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A 5.5‐GHz SiGe HBT Doherty amplifier using diode linearizer and lumped‐element hybrid coupler
Author(s) -
Liu Haiwen,
Yoshimasu Toshihiko
Publication year - 2008
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.23432
Subject(s) - linearizer , amplifier , heterojunction bipolar transistor , electrical engineering , predistortion , hybrid coupler , linearity , engineering , linear amplifier , rf power amplifier , electronic engineering , optoelectronics , materials science , power dividers and directional couplers , voltage , transistor , cmos , bipolar junction transistor
A 5.5‐GHz Doherty amplifier using commercial 0.35‐μm SiGe HBT technology is proposed in this article. To improve the linearity, a predistortion using diode linearizer is adopted for biasing the peak amplifier. Moreover, to realize in fully on‐chip with circuit reduction, a 90° 3‐dB hybrid coupler and quarter‐wave transmission lines are implemented by lumped‐elements. In this design, 819 μm 2 HBTs are used for carried and peak amplifiers, respectively, and 26 μm 2 HBT is used for linearizer. Results verify that the power gain, P 1dB , and power added efficiency (PAE) of the proposed Doherty amplifier at 5.5 GHz are 8.4 dB, 31 dBm, and 30%, respectively. Also, the adjacent channel power ratio (ACPR) and the output signal's spectrum mask are given using the 54Mcps 64QAM modulated signal at 10 MHz offset. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1554–1558, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23432
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