1 volt DC programmable Josephson voltage standard

NIST has developed a programmable Josephson voltage standard (JVS) that pro duces intrinsically stable voltages that are programmable from -1.1 V to +1 .1 V. The rapid settling time (1 mu s), large operating current margins (2 to 4 mA), and inherent step stability of this new system make it superior t o a conventional JVS for many de measurements. This improved performance is made possible by a new integrated-circuit technology using intrinsically s hunted superconductor-normal-superconductor (SNS) Josephson junctions. Thes e junctions operate at lower excitation frequencies (10 to 20 GHz) than a c onventional JVS and have 100 times greater noise immunity. The Josephson ch ip consists of a binary array sequence of 32 768 SNS Josephson junctions. T he chip has been integrated into a completely automated system that is find ing application in mechanical / electrical watt-balance experiments, evalua tion of thermal voltage converters, electron-counting capacitance standards , and metrology triangle experiments.