GaN MMIC Doherty Amplifier with Dual-Path Group Delay Compensation

This paper addresses the misalignment in load modulation and back-off efficiency fluctuations caused by phase dispersion in broadband Doherty power amplifiers (DPA). By implementing a differential group delay compensation strategy in the input matching network (IMN), broadband phase errors are effectively suppressed. A two-stage integrated DPA chip operating at $5.3-7.5 \mathrm{GHz}$ ($34.6 \%$ fractional bandwidth) is designed using a $0.25-\mu \mathrm{m}$ GaN-HEMT process. Post-layout simulations demonstrate a saturated output power of $40.8-42.0 \mathrm{dBm}$, saturated power-added efficiency (PAE) of $53.6-56.0 \%$, and $6-\mathrm{dB}$ back-off PAE of $\mathbf{4 1. 6 - 4 8. 6 \%}$ with fluctuations below $\mathbf{7 \%}$. This approach significantly enhances the consistency of broadband back-off efficiency and the flatness of the modulation process.