M. Kayal

École Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland

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Publications (169)87.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Classical substrate noise analysis considers the silicon resistivity of an integrated circuit only as doping dependent besides neglecting diffusion currents as well. In power circuits minority carriers are injected into the substrate and propagate by drift–diffusion. In this case the conductivity of the substrate is spatially modulated and this effect is particularly important in high injection regime. In this work a description of the coupling between majority and minority drift–diffusion currents is presented. A distributed model of the substrate is then proposed to take into account the conductivity modulation and its feedback on diffusion processes. The model is expressed in terms of equivalent circuits in order to be fully compatible with circuit simulators. The simulation results are then discussed for diodes and bipolar transistors and compared to the ones obtained from physical device simulations and measurements.
    Solid-State Electronics 03/2015; 105. DOI:10.1016/j.sse.2014.11.016 · 1.51 Impact Factor
  • Denis Sallin, Adil Koukab, Maher Kayal
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    ABSTRACT: In this Letter, a direct light-to-digital converter based on an MOS-PN photodetector driven by pulsed voltage is presented. The objective is to avoid any analog-to-digital or time-to-digital conversion and, thereby, to pave the way for a new generation of fully digital imaging sensors with reduced complexity, area, and power consumption. Moreover, the pulsed voltage operation allows for a significant reduction of the dark level. The concept is validated by a theoretical study and TCAD simulations. A first prototype fabricated in 0.18 μmCMOS technology is presented. The experimental results under various light conditions show that the pulsed voltage improves the light sensitivity by several orders of magnitude.
    Optics Letters 02/2015; 40(4):669-672. DOI:10.1364/OL.40.000669 · 3.18 Impact Factor
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    ABSTRACT: This paper presents an extended model for transient and ac circuit-level simulation of minority carriers propagation through the substrate of smart power integrated circuits (ICs). A p-n junction and a diffusion resistor with capacitive components are proposed to efficiently simulate transient parasitic coupled currents in high-power stages. From a general chip layout, an equivalent substrate network including capacitive effects (junction and diffusion capacitances) can be extracted and parasitic bipolar transistor can be simulated for the first time in transient operation by circuit simulators once the minority carriers continuity conditions are satisfied. This paper shows simulation results of the implemented models in good agreement with those obtained from technology computer-aided design. This implies that transient layout dependent mechanisms between high-voltage aggressor wells and low-voltage victims can be verified in early stages of IC design flow.
    IEEE Transactions on Electron Devices 01/2015; 62(4):1215-1222. DOI:10.1109/TED.2015.2397394 · 2.36 Impact Factor
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    ABSTRACT: Traditionally, photodiodes operate at static reverse bias, and incident light intensity is obtained from the relatively week photocurrent. In this paper, we introduce a different concept of photodiode function: the photodiode is used in a dynamic regime where it is switched from the reverse to forward state. Thus, the light intensity is defined not by the measured photocurrent but by the delay time of appearance of the strong forward current with the amplitude independent of the light intensity. Our experimental results as well as finite element modeling show that the dynamic mode of photodiode operation can potentially provide an improvement of the device performance.
    Applied Physics Letters 01/2015; 106. DOI:10.1063/1.4906488 · 3.52 Impact Factor
  • Denis Sallin, Adil Koukab, Maher Kayal
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    ABSTRACT: This paper presents a CMOS-compatible photodetector displaying direct light-to-time conversion and intrinsic charge integration with a very low dark current. This device is particularly adapted for applications requiring high-sensitivity such as bioluminescence detection. The effects of the physical structure, the process parameters, and the bias conditions on the device are discussed with the support of TCAD simulations and experimental measurements. The photodetector and its readout circuit are designed and implemented in standard 0.18 μm CMOS process. The experimental study shows promising tunability and sensitivity characteristics.
    IEEE Photonics Technology Letters 10/2014; 26(20). DOI:10.1109/LPT.2014.2346812 · 2.18 Impact Factor
  • Denis Sallin, Adil Koukab, Maher Kayal
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    ABSTRACT: This paper presents a fully Digital Pixel Sensor (DPS) front-end with a focus on its noise modelling and analysis. The design relies on a new type of photodetector displaying an intrinsic light-to-time conversion. Avoiding the pixel level analog processing improves significantly the overall performances of the image sensor. The photodetector as well as its front-end circuit are described. The noise performances and their variations with the physical and bias conditions are theoretically experimentally studied.
    IEEE International Conference on Electronics Circuits and Systems 2014; 09/2014
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    ABSTRACT: The current work focuses on presenting specific Hall cells with high performance, and their corresponding parameters. The design, integration, measurements and model development for their performance assessment are necessary stages considered in the generation of the Hall cells. Experimental results regarding the Hall cells absolute sensitivity, offset and offset temperature drift are provided for two particular structures exhibiting the best behavior in terms of maximum sensitivity and lowest offset. Three-dimensional physical simulations were performed for the structures and the Hall mobility was extracted. Representation of the inverse of the geometrical correction factor for the Greek-cross Hall cell is also provided.
    Microelectronics Journal 09/2014; 45(9). DOI:10.1016/j.mejo.2014.04.028 · 0.91 Impact Factor
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    ABSTRACT: Mass sensing has so far rather developed along the resolution axis, reaching atomic-scale detection, than into the direction of high-speed. This letter reports on a novel self-calibrating technique that makes high-speed inertial mass sensors capable of instant high-resolution detection and weighing. The sensing nanoelectromechanical resonator is embedded into a phase-locked loop and the sensor-inherent nonlinear phasefrequency relation is exploited for auto-calibration.
    IEEE Sensors Journal 08/2014; 14(8):1-1. DOI:10.1109/JSEN.2014.2322084 · 1.85 Impact Factor
  • C. Kauth, M. Pastre, M. Kayal
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    ABSTRACT: The state-of-the-art mass sensing so far has been rather developed along the resolution axis, reaching atomic-scale detection, than into the direction of high-speed. This paper reports a novel self-calibrating technique, making high-speed inertial mass sensors capable of instant high-resolution particle detection and weighing. The sensing nanoelectromechanical resonator is embedded into a phase-locked loop and the sensor-inherent nonlinear phase–frequency relation is exploited for auto-calibration. A tunable on-chip carbon nanotube based mass balance serves as a case study of small-size and low-cost environmental and healthcare applications. Tunability and a phase-locked loop topology make the system widely universal and invariant to nanotube characteristics. Operational for tube eigenfrequencies up to 385 MHz, the circuit integration in a 180 nm technology achieves instantaneous zeptogram resolution, while yoctogram precision is obtained within the tenth of a second. These figures of merit range at the physical limits of carbon nanotube resonators, in both mass- and time-resolution.
    Microelectronics Journal 08/2014; 45(12). DOI:10.1016/j.mejo.2014.07.004 · 0.92 Impact Factor
  • Source
    Denis Sallin, Adil Koukab, Maher Kayal
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    ABSTRACT: A new type of CMOS compatible photodetector, exhibiting intrinsic light-to-time conversion, is proposed. Its main objective is to start the time-to-digital conversion directly at its output, thereby avoiding the cumbersome analog processing. The operation starts with an internal charge integration, followed by a positive feedback, and a sharp switching-current. The device, consisting of a deeply depleted MOS structure controlling the conduction of a forward-based PN diode, is presented and its operation explained. TCAD simulations are used to show the effects of semiconductor parameters and bias conditions. The photodetector and its detection circuit are designed and fabricated in a 0.18µm CMOS process. Measurements of this new device under different biasing and illumination conditions show highly promising properties in terms of linearity, internal gain, and noise performances.
    Optics Express 06/2014; 22(12):14441-14449. DOI:10.1364/OE.22.014441 · 3.53 Impact Factor
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    ABSTRACT: Minority carriers diffusion currents are particularly important in parasitic substrate couplings of Smart Power ICs. In CMOS technologies the P-substrate potential is imposed by P+ contacts and N-wells by N+ highly doped implantations. The doping concentration discontinuity of these contact regions can have a big impact on parasitic diffusion currents of minority carriers. This work gives a description of these effects by device physical simulations of PN junctions under different injection levels of minority carriers. The perturbation of boundary conditions for electrons diffusion is also studied inside the substrate bulk in case a highly-doped substrate is used for high-voltage technologies.
    2014 10th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME); 06/2014
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    ABSTRACT: This paper presents an equivalent electrical circuit for one dimensional substrate minority carriers spice simulation. The electrical circuit parameters are extracted from substrate meshing applying the finite difference method. This model is derived from a linearization of drift-diffusion equations and not from the closed form solution. Further, the proposed circuit is solved with available SPICE simulators because of electrical analogies with physical quantities. Spice simulation results are compared with device simulator results. The accuracy of the model is dependent on the number of the discretization elements used. The minority carrier diffusion current is included automatically in the total substrate current computation.
    2014 MIXDES - 21st International Conference "Mixed Design of Integrated Circuits & Systems"; 06/2014
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    ABSTRACT: A new methodology for modeling minority carriers diffusion in Smart Power ICs substrate using standard circuit simulators has been proposed by EPFL. For this purpose, a parasitic substrate network consisting of lumped elements is extracted from the circuit layout following a given substrate meshing strategy. In this work Design of Experiments (DOE) techniques are used to run a limited number of simulations to evaluate the influence of the meshing on the accuracy of the EPFL Substrate Model when compared to finite element simulations. A two-dimensional case study on a parasitic lateral bipolar is then proposed with both spice-like and finite element simulation results for the minority carriers diffusion. A linear model is developed to estimate the most important geometrical domains influencing the accuracy of the studied model.
    2014 MIXDES - 21st International Conference "Mixed Design of Integrated Circuits & Systems"; 06/2014
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    ABSTRACT: This paper introduces the ICT/FP7 STREP project named AUTOMICS. AUTOMICS aims at modeling the substrate current induced by the minority carriers propagation in the substrate of smart power ICs where low and high voltage circuits are integrated on the same chip. Owing to switching of the high-voltage circuits, an induced minority coupling currents may detrimentally disturb the low voltage circuits. However, the substrate minority carrier current is not modeled in the existing models and the designers deal with this current based on their own experience. AUTOMICS attempts to solve this problem and provides facilities to ease the modeling of such parasitics. In AUTOMICS, a new enhanced diode and resistor model is used which accounts for the minority and majority carriers propagation in the semiconductor substrate. A generic CAD tool based on the enhanced diode and resistor models is intended to be developed in AUTOMICS. Using this tool, a circuit model for the whole substrate can be provided. The substrate circuit model in conjunction with the original circuit can be simulated for transient analysis. This will help in the investigation of the electrostatic discharge (ESD) phenomenon which is a compelling motivation of the project. The validation and verification of the designed models are provided by the AUTOMICS consortium. The significant impact of the project is to reduce the cost of the electrical vehicle, to enhance its reliability and to ensure its durability and safety.
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    ABSTRACT: We present the design considerations of an autonomous wireless sensor and discuss the fabrication and testing of the various components including the energy harvester, the active sensing devices and the power management and sensor interface circuits. A common materials platform, namely, nanowires, enables us to fabricate state-of-the-art components at reduced volume and show chemical sensing within the available energy budget. We demonstrate a photovoltaic mini-module made of silicon nanowire solar cells, each of 0.5 mm2 area, which delivers a power of 260 μW and an open circuit voltage of 2 V at one sun illumination. Using nanowire platforms two sensing applications are presented. Combining functionalised suspended Si nanowires with a novel microfluidic fluid delivery system, fully integrated microfluidic–sensor devices are examined as sensors for streptavidin and pH, whereas, using a microchip modified with Pd nanowires provides a power efficient and fast early hydrogen gas detection method. Finally, an ultra-low power, efficient solar energy harvesting and sensing microsystem augmented with a 6 mAh rechargeable battery allows for less than 20 μW power consumption and 425 h sensor operation even without energy harvesting.
    Microsystem Technologies 01/2014; · 0.95 Impact Factor
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    ABSTRACT: To foster the advent of miniaturized, self-controlled and highly sensitive nanoelectromechanical systems, a model for electromechanical resonator operation under the control of an adaptative phase locked loop is presented. The implications of limited observability, due to detectability thresholds and noise, on start-up and oscillation stability are analysed. Minimum system requirements, necessary for proper oscillation, are defined and a strategy for robust system design, under the constraint of finite real-world bandwidths, finally crystallizes.
    2013 IEEE 20th International Conference on Electronics, Circuits, and Systems (ICECS); 12/2013
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    ABSTRACT: We present a radiation-tolerant 120 dB dynamic-range interface circuit for ionization chambers and diamond detectors. The device consists of a multi-scale continuous-time incremental charge-to-digital converter paired with a temperature-compensated current reference. The circuit selects the sensitivity according to the input signal level and provides a 20-bit plus sign output code every 40μs. The proposed interface circuit achieves a measurement linearity error better than±5% in the 40 fC–42 nC range. The ASIC has been designed for radiation-tolerance in a 0.25μm 3M1P CMOS technology and tested for TID up to 100 kGy(Si), showing uninterrupted functionality. The conversion reference drifts of 3% at 100 kGy(Si) and its temperature coefficient is less than 600 ppm/°C.
    Microelectronics Journal 12/2013; 44(12):1302–1308. DOI:10.1016/j.mejo.2013.08.020 · 0.91 Impact Factor
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    ABSTRACT: This paper addresses the simulation of switched-capacitor circuits including capacitor nonlinearities at an intermediate modelling level, filling the gap between device level and behavioural level simulators. Starting with the resolution of the trivial case of integrator with ideal components, the impact of first- and higher-order capacitor nonlinearities is analyzed in detail and the related simulation approach is explained. As an application example, the expectable performance of a simulated incremental second-order ΣΔ converter is given.
    2013 IEEE 20th International Conference on Electronics, Circuits, and Systems (ICECS); 12/2013
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    ABSTRACT: This paper presents a fully integrated power management and sensing microsystem that harvests solar energy from a micro-power photovoltaic module for autonomous operation of a miniaturized hydrogen sensor. In order to measure H2 concentration, conductance change of a miniaturized palladium nanowire sensor is measured and converted to a 13-bit digital value using a fully integrated sensor interface circuit. As these nanowires have temperature cross-sensitivity, temperature is also measured using an integrated temperature sensor for further calibration of the gas sensor. Measurement results are transmitted to the base station, using an external wireless data transceiver. A fully integrated solar energy harvester stores the harvested energy in a rechargeable NiMH microbattery. As the harvested solar energy varies considerably in different lighting conditions, the power consumption and performance of the sensor is reconfigured according to the harvested solar energy, to guarantee autonomous operation of the sensor. For this purpose, the proposed energy-efficient power management circuit dynamically reconfigures the operating frequency of digital circuits and the bias currents of analog circuits. The fully integrated power management and sensor interface circuits have been implemented in a 0.18 μm CMOS process with a core area of 0.25 mm2. This circuit operates with a low supply voltage in the 0.9---1.5 V range. When operating at its highest performance, the power management circuit features a low power consumption of less than 300 nW and the whole sensor consumes 14.1 μA.
    Analog Integrated Circuits and Signal Processing 11/2013; 77(2):155-168. DOI:10.1007/s10470-013-0138-3 · 0.40 Impact Factor
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    ABSTRACT: This paper presents a fully analog demonstrator based on power system emulation for high-speed power system stability analysis. A benchmark using a fixed two-machine topology has been implemented. The characteristics of the emulated components (i.e., generators and transmission lines) are reprogrammable and short circuits can be emulated at different distances from the generator. This first realization is limited to transient stability analysis, as the main focus during design was put on computation speed. Indeed, the emulated phenomena are 10 000 times faster than real time. Moreover the authors aim to emphasize that such highly dedicated computation architectures are not only competitive in terms of speed, but also in terms of modularity.
    IEEE Transactions on Power Systems 11/2013; 28(4):4218-4227. DOI:10.1109/TPWRS.2013.2259185 · 3.53 Impact Factor

Publication Stats

591 Citations
87.82 Total Impact Points

Institutions

  • 2002–2014
    • École Polytechnique Fédérale de Lausanne
      • • Industrial Electronics Laboratory
      • • Institute of Electrical Engineering
      Lausanne, Vaud, Switzerland
  • 1990–2013
    • Eawag: Das Wasserforschungs-Institut des ETH-Bereichs
      Duebendorf, Zurich, Switzerland
  • 2008–2011
    • CERN
      Genève, Geneva, Switzerland
  • 2010
    • École Polytechnique
      Paliseau, Île-de-France, France
  • 2004
    • Politecnico di Bari
      Bari, Apulia, Italy