A dual-band mobile phone transmitter for GSM or DCS bands

摘要

A transmitter signal source 70 provides a DCS1800 signal via first amplifier 110, the output of which is further amplified by an amplifier 120 and a final output amplifier 130. A GSM900 output signal is provided by downconverting the DCS 1800 signal in mixer 150, using local oscillator 140. The GSM900 signal output by mixer 150 is amplified by cascaded amplifiers 160 and 170. Because the first amplifier 110, which is common to both DCS and GSM bands, operates in only one band, its efficiency can be improved. There may be more than two frequency bands. The transmitter circuit may be fabricated in GaAs.