Efficiency optimization of WCDMA driven two-way Doherty power amplifiers over wide power range

This paper studies the effects of the design parameter on the efficiency of two-way Doherty power amplifiers driven by signals having high peak to average power ratio (PAPR). The optimal value of the design parameter (alpha) is calculated as a function of the output power back-off for two WCDMA signals having a PAPR of 7.3 dB and 9.8 dB, respectively. It is shown that, for the considered signals, the optimal value of alpha depends only on the output power back-off. Parametric study demonstrated that while the optimal value of alpha results in high efficiency over a reduced power range, a judicious sub-optimal choice of the design parameter will lower the peak average efficiency but considerably increase the high efficiency power range of the Doherty amplifier.