Advanced design of a double Doherty power amplifier with a flat efficiency range

This paper reports a new double Doherty power amplifier (DDPA) with a flat efficiency range, which consists of two-stage amplifiers. When the two-way DPA is used as the main peaking amplifier, the driving peaking cell with class-C bias turns the DPA off before the saturation of the main carrier amplifier. Three efficiency-peaking points are achieved with the additional Doherty operation by the main peaking amplifier after the saturation of the main carrier amplifier. For verifications, the driving and main amplifiers are designed and implemented with 2-W and 10-W GaN HEMTs, respectively, at 2.14 GHz. From the continuous wave (CW) results, three efficiency-peaking points are obtained at approximately 9-, 5-, and 0-dB back-off powers with over 42% drain efficiency. For one-carrier wide-band code division multiple access (WCDMA) signal, the DDPA shows good digital predistortion linearization performance.