A 5.5-GHz SiGe HBT Doherty amplifier using diode linearizer and lumped-element hybrid coupler
✍ Scribed by Haiwen Liu; Toshihiko Yoshimasu
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 421 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0895-2477
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✦ Synopsis
Abstract
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