Surface acoustic wave filters
US4733207A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 12, 1987 |
| Grant date | Mar 22, 1988 |
| Priority date | — |
| Expiry date | Jun 12, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/14505
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A surface acoustic wave filter comprising; a first bidirectional ID transducer (5) of symmetrical form; a second ID transducer (1) acoustically coupled with the first transducer and comprising two parts (1A, 1B) each of which parts is in the form of one half of a respective bidirectional ID transducer (9 or 11) of symmetrical form, the two parts being positioned with respect to one another and the first transducer so that when respectively excited by corresponding signals of different phases they co-operate to produce a unidirectional acoustic signal propagating towards the first transducer from one side thereof; and a third transducer (3) acoustically coupled with the first transducer and comprising two parts (3A, 3B ), each of which parts is electrically connected in parallel with a respective one of the two parts of said second transducer, and each of which parts of the third transducer is effectively in the form of the mirror image about the center line (7) of the first transducer of the other half of the bidirectional transducer whose one half constitutes the part of the second transducer with which it is connected. The invention provides a filter of intrinsically low insertio…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.