A high-speed cryogenic SiGe channel combiner IC for large photon-starved SNSPD arrays

In this paper, the design and characterization of a cryogenic eight-channel pixel combiner circuit designed to readout superconducting nanowire single photon detectors (SNSPDs) is presented. The circuit is designed to amplify, digitize, edge detect, and combine the output signals of an array of eight SNSPDs. The design has been enabled by the development of novel large-signal cryogenic HBT simulation models. The circuit has been fabricated and measurement results demonstrate excellent agreement with simulation.