Integrated System for Adaptive Antenna Tuning and Synthesized Impedance in the Sub-6 GHz Band for Next-Generation RF Systems.
The growing adoption of sub-6 GHz RF systems for 5G, IoT, and wearable technologies has created a critical demand for compact, efficient, and adaptive solutions to enhance energy transfer, mitigate environmental detuning effects, and enable advanced sensing capabilities. This thesis proposes an innovative system-on-chip (SoC) that integrates an Antenna Tuning Unit (ATU) and a Synthesized Impedance Module (SIM) to address these challenges. By combining in-situ impedance measurement and dynamic re-adaptation, the system resolves a key limitation of miniature antennas—their extreme sensitivity to environmental perturbations, such as proximity to the human body or metal surfaces. Moreover, the integration of a Synthesized Impedance Module brings additional versatility by enabling the emulation of complex loads. This capability not only optimizes energy transfer but also allows for advanced functionality, such as material characterization and environmental sensing around the antenna.
A central focus of this research is the co-integration of a Vector Network Analyzer (VNA) with a broadband post-matching network (PMN) and a Synthesized Impedance Module. This combined architecture provides real-time impedance monitoring, dynamic tuning, and the generation of specific impedance profiles critical for characterizing the antenna's response under various scenarios. Guaranteed operation in the 100 MHz–6 GHz band is achieved while maintaining low power consumption through efficient duty cycling.
. Profile Sought : are you passionate about electronics and microelectronics and eager to contribute to a major technological breakthrough? We are looking for a motivated and curious candidate with the following qualifications:
. Education
Graduate of an engineering school or holder of a master’s degree in electronics or microelectronics.
Technical Skills
Strong knowledge of transistor technologies (CMOS, Bipolar, GaN…).
Expertise in analog/RF design.
Experience with design tools such as ADS and/or Cadence.
Programming
Basic skills in Python, MATLAB, or similar programming languages.
Additional Experience
Prior experience in integrated circuit design would be a valuable asset.
. Why Apply: you will have the opportunity to work on cutting-edge technologies in an innovative and collaborative research environment. You will be guided by renowned experts in the field to tackle exciting scientific and technical challenges.
Contacts: PhD. Ghita Yaakoubi Khbiza: ghita.yaakoubikhbiza@cea.fr, HDR. Serge Bories: serge.bories@cea.fr
Space-time Modulated Electromagnetic Metasurfaces for Multi-functional Energy-Efficient Wireless Systems
Next-generation (XG) wireless systems envision an unprecedented network densification and the efficient use of the near-millimeter-wave (mmW) spectrum. Disruptive concepts are required to minimize the number of antenna systems and their power consumption. Reconfigurable intelligent surfaces (RISs) can provide high-gain beam-forming using simple devices (e.g. p-i-n diodes) to control their scattering properties of their unit-cells. However, the efficiency of an RIS and the wireless functions it can simultaneously realize, are bound by its inherent linearity and reciprocity.
Space-time modulated metasurfaces (STMMs) have recently emerged as a beam-forming solution overcoming fundamental limits of linear time-invariant systems. Leveraging an additional time-variation of the unit-cell response, with respect to RISs, an STMM can tailor at the same time angular and frequency spectra of the radiated fields, without using multiple active circuits as in current systems.
Most models for the design of STMMs are oversimplified and consider 1-D modulations in quasi-static temporal regime. The impact of spatial discretization and phase quantization is overlooked. The few reported prototypes are often electrically small, with a coarse (half-a-wavelength) period. Most demonstrators operate in reflection, below 17 GHz and enable only a 1-bit phase resolution. Independent far-field beam-steering at several frequencies has been proved in a single scan plane.
This Ph.D. thesis aims at modelling, designing and demonstrating electrically large and multi-functional transmissive STMM antennas with enhanced phase resolution and beam-forming capabilities. Efficient numerical models will enable the computation of the fields scattered by a STMM in far- and near-field regions, for arbitrary spatial and time modulation periods. Holographic and compressive sensing techniques will be proposed to jointly optimize the metasurface phase profile and the time-modulation waveforms, enabling harmonic beam-shaping. A thorough study of the effect of phase resolution, STMM period and time-modulation frequency on the performance, power consumption and complexity of the control electronics will be provided.
A transmissive STMM prototype based on p-i-n diodes and enabling a 2-bit phase resolution will be realized for the first time, building on the group background on space-modulated electronically reconfigurable flat lens antennas. It will work in a frequency range suited to terrestrial and satellite networks (17-31 GHz). Multiple antenna functionalities will be experimentally characterized using the same prototype, such as: (i) simultaneous and non-reciprocal 2-D beam-forming at different harmonics of the time-modulating signals, in either far-field or near-field region; (ii) pattern shaping at the fundamental frequency, using optimized time-sequences to increase the effective phase resolution.
The fundamental and experimental contributions of this research will broaden the physical insight on time-modulated metasurfaces and increase the maturity of this technology for energy-efficient smart antennas with applications to wireless networks and integrated communication and sensing systems. An intense dissemination activity in high-impact scientific journals of electrical engineering and applied physics is expected, given the novelty of the topic and the growing interest it triggers in several communities.
Scalability of the Network Digital Twin in Complex Communication Networks
Communication networks are experiencing an exponential growth both in terms of deployment of network infrastructures (particularly observed in the gradual and sustained evolution towards 6G networks), but also in terms of machines, covering a wide range of devices ranging from Cloud servers to lightweight embedded IoT components (e.g. System on Chip: SoC), and including mobile terminals such as smartphones.
This ecosystem also encompasses a variety of software components ranging from applications (e.g. A/V streaming) to the protocols from different communication network layers. Furthermore, such an ecosystem is intrinsically dynamic because of the following features:
- Change in network topology: due, for example, to hardware/software failures, user mobility, operator network resource management policies, etc.
- Change in the usage/consumption ratio of network resources (bandwidth, memory, CPU, battery, etc.). This is due to user needs and operator network resource management policies, etc.
To ensure effective supervision or management, whether fine-grained or with an abstract view, of communication networks, various network management services/platforms, such as SNMP, CMIP, LWM2M, CoMI, SDN, have been proposed and documented in the networking literature and standard bodies. Furthermore, the adoption of such management platforms has seen broad acceptance and utilization within the network operators, service providers, and the industry, where the said management platforms often incorporate advanced features, including automated control loops (e.g. rule-based, expert-system-based, ML-based), further enhancing their capability to optimize the performance of the network management operations.
Despite the extensive exploration and exploitation of these network management platforms, they do not guarantee an effective (re)configuration without intrinsic risks/errors, which can cause serious outage to network applications and services. This is particularly true when the objective of the network (re)configuration is to ensure real-time optimization of the network, analysis/ tests in operational mode (what- if analysis), planning updates/modernizations/extensions of the communication network, etc. For such (re)configuration objectives, a new network management paradigm has to be designed.
In the recent years, the communication network research community started exploring the adoption of the digital twin concept for the networking context (Network Digital Twin: NDT). The objective behind this adoption is to help for the management of the communication network for various purposes, including those mentioned in the previous paragraph.
The NDT is a digital twin of the real/physical communication network (Physical Twin Network: PTN), making it possible to manipulate a digital copy of the real communication network, without risk. This allow in particular for visualizing/predicting the evolution (or the behavior, the state) of the real network, if this or that network configuration is to be applied. Beyond this aspect, the NDT and the PTN network exchange information via one or more communication interfaces with the aim of maintaining synchronized states between the NDT and the PTN.
Nonetheless, setting up a network digital twin (NDT) is not a simple task. Indeed, frequent and real-time PTN-NDT synchronization poses a scalability problem when dealing with complex networks, where each network information is likely to be reported at the NDT level (e.g. a very large number of network entities, very dynamic topologies, large volume of information per node/per network link).
Various scientific contributions have attempted to address the question of the network digital twin (NDT). The state-of-the-art contributions focus on establishing scenarios, requirements, and architecture for the NDT. Nevertheless, the literature does not tackle the scalability problem of the NDT.
The objective of this PhD thesis is to address the scalability problem of network digital twins by exploring new machine learning models for network information selection and prediction.
Sub-THz programmable electromagnetic surfaces based on phase change material switches
Spatiotemporal manipulation of the near- and far-electromagnetic (EM)-field distribution and its interaction with matter in the THz spectrum (0.1-0.6 THz) is of prime importance in the development of future communication, spectroscopy, imaging, holography, and sensing systems. Reconfigurable Intelligent (Meta)Surface (RIS) is a cutting-edge hybrid analogue/digital architecture capable of shaping and controlling the THz waves at the subwavelength scale. To democratize the RIS technology, it will be crucial to reduce its energy consumption by two orders of magnitude. However, the state-of-the-art does not address the integration, scalability, wideband and high-efficiency requirements.
Based on our recent research results, the main objective of this project will be to demonstrate novel silicon-based RIS architectures s at 140 GHz and 300 GHz. The enhancement of the THz RIS performance will derive from a careful choice of the silicon technology and, from novel wideband meta-atom designs (also called unit cell or element) with integrated switches based on PCM (phase change material). The possibility of dynamically controlling the amplitude of the transmission coefficients of the meta-atoms, besides their phase, will be also investigated. Near-field illumination will be introduced to obtain an ultra-low profile. To the best of our knowledge, this constitutes a new approach for the design of high-gain antennas in the sub-THz range.
RF Circuit Design for Zero Energy Communication
Our ambition for 6G communication is to drastically reduce the Energy in IoT. For that purpose we aim at developing an integrated circuit enabling zero Energy communication.
The objective of this PhD is to design this circuit in FD-SOI and operating in the 2.4 GHz. In this PhD, we propose to use a new design technique which is currently revolutionizing the radio-frequency design. We expect that many innovations can be carried out during this PhD by combining those two innovations.
The candidate will integrate a large design team and he will participate in collaborative project at european level. As a first step, he will analyze the system constraints to choose the best architecture and derive the specifications. Then, he will formalize mathematically the performances of the backscattering technique in order to setup a design methodology. Then he will be working full time on circuit design, sending to fabrication two circuits in 22 um technology. He will be also involve in the test of the circuit as well as in the preparation of a demonstrator of the backscattering techniques. We expect to publish several papers in high level conferences.
Distributed Passive Radar
Our objective is to detect and locate drones entering an urban area to be protected by observing the signals emitted by cellular stations. Studies have shown that it is possible to locate a drone if it is close to the listening system and the cellular station (i.e. the base station). When the situation is more complex (i.e. there is no direct path between the cellular station and the radar or in the presence of several transmitting cellular stations causing a high level of interference), a single listening system called passive radar cannot correctly detect and locate the drone. To overcome these difficult conditions, we wish to distribute or deploy in the area to be protected a set of low-complexity passive radars which optimally exploit the signals emitted by these cellular stations. A distribution and deployment strategy for passive radars must then be considered by taking into account the positions of the transmitting cellular stations. The possibility of exchanging information between passive radars must also be considered in order to better manage interference linked to cellular stations.
EM Signature Modeling in Multi-path Scenario for Object Recognition and Semantic Radio SLAM
Context:
The vision for future communication networks includes providing highly accurate positioning and localization in both indoor and outdoor environments, alongside communication services (JCAS). With the widespread adoption of radar technologies, the concept of Simultaneous Localization and Mapping (SLAM) has recently been adapted for radiofrequency applications. Initial proof-of-concept demonstrations have been conducted in indoor environments, producing 2D maps based on mmWave/THz monostatic backscattered signals. These measurements enable the development of complex state models that detail the precise location, size, and orientation of target objects, as well as their electromagnetic properties and material composition.
Beyond simply reproducing maps, incorporating object recognition and positioning within the environment adds a semantic layer to these applications. While semantic SLAM has been explored with video-based technologies, its application to radiofrequency is still an emerging area of research. This approach requires precise electromagnetic models of object signatures and their interactions with the surrounding environment. Recent studies have developed iterative physical optics and equivalent current-based models to simulate the free-space multistatic signature of nearby objects.
PhD Thesis:
The objective of this thesis is to study and model object backscattering in a multi-path scenario for precise imaging and object recognition (including material properties). The work will involve developing a mathematical model for the backscattering of sensed objects in the environment, applying it to 3D SLAM, and achieving object recognition/classification. The model should capture both near- and far-field effects while accounting for the impact of the antenna on the overall radio channel. The study will support the joint design of antenna systems and the associated processing techniques (e.g., filtering and imaging) required for the application.
The PhD student will be hosted in the Antenna and Propagation Laboratory at CEA LETI in Grenoble, France. The research will be conducted in partnership with the University of Bologna.
Application:
The position is open to outstanding students with a Master of Science degree, “école d’ingénieur” diploma, or equivalent. The student should have a specialization in telecommunications, microwaves, and/or signal processing. The application must include a CV, cover letter, and academic transcripts for the last two years of study.
Advanced RF circuit design in a system and technology co-optimization approach
This thesis addresses the two major challenges facing Europe today in terms of integrating the communication systems of the future. The aim is to design RF integrated circuits using 22nm FDSOI technology in the frequency bands dedicated to 6G, which will not only increase data rates but also reduce the carbon footprint of telecoms networks. At the same time, it is essential to consider the evolution of silicon technologies that could improve the energy efficiency and effectiveness of these circuits. This work will be carried out with an eye to the design methodology of radio frequency systems.
Within the framework of the thesis, the objective will be broken down into three phases. Firstly, simulation tools will be developed to predict the performance of Leti's future 10nm FDSOI technology. The second stage will involve identifying the most relevant architectures available in the literature for the application areas envisaged for the technology. A link with upstream telecoms projects will be systematically established to ensure that the candidate understands the systems' challenges.
Finally, in order to validate the concepts developed, the design of an LNA and a VCO as part of an ongoing project in the laboratory will be proposed.
The candidate will join a large team that works on new communication systems and addresses aspects of architectural study, modeling and design of integrated circuits. The candidate must have serious skills in the design of integrated circuits and radio frequency systems as well as good ability to work in a team.
Multipath-based Cooperative Simultaneous Localization & Mapping through Machine Learning
The goal of this PhD is to explore the potential of machine learning (ML) tools for simultaneous localization and mapping (SLAM) applications, while leveraging multipath radio signals between cooperative wireless devices. The idea is to identify characteristic features of the propagation channels observed over multiple radio links, so as to jointly determine the relative positions of the mobile radio devices, as well as those of scattering objects present in their vicinity. Such radio features typically rely on the arrival times of multipath echos of the transmitted signals. The envisaged approach is expected to benefit from multipath correlation as the radio devices are moving, as well as from spatial diversity and information redundancy through multi-device cooperation. The developed solution will be evaluated on both real measurements collected with integrated Ultra Wideband devices in a reference indoor environment, and synthetic data generated with a Ray-Tracing simulator. Possible applications of this research concern group navigation in complex and/or unknown environments (incl. fleets of drones or robots, firefighters…).
Magnetic DIsks as Transducer of Angular Momentum
The proposed topic is a collaborative project to exploit suspended magnetic disks as novel microwave transducers of orbital angular momentum. Our goal is to develop ultra-high fidelity opto-mechanical modulators operating at GHz frequencies by integrating magnetic materials into optical components. This innovative concept arises from recent progress in the study of angular momentum conservation laws by magnon modes in axi-symmetric cavities, leading to new opportunities to develop a more frugal, agile, and sustainable communications technology. Our proposed design has the potential to achieve coherent interconversion between the microwave frequency range in which wireless networks or quantum computers operate and optical network frequencies, which is the optimal frequency range for long-distance communications. In this regard, our proposal not only proposes new applications of magnonics to the field of optics not previously envisioned, but also builds a bridge between the spintronics and the electronic and quantum communities.
In this proposal, the elastic deformations are generated by the magnetization dynamics through the magneto-elastic tensor and its contactless coupling to a microwave circuit. We have shown that coherent coupling between magnons and phonons can be achieved by precisely tuning the magnetic resonance degenerate with a selected elastic mode via the application of an external magnetic field. We expect to achieve ultra-high fidelity conversion by focusing our study on micron-sized single crystal magnetic garnet structures integrated with GaAs photonic waveguides or cavities. In addition, we propose the fabrication of suspended cavities as a means to minimize further energy leakage (elastic or optical) through the substrate.
The first challenge is to produce hybrid materials that integrate high quality garnet films with semiconductors. We propose a radically new approach based on micron-thick magnetic garnet films grown by liquid phase epitaxy (LPE) on a gadolinium-gallium-garnet (GGG) substrate. The originality is to bond the flipped film to a semiconductor wafer and then remove most of the the GGG substrate by mechanical polishing. The resulting multi-layer is then processed using standard lithography techniques, taking advantage of the relative robustness of garnet materials to chemical, thermal or milling processes.
The second challenge is to go beyond the excitation of uniform modes and target modes with orbital angular momentum as encoders of arbitrarily large quanta of nJ? for mode multiplexed communication channels or multi-level quantum state registers. The project will take advantage of recent advances in spin-orbit coupling between azimuthal spin waves as well as elastic scattering of magnons on anisotropic magneto-crystalline tensors. In this project, we also want to go beyond uniformly magnetized state and exploit the ability to continuously morph the equilibrium magnetic texture in the azimuthal direction as a means of engineering the selection rules and thus coherently access otherwise hidden mode symmetries.