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CAD-oriented HEMT models from noise and scattering measurements
Full text linkThe simultaneous determination of noise, gain and scattering parameters by means of a computer-driven noise figure test-set allows the rapid and accurate characterization of some samples of HEMTs of the same series. An equivalent circuit model representing the behavior of the typical device then is extracted by means of a decomposition approach. Comparison between the model performance and the measured parameters of all devices are reported for the FHR 02FH (by Fujitsu). The modeling procedure is oriented to CAD of (M)MIC low noise amplifiers
Guest editorial for the special issue on noise modeling of high-frequency semiconductor devices
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A global approach to the noise and small-signal characterization of microwave field-effect transistors
No full textExperimental investigation of the kink effect and the low frequency noise properties in pseudomorphic HEMTs
No full textThe 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 onset within the channel. In addition, the low frequency gate and drain noise has been measured at bias conditions below and above the kink to analyze its correlation with the processes involving discrete energy trap states. A Lorentzian noise contribution has been found in the drain noise spectrum traced at kink bias V-DS,V-kink with a corner frequency corresponding to that exhibited by the output conductance dispersion curve at the same bias. Thus, the devices under test classified as short-channel low-voltage GaAsFET's exhibit a marked kink effect whose origin is likely to be due trapping mechanisms. (c) 2005 Elsevier Ltd. All rights reserved
Statistical modeling of pseudomorphic HEMTs from automated noise and scattering parameter measurements
No full textLangevin Approach to understand the Noise in Microwave Transistors
No full textA noise analysis procedure for microwave devices based on Langevin approach is presented.
The device is represented by its equivalent circuit with the internal noise sources
included as stochastic processes. Fromthe circuit network analysis a stochastic integral
equation for the output voltage is derived and fromits power spectrumthe noise figure
as a function of the operating frequency is obtained. The theoretical results have
been compared with experimental data obtained by the characterization of an HEMT
transistor series (NE20283A, by NEC) from6 to 18 GHz at a low noise bias point. The
reported procedure exhibits good accuracy, within the typical uncertainty range of any
experimental determination. The approach allows to extract all the information required
for a complete knowledge of the noise performance of the device without any restriction
on the statistics of the noise sources
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