A technique to boost the output power of portable radio terminals without increasing the power dissipation is described. The input to the terminal transmit amplifier is modified by a peak-to-average reduction and an amplitude pre-distortion circuit, prior to being applied to the amplifier. The peak-to-average reduction and pre-distortion circuit modifies the baseband samples before applying any amplitude pre-distortion. The amplitude pre-distortion uses a lookup table updated at power up or power down of the terminal radio, during idle time, just before origination of a call, before termination of a call, or while the call is active. During the updating of the lookup table the radio could be in its normal transmit mode, or transmit into a dummy load.