Current amplifier and flux-buffer designs using an exponential flux shuttle with a Josephson junction synthetic inductor

A current amplifier design based on the principle of fluxon propagation in a multijunction exponential flux shuttle has been investigated. In this design, the critical current of the junctions is increased exponentially and the SQUID (superconducting quantum interference device) inductance is a Josephson-junction equivalent inductance. Current gain can be achieved by generating fluxons at the low end and dissipating them at the high end where the load is located. Advantages over other types of linear devices are discussed. Two parallel exponential flux shuttles can be used to duplicate flux from a high-inductance input coil to a low-inductance output. The device performance of the two circuits is evaluated by computer simulation, and noise performance is discussed