Novel GaN-Based Digital Class-E Doherty PA with High 12dB OBO Efficiency

This paper presents a novel GaN-based 3-chip digital class-E Doherty power amplifier (PA) module designed to extend the back-off capabilities of the digital Doherty to deep back-off. Three identical class-E PA chips with digital input driving are combined off-chip in a two-way Doherty configuration for high efficiency in the 5G FR1 frequency band. For a single-tone input signal, the measured final-stage drain efficiency at 3.5 GHz peaks at 68% at 12 dB back-off, with a saturated output power of 33 dBm. Under a 20 MHz, 9 dB-PAPR digital OFDM input, the PA module delivers a drain efficiency of 55% at the same frequency.