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Etude et modélisation des transistors à effet de champ microondes à basse température. Application à la conception d'oscillateurs à haute pureté spectrale

Abstract : The aim of the present work is to define a rigorous method allowing the design of low phase noise microwave oscillators based on field effect transistors (MESFET, HEMT and pseudomorphic HEMT) including in the case where the transistor and the resonator are both cryogenically cooled. In a first part, a complete electrical characterization of different type of FET at liquid nitrogen temperature is presented. The emphasis is put on trapping-detrapping mechanisms on deep levels and a method is proposed to circumvent the collapse phenomenon which is the more serious drawback of device cooling. Then, S parameters and pulsed measurements have been used to extract a large signal model for each transistor. In a second part, the conversion process of low frequency noise into phase noise in FET oscillators is investigated. The influence of the microwave signal on the LF noise spectrum amplitude and shape is reported. Next, the oscillator's frequency noise is analysed in terms of the FET's low frequency noise multiplied by the oscillator's pushing factor. The inaccuracy of this method at some particular gate bias voltages where the pushing factor decreases to zero is demonstrated. Consequently, a new nonlinear FET model involving at least two noise sources distributed along the channel is proposed. The last section of this work is dedicated to the realization and the characterization of a cryogenic FET oscillator.
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https://tel.archives-ouvertes.fr/tel-00010074
Contributor : Emilie Marchand <>
Submitted on : Thursday, September 8, 2005 - 3:06:01 PM
Last modification on : Friday, January 10, 2020 - 9:08:09 PM
Long-term archiving on: : Tuesday, September 7, 2010 - 5:24:14 PM

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  • HAL Id : tel-00010074, version 1

Citation

Jacques Verdier. Etude et modélisation des transistors à effet de champ microondes à basse température. Application à la conception d'oscillateurs à haute pureté spectrale. Micro et nanotechnologies/Microélectronique. Université Paul Sabatier - Toulouse III, 1997. Français. ⟨tel-00010074⟩

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