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

PhD : selection by topics

Technological challenges >> Communication networks, IOT, radiofrequencies and antennas
7 proposition(s).

5G mmW integrated BiDirectional TRX for hybrid and digital beamforming system

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0478

baudouin.martineau@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

This thesis addresses the topic of compact, low-cost millimeter wave transceiver in the context of the new coming 5G FR2. Indeed, a considerable number of chips and an area-efficient design will be necessary for hybrid and digital MIMO beamforming. However, conventional transceiver designs use switch-based bidirectional approach with one Tx and one Rx working alternatively in time duplex. For this reason, bi-directional transceiver completely sharing amplifiers and matching networks between the transmitter and the receiver is proposed. Additionally, bidirectional phase shifter, quadrature mixer and baseband amplifier will be studied and design offering a complete solution for hybrid and digital beamforming architecture. The thesis study will cover the architecture, the design and the measurement of such blocs in standalone and the full transceiver. The awaited innovation will encompass several aspect: bidirectional front-end compatible with hybrid configuration, mmW digital beamforming compatible, LO multiplication and local quadrature generation, CMOS SOI process. This phd research will give the opportunity to work in cross-scientific disciplinary from millimeter wave to baseband design and transceiver system architecture offering a very large panel of experiences and competencies. The thesis will take place in the CEA Leti institute under the supervision of Mr Martineau Dr and Mr Belot Hab. The publication in journals and international conferences will be encouraged and facilitated.

Download the offer (.zip)

Optomechanical reference oscillators

Département Composants Silicium (LETI)

Laboratoire Composants Micro-Capteurs

01-09-2020

SL-DRT-20-0592

marc.sansaperna@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

Clocks (reference oscillators) are ubiquitous elements in electronic circuits. The arrival of new technologies such as 5G or autonomous vehicles requires a level of performance that is not attainable by commercial clock technologies. One of the most promising routes to improve performance is the development of clocks based on micro-electromechanical (MEMS) resonators at high frequency (1-5 GHz, tens of GHz in the future). However, it is challenging to build high-performance MEMS resonators in the GHz range, mainly due to the difficulty of detecting their minuscule vibration amplitudes. Recently several groups have demonstrated the possibility of building optomechanical devices in piezoelectric materials. This technology, which was confined to fundamental studies, is now mature enough to evolve towards applications, and solves many of the difficulties involved in the implementation of MEMS clocks in the GHz range. The objective of the thesis is to develop a MEMS clock based on this novel optomechanical technology. The thesis will take place in the Microsensors Laboratory of the CEA-Leti, in collaboration with the RF Components Laboratory. The Leti is a pioneer in the implementation of on-chip optomechanical and piezoelectric resonators. The PhD student will work in collaboration with Leti Engineers to design the MEMS resonators and their fabrication process, based on an analytical study and finite-element simulations. Then, the student will have the opportunity to contribute to the fabrication of the devices in clean room. Finally, the student will characterize them in the Leti's laboratories, to extract their performance and implement a first demonstrator of MEMS clock.

Download the offer (.zip)

Resonators and devices based on elastic waves obtained through the hybridization of surface and bulk waves

Département Composants Silicium (LETI)

Laboratoire Composants Radiofréquences

01-09-2020

SL-DRT-20-0668

alexandre.reinhardt@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

Bulk or surface elastic wave devices are currently an enabling technology for radiofrequency emission/reception circuits used in mobile phones. Since, at constant frequency, the wavelength of elastic wave is close to 100,000 times smaller than electromagnetic wavelengths, the treatment of a signal carried by elastic waves instead of an electrical signal offers a tremendous miniaturization. With the increase in frequency bands operated simultaneously by each single mobile phone, requirements brought onto radiofrequency filters become more and more stringent. This motivates the research on new types of components exploiting new elastic waves. Conventional technologies rely on bulk acoustic waves (BAW) or surface acoustic waves (SAW) propagating respectively along the thickness or the surface of a piezoelectric material. Such kind of materials offer the possibility to couple electric signals into elastic waves, and conversely. In the last few years, a new kind of propagation mode, called "hybrid SAW/BAW" has been proposed, based on the excitation of waves by a periodic array of piezoelectric stubs. First realizations have been proposed, but their properties are not yet fully determined. This PhD subject focuses therefore on the study of the potentialities offered by these new kinds of modes. On one hand, the properties of such waves are strongly related to the combination of piezolectric material, of the nature of the substrate, on their respective crystal orientations as well as on the geometric dimensions of the piezoelectric stubs. The candidate will therefore investigate the design space in order to reveal what performances can be expected from such structures and optimise their design towards applications such as RF filters or time references, ideally for applications above 3 GHz. This work will leverage the simulation models available at CEA-LETI and those developped by the FrecNSys company. A second part of the PhD is expected also to explore more fundamental possibilites opened by these modes arising from the coupling between elastic surface waves and a periodic array of electrically active structures. Such periodic structures belong to the broader range of so-called elastic metamaterials, which offer unusual propagation properties such as frequency ranges in which wave propagation is forbidden, artificial slowing of waves, strong confinement or nonreciprocal propagation. Since active structures are involved, additional interesting effects may be explored. The candidate will leverage the expertise on elastic metamaterials brought by the acoustic department of ISEN. Eventually, an experimental part will be devoted to the proposition of designs to be implemented in the clean rooms of CEA-LETI and participation to the technological developments. The goal is here to assess the exprimental feasibility of such structures.

Download the offer (.zip)

Innovative mmw receivers architectures and circuits for resilient modulation schemes

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0689

joseluis.gonzalezjimenez@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

Existing telecommunication and data communication networks are evolving towards extremelly high capacity and data-rate connections that will require innovative transceiver architectures. For wireless data links, 5G and beyond 5G systems will be required in the next 5 to 10 years abel to provide 100Gb/s or higher data rates by efficiently using the wide spectrum available at millimeter-wave(mmW) frequencies. Traditionnal transceiver architecture that have been used in the past may result too power consuming or simply not performant enough to respond to this challenge. The LETI research institute has been conducting research during the lasts year in the field of innovative modulations schemes and transceiver architectures trying to respond to the abovementined high data-rate in wireless environements considering the limitation imposed by existing electronic devices required to build the transceivers. Currently some solutions have been proposed from a theoretical perspective that need to the be brought forward in order to find optimal implementation with state-of-art technologies for integrated circuits design and fabricatino. This thesis subjet is inscreibed in the continuations of those previous works and will explore the practical implementation of circuits based on innovative modulation schmemes and architectures for hihg-speed, large-bandwidn, imperfection resilient mmW receivers.

Download the offer (.zip)

Tunable SOI-CMOS/GaN HPA for 5G infrastructure

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences

01-10-2020

SL-DRT-20-0839

ayssar.serhan@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

RF GaN technology has emerged as a strong candidate for high power 5G PA (HPA). The high power density, low output capacitance, and high breakdown voltage of GaN transistors make them attractive for the 5G small-cell market that requires several watts of output power at high frequencies (up to 40GHz). In this Ph.D. work, the student will investigate the heterogeneous SOI-CMOS/GaN Integration of a mmWave high-efficiency HPA. The output stage of the HPA will use Doherty architecture in order to achieve high-efficiency in the back-off region. It will be implemented on GaN to achieve the required power levels. To avoid the performances degradation of the Doherty stage over frequency, the input phase and driver level of the main and auxiliary transistors of the Doherty PA need to be carefully controlled. The driver stage of the Doherty stage will be implemented on SOI technology in order to enable tunability of the drive signals (phase and amplitude) using reconfigurable passives on SOI. This digitally assisted HPA will allow the optimization of both linearity and efficiency over wide frequency range of operation in a compact solution. This PhD thésis is proposed as an international PhD, diploma from University of Grneoble Alps, in collaboration with a European Partner. This PhD maybe a strong opportunity for the student for mutual collaboration, and a stay abroad.

Download the offer (.zip)

Advanced network management for controlling the real-time redeployment of a mobile network infrastructure under traffic performance constraints

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Laboratoire Systèmes Communiquants

01-09-2020

SL-DRT-20-0865

Michael.Boc@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

The digitization of industries introduces the need for providing high-speed wireless connectivity on industrial sites, which is extremely difficult due to the constraints imposed by these environments. To address them, this PhD thesis will investigate opportunities to increase real-time reconfiguration capabilities of the wireless infrastructure by means of an SDN-oriented management of the network. This network management will control the mobility of the infrastructure equipment as an additional degree of freedom in order to improve the performance of the data flows. This capability should provide two key benefits: 1) not having to rely on a lengthy and costly planning phase for network deployment, and 2) being able to implement new and more sophisticated network reconfiguration strategies to increase its overall performance level at any time. The mobility of the infrastructure could be provided by mobile robots that can be controlled through an SDN protocol and carrying some of the network equipment. In the case of a nuclear dismantling operation, for example, we could consider the wireless communication infrastructure as being composed of a fleet of mobile robots (terrestrial or aerial) whose mobility is managed by a network management system (SDN) in charge of ensuring the proper performance of the connectivity for dismantling robots remotely operated. The objective of the proposed thesis work is to define an advanced and centralized network management system for the control of the real-time redeployment of a mobile network infrastructure under performance constraints of data flows. This system should be able to 1) identify when a topological change becomes relevant considering the types of data flow performance problems and the limitations of existing network optimization solutions, 2) to define and pilot the redeployment of the network infrastructure in order to improve the performance of these data flows.

Download the offer (.zip)

Synthesis of wideband and compact antennas for the supergain and beam-forming

Département Systèmes (LETI)

Laboratoire Antennes, Propagation, Couplage Inductif

01-10-2020

SL-DRT-20-0878

antonio.clemente@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

Directive compact antennas offer new opportunities for wireless applications in terms of spectral efficiency, reduced environmental impact and use modes. However, the conventional techniques for enhancing the directivity often lead to a significant increase of the antenna size. Consequently, the integration of directional antennas in small wireless devices is limited. This difficulty is particularly critical for the frequency bands below 3 GHz if objects dimensions are limited to a few centimeters. Super directive/gain compact antennas with beam-steering capabilities and operating on a wideband or on multi-bands are an innovative and attractive solution for the development of new applications in the field of the connected objects. In fact, the possibility to electronically control the antenna radiation properties is an important characteristic for the development of the future generation and smart communication systems. CEA LETI has a very strong expertise in the domain of super directive antennas. The recent works realized demonstrated the potentials of the super directive compact parasitic antenna arrays. The PhD will take place at CEA LETI Grenoble in the antennas and propagation laboratory. The main objectives of this project are: i) the development of analytical and numerical tools for the synthesis, design and optimization of super directive compact arrays with beam-steering capabilities; ii) the study of new elementary sources for compact antenna arrays; iii) the realization and experimental characterization of a super directive compact array with beam-steering capabilities.

Download the offer (.zip)

Voir toutes nos offres