US Patent 10056864 Efficient wideband envelope tracking power amplifier

A wideband envelope tracking power amplifier includes a plurality of low dropout voltage regulators (LDOs) including at least a first LDO and a second LDO. The wideband envelope tracking power amplifier also includes a single-input-multi-output (SIMO) voltage supply to output a plurality of voltage signals at different voltage levels, the voltage levels including a highest voltage level and one or more voltage levels lower than the highest voltage level. The SIMO voltage supply connects a first of the plurality of voltage signals at a first voltage level to the first LDO to form at least a portion of an envelope tracking voltage level signal, and connects a second of the plurality of voltage signals at a second voltage level less than or equal to the first voltage level to the second LDO to form at least another portion of the envelope tracking voltage level signal.