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Limoges, France

Gasseling T.,AMCAD Engineering
Microwave Journal | Year: 2012

The main topics involved with model extraction of compact transistor models such as wide band gap (WBG) field effect transistors (FET) such as gallium nitride (GaN) FETs are discussed. It is necessary to determine the transistor's thermal impedance in order to complete an electro-thermal model that can dynamically predict performance as a function of device temperature and self-heating. The thermal circuit provides the equivalent transistor junction temperature as a function of DC power and is used in the various sub-circuit models that are linked to voltages, currents and temperatures. Pulsed IV measurements are used to study the individual trapping effects and differentiate between surface trapping (gate-lag) and buffer trapping (drain-lag). In addition to the parameters obtained from a frequency- domain system, time domain load-pull allows for the measurement of voltage and current waveforms and load lines. Source

Dellier S.,AMCAD Engineering | Dehaene T.,Syrlinks | Peragin E.,French National Center for Space Studies
PAWR 2014 - Proceedings: 2014 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications | Year: 2014

This paper describes the development of a high-efficiency S-band power amplifier (PA) with power flexibility, based on packaged GaN devices. This amplifier aims to demonstrate the highest power added efficiency (PAE) for a flexible output power from 1 W to 10 W. The approach consists in selecting the suited components of the shelf (COTS), and then in performing comprehensive power characterizations of these devices. The modeling process used enables to design the two stages amplifier with very good predictions of the manufactured PA. The obtained results with an efficiency above 60% for the full range of adjustable RF power between 1 and 10W, are very promising for use in future space applications. © 2014 IEEE. Source

Charbonniaud C.,AMCAD Engineering | Gasseling T.,AMCAD Engineering
2015 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems, COMCAS 2015 | Year: 2015

This paper presents a simple methodology to observe the RF waveforms at the drain source current reference plane of the transistor, without using a complete nonlinear model. The aim is to allow Power Amplifier designers starting their work using VNA based harmonic and time domain load pull measurements, and S parameter measurements. The later measurements will be used to extract a linear model first. Then the parameters of the linear model will be used to deembed the load pull measurements directly at the voltage controlled current source plane, in order to enable waveform engineering. Because of the well know theoretic conditions that enable optimum efficiency, this methodology can also be used to avoid time consuming multi-harmonic load pull measurements. Harmonic impedances can be defined accordingly to the knowledge of the operating class addressed, while load pull optimization can be addressed to refine the fundamental matching only. © 2015 IEEE. Source

A method for determining optimal source impedance at the input of a device under testing (DUT) in a measurement bench, includes the steps of calibrating a source pull type bench as a measurement bench, adjusting a load impedance and continuous bias of the DUT, generating an electric power signal by the source and injected in the DUT, acquiring input impedances of the DUT and corresponding gain performances.

Demenitroux W.,AMCAD Engineering | Demenitroux W.,French National Center for Scientific Research | Maziere C.,AMCAD Engineering | Gasseling T.,AMCAD Engineering | And 3 more authors.
European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings - European Microwave Conference, EuMC 2010 | Year: 2010

This paper presents a new macro modeling methodology for solid-state amplifiers (SSAs) or packaged transistors used in communication systems. The model topology is based on the principle of the harmonic superposition recently introduced by the Agilent X-parameters(TM) combined with dynamic Volterra theory. The model results on a Multi-harmonics Bilateral model which handles short-term memory effects. In this work, the behavioral model developed was extracted from time domain load pull measurement performed on one amplifier. Then, the model was used for the simulation of the amplifier's response using a two tones and a CW signal under moderate mismatched load operating conditions. © 2010 EuMA. Source

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