APPARATUS AND METHOD FOR OPERATING A TRANSMITTER

摘要

A linear transmitter includes a closed loop feedback path to maintain linearity of a power amplifier subsystem. The closed loop feedback path provides RF injection of one or more reference RF carrier signals (172, 174) combined with a radio frequency (RF) feedback signal (149) to generate a feedback RF error signal (173). A narrowband receiver (170) continuously monitors stability of the feedback RF error signal (173). A loop phase adjusting circuit (188) generates phase adjustments (189) to compensate for instabilities in the closed loop feedback path thereby maintaining stability of the PA RF output signal (146).