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S. Hamdioui

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Binary Neural Networks (BNNs) have obtained a strong foothold in the field of machine learning at the edge due to their minimal hardware requirements. However, their energy and performance efficiency remain hindered by frequent data transfer between memory and processors. Computation-in-memory (CIM) architectures address this problem by embedding processing units within the memory. Unfortunately, current implementations of CIM are susceptible to IP piracy attacks through side channels. This paper presents a novel secure periphery scheme for NN accelerators with sequential accumulation that conceals IP information by obscuring the power consumption of the counter responsible for the leakage. This is achieved by combining two innovative techniques: operand schedule randomization and an always-count Gray code counter. The results demonstrate that the proposed design effectively resists power side channel attacks (SCAs). Moreover, Signal-to-Noise Ratio (SNR) and Test Vector Leakage Assessment (TVLA) show safe leakage levels. Compared to the state-of-the-art, our countermeasure reduces area and power overheads by up to 12.7× and 13.3×, achieving only 37% area and 51.2% power overhead with the added protection logic. Notably, this enhanced security comes with zero latency overhead, maintaining the performance of the baseline design. ...

Layout-Aware Pre-Silicon Side-Channel Analysis

Power side-channel attacks pose a serious threat to cryptographic hardware implementations. To avoid deploying insecure implementations, it is essential to perform side-channel leakage assessments at the pre-silicon stage. Register Transfer Level (RTL)-level or gate-level power traces-generated, for example using SpyGlass, can be produced very efficiently but suffer from limited accuracy. In contrast, post-layout simulations provide a much higher accuracy but are prohibitively time-consuming. In this work, we propose a hybrid approach that extracts layout information, including timing and parasitic effects, and augments the gate-level netlist with this data. This approach enables fast pre-silicon power trace generation that accurately embeds post-layout parasitics. Our results show that power traces generated from gate-level and transistor-level simulations, both augmented with layout information, perform similarly in key-ranking anlysis and have a low Euclidean distance, while the gate-level simulations are 19 x-125 x faster to generate. ...
Conference paper (2026) - Pantazis Anagnostou, A.G.E. Van Zegbroeck, S. Hamdioui, Christoph Adelmann, Florin Ciubotaru, S.D. Cotofana
Spintronics, particularly Spin Waves (SWs), have recently demonstrated great potential for beyond-CMOS computing, owing to their unique properties and ultra-low power consumption. In this paper, we propose a novel concept for the realization of a Spintronics-based Threshold Logic Gate (SBTLG) that supports direct gate cascading. Specifically, the proposed device computes the weighted sum of $n$ SWs, with input values encoded in SW amplitude and weights emulated by Gilbert damping-induced amplitude attenuation. Subsequently, the threshold function is implemented via Domain Wall (DW) movement and pinning driven by the resulting weighted-sum SW towards a predefined location. DW presence/absence at the pinning site provides the gate logic output. We introduce the device concept, validate its operation by means of micromagnetic simulations, and perform a preliminary comparison against other state-of-the-art SW-based counterparts, showcasing 2% and up to 40% reduction in terms of area and energy consumption, respectively, at the expense of delay overhead. ...

Efficient Deep Learning Platforms for Next-Generation Embedded Edge-AI Systems

Conference paper (2026) - Rajendra Bishnoi, Mohammad Amin Yaldagard, Konstantinos Stavrakakis, Said Hamdioui, Kanishkan Vadivel, Pankaj Upadhyay, Nicolas Daniel Rodriguez, Teresa Van Dam, Sander Steeghs-Turchina, More Authors
The objective of our collaborative multi-partner project is to create an open-source Deep Learning framework called AIDGE for edge and embedded Artificial Intelligence (AI), built around an established European value chain. The framework is designed to support diverse application domains that function independently while serving a broad international community. It offers an integrated, full-stack workflow from Neural Network design and optimization to AI application development and hardware-level implementation with automated code generation for specific hardware targets. The platform aims to provide researchers and developers with a flexible environment to explore novel AI concepts, rapidly prototype solutions, and ensure strong alignment between academic research and industrial requirements. This paper summarizes the progress, outcomes, and milestones achieved up to the second year of this three-year project. ...
Journal article (2026) - Mohammad Amin Yaldagard, Ankit Bende, S.S. Diware, Vikas Rana, S. Hamdioui, R.K. Bishnoi
Resistive random-access memory (RRAM)-based computation-in-memory (CIM) architectures offer a promising solution to meet the stringent energy efficiency demands of executing artificial intelligence (AI) algorithms directly on edge devices. However, these architectures suffer from the read-disturb problem, which can lead to accumulated computational errors over time. To maintain the required level of computational accuracy, conventional approaches rely on a static reprogramming process after a predefined number of read cycles, necessitating large counters and resulting in inefficiencies. This paper presents experimental results using real RRAM devices to analyze the read-disturb effect and builds on these insights to propose a circuit-level detection methodology for real-time monitoring of conductance drifts. The proposed method initiates reprogramming only when the device drift exceeds a defined threshold and reprogramming is actually needed. Additionally, an analytical method is developed to determine the minimum conductance state ratio needed to meet reliable detection criteria. Based on this foundation, the proposed detection technique is further optimized for dynamic identification of read-disturb effects. Experiment-augmented SPICE simulation results, using a calibrated model implemented in TSMC 40 nm CMOS technology, validate the functionality and effectiveness of the proposed detection approach. These results demonstrate its potential to improve both the reliability and efficiency of RRAM-based CIM architectures that provide up to a 4x improvement in energy-efficiency compared to traditional periodic reprogramming methods. ...

A HW-Aware Fault Injection Framework for Digital Compute-In-Memory DNN Accelerators

Conference paper (2026) - P. Chaidos, A. Maras, Theofilos Spyrou, A.B. Gebregiorgis, S. Hamdioui, Dimitrios Soudris, Sotirios Xydis
Deep Neural Networks (DNNs) have been dominating the landscape of Artificial Intelligence (AI) applications in edge computing for several years, pushing developers to optimize architectural approaches and address power consumption concerns. Identifying memory transfers as the key contributor to the energy consumption of these workloads has led to the creation of architectures like Compute-In-Memory (CIM), bringing computation close to the storage, and thus eliminating the continuous data transfer overhead. However, reliability issues due to the environmental setting, device wear-out and operating conditions pose a significant challenge for such architectures as traditional approaches such as ECC are not adequate. To this end, we present CIM-FI, a hardware (HW) aware framework for injecting faults and analyzing the error resilience of modern DNNs on digital CIM (DCIM) accelerators. We present three diverse fault models related to DCIM soft errors, aging, and voltage scaling. The behavior of DCIM components is characterized using EDA tools and bit-level perturbations are injected into the weights and feature maps of DNNs at compile- and run-time. We test our model on three DNNs, including a Vision Transformer (ViT) and two Convolutional NNs (CNNs) and provide detailed analyses of the dependence between fault mechanism, target network and DCIM size. Our results show the interplay among these factors, the impact on accuracy and the necessity of HW-aware modeling in predicting unwanted drops in inference quality. ...
Although offering great potential for energy-efficient edge-AI, memristor-based CIM accelerators are severely hindered by IR drop induced errors. To tackle this, we propose a low-cost mitigation technique by first quantifying the impact of IR drop on the accuracy. Then, a mitigation strategy is developed to compensate for IR drop-induced inference accuracy reduction by combining an optimized mapping scheme with a fine-tuned calibration of the ADC. Results show the proposed solution can effectively mitigate IR drop with a negligible overhead. ...
Journal article (2026) - A. V. Zegbroeck, E. V. Meirvenne, P. Anagnostou, F. Ciubotaru, C. Adelmann, S. Hamdioui, S. Cotofana
Theoretically speaking, Majority logic, originally proposed in the ^{\prime }70s, enables more compact and efficient arithmetic implementations than the conventional Boolean counterpart. Nonetheless, CMOS technology based Majority logic realizations remain challenging, as standard transistor-based approaches are unable to directly exhibit majority behavior. However, recent exploration on beyond CMOS technologies created a resurgence of the interest in majority logic. In this work, we propose and analyze a novel approach towards the 3-input Majority gate (MAJ3) implementation by means of piezoelectric materials. By leveraging their intrinsic electromechanical properties, we convert the digital input signals into mechanical deformations, which are accumulated in a transfer layer. Subsequently, we transform the combined deformation back to the electric domain with a piezoelectronics element properly designed to perform majority functionality. We first present the underlying principles behind our proposal with a short introduction on majority logic, piezoelectronics, and the utilized simulation framework. Afterwards we introduce the proposed piezoelectric 3-input Majority gate (piezo-MAJ3) and strategies for optimizing its behavior and performance. We also detail the material parameters and structural design impact on device performance by utilizing both analytical discussion and physics-based simulations. Finally, we shortly highlight how our proposal can be directly integrated into CMOS circuits and compare the piezo-MAJ3 potential cost and performance with the ones of state of the art implementations. Our results indicate that when compared with its CMOS counterpart, the piezo-MAJ3 gate requires half the area, it is 7x faster, while reducing with 44% the energy consumption. ...

Side-Channel Weakness Evaluation and Enhanced Mitigation for DREAM-CIM

Computation-in-memory (CIM) accelerators offer energy and area efficiency gains but remain vulnerable to power side-channel leakage. This paper presents a comprehensive security analysis of a pipelined digital SRAM-based CIM accelerator named DREAM-CIM. We first identify leakage mechanisms through pre-silicon modeling and gate-level simulation, and then confirm their presence on a 22 nm post-silicon prototype. Moreover, to mitigate leakage, we introduce a Globally Synchronous and Locally Asynchronous (GSLA) countermeasure approach that desynchronizes immediate-pipeline-update registers and randomizes local activity while preserving functional correctness. Security is evaluated using post-silicon power traces under standard side-channel analyses, demonstrating effective leakage suppression. The countermeasure incurs ≈ 53% area and ≈ 74% energy overhead relative to the baseline design. Compared to masking-based countermeasures, GSLA achieves a reduction of ≈ 8.9 × and ≈ 9.2 × in area and energy overhead, respectively. ...

An Accurate and Scalable Simulator for Memristive Computing-in-Memory Accelerators

Computing-in-Memory (CIM) architectures using memristive crossbar arrays enable energy-efficient AI acceleration. Analog non-idealities, such as IR drop and nonlinearity, impose design constraints that existing simulators cannot capture and thus explore effectively. Current approaches sacrifice either modeling accuracy or simulation speed, preventing systematic design space exploration. In this paper we propose X-Sim, a crossbar simulator that resolves this trade-off through a modular architecture. Our approach decouples device physics from circuit analysis using a fixed-point scheme, avoiding expensive Jacobian computations while preserving device fidelity. X-Sim delivers SPICE-level accuracy (< 1% error) with up to 200× speedup over physics-based simulators. This enables quick and systematic design space exploration across thousands of configurations, guiding reliable system design. X-Sim will be released as open source. ...

Enhancing performance with temporal averaging and SIRENs

Journal article (2026) - Zacharia A. Rudge, Dominik Dold, Moritz Fieback, Dario Izzo, Said Hamdioui
Memristors are an emerging technology that enables artificial intelligence (AI) accelerators with high energy efficiency and radiation robustness — properties that are vital for the deployment of AI on-board spacecraft. However, space applications require reliable and precise computations, while memristive devices suffer from non-idealities, such as device variability, conductance drifts, and device faults. Thus, porting neural networks (NNs) to memristive devices often faces the challenge of severe performance degradation. In this work, we show in simulations that memristor-based NNs achieve competitive performance levels on on-board tasks, such as navigation & control and geodesy of asteroids. Through bit-slicing, temporal averaging of NN layers, and periodic activation functions, we improve initial results from around 0.07 to 0.01 and 0.3 to 0.007 for both tasks using RRAM devices, coming close to state-of-the-art levels (0.003−0.005 and 0.003, respectively). Our results demonstrate the potential of memristors for on-board space applications, and we are convinced that future technology and NN improvements will further close the performance gap to fully unlock the benefits of memristors. ...
This paper presents the first cryogenic characterization of Hot Carrier Degradation (HCD) in 5-V thick-oxide transistors fabricated in a 160-nm CMOS technology. HCD significantly worsens in nMOS devices at 4.2 K, leading to a more severe degradation, especially of threshold voltage and current in the linear regime. Contrary to expectations, pMOS devices exhibit a temporary performance improvement after stress, showing for the first time at 4.2 K a HCD-induced turn-around effect in threshold voltage and current. The threshold-voltage shift follows a power law with stress time, showing a much higher exponent at $4.2 K$ than at $300 K$ for nMOS, but not for pMOS devices. The threshold-voltage shift also follows a power law with stress voltage, strongly accelerated for nMOS at 4.2 K, but unchanged for pMOS. ...

Scalable, Ferroelectric-based Accelerators for Energy Efficient Edge AI (Ferro4EdgeAI)

Conference paper (2026) - Theofilos Spyrou, Yashvardhan Biyani, Konstantinos Stavrakakis, Rajendra Bishnoi, Said Hamdioui, Joel Minguet Lopez, Louise Dumas, Jean Coignus, Denys Ly, More Authors
The Computing-In-Memory (CIM) paradigm offers a promising solution to the memory-wall bottleneck that limits conventional Von Neumann architectures. By performing data processing at the same physical location where the data are stored, CIM-based architectures minimize costly data movement and drastically improve energy efficiency. When implemented with Ferroelectric Field Effect Transistors (FeFETs), additional advantages from the non-volatility, fast switching, and low operating voltage of FeFETs are added. However, the widespread adoption of FeFETs is limited by their poor endurance, which is overcome by a Back End of the Line (BEoL) integration of FeFET-2, where a ferroelectric capacitor (FeCAP) is wired to the gate of a CMOS transistor providing high endurance compatible with low-power edge applications. These properties enable dense, low-power, and high-speed matrix operations essential for AI workloads. As a result, FeFET-2-based CIM accelerators offer a promising solution for energy-efficient, high-performance AI at the edge. The Ferro4EdgeAI project aims to develop an ultra low-power, scalable edge accelerator for AI, targeting a significant gain in energy efficiency with respect to state-of-the-art AI hardware accelerators. To attain this, our project focuses on innovation all along the value chain from materials, physic concepts, device architecture, integration technologies, and accelerators in a holistic design space exploration approach. ...

Why Faulty Chips are Escaping the Fab and Crashing in the Field

Conference paper (2026) - Mottaqiallah Taouil, Shawn Blanton, Phil Nigh, Adit D. Singh, Said Hamdioui
The increasing complexity of semiconductor technologies is exposing limitations in traditional manufacturing test methodologies. Although fault-model-based testing has enabled efficient production screening for decades, growing evidence from advanced logic and memory technologies indicates that many realistic defect mechanisms are insufficiently represented by conventional fault abstractions, leading to test escapes and in-field failures. This paper examines three directions for improving outgoing product quality. First, we discuss the growing mismatch between fault models and actual silicon behavior and emphasize the need for silicon-informed assessment of defect coverage. Second, we investigate timing failures caused by process-variation-induced delay marginalities, which increasingly evade conventional scan-based delay testing. Finally, we present Device-Aware Test (DAT), a defect-centric methodology that derives fault models and test solutions directly from physical defect behavior. Examples from STT-MRAM, RRAM, and FeFET memories demonstrate how DAT enables the detection of realistic defect mechanisms beyond the reach of conventional approaches. Together, these directions support a transition toward defect-aware, data-driven testing for future semiconductor systems. ...
Conference paper (2026) - Soyed Tuhin Ahmed, Krishnendu Chakrabarty, Jin Fu Li, Mottaqiallah Taouil, Fouwad Jamil Mir, Said Hamdioui, Mehdi Tahoori, Martin Keim, Jongsin Yun
Compute-in-Memory (CiM) devices have several attributes that make them of interest especially for accelerating artificial intelligence workloads and, at the same time, reduce power consumption. Both are critical aspects of edge computing. This paper summarizes a 3-topic special session held at the European Test Symposium 2026 on the topic of CiMs: (a) concerning the reliability of CiMs, (b) the testing of CiMs, and finally (c) on the security of CiMs. ...
Efficient generation of high-quality Gaussian random numbers remains a key challenge for enabling differential privacy (DP) and security primitives on resource-constrained edge devices. Existing hardware-based solutions rely on lookup tables or complex transformations, making them ill-suited for tightly integrated computation-in-memory (CIM) architectures. This work proposes a Gaussian random number generator (GRNG) based on a digital 8T SRAM-CIM array that leverages intrinsic memory periphery to generate and transform entropy. The design exploits voltage underscaling and stochastic readpath failures to produce in-situ uniform randomness, which is then aggregated through a lightweight central limit theorem (CLT)-based datapath with digital recentering to synthesize N0, σ2) samples. By reusing existing periphery, the proposed approach eliminates the need for dedicated random number generation hardware. Experimental evaluation demonstrates that the generated distribution closely follows an ideal normal curve, achieving low tail error and strong goodness-of-fit across standard statistical tests. The design sustains ≈ 2 Gsamples s throughput at an energy of ≈ 11.2 fJ/ sample, with no additional area overhead beyond standard CIM periphery. ...
RRAM-based compute-in-memory (CIM) AI accelerators integrate memory cells with mixed-signal peripherals to enable energy-efficient, low-latency edge computing. These architectures require novel test techniques for unique electrical defects. Current system-level functional tests cannot guarantee defect-free circuits, while accurate circuit-level techniques remain non-scalable to Deep Neural Networks (DNNs). To bridge this gap, we present the first structural test methodology for CIM DNNs, unifying system-level analysis with circuit-level precision. We accurately model RRAM crossbar defects to formulate test patterns, and then propagate results across layers for comprehensive structural testing. Generated test patterns are optimized either for 96% defect coverage or test time reduction by a factor of three while covering all unique defects and maintaining over 73% defect strength coverage. ...

An overview from bio-inspiration to hardware architectures and learning mechanisms

Journal article (2026) - Anteneh Gebregiorgis, Amirreza Yousefzadeh, Sherif Eissa, Muhammad Ali Siddiqi, Charlotte Frenkel, Friedemann Zenke, Sander Bohte, Abdulqader Nael Mahmoud, Said Hamdioui, More authors...
The endeavor to emulate the extraordinary efficiency and adaptability inherent in the human brain via spike-based neuromorphic computing presents significant potential across a diverse array of applications. The attainment of this objective necessitates the translation of biological principles into artificial systems, a task that continues to pose a complex challenge requiring a profound comprehension of the mechanisms by which neural systems produce robust computational outcomes. This tutorial paper provides a comprehensive overview of the foundational concepts and emerging design trends in spike-based neuromorphic computing, covering advances from materials and circuits to hardware architectures and learning mechanisms. It begins with an examination of key aspects of brain biology and their influence on neuromorphic design, followed by a brief discussion of biologically plausible neuron and synapse models. The paper then defines the core principles and defining attributes of neuromorphic computing, highlighting the trade-offs and design choices underlying current implementations. Building on these foundations, it explores the critical properties of neuromorphic systems, surveys a variety of learning algorithms, and reviews hardware-level realizations of bioinspired neurons and synapses. Subsequent sections discuss state-of-the-art spiking neural network architectures, mapping and compilation strategies, and representative application domains. By providing this end-to-end perspective, the article aims to guide the development of future neuromorphic systems that more closely emulate brain efficiency, scalability, and resilience. ...
Mapping Binary Neural Networks (BNNs) on computation-in-memory (CIM) architectures enables a highly efficient approach for energy-constrained edge computing. In-memory processing significantly reduces critical performance bottlenecks in conventional architectures. Despite their efficiency, current optimized CIM implementations remain vulnerable to IP theft via side-channel analysis. This work investigates the side-channel leakage of a digital BNN-CIM accelerator that employs popcount-based accumulation. A range of circuit-level modifications in counter implementations are proposed and evaluated, exploring their impact on security metrics and design overhead. Results demonstrate that the Hamming weight (HW) and Hamming distance (HD) equalizing techniques combined with power equalization through duplication perform better than traditional dual-rail countermeasures. The findings provide practical guidance for designing secure and efficient peripheral components for popcount-based BNN accelerators. ...

Fast and Fault-Resilient PMP Reconfiguration for RISC-V

Conference paper (2026) - Christian Larmann, Abdullah Aljuffri, Adrian Marotzke, Alejandro Garza, Said Hamdioui, Mottaqiallah Taouil
This paper presents a Physical Memory Protection Snapshot Engine (PSE), a lightweight hardware extension for RISC-V that addresses both performance and security challenges of Physical Memory Protection (PMP) reconfiguration. By storing and restoring full PMP configurations in a single cycle, the PSE drastically reduces the overhead of context switches typically used in Trusted Execution Environments (TEEs) and secure real-time systems. At the same time, the redundant storage and two-dimensional parity protection provide an efficient and effective defense against fault injection attacks that target PMP registers. In 100k randomized trials, our experimental results demonstrate that the PSE can reliably detect and prevent FI-induced privilege escalations, while incurring only 11.7% area overhead. This makes it a practical solution for embedded devices where both efficiency and trustworthiness are essential. ...