Linear Algebra Elucidates Class-E Power Amplifiers [Educator’s Corner

Abstract

Power amplifiers are generally classified into two categories, one of which collects linear amplifiers, such as class A and push-pull class B. They behave in an analog manner, i.e., the input signal waveform remains unchanged through amplification. Therefore, they are usually characterized under a small-signal assumption. The other category collects saturated amplifiers, such as classes D, E, and F. They employ an active device that behaves as a quickly alternating on-off switch, like the one used in binary-logic circuits. This switch-mode operation brings an extremely high dc-to-RF power conversion efficiency. In particular, a class-E amplifier works for high-power broadcasting, radio communication, and recently, emerging wireless power transfer applications. With this background, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Microwave Magazine</i> ’s July/August 2018 special issue was on class-E amplifiers <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> .