The present invention relates to a power amplification circuit of a mobile device for improving the efficiency and the linearity properties of the power amplifier. In one embodiment, the power amplifier improves these properties by controlling the input voltage of the supplemental amplifier so that the power amplifier operates as the Doherty mode in the low output power mode depending on the magnitude of the output power from the output unit and so that the input voltage of the supplemental amplifier may be increased up to satisfy the non-linear operational requirements of a power amplifier in the high output power mode. Moreover, because only the input voltage of the supplemental amplifier is controlled, the power amplifier can be implemented in a simple manner. Thus, the size of the power amplifier becomes small, which in turn reduces the cost of the power amplifier, among other things.