POWER AMPLIFIER

PURPOSE:To improve the power efficiency in the analog mode while keeping the characteristic in the digital mode in the power amplifier used for a portable telephone set having both analog/digital modes. CONSTITUTION:The amplifier is provided with a linear power amplifier circuit 10 in the digital mode and a nonlinear power amplifier circuit 12 in the analog mode respectively. Outputs of both amplifiers are led to an output terminal 22 in response to the digital/analog mode by using a selection means 11 comprising strip lines 5, 6. Thus, in the digital mode since the linear amplification is implemented, the characteristic is improved, and since the efficient nonlinear amplification is implemented in the analog mode, the speech time is extended.