A Hybrid Integrated and Low-Cost Multi-Chip Broadband Doherty Power Amplifier Module for 5G Massive MIMO Application

In this paper, a hybrid integrated broadband Doherty power amplifier (DPA) based on a multi-chip module (MCM), whose active devices are fabricated using the gallium nitride (GaN) process and whose passive circuits are fabricated using the gallium arsenide (GaAs) integrated passive devices (IPD) process, is proposed for 5G massive multiple-input multiple-output (MIMO) application. An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance, and a single-driver architecture is adopted for a chip with high gain and small area. The proposed DPA has a bandwidth of 4.4–5.0 GHz that can achieve a saturation of more than 45 dBm. The gain compression from 37 dBm to saturation power is less than 4 dB, and the average power-added efficiency (PAE) is 36.3% with an 8.5 dB peak-to-average power ratio (PAPR) in 4.5–5.0 GHz. The measured adjacent channel power ratio (ACPR) is better than –50 dBc after digital predistortion (DPD), exhibiting satisfactory linearity.