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A Study for Efficiency Improvement of Feedforward Power Amplifier by Using Doherty Amplifier  

Lee Taek-Ho (Department of Electronic and Electrical Engineering, SungKyunKwan University)
Jung Sung-Chan (Department of Electronic and Electrical Engineering, SungKyunKwan University)
Park Cheon-Seok (Department of Electronic and Electrical Engineering, SungKyunKwan University)
Publication Information
The Journal of Korean Institute of Electromagnetic Engineering and Science / v.16, no.11, 2005 , pp. 1059-1066 More about this Journal
Abstract
This paper reports an application of Doherty amplifier for efficiency improvement of feedforward power amplifier(FPA). For performance analysis, we measured 15 W average output power using WCDMA 4FA input signal with a center frequency 2.14 GHz. The applied Doherty amplifier presents the characteristics of high efficiency and low linearity in comparison to the class AB amplifier, and it was used as main amplifier of FPA fir efficiency improvement. To analyze the change of characteristic, tow Doherty amplifiers whose linearity and efficiency are different were applied. The applied FPAs are improved about $2\%$ or more performance in efficiency, but decreased in linearity on 15 W average output power. We additionally modified the coupling factor(CF) of the error loop and the error amplifier capacity for linearity improvement. Aa a result, the efficiency improvement and high linearity resulted from the change of CF and error amplifier capacity. However, we think if the linearity of Doherty amplifier were more than 35 dBc, the FPA would improve the performance about $2\%$ or more efficiency and maintain enough linearity.
Keywords
Feedforward; Doherty; Amplifier;
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  • Reference
1 K. J. Parsons, P. B. Kenington, 'The efficiency of a feedforward amplifier with delay loss', IEEE Transactions on Vehicular Tech., vol. 43, no. 2, May 1994
2 Y. Yang, J. Cha, B. Shin, and B. Kim, 'A fully matched N-way Doherty amplifier with optimized linearity', IEEE Microwave Theory Tech., vol. 51, no. 12, pp. 986-993, Dec. 2003   DOI   ScienceOn
3 W. H. Doherty, 'A new high efficiency power amplifier for modulated waves', Proceedings of the IRE, vol. 24, no. 9, pp. 1163-1182, 1936   DOI   ScienceOn
4 P. B. Kenington, High Linearity RF Amplifier Design, Artech House Inc., Norwood, MA, 2000
5 J. C. Pedro, J. Perez, 'Accurate simulation of GaAs MESFET's intermodulation distortion using a new drain-source current model', IEEE Microwave Theory Tech., vol. 42, no. 1, pp. 25-33, Jan. 1994   DOI   ScienceOn
6 N. Pothecary, Feedforward Linear Power Amplifiers, Artech House Inc., Norwood, MA, 1999
7 S. C. Cripps, RF Power Amplifiers for Wireless Communications, Artech House Inc., Norwood, MA, 1999
8 Y. Yang, J. Yi, Y. Y. Woo, and B. Kim, 'Optimum design for linearity and efficiency of a microwave Doherty amplifier using a new load matching technique', Microwave Journal, pp. 20-36, Dec. 2001
9 J. Cha, J. Kim, B. Kim, J. Lee, and S. Kim, 'Highly efficiency power amplifierfor CDMA base station using Doherty configuration', IEEE Microwave Theory Tech., vol. 52, pp. 533-536, Jun. 2004