Power amplifier utilizing the vector addition of two constant envelope carriers

摘要

A power amplifier having a gain factor of G for generating an output signal from a low power amplitude and phase modulated input signal. The power amplifier generates first and second constant envelope signals. Each constant envelope signal has the same frequency as said input signal. The first constant envelope signal has the same amplitude as the second constant envelope signal but differs in phase from the first constant envelope signal by an amount depending on the amplitude of the input signal. The output signal is generated by vectorially adding the first and second constant envelope signals. The amplifier has a feedback loop which operates by determining the difference in amplitude between the input signal and a signal having an amplitude 1/G times the amplitude of the output signal. The phase difference between the first and second constant envelope signals is altered so as to reduce the determined difference in amplitude. In one embodiment of the present invention, the difference in phase between the input and output signals is also measured. The phase difference is used to determine a phase increment that is added to both constant envelope signals so as to reduce the measured phase difference between the input and output signals.