Design of a turn-key 10 V Programmable Josephson Voltage Standard system

NIST is designing a 10 V Programmable Josephson Voltage Standard (PJVS) system with an improved microwave design and arrays of stacked Nb
_x
Si
_1-x
-barrier Josephson junctions. For this new design a "ground-up" approach was used that takes into account all system issues in order to produce a robust 10 V system. By improving the uniformity of the microwave drive along the length of each array, constant-voltage steps with a larger current range are generated allowing the use of smaller critical current junctions. Smaller critical currents are important for lowering the total overall power dissipated on chip. Reducing power dissipation also increases the operating margins. Thus, all aspects of the design are interrelated and important for an optimized system.