A fast and functional technique for the noise figure measurement of differential amplifiers

This paper presents an original technique to measure the noise figure of differential amplifiers with a four-port network analyzer. The approach is fast and simple as the S-parameters and the output noise powers are measured directly with the analyzer. There is no need of hybrid couplers or baluns. The measurement procedure and the test set-up are detailed in the paper. And to illustrate the usefulness of this new approach, measurement results of a radio-frequency differential amplifier are presented and compared to the results obtained with state-of-the-art techniques.