An Integrated Doherty Power Amplifier Module Based on an Advanced GaN-on-Si HEMT Technology and a Wideband Power Combiner

In this letter, a wideband and highly integrated Doherty power amplifier (PA) module for 5G massive MIMO (mMIMO) base station transceivers (BTSs) is presented, leveraging a novel GaN-on-Si technology. The advanced GaN heterostructure field-effect transistor (HFET) technology delivers high power density and 75% drain efficiency (DE) at 3.6 GHz, while exhibiting very favorable output impedances for wideband matching. The module incorporates a simple and compact output combiner concept with effective second-harmonic termination, demonstrating very low dispersion over a wide RF bandwidth (600 MHz) at the output of 0.25- $\mu \text {m}$ gate length GaN-on-Si transistors. The manufactured PA module achieves an efficiency of 51%–53% and a gain of more than 15.8 dB across the 3.4–4.0-GHz band under a 100-MHz LTE signal with 8-W average output power. Linearized ACLR of −63.0 and −42.0 dBc, achieved through digital predistortion (DPD) for 20- and 530-MHz LTE signals, respectively, confirms the significant advantages of the wideband combiner concept in enabling wideband load modulation architectures by fully exploiting second-harmonic termination.