A nonuniform thermal de-embedding approach for cryogenic on-wafer high-frequency noise measurements

A methodology to perform accurate on-wafer high-frequency noise measurements at cryogenic temperatures (77K) is presented. In this work, the distribution of the temperature along probes and cables at low temperatures is carefully taken into account in the de-embedding process using a 3-D thermal modelling software (®ANSYS) and thermal measurements. Cables and probes are modelled in ®ADS software using a distributed RLCG network associated to this temperature distribution. The validity of this model has been checked by measuring the noise power of a 50 Ω on-wafer resistance placed at several low temperatures. Finally, we apply this technique to the noise characterization of sub-100 nm gate´s length MM-HEMT at 77K and 173K.