Closed loop power control of non-constant envelope waveforms using sample/hold

A radio frequency output power control system for use in communication systems that use a modulation scheme having a non-constant amplitude envelope, said power control system comprising:

• a power amplifier having an input to receive an input signal with a non-constant amplitude envelope, a power control input for receiving a power control signal, and an output for providing an amplified output signal;
• a track and hold circuit for tracking a reference signal;
• a first combiner for providing a difference between said reference signal and an output signal of said track and hold circuit, and
• a second combiner for providing a difference between a feedback signal and an output of said first combiner, wherein said power control signal is responsive to the difference between the feedback signal and the output of the first combiner.

A radio frequency output power control system comprising:

• a power amplifier coupled to an input signal for providing an amplifier output signal;
• a reference logarithmic unit coupled to a reference signal that is representative of a modulation of the input signal;
• a track and hold circuit coupled to said reference signal;
• a feedback logarithmic unit coupled to a feedback signal that is representative of a modulation of the amplifier output signal;
• and
• combiner means for providing a corrective signal to said power amplifier responsive to said reference signal, an output signal from said track and hold circuit, and said feedback signal by
• subtracting said output of said track and hold circuit from said reference signal that is representative of a modulation of the input signal, and
• subtracting said feedback signal from a difference between said reference signal the output of said track and hold circuit to provide the corrective signal that is coupled to the power amplifier.