Low-Temperature Performance of Nanoscale MOSFET for Deep-Space RF Applications

RF characteristics of a nanoscale MOSFET are measured and analyzed at temperatures ranging from 4.2 to 300 K for deep-space RF applications. This device shows a 197-GHz current gain cutoff frequency (f
_T
) and a 162-GHz maximum oscillation frequency (f
_max
) when operating at liquid-helium temperature, which represent a 60% and 80% improvement compared to room temperature performances, respectively, f
_T
continually improves as the temperature decreases to near-liquid-helium temperature due to the decrease of gate capacitance (C
_gg
). f
_max
decreases as the temperature is lowered below 25 K due to the increase of gate resistance (R
_g
).