A 5.5-GHZ sige HBT Doherty amplifier using diode linearizer and lumped-element hybrid coupler

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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 μm2 HBTs are used for carried and peak amplifiers, respectively, and 26 μm2 HBT is used for linearizer. Results verify that the power gain, P1dB, 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.

Original languageEnglish
Pages (from-to)1554-1558
Number of pages5
JournalMicrowave and Optical Technology Letters
Issue number6
Publication statusPublished - 2008 Jun 1



  • Diode linearizer
  • Doherty amplifier
  • Lumped-element coupler
  • SiGe HBT

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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