A power amplifier includes generation, tracking and usage of an envelope of an input RF signal. To improve upon the efficiency of the power amplifier, various configurations include using the tracked envelope, for example, an OFDM signal, to improve the average efficiency. Suitable hardware/software in the form of circuitry, logic gates, and/or code functions to generate and track an envelope of an input RF signal and modulate one or more of the input supply voltage, cascode gate bias or parallel PA branches using the tracked envelope.