A Predistortion Diode Linearizer Technique with Automatic Average Power Bias Control for a Class-F GaN HEMT Power Amplifier

Akihiro ANDO  Yoichiro TAKAYAMA  Tsuyoshi YOSHIDA  Ryo ISHIKAWA  Kazuhiko HONJO  

IEICE TRANSACTIONS on Electronics   Vol.E94-C    No.7    pp.1193-1198
Publication Date: 2011/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.1193
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
class-F power amplifier,  GaN HEMT,  diode linearizer,  intermodulation distortion,  diode bias control,  

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A novel predistortion technique using an automatic average-power bias controlled diode is proposed to compensate the complicated nonlinear characteristics of a microwave class-F power amplifier using an AlGaN/GaN HEMT. The optimum value for diode bias voltage is automatically set according to detected input average RF power level. A high-efficiency 1.9 GHz class-F GaN HEMT power amplifier with the automatic average-power bias control (ABC) diode linearizer achieves an improved third order inter-modulation distortion (IMD3) of better than -45 dBc at a smaller than 6 dB output power back-off from a saturated output power of 27 dBm, without changing drain efficiency. The adjacent channel leakage power ratio (ACPR) for 1.9 GHz W-CDMA signals is below -40 dBc at output power levels of smaller than 20 dBm for the class-F power amplifier.