Comparison of Doherty PAs for Wideband Watt-level GaAs MMIC Implementations

Two fully integrated GaAs Doherty power amplifiers are presented for 5G FR1 applications requiring operation over the n77 (3.3–4.2 GHz) and n79 (4.4–5.0 GHz) bands. To assess the capabilities of different Doherty combiners in wideband scenarios, two versions are designed and compared: a first implementation using a direct quarter-wave-based combiner and a second version employing an inverted topology, theoretically expected to offer more broadband performance. Both designs employ stacked transistor cells and a balanced architecture to enhance output power and load mismatch resilience. Experimental results show that both implementations achieve comparable performance as the additional losses introduced by the inverted combiner limit its theoretical benefits in terms of efficiency and gain uniformity over the full band. Both achieve more than 34.5 dBm saturated output power, 20 dB small-signal gain, and power-added efficiency above 22% over a 6-dB output back-off.