A Sub-6GHz Ultra-Compact 69.8% Drain Efficiency Harmonic Control Doherty Power Amplifier in GaN Technology

This paper presents a compact sub-6 GHz GaN Doherty power amplifier (DPA) with harmonic control for 5G. Utilizing harmonic tuning up to the 3rd harmonic, both amplifiers achieve high efficiency at peak and 6-dB OPBO. Harmonic impedance and intrinsic waveforms are optimized for performance. At 5.8 GHz, the measured peak Pout and P1dB are 37.9 dBm and 32.8 dBm, with 69.8% drain efficiency at peak Pout and 47.4% at OPBO. Digital predistortion (DPD) enhances average Pout from 28.9 to 31.9 dBm while maintaining < 3.5% EVM for 256-QAM. The DPA occupies just 3.2 mm² using 0.25-µm GaN HEMT technology.