Design of Doherty Amplifier for Efficiency Enhancement of 5G gNB Using GaN Technology

The recent trends in communication systems make use of modulation schemes like 256-QAM which offer excellent spectral efficiency but also exhibit from high Peak-to Average-Power-Ratio (PAPR). This makes it difficult to sustain the power amplifier’s efficiency at output back-off (BO). This paper proposes a Doherty power amplifier implemented using Qorvo GaN on SiC HEMT, which works in the n257 band, and its design methodology has been presented. An asymmetrical architecture has been opted as it offers better efficiency. A two-stage cascaded structure has been implemented along with harmonic suppression to improve the gain as well as efficiency performance. The design has also been simulated on an Arlon DiClad 880 substrate using grounded CPW lines. The asymmetrical DPA achieves a peak gain of 14 dB at 28 GHz, with PAE of 28 % at saturation and 21.6% at 6-dB BO. The maximum power delivered by the power amplifier is about 39.86 dBm.