SERIES JOSEPHSON-JUNCTION ARRAYS AS A HIGH-OUTPUT VOLTAGE-AMPLIFIER

We are investigating the potential of series arrays of nonhysteretic Josephson Junctions as high output voltage amplifiers. Such amplifiers may be useful in Josephson Junction-to-CMOS drivers in Superconductor/Semiconductor hybrid systems. The I-V curves of these arrays are sensitive to the nature and degree of coupling between the junctions in the array. The coupling is determined by the type and the value of the load as well as the junction capacitance (i.e. beta(c)). Depending on the nature of the load, the junctions may lock in phase (''in-phase state'') or couple such that the fundamental of the Josephson oscillations cancel (''anti-phase state''), suppressing the high frequency Josephson oscillations in the load. Using numerical simulations, we studied the stability of such states to various loads of interest and under static and dynamic drive conditions.