A GaN based Power Amplifier Module for 5G Basestations

Abstract

This study presents a compact and low-cost Power Amplifier Module (PAM) for the RF power generation of 5G sub-6GHz massive Multiple Input and Multiple Output small-cell base stations. The module is a hybrid design realized on a 6mm x 10mm Rogers RO4350B RF laminate with bare-die Gallium Nitride (GaN) High Electron Mobility (HEMT) transistors for amplification and lumped components for filtering, matching, biasing circuits, and stabilization networks. The operating frequency is centered at 3.5GHz, a commonly deployed 5G New Radio (NR) band. The module has two amplification stages, which operate in Class-AB mode with differing conduction angles to equalize AM-AM and AM-PM responses for higher compression point, linearity and power-added efficiency (PAE). The design has a 24dB gain with 38 % PAE at 5W output power. The input and output return losses are 8 dB and 6 dB, respectively. The large and small signal measurement results agree with simulation results, with some performance shifts over the frequency explained in the letter. The back-fitting procedures are developed, and the measurement data is verified with an optimized circuit.