Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Engineering science >> Electromagnetism - Electrical engineering
2 proposition(s).

Compact and ultra-wideband antenna arrays in Ka-band

Département Systèmes

Laboratoire Antennes, Propagation, Couplage Inductif

01-09-2019

SL-DRT-19-0386

loic.marnat@cea.fr

Millimeter-wave communication (e.g. 5G) or radar (e.g. automobile) systems require directive antennas to compensate for transmission losses and ultra-wideband antennas to ensure, depending on the targeted application, a high data rate or a fine resolution. Agility of radiation pattern is thus a key point. Array antennas offer undeniable advantages and come with a tradeoff between the number of radiating elements and the number of active circuit to achieve the performance required in terms of beam focalization and radiated power (for a form factor defined by the targeted system). However, classical design rules associated to typical array elements arrangement can be show stopper for the antenna integration in some applications and typically lead to limited operating band and scanning range. The aim of the thesis is to get rid of these limitations and to design a seamless compact phased array antenna while ensuring outstanding performance in terms of band of operation and scanning capabilities. To do so, studies will focus on tightly coupled miniature elements put in an array fashion. Four main steps will be needed to understand and model such compact array antennas: - State of the art on tightly coupled and ultra-wideband antenna arrays, - Theoretical study describing the coupled elements behavior and the law governing the coupling between them in dense arrays, - Design if a compact array based on miniature and ultra-wideband coupled elements. Technology compatible with seamless and low cost solutions will be preferred. - Active Ka-band prototype will be realized and measured. The thesis will lead to a compact active millimeter-wave phased array prototype competitive as compared to actual state of the art. These studies will pave the way to the use of phased array in applications with complex and compact environments such as 5G terminal and access point or automotive radars and even for advanced satellite antennas.

New intelligent GaN power chips : Study and implementation into an industrial application

Département Systèmes

Laboratoire Electronique Energie et Puissance

01-10-2019

SL-DRT-19-0832

leo.sterna@cea.fr

The new HEMT GaN transistors emergence in power electronics opens up many possibilities for improving power converters performances: increase power density and efficiency, high temperature operation. In order to make the GaN transistors implementation reliable in a converter environment, the monitoring of the various signals at the terminals of the component is essential. The HEMT GaN transistors instantaneous current measurement remains a problem, and not so much studied. CEA Leti has a technology and specific components allowing the measurement of instantaneous current with a very good dynamic. This thesis proposes to study and implement current mirror measurement circuits for HEMT GaN power transistors. The doctoral student will reflect on the possible applications of the current mirror sensor that can protect the transistor current, or make possible the dynamic control of the switching. This monitoring function will be integrated within a specific driver circuit, the final objective of the thesis being to propose a driver circuit with integrated current sensor and control feedback on the transistor. The PhD student will be hosted at L2EP, within the power electronic team. Scientific supervision will be provided by researchers from the G2ELab university laboratory in co-supervision with CEA Leti's research engineers. The doctoral student will evolve in an innovative and multidisciplinary environment.

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