Noise characteristics of a cryogenically cooled GaAs metal semiconductor field effect transistor at 4 MHz

The noise near 4 MHz of a cryogenically cooled GaAs metal semiconductor field effect transitor (MESFET) has been measured. The input noise current is iN=1.1±0.2×10−14 A/(Hz)1/2 and the additive voltage noise is eN=1.2±0.4×10−9 V/(Hz)1/2 , which gives a noise temperature TN=0.5 K.