A Comparative Analysis of Doherty and Outphasing MMIC GaN Power Amplifiers for 5G Applications.

Area of Science:

• Electrical Engineering
• RF and Microwave Engineering
• Semiconductor Devices

Background:

• Fifth Generation (5G) wireless communications demand highly efficient and linear power amplifiers.
• Doherty power amplifiers (DPA) and outphasing power amplifiers (OPA) are key architectures for 5G systems.
• Gallium Nitride on Silicon (GaN-on-Si) technology offers advantages for high-frequency power amplification.

Purpose of the Study:

• To comparatively analyze the performance of fully integrated Doherty and outphasing power amplifiers for 5G applications.
• To evaluate linearity, efficiency, and power added efficiency (PAE) under various operating conditions.
• To assess the area efficiency of both amplifier designs.

Main Methods:

• Theoretical analysis and circuit design of both DPA and OPA configurations.
• Integration using pHEMT transistors from OMMIC's 100 nm GaN-on-Si technology (D01GH).
• Comparative performance evaluation at 1 dB compression point and 7.5 dB output back-off (OBO).

Main Results:

• OPA achieved a maximum PAE of 58.3% at 33 dBm output power; DPA achieved 44.2% PAE at 35 dBm.
• At 7.5 dB OBO, DPA demonstrated superior PAE (38.5%) compared to OPA (26.1%).
• DPA exhibited higher linearity, while OPA offered better peak efficiency. Optimized areas were 3.26 mm² (DPA) and 3.18 mm² (OPA).

Conclusions:

• The choice between DPA and OPA depends on specific 5G application requirements for linearity versus peak efficiency.
• Both DPA and OPA are viable candidates for 5G power amplification using GaN-on-Si technology.
• Area optimization techniques were successfully applied to both integrated circuit designs.