A baseband predistorter for a transmitter with combined downconversion and demodulation in the feedback path

摘要

A baseband predistorter for a transmitter in a radiotelephone is controlled by feedback from the power amplifier output. In the feedback path the functions of down conversion and demodulation are combined by combining the frequency conversion LO signal 215 and the modulator/demodulator signal 212 in mixer 224. 226 is a DC offset compensator. The feedback signal may be supplied to DSP 240 intermittently via switches 227 and AD converters 228.