Radio frequency signal processing and amplification in cartesian loop amplifiers

摘要

A Cartesian Loop radio frequency transmitter has its I and Q channel processing circuitry implemented in an ASIC, which produces a forward path output signal in a first radio frequency band. At least one further stage of frequency up-conversion of the signal in the first band occurs prior to radio frequency power amplification with corresponding additional down-conversion in the feed-back path. Use of a feed-forward bandstop filter, or a feedback loop containing a bandpass filter in an amplifier forward path is disclosed for the purpose of suppressing out-of-band noise in the transmitted signal.