Marisa Lopez-Vallejo

Marisa Lopez-Vallejo
Universidad Politécnica de Madrid | UPM · Departmento de Ingeniería Electrónica

PhD. Telecommunication Engineering

About

169
Publications
16,397
Reads
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1,124
Citations
Introduction
Marisa Lopez-Vallejo currently works at the Departmento de Ingeniería Electrónica, Universidad Politécnica de Madrid. Marisa does research in Electronic Engineering and Engineering. One of their current project is 'VLSI Memristor/RRAM SPICE Compact Model'.
Additional affiliations
October 2002 - present
UPM
Position
  • Professor (Associate)
January 1996 - present
Universidad Politécnica de Madrid
Position
  • Professor (Associate)

Publications

Publications (169)
Article
Full-text available
Memristors offer the possibility of implementing multilevel cells in Resistive RAMs providing high-density non-volatile data storage solutions. However the writing and reading processes when these devices are integrated into a crossbar is a problem that has not yet been fully solved. Process and temperature variations must be carefully handled when...
Article
Power supply noise in current nanometer technologies represents a growing risk, specially because of the uncertainties it produces in the critical paths delays which can result in erroneous computations. Also, these very short variations can affect the functionality of analogue circuits like a comparator or an ADC. To tackle with these issues and t...
Article
Full-text available
There are emerging applications, like bridge structural health monitoring, continuous patient condition and outdoor aiding of the elderly and the disabled, where Internet of things (IoT) nodes are used with very limited accessibility and no connection to the main supply network. They may also be exposed to harsh environmental conditions. These are...
Article
Full-text available
In this work, we analyze in depth multiple characteristic data of a representative population of radenv-ADCs (analog-to-digital converters able to operate under radiation). Selected ADCs behave without latch-up below 50 MeV·cm2/mg and are able to bear doses of ionizing radiation above 50 krad(Si). An exhaustive search of ADCs with radiation charact...
Article
The high potential of memristors as multilevel resistance devices is undermined by their highly non-linear behaviour and a strong dependency on different sources of variability (process, voltage, temperature…). Temperature fluctuations are specially harmful because small thermal variations may significantly modify the operation point of the device....
Article
Dr. Xu Zhang is an assistant professor in the Department of Electrical and Computer Engineering at Carnegie Mellon University. He obtained his BS in physics from University of Science and Technology of China and his PhD in electrical engineering from Massachusetts Institute of Technology. He was an Enrico Fermi Fellow at Argonne National Laboratory...
Article
Full-text available
Artificial smokes focusing on macroscopic or fluid properties of smoke have been available for a long time. This paper presents a simple method to generate fully customizable smoke-like atmospheres at microscopic scale (i.e. considering their constituent particles as discrete elements) using a different approach. Synthetic, reproducible media can b...
Article
In this work a low power consumption reference voltage in commercial 40 nm technology is proposed. It adopts a new approach to produce a temperature invariant reference voltage for outdoor RFID applications. To do so, the positive temperature coefficient (TC) of the produced output voltage of a Dickson charge pump is used to cancel out the negative...
Article
Memristor crossbar arrays naturally accelerate neural networks applications by carrying out parallel multiply-add operations. Due to the abrupt SET operation characterizing most RRAM devices, on-chip training usually requires either from iterative write/read stages, large and variations-sensitive circuitry, or both, to achieve multilevel capabiliti...
Article
Full-text available
This paper focuses on the application of rapid prototyping techniques using additive manufacturing in combination with parametric design to create low-cost, yet accurate and reliable instruments. The methodology followed makes it possible to make instruments with a degree of customization until now available only to a narrow audience, helping democ...
Data
Custom combined arduino-controllable current driver for the high-power LEDs. The use of high power LEDs needs powerful current drivers controllable by an Arduino®UNO for higher customization. The circuits made use of an LM317, a well-known voltage regulator able to drive currents up to 1.5A. The LM317 fixes 1.25V between Vo and Vadj. This made it e...
Data
Source code. An archive with all the source files is attached. Please recall that they are available under GPLv2 or later. (ZIP)
Data
Block diagram of the algorithm. A blockwise, general view of the algorithm is provided showing input, processing and output stages along with their associated settings and parameters. (PDF)
Data
Expanded view of the instrument designed for the scattering measurements. The numbers therein correspond to the following parts: 1. Optical bench. 2. Base holder. 3. Intermediate holder. 4. Inner cylinder. 5. Linear holder for 50mm pipe. 6. Sensor (digital camera). 7. Pipe ending with camera holder and nebulizer inlet. 8. 50mm diameter EVA washer (...
Data
Photograph of the actual experimental setup. (TIFF)
Article
Every year, smarter and more complex attacks compromise electronic systems. Unauthorized access to the secure keys stored within nonvolatile memories is a concerning problem affecting secure applications. This paper presents an RRAM architecture secured against firmware and physical attacks. If a hack attempt occurs, and taking advantage of the thr...
Conference Paper
Full-text available
Resistive switching memories (RRAM) are an attractive alternative to non-volatile storage and non- conventional computing systems, but their behavior strongly depends on the cell features, driver circuit and working conditions. In particular, the circuit temperature and the writing voltage scheme become critical issues, determining resistive switch...
Article
Resistive switching memories (RRAM) are one of the most promising alternatives for non-volatile storage and non-conventional computing systems. However, their behavior, and therefore their reliability is limited by technology intrinsic constraints. Standard CMOS reliability analyses do not take into account RRAM related misbehaviors. Consequently,...
Article
Resistive switching memories [resistive RAM (RRAM)] are an attractive alternative to nonvolatile storage and nonconventional computing systems, but their behavior strongly depends on the cell features, driver circuit, and working conditions. In particular, the circuit temperature and writing voltage schemes become critical issues, determining resis...
Conference Paper
Nowadays the uncertainties produced by the com- bined effect of PVT Variations together with radiation dramati- cally compromises electronic systems behavior. Usually, radiation effects are studied from a digital point of view, analyzing upset error ratios and their consequences. In this work we redefine the analysis methodology of combined effects...
Conference Paper
Nanometer technologies are exposed to several sources of variability, among these, Power Supply Noise (PSN) has become a mayor challenge. This paper provides a broad perspective of the causes and effects of PSN along with the evolution of techniques that have been proposed to deal with it, which heavily rely on the information that can be gathered...
Conference Paper
The presence of noise in the power supply line in the form of ripples or spikes jeopardizes the behavior of electronic circuits. One solution to this problem is the use of power supply monitors that flag a signal whenever a hazardous situation is detected. In this paper we present a low area power supply monitor that detects under- and overshoots a...
Conference Paper
The effects caused by variability, temperature, radiation or aging may compromise the reliability of electronic circuits. Circuits designers must consider their combined effects early during the design cycle, even though it is a time and effort demanding task. In this work we present a methodology and simulation framework for the reliable design of...
Article
This brief presents a novel 4096-point radix-4 memory-based fast Fourier transform (FFT). The proposed architecture follows a conflict-free strategy that only requires a total memory of size $N$ and a few additional multiplexers. The control is also simple, as it is generated directly from the bits of a counter. Apart from the low complexity, the F...
Article
In this work we propose a physical memristor/resistive switching device SPICE compact model, that is able to accurately fit both unipolar/bipolar devices settling to its current-voltage relationship. The proposed model is capable of reproducing essential device characteristics such as multilevel storage, temperature dependence, cycle/event handling...
Article
Ring oscillators are one of the essential blocks in many electronic systems. Their versatility makes them suitable for many different applications including implementations for radiation environments. But under this scenario, it has been shown that the ring oscillator produces harmonic frequencies as a result of single event transient (SET) effects...
Article
Ring oscillators are used in many applications, but for all of them the system output is a clock signal with a 50% duty cycle. Our work sets the analytical basis for understanding and designing a ring oscillator whose outputs are clock signals with fully-configurable duty cycles different from 50%. We present two models in order to vary the output...
Conference Paper
Power supply noise in current nanometer technologies represents a growing risk, specially because of the uncertainties it produces in the critical paths delays which can result in erroneous computations. To tackle with these issues and to have a better power management, power supply monitors are necessary. Traditional approaches use an external ref...
Article
The performance of a Monte Carlo model for the simulation of electromagnetic wave propagation in particle-filled atmospheres has been conducted for different CUDA versions and design approaches. The proposed algorithm exhibits a high degree of parallelism, which allows favorable implementation in a GPU. Practical implementation aspects of the model...
Conference Paper
New CMOS technologies such as SOI or FinFET are expected to enhance SRAM radiation-induced soft error rates thanks to a reduction on the charge collected as the devices get smaller. In this work we analyze how the radiation hardening capabilities of SRAMs are affected when process variations are considered by simulating cells using a predictive Fin...
Article
Temporary loss of vision linked to certain high-risk professional activities increases stress and makes subjects prone to errors that may even cost lives. There is a clear demand for better vision and situation awareness tools for those users. In this paper, an extensive review of the basic theories behind remote sensing is conducted: mechanical wa...
Article
This paper describes a total ionization dose (TID) sensor that presents the following advantages: it is a digital sensor able to be integrated in CMOS circuits; it has a configurable sensitivity that allows radiation doses ranging from very low to high levels; its interface helps to integrate this design in a multidisciplinary sensor network; and i...
Article
The benefits of technology scaling have been accompanied by undesirable variations of a large number of parameters that need to be offset to ensure the proper operation of current electronic systems. Timing uncertainties are one of the most dangerous of these variation because they jeopardize the performance of the whole system. Critical-path monit...
Article
Spectral analysis plays an essential role in different applications. General-purpose spectrum analyzers are too expensive and are not appropriate for real-time applications. Therefore, a low-cost instrument for spectral analysis is needed. This paper describes a real-time field-programmable gate arrays implementation of a spectrum analyzer based on...
Article
This paper describes a statistical smoke model which can be of help to validate applications and technologies which imply propagation of electromagnetic waves through smoke-filled atmospheres. The approach followed is a time-resolved Monte Carlo simulation for use in quantitative as well as qualitative analysis of different types of smokes. The mod...
Article
An automatic modulation classifier (AMC) based on low-complexity signal features and a hierarchical decision tree is presented for pulsed radar applications. This AMC is implemented on a field-programmable gate array (FPGA) platform. The algorithm has been designed to minimize the computational burden to achieve real-time operation. The novelty of...
Article
Total Ionization Dose (TID) is traditionally measured by radiation sensitive FETs (RADFETs) that require a radiation hardened Analog-to-Digital Converter (ADC) stage. This work introduces a TID sensor based on a delay path whose propagation time is sensitive to the absorbed radiation. It presents the following advantages: it is a digital sensor abl...
Article
Since the memristor was first built in 2008 at HP Labs, no end of devices and models have been presented. Also, new applications appear frequently. However, the integration of the device at the circuit level is not straightforward, because available models are still immature and/or suppose high computational loads, making their simulation long and...
Article
Strained fin is one of the techniques used to improve the devices as their size keeps reducing in new nanoscale nodes. In this paper, we use a predictive technology of 14 nm where pMOS mobility is significantly improved when those devices are built on top of long, uncut fins, while nMOS devices present the opposite behavior due to the combination o...
Conference Paper
Nowadays integrated circuit reliability is challenged by both variability and working conditions. Environmental radi- ation has become a major issue when ensuring the circuit correct behavior. The required radiation and later analysis performed to the circuit boards is both fund and time expensive. The lack of tools which support pre-manufacturing...
Conference Paper
The usual way of modeling variability using threshold voltage shift and drain current amplification is becoming inaccurate as new sources of variability appear in sub-22nm devices. In this work we apply the four-injector approach for variability modeling to the simulation of SRAMs with predictive technology models from 20nm down to 7nm nodes. We sh...
Conference Paper
The estimation of pulsed radar signal parameters is a key task of an electronic intelligence (ELINT) equipment. All these signal parameters are compiled in a pulse description word (PDW). The post-processing of various PDWs from different receivers can provide valuable information about emitters. This paper presents a real-time FPGA implementation...
Article
Full-text available
SRAM-based FPGAs, like Xilinx Virtex series, are susceptible to ionizing radiation and require configuration memory scrubbing in order to be used in harsh radiation envi-ronments. The scrubbing is typically performed by a scrubber device external to the FPGA (via configuration ports). A design framework and methodology for such scrubbers is describ...
Article
Full-text available
This paper presents a novel self-timed multi-purpose sensor especially conceived for Field Programmable Gate Arrays (FPGAs). The aim of the sensor is to measure performance variations during the life-cycle of the device, such as process variability, critical path timing and temperature variations. The proposed topology, through the use of both comb...
Conference Paper
Full-text available
The implementation of a radar system is complex and expensive. It is then desirable to incorparate new capabilities through the lifetime of this kind of systems without modifying their underlying hardware. In this work we have taken advantage of the reconfigurability of FPGAs to incorporate pulse compression techniques in an already implemented sys...
Article
Full-text available
This paper presents a CMOS temperature sensor based on the thermal dependencies of the leakage currents targeting the 65 nm node. To compensate for the effect of process fluctuations, the proposed sensor realizes the ratio of two measures of the time it takes a capacitor to discharge through a transistor in the subthreshold regime. Furthermore, a n...
Conference Paper
We propose a way of modeling device variability in sub-threshold slope and DIBL at circuit-level using dependent voltage sources. The usual way of modeling variability using threshold voltage shift and drain current amplification is becoming inaccurate as new sources of variability appear in sub-22nm devices. Benchmark experiments on circuit level,...
Conference Paper
Power supply unpredictable fluctuations jeopardize the functioning of several types of current electronic systems. This work presents a power supply sensor based on a voltage divider followed by buffer-comparator cells employing just MOSFET transistors and providing a digital output. The divider outputs are designed to change more slowly than the t...
Conference Paper
The expected large variations of electrical characteristics of sub-22 nm devices represents a limitation on future electronic circuits. This is particularly relevant on RAM memories that have to ensure both read stability and write ability of all the cells. In this paper we present a 6T-SRAM designed with 14nm FinFETs that makes use of the negative...
Article
Full-text available
The high performance and capacity of current FPGAs makes them suitable as acceleration co-processors. This article studies the implementation, for such accelerators, of the floating-point power function xy as defined by the C99 and IEEE 754-2008 standards, generalized here to arbitrary exponent and mantissa sizes. Last-bit accuracy at the smallest...
Article
SRAM-based FPGAs are in-field reconfigurable an unlimited number of times. This characteristic, together with their high performance and high logic density, proves to be very convenient for a number of ground and space level applications. One drawback of this technology is that it is susceptible to ionizing radiation, and this sensitivity increases...
Article
This letter presents a temperature-sensing technique on the basis of the temperature dependency of MOSFET leakage currents. To mitigate the effects of process variation, the ratio of two different leakage current measurements is calculated. Simulations show that this ratio is robust to process spread. The resulting sensor is quite small-0.0016 mm2...
Conference Paper
Variabilities associated with CMOS evolution affect the yield and performance of current digital designs. FPGAs, which are widely used for fast prototyping and implementation of digital circuits, also suffer from these issues. Proactive approaches start to appear to achieve self-awareness and dynamic adaptation of these devices. To support these te...
Conference Paper
Full-text available
A common task in electronic design is the mod-eling and simulation of new devices. Sometimes the variety of models, the mathematical complexity of these or the existence of convergence problems during their simulation makes a difficult labor the development of software simulation tools. Moreover, the impact that PVT variations have in current nanom...
Conference Paper
In the recent years the missing fourth component, the memristor, was successfully synthesized. However, the mathematical complexity and variety of the models behind this component, in addition to the existence of convergence problems in the simulations, make the design of memristor-based applications long and difficult. In this work we present a me...
Conference Paper
Dynamic thermal management techniques require a collection of on-chip thermal sensors that imply a significant area and power overhead. Finding the optimum number of temperature monitors and their location on the chip surface to optimize accuracy is an NP-hard problem. In this work we improve the modeling of the problem by including area, power and...
Article
Full-text available
Current nanometer technologies suffer within-die parameter uncertainties, varying workload conditions, aging, and temperature effects that cause a serious reduction on yield and performance. In this scenario, monitoring, calibration, and dynamic adaptation become essential, demanding systems with a collection of multi purpose monitors and exposing...
Article
IntroductionFrom Where Does Heat Come in Nanometer Circuits?Harmful Effects Due to Temperature in VLSI ChipsTemperature Sensing for DTMThermal ModelingThermal Sensor Placement and AllocationTemperature Monitoring NetworksConclusions References
Article
Mersenne Twister (MT) uniform random number generators are key cores for hardware acceleration of Monte Carlo simulations. In this work, two different architectures are studied: besides the classical table-based architecture, a different architecture based on a circular buffer and especially targeting FPGAs is proposed. A 30% performance improvemen...
Conference Paper
This work proposes an encapsulation scheme aimed at simplifying the reuse process of hardware cores. This hardware encapsulation approach has been conceived with a twofold objective. First, we look for the improvement of the reuse interface associated with the hardware core description. This is carried out in a first encapsulation level by improvin...
Conference Paper
Full-text available
Linear regression is a technique widely used in digital signal processing. It consists on finding the linear function that better fits a given set of samples. This paper proposes different hardware architectures for the implementation of the linear regression method on FPGAs, specially targeting area restrictive systems. It saves area at the cost o...
Conference Paper
A cycle-accurate VHDL simulation model for the Xilinx Virtex-4 (and on) FPGA Configuration Layer is presented. This model allows for simulating configuration memory SEU injection and correction dynamics, as well as control logic SEFI recovery, with independence from Application Layer. Scrubber designs can be efficiently simulated, together with one...
Article
The high integration density of current nanometer technologies allows the implementation of complex floating-point applications in a single FPGA. In this work the intrinsic complexity of floating-point operators is addressed targeting configurable devices and making design decisions providing the most suitable performance-standard compliance trade-...
Conference Paper
Current nanometer technologies are subjected to several adverse effects that seriously impact the yield and performance of integrated circuits. Such is the case of within-die parameters uncertainties, varying workload conditions, aging, temperature, etc. Monitoring, calibration and dynamic adaptation have appeared as promising solutions to these is...
Article
Graphics Processing Units have become a booster for the microelectronics industry. However, due to intellectual property issues, there is a serious lack of information on implementation details of the hardware architecture that is behind GPUs. For instance, the way texture is handled and decompressed in a GPU to reduce bandwidth usage has never bee...