A Fully-Integrated GaN Doherty Power Amplifier Module with a Compact Frequency-Dependent Compensation Circuit for 5G massive MIMO Base Stations

This paper presents a fully-integrated two-stage GaN Doherty Power Amplifier (DPA) Module for 5G massive MIMO base stations. To overcome the size limitation of PAs in massive MIMO base-stations while meeting the wideband requirement, a new compact frequency-dependent compensating circuit with zero-phase offset in the peaking amplifier is proposed. The proposed circuit not only increases the bandwidth of the DPA, but also works as matching network, resulting in compact and flexible design. The proposed method is applied to a 10mm×6mm two-stage GaN DPA module. Measurements show that the DPA module achieves more than 50.4% drain efficiency and 42.9% PAE over 400MHz for 3.4-3.8GHz with -50dBc ACLR under 20MHz signal with PAPR of 8.0dB, after DPD. Furthermore, for 10 carrier aggregated signal (10×20MHz), the DPA exhibited 43.9% PAE with -48.6dBc ACLR after DPD. The proposed DPA has efficiency comparable to DPAs with larger sizes, demonstrating size advantage of the proposed configuration.