A radio frequency output power control system for use in communication
systems is disclosed. The power control system is used for a modulation
scheme having a non-constant amplitude envelope and comprises a power
amplifier having a power amplifier input for receiving an input signal
with a non-constant amplitude envelope, a power control input for
receiving a power control input, and a power amplifier output for
providing an amplified output signal. The power control system also
includes a track and hold circuit for tracking a measured reference power
signal that is representative of a modulation of the input signal, and
subtraction means for subtracting an output of the track and hold circuit
from the measured reference power signal to provide a difference signal
that is coupled to the power control input.