Class E Amplifier


Intro

The class E amplifier is classified as a switch mode amplifier similar to class D and F amplifiers. In these classes, the switching device doesn’t act as a linear component as it does in classes A, B, and C. Instead, it’s kept “on” (ideally Vds=0 and Rds=0) or “off”(Vds=f(ϴ) and Rds=∞). It has the advantages of having an ideal efficiency of 100% because Vds*Ids is kept at 0 for all ϴ by the pulse shaping network, realizable with stripline elements, and has a high maximum operating frequency for a given switching device be it a MOSFET, BJT, or the like. It also uses relatively few components and one of the capacitors is in parallel with the switching device meaning the device’s own capacitance becomes part of the network. With everything though, there are some disadvantages with using a class E amplifier. The Vds reaches a max voltage of about three times Vcc and the amplifier itself is highly nonlinear. A variation in the level of the input to the gate or base of the switching device doesn’t correlate well with the output power to the load. Not to leave this on a bad note, the class E amplifier is a great topology that has seen use in many places.

Where is/was it Used?

How I Came Across This and why I Built it

Design and Construction

Conclusion

Future

amp

8MHz 1W class E amplifier with its oscillator and gate drive

ideal_sim

A near ideal simulation of the class E amplifier

A full write-up with results is in progress.

Sources:

Colantonio, Paolo, Franco Giannini, and Ernesto Limiti. High Efficiency RF and 
	Microwave Solid State Power Amplifiers. Chichester, U.K.: J. Wiley, 2009. Print.

Cripps, Steve C. RF Power Amplifiers for Wireless Communications. Boston: Artech 
	House, 1999. Print.

Kazimierczuk, Marian K. RF Power Amplifiers. Chichester, West Sussex, U.K.: Wiley, 
	2008. Print.

Reynaert, Patrick, and Michiel Steyaert. RF Power Amplifiers for Mobile 
	Communications. Dordrecht: Springer, 2006. Print.

Shirvani, Alireza, and Bruce A. Wooley. Design and Control of RF Power Amplifiers. 
	Boston: Kluwer Academic, 2003. Print.