Title :
Importance of source and drain resistance to the maximum f/sub T/ of millimeter-wave MODFETs
Author :
Tasker, Paul J. ; Hughes, Brain
Author_Institution :
Sch. of Electr. Eng., Cornell Univ., Ithaca, NY, USA
fDate :
7/1/1989 12:00:00 AM
Abstract :
The usual approximate expression for measured f/sub T/=(g/sub m//2 pi (C/sub gs/+C/sub gd/)) is inadequate. At low drain voltages just beyond the knee of the DC I-V curves, where intrinsic f/sub t/ is a maximum for millimeter-wave MODFETs, the high values of C/sub gd/ and G/sub ds/ combine with the high g/sub m/ to make terms involving the source and drain resistance significant. It is shown that these resistances can degrade the measured f/sub T/ of a 0.30- mu m GaAs-AlGaAs MODFET from an intrinsic maximum f/sub T/ value of 73 GHz to a measured maximum value of 59 GHz. The correct extraction of maximum f/sub T/ is essential for determining electron velocity and optimizing low-noise performance.<>
Keywords :
III-V semiconductors; aluminium compounds; electric resistance; gallium arsenide; high electron mobility transistors; solid-state microwave devices; 59 GHz; 73 GHz; DC I-V curves; EHF; GaAs-AlGaAs; III-V semiconductors; MM-wave HEMT; drain resistance; electron velocity; low drain voltages; low-noise performance; maximum f/sub T/; microwave device; millimeter-wave MODFETs; source resistance; Current measurement; Electrical resistance measurement; Gallium arsenide; HEMTs; Knee; Low voltage; MODFETs; Microwave technology; Millimeter wave measurements; Scattering parameters;
Journal_Title :
Electron Device Letters, IEEE
