Multi-track SAW filter with reflectors and reversed polarity IDT connections
US5670920A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 24, 1995 |
| Grant date | Sep 23, 1997 |
| Priority date | — |
| Expiry date | Apr 24, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/02708
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A SAW filter comprising at least one group of N tracks, where N is an integer greater than 2, and including at least one input interdigitated transducer (IDT) spaced apart from at least one output IDT and a reflector disposed substantially collinear with and adjacent the input and output IDTs. The respective tracks are adapted to have different effective electro-acoustic lengths such that SAWs launched from respective input IDTs undergo at least one reflection at corresponding output IDTs and at least one reflection from the respective input IDTs prior to generating coherent signals from respective output IDTs. The different effective electro-acoustic lengths may be substantially provided by there being different physical separation between input and output IDTs of respective tracks, or by IDTs of respective tracks having different polarity connections of electrodes or different amounts of material disposed in respective tracks between the input and output IDTs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.