A distributed matching/combining network suitable for Doherty power amplifiers covering more than an octave frequency band

This contribution presents a ground breaking distributed matching/combining network that allows to develop ultra-broadband Doherty Power Amplifiers (DPAs). In 73 % of fractional bandwidth, from 1.2 GHz to 2.6 GHz, input return loss lower than -18 dB is demonstrated with 1.82 resistance transformation ratio. The active load modulation capability is verified, resulting in a resistance modulation index within 1.8 and 2.1 in the overall frequency range. In order to quantify the benefits, both matching and combining performance of the proposed network are compared with the conventional output network of DPAs. The solution is validated through the realization of a hybrid GaN prototype with more than 83 % of fractional bandwidth. From 1 GHz to 2.6 GHz, continuous wave measurements show efficiency levels within 85 %-45 % and within 57 %-35 % at saturation and 6dB of output power back-off, respectively. Measurement results applying a 5 MHz 3gpp signal with carrier frequency from 1.2 GHz to 2.5 GHz confirm the efficient amplification of the prototype with envelope varying signals.