A linearized power amplifier includes a first amplification stage having a first transistor for amplifying an input signal and outputting a pre-amplified signal, and a second amplification stage having a second transistor for amplifying the pre-amplified signal. A phase injection circuit, connected to the gate of the first transistor and the gate of the second transistor, adjusts the phase of the input signal based on the pre-amplified signal so as to compensate for AM-AM distortion and AM-PM distortion.