A Broadband Doherty Power Amplifier Design By Optimizing Its Load Modulation Network

A kind of broadband power amplifier for wide-band coverage of the next-generation base station communications systems is obtained through using GaN HEMT transistor CGH40010 supplied by CREE as carrier or peak power amplifiers, and a novel load modulation network (LMN) is presented in this paper. With continuous wave (CW) measurements, the results for the obtained Doherty power amplifier (DPA) show that the saturation drain efficiency is between 61% and 71%, the 6 dB back off efficiency is greater than 35%, and the maximum efficiency is 52% in the 2.8-4.0 GHz frequency range. The performance of this improved DPA is more excellent than that of the unimproved one. Furthermore, 20 MHz long term evolution (LTE) modulated signals are applied for and digital pre-distortion (DPD) to evaluate its linearization performance. And lower than -46 dBc adjacent leak power ratio (ACLR) can be achieved at 3.5 GHz.