Miniature Design Technique of Stabilized C-Band p-HEMT MMIC Doherty Power Amplifier with Lumped Element Load Modulator

Tsuyoshi YOSHIDA  Yoichiro TAKAYAMA  Ryo ISHIKAWA  Kazuhiko HONJO  

IEICE TRANSACTIONS on Electronics   Vol.E99-C   No.10   pp.1130-1139
Publication Date: 2016/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.1130
Type of Manuscript: Special Section PAPER (Special Section on Microwave and Millimeter-Wave Technology)
doherty amplifier,  microwave,  power amplifier,  GaAs HEMT,  series connected load type,  MMIC,  broadband,  

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A broadband miniature GaAs p-HEMT MMIC Doherty power amplifier (DPA) with a series connected load operating at the C band has been developed. To minimize the circuit size, a lumped-element load modulation circuit without a quarter wavelength transmission line has been introduced to MMIC technology. For both an input and output power divider/combiner circuit, two baluns are used to reduce the length of the phase adjuster circuit without causing instability. An inherent DPA instability problem related with the degenerated sub-harmonic frequency has been analyzed with the S and T parameters of DPA circuit components, resulting in a novel stabilized circuit. The developed stabilized DPA delivered a maximum power added efficiency (PAE) of 49% and a maximum output power of 23.4dBm. Greater than 40% PAE below a 10-dB input back-off from a saturated output power is obtained for a frequency range of 6.1 to 6.8GHz.