On-wafer LNA noise measurements for cryogenic LNAs

Applications in radio astronomy and quantum computing require microwave cryogenic low noise amplifiers with as low of noise as possible. Characterization of these devices requires special approaches, which require careful calibration and traditionally have not been compatible with on-wafer measurement. As activity in quantum computing has grown, interest in on-wafer cryogenic noise measurements has followed. In this talk, I will first review methods for coaxial cryogenic noise measurement. I will then present two approaches to on-wafer cryogenic noise measurement and explain how these methods can be applied to characterize cryogenic LNAs while achieving uncertainties on the order of +/- 1K. The first method employs a cryogenic attenuator in conjunction with a room temperature noise source whereas the second method employs a novel cryogenic noise source. The talk will conclude with a brief discussion of how these approaches may be employed in future build-in-self-test systems.