Antenna Array In-Situ Calibration through Source Reconstruction

Take the opportunity to develop a motivating career path in a multidisciplinary scientific community at the cutting edge of technological research at CEA Grenoble, as part of an internationally renowned R&D team in the field of antennas.

PhD Subject:
In many advanced applications (radar, direction finding, electromagnetic -EM- context monitoring), precise knowledge of antenna radiation rules the accuracy of processing (angular direction, polarization of received signals). The integration of miniature antennas on objects or vehicles of a few wavelengths largely impacts their radiation pattern. Particularly in low-frequency bands, antenna calibration is not sufficient to achieve the best levels of performance, let alone robustness over time.
The challenge of the proposed PhD is to be able to update the antenna array far-field calibration table in situ (i.e., in near-real time). To do this, the first part on EM analysis will be based on an exhaustive analysis of the equivalent modes/sources induced on the carrier structure via EM simulations, with the aim of extracting the modes present and their radiation. A second part dealing more with RF instrumentation will size and develop an array of spatial sampling probes installed on the structure of the carrier, which will measure the weightings of these modes in situ. Finally, the last part will hybridize the two previous parts in order to reconstruct the far-field radiation by weighting the simulated modes by the measured points.
During the final year, an experimental implementation will be used to validate the methodology and to analyze its performance.
This subject (EM simulation of antennas, EM analyses, RF measurements) will be supervised by an experienced team relying on exceptional tools and instruments (http://www.leti-cea.fr/cea-tech/leti/english/Pages/Applied-Research/Facilities/telecommunications-platform.aspx).

Applicant Profile: Engineer School or Master with major on Antenna, Electromagnetism, RF instrumentation

Laboratory: CEA Grenoble, heart of the French Alps
(http://www.youtube.com/watch?v=bCIcNJOzYZY)
The CEA is a major research organization working in the best interests of the French State, its economy and citizens. Thanks to its strong roots in fundamental research, it is able to provide tangible solutions to meet their needs in four key fields: Low-carbon energy (nuclear and renewable), Digital technology, Technology for medicine of the future, Defense and national security.
CEA Tech leverages a unique innovation-driven culture and unrivalled expertise to develop and disseminate new technologies for industry, effectively bridging the gap between the worlds of research and business.

Durable radially polatised tubular nanoreactors for catalysis

Rising energy demand and the need to reduce the use of fossil fuels to limit global warming have created an urgent need for clean energy collection technologies. One interesting solution is to use solar energy to produce fuels. Low-cost materials such as semiconductors have been the focus of numerous studies for photocatalytic reactions. Among them, 1D nanostructures are promising because of their interesting properties (high and accessible specific surface areas, confined environments, long-distance electron transport and facilitated charge separation). Imogolite, a natural hollow nanotubes clay, belongs to this category. Its particularity does not lies in its chemical composition (Al, O and Si) but in its intrinsic curvature, which induces a permanent polarization of the wall, effectively separating photo-induced charges. This nanotube belongs to a family sharing the same local structure with different curved morphologies (nanosphere and nanotile). In addition, several modifications of these materials are possible (coupling with metal nanoparticles, functionalization of the internal cavity), enabling their properties to be modulated. These materials are therefore good candidates as nanoreactors for photocatalytic reactions. So far, proof of concept (i.e. nanoreactor for photocatalytic reactions) has only been obtained for the nanotube form. The aim of this thesis is therefore to study the whole family (nanotube, nanosphere and nanotile, with various functionalizations) as nanoreactors for proton and CO2 reduction reactions triggered under illumination.

Design of a misalignment-robust, high-frequency GaN-based inductive power transmission system

The LAIC laboratory of CEA-LETI's Systems Department in Grenoble is specialized in the development of innovative electronic and mechatronic systems, taking into account challenges linked to energy recovery / management / transmission and sensor integration in a variety of environments. As part of the development of its R&D activities, the LAIC is offering a PhD thesis on wireless power transmission using GaN-based resonant inductive coupling.

Wireless power transmission technologies are booming, with applications in space, consumer electronics, medical, automotive and defense sectors. Power transmission technology using resonant inductive coupling appears to be the most promising in terms of near-field efficiency.

The proposed thesis will follow the development of a system including a fixed-coupling electromagnetic coupler and HF electronics based on a GaN transistor-based class-E topology. In this context, the aim of the thesis is to develop a system robust to coupler coil misalignment. The aim is to study, develop and test the performance of a new coupler and an adaptive drive electronics. The candidate will be required to develop analytical and numerical models to optimize the electronics, compare the performance of existing systems in the literature, and propose, develop and test the performance of innovative GaN-based topologies ensuring good robustness to electromagnetic coupling variation.

A multi-disciplinary profile with a focus on power electronics and physics is required for this thesis. In addition to a solid theoretical ground and strong simulation skills, the PhD student will need to be able to work as part of a team, with an aptitude for experimentation and an attraction for practical applications.

3D assembly of GaN power devices

The increase in electrical power density in everyday uses is the result of technological developments including materials and components. The first element to address is the use of a semiconductor material suitable for strong integration and capable of managing high power densities. Since the 2010s, wide bandgap semiconductors such as SiC or GaN have emerged in several applications and are causing a revolution in power electronics design, notably with an increase in the operating frequency and specific power of converters. Concerning Galium nitride (GaN), the increase in switching frequency was made possible thanks to the HEMT (High Electron Mobility Transistor).
The idea of ??this PhD topic is to work on a HEMT GaN cell assembly. The work will involve the an assembly of two components through a common electrode on their backsides in order, making it possible to reduce parasitic inductances and increase the operating frequency. The work will be based on simulation tools such as COMSOL and Synopsys. The thesis will be in collaboration with the GEEPS laboratory at CentraleSupelec and the University of Paris-Saclay.

Privacy-preserving federated learning over vertically partitioned data from heterogeneous participants

Federated learning enables multiple participants to collaboratively train a global model, without sharing their data, but only model parameters are exchanged between the participants and the server. In vertical federated learning (VFL), datasets of the participants share similar samples, but have different features. For instance, companies and institutions from different fields own data with different features of overlapping samples collaborate to solve a machine learning task. Though data are private, VFL remains vulnerable to attacks such as label and feature inference attacks. Various privacy measures (e.g., differential privacy, homomorphic encryption) have been investigated to prevent privacy leakage. Choosing the appropriate measures is a challenging task as it depends on the VLF architecture and the desired level of privacy (e.g., local models, intermediate results, learned models). The variability of each participant’s system can also result in high latency and asynchronous updates, affecting training efficiency and model effectiveness.

The aim of this thesis is to propose methods to enable privacy-preserving VFL, taking into account the heterogeneity of the participants. First, the candidate will study the architectures of VFL models and the privacy measures to propose privacy-preserving protocols for VFL. Second, the candidate will investigate the impacts of the heterogeneity of the participants’ system such as computation and communication resources to devise solutions to render the VFL protocols robust to such heterogeneity. Third, the trade-offs among effectiveness, privacy, and efficiency in VFL will be explored to propose a practical framework for adjusting the protocols according to the requirements of a given machine learning problem.

Advanced fully-depleted Silicon-on-insulator devices for Radio-Frequency applications

The PhD will be performed in the NEXTGEN project aimed at developing the next generation of Silicon-on-insulator devices. Our laboratory is driving the development of the RF active devices: this is a great opportunity to carry out fundamental research using state-of-the art processing equipment and characterization instruments while working in close collaboration with our industrial partners.

you will expected to engage in tasks encompassing:
- perform back-of the-envelope estimation of device properties and assess performace impact of technological choices
- Perform and/or analyze TCAD simulations to gain insight in the RF device behaviour
- data-mining on engineering measurements: grasp the relevant information and identify trends or correlations
- perform extensive periods of time in the lab to conduct or participate in on-wafer RF characterization champaign.
Based on you profile or expectations, above tasks may be dynamically rebalanced during the thesis.

Development and characterization of low temperature Cu-dielectric hybrid bonding

Cu-dielectric hybrid bonding is a technology that enables the assembly of components with very fine interconnection pitch, opening the path to new integrations for advanced applications such as High Performance Computing, Smart Imagers,… Leti has been engaged for more than 10 years in the development of this technology, in partnership with various industries and academies, to master smaller and smaller connection pitches (< 1µm), or to evaluate new techniques such as ‘die-to-wafer’ self-assembly. In this context, low temperature hybrid bonding would allow new integration routes notably for heterogeneous systems (III-V on CMOS,…) or for thermally sensitive components (colored resins, non-volatile memories,…).

The objective of this thesis is to develop and characterize Cu-dielectric hybrid assemblies performed at low temperature, from ambient to 250°C. A first part of the thesis will aim at identifying the dielectric materials that are relevant for the hybrid bonding technology (SiN, SiON, SiCN, …). The critical properties of these materials (permittivity, hygroscopy,…) will be measured and compared to the reference high temperature SiO2. In a second part, the selected dielectrics will be integrated in the ‘wafer-to-wafer’ hybrid bonding technology and each process step (damascene level, surface preparation, direct bonding) will be adapted as needed. The third part of the thesis will be dedicated to the electrical characterization and reliability tests of the obtained low temperature hybrid bonding.

Stocastic integrated power supplies based on emerging components

Context:
The widespread utilization of connected devices that process sensitive information necessitates the creation of new secure systems. The prevalent attack, referred to as power side-channel, involves the retrieval of encryption key information by analyzing the power consumption of the system. Integrating the system with its power supply management blocks can conceal the consumption of sensitive blocks, especially by utilizing various techniques to introduce randomized variations during power transfer. The CEA has wide experience in the design and testing of secure integrated circuits and it is exploring a new approach to DC-DC conversion that uses emerging devices available at CEA-Léti.
The work of the PhD researcher will be the following:
- Specification of integrated power supplies using switched-capacitor architecture.
- Study the circuit using emerging components and evaluate the improvement of its robustness against side channel attacks.
- Design of the integrated power supply in silicon technology.
- Performance and security characterization of the designed blocks and security primitives in
their whole.
The division of labor is 10% advanced study, 20% system architecture, 50% circuit design, 20% experimental measurement.

Olfactory technology (Qi - Wei): Chinese inspiration for ecotechnology

The specificity of Chinese technological thought has been the subject of recurrent philosophical debate since the early 20th century. This discussion highlights the originality of the sensory relationship with nature expressed in Chinese writing and culture. “Olfactory technology (Qi - Wei): a Chinese inspiration for ecotechnology” explores the hypothesis that a philosophy of technology, inspired by China but open to other cultures, can renew thinking on technology in its relationship to the environment, based on the paradigm of olfaction (Wei).
This approach is based on an analysis of traditional Chinese thought developed by contemporary Chinese philosophers, in particular Gong Huanan, and shows its influence on current Chinese technological thought. It also draws on the work of specialists in olfaction, as well as Western philosophers of technology, science and the imaginary (such as Gilbert Simondon, Gaston Bachelard and Dominique Lestel).
The primary scientific challenge is to restore the olfactory paradigm of Chinese technological thought in order to examine its relationship to the environment, and then to develop a transcultural ecotechnological reflection. In the light of these analyses, we will then reconsider the imaginaries of robotic and digital technologies in order to explore new avenues of innovation. Finally, from a science fiction prototyping perspective, speculative fictions will extend the analysis by examining the impact of imaginable technologies based on the olfactory paradigm.

Laser Fault Injection Physical Modelling in FD-SOI technologies: toward security at standard cells level on FD-SOI 10 nm node

The cybersecurity of our infrastructures is at the very heart in the digital transition on-going, and security must be ensured throughout the entire chain. At the root of trust lies the hardware, integrated circuits providing essential functions for the integrity, confidentiality and availability of processed information.
But hardware is vulnerable to physical attacks, and defence has to be organised. Among these attacks, some are more tightly coupled to the physical characteristics of the silicon technologies. An attack using a pulsed laser in the near infrared is one of them and is the most powerful in terms of accuracy and repeatability. Components must therefore be protected against this threat.
As the FD-SOI is now widely deployed in embedded systems (health, automotive, connectivity, banking, smart industry, identity, etc.) where security is required. FD-SOI technologies have promising security properties as being studied as less sensitive to a laser fault attack. But while the effect of a laser fault attack in traditional bulk technologies is well handled, deeper studies on the sensitivity of FD-SOI technologies has to be done in order to reach a comprehensive model. Indeed, the path to security in hardware comes with the modelling of the vulnerabilities, at the transistor level and extend it up to the standard cells level (inverter, NAND, NOR, Flip-Flop) and SRAM. First a TCAD simulation will be used for a deeper investigation on the effect of a laser pulse on a FD-SOI transistor. A compact model of an FD-SOI transistor under laser pulse will be deduced from this physical modelling phase. This compact model will then be injected into various standard cell designs, for two different objectives: a/ to bring the modelling of the effect of a laser shot to the level of standard cell design (where the analog behaviour of a photocurrent becomes digital) b/ to propose standard cell designs in FD-SOI 10nm technology, intrinsically secure against laser pulse injection. Experimental data (existing and generated by the PhD student) will be used to validate the models at different stages (transistor, standard cells and more complex circuits on ASIC).
Ce sujet de thèse est interdisciplinaire, entre conception microélectronique, simulation TCAD et simulation SPICE, tests de sécurité des systèmes embarqués. Le candidat sera en contact/encadré avec deux équipes de recherche; conception microélectronique , simulation TCAD et sécurité des systèmes embarqués.

Contacts: romain.wacquez@cea.fr, jean-frederic.christmann@cea.fr, sebastien.martinie@cea.fr

Top