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US 12,633,896 B2Granted
Acoustic wave element, acoustic wave filter device, and multiplexer
AssigneeMurata Manufacturing Co., Ltd.
InventorYohei Konaka
Life of this patent
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Abstract
An acoustic wave element includes a piezoelectric substrate, an IDT electrode including comb electrode fingers, and a reflector including reflective electrode fingers. An average value of all pitches of the comb electrode fingers is smaller than an average value of all pitches of the reflective electrode fingers. When a total number of the comb electrode fingers is defined as N, at least one n-th end-side pitch satisfying 1≤n≤(0.233×N) is smaller than the average value of all the pitches of the comb electrode fingers.
Claims16
An acoustic wave element comprising:
- a piezoelectric substrate;
- an interdigital transducer (IDT) electrode on the piezoelectric substrate and including a pair of comb-shaped electrodes;
- and
- a reflector adjacent to the IDT electrode in an acoustic wave propagation direction;
- wherein
- each of the pair of comb-shaped electrodes includes a plurality of comb electrode fingers extending in a direction intersecting with the acoustic wave propagation direction;
- the reflector includes a plurality of reflective electrode fingers extending in the direction intersecting with the acoustic wave propagation direction;
- when an inter-center distance in the acoustic wave propagation direction between adjacent electrode fingers among the electrode fingers of each of the IDT electrode and the reflector is defined as a pitch, an average value of all pitches of the plurality of comb electrode fingers is smaller than an average value of all pitches of the plurality of reflective electrode fingers;
- and
- when a total number of the plurality of comb electrode fingers is defined as N, the comb electrode finger closest to the reflector among the plurality of comb electrode fingers is defined as a first end-side electrode finger, electrode fingers in a direction from the first end-side electrode finger toward a center of the IDT electrode are sequentially defined as an n-th end-side electrode finger where n is a natural number, a pitch between the n-th end-side electrode finger and an (n+1)-th end-side electrode finger is defined as an n-th end-side pitch, in a case where N is an odd number, an (N/2−0.5)-th end-side electrode finger is set as a first inner-side electrode finger and in a case where N is an even number, an (N/2)-th end-side electrode finger is defined as the first inner-side electrode finger;
- electrode fingers in a direction from the first inner-side electrode finger toward the reflector are sequentially defined as an m-th inner-side electrode finger where m is a natural number, a pitch between the m-th inner-side electrode finger and an (m−1)-th inner-side electrode finger is defined as an m-th inner-side pitch, and an average value of all pitches of an electrode finger that is the n-th end-side electrode finger satisfying n>0.233×N and is also the m-th inner-side electrode finger satisfying m>0.167×N among the plurality of comb electrode fingers is set as a reference pitch, and at least one m-th inner-side pitch satisfying Formula 2A below is larger than the reference pitch:
- 1≤m≤(0.167×N) Formula 2A.
9 more elements
An acoustic wave element comprising:
- a piezoelectric substrate;
- an interdigital transducer (IDT) electrode on the piezoelectric substrate and including a pair of comb-shaped electrodes;
- and
- a reflector adjacent to the IDT electrode;
- wherein
- each of the pair of comb-shaped electrodes includes a plurality of comb electrode fingers extending in a first direction;
- the reflector includes a plurality of reflective electrode fingers extending in the first direction, and is adjacent to the IDT electrode in a second direction intersecting with the first direction;
- when an inter-center distance between adjacent electrode fingers in the second direction among the electrode fingers of each of the IDT electrode and the reflector is defined as a pitch, an average value of all pitches of the plurality of comb electrode fingers is smaller than an average value of all pitches of the plurality of reflective electrode fingers;
- and
- when a total number of the plurality of comb electrode fingers is defined as N, the comb electrode finger closest to the reflector among the plurality of comb electrode fingers is defined as a first end-side electrode finger, electrode fingers in a direction from the first end-side electrode finger toward a center of the IDT electrode are sequentially defined as an n-th end-side electrode finger where n is a natural number, in a case where N is an odd number, an (N/2−0.5)-th end-side electrode finger is defined as a first inner-side electrode finger and in a case where N is an even number, an (N/2)-th end-side electrode finger is defined as the first inner-side electrode finger, electrode fingers in a direction from the first inner-side electrode finger toward the reflector are sequentially defined as an m-th inner-side electrode finger where m is a natural number, and a pitch between the m-th inner-side electrode finger and an (m−1)-th inner-side electrode finger is defined as an m-th inner-side pitch, at least one m-th inner-side pitch satisfying Formula 2A below is larger than the average value of all the pitches of the plurality of comb electrode fingers:
- 1≤m≤(0.167×N) Formula 2A.
8 more elements
Dependencies are inferred from the claim text.