WO2023074373A1 - Résonateur à ondes élastiques, dispositif de filtre à ondes élastiques et multiplexeur - Google Patents

Résonateur à ondes élastiques, dispositif de filtre à ondes élastiques et multiplexeur Download PDF

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Publication number
WO2023074373A1
WO2023074373A1 PCT/JP2022/038059 JP2022038059W WO2023074373A1 WO 2023074373 A1 WO2023074373 A1 WO 2023074373A1 JP 2022038059 W JP2022038059 W JP 2022038059W WO 2023074373 A1 WO2023074373 A1 WO 2023074373A1
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reflector
idt
comb
wavelength
electrode
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PCT/JP2022/038059
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English (en)
Japanese (ja)
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真之 石瀧
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株式会社村田製作所
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/70—Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
    • H03H9/72—Networks using surface acoustic waves

Definitions

  • the present invention relates to elastic wave resonators, elastic wave filter devices, and multiplexers.
  • multi-band systems have been used to improve the data transmission speed of mobile phones.
  • transmission and reception may be performed in a plurality of frequency bands
  • a plurality of filter devices that pass high-frequency signals of different frequency bands are arranged in the front-end circuit of the mobile phone.
  • the plurality of filter devices are required to be small, have high isolation from adjacent bands, and have low loss in the passband.
  • Patent Document 1 discloses an elastic wave filter device formed by combining a plurality of elastic wave resonators.
  • the elastic wave resonator is composed of an IDT electrode formed on a piezoelectric substrate, and first and second reflectors formed on both sides of the IDT electrode in the propagation direction of the elastic wave.
  • the flatness of the pass band is improved by making the arrangement pitch of the electrode fingers of the first reflector and the arrangement pitch of the electrode fingers of the second reflector different.
  • an unnecessary response may occur in a predetermined frequency band. If an unnecessary response occurs in a predetermined frequency band, for example, the insertion loss in the passband of the acoustic wave filter device increases, resulting in deterioration of the pass characteristics of the acoustic wave filter device.
  • the present invention has been made to solve the above problems, and an object of the present invention is to provide an elastic wave resonator or the like that can suppress the occurrence of unnecessary responses.
  • an elastic wave resonator is provided on a piezoelectric substrate and includes a plurality of comb-teeth electrode fingers extending in a first direction parallel to the main surface of the piezoelectric substrate.
  • the pair of comb-shaped electrodes includes the plurality of comb-teeth electrode fingers extending in the first direction and arranged along the second direction, and a bus bar electrode connecting one ends of each of the plurality of comb-teeth electrode fingers.
  • the first reflector has a plurality of first reflective electrode fingers extending in the first direction and arranged along the second direction
  • the second reflector comprises the first a plurality of second reflective electrode fingers extending in the direction and arranged along the second direction, at twice the arrangement pitch of the plurality of first reflective electrode fingers arranged along the second direction
  • a certain first reflector wavelength is larger than a second reflector wavelength that is twice the arrangement pitch of the plurality of second reflective electrode fingers arranged along the second direction, and the plurality of comb teeth are arranged along the second direction.
  • a first distance which is a distance between a center of a comb-teeth electrode finger closest to the first reflector among electrode fingers and a center of a first reflective electrode finger closest to the IDT electrode among the plurality of first reflective electrode fingers.
  • the IDT-reflector gap is defined by the center of the comb-shaped electrode finger closest to the second reflector among the plurality of comb-shaped electrode fingers and the second reflector closest to the IDT electrode among the plurality of second reflective electrode fingers. less than the second IDT-reflector gap, which is the distance to the center of the electrode finger.
  • an elastic wave filter device is an elastic wave filter device including a plurality of the above elastic wave resonators, the plurality of elastic wave resonators having two inputs.
  • the first reflector wavelength is twice the arrangement pitch of the plurality of comb-tooth electrode fingers of the pair of comb-shaped electrodes;
  • the difference between the value obtained by dividing by the IDT wavelength and the value obtained by dividing the second reflector wavelength by the IDT wavelength is, in at least one parallel arm resonator among the one or more parallel arm resonators, the first A value obtained by dividing one reflector wavelength by an IDT wavelength that is twice the arrangement pitch of the plurality of comb-teeth electrode fingers of the pair of comb-shaped electrodes, and a value obtained by dividing the second reflector wavelength by the IDT wavelength. greater than the difference between
  • a multiplexer includes a plurality of filters including the acoustic wave filter device described above, and one input/output terminal of each of the plurality of filters is directly connected to a common terminal. connected directly or indirectly.
  • an elastic wave resonator is provided on a piezoelectric substrate and includes a plurality of comb-teeth electrode fingers extending in a first direction parallel to the main surface of the piezoelectric substrate.
  • the pair of comb-shaped electrodes includes the plurality of comb-teeth electrode fingers extending in the first direction and arranged along the second direction, and a bus bar electrode connecting one ends of each of the plurality of comb-teeth electrode fingers.
  • the first reflector has a plurality of first reflective electrode fingers extending in the first direction and arranged along the second direction
  • the second reflector comprises the first a plurality of second reflective electrode fingers extending in the direction and arranged along the second direction, at twice the arrangement pitch of the plurality of first reflective electrode fingers arranged along the second direction
  • a certain first reflector wavelength is larger than a second reflector wavelength that is twice the arrangement pitch of the plurality of second reflective electrode fingers arranged along the second direction, and the plurality of comb teeth are arranged along the second direction.
  • a first distance which is a distance between a center of a comb-teeth electrode finger closest to the first reflector among electrode fingers and a center of a first reflective electrode finger closest to the IDT electrode among the plurality of first reflective electrode fingers.
  • the IDT-reflector gap is defined by the center of the comb-shaped electrode finger closest to the second reflector among the plurality of comb-shaped electrode fingers and the second reflector closest to the IDT electrode among the plurality of second reflective electrode fingers. Greater than the second IDT-reflector gap, which is the distance to the center of the electrode finger.
  • FIG. 1 is a diagram showing a circuit configuration of an acoustic wave filter device according to Embodiment 1.
  • FIG. FIG. 2 is a diagram schematically showing an electrode configuration of elastic wave resonators included in the elastic wave filter device.
  • FIG. 3 is a diagram showing reflector wavelengths, IDT-reflector gaps, return losses, etc. of elastic wave resonators of Comparative Example 1 and Examples 1 and 2.
  • FIG. 4 is a diagram showing return losses of elastic wave resonators of Comparative Example 1 and Examples 1 and 2.
  • FIG. FIG. 5 is a diagram showing electrode parameters and the like of series arm resonators and parallel arm resonators included in the elastic wave filter device of Example 3.
  • FIG. 6 is a diagram showing reflector wavelengths, IDT-reflector gaps, etc. of series arm resonators and parallel arm resonators included in acoustic wave filter devices of Example 3 and Comparative Examples 2 and 3.
  • FIG. 7 is a diagram showing pass characteristics of the acoustic wave filter devices of Example 3 and Comparative Examples 2 and 3.
  • FIG. 8 is a circuit configuration diagram of a multiplexer and its peripheral circuits according to the second embodiment.
  • Embodiment 1 (Embodiment 1) [Schematic configuration of elastic wave filter device] A schematic configuration of an acoustic wave filter device 1 according to Embodiment 1 will be described with reference to FIG.
  • FIG. 1 is a diagram showing a circuit configuration of an elastic wave filter device 1 according to Embodiment 1.
  • FIG. 1 is a diagram showing a circuit configuration of an elastic wave filter device 1 according to Embodiment 1.
  • the acoustic wave filter device 1 includes series arm resonators S1, S2, S3, S4 and S5, parallel arm resonators P1, P2, P3 and P4, input/output terminals 50 and 60, Prepare.
  • the series arm resonators S1 to S5 are arranged in series on the first path r1 connecting the input/output terminal 50 and the input/output terminal 60.
  • the parallel arm resonators P1 to P4 are arranged on a path connecting the first path r1 and the ground (reference terminal).
  • the elastic wave filter device 1 constitutes a ladder-type bandpass filter by the connection configuration of the series arm resonators S1 to S5 and the parallel arm resonators P1 to P4.
  • the circuit configuration shown in FIG. 1 is just an example, and the number of series arm resonators, the number of parallel arm resonators, etc. are not limited to the configuration of FIG.
  • FIG. 2 is a diagram schematically showing the electrode configuration of the elastic wave resonator 10 included in the elastic wave filter device 1.
  • FIG. 2A is a plan view of the acoustic wave resonator 10
  • FIG. 2B is an enlarged cross-sectional view of the acoustic wave resonator 10 of FIG.
  • FIG. 2 is an enlarged cross-sectional view of the elastic wave resonator 10 of (a) as seen along line cc.
  • the elastic wave resonator 10 shown in FIG. 2 is formed of a piezoelectric substrate 100, an electrode 110, and a protective film 113, and an IDT (Inter Digital Transducer) electrode 11 and a first A reflector 31 and a second reflector 32 are provided.
  • the acoustic wave resonator 10 according to the present embodiment is a surface acoustic wave (SAW) resonator composed of an IDT electrode 11, a first reflector 31, a second reflector 32, and a piezoelectric substrate 100. be.
  • SAW surface acoustic wave
  • the acoustic wave resonator 10 shown in FIG. 2 is for describing its typical structure, and the number and length of the electrode fingers constituting the electrodes are not limited to this.
  • the electrode 110 constituting the IDT electrode 11, the first reflector 31 and the second reflector 32 has a laminate structure of an adhesion layer 111 and a main electrode layer 112, as shown in FIGS. It's becoming
  • the adhesion layer 111 is a layer for improving adhesion between the main surface 100a of the piezoelectric substrate 100 and the main electrode layer 112, and is made of Ti, for example.
  • the material of the main electrode layer 112 is, for example, Al containing 1% Cu.
  • the protective film 113 is formed to cover electrode 110 .
  • the protective film 113 is a layer for the purpose of protecting the main electrode layer 112 from the external environment, adjusting frequency temperature characteristics, and increasing moisture resistance . It is a membrane that
  • the materials forming the adhesion layer 111, the main electrode layer 112, and the protective film 113 are not limited to the materials described above. Furthermore, the electrode 110 does not have to have the laminated structure described above.
  • the electrode 110 may be composed of metals or alloys such as Ti, Al, Cu, Pt, Au, Ag, and Pd, for example, and may be composed of a plurality of laminates composed of the above metals or alloys. good too. Also, the protective film 113 may not be formed.
  • the piezoelectric substrate 100 is, for example, a ⁇ ° Y-cut X-propagating LiNbO 3 piezoelectric single crystal or piezoelectric ceramic (cut along a plane normal to an axis rotated ⁇ ° from the Y-axis in the Z-axis direction with the X-axis as the central axis). Lithium niobate single crystal or ceramics, which allows surface acoustic waves to propagate in the X-axis direction).
  • the piezoelectric substrate 100 may be a substrate having a piezoelectric layer at least partially, or may have a laminated structure having a piezoelectric layer.
  • the piezoelectric substrate 100 includes, for example, a high acoustic velocity supporting substrate, a low acoustic velocity film, and a piezoelectric layer, and has a structure in which the high acoustic velocity supporting substrate, low acoustic velocity film, and piezoelectric layer are laminated in this order.
  • the IDT electrode 11 is formed on the piezoelectric substrate 100 and has a pair of comb electrodes 11A and 11B facing each other.
  • the pair of comb-shaped electrodes 11A and 11B has comb-shaped electrode fingers 11a and 11b extending in the first direction d1 parallel to the main surface 100a of the piezoelectric substrate 100.
  • the direction in which the comb-teeth electrode fingers 11a and 11b extend is defined as a first direction d1
  • the direction parallel to the main surface 100a of the piezoelectric substrate 100 and crossing the first direction d1 is defined as a second direction d2.
  • the second direction d2 in the present embodiment is the same direction as the elastic wave propagation direction in the IDT.
  • the first direction d1 and the second direction d2 in the present embodiment are orthogonal.
  • the comb-shaped electrode 11A includes a plurality of comb-shaped electrode fingers 11a extending in the first direction d1 and arranged along the second direction d2, and bus bar electrodes 11c connecting one ends of the plurality of comb-shaped electrode fingers 11a. ,have.
  • the comb-shaped electrode 11B includes a plurality of comb-shaped electrode fingers 11b extending in the first direction d1 and arranged along the second direction d2, and bus bar electrodes 11c connecting one ends of the plurality of comb-shaped electrode fingers 11b. ,have.
  • the plurality of comb-teeth electrode fingers 11a and 11b are arranged alternately along the second direction d2.
  • Each of the first reflector 31 and the second reflector 32 is arranged adjacent to the IDT electrode 11 in the second direction d2. Specifically, the first reflector 31 is arranged next to the IDT electrode 11 in the second direction d2. The second reflector 32 is arranged next to the IDT electrode 11 in the second direction d2 and on the opposite side of the first reflector 31 when viewed from the IDT electrode 11 . That is, the first reflector 31 and the second reflector 32 are arranged on both sides of the IDT electrode 11 in the second direction d2.
  • the first reflector 31 includes a plurality of first reflecting electrode fingers 31a extending in the first direction d1 and arranged along the second direction d2, and a plurality of first reflecting electrode fingers extending along the second direction d2. and two busbar electrodes 31c connecting one ends of the busbar electrodes 31a.
  • the second reflector 32 includes a plurality of second reflective electrode fingers 32a extending in the first direction d1 and arranged along the second direction d2, and a plurality of second reflective electrode fingers 32a extending along the second direction d2. It has two busbar electrodes 32c connecting one ends of the busbar electrodes 32a.
  • the IDT wavelength ⁇ i is defined as twice the arrangement pitch pi of the plurality of comb-tooth electrode fingers 11a and 11b included in the pair of comb-shaped electrodes 11A and 11B.
  • a pitch twice the arrangement pitch pr1 of the plurality of first reflective electrode fingers 31a is defined as the first reflector wavelength ⁇ r1
  • a pitch twice the arrangement pitch pr2 of the plurality of second reflective electrode fingers 32a is defined as ⁇ r1.
  • the acoustic wave resonator 10 in the present embodiment is configured such that the first reflector wavelength ⁇ r1 is larger than the second reflector wavelength ⁇ r2. According to this configuration, it is possible to improve the flatness of the passband of the elastic wave filter device 1 .
  • the arrangement pitch pi of the comb-toothed electrode fingers 11a and 11b is the center of the comb-toothed electrode fingers 11a and 11b adjacent to each other in the second direction d2 in the plurality of comb-toothed electrode fingers 11a and 11b included in the IDT electrode 11.
  • the distance between the centers in the second direction d2 between the two electrode fingers may be simply referred to as the "center-to-center distance"
  • All the arrangement pitches of the plurality of comb-teeth electrode fingers 11a and 11b in the IDT electrode 11 may be the same, or some or all of the arrangement pitches may be different.
  • the array pitch pi can be derived as follows.
  • the total number of comb-teeth electrode fingers 11a and 11b included in the IDT electrode 11 is assumed to be Ni.
  • Di is the center-to-center distance between the comb electrode finger positioned at one end of the IDT electrode 11 and the comb electrode finger positioned at the other end in the second direction d2.
  • the arrangement pitch pr1 of the first reflective electrode fingers 31a is the center-to-center distance between the first reflective electrode fingers 31a adjacent to each other in the second direction d2. All the arrangement pitches of the plurality of first reflective electrode fingers 31a in the first reflector 31 may be the same, or some or all of the arrangement pitches may be different.
  • the arrangement pitch pr2 of the second reflective electrode fingers 32a is the center-to-center distance between the second reflective electrode fingers 32a adjacent to each other in the second direction d2. All the arrangement pitches of the plurality of second reflective electrode fingers 32a in the second reflector 32 may be the same, or some or all of the arrangement pitches may be different.
  • the array pitch pr2 can also be derived in the same manner as the array pitch pr1.
  • the comb-teeth electrode finger (11a in FIG. 2) closest to the first reflector 31 A center-to-center distance in the second direction d2 between the first reflecting electrode finger 31a closest to the IDT electrode 11 among the plurality of first reflecting electrode fingers 31a is defined as a first IDT-reflector gap g1.
  • the comb-teeth electrode finger (11a in FIG. 2) closest to the second reflector 32 A second IDT-reflector gap g2 is defined as the center-to-center distance between the second reflective electrode finger 32a closest to the IDT electrode 11 and the second reflective electrode finger 32a.
  • the acoustic wave resonator 10 of the present embodiment is configured such that the first IDT-reflector gap g1 has a different value from the second IDT-reflector gap g2.
  • the first IDT-reflector gap g1 is configured to be smaller or larger than the second IDT-reflector gap g2.
  • FIG. 3 is a diagram showing reflector wavelengths, IDT-reflector gaps, return losses, etc. of elastic wave resonators of Comparative Example 1 and Examples 1 and 2.
  • FIG. 3 is a diagram showing reflector wavelengths, IDT-reflector gaps, return losses, etc. of elastic wave resonators of Comparative Example 1 and Examples 1 and 2.
  • the values of the first reflector wavelength ⁇ r1, the second reflector wavelength ⁇ r2, the first IDT-reflector gap g1, and the second IDT-reflector gap g2 of the elastic wave resonator are It is shown.
  • the figure also shows the first reflector wavelength ratio ⁇ r1/ ⁇ i, which is the value obtained by dividing the first reflector wavelength ⁇ r1 by the IDT wavelength ⁇ i, and the second reflector wavelength ⁇ r2 by the IDT wavelength ⁇ i.
  • the divided value, the second reflector wavelength ratio ⁇ r2/ ⁇ i is shown.
  • the figure also shows a first gap wavelength ratio g1/ ⁇ r1, which is a value obtained by dividing the first IDT-reflector gap g1 by the first reflector wavelength ⁇ r1, and the second IDT-reflector gap g1/ ⁇ r1.
  • a second gap wavelength ratio g2/ ⁇ r2 is shown, which is the gap g2 divided by the second reflector wavelength ⁇ r2.
  • the first reflector wavelength ⁇ r1 is larger than the second reflector wavelength ⁇ r2 ( ⁇ r1> ⁇ r2), and the first IDT-reflector
  • the first reflector wavelength ⁇ r1 is larger than the second reflector wavelength ⁇ r2 ( ⁇ r1> ⁇ r2), and the first IDT-reflector gap g1 is It has a configuration that is smaller than the second IDT-reflector gap g2 (g1 ⁇ g2).
  • the first reflector wavelength ratio ⁇ r1/ ⁇ i is greater than the second reflector wavelength ratio ⁇ r2/ ⁇ i.
  • the first gap wavelength ratio g1/ ⁇ r1 is smaller than the second gap wavelength ratio g2/ ⁇ r2.
  • the first reflector wavelength ⁇ r1 is larger than the second reflector wavelength ⁇ r2 ( ⁇ r1> ⁇ r2), and the first IDT-reflector gap g1 is 2 IDT-reflector gap g2 (g1>g2).
  • the first reflector wavelength ratio ⁇ r1/ ⁇ i is greater than the second reflector wavelength ratio ⁇ r2/ ⁇ i.
  • the first gap wavelength ratio g1/ ⁇ r1 is larger than the second gap wavelength ratio g2/ ⁇ r2.
  • FIG. 4 is a diagram showing return losses of elastic wave resonators of Comparative Example 1 and Examples 1 and 2.
  • Example 1 unnecessary responses are suppressed in the vicinity of 2496 MHz, which is the lowest frequency of the passband.
  • the largest return loss value near 2496 MHz is 0.140 dB (see FIG. 3), which is smaller than that of Comparative Example 1.
  • generation of unnecessary response is suppressed in the vicinity of 2690 MHz, which is the highest frequency of the passband.
  • the largest return loss value near 2690 MHz is 0.325 dB (see FIG. 3), which is smaller than Comparative Example 1 and Example 2 described later.
  • Example 2 generation of unnecessary responses is suppressed near 2496 MHz, which is the lowest frequency of the passband.
  • the largest return loss value in the vicinity of 2496 MHz is 0.134 dB (see FIG. 3), which is smaller than Comparative Example 1 and Example 1.
  • generation of an unnecessary response is suppressed in the vicinity of 2690 MHz, which is the highest frequency of the passband.
  • the largest return loss value near 2690 MHz is 0.344 dB (see FIG. 3), which is smaller than that of Comparative Example 1.
  • the elastic wave resonators 10 of Examples 1 and 2 are configured such that the first IDT-reflector gap g1 has a different value from the second IDT-reflector gap g2.
  • the first IDT-reflector gap g1 is configured to have a smaller value than the second IDT-reflector gap g2. According to this configuration, it is possible to suppress the occurrence of unnecessary responses at the lowest and highest frequencies of the passband of the acoustic wave filter device 1 . In particular, by making the first IDT-reflector gap g1 smaller than the second IDT-reflector gap g2, it is possible to suppress the occurrence of unnecessary response at the highest frequency of the passband.
  • the first IDT-reflector gap g1 is configured to have a larger value than the second IDT-reflector gap g2. According to this configuration, it is possible to suppress the occurrence of unnecessary responses at the lowest and highest frequencies of the passband of the acoustic wave filter device 1 . In particular, by making the first IDT-reflector gap g1 larger than the second IDT-reflector gap g2, it is possible to suppress the occurrence of unnecessary response at the lowest frequency of the passband.
  • FIG. 5 is a diagram showing electrode parameters and the like of the series arm resonators S1 to S5 and the parallel arm resonators P1 to P4 included in the acoustic wave filter device 1 of the third embodiment. Note that the series arm resonators and parallel arm resonators shown in FIG. It may be applied to the arm resonator and at least one parallel arm resonator.
  • the figure shows the logarithm of the IDT electrode 11, the logarithm of the first reflector 31, the logarithm of the second reflector 32, the intersection width of the IDT electrode 11, and the IDT wavelength ⁇ i for each of the series arm resonator and the parallel arm resonator.
  • a first reflector wavelength ⁇ r1 and a second reflector wavelength ⁇ r2 are shown.
  • the figure also shows the first reflector wavelength ratio ⁇ r1/ ⁇ i and the second reflector wavelength ratio ⁇ r2/ ⁇ i for each of the series arm resonator and the parallel arm resonator.
  • the figure also shows, for each of the series arm resonator and the parallel arm resonator, a first IDT-reflector gap g1, a second IDT-reflector gap g2, a first gap wavelength ratio g1/ ⁇ r1 and A second gap wavelength ratio g2/ ⁇ r2 is shown.
  • the difference between the first reflector wavelength ratio ⁇ r1/ ⁇ i and the second reflector wavelength ratio ⁇ r2/ ⁇ i in the series arm resonator is It is configured to be greater than the difference between the first reflector wavelength ratio ⁇ r1/ ⁇ i and the second reflector wavelength ratio ⁇ r2/ ⁇ i. According to this configuration, it is possible to suppress an increase in insertion loss at the lowest and highest frequencies of the passband of the acoustic wave filter device 1 . Thereby, it is possible to suppress deterioration of the pass characteristic of the acoustic wave filter device 1 .
  • the first IDT-reflector gap g1 in the series arm resonator is smaller than the first IDT-reflector gap g1 in the parallel arm resonator.
  • the second IDT-reflector gap g2 in the series arm resonator is smaller than the second IDT-reflector gap g2 in the parallel arm resonator.
  • FIG. 6 is a diagram showing reflector wavelengths, IDT-reflector gaps, etc. of series arm resonators and parallel arm resonators included in acoustic wave filter devices of Example 3 and Comparative Examples 2 and 3.
  • FIG. 6 also shows the insertion loss of the acoustic wave filter device.
  • the difference between the first reflector wavelength ratio ⁇ r1/ ⁇ i and the second reflector wavelength ratio ⁇ r2/ ⁇ i is the same as the series arm resonator and parallel It is configured differently from the arm resonator. Specifically, the difference ( ⁇ r1/ ⁇ i ⁇ r2/ ⁇ i) between the first reflector wavelength ratio and the second reflector wavelength ratio in the series arm resonator is 0.02, and the second reflector wavelength ratio in the parallel arm resonator is 0.02.
  • the difference ( ⁇ r1/ ⁇ i ⁇ r2/ ⁇ i) between the first reflector wavelength ratio and the second reflector wavelength ratio is 0.005, and the difference between the first reflector wavelength ratio and the second reflector wavelength ratio is The difference is configured to be greater in the series arm resonator than in the parallel arm resonator.
  • the first IDT-reflector gap g1 in the series arm resonator is the first IDT-reflector gap g1 in the parallel arm resonator. is configured to be smaller than Further, in the acoustic wave filter device 1, the second IDT-reflector gap g2 in the series arm resonator is configured to be smaller than the second IDT-reflector gap g2 in the parallel arm resonator.
  • the difference between the first reflector wavelength ratio ⁇ r1/ ⁇ i and the second reflector wavelength ratio ⁇ r2/ ⁇ i is configured to have the same value.
  • the first reflector wavelength ratio and the second reflector wavelength ratio in the series arm resonator are configured to be the same value, and the first reflector wavelength ratio in the parallel arm resonator and the second reflector wavelength ratio have the same value.
  • the difference ( ⁇ r1/ ⁇ i ⁇ r2/ ⁇ i) between the first reflector wavelength ratio and the second reflector wavelength ratio in the series arm resonator becomes 0, and the first reflector wavelength in the parallel arm resonator becomes
  • the difference ( ⁇ r1/ ⁇ i ⁇ r2/ ⁇ i) between the ratio and the second reflector wavelength ratio is 0, and the difference between the first reflector wavelength ratio and the second reflector wavelength ratio is the series arm resonator and It has the same value as the parallel arm resonator.
  • FIG. 7 is a diagram showing pass characteristics of the elastic wave filter devices of Example 3 and Comparative Examples 2 and 3.
  • FIG. As described above, the pass band of the elastic wave filter device 1 is 2496 MHz to 2690 MHz.
  • the frequency at which an unwanted response can occur overlaps with the high frequency of the low passband and the highest frequency.
  • Comparative Example 3 an insertion loss of 1.26 dB occurs at 2496 MHz, which is the lowest frequency of the passband (see FIG. 6).
  • the insertion loss at the lowest frequency of the passband is 1.23 dB (see FIG. 6), which is smaller than that in Comparative Example 3.
  • the elastic wave filter device 1 of the third embodiment it is possible to suppress an increase in insertion loss at both the lowest frequency and the highest frequency of the passband. Thereby, it is possible to suppress deterioration of the pass characteristic of the acoustic wave filter device 1 .
  • FIG. 8 is a circuit configuration diagram of the multiplexer 5 and its peripheral circuit (antenna 4) according to the second embodiment.
  • the multiplexer 5 shown in the figure includes an elastic wave filter device 1, another filter 3 different from the elastic wave filter device 1, a common terminal 70, and input/output terminals 81 and 82.
  • FIG. 8 is a circuit configuration diagram of the multiplexer 5 and its peripheral circuit (antenna 4) according to the second embodiment.
  • the multiplexer 5 shown in the figure includes an elastic wave filter device 1, another filter 3 different from the elastic wave filter device 1, a common terminal 70, and input/output terminals 81 and 82.
  • the elastic wave filter device 1 is the elastic wave filter device 1 according to Embodiment 1.
  • the input/output terminal 50 of the elastic wave filter device 1 is connected to the input/output terminal 81, and the input/output terminal of the elastic wave filter device 1 is connected to the input/output terminal 81.
  • 60 is connected to common terminal 70 .
  • the other filters 3 are connected to the common terminal 70 and the input/output terminal 82 .
  • the other filter 3 is, for example, a ladder-type elastic wave filter device having parallel arm resonators and series arm resonators, but may be an LC filter or the like, and its circuit configuration is not particularly limited.
  • the multiplexer 5 includes a plurality of filters including the acoustic wave filter device 1, and one of the input/output terminals 81 and 82 of each of the plurality of filters is directly or indirectly connected to the common terminal 70.
  • the multiplexer 5 including the acoustic wave filter device 1 capable of suppressing deterioration of the pass characteristic.
  • the passband of the elastic wave filter device 1 may be located on the high frequency side of the passbands of the other filters 3 . That is, at least one of the filters 3 other than the elastic wave filter device 1 may have a passband lower than the frequency of the passband of the elastic wave filter device 1 .
  • the elastic wave resonator arranged closest to the common terminal 70 on the first path r1 has a first reflector wavelength higher than the second reflector wavelength. is larger and the first IDT-reflector gap is smaller than the second IDT-reflector gap.
  • the passband of the elastic wave filter device 1 may be located on the lower frequency side than the passbands of the other filters 3 . That is, at least one of the filters 3 other than the elastic wave filter device 1 among the plurality of filters may have a passband higher than the frequency of the passband of the elastic wave filter device 1 .
  • the elastic wave resonator arranged closest to the common terminal 70 on the first path r1 has a first reflector wavelength higher than the second reflector wavelength. is larger and the first IDT-reflector gap is smaller than the second IDT-reflector gap.
  • the acoustic wave filter device 1 and other filters 3 may not be directly connected to the common terminal 70 as shown in FIG. It may be indirectly connected to the common terminal 70 via a filter-selectable switch element.
  • multiplexer 5 has a circuit configuration in which two filters are connected to common terminal 70, but the number of filters connected to common terminal 70 is not limited to two, and may be three or more. There may be.
  • Elastic wave resonator 10 is formed on piezoelectric substrate 100 and has a plurality of comb-teeth electrode fingers 11a and 11b extending in first direction d1 parallel to main surface 100a of piezoelectric substrate 100.
  • a second reflector 32 arranged next to the IDT electrode 11 and on the opposite side of the first reflector 31 when viewed from the IDT electrode 11 .
  • the IDT electrode 11 has a pair of comb-shaped electrodes 11A and 11B.
  • the pair of comb-shaped electrodes 11A and 11B has a plurality of comb-shaped electrode fingers 11a extending in the first direction d1 and arranged along the second direction d2. 11b, and a bus bar electrode 11c connecting one ends of each of the plurality of comb-teeth electrode fingers 11a and 11b.
  • the first reflector 31 extends in the first direction d1 and has a plurality of first reflective electrode fingers 31a arranged along the second direction d2
  • the second reflector 32 extends in the first direction d1 and has It has a plurality of second reflective electrode fingers 32a arranged along the second direction d2.
  • the first reflector wavelength ⁇ r1 which is twice the arrangement pitch pr1 of the plurality of first reflective electrode fingers 31a arranged along the second direction d2, is obtained by the plurality of second reflector wavelengths ⁇ r1 arranged along the second direction d2. It is larger than the second reflector wavelength ⁇ r2 which is twice the arrangement pitch pr2 of the reflective electrode fingers 32a ( ⁇ r1> ⁇ r2).
  • the center of the comb electrode finger closest to the first reflector 31 among the plurality of comb electrode fingers 11a and 11b and the center of the first reflective electrode finger 31a closest to the IDT electrode 11 among the plurality of first reflective electrode fingers 31a The first IDT-reflector gap g1, which is the distance between the center of the comb-shaped electrode finger closest to the second reflector 32 among the plurality of comb-shaped electrode fingers 11a and 11b, and the plurality of second reflective electrode fingers 32a It is smaller than the second IDT-reflector gap g2, which is the distance from the center of the second reflective electrode finger 32a closest to the IDT electrode 11 (g1 ⁇ g2).
  • the elastic wave filter device 1 includes a plurality of elastic wave resonators 10 described above.
  • the plurality of elastic wave resonators 10 includes one or more series arm resonators S1 to S5 arranged on a first path r1 connecting two input/output terminals 50 and 60, a node on the first path r1, and a ground. and one or more parallel arm resonators P1 to P4 arranged on a path connecting the .
  • the first reflector wavelength ⁇ r1 is set to the arrangement pitch of the plurality of comb electrode fingers 11a and 11b of the pair of comb electrodes 11A and 11B.
  • the difference between the value ( ⁇ r1/ ⁇ i) divided by the IDT wavelength ⁇ i which is twice pi and the value ( ⁇ r2/ ⁇ i) obtained by dividing the second reflector wavelength ⁇ r2 by the IDT wavelength ⁇ i is equal to or greater than 1 parallel
  • the first reflector wavelength ⁇ r1 is twice the arrangement pitch pi of the plurality of comb electrode fingers 11a and 11b of the pair of comb electrodes 11A and 11B.
  • the difference between the first reflector wavelength ratio ( ⁇ r1/ ⁇ i) and the second reflector wavelength ratio ( ⁇ r2/ ⁇ i) is greater in the series arm resonator than in the parallel arm resonator. . According to this, it is possible to suppress an increase in insertion loss at the lowest frequency and the highest frequency of the passband of the elastic wave filter device 1 . Thereby, it is possible to suppress deterioration of the pass characteristic of the elastic wave filter device 1 .
  • first IDT-reflector gap g1 in the at least one series arm resonator is smaller than the first IDT-reflector gap g1 in the at least one parallel arm resonator, and the at least one series arm
  • the second IDT-reflector gap g2 in the resonator may be smaller than the second IDT-reflector gap g2 in the at least one parallel arm resonator.
  • the first reflector wavelength ⁇ r1 is set to the arrangement pitch pi of the plurality of comb electrode fingers 11a and 11b of the pair of comb electrodes 11A and 11B.
  • the difference between the value ( ⁇ r/ ⁇ i) divided by the IDT wavelength ⁇ i which is twice the value of the second reflector wavelength ⁇ r2 divided by the IDT wavelength ⁇ i ( ⁇ r2/ ⁇ i) is equal to or greater than one parallel arm
  • the first reflector wavelength ⁇ r1 is the IDT wavelength that is twice the arrangement pitch pi of the plurality of comb-teeth electrode fingers 11a and 11b of the pair of comb-teeth electrodes 11A and 11B. It may be greater than the difference between ( ⁇ r1/ ⁇ i) divided by ⁇ i and ( ⁇ r2/ ⁇ i) the second reflector wavelength ⁇ r2 divided by the IDT wavelength ⁇ i.
  • the first IDT-reflector gap g1 in all the series arm resonators is smaller than the first IDT-reflector gap g1 in all the parallel arm resonators, and the second IDT-reflector gap g1 in all the series arm resonators
  • the IDT-reflector gap g2 may be smaller than the second IDT-reflector gap g2 in all parallel arm resonators.
  • a multiplexer 5 includes a plurality of filters including the acoustic wave filter device 1 described above, and one input/output terminal of each of the plurality of filters is directly or indirectly connected to a common terminal.
  • the multiplexer 5 including the acoustic wave filter device 1 capable of suppressing deterioration of the pass characteristic.
  • Elastic wave resonator 10 is formed on piezoelectric substrate 100 and has a plurality of comb-teeth electrode fingers 11a and 11b extending in first direction d1 parallel to main surface 100a of piezoelectric substrate 100.
  • a second reflector 32 arranged next to the IDT electrode 11 and on the opposite side of the first reflector 31 when viewed from the IDT electrode 11 .
  • the IDT electrode 11 has a pair of comb-shaped electrodes 11A and 11B.
  • the pair of comb-shaped electrodes 11A and 11B has a plurality of comb-shaped electrode fingers 11a extending in the first direction d1 and arranged along the second direction d2. 11b, and a bus bar electrode 11c connecting one ends of each of the plurality of comb-teeth electrode fingers 11a and 11b.
  • the first reflector 31 extends in the first direction d1 and has a plurality of first reflective electrode fingers 31a arranged along the second direction d2
  • the second reflector 32 extends in the first direction d1 and has It has a plurality of second reflective electrode fingers 32a arranged along the second direction d2.
  • the first reflector wavelength ⁇ r1 which is twice the arrangement pitch pr1 of the plurality of first reflective electrode fingers 31a arranged along the second direction d2, is obtained by the plurality of second reflector wavelengths ⁇ r1 arranged along the second direction d2. It is larger than the second reflector wavelength ⁇ r2 which is twice the arrangement pitch pr2 of the reflective electrode fingers 32a ( ⁇ r1> ⁇ r2).
  • the center of the comb electrode finger closest to the first reflector 31 among the plurality of comb electrode fingers 11a and 11b and the center of the first reflective electrode finger 31a closest to the IDT electrode 11 among the plurality of first reflective electrode fingers 31a The first IDT-reflector gap g1, which is the distance between the center of the comb-shaped electrode finger closest to the second reflector 32 among the plurality of comb-shaped electrode fingers 11a and 11b, and the plurality of second reflective electrode fingers 32a Among them, it is larger than the second IDT-reflector gap g2, which is the distance from the center of the second reflecting electrode finger 32a closest to the IDT electrode 11 (g1>g2).
  • the elastic wave resonator, the elastic wave filter device, and the multiplexer according to the embodiments of the present invention have been described above with reference to the embodiments and examples. is not limited to the above embodiments and examples. Other embodiments realized by combining arbitrary components in the above-described embodiments and examples, and various modifications that can be made by those skilled in the art within the scope of the present invention without departing from the scope of the above-described embodiments.
  • the present invention also includes various devices incorporating the obtained embodiments and the acoustic wave resonators, acoustic wave filter devices, and multiplexers of the present disclosure.
  • one series arm resonator among the series arm resonators S1 to S5 is taken as an example
  • one parallel arm resonator among the parallel arm resonators P1 to P4 is taken as an example. 5
  • the series arm resonators and parallel arm resonators satisfying the conditions shown in FIG. just do it.
  • the elastic wave filter device 1 may further include circuit elements such as inductors and capacitors.
  • the elastic wave resonator according to the present invention may not be a surface acoustic wave resonator as in Embodiment 1, but may be an elastic wave resonator using boundary acoustic waves.
  • the piezoelectric substrate 100 may be a substrate having a piezoelectric layer at least partially, or may have a laminated structure having a piezoelectric layer.
  • the piezoelectric substrate 100 includes, for example, a high acoustic velocity supporting substrate, a low acoustic velocity film, and a piezoelectric layer, and has a structure in which the high acoustic velocity supporting substrate, low acoustic velocity film, and piezoelectric layer are laminated in this order. may
  • the configurations of the high acoustic velocity supporting substrate, the low acoustic velocity film and the piezoelectric layer will be described below.
  • the piezoelectric layer is, for example, a ⁇ ° Y-cut X-propagation LiNbO 3 piezoelectric single crystal or piezoelectric ceramics (niobium cut along a plane normal to an axis rotated ⁇ ° from the Y-axis in the Z-axis direction with the X-axis as the central axis). It consists of a lithium oxide single crystal or ceramics in which a surface acoustic wave propagates in the X-axis direction.
  • the high acoustic velocity support substrate is a substrate that supports the low acoustic velocity film, the piezoelectric layer and the electrode 110 . Further, the high acoustic velocity support substrate is a substrate in which the sound velocity of the bulk wave in the high acoustic velocity support substrate is faster than the acoustic waves of the surface waves and the boundary waves propagating through the piezoelectric layer. And the low acoustic velocity film is confined in the laminated portion, and functions so as not to leak below the high acoustic velocity support substrate.
  • the high acoustic velocity support substrate is, for example, a silicon substrate.
  • the high sonic velocity support substrate includes (1) a piezoelectric material such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon, sapphire, lithium tantalate, lithium niobate, or quartz, and (2) alumina, zirconia, cordage.
  • a piezoelectric material such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon, sapphire, lithium tantalate, lithium niobate, or quartz
  • alumina, zirconia, cordage such as lite, mullite, steatite, or forsterite, (3) magnesia diamond, (4) materials containing the above materials as main components, and (5) materials containing mixtures of the above materials as main components , or
  • 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 the sound velocity of the elastic wave propagating through the piezoelectric layer, and is arranged between the piezoelectric layer and the high sound velocity support substrate. .
  • This structure and the nature of the elastic wave to concentrate its energy in a low-temperature medium suppresses leakage of the surface acoustic wave energy to the outside of the IDT electrode.
  • the low sound velocity film is, for example, a film whose main component is silicon dioxide (SiO 2 ).
  • the Q value of the acoustic wave resonator at the resonance frequency and the anti-resonance frequency can be significantly increased compared to the structure using the piezoelectric substrate 100 as a single layer. It becomes possible. That is, since a surface acoustic wave resonator with a high Q value can be constructed, it is possible to construct a filter with a small insertion loss using the surface acoustic wave resonator.
  • the high acoustic velocity support substrate has a structure in which a support substrate and a high acoustic velocity film are laminated such that the acoustic velocity of a bulk wave propagating through the piezoelectric layer is higher than that of an elastic wave such as a surface wave or a boundary wave.
  • the support substrate may be a piezoelectric material such as sapphire, lithium tantalate, lithium niobate, quartz crystal, etc.; Dielectrics such as various ceramics and glasses, semiconductors such as silicon and gallium nitride, and resin substrates can be used.
  • the high acoustic velocity film can be made of various materials such as aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, DLC film or diamond, media mainly composed of the above materials, and media mainly composed of mixtures of the above materials. high acoustic velocity materials can be used.
  • each layer exemplified in the above laminated structure of the piezoelectric substrate 100 is only examples, and are changed according to, for example, the characteristics to be emphasized among the required high-frequency propagation characteristics.
  • the present invention can be widely used in communication equipment such as mobile phones as a multiband and multimode low-loss acoustic wave filter device and multiplexer.

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

Abstract

La présente invention concerne un résonateur à ondes élastiques (10) qui comprend une électrode IDT (11), un premier réflecteur (31) et un deuxième réflecteur (32). L'électrode IDT (11) comporte une pluralité de doigts d'électrode à dents en peigne (11a, 11b). Le premier réflecteur (31) a une pluralité de premiers doigts d'électrode de réflexion (31a), et le deuxième réflecteur (32) a une pluralité de deuxièmes doigts d'électrode de réflexion (32a). Une première longueur d'onde de réflecteur (λr1), qui est le double du pas (pr1) dans lequel la pluralité de premiers doigts d'électrode de réflexion (31a) sont agencés, est supérieure à une deuxième longueur d'onde de réflecteur (λr2), qui est le double du pas (pr2) dans lequel la pluralité de deuxièmes doigts d'électrode de réflexion (32a) sont agencés. Un premier espace IDT-réflecteur (g1), qui est la distance entre le centre du doigt d'électrode à dents en peigne qui est le plus proche du premier réflecteur (31) et le centre du premier doigt d'électrode de réflexion qui est le plus proche de l'électrode IDT (11), est plus petit qu'un deuxième espace IDT-réflecteur (g2), qui est la distance entre le centre du doigt d'électrode à dents en peigne qui est le plus proche du deuxième réflecteur (32) et le centre du deuxième doigt d'électrode de réflexion qui est le plus proche de l'électrode IDT (11).
PCT/JP2022/038059 2021-10-29 2022-10-12 Résonateur à ondes élastiques, dispositif de filtre à ondes élastiques et multiplexeur WO2023074373A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08181565A (ja) * 1994-12-22 1996-07-12 Maruyasu Kogyo Kk 弾性表面波変換器
JPH10215144A (ja) * 1997-01-31 1998-08-11 Oki Electric Ind Co Ltd 弾性表面波共振子及び弾性表面波装置
JPH10215145A (ja) * 1997-01-30 1998-08-11 Fujitsu Ltd 弾性表面波共振器及びラダー型弾性表面波フィルタ
WO2019177028A1 (fr) * 2018-03-14 2019-09-19 株式会社村田製作所 Dispositif à ondes élastiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08181565A (ja) * 1994-12-22 1996-07-12 Maruyasu Kogyo Kk 弾性表面波変換器
JPH10215145A (ja) * 1997-01-30 1998-08-11 Fujitsu Ltd 弾性表面波共振器及びラダー型弾性表面波フィルタ
JPH10215144A (ja) * 1997-01-31 1998-08-11 Oki Electric Ind Co Ltd 弾性表面波共振子及び弾性表面波装置
WO2019177028A1 (fr) * 2018-03-14 2019-09-19 株式会社村田製作所 Dispositif à ondes élastiques

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