A system is provided for adjusting an output power of a multi-stage power amplifier by controlling a supply voltage provided to one or more output amplifier stages of the power amplifier using a switching DC--DC converter. In general, the system includes a power amplifier including an input amplifier stage and one or more output amplifier stages coupled in series with the input amplifier stage. The one or more output amplifier stages receive a variable supply voltage from switching DC--DC conversion circuitry. The switching DC--DC conversion circuitry provides the variable supply voltage based on an adjustable power control signal. By controlling the variable supply voltage provided to the one or more output stages, the switching DC--DC conversion circuitry controls an output power of the power amplifier based on the adjustable power control signal.