Phase characteristics of E class amplifier with various output networks


  • В.Г. Крижановський



phase frequency response, E class amplifier, E class oscillator, MOSFET, E class condition.


Phase shift of E class amplifiers with classical output network and output network that satisfies E class loading impedance conditions twice in the frequency band were studied by simulation and experimentally. The phase shift across switch in nominal operation mode was investigated analytically. The phase shift across switch in suboptimal class E operation mode that occurs while altering the operation frequency was investigated as well. The simulation method was the harmonic balance analysis using the switch model that considers the structure of power MOSFET device, namely, the existence of antiparallel diode pair that alters the switch current waveform. The input and transition capacitances of the transistor were considered. Experimental measurement of the phase shift was performed utilizing the recorded digitized waveforms of the switch input and output voltages by computing the phases of the voltages’ first harmonics with the help of Fast Fourier Transform. It was observed that characteristics of phase shift at switch output and amplifier output are dependent on the kind of load network. The relationship between the phase shift at the switch and hodograph of the loading impedance was demonstrated. For the network with double fulfilment of class E conditions that has a loop in the loading impedance hodograph the switch phase shift dependency has an extremum, which provides an opportunity to obtain the same phase shift at two frequencies within the operating frequency band. That facilitates control of the phase-frequency characteristic and the group delay of the amplifier. Knowledge of the phase-frequency dependency simplifies the conditions for calculation of the phase shift in the feedback network. The obtained results are useful for design of class E oscillator operating in a wide frequency band.


Крижановський В.Г., Макаров Д. Г., Чернов Д. В., Крижановський В. В. Автогенератори класу Е. ; за ред. В. Г. Крижановського / ДонНУ імені Василя Стуса. Вінниця : Нілан-ЛТД, 2017. 220 с.

Laskovski A. N., Yuce M. R. Class-E Oscillators as Wireless Power Transmitters for Biomedical Implants // 3rd Int. Symp. on Applied Sciences in Biomedical and Communication Technologies (ISABEL), 2010 Rome, 7-10 Nov. 2010. P. 1-5.

Ahmadi M. M., Salehi-Sirzar M. A Self-Tuned Class-E Power Oscillator // IEEE Transactions on Power Electronics. Vol. 34, Issue 5, May 2019, Page(s): 4434 – 4449.

Mikołajewski M. A self-oscillating h.f. power generator with a Class E resonant amplifier // Bulletin of The Polish Academy of Sciences Technical Sciences. 2013. V. 61, № 2. P. 527- 534

Apperley T., Nielsen J., Okoniewski M. A Class E/Fodd Power Oscillator Incorporating a Distributed Active Transformer // IEEE Transactions on Microwave Theory and Techniques. Vol. 68, No. 6, June 2020. P. 2409-2418.

Ahmadi M. M. and Pezeshkpour S. A Self-Starting Class-E Power Oscillator with an Inverting Gate Driver // IEEE Transactions on Industrial Electronics, doi: 10.1109/TIE.2019.2949533.

Inaba T., Koizumi H., Class E/F3 Tuned Power Oscillator // IEEE Transactions on Power Electronics. 2018; Vol. 33, No. 2. pp. 1420-1427.

Kryzhanovskyi V. G. Class-E Self-Excited Oscillator with Expanded Tuning Bandwidth // Telecommunications and Radio Engineering. Vol. 73, 2014 Issue 15. P. 1387-1395.

Krizhanovskii V.G., Printsovskii V.A. Class-E microwave Oscillator // Radioelectronics and Communication Systems. 2006. Vol. 49, No. 11, pp. 30-35.

Krizhanovski V.G., Chernov D.V., Grebennikov Andrei Low-Voltage Class E/F3 High Frequency Oscillator // 14th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering. Lviv-Slavske, Ukraine 2018. P: 607 – 611.

Grebennikov A., Sokal N. O. and M. J. Franco. Switchmode RF and Microwave Power Amplifiers, 2nd ed. Orlando, FL, USA: Academic, 2012, 667 p.

Kazimierczuk M. K. RF Power Amplifiers. 2nd ed. 2015 John Wiley & Sons Ltd. 686 p.

Raab F. H. Suboptimum operation of class-E RF power amplifiers // Proc. RF Technology Expo '89, Santa Clara, CA, pp. 85 – 98, Feb. 14 – 16, 1989.

Hayati M., Abbasi H., Kazimierczuk M. K. Sekiya, H. Analysis and Study of the Duty Ratio Effects on the Class-EM Power Amplifier Including MOSFET Nonlinear Gate-to-Drain and Drain-to-Source Capacitances // IEEE Transactions on Power Electronics, 1-1. doi:10.1109/tpel.2018.2810218.

Nagashima T., Wei X., Tanaka H.-A., Sekiya H. Locking Range Derivations for Injection-Locked Class-E Oscillator Applying Phase Reduction Theory // IEEE Trans. on Circuits and Systems-I: Regular Papers, Vol. 61, No. 10, Oct. 2014, p. 2904-2911.

Ishizaki T., Ikeda H., Yoshikawa Y., Uwano T. Analysis of phase characteristics of a GaAs FET power amplifier for digital cellular portable telephones // Electronics and Communications in Japan (Part II: Electronics). V.77, No. 4, April 1994. P. 1-9.

Krizhanovski V., Krizhanovski V., Grebennikov A. Class E oscillator with two switchable frequencies // 15th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering (TCSET – 2020). Lviv-Slavske, Ukraine, February 25 – 29, 2020.

Kazimierczuk M. K., Krizhanovski V. G., Rassokhina Ju. V., Chernov D. V., Class-E MOSFET Tuned Power Oscillator Design Procedure // IEEE Trans. On Circuits and Systems I. Regular Papers. V. 52, No. 6. June 2005.P.1138-1147.

How to Cite

Крижановський, В. (2020). Phase characteristics of E class amplifier with various output networks. Radiotekhnika, 3(202), 183–188.