Filter and multiplexer

Patent metadata

Field	Value
Publication number	US-12255602-B2
Application number	US-202217864927-A
Country	US
Kind code	B2
Filing date	Jul 14, 2022
Priority date	Jul 27, 2021
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

A filter includes a series resonator including a first piezoelectric layer and first electrodes, and a parallel resonator including a second piezoelectric layer and second electrodes. Each of the first and second piezoelectric layers is a monocrystalline lithium niobate layers, has an X-axis orientation in a planar direction, and has a thickness direction in a direction obtained by a 105° rotation of a +Z-axis orientation toward a +Y-axis orientation. The first electrodes face each other across the first piezoelectric layer to form a first resonance region and are extracted from the first resonance region in a direction substantially parallel to the X-axis orientation of the first piezoelectric layer. The second electrodes face each other across the second piezoelectric layer to form a second resonance region and are extracted from the second resonance region in a direction substantially orthogonal to the X-axis orientation of the second piezoelectric layer.

First claim

What is claimed is:

1. A filter comprising:
a substrate;
a series resonator that is disposed on the substrate, is connected in series between an input terminal and an output terminal, and includes a first piezoelectric layer and a pair of first electrodes, the first piezoelectric layer being a monocrystalline lithium niobate layer or a monocrystalline lithium tantalate layer, an X-axis orientation of crystal orientations of the first piezoelectric layer corresponding to a planar direction, a thickness direction of the first piezoelectric layer corresponding to a direction obtained by rotating a +Z-axis orientation of the crystal orientations of the first piezoelectric layer substantially 105° toward the +Y-axis orientation, the pair of first electrodes being opposite to each other across the first piezoelectric layer to form a first resonance region, each of the pair of first electrodes being extracted from the first resonance region in a direction that is substantially parallel to the X-axis orientation of the crystal orientations of the first piezoelectric layer; and
a parallel resonator that is disposed on the substrate, is connected in parallel between the input terminal and the output terminal, and includes a second piezoelectric layer and a pair of second electrodes, the second piezoelectric layer being a monocrystalline lithium niobate layer or a monocrystalline lithium tantalate layer, an X-axis orientation of crystal orientations of the second piezoelectric layer corresponding to a planar direction, a thickness direction of the second piezoelectric layer corresponding to a direction obtained by rotating a +Z-axis orientation of the crystal orientations of the second piezoelectric layer substantially 105° toward a +Y-axis orientation of the crystal orientations of the second piezoelectric layer, the pair of second electrodes being opposite to each other across the second piezoelectric layer to form a second resonance region, each of the pair of second electrodes being extracted from the second resonance region in a direction that is substantially orthogonal to the X-axis orientation of the crystal orientations of the second piezoelectric layer.

2. The filter according to claim 1 ,
wherein each of the pair of first electrodes is linearly extracted from the first resonance region in said direction by a length equal to or greater than 0.75 times a thickness of the first piezoelectric layer in the first resonance region, and
wherein each of the pair of second electrodes is linearly extracted from the second resonance region in said direction by a length equal to or greater than 0.75 times a thickness of the second piezoelectric layer in the second resonance region.

3. The filter according to claim 2 , further comprising:
a first wiring line coupled to an end opposite from the first resonance region of one of the pair of first electrodes; and
a second wiring line coupled to an end opposite from the second resonance region of one of the pair of second electrodes,
wherein a width of the first wiring line varies with distance from the one of the pair of first electrodes and/or a width of the second wiring line varies with distance from the one of the pair of second electrodes.

4. The filter according to claim 3 ,
wherein the series resonator is provided in a plurality, connected in series between the input terminal and the output terminal by a plurality of the first wiring lines, and the plurality of the series resonators are arranged such that the crystal orientations of the first piezoelectric layers of the plurality of the series resonator are the same,
wherein the plurality of series resonators are arranged side by side substantially in parallel with a direction parallel to the X-axis orientation of the crystal orientations of the first piezoelectric layer, and
wherein a first series resonator of the plurality of series resonators is coupled to the input terminal by one of the plurality of first wiring lines a width of which increases with distance from the one of the pair of first electrodes to which the first wiring line is coupled, and a last series resonator of the plurality of series resonators is coupled to the output terminal by another one of the plurality of first wiring lines a width of which increases with distance from the one of the pair of first electrodes to which the first wiring line is coupled.

5. The filter according to claim 3 , wherein the parallel resonator is coupled to the first wiring line by the second wiring line a width of which decreases with distance from the pair of second electrodes.

6. The filter according to claim 2 , further comprising:
a first wiring line coupled to an end opposite from the first resonance region of one of the pair of first electrodes; and
a second wiring line coupled to an end opposite from the second resonance region of one of the pair of second electrodes,
wherein the first wiring line extends from the one of the pair of first electrodes in a direction intersecting with the direction in which the one of the pair of first electrodes is extracted from the first resonance region, and/or the second wiring line extends from the one of the pair of second electrodes in a direction intersecting with the direction in which the one of the pair of second electrodes is extracted from the second resonance region.

7. The filter according to claim 6 ,
wherein the series resonator is provided in a plurality, connected in series between the input terminal and the output terminal by a plurality of the first wiring lines, and the plurality of the series resonators are arranged such that the crystal orientations of the first piezoelectric layers of the plurality of the series resonator are the same,
wherein the plurality of series resonators are arranged side by side substantially in parallel with a direction orthogonal to the X-axis orientation of the crystal orientations of the first piezoelectric layer,
wherein a first series resonator of the plurality of series resonators is coupled to the input terminal by one of the plurality of the first wiring line that extends from the one of the pair of first electrodes in a direction intersecting with the direction in which the one of the pair of first electrodes is extracted from the first resonance region in the first series resonator, and a last series resonator of the series resonators is coupled to the output terminal by another one of the plurality of the first wiring line that extends from the one of the pair of first electrodes in a direction intersecting with the direction in which the one of the pair of first electrodes is extracted from the first resonance region in the last series resonator, and
wherein the parallel resonator is coupled to a ground terminal by the second wiring line that extends from the one of the pair of second electrodes in a direction intersecting with the direction in which the one of the pair of second electrodes is extracted from the second resonance region.

8. The filter according to claim 1 , wherein the first piezoelectric layer and the second piezoelectric layer are formed of a single continuous piezoelectric layer.

9. A multiplexer comprising:
the filter according to claim 1 .

10. A filter comprising:
a substrate;
a series resonator that is disposed on the substrate, is connected in series between an input terminal and an output terminal, and includes a first piezoelectric layer and a pair of first electrodes, the first piezoelectric layer being a monocrystalline lithium tantalate layer, an X-axis orientation of crystal orientations of the first piezoelectric layer corresponding to a thickness direction of the first piezoelectric layer, a Y-axis orientation and a Z-axis orientati

Assignees

• Taiyo Yuden Kk

Inventors

• Ishida Mamoru

Classifications

• H03H9/568

  consisting of a ladder configuration · CPC title

• H03H9/703

  Networks using bulk acoustic wave devices · CPC title

• H03H9/13

  for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) · CPC title

• H03H9/17

  having a single resonator (crystal tuning forks H03H9/21) · CPC title

• H03H9/02062

  Details relating to the vibration mode · CPC title