<p>Gallium Nitride based devices due to their inherent material properties are considered as one of the most promising devices to realize high power, high frequency transistors with lower power consumption in next-generation applications. Although the technology has been studied since early 1970s, there is still a vast room and expectations in its yet unachieved findings. In present work the GaN technology is explored and state-of-the-art studies of GaN based HEMTs and their application in MMICs are presented. Different designs are presented and evaluated and the results are reported. In particular the HEMT performance is studied in terms of DC in addition to large signal conditions, where the device’s performance becomes function of power levels it is driven with. The peculiarities and challenges of building an automated Load-Pull setup are outlined and analysis for further improvements is presented.</p>

Gallium Nitride based devices due to their inherent material properties are considered as one of the most promising devices to realize high power, high frequency transistors with lower power consumption in next-generation applications. Although the technology has been studied since early 1970s, there is still a vast room and expectations in its yet unachieved findings. In present work the GaN technology is explored and state-of-the-art studies of GaN based HEMTs and their application in MMICs are presented. Different designs are presented and evaluated and the results are reported. In particular the HEMT performance is studied in terms of DC in addition to large signal conditions, where the device’s performance becomes function of power levels it is driven with. The peculiarities and challenges of building an automated Load-Pull setup are outlined and analysis for further improvements is presented.

La technologie Nitrure de Gallium s’impose actuellement comme le candidat idéal pour les applications de forte Puissance en gamme d’ondes millimétriques. Les caractéristiques de ce matériau le prédisposent à un fonctionnement à haute tension sans sacrifier la montée en fréquence, illustrées par son champ de claquage et sa vitesse de saturation des électrons élevés. Ces travaux de recherche s’inscrivent, dans un premier temps, dans le développement d’un banc de mesures permettant la caractérisation « grand signal », dite LoadPull dans la bande Ka et Q, en mode continu et impulsionnel de cette technologie émergente. En effet, la forte densité de puissance qu’est capable de générer la technologie GaN a rendu le développement de ce banc indispensable et relativement unique. Par ailleurs, cette étude s’est focalisée, dans la caractérisation de plusieurs filières innovantes qui ont mis en évidence des performances à l’état de l’art, avec un rendement en puissance ajoutée PAE de 46.3% associée à une densité de puissance de 4.5W/mm obtenue pour une fréquence d’opération de 40 GHz en mode continu. Enfin, ces travaux de thèse ont permis de générer la conception et la réalisation de deux amplificateurs de puissance en technologie GaN sur substrat silicium (basée sur la filière industrielle OMMIC) en bande Ka, représentant la finalité d’une démarche cohérente de l’étude de transistors en technologie GaN à la réalisation de circuits de type MMIC. Ces deux amplificateurs ont été conçus pour des objectifs biens précis : combiner puissance élevée et rendement PAE élevé et repousser les limites en termes de largeur de bande. / Gallium Nitride (GaN) technology is now the ideal candidate for high power applications in the millimeter wave range. The characteristics of this material enable high voltage operation at high frequency, as illustrated by its breakdown field and high electron saturation velocity. This research work has initially allowed the development of a test bench capable of "Large Signal" characterization, called LoadPull up to Q band, in continuous-wave and pulsed mode of this emerging technology. Indeed, the high power density generated by the GaN technology has made the development of this bench unavoidable and relatively unique. In addition, this study has focused on the characterization of several innovative types of devices that have demonstrated state-of-the-art performance, with a power added efficiency (PAE) above 46% associated to a power density of 4.5 W/mm obtained for an operating frequency of 40 GHz in continuous-wave. Finally, this work aimed the design and fabrication of two power amplifiers on silicon substrate (based on the industrial OMMIC technology) in the Ka-band, showing the possibility of achieving MMIC type circuits from advanced GaN transistors technology. These two amplifiers were designed for specific purposes: combining high power and high PAE performance and pushing bandwidth limits.