Charles Joubert

Gate Oxide Degradation of SiC MOSFET in Switching Conditions

Under realistic switching conditions, SiC MOSFETs reliability issues remain as a challenge that requires further investigation. In this letter, a specific aging test has been developed to monitor and characterize the electrical parameters of the SiC MOSFET. This allows estimations of the health state and predictions of the remaining lifetime prior to its failure. The gate leakage current seems to be a relevant runaway parameter just before failure. This leakage indicates deterioration of the gate structure. This hypothesis has been validated through analysis of scanning electron microscopy pictures, with a focused ion beam cut showing cracks within the polysilicon.

Magnetic Behavior Representation Taking Into Account the Temperature of a Magnetic Nanocrystalline Material

The aim of this study consists in modeling the magnetic behavior of a nanocrystalline material, taking into account temperature variation. Indeed the development of power electronic embedded systems leads to increase the operating temperature range. Besides nanocrystalline material is used more and more in such systems, so temperature influence is a key point in the magnetic component design.

Modeling, Fabrication, and Characterization of Planar Inductors on YIG Substrates

This paper presents the design, fabrication, and characterization of micro planar inductors on a microwave magnetic material (YIG). Planar spiral inductors were designed for monolithic DC-DC converters in System-In-Package with 100 MHz switching frequency (1 W, Vin= 3.6 V, Vout= 1 V). A microwave magnetic substrate (YIG) serves as mechanical support, and also presents a double purpose by increasing inductance value and reducing electromagnetic interferences (EMI). This last point is critical to improve the behavior of a switching mode power supply (SMPS). In order to obtain an optimal design for the inductor, geometrical parameters were studied using Flux2D simulator and an optimized 30 to 40 nH spiral inductor with expected 25 mΩ RDC, 3 mm2 footprint area was designed. Subsequently, samples have been fabricated by electroplating technique, and tested using a vector network analyzer in the 10 MHz to 100 MHz frequency range. Results were then compared to the predicted response of simulated equivalent model.

Online health monitoring of metallized polymer film capacitors for avionics applications

Metallized polymer film capacitors, assuming a special position among the various types of capacitors thanks to their capabilities to self-heal, became the components of choice for critical power electronics applications requiring optimized performances such as, avionics, automotive and railways equipments. However, as a result of the increasingly growing demand for guaranteeing safety and enhancing reliability, a greater interest has been devoted to the health monitoring of power electronics devices. In this paper, an online health monitoring approach for metallized film capacitors is proposed based on the estimation of their precursor parameters. The proposed technique makes use of the already existing current, voltage and temperature sensors for the power drive command/control purposes, and do not need the injection of additional external signals. To demonstrate and validate the effectiveness of such technique, the resulting algorithm was simulated on a set of capacitors at different degradations rates with Matlab/Simulink software. In this paper is also presented a novel “PEN type” polymer. This high-temperature polymer has great advances over the standard polymers films providing excellent self-healing capability with an enhanced energy density, making it one of the most compact film capacitors on the market.

Investigation of Using SiC MOSFET for High Temperature Applications

Abstract This paper presents the performances expected by SiC MOSFETs for high temperature applications. A complete static and dynamic electrical characterization of SiC MOSFETs have been tested under varying temperature from 25°C to 250°C using suitable packaging materials. To go further, aging tests have been performed to evaluate lifetime of SiC MOSFET under switching condition up to 300°C.

High temperature, high frequency micro-inductors for low power DC-DC converters

The development of micro-inductors is still a challenge to improve the integration level of low power DC-DC converters. The temperature rise due to self-heating or higher ambient temperature represents a risk for system operation. Unfortunately, the use of a heat sink increases the size of the converter and it is more difficult to extract the heat flow dissipated from a smaller area. The increase in the allowable operating temperature offers a solution to achieve a high integration level while ensuring proper heat management. This paper presents the fabrication process of micro-planar inductors with magnetic layers (YIG). The influence of the temperature on the magnetic material and on the inductor performances is studied up to 280 °C. Fabricated micro-inductors are tested using a LCR meter in the 10 kHz to 110 MHz frequency range and over a large temperature range, from 30 °C to 280 °C.

Micro-Fabrication of Planar Inductors for High Frequency DC-DC Power Converters

The inductors are essential elements for radiofrequency (RF) integrated circuits. A large number of communication devices functioning in RF such as mobile phones or wireless ethernet require transceivers, filters and power amplifiers in which inductors are critical components. Recently, the push toward miniaturisation of electronic components enabled to embark more and more portable equipments and accessories of high energy consumption. Embedded systems used in these devices are facing energy shortage that leads designers to spread power electronic converters to achieve dynamic voltage and frequency scaling [Zhao]. Wherever it is possible, the linear low-drop converter is replaced by inductive DCDC converters and/or capacitive DC-DC converters in order to improve the whole efficiency of the system. Since then the demand on power converters for portable electronic devices has attracted great interest [Sugawara]. Efficiency and footprint (or volume) are the main design criteria to ensure respectively a large operating range and a smaller device. These applications use switching mode power supply (SMPS) or inductive DC-DC converter which typically require the following characteristics: 1 W, VIN=3.6 V, VOUT=1 V, IOUT=1 A. Passive components fill a significant part of the chip area occupied by power converters, even when the components are optimized for minimum area. Thus, for this power range, System-In-Package (Fig. 1) is more appropriate than monolithic integration (also named System-On-Chip).