Surface acoustic wave apparatus and communication unit
AssigneeMurata Manufacturing Co., Ltd.
InventorsOsamu Shibata, Yuichi Takamine, Hiroki Watanabe, Masaru Yata, Yoichi Sawada
Life of this patent
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Abstract
A surface acoustic wave apparatus includes three longitudinally-coupled-resonator-type interdigital transducers (IDTs) having a balanced-to-unbalanced conversion function, which are provided on a piezoelectric substrate in a direction in which a surface acoustic wave (SAW) propagates. Weighting is applied to at least one of the IDTs. For example, among the electrode fingers of the IDT located on the left side, an apodization-weighted electrode finger is provided for one of the electrode fingers positioned adjacent to the central IDT.
Claims54
A surface acoustic wave apparatus comprising:
- a piezoelectric substrate;
- at least one surface acoustic wave filter including at least a first interdigital transducer and second and third interdigital transducers on opposing sides of the first interdigital transducer, each of the first, second, and third interdigital transducers have electrode fingers, and the first, second and third interdigital transducers are arranged on the piezoelectric substrate in a direction in which a surface acoustic wave propagates;
- and
- an input signal terminal and an output signal terminal for said at least one surface acoustic wave filter;
- wherein
- at least one of said input signal terminal and said output signal terminal is connected to a balanced signal terminal;
- and
- weighting applied to the second interdigital transducer is different from weighting applied to the third interdigital transducer.
A surface acoustic wave apparatus comprising:
- a piezoelectric substrate;
- a first interdigital transducer;
- and
- second and third interdigital transducers on opposing sides of the first interdigital transducer;
- wherein
- each of the first, second, and third interdigital transducers includes a plurality of electrode fingers;
- and
- weighting applied to the first interdigital transducer is different from weighting applied to second and third interdigital transducers.
Dependencies are inferred from the claim text.