Noise temperature and linewidth of high-temperature-superconducting heterodyne gigahertz oscillators

A method for the generation of stable, widely tunable heterodyne oscillations by means of a high-temperature-superconducting resistive superconducting quantum interference device is described. The details of the fabrication techniques, electrical characteristics, operating temperatures and frequency range of 100MHz–2GHz, are reported. The noise temperatures of several devices, made and tested in different laboratories, are estimated and the linewidths of the heterodyne oscillations are compared with theoretical values.