Maher Kayal

LAYIN: toward a global solution for parasitic coupling modeling and visualization

A CAD tool dedicated to parasitic substrate coupling modeling and visualization is presented. A CIF representation of the layout and a specific technology description are used to extract a simple parasitic substrate coupling model. The output is SPICE compatible and includes a geometrical information that is used to show on the layout the distribution of the equipotential lines produced by a perturbing source. Results are compared with measurements and other simulators to demonstrate the accuracy of the model.<<ETX>>

A Hall Sensor Analog Front End for Current Measurement With Continuous Gain Calibration

This paper presents a new technique for continuously calibrating the sensitivity of a current measurement microsystem based on a Hall magnetic field sensor. An integrated reference coil generates a magnetic field for calibration. Using a variant of the chopper modulation, the spinning current technique, combined with a second modulation of the reference signal, the sensitivity of the complete system is continuously measured without interrupting normal operation. Modulation and demodulation schemes allowing the joint processing of both external and reference magnetic fields are proposed. Additional techniques for extracting the very low reference signal are presented. The implementation of the microsystem is then discussed. Finally, measurements validate the calibration principle. A thermal drift lower than 50 ppm/degC is achieved. This is 6-10 times less than in state-of-the-art implementations. Furthermore, the calibration technique also compensates drifts due to mechanical stresses and ageing

Highly sensitive Hall magnetic sensor microsystem in CMOS technology

A highly sensitive magnetic sensor microsystem based on a Hall device is presented. This microsystem consists of a Hall device improved by an integrated magnetic concentrator and new circuit architecture for the signal processing. It provides an amplification of the sensor signal with a resolution better than 30 /spl mu/V and a periodic offset cancellation while the output of the microsystem is available in continuous time. This microsystem features an overall magnetic gain of 420 V/T.

SALIM: a layout generation tool for analog ICs

The authors present a system for analog layout generation of integrated microcircuits (SALIM). The program, which combines a set of algorithms with a knowledge base, features two working modes: automatic and interactive. In the automatic mode, a knowledge-based expert system drives the algorithms. In the interactive mode, the designer task is reduced to the choice of basic elements and their association sequence.<<ETX>>

Optimization of Shielded PCB Air-Core Toroids for High-Efficiency DC–DC Converters

The paper describes the design of optimized printed circuit board (PCB) air-core toroids for high-frequency dc-dc converters with strict requirements in terms of volume and noise. The effect of several design parameters on the overall inductor volume, on dc and ac winding resistance, and on the radiated noise will be investigated. PCB toroids are compared to standard air-core solenoids and other state-of-the-art air-core toroids both theoretically and experimentally: at first, using ANSOFT Maxwell and ANSOFT Q3D simulation tools, and subsequently, with laboratory measurements (irradiated noise, efficiency, and frequency response) on several prototypes. These very flexible and rather easy to manufacture inductors appear very attractive for compact high-frequency dc-dc converters where high efficiency, low volume, and low noise are of primary concern.

Global Modeling Strategy of Parasitic Coupled Currents Induced by Minority-Carrier Propagation in Semiconductor Substrates

This paper presents a modeling strategy to simulate the propagation of electrical perturbations induced by direct biasing of substrate junctions. Usually, this is done by identifying parasitic substrate devices such as bipolar transistors. However, mapping a topology with these bipolar transistors rapidly reaches its limits when several junctions are acting at the same time. In this paper, we propose a new modeling methodology of parasitic signals. It relies on a generalized model of p-n junctions and resistances that takes into account minority-carrier densities and gradients at the boundaries. We show that bipolar-transistor- and thyristor-related effects can be obtained from a network interconnection of these extended devices. Furthermore, we show that this modeling approach could be easily extended to simulate complex 3-D layouts.

A Hall sensor analog front end for current measurement with continuous gain calibration

This paper presents a new technique for continuously calibrating the sensitivity of a current measurement microsystem based on a Hall magnetic field sensor. An integrated reference coil generates a magnetic field for calibration. Using a variant of the chopper modulation, the spinning current technique, combined with a second modulation of the reference signal, the sensitivity of the complete system is continuously measured without interrupting normal operation. Modulation and demodulation schemes allowing the joint processing of both external and reference magnetic fields are proposed. Additional techniques for extracting the very low reference signal are presented. The implementation of the microsystem is then discussed. Finally, measurements validate the calibration principle. A thermal drift lower than 50 ppm/degC is achieved. This is 6-10 times less than in state-of-the-art implementations. Furthermore, the calibration technique also compensates drifts due to mechanical stresses and ageing

Automatic calibration of Hall sensor microsystems

In many applications, a Hall element is used for contact-less measurement such as linear and angular positions, electrical current, power and energy, etc. The Hall element fabricated by means of CMOS technology features mediocre characteristics [R.S. Popovic, Z. Randjelovic, D. Manic, Integrated Hall-Effect Magnetic Sensors, EMSA, Germany, 2000; R.S. Popovic, Hall Effect Devices, Adam Hilger, Bristol, Philadelphia, New York, 1991]. It gives a weak output signal of the order of a few mV. This signal is often corrupted by sensor offset, noise, temperature and aging drift. This paper deals with the state of the art and main techniques capable to detect and compensate these issues. Case studies using mentioned techniques are also summarized.

A hall sensor-based current measurement microsystem with continuous gain calibration

A novel technique for the continuous calibration of the sensitivity of Hall sensors is presented. Using an integrated coil and a new modulation/demodulation scheme, the sensitivity is measured and its drift eliminated. The obtained thermal drift is 50 ppm/degrees C, which corresponds to a reduction by a factor of 6-10 compared to the previous state of the art. The sensitivity drift due to purely mechanical stresses and ageing is also cancelled.

Optimization of shielded PCB air-core toroids for high efficiency dc-dc converters

The paper describes the design of optimized PCB air-core toroids for high frequency DC-DC converters with strict requirements in terms of volume and noise. The effect of several design parameters on the overall inductor volume, on DC and AC winding resistance, and on the radiated noise will be investigated. PCB toroids are compared to standard air-core solenoids and other state-of-the-art air-core toroids both theoretically and experimentally: at first using ANSOFT Maxwell and ANSOFT Q3D simulation tools, subsequently with laboratory measurements (irradiated noise and efficiency) on several prototypes. These very flexible and rather easy to manufacture inductors appear very attractive for compact high frequency DC-DC converters where high efficiency, low volume and low noise are of primary concern.