Photonic Spiking Neural Networks based on Q-switched laser integrated on Silicon
Neuromorphic networks for signal and information processing have acquired recently a renewed interest considering the more and more complex tasks that have to be solved automatically in current applications: speech recognition, dynamic image correlation, rapid decision processing integrating a plurality of information sources, behavior optimization, etc… Several types of neuromorphic networks do exist and, among them, the spiking type (SNN), that is, the one closest in behavior to the natural cortical neurons. SNN are the ones who seem to be able to offer a best energy efficiency and thus offer scalability. Several demonstrations have been made in this domain with electronic circuits and more recently with photonic circuits. For these, the dense integration potential of silicon photonics is a real advantage to create complex and highly connected circuits susceptible to lead to complete demonstrations. The PhD goal is to exploit a photonics spiking neuromorphic network architecture based on pulsed (Q-switched) lasers interconnected by a dense and reconfigurable optical network on chip mimicking the synaptic connections. A complete laser, neuron then circuit model is expected with, in the end, the practical demonstration of an application in mathematical data processing (to be defined).
Attacker model validation for laser-based attacks on integrated circuits
The security of embedded systems is nowadays a fundamental issue in many domains: IoT, Automotive, Aeronautics, among others. The physical attacks are a specific threat assuming a physical access to the target. In particular, fault injection attacks on the integrated circuits (IC) allows to disturb the system in order to retrieve secret material or to achieve a special goal such as by passing secure boot to execute malicious code. Due to their powerful capacities to defeat system security, developers must protect their system against such attack to be compliant with security standards such as Common Criteria and FIPS.
Within the context of continuous downscaling of silicon technologies, and with the transition to FD-SOI technologies, the vulnerability model of an IC must be drastically revised, from the transistor level up to the complex digital circuits one. In this PhD we propose to study the attacker model validation in the at the latter level. The objective is to contribute to the definition of a model of vulnerability after synthesis-of a RTL description of a circuit (for example a core processor) in a 22 nm FD-SOI technology. These models will contribute to define the attacker model injected as input in formal-based verification tools. The candidate will have to define a methodology to characterize with laser experiments the multilayer and heterogenous models in order to provide a quantitative analysis of their limit of validity. The methodology will be tested on ASIC realized by CEA for R&D projects allowing having a full control and knowledge of the architecture, of the design and synthesis parameters and the executed codes.
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
development of capacitive IIIV-Silicon modulators for emerging applications in silicon photonics
The proposed thesis work consists in developing phase modulators based on the integration of IIIV-Silicon hybrid capacitors in silicon waveguides, at a wavelength of 1.55µm to meet the emerging demands of photonics (optical computing on chip, LIDAR). Unlike telecom/datacom applications, which have enabled the emergence of integrated silicon photonics, these new application fields involve circuits that require a very large number of phase modulators. All-silicon modulators based on PN junctions, which have optical losses of several dB and centimeter sizes, are a bottleneck to the emergence of these applications.
IIIV-Si hybrid capacitors can allow, thanks to the electro-optical properties of IIIV materials, to reduce the size of silicon modulators by an order of magnitude and improve their energy efficiency (reduction of optical losses). First functional modulators have been designed, fabricated and tested. The first step will be to study in details their performance (losses, efficiency, speed, hysteresis) and to understand their limitations, using the available photonic simulation tools and electrical characterization methods (C(V), interface charge density, DLTS, etc.). In particular, this will involve better understanding the impact of the manufacturing process on the electro-optical properties. In a second step, the doctoral student will propose improvements to the designs and manufacturing processes (in collaboration with our microfabrication specialists), and will validate them experimentally using hybrid capacities and modulators integrating these capacities.
Increasing the electrothermal robustness of new SiC devices
Silicon Carbide (SiC) is a semiconductor with superior intrinsic properties than Silicon for high temperature and high power electronics applications. SiC devices are expected to be extensively used in the electrification transition and novel energy management applications. To fully exploit the SiC superior properties, the future semiconductor devices will be used under extreme biasing and temperature conditions. These devices must operate safely at higher current densities, higher dV/dt and higher junction temperatures than Si devices does.
The objective of this thesis is to study the SiC devices fabricated at LETI under these extreme operating conditions, and to optimize their design to fully use the theoretical potential of SiC. The thesis work will include several phases that will be strongly coupled:
- Advanced electro-thermal characterisation (50%), by proposing new approaches to testing components in a box or on a suitable support, using artificial intelligence (AI) tools for data extraction and processing. The work will include adapting standard measurement methodologies to the specific switching characteristics of SiC.
- An assessment (15%) of the design and technological parameters responsible for the operating limits of the components.
- A physico-chemical characterisation component (15%) to analyse failures under these extreme conditions.
- The inclusion of predictive models (20%) for the sensitivity of architectures to extreme conditions and faults, based on modelling.
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.
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.
Scalable thermodynamic computing architectures
Large-scale optimisation problems are increasingly prevalent in industries such as finance, materials development, logistics and artificial intelligence. These algorithms are typically realised on hardware solutions comprising clusters of CPUs and GPUs. However, at scale, this can quickly translate into latencies, energies and financial costs that are not sustainable. Thermodynamic computing is a new computing paradigm in which analogue components are coupled together in a physical network. It promises extremely efficient implementations of algorithms such as simulated annealing, stochastic gradient descent and Markov chain Monte Carlo using the intrinsic physics of the system. However, no clear vision of how a realistic programmable and scalable thermodynamic computer exists. It is this ambitious challenge that will be addressed in this PhD topic. Aspects ranging from the development computing macroblocks, their partitioning and interfacing to a digital system to the adaptation and compilation of algorithms to thermodynamic hardware may be considered. Particular emphasis will be put on understanding the trade-offs required to maximise the scalability and programmability of thermodynamic computers on large-scale optimisation benchmarks and their comparison to implementations on conventional digital hardware.
Study and evaluation of silicon technology capacities for applications in infrared bolometry
Microbolometers currently represent the dominant technology for the realization of uncooled infrared thermal detectors. These detectors are commonly used in the fields of thermography and surveillance. However, the microbolometer market is expected to grow explosively in the coming years, particularly with their integration into automobiles and the proliferation of connected devices. The CEA Leti LI2T, a recognized player in the field of infrared thermal detectors, has been transferring successive microbolometer technologies to the industrial partner Lynred for over 20 years. To remain competitive in this growing market for microbolometers, the laboratory is working on breakthrough microbolometers incorporating CMOS components as the sensitive element. In this context, the laboratory has initiated studies focusing on temperature-dependent silicon technology capabilities, with promising initial results not reported in the literature. The thesis topic fits into this context and aims to demonstrate the interest of these components for microbolometric applications. It will therefore cover the analytical modeling of these components and their associated physical effects, as well as the reading of such a component in a microbolometer imager approach. A reflection on technological integration will also be conducted. The student will benefit from several already realized technological lots to experimentally characterize the physical effects and familiarize themselves with the subject. To understand the encountered phenomena, the student will have access to the laboratory's entire test set-ups (semiconductor parameter tester, noise analyzer, optical bench, etc.) as well as the numerical analysis Tools (Matlab/Python, TCAD simulations, SPICE simulations, Comsol, etc.). By the end of the thesis, the student will be able to address the question of the interest of these components for microbolometric applications.