Wide margin voltage locked array of Josephson junctions and its use as amplifier

The use of unshunted junctions to close the superconducting loop of two shunted junctions in series is shown to improve the voltage locking range compared to the more common use of passive elements such as resistors or capacitors. Stacking pairs of junctions in a ladder-like form with one junction common for each two steps makes it possible to phase lock more than two junctions. Simulations show that four junctions with 5% matching can be locked from 0 to 55μV. The device can also be used as a voltage amplifier by driving one of the junctions. Simulations show that an array of four series junctions operates as an amplifier between 12μV to 33μV input. Input impendance was 6 ohms and output impedance was 12 ohms.