On-Wafer Cryogenic RF Noise Measurement Techniques

This paper introduces two RF noise measurement methods suitable for probe-based, on-wafer, IC characterization at cryogenic temperatures. The first method requires only one cool down step and is based on multiple calibration and power measurements. The second method requires two cool down steps as well as multiple calibration and NF measurements. A 6.5 GHz cryogenic LNA IC was used to evaluate and compare both methodologies. In the frequency range of 5.5 GHz to 8.5 GHz, the maximum measured discrepancies in noise temperature and gain between both methods are 3 K and 0.5 dB respectively. The results from these on-wafer measurements are also in good agreement with connectorized measurements performed on a packaged LNA.