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http://dx.doi.org/10.7471/ikeee.2018.22.4.1019

Extraction of Optimal Operation Condition of QAM Envelope Tracking System using Combined Cost Function of Bandwidth and Efficiency  

Kim, Changwook (Dept. of Electronics Engineering, Hankuk University of Foreign Studies)
Park, Youngcheol (Dept. of Electronics Engineering, Hankuk University of Foreign Studies)
Publication Information
Journal of IKEEE / v.22, no.4, 2018 , pp. 1019-1024 More about this Journal
Abstract
In this paper, we suggest a combined cost function to find out the optimal operation of an envelope tracking system, and evaluated its performance with Quadrature Amplitude Modulation (QAM) waveform, with which envelope tracking coefficients for the peak drain efficiency and the bandwidth of power amplifiers are determined. Based on the classical envelope tracking theory, the operation of the supply modulator, which is a key part of the envelope tracking process, is modeled and analyzed mathematically. Then characteristics of the modulator by setting envelope shaping function as a cubic polynomial and sweeping the coefficients of this function was analyzed. By sweeping the coefficients, efficiency and bandwidth at each condition with 64-QAM signal was used to obtain optimal point of the supply modulator. Compared to the conventional shaping functions, the optimized function showed the bandwidth reduction by 12.7 percent point while the efficiency was maintained.
Keywords
PAPR; Power Amplifier; Efficiency; Envelope Tracking; Supply Modulator;
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Times Cited By KSCI : 1  (Citation Analysis)
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