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PhD defense of Younes BOUJMAD

Published on January 21, 2021
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PhD Defense February 4, 2021 | Access map
Defense of doctoral thesis of  Younes BOUJMAD, for the University Grenoble Alpes, speciality  " OPTIC & RADIOFREQUENCIES ", entitled:
Amphitheater  Pôle Montagne, Room 30Campus scientifique USMB
73376, le Bourget du Lac Cédex

« Design, characterization and realization of a 10GBASE-T Ethernet contact integrating 4 differential pairs »



Thursday,   February 4,2021 at 9:45 am
Keywords :     
Electromagnetic modeling,HF design,Octomax contact,Category 6A,Characterization of dielectric materials,Ethernet connector

Le proThe research project involves designing, modeling, and characterizing new contacts called “Octomax” for Ethernet applications at very high speeds in harsh environments, and specified at a rate of 10 Gbits/s.
In a harsh environment, an electrical contact consists of a standard metal envelope called “external contact”, a metal pins called “inner contacts” and an insulating part made of thermoplastic dielectric material. These contacts are intended to be mounted in a series of 38999 connectors thus meeting the MIL-DTL-38999 standard and will therefore have to endure many restrictive tests (electric, mechanical, vibratory, thermal).
The Octomax are composed of eight interior contacts into the same Quadrax envelope (Quadrax is a previous generation of contact with four pins). The increase data rates pass through increasing the number of pins, but also optimizing the electrical performance on a wider bandwidth. The signal integrity parameters are studied through a complete frequency analysis of the Octomax contact. A methodology for calculating three normative criteria (Return loss, Insertion Loss and NEXT) is proposed and Octomax contacts are then optimized to meet the templates of category 6A hardware.
The impedance mismatch, the level of coupling between differential pairs and the assembly time of an Octomax are then identified as three blocking points when studying a first prototype. The solution envisaged is to design a contact whose shielding is molded by thermo-injection in a single piece with the dielectric. In addition, a complex method of extracting dielectric permittivity allowed the study of polymers and the choice of a material from several candidates. The dielectric part was then the subject of optimization work to respond to the constraints of impedance matching and the constraints of mechanical realization (machining and thermoforming.
The various stages of the project have resulted in the industrialization of an Octomax 10 Gbits/s contact that meets the hardware templates of category 6A and therefore specified at a speed of 10 Gbits/s per 100 m of Ethernet cable (standard 10GBASE-T).

Jury members :
  • Bernard FLECHET -  Professor, University of Savoie Mont-Blanc : Supervisor
  • Sonia BEN DHIA DELMAS - Professor, INSA Toulouse : Examiner
  • Cédric BERMOND - Associate Professor, University of Savoie Mont Blanc : Examiner
  • Philippe ARTILLAN - Associate Professor , University of Savoie Mont Blanc : Examiner
  • Valérie MADRANGEAS - Professor, University of Limoges : Reviewer
  • Tchanguiz RAZBAN - Professor, University of  Nantes :  Reviewer

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Thesis prepared at the laboratory : UMR 5130 - Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'hyperfréquences et de caractérisation, supervised by  Bernard FLECHET, supervisor.

Date of update January 21, 2021

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