Analysis and Design of the Novel Class-F/E Power Amplifier With Series Output Filter

Abstract

In this brief, a new lumped-element Class-F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /E and transmission-line (TL) Class-F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> power amplifiers are presented. It is shown that employing the series output filter (inverse Class-E) combined with a third harmonic control circuit (Class-F) leads to the new Class-F/E power amplifier. Compared with other switch-mode Class-E, Class-F/E, and Class-E/F power amplifiers, the proposed circuit has a higher maximum operating frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{\max }$ </tex-math></inline-formula> ), higher output power capability ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\mathrm{ p}}$ </tex-math></inline-formula> ), and lower peak drain voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V} _{\max }$ </tex-math></inline-formula> ). The capability of the Class-F/E mode with a series filter has been demonstrated by two design examples, one with lumped elements at 100 MHz and the other with transmission lines at 2.21 GHz. Two test boards of power amplifiers were measured, and high-performance results have been obtained. The simulated and measured drain efficiency (DE) of 86.4/85 %, output power of 41/40.6 dBm, and gain of 15.9/15.6 dB for the lumped-element Class-F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /E power amplifier have been obtained. On the other hand, the simulated/measured DE of 83/81%, power added efficiency of 79/78%, and output power of about 40/39.8 dBm for Class-F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> power amplifier at an input power of 27 dBm were obtained.