Acoustic wave device

An acoustic wave device comprising:

• a piezoelectric layer made of lithium niobate;
• a first comb-shaped electrode on the piezoelectric layer, including a first busbar and a plurality of first electrode fingers each including one end connected to the first busbar, and being connected to an input potential;
• a second comb-shaped electrode on the piezoelectric layer, including a second busbar and a plurality of second electrode fingers each including one end connected to the second busbar and being interdigitated with the plurality of first electrode fingers, and being connected to an output potential;
• and
• a reference potential electrode connected to a reference potential and including a plurality of third electrode fingers on the piezoelectric layer and aligned with the first electrode fingers and the second electrode fingers in a direction in which the first electrode fingers and the second electrode fingers are arranged, and a connection electrode connecting adjacent third electrode fingers;
• wherein
• an order in which a first electrode finger, a second electrode finger, and a third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger define one period;
• a direction in which the first electrode fingers, the second electrode fingers, and the third electrode fingers extend is an electrode finger extending direction, and a region where the first electrode fingers and the second electrode fingers overlap each other when viewed from a direction orthogonal or substantially orthogonal to the electrode finger extending direction is an intersection region;
• and
• Ap/px≥about 5, where Ap is an intersection width of the intersection region along the electrode finger extending direction and px is a center-to-center distance between adjacent first and third electrode fingers or a center-to-center distance between adjacent second and third electrode fingers.

An acoustic wave device comprising:

• a piezoelectric layer made of lithium niobate with Euler angles (φ, θ, ψ) within a range of Expression (1), Expression (2), or Expression (3):
• (within a range of 0°±10°, 0° to 25°, any ψ) Expression (1);
• (within a range of 0°±10°, 25° to 100°, 0° to 75° [(1-(θ-50)2/2500)]1/2 or 180°-75° [(1−(θ-50)2/2500)]1/2 to 180°) Expression (2);
• and
• (within a range of 0°±10°, 180°-40° [(1−(ψ-90)2/8100)]1/2 to 180°, any ψ) Expression (3);
• a first comb-shaped electrode on the piezoelectric layer, including a first busbar and a plurality of first electrode fingers each including one end connected to the first busbar, and being connected to an input potential;
• a second comb-shaped electrode on the piezoelectric layer, including a second busbar and a plurality of second electrode fingers each including one end connected to the second busbar and being interdigitated with the plurality of first electrode fingers, and being connected to an output potential;
• and
• a reference potential electrode connected to a reference potential and including a plurality of third electrode fingers on the piezoelectric layer and aligned with the first electrode fingers and the second electrode fingers in a direction in which the first electrode fingers and the second electrode fingers are arranged, and a connection electrode connecting adjacent third electrode fingers;
• wherein
• an order in which a first electrode finger, a second electrode finger, and a third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger define one period;
• when a direction in which the first electrode fingers, the second electrode fingers, and the third electrode fingers extend is an electrode finger extending direction, leading ends of the plurality of first electrode fingers and the plurality of second electrode fingers each face an electrode connected to one of the input potential, the output potential, and the reference potential, which is different from that of the electrode fingers, across a gap in the electrode finger extending direction;
• and
• G/px≤about 0.5, where G is a gap length of each gap along the electrode finger extending direction and px is a center-to-center distance between adjacent first and third electrode fingers or a center-to-center distance between adjacent second and third electrode fingers.

An acoustic wave device comprising:

• a piezoelectric layer made of lithium niobate with Euler angles (φ, θ, ψ) within a range of Expression (1), Expression (2), or Expression (3):
• (within a range of 0°±10°, 0° to 25°, any ψ) Expression (1);
• (within a range of 0°±10°, 25° to 100°, 0° to 75° [(1-(θ-50)2/2500)]1/2 or 180°-75° [(1−(θ-50)2/2500)]1/2 to 180°) Expression (2);
• and
• (within a range of 0°±10°, 180°-40° [(1−(ψ-90)2/8100)]1/2 to 180°, any ψ) Expression (3);
• a first comb-shaped electrode on the piezoelectric layer and including a first busbar and a plurality of first electrode fingers each including one end connected to the first busbar;
• a second comb-shaped electrode on the piezoelectric layer and including a second busbar and a plurality of second electrode fingers each including one end connected to the second busbar and being interdigitated with the plurality of first electrode fingers;
• and
• a reference potential electrode connected to a reference potential and including a plurality of third electrode fingers on the piezoelectric layer and aligned with the first electrode fingers and the second electrode fingers in a direction in which the first electrode fingers and the second electrode fingers are arranged, and a connection electrode connecting adjacent third electrode fingers;
• wherein
• the first comb-shaped electrode is connected to one of an input potential and an output potential, and the second comb-shaped electrode is connected to another of the input potential and the output potential;
• an order in which a first electrode finger, a second electrode finger, and a third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger define one period;
• leading ends of at least some of adjacent third electrode fingers, among all of the adjacent third electrode fingers, on a first busbar side are connected by the connection electrode;
• and
• G-B gap length≤G-F gap length, where the G-B gap length is a distance between the connection electrode connecting the leading ends of the adjacent third electrode fingers on the first busbar side and the first busbar, and the G-F gap length is a distance between the connection electrode and a leading end of one of the second electrode fingers.

An acoustic wave device comprising:

• a piezoelectric layer made of lithium niobate with Euler angles (φ, θ, ψ) (within a range of 0°±5°, within a range of −8°±14°, within a range of) 90°±5°;
• a first comb-shaped electrode on the piezoelectric layer, including a first busbar and a plurality of first electrode fingers each including one end connected to the first busbar, and being connected to an input potential;
• a second comb-shaped electrode on the piezoelectric layer, including a second busbar and a plurality of second electrode fingers each including one end connected to the second busbar and being interdigitated with the plurality of first electrode fingers, and being connected to an output potential;
• and
• a reference potential electrode connected to a reference potential and including a plurality of third electrode fingers on the piezoelectric layer and aligned with the first electrode fingers and the second electrode fingers in a direction in which the first electrode fingers and the second electrode fingers are arranged, and a connection electrode connecting adjacent third electrode fingers;
• wherein
• an order in which a first electrode finger, a second electrode finger, and a third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger define one period;
• when a direction in which the first electrode fingers, the second electrode fingers, and the third electrode fingers extend is an electrode finger extending direction, leading ends of the plurality of first electrode fingers and the plurality of second electrode fingers each face an electrode connected to one of the input potential, the output potential, and the reference potential, which is different from that of the electrode fingers, across a gap in the electrode finger extending direction;
• and
• G/px≥about 1, where G is a gap length of each gap along the electrode finger extending direction and px is a center-to-center distance between adjacent first and third electrode fingers or a center-to-center distance between adjacent second and third electrode fingers.

An acoustic wave device comprising:

• a piezoelectric layer made of lithium niobate with Euler angles (φ, θ, ψ) (within a range of 0°±5°, within a range of −8°±14°, within a range of) 90°±5°;
• a first comb-shaped electrode on the piezoelectric layer and including a first busbar and a plurality of first electrode fingers each including one end connected to the first busbar;
• a second comb-shaped electrode on the piezoelectric layer and including a second busbar and a plurality of second electrode fingers each including one end connected to the second busbar and being interdigitated with the plurality of first electrode fingers;
• and
• a reference potential electrode connected to a reference potential and including a plurality of third electrode fingers on the piezoelectric layer and aligned with the first electrode fingers and the second electrode fingers in a direction in which the first electrode fingers and the second electrode fingers are arranged, and a connection electrode connecting adjacent third electrode fingers;
• wherein
• the first comb-shaped electrode is connected to one of an input potential and an output potential, and the second comb-shaped electrode is connected to another of the input potential and the output potential;
• an order in which a first electrode finger, a second electrode finger, and a third electrode finger are arranged is such that, starting from the first electrode finger, the first electrode finger, the third electrode finger, the second electrode finger, and the third electrode finger define one period;
• leading ends of at least some of the adjacent third electrode fingers, among all of the adjacent third electrode fingers, on a first busbar side are connected by the connection electrode;
• and
• G-B gap length>G-F gap length, where the G-B gap length is a distance between the connection electrode connecting the leading ends of adjacent third electrode fingers on the first busbar side and the first busbar, and the G-F gap length is a distance between the connection electrode and a leading end of one of the second electrode fingers on the first busbar side.