In this article, a linear class AB and nonlinear class E power amplifier for WiMAX application are designed using the concept of equivalent capacitance. This concept provides a straightforward way to design power amplifiers at microwave frequencies without recurring to cumbersome formulas or optimization processes intended to get the output power and efficiencies figures associated to these amplifier classes. Furthermore, the use of optimization algorithms may lead to another class of operation if the intrinsic waveforms are not screened. © 2008 Wiley Periodicals, Inc.