Doherty power amplifier design employing direct input power dividing for base station applications

For base station applications, -3 dB hybrid coupler has been used for input power dividing stage of Doherty power amplifier (PA). The input direct dividing technique has only been applied for handset applications, because the coupler occupies a large size on a chip. However, this technique provides advantages on power gain and efficiency for base station applications, also. In this paper, we have proposed a design procedure of Doherty PA applying the input direct dividing technique. Implemented Doherty PA using two Cree CGH40045 GaN HEMT achieves excellent drain efficiency of 51.2% at 41 dBm output power for long term evolution (LTE) 1FA signal at 2.14-GHz. Moreover, the Doherty PA could be linearized to -45 dBc using the digital feedback predistortion technique.