A class E power amplifier including coupling coils is proposed for application in a wireless power transfer system using magnetic coupling. The proposed amplifier is directly connected to the coils with no discrete components for harmonic filtering and dc feeding, which could cause efficiency degradation of the amplifier. The system with the differential amplifier shows 6.95 W of transmitted power and 44.6% transmission efficiency at 6.8 MHz with 14-cm distant coils. The power-added efficiency of the amplifier is 92.1% with a 14 V supply voltage, excluding the coupling efficiency of the wireless power transfer network.
2. Choi, J. and C. Seo, "High-efficiency wireless energy transmission using magnetic resonance based on negative refractive index metamaterial," Progress In Electromagnetics Research, Vol. 106, 33-47, 2010.
3. Wei, X. C. and E. P. Li, "Simulation and experimental comparison of different coupling mechanisms for the wireless electricity transfer," Journal of Electromagnetic Waves and Applications, Vol. 23, No. 7, 925-934, 2009.
4. Cannon, B. L., J. F. Hoburg, D. D. Stancil, and S. C. Goldstein, "Magnetic resonant coupling as a potential means for wireless power transfer to multiple small receivers," IEEE Trans. Power Elect., Vol. 24, No. 7, 1819-1825, Jul. 2009.
5. Jang, , B.-J., S. Lee, and H. Yoon, "HF-band wireless power transfer system: Concept, issues, and design," Progress In Electromagnetics Research, Vol. 124, 211-231, 2012.
6. Laskovski, A. N. and M. R. Yuce, "Class-E oscillators as wireless power transmitters for biomedical implants," Proc. 3rd Int. Symp. Appl. Sci. Biomedical and Communication Tech., 1-5, Rome, Nov. 2010 .
7. Ma, Q., M. R. Haider, S. Yuan, and S. K. Islam, "Power-oscillator based high e±ciency inductive power-link for transcutaneous power transmission," Proc. 55rd IEEE Int. Midwest Symp. Circuits and Systems, 537-540, Seattle, 2010.
8. Juntunen, E., D. Dawn, S. Pinel, and J. Laskar, "A high-efficiency, high-power millimeter-wave oscillator using a feedback class-e power amplifier in 45nm CMOS," IEEE Microw. Wireless Compon. Lett., Vol. 21, No. 8, 430-432, Aug. 2011.
9. Jimenez-Martin, J. L., V. Gonzalez-Posadas, J. E. Gonzalez-Garcia, F. J. Arques-Orobon, L. E. Garcia-Munoz, and D. Segovia-Vargas, "Dual band high efficiency class ce power amplifier based on CRLH diplexer," Progress In Electromagnetics Research, Vol. 97, 217-240, 2009.
10. Grebennikov, , A. V., "Switched-mode rf and microwave parallelcircuit class E power amplifiers," Int. J. RF and Microw. Computer-Aided Eng., Vol. 14, No. 1, 21-35, Jan. 2004.
11. Son, H.-C., J. W. Kim, D.-H. Kim, K.-H. Kim, and Y.-J. Park, "Self-resonant coil with coaxial-like capacitor for wireless power transfer," Proc. Asia-Pacific Microw. Conf., 90-93, Melbourne, 2011.