Cascaded surface wave device filters providing balanced and unbalanced signal connections
US5790000A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1996 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Jun 6, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/6463
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A cascaded surface wave device filter comprises two 2-pole surface wave device filters connected in cascade. The 2-pole filters each provide a balun function between balanced and unbalanced signal connections, and have either their unbalanced or their balanced signal connections interconnected in the cascade to reduce electromagnetic feedthrough and improve spurious mode suppression. The 2-pole filters are conveniently longitudinally coupled double mode surface wave resonators which are described, or transversely coupled double mode surface wave resonators. Higher order filters can be provided by connecting further 2-pole filters in the cascade. The cascaded filter is particularly useful for filtering at radio and intermediate frequencies in cellular radio equipment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.