A power amplifier (100, 200, 500, 800, 1100) for amplifying an input signal into an output signal is disclosed. The power amplifier (100, 200, 500, 800, 1100) comprises an input port (110) for receiving the input signal and an output port (130) coupled to an output transmission line (140) for providing the output signal. The power amplifier (100, 200, 500, 800, 1100) further comprises multiple sets of sub-amplifiers (150, 160, 170, 180) distributed along the output transmission line, and inputs of the subamplifiers are coupled to the input port, outputs of the sub-amplifiers are coupled to the output transmission line. At least two different supply voltages are provided for the sub-amplifiers in the multiple sets of sub-amplifiers (150, 160, 170, 180).
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