Characterization of a Cryogenic RF-Preamplifier for Superconducting Photodetector Readout

This work addresses the problem of designing superconducting photodetector readout circuits. A preliminary investigation of a selection of commercially available components to implement a radio-frequency, broadband, low-noise preamplifier operated in a cryogenic environment is presented. Wide band, high gain, low noise and stability under input mismatching load conditions have been the leading criteria taken into account to choose the devices. A set of monolithic microwave integrated circuits (MMIC) based on different technologies (GaAs, InP, HEMT, HBT) has been considered. The prototypes have been characterized at room temperature and low temperature by means of a cryocooler; their main parameters, gain and noise figure, have been measured.