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A 55‐W high efficiency unbalanced three‐stage Doherty power amplifiers for various output power back‐offs
Author(s) -
Kim JiYeon,
Kang Yunho,
Kim JongHeon
Publication year - 2018
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.31170
Subject(s) - amplifier , impedance matching , electrical engineering , electrical impedance , transformer , electronic engineering , rf power amplifier , power (physics) , current sense amplifier , linear amplifier , output impedance , direct coupled amplifier , engineering , operational amplifier , voltage , physics , cmos , quantum mechanics
High efficiency unbalanced three‐stage Doherty power amplifiers (DPA) for input signals with various peak to average power ratios (PAPR) are presented. The amplifier uses three GaN devices of equal size. The output power back‐off (OPBO) at the efficiency peak of the amplifier can be extended and reduced according to the input signals with various PAPR. This is achieved by adjusting the impedances of the λ/4 impedance transformers at the individual amplifier output stages in the three‐stage DPA without the use of additional circuitries and by changing the impedance matching circuit at the input stages of the amplifiers. The current of the individual amplifiers in the three‐stage DPA is calculated according to the PAPR of the input signals. The impedances of the λ/4 impedance transformers are determined by the current ratio for the main, first peaking, and second peaking amplifiers and are implemented by microstrip lines. 55 W unbalanced three‐stage DPAs for extended and reduced OPBO are designed and fabricated to be operated at the frequency of 1810 MHz.