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.
Claims55
A surface acoustic wave apparatus comprising:
- a piezoelectric substrate;
- at least one surface acoustic wave filter including at least two interdigital transducers having electrode fingers and 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 is applied to at least a portion of electrode fingers of said at least one surface acoustic wave filter.
A surface acoustic wave apparatus comprising:
- a piezoelectric substrate;
- an input interdigital transducer including a plurality of electrode fingers;
- and
- an output interdigital transducer including a plurality of electrode fingers, said input interdigital transducer and said output interdigital transducer being arranged on said piezoelectric substrate in a direction in which a surface acoustic wave propagates so as to form a longitudinally-coupled-resonator-type;
- wherein
- weighting is applied to an inner electrode finger of said plurality of electrode fingers other than an outermost electrode finger of said plurality of electrode fingers of at least one of said input interdigital transducer and said output interdigital transducer.
Dependencies are inferred from the claim text.