Envelope tracking power amplifier robust to battery depletion

A wideband envelope tracking power amplifier, which is robust to battery depletion, is introduced. An integrated boost converter keeps a stable operation of the PA supply modulator. Even at the battery depletion from 4.2 V to 2.8 V, there is no significant degradation of output power and linearity in the power amplifier. Moreover, the efficiency degradation by the additional regulator is minimized for the novel supply modulator architecture proposed in this work. The fabricated 2.535 GHz envelope tracking power amplifier presents max/min power-added efficiencies of 32.3/26.2% for 10 MHz BW 3 GPP LTE standard along the battery voltage from 4.2 V to 2.8 V.