Title :
Optimized 1 V and 10 V Josephson series arrays
Author :
Muller, Franz ; Pöpel, Ralf ; Kohlmann, Johannes ; Niemeyer, J. ; Meier, W. ; Weimann, T. ; Grimm, Lambert ; Dünschede, Friedrich-Wilhelm ; Gutmann, Peter
Author_Institution :
Phys. Tech. Bundesanstalt, Braunschweig, Germany
fDate :
4/1/1997 12:00:00 AM
Abstract :
Using a modified fabrication method and a detailed design investigation we have been able to optimize the array circuits for the Josephson voltage standard and to solve the trapped flux problem. Even in very long arrays (4800 junctions in a single stripline) a yield of 1 mV per junction could be achieved. The microwave power in the range from 70 GHz to 73 GHz required for stable operation of 1 V and 10 V circuits could be reduced to approximately 1 mW and 10 mW (antenna input), respectively. The best results at 10 V were obtained with circuits of 13 924 junctions arranged in 4 microwave paths connected in parallel. Excellent calibration conditions were maintained for current densities of about 10 A/cm2 for which the ratio of operating frequency to plasma frequency is increased to six
Keywords :
circuit optimisation; measurement standards; millimetre wave circuits; strip lines; superconducting microwave devices; superconductor-insulator-superconductor devices; voltage measurement; 1 V; 1 V circuits; 1 mW; 10 V; 10 V circuits; 10 mW; 70 to 73 GHz; Josephson voltage standard; Nb-Al2O3-Nb; Nb/Al2O3/Nb trilayer technique; array circuit optimization; calibration conditions; current densities; design investigation; fabrication method; microwave paths; microwave power; operating frequency to plasma frequency ratio; single stripline; stable operation; trapped flux problem; very long arrays; yield; Calibration; Current density; Design optimization; Fabrication; Frequency; Microwave antennas; Microwave circuits; Plasma density; Stripline; Voltage;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
