volume | PIER Journals

Abstract

Doherty type Power Amplifier (DPA) design is one of the most practical efficiency enhancement methods that provide moderate linearity. Asymmetrical device usage and employment of bias adaptation are among the most commonly used Doherty architectures in recent applications. In this paper, the efficiency performances of bias adapted DPA and asymmetrical DPA are compared based on the new efficiency expression that is derived in terms of the conduction angle. The efficiency of bias adapted DPA is analyzed in terms of conduction angle of the peaking device; various bias waveforms are proposed and their effects on enhanced efficiency performance are demonstrated. This paper also facilitates an approach to determine the required relative periphery of the peaking amplifier in order to have a fully load modulated asymmetrical DPA. Both DPA structures are designed and implemented at the output power of 50 dBm with nearly 60% drain efficiencies in 6 dB load modulation region. The measurements verify the better efficiency characteristics of the bias adapted DPA and asymmetric DPA in comparison to the conventional DPA. For the first time in the literature, as a fair comparison, the performances of asymmetrical DPA and bias adapted DPA are compared on the same platform and their advantages as well as drawbacks are demonstrated using measurement results.

1. Doherty, W. H., "A new high efficiency power amplifier for envelope modulated signals," Proc. of the Ins. of Radio Eng., Vol. 24, No. 9, 1163-1182, 1936. Google Scholar

2. Raab, F. H., "Efficiency of Doherty RF power-amplifier systems," IEEE Trans. on Broadcasting, Vol. 33, No. 3, 77-83, 1987.
doi:10.1109/TBC.1987.266625 Google Scholar

3. Cripps, S. C., "Efficiency enhancement techniques," RF Power Amplifiers for Wireless Communication, Chapter 8, 219-250, Artech House, Norwood, MA, 1999. Google Scholar

4. Bousnina, S., "Analysis and design of high-efficiency variable conduction angle Doherty amplifier," IET Mic. Ant. Prop., Vol. 3, No. 3, 416-425, 2009.
doi:10.1049/iet-map.2007.0307 Google Scholar

5. Zhou, H.-J. and H.-F. Wu, "Design of an S-band two-way inverted asymmetrical Doherty power amplifier for long term evolution applications," Progress In Electromagnetics Research Letters, Vol. 39, 73-80, 2013. Google Scholar

6. Markos, A. Z., P. Colantonio, F. Giannini, R. Giofre, M. Imbimbo, and G. Kompa, "A 6W uneven Doherty power amplifier in GaN technology," Proc. of 2nd European Microwave Integrated Circuits Conf., 299-302, 2007. Google Scholar

7. Hussaini, A. S., I. T. Elfergani, J. Rodriguez, and R. A. Abd-Alhameed, "Efficient multi-stage load modulation radio frequency power amplifier for green radio frequency front end," IET Science Meas. Tech., Vol. 6, No. 3, 117-124, 2012.
doi:10.1049/iet-smt.2011.0127 Google Scholar

8. Li, X., W. H. Chen, Z. H. Feng, and F. M. Ghannouchi, "Design of dual-band tri-way GaN Doherty power amplifier with frequency dependent power division," Electron. Lett., Vol. 48, No. 13, 797-798, 2012.
doi:10.1049/el.2012.1203 Google Scholar

9. Li, X., W. Chen, Z. Lu, Z. Feng, Y. Chen, and F. M. Ghannouchi, "Design of dual-band multi-way Doherty power amplifiers," IEEE MTT-S Int. Microw. Symp. Dig., 1-3, 2012. Google Scholar

10. Lee, M. W., S. H. Kam, Y. S. Lee, and Y. H. Jeong, "A highly efficient three-stage Doherty power amplifier with flat gain for WCDMA applications," Journal of Electromagnetic Waves and Applications, Vol. 24, No. 17-18, 2537-2545, 2010.
doi:10.1163/156939310793675619 Google Scholar

11. Cripps, C., "Doherty and Chireix," Advanced Techniques in RF Power Amplifier Designs, Chapter 2, 33-72, Artech House, Norwood, MA, 2002. Google Scholar

12. Lee, Y. S., M. W. Lee, and Y. H. Jeong, "A highly linear and efficient two-stage GaN HEMT asymmetrical Doherty amplifier for WCDMA applications," Microwave and Optical Technology Letters, Vol. 51, No. 6, 1464-1467, 2009.
doi:10.1002/mop.24387 Google Scholar

13. Markos, A. Z., K. Bathich, F. Golden, and G. Boeck, "A 50W unsymmetrical GaN Doherty amplifier for LTE applications," Proc. of 40th European Microwave Conference, 994-997, 2010. Google Scholar

14. Jung, S.-C., O. Hammi, and F. M. Ghannouchi, "Design Optimization and DPD linearization of GaN-based unsymmetrical Doherty power amplifiers for 3G multicarrier applications," IEEE Trans. Microw. Theory Tech., Vol. 57, No. 9, 2105-2113, 2009.
doi:10.1109/TMTT.2009.2027076 Google Scholar

15. Lee, Y., M. Lee, and Y. Jeong, "Unequal-cells-based GaN HEMT Doherty amplifier with an extended efficiency range," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 8, 536-538, 2008.
doi:10.1109/LMWC.2008.2001015 Google Scholar

16. Kim, I., J. Moon, S. Jee, and B. Kim, "Optimized design of a highly efficient three-stage Doherty PA using gate adaptation," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 10, 2562-2574, 2010.
doi:10.1109/TMTT.2010.2063831 Google Scholar

17. Moon, J., J. Kim, I. Kim, J. Kim, and B. Kim, "A wideband envelope tracking Doherty amplifier for WiMAX systems," IEEE Microw. Wireless Compon. Lett., Vol. 18, No. 1, 49-51, 2008.
doi:10.1109/LMWC.2007.912019 Google Scholar

18. Yang, Y., J. Cha, B. Shin, and B. Kim, "A microwave Doherty amplifier employing envelope tracking technique for high efficiency and linearity," IEEE Microw. Wireless Compon. Lett., Vol. 13, No. 9, 370-372, 2003.
doi:10.1109/LMWC.2003.817130 Google Scholar

19. Kenington, P. B., "RF power amplifier design," High-linearity RF Amplifier Designs, Chapter 3, 89-134, Artech House, Norwood, MA, 2000. Google Scholar

20. Sedra, S. and K. C. Smith, "MOS field-effect transistors," Microelectronic Circuits, 2nd Edition, Chapter 4, 235-376, Oxford University Press, Oxford, NY, 2004. Google Scholar

21. Colantonio, P., F. Giannini, R. Giofre, and L. Piazzon, "Doherty power amplifiers and GaN technology," Proc. of IEEE MIKON, 1-4, 2010. Google Scholar

22. Darraji, R., F. M. Ghannouchi, and O. Hammi, "Generic load-pull-based design methodology for performance optimization of Doherty amplifiers," IET Science Meas. Tech., Vol. 6, No. 3, 132-138, 2012.
doi:10.1049/iet-smt.2011.0023 Google Scholar

23. Kim, J., J. Cha, I. Kim, S. Y. Noh, C. S. Park, and B. Kim, "Advanced design methods of Doherty power amplifier for wide bandwidth, high efficiency base station power amplifiers," Proc. of 35th Eurepean Microwave Conference, Vol. 2, 4-6, 2005. Google Scholar

24. Kim, B., J. Kim, I. Kim, and J. Cha, "The Doherty power amplifier," IEEE Microwave Magazine, Vol. 7, No. 5, 42-50, 2006.
doi:10.1109/MW-M.2006.247914 Google Scholar

25. Boulejfen, N., A. Harguem, O. Hammi, F. M. Ghannouchi, and A. Gharsallah, "Analytical prediction of spectral regrowth and correlated and uncorrelated distortion in multicarrier wireless transmitters exhibiting memory effects," IET Mic. Ant. Prop., Vol. 4, No. 6, 685-696, 2010.
doi:10.1049/iet-map.2008.0401 Google Scholar

26. Kim, B., J. Kim, I. Kim, J. Cha, and S. Hong, "Microwave Doherty power amplifier for high efficiency and linearity," Proc. of IEEE INMMIC, 22-25, 2006. Google Scholar

27. Zhou, R. W., Y. Dong, and J. F. Bao, "A 460MHz Doherty amplifier for IMT-advanced system," Progress In Electromagnetics Research Letters, Vol. 32, 187-195, 2012. Google Scholar

28. Oh, I. Y., K. H. Ra, and C. S. Park, "Dynamic linearisation overcoming sweet spot of Doherty amplifier for WiBRO handset," IET Mic. Ant. Prop., Vol. 2, No. 8, 904-912, 2008.
doi:10.1049/iet-map:20070301 Google Scholar

Dr. Necip Sahan

Prof. Simsek Demir