An adjustable stage in an amplifier. The adjustable stage generally comprises a first common node, a second common node and a plurality of independently selectable parallel amplifier segments. Each of the parallel segments may have an input at the first common node and an output at the second common node, a transistor and an inductor to resonate with a capacitance at a base of the transistor. The present invention advantageously provides a relatively compact power amplifier with an extended output power range at which the amplifier is highly efficient. In preferred embodiments, the input and output matching characteristics are generally independent of the number of selected output amplifier segments.