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This article describes a broadband Doherty power amplifier designed with a class AB and class C PA that is suitable for LTE Band-7 and Wi-Fi applications. The output matching network is theoretically analyzed, with emphasis on the effect of the auxiliary amplifier's non-ideal infinite output impedance on parasitic devices. A novel Doherty-like power amplifier (DPA) is constructed with 25 W, 2.2-2.8 GHz GaN HEMT transistors. The quarter-wave transformer that was previously used in the DPA topology was replaced by the corresponding Klopfenstein tapper network. Real-world prototype implementations have shown that this modification increases the achieved DPA bandwidth (BW) compared to conventional topologies while maintaining efficiency values. (Fractional bandwidth equals 24%) The DPA assumes an OBO value of 6 dB, which is typical for basic designs and explanations because the voltage level involved is 1:4 and the peak power amplifier is activated at half of the input voltage's dynamic range. However, in order to increase the OBO value, the signal must first be compatible with the PAPR value. This can be accomplished by adjusting the power divider in an asymmetrical manner. The OPBO range was extended using the asymmetric DPA technique.

We discuss the design, realization and experimental characterization of a GaN-based hybrid Doherty power amplifier for wideband operation in the 3-3.6-GHz frequency range. The design adopts a novel, simple approach based on wideband compensator networks. Second-harmonic tuning is exploited for the main amplifier at the upper limit of the frequency band, thus improving gain equalization over the amplifier bandwidth. The realized amplifier is based on a packaged GaN HEMT and shows, at 6 dB of output power back-off, a drain efficiency higher than 38% in the 3-3.6-GHz band, gain around 10 dB, and maximum power between 43 and 44 dBm, with saturated efficiency between 55% and 66%. With respect to the state of the art, we obtain, at a higher frequency, a wideband amplifier with similar performances in terms of bandwidth, output power, and efficiency, through a simpler approach. Moreover, the measured constant maximum output power of 20 W suggests that the power utilization factor of the 10-W (Class A) GaN HEMT is excellent over the amplifier band.