A 100 GHz JOSEPHSON MIXER USING RESISTIVELY-SHUNTED Nb TUNNEL JUNCTIONS

We describe preliminary mixer results using resistively shunted Nb/AlOx/Nb tunnel junctions in a 100 GHz waveguide mixer mount. The mixer utilizes robust, lithographically-defined devices which have non-hysteretic I-V curves. We have obtained a receiver temperature of 390 K (DSB), with a conversion loss of -6.5 dB. The receiver's behavior agrees qualitatively with the behavior predicted by the resistively shunted junction (RSJ) model. Substantial improvements in performance are expected with the use of better optimized shunted junctions, and numerical simulations suggest that if devices with higher ICRN products can be obtained, Josephson effect mixers could be competitive with SIS mixers at high frequencies.