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2017

Jamel NEBHEN; Stephane MEILLERE; Mohamed MASMOUDI

A high linear and temperature compensation ring VCO for random number generator , ASP Journal of Low Power Electronics, JOLPE, Vol. 13, N° 4, December 2017. , 2017-12-01
[Abstract]
Abstract
In this paper, we propose a very simple ring VCO structure for use in a variety of applications ranging from the data encryption and mathematical simulation to the built-in-self test (BIST) of RF receivers. The proposed ring VCO has two advantages; its linearity is greatly improved compared to published VCO and the circuit is temperature compensated through a bandgap reference. The chip is fabricated in AMS 0.35 ?m CMOS technology with 2.5 V power supply. The total area is 0.02 mm2. A series of measurement results confirm the validity of the proposed circuit. Operating at 2.5 V, the output frequency is within 300 ± 2 MHz over the temperature range of -20 °C to 80 °C with power consumption of 400 ?W.

2015

J. Nebhen, S. Meillère, M. Masmoudi, J. L. Seguin, K. Aguir

Design of new low-noise and low-power CMOS differential pair , Electronics Letters 3rd September 2015 Vol. 51 No. 18 pp. 1433–1435 , 2015-07-23
[Abstract]
Abstract
This paper presents a novel structure of a CMOS differential pair, suitable for low supply voltages and low power consumption as well as a much higher gain than that of a conventional differential pair. This structure is based on the new technique of composite transistors. This paper shows the need for the design of integrated circuits at low voltage, low power consumption and how this constraint is reflected in the design of digital integrated circuits and design of analog integrated circuits.

B. Mezghani, F. Tounsi and M. Masmoudi

Development of an accurate heat conduction model for micromachined convective accelerometers , MICROSYSTEM TECHNOLOGIES, SPRINGER, http://dx.doi.org/10.1007/s00542-014-2079-x, 21 (2), 345-353. , 2015-01-05
[Abstract]
Abstract
This paper presents detailed development of a heat conduction model adapted for micromachined convective accelerometers. Fitting expressions obtained from FEM data are used in derived spherical model expressions to come up with an accurate analytical model of heat conduction main parameters: common mode temperature and heat transfer coefficient. Two variables have been used in FEM analysis: applied heater temperature and micromachined cavity depth. The latter parameter has a large impact on the overall conductive behavior of thermal accelerometers since it fixes the volume where produced heat bubble can expand. In addition, this depth is one of the two main reasons behind the produced isotherms deformation. Isotherm bending is also due to the high aspect ratio in heater width and height imposed by the technology. Since the produced hot bubble form is closely related to sensor design and heater temperature, then spheres deformation modeling has been used to derive conduction model equations. Two distinct equivalent radius modeling are studied and are used to express conduction behavior in analytical expressions. For comparison, Hardee’s conduction solution is given and it has found that our solution gives a more accurate reading of common mode temperature. Therefore, Hardee’s solution has to be revised if it is to be used for convective accelerometers. It is also shown that derived expressions are still valid for various sensor designs and that conductive behavior of thermal accelerometers can be predicted in an early stage and for all possible design geometries and biasing temperatures.

2013

B. Mezghani, F. Tounsi, A.A. Rekik, F. Mailly, M. Masmoudi and P. Nouet

Sensitivity and power modeling of CMOS MEMS single axis convective accelerometers , Elsevier Microelectronics Journal, Vol. 44, Issue 12, Dec 2013, pp 1092–1098. , 2013-12-12
[Abstract]
Abstract
In this paper,we present 3D finite element modeling and simulation of a CMOS/MEMS single axis convective accelerometer. We describe the sensor architecture and present a sensor geometry model to be used in 3D FEM simulations. Differences between 3D and previously published 2D simulation sare discussed. This work investigates 3D effects which give the opportunity to better predict not only sensor sensitivity but also power dissipation.Experimental sensitivity values and 3D FEM ones are compared for two different sensor geometries and two different heater temperatures.For a prototype having a heater- cavity border distance of 340 mm and a heater length of 230 mm, maximum sensitivity point is obtained for detectors localize data distance of 125 mm from heater center.This distance should be moved to 90 mm if a 50 mm heater length issued. So, detectors should be placed closer to the heater than the usually used mid-distance. Moreover, optimal detectors location shifts closer to the heater as heater length shrinks. We also show that if heater length is reduced by 80% (from 230 to 50 mm), then both electrical power and sensitivity decrease by 63% and 55%,respectively. So, best efficiency is obtained for shorter heaters. In addition, detector's length decrease is found to have a significant effect on sensitivity, with an increase of 58% and 87% using heater lengths of 230 mm and 50 mm, respectively. Here, detector's length decreased from the total side bridge length to a fraction of this length equals to 2.5%.Optimal length is obtained when detectors are implemented on the same side bridge fraction as that used to implement the heater on the central bridge.

J. Nebhen, E. Savary, W. Rahajandraibe, C. Dufaza, S. Meillère, E. Kussener, H. Barthélemy

Low-Noise CMOS Analog-to-Digital Interface for MEMS Resistive Microphone , IEEE International Conference on Electronics, Circuits, and Systems (ICECS), Abu Dhabi, UAE , 2013-12-08
[Abstract]
Abstract
This paper presents the design and electrical implementation of a CMOS integrated analog to digital interface dedicated to the hybrid integration of a MEMS resistive microphone with readout interface. Audio sensing is achieved with an innovative low-cost technology that implements piezoresistive detection in MEMS devices with single crystal silicon nanowires. The circuit is composed of a low-noise instrumentation preamplifier and a fourth order, single bit continuous-time sigma-delta modulator (CT-??M) systems. The circuit has been designed in a 0.28 ?m CMOS process with a 2.5 V supply voltage and occupies an area of 1mm2. For the Postlayout Simulation, the design of both circuits achieves a noise floor of 8 nV/?Hz within the frequency range from 10 Hz to 10 kHz. The complete interface circuit features a current consumption of 4mA.

B. Mezghani, F. Tounsi and M. Masmoudi

Static behavior analytical and numerical analysis of micromachined thermal accelerometers , TRANSACTIONS ON SYSTEMS, SIGNALS & DEVICES (TSSD), ISSUES ON SENSORS, CIRCUITS & INSTRUMENTATION SYSTEMS, SHAKER-VERLAG GMBH, 9 (4), 1-21. , 2013-09-16
[Abstract]
Abstract
This paper presents static behavior analytical study of micromachined convective accelerometers. This includes both heat conduction and convection behavior study and modeling. A mixed modeling technique has been used to derive general expressions governing heat conduction and convection of MEMS thermal accelerometers. This technique is based on the use of results from FEM simulations to develop an analytical model where all derived expressions are as a function of biasing temperatures and key design geometry parameters. For conduction behavior analysis, two variables are being used in FEM simulations: heater temperature and micromachined cavity depth. The latter parameter has a large impact on the overall conductive behavior of thermal accelerometers since it fixes the volume where the heat bubble can expand. In addition, heater temperature is considered to be the only parameter that fixes heat distribution in the cavity. This modeling has led to the derivation of expressions for both heater heat transfer coefficient and common mode temperature. These physically-based derived expressions govern the overall sensor conductive behavior. Concerning heat convection behavior, cavity width parameter has been added as a third variable. Using simulation data points, fitting technique has been used to develop an analytical expression of differential temperature, proportional to sensitivity, as a function of the above design and temperature parameters. This study helps to predict sensor performance at an early design stage and more importantly for different sensor design geometries and temperatures.

J. Nebhen, S. Meillere, J-L. Seguin, K. Aguir, M. Masmoudi, H. Barthelemy

A Temperature Compensated CMOS Ring Oscillator For Wireless Sensoing Applications , Journal of Sign. Process. Syst. Vol. 72, No. 2 1, pp. 61-71, Aug 2013. DOI 10.1007/s11265-013-0794-7 , 2013-08-10
[Abstract]
Abstract
This paper presents a CMOS voltage controlled ring oscillator (VCO) with temperature compensation circuit suitable for low-cost and low-power MEMS gas sensor. This compensated ring oscillator is dedicated to Chopper Stabilized CMOS Amplifier (CHS-A). To operate at low frequency, a control voltage generated by a CMOS bandgap reference (BGR) is described and the measurement results of the fabricated chips are presented. The output voltage of the reference is set by resistive subdivision. In order to achieve small area and low power consumption, n-well resistors are used. This design features a reference voltage of 1 V. The chip is fabricated in AMS 0.35 ?m CMOS process with an area of 0.032 mm2. Operating at 1.25 V, the output frequency is within 200±l0 kHz over the temperature range of ?25 °C to 80 °C with power consumption of 810 ?W.

2012

J. Nebhen, S. Meillere, J-L. Seguin, K. Aguir, M. Masmoudi, H. Barthelemy

A Temperature Compensated CMOS Ring Oscillator For Wireless Sensing Applications , Journal of Electrical and Electronics Engineering, JEEE, Vol.2, Issue 1, pp. 1-10, Sep 2012. (ISSN 2250-2424) , 2012-09-01
[Abstract]
Abstract
This paper presents a CMOS voltage controlled ring oscillator (VCO) with temperature compensation circuit suitable for low-cost and low-power wireless sensing applications. To operate at low frequency, a control voltage generated by a CMOS bandgap reference (BGR) is described and the measurement results of the fabricated chips are presented. The output voltage of the reference is set by resistive subdivision. In order to achieve small area and low power consumption, n-well resistors are used. This design features a reference voltage of 1V. The chip is fabricated in AMS 0.35 ?m CMOS process with an area of 0.032mm2. Operating at 1.25V, the output frequency is within 200±l0kHz over the temperature range of -25°C to 80°C with power consumption of 810?W.

2011

J. Nebhen, S. Meillere, J-L. Seguin, K. Aguir, M. Masmoudi

Low Noise CMOS Chopper Amplifier for MEMS Gas Sensor , Lecture Notes in Computer Sciences, Springer 2011, volume 6752/2011, pp. 366-373 , 2011-09-01
[Abstract]
Abstract
We describe in this paper a low-noise, low-power and low-voltage analog front-end amplifier dedicated to high resistive gas sensor detection. A mobile sensor system for very low level signals such as gas spikes detection is required to implement with a scaled CMOS technology. For a key circuit of these systems, a Chopper Stabilization Amplifier (CHS) which

J. Nebhen, S. Meillere, J-L. Seguin, K. Aguir, M. Masmoudi, H. Barthelemy

Low Noise Micro-Power Chopper Amplifier for MEMS Gas Sensor , International Journal of Microelectronics and Computer Science, IJMCS, Vol. 2, No. 4, pp. 146-155 , 2011-05-10
[Abstract]
Abstract
In this paper, a low-noise, low-power and low voltage Chopper Stabilized CMOS Amplifier (CHS-A) is presented and simulated using transistor model parameters of the AMS 0.35 ?m CMOS process. This CHS-A is dedicated to high resistive gas sensor detection. The proposed CHS-A using Chopper Stabilization technique (CHS) exhibits an equivalent input referred noise of only 0.194 nV / Hz for a chopping frequency of 210 kHz under ±1.25 V supply voltage and 26.5 dB voltage gain. The inband PSRR is above 90 and the CMRR exceeds 120 dB. At the same simulation condition, the total power consumption is 5 ?W only.

2006

Mezghani B., Tounsi F., Smaoui S., Haboura K., El-Borgi S., Choura S. and Masmoudi M.

Modelling and Simulation of a new Micromachined Acoustic Sensor , TRENDS IN APPLIED SCIENCES RESEARCH, Academic Journals Inc., USA 1 (5), 456-466. , 2006-10-16
[Abstract]
Abstract
In this paper, we present modelling and simulation results of a new micromachined acoustic sensor. Equation derivation of the variable mutual inductance is summarized. Two attachment structures of the suspended membrane, the I-shaped and L-shaped beams, are modelled and simulated. Using a theoretical mechanical modelling, we get displacement values of 13.11µm and 68.82 µm, for the I-shaped and L-shaped beam design, respectively. With a numerical FEM design, displacement values of 12.7µm and 63.5 µm were found for the I-shaped and L-shaped beam design, respectively. Using the analogy between acoustic, mechanical and electrical domains, the dynamic behaviour of the microphone is modelled, then simulated and a corner frequency around 200 kHz is found. This same value is found when applying analytical dynamics principles to determine the equations of motion for the suspended membrane. A FEM analysis is conducted in order to validate this theoretical model. This sensor is analyzed for mechanical-thermal noise by modelling the suspended membrane with its mass-spring oscillator diagram. The damping factor is found to be 4x10-2 N s m-1, which gives a fluctuating force spectral density of 2.57x10-11 N Hz-1/2 and an A-weighted sound level of about 38 dB(A) SPL.

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B. Mezghani, F. Tounsi and M. Masmoudi

Convection Behavior Analysis of CMOS MEMS Thermal Accelerometers Using FEM and Hardee's Model , Springer Journal of Analog Integrated Circuits and Signal Processing, Vol. 78, Issue 2, Feb 2014, pp 301-311. , 0000-00-00
[Abstract]
Abstract
This paper presents convection behavior investigation of CMOS MEMS convective accelerometers using both analytical and FEM techniques. In a first part, a newly developed accelerometer 3D model is used in FEM simulations to model convection behavior as a function of design geometry and temperature. Using various sizes of two different cover shapes, sensitivity reading and its maximum position in cavity are found to be largely affected by both cover size and shape. In addition, a sensor with cavity width of 600 lm produces sensitivity saturation starting at a cavity depth of 200 lm, for both cover shapes. Using FEM data and curve fitting, differential temperature is claimed to be linearly linked to the effective heater temperature to the power of 1.7. Using the same cavity design and from computed heating efficiency values, we found that a 60 lm width heater offers the best efficiency. This cavity and heater designs give an optimal detector position of 120 lm from heater center along the sensitive axis. Moreover, dual axis accelerometers are found to be more power efficient than single axis ones. In the second part, we present Hardee’s spherical model and investigate its possible application on convective accelerometers. It is shown that inner and outer isotherms deformation, caused by accelerometer design and convection process, should be modeled by including sensor geometry parameters in the derived governing equations. Moreover, Hardee’s biasing temperature relation has to be revised if it is to be used for convective accelerometers.

Chokri Abdelmoula, Karim Jaber and Mohamed Masmoudi

Path tracking control of a driven mobile robot in a dynamic environment , International Journal of Engineering Intelligent Systems (Vol 29, Issue 2, 2014) , 0000-00-00
[Abstract]
Abstract
This paper deals with the problem of path tracking of a driven mobile robot in a dynamic environment, where the workspace is cluttered with unpredictably moving persons and objects. The multidisciplinary system was described in VHDL-AMS. A concept of virtual prototype makes possible the characterization and the optimization of the mobile robot. A robust adaptive controller is proposed using an adaptive control feed forward Neural Network technique. The proposed control scheme employs the adaptive control approach to make the tracking error as small as possible. This algorithm was developed as a model of the feed forward Neural Network for generalization and fast convergence. Moreover, this algorithm is designed for testing a new physical structure of mobile robot in different configuration of environment for autonomous navigation. This can be achieved when the robot must reach a distance on the right or on the left or go straight and also when persons and objects are in activity in the same environment. The performance of the proposed approach is demonstrated through a simulation and experimental results.

Chokri Abdelmoula, Hanen Rouabeh, Mohamed Masmoudi

Behavior Control of a New Designed Mobile Robot Based on Fuzzy Logic and Neuro Fuzzy Approaches for MonitoringWall , International Journal of Intelligent Engineering and Systems, Vol.6, No.3, pp: 17-26, 2013 , 0000-00-00
[Abstract]
Abstract
Abstract: This work describes the design and development of controllers based on artificial intelligence applied to a newly designed mobile robot type-vehicle to control behavior for monitoring wall. Two approaches have been developed and optimized to achieve this task. The first one is based on Fuzzy logic. This control algorithm combines different sensory information and provides a suitable control command allowing the mobile robot to follow the wall deviations. The second approach consists of the application of a hybrid-type Neuro-Fuzzy ANFIS controller for the same task. An important feature of this approach is that the controller combines the advantages of both Fuzzy logic and Neural Networks.The simulation results are presented and implemented with VHDL using ANFIS architecture.

Chokri Abdelmoula, Fakher Chaari and Mohamed Masmoudi

Real time algorithm implemented in Altera’s FPGA for a newly designed mobile robot Autonomous navigation and parallel parking , Multidiscipline Modeling in Materials and Structures Vol. 10 No. 1,pp. 75-93, 2014 , 0000-00-00
[Abstract]
Abstract
Abstract Purpose – The purpose of this paper is to propose a generic platform for a robotic mobile system, seeking to obtain a support tool for under-graduation and graduation activities. Another objective was to gather knowledge in the mobile robotic area in order to provide practical solutions for industrial problems. Design/methodology/approach – The proposed new integrated platform would serve as didactic material for many disciplines, shown to be an ideal platform to teach DC motor drives, stepper motor and motion-control systems. To reach this objective, the ability of the robot to plan its motion autonomously is of vital importance. The control of a mobile robot in dynamic and unstructured environments typically requires efficient processing of data/information to ensure precise navigation and many other applications. Path planning is also one common method of auto-navigation. After the computation of the shortest path, mobile robot can navigate safely and without occlusion. Findings – The developed platform is an integrated system for intelligent software middleware to coordinate many activities in the field of electric drives, robotics, autonomous systems and artificial intelligence. Originality/value – As a result of the study, this paper contributed to research in the industrial development, principally in the fields of industrial robotics and also in different application purposes such as entertainment, personal use, welfare, education, rehabilitation, etc. Keywords Artificial intelligence, Industrial robotics, Mobile robot, 3D measurement, Auto-navigation, Intelligent parking system Paper type Research paper

Chokri Abdelmoula, Fakher Chaari, Mohamed Masmoudi

A NEW DESIGN OF A ROBOT PROTOTYPE FOR INTELLIGENT NAVIGATION AND PARALLEL PARKING , Journal of Automation, Mobile Robotics & Intelligent Systems VOLUME 3, N° 2, pp:47-58, 2009 , 0000-00-00
[Abstract]
Abstract
Abstract Nowadays, the design of industrial vehicles and movable cars is based on the automation of their different tasks, which are currently handled by humans. These tasks, such as manoeuvring robots in complex environments, require high level of precision that cannot be guaranteed by humans. Manual operations are likely to produce errors of computation and optimization of navigation and manoeuvre (left, right, veering…). In this paper, a novel prototype of a well-structured robot for intelligent navigation and parallel parking applications is presented. The robot have two axels, the front one is composed of two wheels that are manoeuvred by a stepper motor, and a pinion rack system for controlling the rotation of the wheels, and also the orientation of the robot. The driving wheels are mounted in the rear axle of the robot and are commanded by two DC motors. The design allows modification of the robot structural components whenever required. In addition to the mechanical components, the prototype is equipped with a DC power supply, three infra-red sensors, one ultrasound sensor, and control modules composed of an FPGA card, microcontroller card and two cards which are responsible for commanding actuators. The parameters of the mechanical and electronics components are optimised to perform multiple tasks for training and instruction applications. A mathematical model that describes the dynamics of the robot prototype is also developed. Simulation, experimental and theoretical investigations were carried out consisting in navigation and parallel parking manoeuvres. It was confirmed that the experimental and theoretical results agree well in both applications. Keywords: autonomous vehicles, embedded design, and mobile robot.

Hanene Rouabeh, Chokri Abdelmoula, Mohamed Masmoudi

VHDL based Hardware Architecture of a High Performance Image Edge Detection Algorithm , International Journal of Computer Applications (0975 – 8887) Volume 91 – No.12, April 2014 , 0000-00-00
[Abstract]
Abstract
ABSTRACT This article presents the software and hardware implementation of a low cost and high performance image edge detection algorithm. This algorithm will be used as part of a complete vision based driver assistance system. The main challenge consists in realizing a real-time implementation of edge detection algorithm that contributes in increasing the performance of the whole system. The software implementation of the developed algorithm using MATLAB tool is discussed in this paper, as well as the hardware architecture developed using VHDL language. Test results for both implementations were presented and compared to other edge detection operators. Computational time and other features comparison have shown the effectiveness of the proposed approach. General Terms Computer science, Image processing, VHDL

Amel Neifar, Hatem Trabelsi, and Mohamed Masmoudi

An FSK Demodulator Design for RF Wireless Sensor Applications Using Zigbee Protocol , International Journal of Electronics and Electrical Engineering Vol. 3, No. 4, August 2015 , 0000-00-00
[Abstract] [Full Text]
Abstract
In this paper, transistor-level simulations of a detector called “cross-differentiate-multiplier demodulator (CDM)” are presented. This detector, which uses three blocks (a differentiator, a multiplier and a subtractor), is able to demodulate a received bit sequence, that was transmitted using a frequency-shift keying modulation scheme, with a bit rate equal to 20kbps. The application of this detector will be in a wireless sensor receiver operating in the 863-870MHz ISM band. In this sensor, a frequency hopping spread spectrum is used as modulation technology and Zigbee (IEEE 802.15.4) as the communication protocol. Design is performed using 0.35?m CMOS technology and a 3V supply. A comparison between the performances of different architectures studied, mainly in terms of BER, is presented at the end of this document.