Output harmonics, output power, and efficiency control for radio frequency (RF) power amplifiers

A duty cycle controller for a wireless communication device, the duty cycle controller comprising:

• a delay line configured to receive a frequency-modulated (FM) signal having a constant envelope waveform;
• and
• control circuitry coupled to the delay line and configured to:
• adjust a duty cycle of the FM signal based at least in part on a target output power associated with a power amplifier of the wireless communication device, the adjusting of the duty cycle including:
• delaving the FM signal by a duration associated with the target output power;
• and
• combining the FM signal with the delayed FM signal based on combinational logic;
• and
• output the FM signal, after adjusting the duty cycle, to the power amplifier for transmission over a wireless communication channel.

A system comprising:

• a modulator configured to modulate data onto a carrier signal according to a constant envelope frequency modulation (FM) scheme;
• a power amplifier configured to amplify the modulated carrier signal for transmission over a wireless communication channel;
• and
• a duty cycle controller configured to adjust a duty cycle of the modulated carrier signal, prior to being amplified by the power amplifier, based at least in part on a target output power associated with the power amplifier, the adjusting of the duty cycle including:
• delaying the modulated carrier signal by a duration associated with the target output power, and
• combining the modulated carrier signal with the delayed modulated carrier signal based on combinational logic.