Characterization of GaN HEMT Low-Frequency Dispersion Through a Multiharmonic Measurement System

Theoretical consideration on harmonic manipulated amplifiers based on experimental data

“…1 [7] has been used to fully characterize the behavior of a 0.5-µm 10x100-µm GaN HEMT device from SELEX-ES (Italy). The device was biased at V d0 = 22 V and I d0 = 50 mA, which corresponds to about 8% of maximum current I max (i.e., 700 mA), thus resulting in a deep Class-AB condition.…”

“…The aim is investigating and comparing the electrical performance of the device under two different classes of 978-1-4673-6496-6/15/$31.00 ©2015 IEEE operation exploiting harmonic manipulation, i.e., TL [2] and Class F [3], in order to experimentally verify the theoretical data predicted by simplified models and, at the same time, give a validation of the low-frequency methodology used for tests. The measurement setup is based on multi-harmonic excitations [7], [8]: a f 0 = 2 MHz fundamental frequency is conveniently adopted in order to operate above the cut-off of the low-frequency dispersive effects [9], and to neglect the transistor linear and nonlinear reactive phenomena. Such a setup operates as a vector multi-harmonic active load-pull system: by controlling the amplitude of gate and drain incident waveforms and their relative phase, different load terminations can be arbitrarily synthesized at the fundamental and harmonic frequencies for a given bias condition.…”

“…In this work, by using a low-frequency multi-harmonic load-pull setup [7], [8], harmonic manipulation at the currentgenerator plane is applied to a GaN transistor, and evaluated in different loading conditions, namely Tuned Load (TL) and Class F [2], [3]. In particular, on the basis of experimental data, we demonstrate the effectiveness of the theoretical approaches and highlight the importance of synthesizing the required harmonic impedances at the correct reference plane.…”

Transistor vector load-pull characterization for millimeter-wave power amplifier design

“…The aim of this work is to obtain information about the LP contours at millimeter-wave frequencies by exploiting an active time-domain LP measurement system working at few megahertz [4], jointly with frequency-and bias-dependent small-signal S-parameter measurements [7].…”

“…In this paper, a recently proposed technique [3], which is based on basic concepts of ED modeling and low-frequency (LF) device characterization under nonlinear operation [4], has been exploited for the millimeter-wave characterization of a 0.15-µm GaAs pHEMT under class-A operation. The proposed technique, by providing the waveforms at the current generator plane of an ED, allows to directly monitor the device dispersive behavior and reliability issues [5][6].…”