M. Kayal

École Polytechnique Fédérale de Lausanne, Lausanne, Vaud, Switzerland

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Publications (148)58.5 Total impact

  • D. Sallin, A. Koukab, M. 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; · 2.04 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; · 0.91 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; · 0.91 Impact Factor
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    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. · 3.55 Impact Factor
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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; · 0.83 Impact Factor
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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. · 0.55 Impact Factor
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    ABSTRACT: In order to provide the information on their Hall voltage, sensitivity, and drift with temperature, a new simpler lumped circuit model for the evaluation of various Hall cells has been developed. In this sense, the finite element model proposed by the authors in this paper contains both geometrical parameters (dimensions of the cells) and physical parameters such as the mobility, conductivity, Hall factor, carrier concentration, and the temperature influence on them. Therefore, a scalable finite element model in Cadence, for behavior simulation in circuit environment of CMOS Hall effect devices, with different shapes and technologies assessing their performance, has been elaborated.
    Advances in Condensed Matter Physics 09/2013; 2013. · 1.18 Impact Factor
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    ABSTRACT: A micro-power energy harvesting system based on core(crystalline Si)-shell(amorphous Si) nanowire solar cells together with a nanowire-modified CMOS sensing platform have been developed to be used in a dust-sized autonomous chemical sensor node. The mote (SiNAPS) is augmented by low-power electronics for power management and sensor interfacing, on a chip area of 0.25mm2. Direct charging of the target battery (e.g., NiMH microbattery) is achieved with end-to-end efficiencies up to 90% at AM1.5 illumination and 80% under 100 times reduced intensity. This requires matching the voltages of the photovoltaic module and the battery circumventing maximum power point tracking. Single solar cells show efficiencies up to 10% under AM1.5 illumination and open circuit voltages, Voc, of 450-500mV. To match the battery’s voltage the miniaturised solar cells (~1mm2 area) are connected in series via wire bonding. The chemical sensor platform (mm2 area) is set up to detect hydrogen gas concentration in the low ppm range and over a broad temperature range using a low power sensing interface circuit. Using Telran TZ1053 radio to send one sample measurement of both temperature and H2 concentration every 15 seconds, the average and active power consumption for the SiNAPS mote are less than 350nW and 2.1 μW respectively. Low-power miniaturised chemical sensors of liquid analytes through microfluidic delivery to silicon nanowires are also presented. These components demonstrate the potential of further miniaturization and application of sensor nodes beyond the typical physical sensors, and are enabled by the nanowire materials platform.
    SPIE Microtechnologies; 05/2013
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    ABSTRACT: Five different Hall Effect sensors were modeled and their performance evaluated using a three dimensional simulator. The physical structure of the implemented sensors reproduces a certain technological fabrication process. Hall voltage, absolute, current-related, voltage-related and power-related sensitivities were obtained for each sensor. The effect of artificial offset was also investigated for cross-like structures. The simulation procedure guides the designer in choosing the Hall cell optimum shape, dimensions and device polarization conditions that would allow the highest performance.
    Sensors 01/2013; 13(2):2093-112. · 2.05 Impact Factor
  • C. Kauth, M. Pastre, M. Kayal
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    ABSTRACT: To foster the development of highly sensitive carbon nanotube nanoelectromechanical sensor systems, a computationally light analytical and semi-empirical model for the latter's dynamics, electromechanical and piezoresistive properties is presented. This model is the breeding ground for the subsequent design and implementation of a phase locked loop and feedback circuitry, which form an adaptive closed-loop oscillator for actuation, detection and sustainment of the sensor's motion.
    Mixed Design of Integrated Circuits and Systems (MIXDES), 2013 Proceedings of the 20th International Conference; 01/2013
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    ABSTRACT: The emerging field of power system emulation for real time smart grid management is very demanding in terms of speed and accuracy. This paper provides detailed information about the electronics calibration process of a high-speed power network emulator dedicated to the transient stability analysis of power systems. This emulator uses mixed-signal hardware to model the dynamic behavior of a power network. Special design allows the self-calibration of the analog electronics through successive measurements and correction steps. The calibration operation guarantees high resolution of the transient stability analysis results, so that they can be reliably used for operational planning and control on real power networks.
    Mixed Design of Integrated Circuits and Systems (MIXDES), 2013 Proceedings of the 20th International Conference; 01/2013
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    ABSTRACT: In real time scenario, transmission (of power) in power systems may not be always ideal i.e. they may be interrupted. As a result, the synchronization among the power generating modules may be lost. Loss of synchronization has a direct effect on the stability of power generators. Generally time domain simulation (TDS) is used to examine the stability but TDS is a time consuming process, hence we are required to explore other approaches. Accurate real-time security assessment is necessary to facilitate operations close to the stability limits. Hence for this purpose a distributed time efficient approach has been adopted to predict future values of system parameters and use the same to predict future stability of power generating modules by partially using artificial neural network and fuzzy interference system based on European Network of Transmission System Operators for Electricity (ENTSO-E) defined criteria.
    Innovative Smart Grid Technologies - Asia (ISGT Asia), 2013 IEEE; 01/2013
  • C. Kauth, M. Pastre, M. Kayal
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    ABSTRACT: A tunable and self-regulating on-chip carbon nano-tube based mass balance is presented for small-size and low-cost environmental and healthcare applications. Tube stretching and a phase-locked loop topology make the system widely universal and invariant to nanotube characteristics. Operational for tube eigenfrequencies up to 385MHz, the circuit integration in a 180nm 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.
    Advances in Sensors and Interfaces (IWASI), 2013 5th IEEE International Workshop on; 01/2013
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    ABSTRACT: This paper presents a fully integrated solar energy harvester for ultra-low power autonomous microsystems. This area- and power-efficient circuit harvests solar energy from a micro-power photovoltaic module to charge a rechargeable NiMH microbattery. As the harvested solar energy varies considerably in different lighting condition, the proposed circuit scales the power consumption and performance of the target microsystem, according to the harvested solar energy. Battery voltage is measured when battery is discharged by a high discharge current, to estimate harvested solar energy. Operating frequency and supply voltage of digital circuits and bias currents of analog circuits are reconfigured dynamically, based on measured battery voltage to optimize power-performance of the microsystem. This circuit occupies a core area of only 0.2mm2 in a 0.18μm CMOS process and features a low power consumption of 390nW operating at its highest clock frequency.
    Circuits and Systems (ISCAS), 2013 IEEE International Symposium on; 01/2013
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    ABSTRACT: This paper presents an innovative 3D hardware architecture for power system dynamic and transient stability. Based on an intrinsic parallel architecture by means of mixed-signal circuits (analog and digital) it overcomes the speed of numerical simulators for given models. This approach does not competing the accuracy and model complexity of the high performance numerical simulators. It intends to complement them with the advantage of speed, low-cost, portability and autonomous functions. The presented architecture provides an ultra-high speed platform by means of emulation principle. The proof of concept is an array of 4×24 nodes reconfigurable platform. Hardware details and comparisons with a reference digital simulator are given.
    PowerTech (POWERTECH), 2013 IEEE Grenoble; 01/2013
  • C. Kauth, M. Pastre, M. Kayal
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    ABSTRACT: A closed-loop oscillator topology is proposed for dynamic sensor operation of nanoelectromechanical systems, benefiting from the structure's quality factor. Automatic adaptation to diverse sensors' properties is achieved via a self-regulating phase-locked loop, making the topology widely usable. A low-noise programmable harmonic LC oscillator forms the cornerstone of its design. Integrated in a 180 nm technology, a tuning range from 600 MHz to 770 MHz is obtained.
    New Circuits and Systems Conference (NEWCAS), 2013 IEEE 11th International; 01/2013
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    ABSTRACT: This paper describes a mixed-platform framework dedicated to Dynamic Stability Assessment of power systems. DSA refers to tools capable of characterizing the dynamic stability of the system. Time domain simulation is critical for DSA analysis and is done by algorithms known as TD engines. In this work, operations are shared between a software platform and a hardware one. TD simulation is handled by a dedicated mixed-signal electronics implementation. Data flow control, user interfacing, configuration, result post-processing and other auxiliary operations are realized in software. This architecture combines the flexibility of the software with the high-performance of dedicated hardware. Results of a multi-contingency analysis and a critical clearing time determination analysis for sample test cases are presented. It is demonstrated that an increase in speed of almost three orders of magnitude can be achieved, compared to single-platform solutions.
    Power and Energy Society General Meeting (PES), 2013 IEEE; 01/2013
  • Conference Paper: A DC power flow extension
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    ABSTRACT: In this work an extension of the well-known DC power flow method is presented. A normal DC power flow of the system is executed to determine voltage angles and a novel derivation of voltage amplitudes is devised. The latter is rigorously formulated and eight alternative ways to tackle it are proposed. Comparative studies between the proposed versions of the algorithm verify its effectiveness in producing an accurate estimate of the voltage profile, on average in the order of 10-3 pu close to the exact solution. The proposed algorithm features very favorable computational requirements of approximately a fifth of the time required for an exact solution. Its computational efficiency renders it a solid candidate for hard real-time applications required in the emerging smart grid.
    Innovative Smart Grid Technologies Europe (ISGT EUROPE), 2013 4th IEEE/PES; 01/2013