Ponencias (Instituto de Microelectrónica de Sevilla (IMSE-CNM))

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10971

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Mostrando 1 - 20 de 338

When Barkhausen's Criterion Does Not Suffice and you Must Rely on the Forgotten Art of Oscillator Design
(Institute of Electrical and Electronics Engineers (IEEE), 2024-08-01) Rodríguez Vázquez, Ángel Benito; Leñero Bardallo, Juan Antonio; Electrónica y Electromagnetismo
This paper recasts methods known for a long time to complement Barkhausen's criterion when designing oscillators. These methods rely on describing functions to linearize nonlinear systems and Routh-Hurwitz's criterion to study natural frequency movements around the imaginary axis. The paper set links to Lab exercises that employ Excel datasheet and SIMULINK models and are designed for students to gain insight into fundamental concepts about oscillator design.
Enhancing Dynamic Vision Sensors Performance with a Photovoltaic Receptor
(Institute of Electrical and Electronics Engineers (IEEE), 2025-01-28) Fernández Peramo, Pablo; Leñero Bardallo, Juan Antonio; Rodríguez Vázquez, Ángel Benito; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Ministerio de Asuntos Económicos y Transformación Digital. España
We introduce a Dynamic Vision Sensor (DVS) with a unique pixel architecture. Unlike conventional designs, the proposed architecture substitutes the photoreceptor front-end with a single diode operating in photovoltaic regime. Acting as a solar cell, this diode provides competitive sensitivity to transient illumination changes, especially in low-light settings, thanks to its self-biased condition and signal-noise ratio. This design offers compactness compared to logarithmic photorecep-tors. Additionally, it showcases highly competitive latency and noise performance.
Dynamic Slope Detection: A High-Compression Fidelity-Preserving Approach for ECG Signal Acquisition
(Institute of Electrical and Electronics Engineers (IEEE), 2024-09-16) Sáenz-Noval, Jorge J.; Leñero Bardallo, Juan Antonio; Gontard, Lionel C.; Tang, Wei; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Union (UE)
This paper introduces a novel Dynamic Slope De-tection (DSD) system for acquiring electrocardiogram (ECG) signals. DSD addresses the critical challenge of balancing data storage requirements with signal fidelity, particularly in resource-constrained environments like wearable devices. The system leverages the slope information of the ECG signal to guide efficient and adaptive data sampling. Validation using ten samples from the publicly available MIT-BIH Arrhythmia Database confirmed significant data reduction compared to traditional sampling. The proposed method achieves a compression ratio of up to 12.5× while maintaining RR interval estimation error below ±0.1 msec.
Design Lab-Based Learning of Analog Front-End Circuits: A Sigma-Delta Modulator Lab
(Institute of Electrical and Electronics Engineers (IEEE), 2024-08-01) Rodríguez Vázquez, Ángel Benito; Leñero Bardallo, Juan Antonio; Gómez Merchán, Rubén; Méndez Romero, Roberto José; Electrónica y Electromagnetismo
This paper details a Lab exercise that combines electrical and behavioral models to design ∑ΔMs. This Lab is suitable for students following an undergraduate course dealing with the design of analog-to-digital converters. Throughout the lab activities, students use different tools and modeling levels for the objects, similar to what they do in the profession. Data converter architectures employ high-level Simulink models to capture the nominal function and the thermal noise error. Active building blocks such as opamps and comparators employ electrical level and Spice simulations. Students are confronted with realistic active circuits and follow a guided methodology with a top-down complexity increase across the lab activities. Lab activities end by simulating mixed-signal circuits at the electrical level, which are complex and involve a large variety of building blocks (opamps, comparators, resistor string DACs, logic blocks, etc.). Tools employed are available at most universities, and the models are conceptually similar to those used in the profession.
Analysis and Simulation of Reset Leakage Currents and Quantization Error in a PFM Digital Pixel
(Institute of Electrical and Electronics Engineers (IEEE), 2024-11-11) Palomeque Mangut, Sergio; Fernández Peramo, Pablo; Leñero Bardallo, Juan Antonio; Rodríguez Vázquez, Ángel Benito; Electrónica y Electromagnetismo; European Defence Fund
This paper analyzes the design and performance optimization of the intensity-to-frequency converter in a Pulse-Frequency Modulated (PFM) Digital Pixel Sensor (DPS). We modeled the leakage currents induced by the self-reset feedback switch, which have a significant impact on its behavior. The work presents simulation results conducted in an advanced CMOS technology, illustrating the benefits of utilizing an NMOS reset to mitigate leakage, as opposed to a PMOS device. Additionally, the paper explores the consequences of quantization errors on sensor performance.
A Verilog-A/MS Compact Model for the Temperature Dependency of the Open-Circuit Voltage for Integrated Diodes
(Institute of Electrical and Electronics Engineers (IEEE), 2024-11-11) Fernández Peramo, Pablo; Leñero Bardallo, Juan Antonio; Palomeque Mangut, Sergio; Rodríguez Vázquez, Ángel Benito; Electrónica y Electromagnetismo; European Defence Fund
The open-circuit voltage is a crucial parameter that determines the harvesting capabilities of diodes operating in the photovoltaic regime. It is highly dependent on temperature and illumination which may limit the diode operation in application scenarios with large temperature and illumination variations as space instrumentation. The former dependence has not been modeled in a Hardware Description Language. This work presents a Verilog-A/MS based compact model to study and simulate the phenomenon. Validation of the model was conducted through TCAD simulations across a broad operational spectrum. The results affirm the model’s capability to analyze the impact of temperature fluctuations on solar cell performance accurately.
A Discrete Approach to Dynamic Vision with Single-Photon Detectors
(Institute of Electrical and Electronics Engineers (IEEE), 2024-07-02) Gómez Merchán, Rubén; Leñero Bardallo, Juan Antonio; Fernández Peramo, Pablo; Rodríguez Vázquez, Ángel Benito; Electrónica y Electromagnetismo
This paper presents a novel approach to implement discrete dynamic vision utilizing Single-Photon Avalanche Diode (SPAD) detectors. Departing from conventional continuous-time methodologies, our approach encodes photon arrival rates into frequency-based spikes, enabling asynchronous event-driven processing. The theoretical framework is validated through experimental results. Probability models for event detection and background noise are developed, demonstrating excellent agreement with theoretical predictions. The proposed probability models serve as a key tool for analyzing trade-offs between contrast sensitivity, speed, and background noise. This work not only advances the field of dynamic vision but also lays the groundwork for further innovations in SPAD-based imaging technologies.
Live Demonstration: A Photovoltaic Dynamic Vision Sensor
(Institute of Electrical and Electronics Engineers (IEEE), 2025-06-27) Fernández Peramo, Pablo; Leñero Bardallo, Juan Antonio; Rodríguez Vázquez, Ángel Benito; Electrónica y Electromagnetismo
Event-Based Pulse Frequency Modulated (PFM) Digital ROIC for Infrared Sensors
(Spie the International Society for Optical Engineering, 2025-10-28) Palomeque Mangut, Sergio; Fernández Peramo, Pablo; Martín-Arenas, Rafael; Rodríguez Vázquez, Ángel Benito; Leñero Bardallo, Juan Antonio; Electrónica y Electromagnetismo
An infrared detector is limited by the charge-handling capacity of the integration capacitor in the readout integrated circuit (ROIC). This is especially true for longer light wavelengths, due to higher background photon flux and dark current. For that reason, pulse frequency modulated (PFM) digital ROICs (DROICs) have drawn attention from the infrared community. These encode light intensity into a pulse train by recycling the capacitor, with pixels continuously integrating their photogenerated charge and generating a pulse when the accumulated charge reaches a threshold. Conventional PFM DROICs embed a digital counter inside each pixel to accumulate the number of pulses. However, these in-pixel circuits impose area penalties that limit scalability. This paper reviews the properties and design trade-offs of state-of-the-art PFM imagers and introduces a novel DROIC architecture with off-pixel counting. By relocating the counter logic and using an event-based interface, the proposed approach is suited for next-generation PFM DROICs with less than 10 μm pixel pitch.
Electromagnetic Side-Channel Attack on a SoC-FPGA Fingerprint Recognition System
(Institute of Electrical and Electronics Engineers (IEEE), 2025-12-11) Tejada Campos, Sergio; Arjona, Rosario; Román Hajderek, Roberto; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE)
Biometric-as-a-Service (BaaS) recognition systems have gained widespread adoption across several sectors due to their advantages in terms of cost-efficiency, scalability and performance. In these systems, the raw fingerprint images collected by sensors are transmitted to remote nodes through secure channels. The nodes often use SoC-FPGAs to accelerate processing with hardware. Also, they incorporate advanced security measures. However, they are not very concerned about possible side-channel attacks that can retrieve biometric data at operation level. To raise awareness of this problem, this paper presents an electromagnetic (EM) side-channel attack at a PYNQ Z1 board. It is performed while the SoC-FPGA is reading the fingerprint image from the DDR3 memory. Fuzzy-logic-based rules are extracted during a training phase to explain the correlation between the electromagnetic emanations measured and the pixels transmitted. With that rule base, the attacker needs only one EM trace, acquired in 69.10μs or less in our experiments, to reconstruct the fingerprint image, reaching pixel-wise accuracy of 99.05%.
A Preamplifier for the Front-End Readout System of Particles Tracking in Secondary Electron Detectors
(Institute of Electrical and Electronics Engineers (IEEE), 2012-08-20) Garzón Camacho, Alejandro; Fernández Martínez, Begoña; González Álvarez, Marcos Aurelio; Ceballos Cáceres, Joaquín Francisco; Rosa Utrera, José Manuel de la; Física Atómica, Molecular y Nuclear; Electrónica y Electromagnetismo; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
This paper presents the design and characterization of a preamplifier used in the electronic front-end of low-pressure gaseous secondary electron detectors. The circuit - implemented in a printed circuit board as a proof of concept - has been designed to cope with the specifications of the readout electronics used in spatial resolution measurements. Experimental results show a transimpedance gain of 80dB, an overall voltage gain of 18 dB, a peak signal-to-noise ratio of 36.5 dB and a shaping time frame of 140-170ns. These features improve the performance of previous reported approaches to the problem, and allow us to minimize the overlapping probability in secondary electron detections for radioactive ion beams tracking, achieving a counting rate higher than 106 particles per second.
A High-Level-of-Assurance EUDI Wallet with a Remote WSCD Supporting Biometrics and Passkeys
(Springer Nature, 2025-08-10) Franco, Claudia; Lancha, Carlos; Flores, Daniel; Arjona, Rosario; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE)
The European Digital Identity (EUDI) Wallet is a user-controlled digital environment that is being developed to be used by all citizens of the European Union. The Architecture and Reference Framework (ARF) of the EUDI Wallet is a set of specifications designed to ensure their interoperability and security. Among specifications, a Wallet Secure Cryptographic Device (WSCD) with a high Level of Assurance must be used. A high LoA is achieved through the multifactor authentication of the Wallet User and the use of secure hardware for implementing the needed cryptographic and biometric algorithms. Also, EUDI Wallets should include a functionality to generate and manage user-chosen pseudonyms, to authenticate Users when accessing online services. This paper describes a high LoA EUDI Wallet using a remote WSCD, which is the most inclusive, userfriendly and scalable type of WSCD. User authentication is done through something you know (a password), something you have (a smartphone), and who you are (with facial biometrics). As secure hardware for the remote WSCD, we use an Intel SGX enclave. The WSCD allows the generation and management of Passkeys, which are a kind of pseudonyms following the W3C WebAuthn specification. A demonstrator has been developed using a Samsung Galaxy A52 as User device with the Wallet Instance, and a laptop with an Intel® Core ™ i7-10750H at 2.60 GHz and 16 GB RAM with Ubuntu 20.04.6 LTS, Intel SGX1 and disabled hyper-threading to implement the remote WSCD. The experimental results show that the WSCD needs 128MB of RAM and takes 374.2 ms to be bound to a User, 375.2 ms to authenticate the User and create a new Passkey, and 373.8 ms to authenticate the User and sign with an already existing Passkey.
A Cloud-Based Multifactor Authentication Scheme Using Post-Quantum Cryptography and Trusted Execution Environments
(Springer Nature, 2025-08-10) Franco, Claudia; Arjona, Rosario; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE)
Since online transactions increase every day (banking, health services, etc.), authenticating the users in the cloud with a high level of assurance is a big concern. We propose a multifactor authentication scheme using post-quantum cryptography and trusted execution environments (TEEs). Three authentication factors are considered: what the user has (a device storing a secret), what the user knows (a password) and who the user is (with face biometrics). CRYSTALS-Kyber post-quantum public-key encryption is executed in an enclave of a TEE to encrypt a combination of the three factors mentioned. Instead of using the closed TEE solutions available in some personal devices, we propose an open solution that implements each personal enclave (linked to each personal device) in a biometric server. Instead of using a local authentication to unlock a personal device, we propose the use of another server (an authentication server), with another enclave, to authenticate each user in the cloud. The sensitive information concerning biometrics is always protected in a post-quantum manner, not only because it is obtained and encrypted inside an enclave on a biometric server but also because it is communicated, stored, and processed at the authentication server without being decrypted, thanks to the homomorphic property of Kyber. Our proposal is scalable for many users and secure against malicious adversaries. Experimental results using Intel SGX1 enclaves disabling hyper-threading and a facial recognition system show that the time to perform the crypto-biometric operations (excluding the feature extraction) is 1.55 ms and the accuracy considering only the biometric factor is 99.2% with an EER of 1.18%, which are competitive results compared to the state-of-the-art.
Multimodal IoT Device Authentication using Behavioral and Physical Unclonable Functions and Kyber Public Key Encryption
(Institute of Electrical and Electronics Engineers (IEEE), 2025-06-29) Román Hajderek, Roberto; Arjona, Rosario; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Union (UE)
Proper device identity management and authentication is a must for many Internet of Things (IoT) applications. Physical Unclonable Functions (PUFs) are a wellknown solution for identifying IoT devices. However, they can be attacked using both intrusive and non-intrusive physical attacks. In this work, we propose a multimodal device authentication scheme using Behavioral and Physical Unclonable Functions (BPUFs), which is a more secure option than PUFs. Adequate server-side security is achieved because BPUF responses are processed in the encrypted domain using homomorphic encryption. Furthermore, helper data attacks are avoided and the solution is quantum-safe. The proposal has been evaluated on an ESP32 microcontroller considering the security against false acceptance attacks and the security level of the Kyber public key encryption used. Fixing the first security to more than 192 bits for the behavioral and physical functions, the execution times of the cryptographic operations range from 41.30 to 205.70 ms, working at 160 MHz, with communication bandwidths from 3,840 to 15,680 bytes, and non-volatile memory occupation from 800 to 1,568 bytes.
An Educational Innovation Project Focused on the Implementation of Biometrics in Portable Devices
(Institute of Electrical and Electronics Engineers, 2024-08-01) Arjona, Rosario; López González, Paula; Arcenegui Almenara, Javier; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This work describes an educational project that explains how to extract biometric features from biometric samples acquired with microelectronic sensors suitable for portable devices (wearables and mobile phones) by satisfying low cost and reduced size. Specifically, fingerprints, ECG (electrocardiogram) and pulse signals, faces and veins are considered as biometric traits. Acquisition methods associated with this are fingerprint sensors, ECG electrodes and pulse sensors for wearables (in this work, a Raspberry Pi), and cameras for the acquisition of faces and veins in mobile phones. Then, it is explained how features are extracted and compared using biometric recognition algorithms selected to be implemented in portable devices: the feature QFingerMap16 (QFM16) for fingerprints, ECG and pulse waves, FaceNet embeddings for faces, and SIFT (Scale Invariant Feature Transform) for veins. Finally, it is explained how the features extracted are extensively evaluated by using public databases that contain samples acquired with sensors suitable for portable devices. Theoretical and experimental material for this research line and application field are distributed in four sessions lasting 4 hours and 30 minutes
Exploring Vein Biometrics on Ordinary Smartphones Using CNNs and Transfer Learning with Open and Closed Sets
(Institute of Electrical and Electronics Engineers, 2024-12-11) López González, Paula; Arjona, Rosario; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This paper explores the feasibility of using vein recognition for biometric authentication on ordinary smartphones. A new dataset, USE-V2, consisting of 6600 vein images from dorsal hands and wrists, was collected under three different ambient conditions. Instead of designing a Convolutional Neural Network (CNN) from scratch, we used transfer learning with a pre-trained FaceNet model for extracting vein features and evaluated its performance in both open-set and closed-set scenarios with USE-V2 dataset. The recognition performance is acceptable when an open-set scenario with selection of ambient condition is considered (average EER of 5.18% for dorsal hands and 5.88% for wrists), and quite competitive for a closed-set scenario (average EER of 0.6% for dorsal hands and 0.75% for wrists). This approach paves the way for an efficient multimodal system integrating facial and vein recognition on smartphones, sharing most of the CNN layers.
Post-quantum Secure Communication with IoT Devices Using Kyber and SRAM Behavioral and Physical Unclonable Functions (Extended Abstract)
(Springer nature, 2022-12-11) Román Hajderek, Roberto; Arjona, Rosario; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Ministerio de Ciencia e Innovación (MICIN). España
For a secure Internet-of-Things (IoT) ecosystem, not only the establishment of secure communication channels but also the authentication of devices is crucial. Authenticated key exchange protocols establish shared cryptographic keys between the parties and, in addition, authenticate their identities. Usually, the identities are based on a pair of private and public keys. Physical Unclonable Functions (PUFs) are widely used recently to bind physically the private key to a device. However, since PUFs are vulnerable to attacks, even non-invasive attacks without accessing the device, this paper proposes the use of Behavioral and Physical Unclonable Functions (BPUFs), which allow multimodal authentication and are more difficult to be virtually or physically cloned. In order to resist attacks from classic and quantum computers, this paper considers a Kyber key exchange protocol. Recently, Kyber has been selected by the Post-Quantum Cryptography standardization process of the National Institute of Standards and Technology (NIST) for key establishment protocols. In this work, we propose to strengthen a Kyber key exchange protocol with BPUFs extracted from SRAMs included in IoT devices. Experimental results prove the feasibility of the proposal in WiPy boards.
A Quantum-Resistant and Fast Secure Boot for IoT Devices Using Hash-Based Signatures and SRAM PUFs
(Springer Nature, 2022-06-12) Román Hajderek, Roberto; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Agencia Estatal de Investigación. España; Junta de Andalucía
Secure boot is a key security feature of trusted IoT devices. In this paper, a two-stage secure boot is proposed with two benefits: quantum-resistance and fast execution. In the verification of the first stage, an HMAC is used with a secret key reconstructed from an on-chip SRAM Physical Unclonable Function (PUF) and non-sensitive Helper Data (HD). Since the SRAM cells are classified conveniently in a registration phase, a simple repetition error correcting code is employed along with small-sized Helper Data. In the second-stage verification, the IoT device verifies the application firmware with a Winternitz One-Time Signature (WOTS+), which forms part of an eXtended Merkle Signature Scheme (XMSS). The full XMSS signature can be verified externally by the user of the device. Simple instances of tweakable hash functions proposed in SPHINCS+ are used for WOTS+ and XMSS schemes. The proposal is evaluated on the ESP32 microcontroller taking advantage of its available SHA accelerator. Working at 160 MHz, the first-stage verification takes only 6.04 ms. Excluding the message hashing, the second-stage verification takes from 5.12 to 25.83 ms depending on signature parameters. Compared with the XMSS RFC8391 reference implementation, from 304 to 608 bytes are not needed to be stored in the device. For a security of 128 bits, the proposal is from 17.25 to 39.77 times faster in cycles than the Elliptic Curve Digital Signature Algorithm (ECDSA) and saves 2992 bytes of flash memory.
Sealed storage for low-cost IoT Devices: An approach using SRAM PUFs and post-quantum cryptography
(Association for Computing Machinery, 2021-11-22) Román Hajderek, Roberto; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Agencia Estatal de Investigación. España; Junta de Andalucía
The number of Internet of Things (IoT) devices is increasing since they can solve many problems, such as those found in healthcare or power grid. Since they are susceptible to be attacked, solutions must be explored to make them more trustworthy and, thus, increment the confidence of their users. It is common that trusted devices use secret keys to achieve confidentiality of data stored in non-volatile memory, data in transit, and to authenticate themselves to other parties. However, these keys can be compromised if an attacker takes control of the platform by exploiting some vulnerability. In this work, we propose to seal the secret keys to the platform and to a specific state, mainly associated with the memory content and determined in a development stage. The secret keys are encrypted with a Sealing Secret Key that is not stored in the device, but obfuscated with an SRAM PUF, making it more secure. When a secret key has to be sealed or unsealed, functions called seal() and unseal() are employed. They have atomic execution and are stored in a ROM memory. Their goal is to measure the state of the platform and recuperate the sealing secret key only if the measurement matches a valid one signed by the application developer. As quantum computers are emerging and future IoT devices must be resistant to attacks performed by them, we choose Dilithium and Saturnin as cryptographic primitives. Benchmarking results taken in an ESP32 microcontroller show the suitability of the proposal for an IoT device.
Rule Simplification Method Based on Covering Indexes for Fuzzy Classifiers
(Institute of Electrical and Electronics Engineers Inc., 2021-08-05) Gersnoviez, Andrés; Baturone Castillo, María Iluminada; Electrónica y Electromagnetismo; Agencia Estatal de Investigación. España; Junta de Andalucía
A large number of rules increases the complexity of fuzzy classifiers and reduces the linguistic interpretability of the classification. A tabular rule simplification method that extends the Quine-McCluskey algorithm of Boolean design to fuzzy logic is analyzed in detail in this paper. The method obtains a few compound rules from many initial atomic rules. The influence of membership functions as well as t-norms and s-norms operands, which can be even null if many atomic rules are used, becomes apparent in the classification regions (decision boundaries) induced by the compound rules. Since the compound rules can be ordered according to the covering indexes that measure the number of atomic rules covered, more or less generic classification rules and rules with particular indexes can be further identified, which could ease subsequent classification or decision-making.

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