A new microwave circuit and a new cryoprobe for Josephson voltage standards

We present a new type of microwave circuits for Josephson voltage standards. Coplanar strips (CPS) are used instead of microstriplines or coplanar waveguides (CPW) to integrate the Josephson junctions in a microwave transmission line. Compared to microstripline and CPW circuits the CPS design doubles the scale of integration and simplifies the fabrication technology. Well-operating 10 V circuits in CPS design with 17,000 SIS junctions and 1 V SINIS circuits were tested in a new cryoprobe. In this cryoprobe a low loss dielectric waveguide consisting of a teflon strip is used for the microwave transmission in the 70 GHz frequency range. The dielectric waveguide together with a fibreglass-reinforced plastic supporting tube reduces the contribution of the cryoprobe to the liquid helium boil-off rate drastically. This paper was presented at the 8th International Superconductive Electronics Conference, Osaka, Japan, 19–22 June 2001.