Linear RF amplifier with polar feedback

A system for power amplification of a partially modulated radio-frequency (RF) signal representative of at least a phase component of an original waveform, the system comprising:

• a feedback-controlled amplitude modulator configured to amplitude-modulate the partially modulated RF signal based upon a feedback-corrected amplitude control signal and to generate a modulated RF signal;
• a power amplifier coupled to the feedback-controlled amplitude modulator and configured to amplify the modulated RF signal and to generate an amplified RF output signal;
• an amplitude detector coupled to the power amplifier and configured to detect an amplitude characteristic of the amplified RF output signal and to generate an amplitude feedback signal;
• a feedback network coupled to the amplitude detector and the feedback-controlled amplitude modulator and configured to generate the feedback-corrected amplitude control signal based upon a difference between the amplitude feedback signal and an amplitude component of the original waveform;
• and
• a direct-digital synthesizer coupled to the feedback-controlled amplitude modulator and configured to generate the phase-modulated RF signal based upon the phase component of the original waveform.

A system for power amplification of a radio-frequency (RF) signal comprising:

• a feedback-controlled IQ modulator configured to modulate the RF signal based upon a pair of feedback-corrected control signals and to generate a modulated RF signal;
• a power amplifier coupled to the feedback-controlled IQ modulator and configured to amplify the modulated RF signal and to generate an amplified RF output signal;
• an amplitude detector coupled to the power amplifier and configured to detect an amplitude characteristic of the amplified RF output signal and to generate an amplitude feedback signal;
• and
• a feedback network coupled to the amplitude detector and the feedback-controlled IQ modulator and comprising a pair of multipliers configured to generate the pair of feedback-corrected control signals based upon a pair of IQ signals representative of at least a phase component of an original waveform, and a difference between the amplitude feedback signal and an amplitude component of the original waveform.

A system for power amplification of a radio-frequency (RF) signal comprising:

• a feedback-controlled modulator configured to modulate the RF signal based upon a feedback-corrected control signal and to generate a modulated RF signal;
• a power amplifier coupled to the feedback-controlled modulator and configured to amplify the modulated RF signal and to generate an amplified RF output signal;
• an amplitude detector coupled to the power amplifier and configured to detect an amplitude characteristic of the amplified RF output signal and to generate an amplitude feedback signal;
• a feedback network coupled to the amplitude detector and the feedback-controlled modulator and configured to generate the feedback-corrected control signal based upon a difference between the amplitude feedback signal and an amplitude component of the RF signal;
• and
• a fixed phase shifter configured to generate a phase shifted signal based upon a phase characteristic of a phase-modulated RF signal;
• the amplitude detector comprising an IQ demodulator coupled to the power amplifier and the fixed phase shifter, the IQ demodulator including a local oscillator configured to receive the phase shifted signal and to oscillate in phase with the phase-modulated RF signal, the amplitude feedback signal having an in-phase component signal generated by the IQ demodulator based upon the amplified RF output signal.