Surface acoustic wave device
AssigneeFujitsu Limited
InventorsSeiji Mineyoshi, Osamu Kawachi
Life of this patent
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Abstract
A surface acoustic wave device is designed such that an inter-digital transducer and a reflector have the same grating cycle. The electrode dye width of the reflector is larger than that of the inter-digital transducer, or the electrode dye width is smaller than the distance between the electrodes by changing at least one of the inter-digital transducer and the reflector. Connecting the thus structured surface acoustic wave devices to a single piezoelectric substrate as resonators in a ladder form produces a surface acoustic wave device for use in a filter.
Claims35
A surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate wherein ##EQU9## .alpha. indicates a coefficient (.noteq.1);
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate wherein
- L5/L7<L6/L8;
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate wherein ##EQU10## .alpha. indicates a coefficient (.noteq.1);
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate wherein
- L5=L6;
- L7=L8;
- L5.noteq.L7-L5;
- .alpha. indicates a coefficient (.noteq.1);
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate wherein ##EQU11## .alpha. indicates a coefficient (.noteq.1);
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A method of providing a surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate, comprising a step of providing that:
- ##EQU12## .alpha. indicates a coefficient (.noteq.1);
- L5 indicates an electrode finger width of the inter-digital transducer;
- L6 indicates the electrode finger width of the reflector;
- L7 indicates a grating cycle of the inter-digital transducer;
- and wherein
- L8 indicates the grating cycle of the reflector.
A method of providing a surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate, comprising a step of providing that:
- L5/L7<L6/L8,
- L5 indicates an electrode finger width of the inter-digital transducer,
- L6 indicates the electrode finger width of the reflector,
- L7 indicates a grating cycle of the inter-digital transducer, and providing that
- L8 indicates the grating cycle of the reflector.
A method of providing a surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate, comprising a step of providing that:
- ##EQU13## .alpha. indicates a coefficient (.noteq.1), L5 indicates an electrode finger width of the inter-digital transducer,
- L6 indicates the electrode finger width of the reflector,
- L7 indicates a grating cycle of the inter-digital transducer, and providing that
- L8 indicates the grating cycle of the reflector.
A method of providing a surface acoustic wave device comprising a piezoelectric substrate, an inter-digital transducer provided on a surface of the piezoelectric substrate, and reflectors mounted as opposed to each other on both sides of the inter-digital transducer on the surface of the piezoelectric substrate, comprising a step of providing that:
- ##EQU14## .alpha. indicates a coefficient (.noteq.1), L5 indicates an electrode finger width of the inter-digital transducer,
- L6 indicates the electrode finger width of the reflector,
- L7 indicates a grating cycle of the inter-digital transducer, and providing that
- L8 indicates the grating cycle of the reflector.
Dependencies are inferred from the claim text.