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Accurate experimental and theoretical comparisons between superconductor-insulator-superconductor mixers showing weak and strong quantum effectsA systematic study of the gain and noise in superconductor-insulator-superconductor mixers employing Ta based, Nb based, and Pb-alloy based tunnel junctions was made. These junctions displayed both weak and strong quantum effects at a signal frequency of 33 GHz. The effects of energy gap sharpness and subgap current were investigated and are quantitatively related to mixer performance. Detailed comparisons are made of the mixing results with the predictions of a three-port model approximation to the Tucker theory. Mixer performance was measured with a novel test apparatus which is accurate enough to allow for the first quantitative tests of theoretical noise predictions. It is found that the three-port model of the Tucker theory underestimates the mixer noise temperature by a factor of about 2 for all of the mixers. In addition, predicted values of available mixer gain are in reasonable agreement with experiment when quantum effects are weak. However, as quantum effects become strong, the predicted available gain diverges to infinity, which is in sharp contrast to the experimental results. Predictions of coupled gain do not always show such divergences.
Document ID
19880051425
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Mcgrath, W. R.
(California Institute of Technology, Jet Propulsion Laboratory, Pasadena; California, University Berkeley, United States)
Richards, P. L.
(California, University Berkeley, United States)
Face, D. W.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Prober, D. E.
(Yale University New Haven, CT, United States)
Lloyd, F. L.
(NBS Boulder, CO, United States)
Date Acquired
August 13, 2013
Publication Date
April 15, 1988
Publication Information
Publication: Journal of Applied Physics
Volume: 63
ISSN: 0021-8979
Subject Category
Electronics And Electrical Engineering
Accession Number
88A38652
Funding Number(s)
CONTRACT_GRANT: NSF ECS-86-04350
CONTRACT_GRANT: AF-AFOSR-85-0230
CONTRACT_GRANT: N00014-80-C-0855
CONTRACT_GRANT: NSF ECS-83-05000
CONTRACT_GRANT: N00014-85-C-0233
Distribution Limits
Public
Copyright
Other

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