Noise temperature of a Josephson frequency down-converter in self-pumping operation

Operational characteristics of a low-noise receiver with a Josephson frequency down-converter operated in the self-pumping regime are described. The noise temperature and the response of the receiver were determined for the cases of a cold (80 K) and warm (300 K) matched load applied to the input. An expression for the noise temperature is included which can also be used for a qualitative description of the conversion in frequency converters of other types with a noisy reference voltage. Noise temperatures of less than 100 K were obtained for the point superconducting contacts with R = 100 Ohm.