Search results for "High-electron-mobility transistor"
showing 10 items of 12 documents
HEMT for low-noise microwaves: CAD-oriented performance evaluation
1995
This paper shows how a graphic processing of low-noise HEMT's small signal parameters, allows evaluating and comparing the actual performance obtainable in front-end applications. HEMT's tradeoff charts which solve tradeoffs among the basic low-noise amplifier performance are reported. Figures of merit for microwave low-noise HEMT which represent a fast way of evaluating HEMT in actual working conditions and of selecting the proper transistor, are defined. As an example, the tradeoff charts and the figures of merit of two HEMT's (Fujitsu FHR02FH, Sony 2SK677) and a pseudomorphic-HEMT (Celeritek CFB001-03) are reported and compared with the data sheets. © 1995, IEEE. All rights reserved.
Experimental investigation of the kink effect and the low frequency noise properties in pseudomorphic HEMT’s
2005
The kink effect in low-noise pseudomorphic (AlGaAs/InGaAs) HEMT's has been examined in detail by investigating the steady-state and pulsed I-V characteristics, the behavior of the output conductance dispersion and the performance of the gate leakage current to understand its origin. No clear evidence of impact ionization occurrence in the InGaAs channel at kink bias conditions (V-DS.kink = 1.5 V) has been found, thus suggesting that the predominant mechanism should be attributed to trap-related phenomena. A significant rise of the gate current has been found at very high drain voltages (far from V-DS.kink) associated with low drain current values which is probably due to impact ionization o…
Unstable behaviour of normally-off GaN E-HEMT under short-circuit
2018
The short-circuit capability of power switching devices plays an important role in fault detection and the protection of power circuits. In this work, an experimental study on the short-circuit (SC) capability of commercial 600 V Gallium Nitride enhancement-mode high-electron-mobility transistors (E-HEMT) is presented. A different failure mechanism has been identified for commercial p-doped GaN gate (p-GaN) HEMT and metal-insulator-semiconductor (MIS) HEMT. In addition to the well known thermal breakdown, a premature breakdown is shown on both GaN HEMTs, triggered by hot electron trapping at the surface, which demonstrates that current commercial GaN HEMTs has requirements for improving the…
Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs
2019
GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (R) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (R) characteristic…
DC and 1/f noise characterization of cryogenically cooled pseudomorphic HEMT's
2002
Pseudomorphic (AlGaAs/InGaAs/GaAs) HEMT's have exhibited the best noise performance over the entire LF-to-microwave frequency range if compared to MESFET's and conventional GaAs HEMT's, due to either a reduced flicker noise, a lower G/R contribution and a smaller high-field diffusion noise. We have recently investigated the microwave (up to 18 GHz) noise properties of packaged pseudomorphic HEMT's from 290 K down to cryogenic temperature values. The current experimental work is aimed at extending such analysis to the LF noise range and at low temperatures. Cryogenic noise spectra (1 Hz to 100 KHz) and DC characteristics have therefore been recorded and the relevant observations on the devic…
TEMPERATURE DEPENDENT NOISY MODELS OF PSEUDOMORPHIC HEMTs
1994
From a complete characterization in terms of noise and scattering parameters carried out at room temperature in the 8–16 GHz frequency range, the noisy small‐signal model of a pseudomotphic HEMT series has been extracted. The transistor scattering parameters have been subsequently measured at lower temperatures (down to −50 °C) by placing the device text fixture in a thermo‐controlled chamber. The model effectiveness has then been tested by determining the circuit element values at the different temperatures and by observing the model noise performance.
Temperature Dependence of pHEMT-Based LNA Performance for VSAT Applications
1994
From a complete characterization in terms of noise and scattering parameters carried out at room temperature in the 8-16 GHz frequency range, the noisy small-signal model of a pseudomorphic HEMT series has been extracted. The transistor scattering parameters have been subsequently measured at lower temperatures (down to -50 °C) by placing the device text fixture in a thermo-controlled chamber. An accurate noisy model has then been extracted by determining the circuit element values at the different temperatures. The trade-off performance of a pHemt-based LNA for VSAT receiver system applications has been investigated vs. frequency and temperature.
Typical Aspects of the Microwave Noise Performance of HEMTs at Decreasing Temperatures
1996
In analog signal processing at microwave frequencies the noise performance of active devices is of fundamental importance for the accurate design of low-noise amplifiers. To this aim, the determination of the four noise parameters F O , Γ O (complex variable) and Rn has to be accomplished together with the usual scattering parameter measurements vs. frequency. In addition, the dependence of the device performance vs. temperature is of interest for circuit applications characterized by harsh environmental conditions. In this work the noise behavior of high electron mobility transistors has been investigated by means of measurements and modeling in the 2-18 GHz frequency range and as a functi…
Fast and efficient procedures for determining the microwave noise parameters of HEMT's at decreasing temperatures
1998
Noise parameters are an electrical representation of the noise performance of transistors which is widely used in reliability studies as well as in the design of low-noise microwave amplifiers. Such parameters are usually determined by employing a complex indirect (standard) procedure based on multiple noise figure measurements and appropriate data processing techniques. We report here two altemative and rapid methods used to perform the complete noise characterization of HEMT's at decreasing temperatures over the 6 to 18 GHz frequency range. The results show a very satisfactory agreement.among the different procedures thus assessing the inherent consistency of the global approach to the pr…
Dynamic $\mathrm{R}_{\mathrm{ON}}$ evaluation of commercial GaN HEMT under different switching and radiation conditions
2019
This paper focus on the study of dynamic resistance $(\mathrm{R}_{\mathrm{dyn}})$ over commercial Gallium Nitride High Electromobility Transistors (GaN HEMTs) devices. The first part shows a study of the main mechanism causing $\mathrm{R}_{\mathrm{dyn}}$ , showing that depending on the structure, stress time, voltage applied and switching conditions, the $\mathrm{R}_{\mathrm{dyn}}$ can suffer a relevant increase. Also, it is demonstrated how the use of soft-switching conditions can alleviate trapping effects. Finally, due to the interest over these devices for future space applications, the effects of gamma radiation over the $\mathrm{R}_{\mathrm{dyn}}$ has been studied.