Conversion gain and noise in a Josephson effect mixer

Y. Taur, J. H. Claassen, P. L. Richards

The measured performance of Nb–Nb point contact Josephson junctions used as 36-GHz microwave mixers is in good agreement with the predictions of the resistively shunted junction model. Conversion efficiencies greater than unity are attained, with mixer noise temperatures comparable with the best competing devices.

B. T. Ulrich, T. Lee

F. Ya. Nad

Yuan Taur, J. H. Claassen, P. L. Richards

The measured performance of Nb-Nb point contact Josephson-junctions used as 36 GHz microwave mixers is in good agreement with the predictions of the resistively shunted junction model. Conversion efficiencies greater than one are attained, with mixer noise temperatures comparable with the best competing devices.

J. H. Claassen, Y. Taur, P. L. Richards

We have recently shown that point contact Josephson junctions can function as millimeter wave heterodyne mixers with conversion gain. The best results achieved thus far show a single sideband conversion gain of 1.3 and a mixer contribution to the system noise temperature of 54K. Both of these results are ∼ 5 times better than the best published figures for cooled Schottky barrier diode mixers operated at the same frequency. The measured noise for a variety of junctions can be expressed as a universal function of the normalized rf frequency \Omega = \hbar \omega/2eI_{c}R . It is about a factor 2 larger than the calculated noise arising from the thermal noise in the junction shunt resistance R. The noise calculation was done for the resistively shunted junction model using an analog junction simulator.

Flavius Schackert, Baleegh Abdo, Michael Hatridge +3 more