Pulsed gate bias control of GaN HEMTs to improve pulse-to-pulse stability in radar applications

International audienceA significant improvement is demonstrated in the measured pulse-to-pulse stability of an S-band 6 W GaN high electron mobility transistor (HEMT) power amplifier by generating an appropriate pulse of the gate bias and thus a warm-up drain current just before each radio-frequency (RF) pulse of a periodic and coherent radar burst. The amplitude and the width of this gate bias pulse preceding each periodic RF pulse of the burst are experimentally varied to investigate the trade-off between the improvement of pulse-to-pulse stability and the total power-added efficiency. Finally, this technique of synchronised warm-up gate bias pulse demonstrated a 10 dB improvement of measured amplitude pulse-to-pulse stabilities to meet the critical stability requirement below −55 dB for the RF power amplifier

Near-field measurement of microwave active devices

A completely new near field mapping system based on micro monopole antenna has been developed in order to determine the electric near-field at the surface of MMIC. The possibilities of this innovative experimental setup are shown by 2D mapping of a bend 5 line deposited on GaAs substrate and a coupled-line filter on Duroid 6002. These are supported by 3D electromagnetic simulations. We finally give some results obtained on a real MMIC with a medium resolution of 50µm. The industrial applications are clearly the reliability issues of microwave power devices but also a new tool for MMIC designers. The knowledge of radiated near field will also contribute to optimize the packaging of microwave functions

Welcome to the 16th European Radar Conference, EuRAD 2019

Présentation et organisation conférence EURAD 2019International audienceProvides a schedule of conference events and a listing of which papers were presented in each sessio

Measurement of Self-Heating Temperature in AlGaN/GaN HEMTs by Using Cerium Oxide Micro-Raman Thermometers

International audienc

A 5000h RF life test on 330 W RF-LDMOS transistors for radars applications

International audienc

A 5000h RF life test on 330 W RF-LDMOS transistors for radars applications

International audienc

Thermal management of power HBT inpulsed operating mode

We focus this paperon the improvement of the thermal management of power transistor based on the InGaP/GaAsHBT technology and specially for pulsed mode application Applied to very HB Thigh power transistor, from 10 W to 3W, respectively for L to Ku bands radar applications, a specific study has been done to suggest new opportunities if we take into account the transientor dynamic behavior of the transistor in pulse operating mode. From very short pulse (1µs)to very long pulse (≈1ms)a analysis has been performed with as a consequence a strong improvement of thermal impedance(Zth) through specific designs of the thermal shunt (material–shape)present at the front side. We chose to develop the concept of “thermal sponge” on power HBT transistor acting as avery efficient thermal capacitance to suppress thermal variation inside the pulse and improving as a consequence the CW thermal resistance. Two approaches have been compared: the first one with the support of very thick metal growth directly on the thin gold thermal shunt, the second one with a very small part of diamond substrate directly on top the same thermal shunt. As a conclusion, for long pulse application greater than 200µ sup to 1ms, the diamond approach gives superior result with 30%of improvement on the temperature rising

Characterization and modeling of hot carrier injection in LDMOS for L-band radar application

International audienc

Mise en oeuvre d'un boîtier d'un transistor GaN optimisé haut rendement (70% PAE) et large bande (1GHz) en bande S

National audienceCe papier expose une nouvelle méthodologie doptimisation dun boîtier de transistor GaN pour la conception damplificateur très haut rendement et large bande, fournissant 70% de PAE sur 1GHz en bande S. Ces performances sont obtenues en optimisant uniquement les impédances à la fréquence fondamentale. En effet, le contrôle des impédances aux fréquences harmoniques du transistor est réalisé lors du câblage de la puce dans son boîtier. Des mesures load-pull à 3.2GHz ont démontré que la PAE atteint 72% en optimisant uniquement le fondamental, soit 8 points de PAE en plus par rapport à un transistor sous pointes. De plus, les variations de la PAE à lharmonique 2 sont de 6 points seulement ce qui assure un fonctionnement haut rendement du transistor en boîtier