that of the elastic wave of the surface wave or the boundary wave propagating in the piezoelectric film are laminated. May be. In this case, the support substrate is made of a piezoelectric material such as sapphire, lithium tantalate, lithium niobate, crystal, alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mulite, steatite, forsterite and the like. Dielectrics such as various ceramics and glass, semiconductors such as silicon and gallium nitride, and resin substrates can be used. Further, the treble velocity film includes various aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, DLC film or diamond, a medium containing the above material as a main component, a medium containing a mixture of the above materials as a main component, and the like. High sonic material can be used.
　なお、圧電基板１００の上記積層構造において例示した各層の材料などは一例であり、例えば、要求される高周波伝搬特性のうち重視すべき特性に応じて変更されるものである。 The material of each layer exemplified in the laminated structure of the piezoelectric substrate 100 is an example, and is changed according to the characteristics to be emphasized among the required high frequency propagation characteristics, for example.
　反射器１２は、ＩＤＴ電極１１と弾性波伝搬方向に隣り合って配置されている。反射器１２は、弾性波伝搬方向と交差する方向に延びるように配置された複数の反射電極指１２ａと、複数の反射電極指１２ａの一端同士を接続するバスバー電極１２ｃとで構成されている。 The reflector 12 is arranged adjacent to the IDT electrode 11 in the elastic wave propagation direction. The reflector 12 is composed of a plurality of reflective electrode fingers 12a arranged so as to extend in a direction intersecting the elastic wave propagation direction, and a bus bar electrode 12c connecting one ends of the plurality of reflective electrode fingers 12a.
　ここで、図３に示されるように、複数の電極指１１ａおよび１１ｂのうち反射器１２に最近接する電極指（例えば電極指１１ａ）の中心と、複数の反射電極指１２ａのうちＩＤＴ電極１１に最近接する反射電極指１２ａの中心との距離を、ＩＤＴ－反射器ギャップ（ＩＲＧＡＰとも呼ぶ）と定義する。また、弾性波伝搬方向へ電極指１１ａ、電極指１１ｂ、電極指１１ａ、電極指１１ｂ、・・・と繰り返される複数の電極指１１ａおよび１１ｂの繰り返しピッチの２倍を、ＩＤＴ波長（λＩＤＴとも呼ぶ）と定義する。なお、ＩＤＴ波長は、複数の電極指１１ａおよび１１ｂのうちの複数の電極指１１ａのみに着目した場合には、複数の電極指１１ａの繰り返しピッチであるとも言え、複数の電極指１１ｂのみに着目した場合には、複数の電極指１１ｂの繰り返しピッチであるとも言える。また、複数の反射電極指１２ａの繰り返しピッチの２倍を、反射器波長（λＲＥＦとも呼ぶ）と定義する。 Here, as shown in FIG. 3, the center of the electrode finger (for example, the electrode finger 11a) closest to the reflector 12 among the plurality of electrode fingers 11a and 11b, and the IDT electrode 11 among the plurality of reflective electrode fingers 12a. The distance from the center of the closest reflective electrode finger 12a is defined as the IDT-reflector gap (also called IRGAP). Further, the IDT wavelength (also referred to as λ IDT) doubles the repeating pitch of the plurality of electrode fingers 11a and 11b repeated in the direction of elastic wave propagation, such as the electrode finger 11a, the electrode finger 11b, the electrode finger 11a, the electrode finger 11b, and so on. Call). When focusing only on a plurality of electrode fingers 11a among the plurality of electrode fingers 11a and 11b, it can be said that the IDT wavelength is a repeating pitch of the plurality of electrode fingers 11a, and attention is paid only to the plurality of electrode fingers 11b. If this is the case, it can be said that the pitch is repeated for the plurality of electrode fingers 11b. Further, twice the repeating pitch of the plurality of reflecting electrode fingers 12a is defined as the reflector wavelength (also referred to as λ REF).
　なお、複数の電極指１１ａおよび１１ｂの繰り返しピッチは、弾性波伝搬方向における、複数の電極指１１ａおよび１１ｂの最も一方端側の電極指と他方端側の電極指との距離を、複数の電極指１１ａおよび１１ｂの本数－１本で除した値として求めることができる。同じように、複数の反射電極指１２ａの繰り返しピッチは、弾性波伝搬方向における、複数の反射電極指１２ａの最も一方端側の反射電極指と他方端側の反射電極指との距離を、複数の反射電極指１２ａの本数－１本で除した値として求めることができる。 The repeating pitch of the plurality of electrode fingers 11a and 11b is the distance between the electrode finger on the most one end side and the electrode finger on the other end side of the plurality of electrode fingers 11a and 11b in the elastic wave propagation direction, and the plurality of electrodes. It can be obtained as a value divided by the number of fingers 11a and 11b-1. Similarly, the repeating pitch of the plurality of reflective electrode fingers 12a is a plurality of distances between the reflective electrode finger on the onemost end side and the reflective electrode finger on the other end side of the plurality of reflective electrode fingers 12a in the elastic wave propagation direction. It can be obtained as a value divided by the number of the reflecting electrode fingers 12a of the above-1 finger.
　また、複数の電極指１１ａおよび１１ｂの各々のピッチは、均等のピッチでなくてもよい。同じように、複数の反射電極指１２ａの各々のピッチは、均等のピッチでなくてもよい。すなわち、繰り返しピッチは、必ずしも一定のピッチが繰り返されなくてもよい。 Further, the pitches of the plurality of electrode fingers 11a and 11b do not have to be even pitches. Similarly, the pitch of each of the plurality of reflective electrode fingers 12a does not have to be a uniform pitch. That is, the repeating pitch does not necessarily have to be a constant pitch.
　また、複数の電極指１１ａおよび１１ｂの対数とは、対をなす電極指１１ａおよび電極指１１ｂの数であり、複数の電極指１１ａおよび１１ｂの総数の概ね半数である。例えば、対数をＮとし、複数の電極指１１ａおよび１１ｂの総数をＭとすると、Ｍ＝（Ｎ＋１）×２を満たす。すなわち、櫛歯状電極１１Ａおよび１１Ｂの一方の１つの電極指の先端部分と当該先端部分に対向する他方のバスバー電極とで挟まれる領域の数が０．５対に相当する。 Further, the logarithm of the plurality of electrode fingers 11a and 11b is the number of the paired electrode fingers 11a and the electrode fingers 11b, which is approximately half of the total number of the plurality of electrode fingers 11a and 11b. For example, assuming that the logarithm is N and the total number of the plurality of electrode fingers 11a and 11b is M, M = (N + 1) × 2 is satisfied. That is, the number of regions sandwiched between the tip portion of one of the comb-shaped electrodes 11A and 11B and the other bus bar electrode facing the tip portion corresponds to 0.5 pair.
　［４．レイリー波リップルの影響］
　ここで、フィルタ２ａに発生するレイリー波リップルの影響について説明する。フィルタ２ａにおけるレイリー波リップルの発生周波数は、フィルタ２ａの通過帯域に含まれる周波数の０．７６倍の周波数となり、フィルタ２ａの加工ばらつきを考慮すると０．７５倍から０．８倍の周波数となる。フィルタ２ａと共通端子３に共通接続されたフィルタ２ｂは、フィルタ２ａにおけるレイリー波リップルの発生周波数を含む通過帯域を有する。このため、フィルタ２ａの通過帯域（Ｂａｎｄ７Ｒｘ）に含まれる周波数の０．７５倍から０．８倍の周波数と重複するフィルタ２ｂの通過帯域（Ｂａｎｄ１Ｒｘ）においてレイリー波リップルが発生する。このレイリー波リップルが発生した周波数では、共通端子３からフィルタ２ａを見た場合の反射係数が悪化（低下）、言い換えると、リターンロスが増加する。レイリー波リップルが発生した周波数でのリターンロスを、以下レイリー波リップルのリターンロスともいう。マルチプレクサ１では、レイリー波リップルが発生した周波数がフィルタ２ｂの通過帯域に含まれるため、フィルタ２ｂの通過帯域内にレイリー波リップルに起因したリップルが発生する。このように、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスが増加し、これに伴いフィルタ２ｂの通過帯域内の挿入損失が悪化する。 [4. Effect of Rayleigh Wave Ripple]
Here, the influence of the Rayleigh wave ripple generated on the filter 2a will be described. The frequency at which Rayleigh wave ripple is generated in the filter 2a is 0.76 times the frequency included in the pass band of the filter 2a, and is 0.75 to 0.8 times the frequency in consideration of the processing variation of the filter 2a. .. The filter 2b, which is commonly connected to the filter 2a and the common terminal 3, has a pass band including the frequency at which the Rayleigh wave ripple is generated in the filter 2a. Therefore, Rayleigh wave ripple occurs in the pass band (Band1Rx) of the filter 2b that overlaps with the frequency 0.75 to 0.8 times the frequency included in the pass band (Band7Rx) of the filter 2a. At the frequency at which the Rayleigh wave ripple occurs, the reflectance coefficient when the filter 2a is viewed from the common terminal 3 deteriorates (decreases), in other words, the return loss increases. The return loss at the frequency at which the Rayleigh wave ripple occurs is also referred to as the return loss of the Rayleigh wave ripple. In the multiplexer 1, since the frequency in which the Rayleigh wave ripple is generated is included in the pass band of the filter 2b, the ripple caused by the Rayleigh wave ripple is generated in the pass band of the filter 2b. As described above, the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 increases, and the insertion loss in the pass band of the filter 2b worsens accordingly.
　本発明者は、鋭意検討の結果、フィルタ２ｂの挿入損失を劣化させている要因が上述したレイリー波リップルであり、フィルタ２ａにおける複数の弾性波共振子のうち共通端子３に最も近く接続された直列腕共振子Ｓ１が以下の（ｉ）、（ｉｉ）および（ｉｉｉ）のうちの少なくとも１つの条件を満たすことで、レイリー波リップルのリターンロスを小さくでき、ひいては、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できることを見出した。 As a result of diligent studies, the present inventor has found that the factor deteriorating the insertion loss of the filter 2b is the Rayleigh wave ripple described above, which is the closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a. When the series arm resonator S1 satisfies at least one of the following conditions (i), (ii) and (iii), the return loss of the Rayleigh wave ripple can be reduced, and thus within the pass band of the filter 2b. We have found that the deterioration of insertion loss can be suppressed.
　　（ｉ）複数の反射電極指１２ａの繰り返しピッチ／複数の電極指１１ａおよび１１ｂの繰り返しピッチ＝λＲＥＦ／λＩＤＴ≧１．０１
　　（ｉｉ）ＩＲＧＡＰ＞複数の反射電極指１２ａの繰り返しピッチ（０．５λＲＥＦ）
　　（ｉｉｉ）複数の電極指１１ａおよび１１ｂの対数≦５０対 (I) Repeated pitch of a plurality of reflective electrode fingers 12a / Repeated pitch of a plurality of electrode fingers 11a and 11b = λ REF / λ IDT ≧ 1.01
(Ii) IRGAP> Repeat pitch of a plurality of reflective electrode fingers 12a (0.5λ REF )
(Iii) Logarithm of a plurality of electrode fingers 11a and 11b ≤ 50 pairs
　直列腕共振子Ｓ１は、複数の弾性波共振子のうち共通端子３に最も近く接続されているため、複数の弾性波共振子のうちフィルタ２ａと共通端子３において共通接続されたフィルタ２ｂに最も近く接続されることになる。これは、直列腕共振子Ｓ１が、複数の弾性波共振子のうちフィルタ２ｂに最も影響を与えやすい弾性波共振子であることを意味する。このため、直列腕共振子Ｓ１に着目し、直列腕共振子Ｓ１が上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちの少なくとも１つの条件を満たすようにすることで、フィルタ２ｂの通過帯域内の挿入損失の劣化を効果的に抑制できる。 Since the series arm resonator S1 is connected closest to the common terminal 3 among the plurality of elastic wave resonators, the filter 2a and the filter 2b commonly connected at the common terminal 3 among the plurality of elastic wave resonators are the closest. It will be connected soon. This means that the series arm resonator S1 is an elastic wave resonator that most easily affects the filter 2b among the plurality of elastic wave resonators. Therefore, paying attention to the series arm resonator S1, the series arm resonator S1 satisfies at least one of the above (i), the above (ii), and the above (iii), so that the filter 2b can be used. Deterioration of insertion loss in the pass band can be effectively suppressed.
　［５．対数についての条件］
　まずは、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉｉｉ）の条件（対数についての条件）を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできることを、図４を用いて説明する。 [5. Logarithmic conditions]
First, the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators satisfies the above condition (iii) (condition for logarithm), so that the filter 2a is removed from the common terminal 3. It will be described with reference to FIG. 4 that the return loss of the Rayleigh wave ripple when viewed can be reduced.
　図４は、対数とレイリー波リップルのリターンロスとの関係を示すグラフである。なお、ここでは、λＲＥＦ／λＩＤＴ（波長比とも呼ぶ）を１．０とし、ＩＲＧＡＰをλＲＥＦの０．５倍としている。すなわち、ここでは、直列腕共振子Ｓ１は上記（ｉ）および上記（ｉｉ）の条件を満たしていないとする。 FIG. 4 is a graph showing the relationship between the logarithm and the return loss of the Rayleigh wave ripple. Here, λ REF / λ IDT (also referred to as wavelength ratio) is 1.0, and IRGAP is 0.5 times λ REF. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (i) and (ii).
　例えば、実験およびシミュレーション等によって、レイリー波リップルのリターンロスが０．５ｄＢ以下となることで、フィルタ２ｂの挿入損失の劣化を約０．１５ｄＢ以内に収めることができることがわかっている。そのため、ここでは、レイリー波リップルのリターンロスを０．５ｄＢ以下とすることを１つの目安としている。なお、レイリー波リップルのリターンロスを０．５ｄＢ以下にするというのは一例であって、０．５ｄＢ以下にすることは必須ではなく、例えば、０．６ｄＢ等を目安にしてもよい。図４に示されるように、複数の電極指１１ａおよび１１ｂの対数が少ないほどレイリー波リップルのリターンロスが小さくなっていき、傾向として複数の電極指１１ａおよび１１ｂの対数が５０対以下でレイリー波リップルのリターンロスが０．５ｄＢ以下となることがわかる。これにより、フィルタ２ｂの通過帯域内の挿入損失の劣化を約０．１５ｄＢ以内に収めることができる。 For example, by experiments and simulations, it has been found that the deterioration of the insertion loss of the filter 2b can be kept within about 0.15 dB by reducing the return loss of the Rayleigh wave ripple to 0.5 dB or less. Therefore, here, one guideline is to set the return loss of the Rayleigh wave ripple to 0.5 dB or less. It should be noted that setting the return loss of the Rayleigh wave ripple to 0.5 dB or less is an example, and it is not essential to set it to 0.5 dB or less, and for example, 0.6 dB or the like may be used as a guide. As shown in FIG. 4, the smaller the logarithm of the plurality of electrode fingers 11a and 11b, the smaller the return loss of the Rayleigh wave ripple, and the tendency is that the logarithm of the plurality of electrode fingers 11a and 11b is 50 pairs or less and the Rayleigh wave. It can be seen that the return loss of the ripple is 0.5 dB or less. As a result, the deterioration of the insertion loss in the pass band of the filter 2b can be kept within about 0.15 dB.
　このように、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が少なくとも上記（ｉｉｉ）の条件を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできる。したがって、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できる。 As described above, when the filter 2a is viewed from the common terminal 3 by satisfying at least the above condition (iii) in the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators. The return loss of Rayleigh wave ripple can be reduced. Therefore, it is possible to suppress the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator.
　［６．波長比についての条件］
　次に、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉ）の条件（波長比についての条件）を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできることを、図５を用いて説明する。 [6. Conditions for wavelength ratio]
Next, the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators satisfies the condition (i) above (condition for wavelength ratio), so that the filter is filtered from the common terminal 3. It will be described with reference to FIG. 5 that the return loss of the Rayleigh wave ripple when looking at 2a can be reduced.
　図５は、波長比とレイリー波リップルのリターンロスとの関係を示すグラフである。なお、ここでは、ＩＲＧＡＰをλＲＥＦの０．５倍とし、複数の電極指の対数を８０対としている。すなわち、ここでは、直列腕共振子Ｓ１は、上記（ｉｉ）および上記（ｉｉｉ）の条件を満たしていないとする。 FIG. 5 is a graph showing the relationship between the wavelength ratio and the return loss of Rayleigh wave ripple. Here, IRGAP is 0.5 times λ REF , and the logarithm of a plurality of electrode fingers is 80 pairs. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (ii) and (iii).
　図５に示されるように、波長比が大きいほどレイリー波リップルのリターンロスが小さくなっていき、波長比が１．０１以上のとき、具体的には、１．０１３（図５における細い破線）、１．０２４（図５における太い破線）および１．０３５（図５における太い点線）のときに、レイリー波リップルのリターンロスが０．５ｄＢ以下となっていることがわかる。これにより、フィルタ２ｂの通過帯域内の挿入損失の劣化を約０．１５ｄＢ以内に収めることができる。 As shown in FIG. 5, the larger the wavelength ratio, the smaller the return loss of the Rayleigh wave ripple, and when the wavelength ratio is 1.01 or more, specifically 1.013 (thin broken line in FIG. 5). , 1.024 (thick broken line in FIG. 5) and 1.035 (thick dotted line in FIG. 5), it can be seen that the return loss of the Rayleigh wave ripple is 0.5 dB or less. As a result, the deterioration of the insertion loss in the pass band of the filter 2b can be kept within about 0.15 dB.
　このように、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が少なくとも上記（ｉ）の条件を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできる。したがって、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できる。 In this way, when the filter 2a is viewed from the common terminal 3 by satisfying at least the condition of (i) above, the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators. The return loss of Rayleigh wave ripple can be reduced. Therefore, it is possible to suppress the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator.
　［７．ＩＲＧＡＰについての条件］
　次に、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉｉ）の条件であるＩＲＧＡＰについての条件を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできることを、図６を用いて説明する。 [7. Conditions for IRGAP]
Next, the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators satisfies the condition for IRGAP which is the condition (ii) above, so that the filter 2a from the common terminal 3 It will be described with reference to FIG. 6 that the return loss of the Rayleigh wave ripple can be reduced when viewed.
　図６は、ＩＲＧＡＰとレイリー波リップルのリターンロスとの関係を示すグラフである。なお、ここでは、波長比を１．０とし、複数の電極指の対数を８０対としている。すなわち、ここでは、直列腕共振子Ｓ１は、上記（ｉ）および上記（ｉｉｉ）の条件を満たしていないとする。 FIG. 6 is a graph showing the relationship between IRGAP and the return loss of Rayleigh wave ripple. Here, the wavelength ratio is 1.0, and the logarithm of the plurality of electrode fingers is 80 pairs. That is, here, it is assumed that the series arm resonator S1 does not satisfy the above conditions (i) and (iii).
　図６に示されるように、ＩＲＧＡＰが大きいほどレイリー波リップルのリターンロスが小さくなっていき、ＩＲＧＡＰがλＲＥＦの０．５倍よりも大きいとき、具体的には、ＩＲＧＡＰがλＲＥＦの０．６倍（図６における太い点線）のときに、レイリー波リップルのリターンロスが０．５ｄＢ以下となることがわかる。これにより、フィルタ２ｂの通過帯域内の挿入損失の劣化を約０．１５ｄＢ以内に収めることができる。 As shown in FIG. 6, IRGAP is gradually higher is the return loss of the Rayleigh wave ripple small large, is greater than 0.5 times the IRGAP is lambda REF, specifically, 0 IRGAP of lambda REF. It can be seen that the return loss of the Rayleigh wave ripple is 0.5 dB or less at 6 times (thick dotted line in FIG. 6). As a result, the deterioration of the insertion loss in the pass band of the filter 2b can be kept within about 0.15 dB.
　このように、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が少なくとも上記（ｉｉ）の条件を満たすことで、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくできる。したがって、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できる。 In this way, when the filter 2a is viewed from the common terminal 3 by satisfying at least the condition of (ii) above, the series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators. The return loss of Rayleigh wave ripple can be reduced. Therefore, it is possible to suppress the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator.
　［８．実施例および比較例の比較］
　次に、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉ）の条件を満たしている実施例と、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のいずれの条件も満たしていない比較例とを比較結果を図７から図１０を用いて説明する。 [8. Comparison of Examples and Comparative Examples]
Next, the embodiment in which the series arm resonator S1 closest to the common terminal 3 among the plurality of elastic wave resonators satisfies the above condition (i) and the plurality of elastic wave resonators are common. The results of comparison with the comparative example in which the series arm resonator S1 closest to the terminal 3 does not satisfy any of the above conditions (i), (ii), and (iii) are shown in FIGS. 7 to 10. It will be explained using.
　まずは、比較例について説明する。 First, a comparative example will be explained.
　比較例では、直列腕共振子Ｓ１について、波長比が１．００２、ＩＲＧＡＰがλＲＥＦの０．４５倍、複数の電極指１１ａおよび１１ｂの対数が１５０．５対となっており、直列腕共振子Ｓ１は、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のいずれの条件も満たしていない。 In the comparative example, the wavelength ratio of the series arm resonator S1 is 1.002, the IRGAP is 0.45 times that of λ REF , and the logarithm of the plurality of electrode fingers 11a and 11b is 150.5 pairs. The child S1 does not satisfy any of the above conditions (i), (ii), and (iii).
　図７は、比較例に係る第１フィルタ（フィルタ２ａ）の通過特性を示すグラフである。 FIG. 7 is a graph showing the passing characteristics of the first filter (filter 2a) according to the comparative example.
　図８は、比較例に係る第１フィルタ（フィルタ２ａ）の共通端子３側から見たリターンロス特性を示すグラフである。 FIG. 8 is a graph showing the return loss characteristics seen from the common terminal 3 side of the first filter (filter 2a) according to the comparative example.
　比較例では、直列腕共振子Ｓ１が、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のいずれの条件も満たしていないため、図７の破線の丸で囲った箇所のように、フィルタ２ａの通過帯域（Ｂａｎｄ７Ｒｘ）に含まれる周波数の約０．７６倍の周波数と重複するフィルタ２ｂの通過帯域（Ｂａｎｄ１Ｒｘ）においてレイリー波リップルが発生していることがわかる。このレイリー波リップルが発生した周波数では、共通端子３からフィルタ２ａを見た場合の反射係数が悪化（低下）、言い換えると、リターンロスが増加するため、図８の破線の丸で囲った箇所のように、約１．７ｄＢとレイリー波リップルのリターンロスが大きくなっていることがわかる。 In the comparative example, since the series arm resonator S1 does not satisfy any of the above conditions (i), (ii), and (iii), the filter is as shown by the circled portion of the broken line in FIG. It can be seen that Rayleigh wave ripple occurs in the pass band (Band1Rx) of the filter 2b which overlaps with the frequency of about 0.76 times the frequency included in the pass band (Band7Rx) of 2a. At the frequency at which this Rayleigh wave ripple occurs, the reflectance coefficient when the filter 2a is viewed from the common terminal 3 deteriorates (decreases), in other words, the return loss increases. As described above, it can be seen that the return loss of the Rayleigh wave ripple is large at about 1.7 dB.
　次に、実施例について比較例と比較しながら説明する。 Next, the examples will be described while comparing with the comparative examples.
　実施例では、直列腕共振子Ｓ１について、波長比が１．０２５、ＩＲＧＡＰがλＲＥＦの０．５倍、複数の電極指１１ａおよび１１ｂの対数が８５対となっており、直列腕共振子Ｓ１は、上記（ｉ）の条件を満たしている。 In the embodiment, the series arm resonator S1 has a wavelength ratio of 1.025, an IRGAP of 0.5 times that of λ REF , and a logarithm of a plurality of electrode fingers 11a and 11b having 85 pairs. Satisfies the condition of (i) above.
　図９は、実施例および比較例に係る第１フィルタ（フィルタ２ａ）の共通端子３側から見たリターンロス特性を比較したグラフである。 FIG. 9 is a graph comparing the return loss characteristics seen from the common terminal 3 side of the first filter (filter 2a) according to the examples and the comparative examples.
　図１０は、実施例および比較例に係る第２フィルタ（フィルタ２ｂ）に接続された増幅回路のゲイン特性を示すグラフである。 FIG. 10 is a graph showing the gain characteristics of the amplifier circuit connected to the second filter (filter 2b) according to the examples and the comparative examples.
　実施例では、直列腕共振子Ｓ１が、上記（ｉ）の条件を満たしているため、図示はしていないが、フィルタ２ａの通過帯域（Ｂａｎｄ７Ｒｘ）に含まれる周波数の約０．７６倍の周波数と重複するフィルタ２ｂの通過帯域（Ｂａｎｄ１Ｒｘ）において発生するレイリー波リップルが小さくなる。このため、図９に示されるように、比較例（図９における破線）では約１．７ｄＢとなっているレイリー波リップルのリターンロスが、実施例（図９における実線）では約０．６ｄＢと大きく改善していることがわかる。その結果、実施例では、比較例と比べてフィルタ２ｂの通過帯域内の挿入損失の劣化を抑制することができる。図１０の破線の丸で囲った箇所に示されるように、比較例（図１０における破線）では、フィルタ２ｂの通過帯域内の挿入損失の劣化によって、フィルタ２ｂに接続された増幅回路のゲインも劣化しているが、実施例（図１０における実線）では、比較例と比べてフィルタ２ｂに接続された増幅回路のゲインも大きく改善していることがわかる。 In the embodiment, since the series arm resonator S1 satisfies the condition (i) above, it is not shown, but the frequency is about 0.76 times the frequency included in the pass band (Band7Rx) of the filter 2a. The Rayleigh wave ripple generated in the pass band (Band1Rx) of the filter 2b overlapping with the filter 2b becomes smaller. Therefore, as shown in FIG. 9, the return loss of the Rayleigh wave ripple, which is about 1.7 dB in the comparative example (broken line in FIG. 9), is about 0.6 dB in the embodiment (solid line in FIG. 9). It can be seen that there is a great improvement. As a result, in the examples, deterioration of the insertion loss in the pass band of the filter 2b can be suppressed as compared with the comparative example. As shown in the circled part of the broken line in FIG. 10, in the comparative example (broken line in FIG. 10), the gain of the amplifier circuit connected to the filter 2b is also increased due to the deterioration of the insertion loss in the pass band of the filter 2b. Although it has deteriorated, it can be seen that in the embodiment (solid line in FIG. 10), the gain of the amplifier circuit connected to the filter 2b is also greatly improved as compared with the comparative example.
　なお、複数の弾性波共振子のうち共通端子３に最も近く接続されている直列腕共振子Ｓ１が上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちのいずれか１つの条件を満たしているときに、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できることを示したが、直列腕共振子Ｓ１が上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちの２つの条件、または、その全ての条件を満たす場合には、さらなる改善を図ることができる。 The series arm resonator S1 connected closest to the common terminal 3 among the plurality of elastic wave resonators satisfies any one of the above conditions (i), (ii), and (iii). It was shown that the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator can be suppressed, but the series arm resonator S1 has the above (i), the above (ii) and Further improvement can be achieved if two of the above two conditions (iii) or all of them are satisfied.
　［９．変形例］
　なお、フィルタ２ａは、図２に示される構成に限らず、例えば、図１１または図１２に示されるような構成であってもよい。 [9. Modification example]
The filter 2a is not limited to the configuration shown in FIG. 2, and may have a configuration as shown in FIG. 11 or FIG. 12, for example.
　図１１および図１２は、実施の形態に係る第１フィルタ（フィルタ２ａ）の変形例を示す回路構成図である。 11 and 12 are circuit configuration diagrams showing a modified example of the first filter (filter 2a) according to the embodiment.
　図１１に示されるように、フィルタ２ａは、縦結合型共振器Ｍ１を備えていてもよい。図１１に示されるフィルタ２ａは、図２に示されるフィルタ２ａと同じように、直列腕共振子Ｓ１およびＳ２ならびに並列腕共振子Ｐ１を備え、直列腕共振子Ｓ２と入出力端子４ａとを結ぶ経路上に縦結合型共振器Ｍ１が配置されている。この場合、フィルタ２ａが備える複数の弾性波共振子のうち第１弾性波共振子（ここでは直列腕共振子Ｓ１）を除く少なくとも１つの弾性波共振子は、縦結合型共振器Ｍ１を構成する。例えば、縦結合型共振器Ｍ１は、縦結合共振子Ｎ１、Ｎ２、Ｎ３、Ｎ４およびＮ５を備える５電極型の縦結合型共振器であり、上記少なくとも１つの弾性波共振子は、縦結合共振子Ｎ１、Ｎ２、Ｎ３、Ｎ４およびＮ５となる。 As shown in FIG. 11, the filter 2a may include a vertically coupled resonator M1. The filter 2a shown in FIG. 11 includes series arm resonators S1 and S2 and a parallel arm resonator P1 in the same manner as the filter 2a shown in FIG. 2, and connects the series arm resonator S2 and the input / output terminal 4a. A vertically coupled resonator M1 is arranged on the path. In this case, at least one elastic wave resonator other than the first elastic wave resonator (here, the series arm resonator S1) among the plurality of elastic wave resonators included in the filter 2a constitutes the longitudinal coupling type resonator M1. .. For example, the longitudinally coupled resonator M1 is a 5-electrode type longitudinally coupled resonator provided with longitudinally coupled resonators N1, N2, N3, N4 and N5, and the at least one elastic wave resonator is a longitudinally coupled resonator. It becomes children N1, N2, N3, N4 and N5.
　例えば、図１１に示されるフィルタ２ａは、直列腕共振子Ｓ２および並列腕共振子Ｐ１を備えていなくてもよい。つまり、フィルタ２ａは、直列腕共振子Ｓ１および縦結合型共振器Ｍ１のみからなるフィルタであってもよい。この場合、フィルタ２ａは、直列腕共振子Ｓ１ならびに縦結合型共振器Ｍ１を構成する縦結合共振子Ｎ１、Ｎ２、Ｎ３、Ｎ４およびＮ５を備え、すなわち、複数の弾性波共振子を備えることになり、直列腕共振子Ｓ１は、複数の弾性波共振子のうち共通端子３に最も近く接続されている第１弾性波共振子となる。 For example, the filter 2a shown in FIG. 11 may not include the series arm resonator S2 and the parallel arm resonator P1. That is, the filter 2a may be a filter composed of only the series arm resonator S1 and the vertically coupled resonator M1. In this case, the filter 2a includes the series arm resonator S1 and the longitudinally coupled resonators N1, N2, N3, N4 and N5 constituting the longitudinally coupled resonator M1, that is, includes a plurality of elastic wave resonators. The series arm resonator S1 is the first elastic wave resonator connected to the common terminal 3 among the plurality of elastic wave resonators.
　また、図２および図１１では、フィルタ２ａにおける複数の弾性波共振子のうち共通端子３に最も近く接続されている第１弾性波共振子は、共通端子３と入出力端子４ａとを結ぶ経路上に配置された直列腕共振子Ｓ１であるが、図１２に示される変形例では、フィルタ２ａにおける複数の弾性波共振子のうち共通端子３に最も近く接続されている第１弾性波共振子は、共通端子３と入出力端子４ａとを結ぶ経路上のノードとグランドとの間に接続された並列腕共振子Ｐ１である。なお、図１２に示される変形例において、第１弾性波共振子は、並列腕共振子Ｐ１および直列腕共振子Ｓ２の両方であってもよい。直列腕共振子Ｓ２は、並列腕共振子Ｐ１と同じノードに接続されており、並列腕共振子Ｐ１と同じように、共通端子３に最も近く接続されているといえるためである。このため、並列腕共振子Ｐ１および直列腕共振子Ｓ２の両方が、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちの少なくとも１つの条件を満たしていてもよい。あるいは、図１２に示される変形例において、直列腕共振子Ｓ２だけが、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちの少なくとも１つの条件を満たしていてもよい。つまり、図１２に示される変形例において、並列腕共振子Ｐ１は、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちのいずれの条件も満たしていなくてもよい。 Further, in FIGS. 2 and 11, among the plurality of elastic wave resonators in the filter 2a, the first elastic wave resonator connected closest to the common terminal 3 is a path connecting the common terminal 3 and the input / output terminal 4a. Although the series arm resonator S1 is arranged above, in the modified example shown in FIG. 12, the first elastic wave resonator connected closest to the common terminal 3 among the plurality of elastic wave resonators in the filter 2a. Is a parallel arm resonator P1 connected between a node on the path connecting the common terminal 3 and the input / output terminal 4a and the ground. In the modified example shown in FIG. 12, the first elastic wave resonator may be both the parallel arm resonator P1 and the series arm resonator S2. This is because the series arm resonator S2 is connected to the same node as the parallel arm resonator P1, and can be said to be connected closest to the common terminal 3 like the parallel arm resonator P1. Therefore, both the parallel arm resonator P1 and the series arm resonator S2 may satisfy at least one of the above conditions (i), the above (ii), and the above (iii). Alternatively, in the modification shown in FIG. 12, only the series arm resonator S2 may satisfy at least one of the above conditions (i), the above (ii), and the above (iii). That is, in the modification shown in FIG. 12, the parallel arm resonator P1 may not satisfy any of the above conditions (i), (ii), and (iii).
　［１０．まとめ］
　以上説明したように、マルチプレクサ１は、共通端子３、入出力端子４ａおよび４ｂと、共通端子３と入出力端子４ａとの間に接続されるフィルタ２ａと、共通端子３と入出力端子４ｂとの間に接続されるフィルタ２ｂと、を備える。フィルタ２ｂの通過帯域は、フィルタ２ａの通過帯域の０．７５倍から０．８倍の帯域と少なくとも一部が重なる。フィルタ２ａは、複数の弾性波共振子を備え、複数の弾性波共振子のうち共通端子３に最も近く接続された第１弾性波共振子は、圧電体層を有する基板上に形成された、ＩＤＴ電極１１と、ＩＤＴ電極１１と弾性波伝搬方向に隣り合って配置された反射器１２と、を備える。ＩＤＴ電極１１は、弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の電極指１１ａおよび１１ｂで構成される。反射器１２は、弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の反射電極指１２ａで構成される。第１弾性波共振子は、以下の（ｉ）、（ｉｉ）および（ｉｉｉ）のうちの少なくとも１つの条件を満たす。（ｉ）複数の反射電極指１２ａの繰り返しピッチ／複数の電極指１１ａおよび１１ｂの繰り返しピッチ≧１．０１。（ｉｉ）複数の電極指１１ａおよび１１ｂのうち反射器１２に最近接する電極指の中心と複数の反射電極指１２ａのうちＩＤＴ電極１１に最近接する反射電極指１２ａの中心との距離（ＩＲＧＡＰ）＞複数の反射電極指１２ａの繰り返しピッチ。（ｉｉｉ）複数の電極指１１ａおよび１１ｂの対数≦５０対。 [10. summary]
As described above, the multiplexer 1 includes a common terminal 3, input / output terminals 4a and 4b, a filter 2a connected between the common terminal 3 and the input / output terminal 4a, and a common terminal 3 and an input / output terminal 4b. A filter 2b connected between the two. The pass band of the filter 2b overlaps at least a part of the band 0.75 to 0.8 times the pass band of the filter 2a. The filter 2a includes a plurality of elastic wave resonators, and the first elastic wave resonator connected closest to the common terminal 3 among the plurality of elastic wave resonators is formed on a substrate having a piezoelectric layer. The IDT electrode 11 and the reflector 12 arranged adjacent to the IDT electrode 11 in the elastic wave propagation direction are provided. The IDT electrode 11 is composed of a plurality of electrode fingers 11a and 11b extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other. The reflector 12 is composed of a plurality of reflective electrode fingers 12a extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other. The first elastic wave resonator satisfies at least one of the following conditions (i), (ii) and (iii). (I) Repeated pitch of the plurality of reflective electrode fingers 12a / Repeated pitch of the plurality of electrode fingers 11a and 11b ≧ 1.01. (Ii) Distance between the center of the electrode finger closest to the reflector 12 among the plurality of electrode fingers 11a and 11b and the center of the reflective electrode finger 12a closest to the IDT electrode 11 among the plurality of reflective electrode fingers 12a (IRGAP)> Repeated pitch of multiple reflective electrode fingers 12a. (Iii) Logarithm of a plurality of electrode fingers 11a and 11b ≤ 50 pairs.
　これによれば、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスを小さくでき、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化を抑制できる。 According to this, the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 can be reduced, and the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator can be suppressed. ..
　例えば、マルチプレクサ１は、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）のうちの少なくとも２つの条件を満たしていてもよい。さらに、例えば、マルチプレクサ１は、上記（ｉ）、上記（ｉｉ）および上記（ｉｉｉ）の全ての条件を満たしていてもよい。 For example, the multiplexer 1 may satisfy at least two conditions of the above (i), the above (ii), and the above (iii). Further, for example, the multiplexer 1 may satisfy all the conditions of the above (i), the above (ii), and the above (iii).
　これによれば、共通端子３からフィルタ２ａを見た場合のレイリー波リップルのリターンロスをさらに小さくでき、弾性波共振子のレイリー波リップルによる、フィルタ２ｂの通過帯域内の挿入損失の劣化をさらに抑制できる。 According to this, the return loss of the Rayleigh wave ripple when the filter 2a is viewed from the common terminal 3 can be further reduced, and the deterioration of the insertion loss in the pass band of the filter 2b due to the Rayleigh wave ripple of the elastic wave resonator is further reduced. Can be suppressed.
　例えば、第１弾性波共振子は、図２または図１１に示されるように、共通端子３と入出力端子４ａとを結ぶ経路上に配置された直列腕共振子Ｓ１であってもよいし、図１２に示されるように、共通端子３と入出力端子４ａとを結ぶ経路上のノードとグランドとの間に接続された並列腕共振子Ｐ１であってもよい。 For example, the first elastic wave resonator may be a series arm resonator S1 arranged on a path connecting the common terminal 3 and the input / output terminal 4a, as shown in FIG. 2 or FIG. As shown in FIG. 12, it may be a parallel arm resonator P1 connected between a node on the path connecting the common terminal 3 and the input / output terminal 4a and the ground.
　例えば、フィルタ２ａは、図２に示されるように、ラダー型フィルタであってもよい。 For example, the filter 2a may be a ladder type filter as shown in FIG.
　例えば、図１１に示されるように、複数の弾性波共振子のうちの第１弾性波共振子を除く少なくとも１つの弾性波共振子は、縦結合型共振器Ｍ１を構成していてもよい。 For example, as shown in FIG. 11, at least one elastic wave resonator other than the first elastic wave resonator among the plurality of elastic wave resonators may constitute the longitudinal coupling type resonator M1.
　（その他の実施の形態）
　以上、本発明の実施の形態に係るマルチプレクサ１について説明したが、本発明は、上記実施の形態における任意の構成要素を組み合わせて実現される別の実施の形態や、上記実施の形態に対して本発明の主旨を逸脱しない範囲で当業者が思いつく各種変形を施して得られる変形例も本発明に含まれる。 (Other embodiments)
Although the multiplexer 1 according to the embodiment of the present invention has been described above, the present invention relates to another embodiment realized by combining arbitrary components in the above embodiment and the above embodiment. The present invention also includes modifications obtained by performing various modifications that can be conceived by those skilled in the art without departing from the gist of the present invention.
　例えば、実施の形態に係るマルチプレクサ１は、高周波フロントエンド回路、さらには高周波フロントエンド回路を備える通信装置に適用することが可能である。マルチプレクサ１が適用された高周波フロントエンド回路および通信装置を内蔵した各種機器も本発明に含まれる。 For example, the multiplexer 1 according to the embodiment can be applied to a communication device including a high frequency front end circuit and further a high frequency front end circuit. The present invention also includes various devices incorporating a high-frequency front-end circuit to which the multiplexer 1 is applied and a communication device.
　例えば、実施の形態に係るフィルタ２ａにおける複数の弾性波共振子の数は、２つであってもよい。 For example, the number of the plurality of elastic wave resonators in the filter 2a according to the embodiment may be two.
　例えば、実施の形態に係るフィルタ２ｂは、弾性波フィルタでなくてもよく、ＬＣフィルタ等であってもよい。 For example, the filter 2b according to the embodiment may not be an elastic wave filter, but may be an LC filter or the like.
　本発明は、マルチバンドシステムに適用できるマルチプレクサとして、携帯電話などの通信機器に広く利用できる。 The present invention can be widely used in communication devices such as mobile phones as a multiplexer applicable to a multi-band system.
　１　　マルチプレクサ
　２ａ、２ｂ　　フィルタ
　３　　共通端子
　４ａ、４ｂ　　入出力端子
　１０　　弾性波共振子
　１１　　ＩＤＴ電極
　１１ａ、１１ｂ　　電極指
　１１Ａ、１１Ｂ　　櫛歯状電極
　１１ｃ、１２ｃ　　バスバー電極
　１２　　反射器
　１２ａ　　反射電極指
　１００　　圧電基板
　１１０　　電極
　１１１　　密着層
　１１２　　主電極層
　１１３　　保護膜
　ＡＮＴ　　アンテナ素子
　Ｍ１　　縦結合型共振器
　Ｎ１、Ｎ２、Ｎ３、Ｎ４、Ｎ５　　縦結合共振子
　Ｐ１、Ｐ２、Ｐ３、Ｐ４　　並列腕共振子
　Ｓ１、Ｓ２、Ｓ３、Ｓ４　　直列腕共振子 1 multiplexer 2a, 2b filter 3 common terminal 4a, 4b input / output terminal 10 elastic wave resonator 11 IDT electrode 11a, 11b electrode finger 11A, 11B comb tooth electrode 11c, 12c bus bar electrode 12 reflector 12a reflective electrode finger 100 piezoelectric substrate 110 Electrode 111 Adhesion layer 112 Main electrode layer 113 Protective film ANT Antenna element M1 Vertical coupling type resonator N1, N2, N3, N4, N5 Vertical coupling resonator P1, P2, P3, P4 Parallel arm resonator S1, S2, S3 , S4 series arm resonator

Claims (7)

  1. 　共通端子、第１入出力端子および第２入出力端子と、
    　前記共通端子と前記第１入出力端子との間に接続される第１フィルタと、
    　前記共通端子と前記第２入出力端子との間に接続される第２フィルタと、を備え、
    　前記第２フィルタの通過帯域は、前記第１フィルタの通過帯域の０．７５倍から０．８倍の帯域と少なくとも一部が重なり、
    　前記第１フィルタは、複数の弾性波共振子を備え、
    　前記複数の弾性波共振子のうち前記共通端子に最も近く接続された第１弾性波共振子は、圧電体層を有する基板上に形成された、ＩＤＴ電極と、前記ＩＤＴ電極と弾性波伝搬方向に隣り合って配置された反射器と、を備え、
    　前記ＩＤＴ電極は、前記弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の電極指で構成され、
    　前記反射器は、前記弾性波伝搬方向と交差する方向に延伸し、互いに平行に配置された複数の反射電極指で構成され、
    　前記第１弾性波共振子は、以下の（ｉ）、（ｉｉ）および（ｉｉｉ）のうちの少なくとも１つの条件を満たす
    　（ｉ）前記複数の反射電極指の繰り返しピッチ／前記複数の電極指の繰り返しピッチ≧１．０１
    　（ｉｉ）前記複数の電極指のうち前記反射器に最近接する電極指の中心と前記複数の反射電極指のうち前記ＩＤＴ電極に最近接する反射電極指の中心との距離＞前記複数の反射電極指の繰り返しピッチ
    　（ｉｉｉ）前記複数の電極指の対数≦５０対
    　マルチプレクサ。     Common terminal, 1st input / output terminal and 2nd input / output terminal,
    A first filter connected between the common terminal and the first input / output terminal,
    A second filter connected between the common terminal and the second input / output terminal is provided.
    The pass band of the second filter overlaps at least a part of the band 0.75 to 0.8 times the pass band of the first filter.
    The first filter includes a plurality of elastic wave resonators.
    Among the plurality of elastic wave resonators, the first elastic wave resonator connected closest to the common terminal is an IDT electrode formed on a substrate having a piezoelectric layer, and the IDT electrode and the elastic wave propagation direction. With reflectors placed next to each other,
    The IDT electrode is composed of a plurality of electrode fingers extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other.
    The reflector is composed of a plurality of reflective electrode fingers extending in a direction intersecting the elastic wave propagation direction and arranged in parallel with each other.
    The first elastic wave resonator satisfies at least one of the following (i), (ii) and (iii) (i) Repeated pitch of the plurality of reflective electrode fingers / of the plurality of electrode fingers. Repeat pitch ≧ 1.01
    (Ii) Distance between the center of the electrode finger closest to the reflector among the plurality of electrode fingers and the center of the reflective electrode finger closest to the IDT electrode among the plurality of reflective electrode fingers> the plurality of reflective electrode fingers Repeat pitch (iii) Log of the plurality of electrode fingers ≤ 50 pairs multiplexer.
  2. 　前記第１弾性波共振子は、前記（ｉ）、前記（ｉｉ）および前記（ｉｉｉ）のうちの少なくとも２つの条件を満たす
    　請求項１に記載のマルチプレクサ。     The multiplexer according to claim 1, wherein the first elastic wave resonator satisfies at least two conditions of (i), (ii), and (iii).
  3. 　前記第１弾性波共振子は、前記（ｉ）、前記（ｉｉ）および前記（ｉｉｉ）の全ての条件を満たす
    　請求項１に記載のマルチプレクサ。     The multiplexer according to claim 1, wherein the first elastic wave resonator satisfies all of the above conditions (i), (ii), and (iii).
  4. 　前記第１弾性波共振子は、前記共通端子と前記第１入出力端子とを結ぶ経路上に配置された直列腕共振子である
    　請求項１～３のいずれか１項に記載のマルチプレクサ。     The multiplexer according to any one of claims 1 to 3, wherein the first elastic wave resonator is a series arm resonator arranged on a path connecting the common terminal and the first input / output terminal.
  5. 　前記第１弾性波共振子は、前記共通端子と前記第１入出力端子とを結ぶ経路上のノードとグランドとの間に接続された並列腕共振子である
    　請求項１～３のいずれか１項に記載のマルチプレクサ。     The first elastic wave resonator is any one of claims 1 to 3 which is a parallel arm resonator connected between a node on the path connecting the common terminal and the first input / output terminal and the ground. The multiplexer described in the section.
  6. 　前記第１フィルタは、ラダー型フィルタである
    　請求項１～５のいずれか１項に記載のマルチプレクサ。     The multiplexer according to any one of claims 1 to 5, wherein the first filter is a ladder type filter.
  7. 　前記第１フィルタには、縦結合型共振器が含まれ、
    　前記複数の弾性波共振子のうちの前記第１弾性波共振子を除く少なくとも１つの弾性波共振子は、前記縦結合型共振器を構成する
    　請求項１～６のいずれか１項に記載のマルチプレクサ。     The first filter includes a longitudinally coupled resonator.
    The method according to any one of claims 1 to 6, wherein at least one elastic wave resonator other than the first elastic wave resonator among the plurality of elastic wave resonators constitutes the vertically coupled resonator. Multiplexer.
PCT/JP2021/024085 2020-07-08 2021-06-25 Multiplexer WO2022009692A1 (en)

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