Millimeter-wave low-noise high electron mobility transistors

High electron mobility transistors (HEMT's) have been fabricated which demonstrate excellent millimeter-wave performance. A maximum extrinsic transconductance as high as 430 mS/mm, corresponding to an intrinsic transconductance of 580 mS/mm, was observed in these transistors. A unity current gain cutoff frequency f
T
as high as 80 GHz and a maximum frequency of oscillation
f_{\max}
of 120 GHz were projected for these HEMT's. At 40 GHz, a minimum noise figure of 2.1 dB with an associated gain of 7.0 dB has also been measured. These are the highest
f_{T}, f_{\max}
, and the best noise performance reported to date. The results clearly demonstrate the potential of HEMT's for millimeter-wave low-noise applications.