Open AccessAnalysis and design optimisation for inverse Class‐F GaN Doherty amplifier
Author(s) -
Kim Joonyhyung
Publication year - 2019
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2018.5124
Subject(s) - amplifier , adjacent channel , materials science , adjacent channel power ratio , dbc , power (physics) , linearity , rf power amplifier , electrical impedance , voltage , input impedance , electrical engineering , power added efficiency , electronic engineering , optoelectronics , engineering , cmos , physics , quantum mechanics
An analytical model of an inverse Class‐F (Class‐F‐1) Doherty power amplifier (DPA) with a proposed compensation method is presented. The derived model was shown to be effective in predicting the behaviour of the fundamental current and optimum load impedance in both a carrier and peaking cell for a Class F‐1 DPA. Based on the analysis results, the degradation of the RF performance, including the peak output power, efficiency, and linearity, caused by an inherent lower current driving of a peaking cell is also proven. To compensate this issue, a dynamic gate bias for a peaking cell using a proposed voltage shaping is introduced. For verification, a 2.4 GHz GaN Class‐F‐1 DPA was designed and fabricated. Using the proposed gate shaping method, improvements of the maximum output power of 2.6 dB and peak power drain efficiency of 5.6% are achieved compared with a conventional case. With a 10 MHz 6.5 dB peak‐to‐average power ratio signal, the Class‐F‐1 DPA achieves an average output power of 36 dBm with a DE of 54% at a 28 V supply voltage. The measured adjacent channel rejection ration under such conditions is below −30 dBc.