Surface acoustic wave filter device on 40.degree. to 42.degree. rotated Y-X LITAO.sub.3
US5874869A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Sep 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H2250/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A surface acoustic wave device includes a piezoelectric substrate of a LiTaO.sub.3 single crystal, the crystal having X, Y and Z axes and a cut plane. The X axis of the crystal is oriented in a direction of propagation of surface acoustic waves. The cut plane of the crystal is rotated around the X axis at a rotated angle from the Y axis to the Z axis, the rotated angle being in a range between 40.degree. and 42.degree.. A pair of reflectors are formed on the substrate and aligned in a row in the direction of propagation. Interdigital transducers are formed on the substrate and aligned in the row in the direction of propagation, the interdigital transducers interposed between the reflectors, each interdigital transducer having pairs of mutually opposed primary electrode fingers and secondary electrode fingers, the interdigital transducers including at least a front transducer, a middle transducer and a rear transducer aligned in the row in the direction of propagation. In the device, a ratio of the number of pairs of the electrode fingers in one of the front transducer and the rear transducer to the number of pairs of the electrode fingers in the middle transducer is in a range betw…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.