Radio transceiver with duplex and notch filter

Details Radio transceiver with duplex and notch filter Radio transceiver with duplex and notch filter

1991-01-24

1993-11-30

Olms, Douglas W.

Multiplex communications

Wide area network

Packet switching

370 24, 455 19, 455 73, G08C 1500

Patent

active

052672344

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.

REFERENCES:
patent: 3656162 (1972-04-01), Mee
patent: 3761816 (1973-09-01), Condon
patent: 3771064 (1973-11-01), Hebert, Jr.
patent: 3803491 (1974-04-01), Osborn
patent: 3815137 (1974-06-01), Kaegebein
patent: 3987396 (1976-10-01), Kreger
patent: 4325140 (1982-04-01), Stitzer
patent: 4462098 (1984-07-01), D'Avello et al.
patent: 4706274 (1987-11-01), Baker et al.
patent: 4910481 (1990-03-01), Sasaki et al.
patent: 5023866 (1991-06-01), De Muro
298 NEC Research & Development 1987 Oct., No. 87 Tokyo, Japan "Hand-Held Portable Equipment for Cellular Mobile Telephone".

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