Patent ID: 7119621

Claim:
A power amplifier for receiving and amplifying an input signal and outputting an output signal, comprising: N power amplifying units (N is an integer larger than 1) connected in parallel so as to output amplified signals in response to the input signal; an output combining unit for combining the output signals from the N power amplifying units and outputting a combined signal as the output signal of the power amplifier; and an amplitude controlling unit for selectively turning ON each of the N power amplifying units based on an amplitude of the input signal, the amplitude controlling unit comprising: N amplitude adjusters (N is an integer larger than 1) connected in parallel for adjusting the amplitude of the input signal of the power amplifier; and a controller for selectively turning ON each of the N power amplifying units and controlling the amplitude adjusters so that an amplitude of the output signal becomes a substantially continuous function with respect to the amplitude of the input signal.