High Power GaN-FET Amplifier with Reduced Memory Effects for W-CDMA Base Stations

Akio WAKEJIMA  Kohji MATSUNAGA  Yuji ANDO  Tatsuo NAKAYAMA  Yasuhiro OKAMOTO  Kazuki OTA  Naotaka KURODA  Masahiro TANOMURA  Hironobu MIYAMOTO  

IEICE TRANSACTIONS on Electronics   Vol.E90-C   No.5   pp.929-936
Publication Date: 2007/05/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.5.929
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: Compound Semiconductor and Power Devices
GaN-FET,  amplifier,  memory effects,  baseband impedance,  digital predistortion,  W-CDMA,  

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This paper describes a high power GaN-FET amplifier which is developed for wideband code division multiple access (W-CDMA) base stations. We design a bias network which is symmetrically arranged to the RF line (two way bias network) in order to reduce impedance at a baseband frequency of the multi-carrier W-CDMA signal. As a result, the amplifier with the two way bias network successfully suppressed memory effects. Therefore, the application of a DPD technique to the GaN-FET amplifier with the two way bias network demonstrates almost 20 dB linearity improvement in IM3 and considerable improvement in higher order IMD, resulting in low IMD of less than -50 dBc at the highest ever reported W-CDMA average output power of 76 W.