Abstract: A front end circuit for an RF dual band GSM/DCS phone includes a first channel including an elliptical high-pass filter, a first SAW filter, and a low noise amplifier and a second channel including a second SAW filter and a second low noise amplifier. The output of each channel is alternately switchable to a single-side band mixer circuit. This front end circuit arrangement provides significantly reduced cost and part count over other approaches.

Abstract: The present invention provides increased geographical coverage and system capacity for mobile/portable radio transceivers using adjacent and typically separate radio communication frequency bands. A radio that transceives in just one frequency band is adapted to provide a configurable duplexing arrangement to permit communications in extended frequency bands. Duplexing circuitry is connected between the radio antenna and the radio transmitter and receiver. Depending upon the mode of operation of the radio transceiver, switches are selectively operated for variously configuring the antenna, duplexer circuitry, receiver, and transmitter to permit communications in a first or a second set of transmit/receive frequency bands. In one preferred example embodiment, only a single duplexer is employed connected to the antenna and transceiving circuitry through plural switches.