Noise of superconductor/normal metal/superconductor mixer based on low voltage negative differential resistance effect.

The conversion efficiency was calculated for some type of high-Tc supercond ucting junctions, which hale negative derivative on current-voltage charact eristics. This distinguishing feature can be explained by Andreev, reflecti ons in superconductor/normal metal boundaries. In this work it is analyzed a combination of the theoretical predictions of noise, based on noise corre lation matrix of the mixer model, and theory of Likharev-Semenov for the th ermal noise. The conversion gain is possible in SNS mixers in spite of nois e in negative derivative region.