Abstract: An inverted Doherty power amplifier is proposed for the OFDM with the characteristic of high power to average power ratio (PAPR). The inverted structure changes its combining node from the end of the peak amplifier to the carrier amplifier, which improves the efficiency of load modulation in the carrier amplifier. Compared with the conventional Doherty power amplifier, the power added efficiency (PAE) of the proposed amplifier is improved by 3％ due to its effective impedance modulation. Measurement results show that the PAE of the proposed amplifier remains about 27.8％ with 10dB output power back-off. Its third-order intermodulation distortion (IMD3) and adjacent channel power ratio (ACPR) are improved by 2.5dB and 2dB respectively,which could be applied to OFDM communication well.

Key words: Doherty power amplifier, power to average ratio, power added efficiency