A Symmetric Wideband Doherty Power Amplifier for the n78 - 5G NR Frequency Band

This paper describes the design of a wideband Doherty power amplifier for fifth generation mobile network applications in sub-6 GHz frequency bands. The presented symmetric design uses different drain-supply voltages for the main and peaking amplifiers to achieve high efficiency at deep power back-off levels. The advantages and disadvantages over conventional asymmetric designs are discussed focusing on the case of wideband Doherty power amplifiers. A new Doherty com-biner is proposed which equalises the impedance transformation ratio between the back-off and peak power points. Finally, a proof-of-concept prototype is developed which can achieve higher than 50% drain efficiency for power levels between peak output power and 8 dB power back-off, for the frequency range between 3.3 GHz and 3.8 GHz.