Surface acoustic wave matched filter with dispersive substrate and saw group velocity based output electrode design
US6275123A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1999 |
| Grant date | Aug 14, 2001 |
| Priority date | — |
| Expiry date | Jul 12, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/6416
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A surface acoustic wave matched filter for use in a spread spectrum communication system is disclosed. The surface acoustic wave matched filter includes a substrate having dispersity and is composed of a sapphire main body and a piezoelectric aluminum nitride. A tap distance L of an output side electrode is designed on the basis of a group velocity v.sub.g instead of a phase velocity v.sub.s in order to match the tap distance L with an input spread spectrum signal and to improve a correlation peak level of an output demodulated signal. When the tap distance L is set to satisfy a condition of v.sub.g /f.sub.1.times.0.97.ltoreq.L.ltoreq.v.sub.g /f.sub.1.times.1.02, a decrease in the correlation peak level of the matched filter can be improved from 7 dB to a value smaller than 3 dB, and S/N of the output demodulated signal can be increased. Thus, the disclosed device renders it no longer necessary to process the output demodulated signal by a complicated and power consuming circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.