Described are circuits and techniques to increase the effi ciency of radio-frequency (rf)
amplifiers including rf power amplifiers (PAs) through “supply modulation”(also referred to as
“drain modulation” or “collector modulation”), in which supply voltages provided to rf
amplifiers is adjusted dynamically (" modulated") overtime depending upon the rf signal
being synthesized. For the largest efficiency improve ments, a supply voltage can be
adjusted among discrete (Continued)

Described are circuits and techniques to increase the effi ciency of radio-frequency (rf)
amplifiers including rf power amplifiers (PAs) through" supply modulation"(also referred to as
“drain modulation” or “collector modulation”), in which supply voltages provided to rf
amplifiers is adjusted dynamically (" modulated”) over time depending upon the rf signal
being synthesized. For the largest efficiency improve ments, a supply voltage can be
adjusted among discrete voltage levels or continuously on a short time scale. The supply …