One embodiment of the present invention relates to a power amplifier comprising a plurality of amplifying elements connected in a serial-parallel matrix configuration, containing parallel columns having amplifying elements connected in series. The parallel columns are connected to a common output path coupled to a supply voltage source configured to provide an equal supply voltage to each of the columns. One or more input signals (e.g., RF input signals) are connected to the power amplifier by way of input terminals on a first row of amplifying elements. The remaining amplifying elements have control terminals that are connected to independent control signals, which allow each amplifying element to be operated independent of the other amplifying elements in the matrix. This selective operation of amplifying elements allows for improved efficiency over a wide range of power amplifier output powers.