Y. Crosnier

Breakdown analysis of an asymmetrical double recessed power MESFET's

FETs with double stepped gate recess are commonly admitted to be presently a very convenient structure capable to overcome the fundamental power limitation related to the breakdown voltage. The present paper deals with an analysis of a double recessed MESFET with a very good and instructive breakdown performance. For the first time we explain on the basis of gate current observations why the double recess structure allows a large breakdown improvement not only at pinch off voltage but also at open channel. Moreover it is shown that the breakdown optimization is fully compatible with the microwave gain performance. >

Large signal model for analysis and design of HEMT gate mixer

This paper examines the problem of modeling HEMTs for calculations of conversion gain and intermodulation. An accurate and simple large signal model of discrete HEMTs has been developed. The nonlinear elements of the model are assumed to depend exclusively on the gate-source voltage. The interpolation of the measured data, using polynomial expressions, provides a description of the HEMTs nonlinearities in a CAD software. Based on the model, a hybrid HEMT gate mixer has been built. The accuracy of the model has been verified, and we obtained good agreement between the measured and simulated results.<<ETX>>

Characterization of GaAs and InGaAs double-quantum well heterostructure FETs

It is pointed out that among the large variety of heterostructure field effect transistors, multichannel devices present a particular originality: their transconductance profile is very flexible and depends on the structure parameters. They are therefore suited for high signal nonlinear applications. The specific case of double quantum-well structures is studied. Conventional and pseudomorphic devices are characterized under DC and RF conditions. Very high current densities (up to 1.2 A/mm) are demonstrated. The effect of different structural parameters on the transconductance and cutoff frequency is discussed. The results are analyzed in order to give a full understanding of these devices and to demonstrate their performances. >

Analysis of the source inductance effect on the power performance of high development HEMTs in the Ka-Band

This paper provides an analysis of the power performance degradations of interdigitated HEMTs in millimeter wave range as the total gate width increases. It investigates the possibility of optimizing the device topology by combining a limited number of via holes and airbridge source connections in order to offer a good cost-performance trade off. >

60 GHz MMIC mixer using a dual-gate PM HEMT

A Dual-Gate PM HFET monolithic mixer has been developed, fabricated and measured at 60 GHz. This circuit uses a 0.15 /spl mu/m gate length AlGaAs/InGaAs/GaAs pseudomorphic HEMT technology. The design optimization is performed from a complete extraction method of the dual-gate device and a non-linear electrical modeling. The mixer has a maximum conversion gain of -5 dB, a minimum noise figure of 11 dB at 5 dBm LO power, an output IMP3 of -2 dBm and a LO to RF isolation close to 35 dB.

Microwave Characterization of High T c Superconducting YBaCuO Thin Films and Preliminary Device Realization

High Tc superconducting thin films have been realized on MgO and LaAIO3 by laser ablation and sputtering. Their critical temperature are close to 90K. Their microwave properties have been tested on the one hand by the measurement of the complex conductivity (between 18 and 26 GHz) and on the other hand by realizing planar microstrip resonators.

Very non linear transconductance of highly delta-doped multichannel HEMTs

This paper presents the evolution with structural parameters of the linearity of the transconductance of multichannel HEMTs measured under low and microwave frequencies. Compared to theoretical calculations, the measured transconductance is in good agreement excepted at high doping levels. These discrepancies are attributed to parasitic effects. The discussion of the different possibilities brings us to conclude that the gate leakage current is most probably involved in the observed phenomena.

InP MISFET capabilities for microwave power amplification

A theoretical study to establish the behavior and the power amplification capabilities of the InP MISFET is described. Two numerical models are used. The first model is a two-dimensional simulation based on Poissons equation, and the current equation is supposed equal to zero. A second simulation uses a pseudo-two-dimensional model and entails a lighter computational burden. The validity of the results is verified by experimental measurements. Results obtained for the maximum drain current, the breakdown voltage, and the microwave properties show that the InP MISFET is a very interesting alternative for microwave power amplification.<<ETX>>

Étude du misfet InP en régimes d’enrichissement et d’appauvrissement pour amplification de puissance

Un modele pseudo bidimensionnel est propose afin d’etablir les possibilites dumisfetInP en regimes d’enrichissement et d’appauvrissement et une validation des resultats est obtenue a partir de resultats experimentaux On determine les caracteristiques courant de drain enfonction des tensions drain-source et grille-source ce qui permet d’estimer la valeur maximale du courant de drain et de la tension de claquage qui constituent des parametres importants pour des applications de puissance. De plus, on en deduit les principaux parametres de la structure ainsi que les performances hyperfrequences potentielles. Les resultats montrent que lemisfet InP constitue une possibilite tres interessante pour l’ amplification hyperfrequence de puissance.A pseudo two-dimensional model is proposed in order to describe the possibilities of the InPmisfet in enhancement and depletion modes, and a validation of the results is determined from experimental measurements. The drain current versus drain-source and gate-source voltages characteristics are established. They make possible to value the maximum drain current and the breakdown voltage which constitute important parameters for power applications. Moreover, the main device parameters and the determination of the potential microwave performances are deduced. The results show that the InPmisfet is a very interesting alternative for microwave power amplification.RésuméUn modèle pseudo bidimensionnel est proposé afin d’établir les possibilités dumisfetInP en régimes d’enrichissement et d’appauvrissement et une validation des résultats est obtenue à partir de résultats expérimentaux On détermine les caractéristiques courant de drain enfonction des tensions drain-source et grille-source ce qui permet d’estimer la valeur maximale du courant de drain et de la tension de claquage qui constituent des paramètres importants pour des applications de puissance. De plus, on en déduit les principaux paramètres de la structure ainsi que les performances hyperfréquences potentielles. Les résultats montrent que lemisfet InP constitue une possibilité très intéressante pour l’ amplification hyperfréquence de puissance.

Modélisation et comparaison de deux structures optimales AIGaAs/GaAs: Le transistor à effet de champ mis à canal dopé et le transistor à mobilité électronique elevée multicanal

Les auteurs presentent deux etudes approfondies concernant le transistor a effet de champmis a canal dope (dmt) et le transistor a mobilite electronique elevee (hemt) de puissance. Chaque travail comprend une premiere partie theorique ou la structure est optimisee par la simulation du composant. Des realisations technologiques ont ensuite ete elaborees au laboratoire. Les mesures effectuees donnent des resultats tres encourageants et laissent prevoir des performances superieures a celles desmesfet GaAs de puissance.We present two detailed studies concerning thedmt and the multichannelhemt for power amplifications. Each work comprises a first theoretical part where the structure is optimized by simulating the device. Technological realizations are hence performed at the laboratory. The following measurements give results very encouraging and permit to foresee the superior performance relatively to that of GaAs powermesfet.RésuméLes auteurs présentent deux études approfondies concernant le transistor à effet de champmis à canal dopé (dmt) et le transistor à mobilité électronique élevée (hemt) de puissance. Chaque travail comprend une première partie théorique où la structure est optimisée par la simulation du composant. Des réalisations technologiques ont ensuite été élaborées au laboratoire. Les mesures effectuées donnent des résultats très encourageants et laissent prévoir des performances supérieures à celles desmesfet GaAs de puissance.