Radio transceiver with duplex and notch filter
US5267234A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 24, 1991 |
| Grant date | Nov 30, 1993 |
| Priority date | — |
| Expiry date | Jan 24, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/48
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A transceiver for a cellular telephone, particularly a portable telephone, comprises a transmitter and a receiver coupled to a common antenna by an antenna duplex filter. The duplex filter comprises two passband filters connected respectively to the transmitter and the receiver. The receiver comprises a first amplifier. A notch filter tuned to the transmit frequency is connected to the output of the amplifier. The notch filter enables the filtering performance of the receive filter to be relaxed, and the location of the notch filter(s) at the output of amplifier means that the insertion loss is less critical. The requirement for lower filtering performance enables the duplex filter to be smaller and less costly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.