Pascal Dherbecourt

A 5000 h RF life test on 330 W RF-LDMOS transistors for radars applications

A reliability test bench dedicated to RF power devices is used to improve 330 W LDMOS in a radar conditions. The monitoring of RF power, drain, gate voltages and currents under various pulses and temperatures conditions are investigated. Numerous duty cycles are applied in order to stress LDMOS. It shows with tracking all this parameters that only few hot carrier injection phenomenon appear with no incidence on RF figures of merit (Pout or PAE). Robustness and ruggedness are shown for LDMOS with this bench for radar applications in L-band.

Achieving of an optical very high frequency modulated wave source using heterodyne technique

We describe a method for generating an amplitude modulated optical wave in the range of the telecommunication frequencies. The originality is to guaranty a tunability of the source up to 275 GHz with about 45 MHz spectral width. The principle is based on the optical heterodyne of two DFB laser sources emitting around 1550 nm. After describing various existing methods for optical wave modulation and for millimetric signal generation, we concentrate our interest on the heterodyne technique. We carry out a study concerning the spectral width influence on the spectral purity of the generated signal. Then, the experimental measurement set-up is described, as well as characterization of the spectral width of the lasers. Finally, we present the results obtained in reception of the beat of two identical lasers on a 25 GHz bandwidth photodiode.

Characterization and modeling of hot carrier injection in LDMOS for L-band radar application

Abstract This paper reports a methodology to correlate Hot Carrier Injection (HCI) degradation mechanism and electrical figures of merit on Lateral-Diffused Metal–Oxide-Semiconductor (LDMOS) transistor. This method is based on RF life test in radar operating conditions coupled to a high drain voltage in order to make visible HCI degradation. We propose drain current modeling vs. time based on a simple extraction procedure. The electron density trapped in the oxide is extracted from hot carrier induced series resistance enhancement model (HISREM – i.e. Δ R d model). From this methodology, the degradation of RF-LDMOS due to HCI is quantified and could be simulated with EDA.

Generation of an amplitude modulated optical wave up to 275 GHz by laser wave mixing for optical component bandwidth measurement

This paper presents a method to achieve an amplitude-modulated optical wave in the range of telecommunication frequencies for optical components bandwidth tests. The principle is based on the optical heterodyning of two free distributed feedback lasers. The frequency tunabil- ity of the modulated wave reaches 275 GHz with high stability. These characteristics constitute the originality of our work. Our laboratory has developed an experimental fusion setup that enables the realization of numerous optical fiber components. Component bandwidth measurement enables their validation for high-rate data transmissions. We present in this paper results obtained for a 57-GHz beat signal in a fast photodiode and we describe bandwidth optical components tests in the 0 to 40 GHz range.

Simulation and Experimentation of an RFID System in the UHF Band for the Reliability of Passive Tags

This paper presents the simulation of a UHF RFID (Radio Frequency Identification) system for passive tags, using Advanced Design System software from Agilent Company. Temporal measurements based on a commercial RFID reader are achieved which permit to analyze and to validate the principles of communication between the reader and the tag. Also a test bench is developed to evaluate the effects of high temperature on the reliability of passive UHF RFID tags. The obtained test results show that the thermal storage has a marked effect on the performances of the RFID tags.

Gate oxide degradation of SiC MOSFET under short-circuit aging tests

SiC MOSFETs reliability issues remain a challenge that requires further investigation. In this article, a short-circuit aging test was developed to characterize the electrical parameter evolution. The threshold voltage and gate drain capacitance seem to be relevant degradation indicators. These two parameters indicate a gate oxide degradation. Electron trapping in the oxide layer could be the mechanism behind this deterioration.

New approach for thermal investigation of a III – V power transistor

In this paper is presented a new method for characterisation of temperature of AlGaN-GaN transistor. An ellipsometer is also explained for measure of refractive index and so propagation time constant.

Evolution of C-V and I-V characteristics for a commercial 600 V GaN GIT power device under repetitive short-circuit tests

Abstract In this article, a repetitive and non-destructive short-circuit aging test is developed to characterize the electrical parameters evolutions of a 600 V GaN Gate Injection Transistor (GIT). The evolutions of C-V and I-V characteristics during the repetitive short-circuit tests with a relatively low bias voltage and long pulse duration are presented and summarized. The capacitance CGD at on-state mode and the gate current at relative high gate voltage show significant degradations before and after test.

Short-circuit robustness test and in depth microstructural analysis study of SiC MOSFET

Abstract The purpose of this paper is to describe an approach of short circuit ageing allowing further microstructural analysis that is needed for the identification of failure mechanisms. So far, few relevant studies on SiC MOSFET SC robustness tests have been described putting in light the need for complementary information on physical mechanisms involved in failure modes. A large part of this work is dedicated to a new approach of SC robustness tests. Following ageing, using PEM (Photo Emission Microscopy) technique, SEM (Scanning Electronic Microscopy), and FIB (Focus Ion Beam) cutting, the study successfully correlates electrical measurements and structural analyses for an elementary cell of SiC MOSFET power transistor.

Reliability and Failure Analysis of UHF RFID Passive Tags Under Thermal Storage

This paper proposes studying the effects of thermal storage on the reliability of passive ultra-high frequency radio-frequency identification tags. Two types of tags M1 and M2 from two different manufacturers are aged under two high temperatures equal to 408 K and 433 K. Tested tags are put into thermal storage oven hang fixed terms. The performances of these tags are measured after each aging phase to determine the power loss caused by high-temperature storage. Then, a mathematical approach is used to estimate for both tags from the two manufacturers the law of reliability under nominal conditions. Statistical and physical analyses of the results allow us to study and analyze the mechanisms of aging. It is observed that the failure mechanisms depend on the type of passive tags and the values of selected storage temperatures for the tests. The scale parameters of M1 tags aged at 408 K are around 280 h, whereas the scale parameters of the M2 tags aged at the same temperature are around 360 h. Cracks on the antenna are observed with the higher temperature equal to 433 K for M1 tags. However, the changes of the performance of others tags are probably caused by changes in the matching of the impedance between the antenna and the radio-frequency integrated circuit. From this study, various failure mechanisms demonstrate the necessity of determining the type of passive tags and the used temperature.