A Sub-6 Ghz Ultra-Compact 69.8

This paper presents a compact sub- 6 GHz GaN Doherty power amplifier (DPA) with harmonic control for 5 G. 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 P 1 dB 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3.2 ~\text{mm}^{2}$</tex> using <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.25 \min \mu \mathrm{m}$</tex> GaN HEMT technology.