A Broadband Doherty Power Amplifier With a New Load Modulation Network

In this paper, we proposed a new load modulation method to improve bandwidth and efficiency at output power back-off (OBO) of the Doherty Power Amplifier (DPA). The quarter wavelength transmission line behind the combination point of the impedance inverter was replaced with a dual-frequency matching circuit to matche the impedance value of the combination point to the load impedance in this method. The dual-frequency matching was used to compensate for the frequency dispersion effect that occurs in the traditional impedance inverter network and to a certain extent solves the bandwidth limitation of the Doherty power amplifier. To verify the proposed theory, a broadband high-efficiency power amplifier was designed and manufactured for 5G mobile communications. Measurement results show that the designed DPA is in the range of 2.4-3.7GHz, the saturated output power is above 42dBm, the saturated drain efficiency is 61.2%-68.4%, and the 6dB back-off efficiency is 49.7%-61.4%.