Surface acoustic wave device, and mobile communication device and sensor both using same
US7109828B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 14, 2003 |
| Grant date | Sep 19, 2006 |
| Priority date | — |
| Expiry date | Sep 17, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/02929
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a surface acoustic wave (SAW) device, such as a SAW resonator or a SAW filter, loss is minimized and steep characteristics are improved. IDT electrodes and a reflector are provided to a piezoelectric substrate cut out at a cut-angle which allows the substrate to excite a leaky surface acoustic wave (LSAW). The IDT electrodes have a given film thickness and a given pitch “p” of finger-electrodes. A phase velocity of the SAW is reduced to slower than a phase velocity “vb”of a slow shear wave propagating on the piezoelectric substrate, and a resonance frequency “f” satisfies a relation of 2×p≦vb/f. This structure allows the use of a Rayleigh surface acoustic wave (RSAW) which does not produce propagation loss, and improving insertion-loss and steep characteristics from those of a conventional SAW device using the LSAW.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.