5-40 GHz S-Parameter Measurements at 20 K for Accurate Design of Low-Noise Cryogenic HEMT Amplifiers

This paper discusses S-parameter measurements of the Fujitsu FHR10X HEMT at 20 K and up to 40 GHz under varied bias conditions. To the best of our knowledge, this is the first report of such measurements in the millimeter-wave band at cryogenic temperatures. The performance of the Ka-band amplifiers we designed using these measurements proves that this measurement technique is useful in designing amplifiers accurately.