ED Sciences Physiques et de l'Ingénieur
Definition and implementation of a multiphase receiver for automotive radar applications
by Salime BOUMLIK (Laboratoire de l'Intégration du Matériau au Système)
The defense will take place at 10h00 - Amphi JP. DOM IMS - Laboratoire de l'Intégration du Matériau au Système 351 Cours de la Libération, 33405 Talence Cedex
in front of the jury composed of
- Thierry TARIS - Professeur - Bordeaux-INP/Laboratoire IMS - Directeur de these
- Baudouin MARTINEAU - Docteur - CEA Leti - Rapporteur
- Florence PODEVIN - Professeure - Grenoble INP/Laboratoire TIMA - Rapporteur
- Jean-Baptiste BEGUERET - Professeur - Université de Bordeaux/Laboratoire IMS - Examinateur
- Cristian PAVAO MOREIRA - Docteur - NXP Semiconductors - Examinateur
Automotive FMCW radars are expected to proliferate in future vehicles, raising concerns about the ability of current receiver architectures to operate reliably in dense spectral environments where bumper reflections and external interferences impose severe linearity constraints on the mmWave front-end. Existing mitigation techniques operate after the down-converter, leaving the front-end fully exposed, while technology scaling limits linearity improvements of mmWave circuits without degrading gain or noise figure. This work proposes a novel receiver architecture integrating a reconfigurable mmWave N-path filter at the front-end, enabling early-stage attenuation of strong interferers and thereby fundamentally relaxing mixer linearity constraints. A thorough and quantitative architectural analysis was conducted to evaluate gain distribution, noise contributions, and linearity margins, demonstrating that the proposed solution enables a more favorable trade-off between sensitivity and robustness to interferences. The N-path filter inherently features a dynamically reconfigurable center frequency and is thus compatible with FMCW modulation. Placed after a first LNA, it provides additional out-of-band linearity margin that enables the introduction of a second LNA stage to improve noise figure without violating linearity requirements. This work further delivers a comprehensive investigation of mmWave N-path filters in CMOS 28nm bulk technology, combining analytical modeling and a two-state switch representation that captures parasitic effects, path overlapping, and compression mechanisms, providing deep insight into design trade-offs at 79 GHz. Both 2-path and 4-path implementations were analyzed, designed, and validated, demonstrating comparable insertion loss (~11 dB) and noise figure (~12 dB) in post-layout simulations, while revealing different sensitivities to parasitics, LO constraints and process variations, thereby providing a comprehensive and experimentally grounded understanding of the associated design trade-offs. A mmWave quadrature LO generation circuit based on inverter stages was developed and validated to drive the 4-path filter, addressing the challenges of signal amplitude, duty cycle, and phase integrity at 79 GHz. A proof-of-concept test chip integrating two receiver front-ends, including a reference architecture and a front-end incorporating the mmWave N-path filter, was implemented and characterized, representing a significant experimental effort. Measurements experimentally demonstrate N-path filtering across the 76–81 GHz radar band with ~15 MHz bandwidth and very high quality factor, representing the first reported implementation of such filtering at mmWave radar frequencies. Measured results confirm the predicted behavior, including improved out-of-band linearity, validating the proposed architecture and its ability to enable higher mmWave front-end gain without compromising linearity constraints. The consistency between architectural analysis, circuit-level modeling, and experimental validation further strengthens the relevance of the proposed solution. Overall, this work establishes N-path filtering as a powerful architectural lever to enhance mmWave receiver performance under stringent interference conditions and opens new perspectives for integrated filtering techniques, including N-path-based filtering LNAs and advanced front-end co-design strategies.
Development of Hybrid Numerical Methods for the Diffraction of Ultrasonic Waves by Features on the Surface of Stratified Structures, and Application in Non-Destructive Testing.
by Romain KUBECKI (I2M - Institut de Mécanique et d'Ingénierie de Bordeaux)
The defense will take place at 10h00 - Salle 003, Amphithéâtre 1 Campus Peixotto, Bâtiments A9.a et A9.b RDC, 33400, Talence
in front of the jury composed of
- Marc DESCHAMPS - Directeur de recherche - CNRS, I2M, UMR 5295 - Directeur de these
- Tony VALIER BRASIER - Maître de conférences - Sorbonne Université, Institut Jean Le Rond d'Alembert - Rapporteur
- Marc BONNET - Directeur de recherche - CNRS, POEMS, UMR 7231 - CoDirecteur de these
- Julien DIAZ - Directeur de recherche - Université de Pau - Rapporteur
- Mohamed ICHCHOU - Professeur des universités - Centrale Lyon - Examinateur
- Édouard DELMADENT - Ingénieur de recherche - CEA Saclay - Examinateur
This study aims to simulate experiments in Non Destructive Testing (NDT), Structural Health Monitoring (SHM), and imaging of an arbitrarily large size layered structure. That structure supports features of small size (stiffeners, sensors, other multi-physical entities) which create waves or disturb their propagation. The objective is to quantify their impact within the structure. The latter being large, standard 3D numerical methods, such as the Finite Element method (FEM), are too computationally prohibitive, which motivates the use of a hybrid approach. This approach combines the finite element method, well suited for modeling local objects, with a semi-analytical Fourier-Fourier-Laplace (FFL) method, which requires that structures are invariant along the direction of layers (plane or tubular geometry). Their coupling relies on an iterative Domain Decomposition Method (DDM){:} at each iteration, two local subproblems are independently solved with Robin-type boundary conditions depending on the solution from the previous iteration in both subdomains. However, the use of the FFL method introduces several difficulties. Firstly, the type of boundary conditions applied to the structure can vary on a single boundary. Secondly, the finite element solution does not necessarily satisfy the Nyquist--Shannon criterion. As a consequence, a specific data exchange protocol between the FE method and FFL approach must be established. The convergence of the DDM iterations is first established and then implemented numerically with both subdomains discretized using the FEM. Then, the problem within the structure is reformulated as an integral equation to handle the non-uniform boundary conditions. Finally, a data exchange protocol is developed to ensure communication between the subproblems.
ED Sociétés, Politique, Santé Publique
The Need to Reduce Waste: When Daily Environmental Efforts Become a Moral Imperative. The Adoption of a Local Zero-Waste Policy in Gironde.
by Maxence MAUTRAY (Centre Emile Durkheim)
The defense will take place at 14h00 - Amphithéâtre E, Bâtiment E, Campus Victoire. 3ter Pl. de la Victoire, 33000 Bordeaux.
in front of the jury composed of
- Olivier CHADOIN - Professeur des universités - Université de Bordeaux - Directeur de these
- Rémi BARBIER - Professeur des universités - GESTE, ENGES Strasbourg - Rapporteur
- Delphine CORTEEL - Professeure des universités - CITERES, Université de Tours - Rapporteur
- Valérie DELDRèVE - Directrice de recherche - ETTIS, INRAE Bordeaux - Examinateur
- Agnès JEANJEAN - Professeure des universités - LAPCOS, Université Côte d'Azur - Examinateur
- Baptiste MONSAINGEON - Maître de conférences - CRIEG-REGARDS, Université de Reims Champagne-Ardenne - Examinateur
This thesis examines the reception of a local “zero waste” policy implemented since 2019 by a public household waste service in a rural and peri-urban area of Gironde, France. In a context marked by the growing prominence of environmental policies, which increasingly target individuals' everyday practices, it investigates how the implementation of such a policy transforms residents' daily lives. Drawing on a mixed-methods approach (interviews, ethnographic observations, a questionnaire, institutional documents, and local press), the study shows that the institutional mobilisation of the population generates an everyday environmental effort, opens up a space of comparison between individuals, and, as a result, gives rise to controversies and feelings of injustice. Based on three years of embedded fieldwork within the public service in charge of the reform, the analysis demonstrates that this process of everyday “ecologisation” cannot be reduced to a matter of individual behaviours or motivations. The routinisation of waste reduction practices (bulk purchasing, composting, reuse, etc.) depends closely on constraints shaping lifestyles —economic, temporal, and organisational — as well as on material living conditions. The mobilisation of the population, through both the diffusion of zero-waste prescriptions and the reorganisation of the service (ending door-to-door collection, introducing incentive-based pricing), produces an unevenly distributed environmental effort. This injunction is accompanied by the diffusion of a normative framework encouraging individuals to assess their own practices. In the absence of concrete indicators of waste production, this process opens up a space of social comparison, leading to the formation of a moral economy of zero waste, within which individuals position themselves, adjust their level of engagement, and formulate ordinary judgments about others' practices, even without explicit adherence to the zero-waste ethos. When these dynamics take material form through concrete transformations of the public service—particularly the shift from door-to-door collection to drop-off systems—they give rise to more visible forms of politicisation. The reform becomes an object of controversy, involving residents, elected officials, and the institution, and circulating across multiple arenas (media, political, and legal). It leads individuals to assess the legitimacy of the policy in light of the effort it requires and the principles that justify it, generating feelings of injustice and criticisms directed both at its concrete implementation and at the normative foundations of environmental public action. This research thus shows that waste constitutes a key analytical entry point for understanding contemporary transformations of environmental public action. By focusing on its most ordinary effects, it uncovers the mechanisms through which environmental policies reconfigure everyday life, produce normative expectations, and render visible social inequalities requalified in environmental terms. It demonstrates that such policies do not merely regulate behaviour, but actively reshape the boundaries between what is perceived as just and unjust at the very heart of everyday life.