Power amplifier providing high efficiency

A power amplifier containing a DC-DC converter, a linear amplifier and a control block. The DC-DC converter receives power from a power source and generates a regulated power supply voltage whose magnitude is controlled by the magnitude of a control signal provided to the DC-DC converter. The linear amplifier receives an input signal and generates a power-amplified output signal, and receives the regulated power supply voltage for operation. The control block is coupled to receive the input signal, and generates the control signal with a magnitude based on the amplitude of the input signal. The regulated power supply voltage is modulated based on the amplitude of the input signal, for peak-to-peak amplitudes of the power-amplified output greater than or less than or equal to the magnitude of the power source. High efficiency for the power amplifier is thereby obtained.