Low-Noise Superconducting Mixers for the Terahertz Frequency Range
Victor Y. Belitsky, Serguei Cherednichenko, Dag Winkler
This chapter discusses the high sensitivity superconducting mixers, i.e. detectors used in heterodyne receivers. Today, there are essentially two very successful concepts of superconducting mixers, or frequency down-converters, the superconductor-insulator-superconductor tunnel junction SIS mixer and the superconducting hot-electron bolometer mixer. Moving up to higher frequencies in the microwave and millimeter wave electromagnetic spectra makes it more and more difficult to retrieve a good signal-to-noise ratio with ordinary solid-state amplifiers. The driving force for using superconducting mixers is their excellent down-conversion efficiency and capability to down-convert RF signals from microwave frequencies up to the terahertz region. The main purpose of a receiver is to pick up and amplify a weak signal, which can then be accurately determined in amplitude and phase. The mixer noise temperature and conversion gain are the most important parameters for the mixing device. The Josephson junction mixer was one of the first suggested devices based on superconducting point contacts and later tunnel junctions.
CRC Press eBooks•May 17, 2022•1 citation