Patent attributes
Power amplifiers with adaptive bias for envelope tracking applications are provided herein. In certain embodiments, an envelope tracking system includes a power amplifier that amplifies a radio frequency (RF) signal and that receives power from a power amplifier supply voltage, and an envelope tracker that controls a voltage level of the power amplifier supply voltage based on an envelope of the RF signal. The power amplifier includes a current mirror having an input that receives a reference current, an output electrically connected to the power amplifier supply voltage, and a node that outputs a gate bias voltage. The power amplifier further includes a field-effect transistor that amplifies the radio frequency signal and a first depletion-mode transistor having a gate connected to the node of the current mirror and a source connected to a gate of the field-effect transistor.
