Load-Pull Investigation of a High-Voltage RF-Power GaN-HEMT Technology in Supply Modulated Applications

O. Bengtsson, S.A. Chevtchenko, R. Doerner, P. Kurpas and W. Heinrich

Published in:

Frequenz, vol. 65, no. 7-8, pp. 217-224 (2011).

Copyright © 2007-2011. Walter de Gruyter GmbH & Co. KG. All rights reserved. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the Walter de Gruyter GmbH & Co. KG.


In this paper the potential and limitations of using a high-voltage GaN-HEMT RF-power technology with supply modulation for increased back-off efficiency is investigated. Based on extensive on-wafer class-AB loadpull characterization at various supply voltages and input power levels followed by advanced post-processing of the measured data, the possible efficiency improvement with supply modulation is explored and the technology and device limitations are discussed. The analysis is conducted for operation at three different maximum modulation voltages 15 V, 28 V, and 48 V. Post-processing of the measurement data shows a voltage dependent possible static efficiency enhancement of 25 to 40 percentage points in the 10 dB back-off region for a WCDMA signal. For the high voltages it is shown that the efficiency increase using supply modulation for high PAPR signals is greatly reduced. This is mainly a function of the narrower load-impedance matching range at higher supply voltages.

Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany


Power amplifiers, GaN-HEMT, supply modulation.