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Proceedings Paper

Comparison of the noise performance of MODFET's
Author(s): Brian Hughes
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Paper Abstract

The frequency dependencies of minimum noise figure (Fmin) and associated gain (Ga) of extrinsic MODFETs have been fit with the resistor temperature noise model for intrinsic FETs of Pospieszalski. The noise model for extrinsic MODFETs has two fitting parameters; an effective fmax and an effective output resistor temperature (Td) which are extracted directly from the measured Fmin and Ga. A comparison of noise results in more than 50 publications shows that the majority of MODFETs can be modelled with a small range of effective Td values between 300 and 700 K. AlInAs/GaInAs/InP MODFETs exhibit significantly lower Fmins and Gas than conventional AlGaAs/GaAs and AlGaAs/InGaAs pseudomorphic MODFETs of the same gate length. The reason is InP-based MODFETs have a much higher average fmax(DOT)Lg at low noise bias. The noise model implies that in addition to a high fT and low Rin, a lower Gds also reduces Fmin. Also, it suggests that the Fukui fitting factor (Kf) is proportional to the inverse square root of the voltage gain. Recent experimental results support this suggestion. The noise model and the analyses of published results show that a higher fmax at low noise bias is a key factor for a lower Fmin and a higher Ga.

Paper Details

Date Published: 3 September 1992
PDF: 11 pages
Proc. SPIE 1680, High-Speed Electronics and Optoelectronics, (3 September 1992); doi: 10.1117/12.137718
Show Author Affiliations
Brian Hughes, Hewlett-Packard Co. (United States)


Published in SPIE Proceedings Vol. 1680:
High-Speed Electronics and Optoelectronics

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