A power amplifier comprises a level-discretization modulator (210) and a
mixing and amplifying stage (225), in combination with a properly
designed negative feedback path. The feedback path forms an error
compensation loop together with a properly selected forward path. The
forward path includes at least the mixing and amplifying stage (225),
which provides frequency up-conversion to the radio frequency band and
switch-based amplification. The negative feedback path includes a
down-conversion mixer (280) for down-conversion to the initial frequency
band, and compensates for distortion caused by components of the forward
path.