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General Information
    • ISSN: 2010-3697
    • Frequency: Bimonthly
    • DOI: 10.7763/IJMO
    • Editor-in-Chief: Prof. Adrian Olaru
    • Executive Editor: Ms.Yoyo Y. Zhou
    • Abstracting/ Indexing: Engineering & Technology Digital Library, ProQuest, Crossref, Electronic Journals Library, Google Scholar, EI (INSPEC, IET).
    • E-mail ijmo@iacsitp.com
Prof. Adrian Olaru
University Politehnica of Bucharest, Romania
I'm happy to take on the position of editor in chief of IJMO. It's a journal that shows promise of becoming a recognized journal in the area of modelling and optimization. I'll work together with the editors to help it progress.
IJMO 2011 Vol.1(5): 380-384 ISSN: 2010-3697
DOI: 10.7763/IJMO.2011.V1.64

Performance Enhancement of Power Amplifier Class AB Push-Pull using Component Balun and Invert Doherty Combined with Negative Feedback

Sutthiphong Kophon, Peerapong Uthansakul, Monthippa Uthansakul, and Sampart Cheedket

Abstract—The System of storage ring in Synchrotron Light Research Institute (SLRI) is designed to compensate electron energy in storage ring using a cavity tuner. The cavity acquires a power from vacuum tube amplifier around 30-35 KW at the operating frequency of 118 MHz. To maintain such a high power, the system requires Power Amplifier (PA) having a high efficiency by solid state technology. This amplifier is a class AB push-pull type which has three important parts including Balun, matching circuit and DC bias. In this paper, we use Invert Doherty combined with Negative feedback to improve the PA performance. Invert Doherty technique can improve the efficiency of PA but the circuit is non-linear so it causes non-linear performance. Hence, in this paper, the authors propose a negative feedback in conjunction with invert Doherty for increasing linearity and power efficiency of PA. Also the use of lumped element instead of microstrip line in balun circuit is proposed to obtain the best efficiency. The performance measurement of Invert Doherty power amplifier combined with negative feedback (IDPA-NF) is presented and it is compared to the conventional PA with the same matching circuit. The results show that the proposed system can significantly improve the efficiency of class-AB amplifier.

Index Terms—Power amplifier, balun, Invert doherty, negative feedback, class AB push-pull amplifier

Sutthiphong Kophon, Peerapong Uthansakul and Monthippa Uthansakulare with the School of Telecommunication Enigineering, SuranareeUniversity of Technology, Nakhon Ratchasima, 30000, Thailand. (e-mail:m5340545@ sut.ac.th, uthansakul@sut.ac.th, mtp@sut.ac.th).
Sampart Cheedket is with the Accelerator Technology Division,Synchrotron Light Research Institute, Nakhon Ratchasima, 30000, Thailand.(e-mail: sampart@slri.or.th).


Cite: Sutthiphong Kophon, Peerapong Uthansakul, Monthippa Uthansakul, and Sampart Cheedket, "Performance Enhancement of Power Amplifier Class AB Push-Pull using Component Balun and Invert Doherty Combined with Negative Feedback," International Journal of Modeling and Optimization vol. 1, no. 5, pp. 380-384, 2011.

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