One embodiment describes a Josephson current source system. The system includes a flux-shuttle loop that is inductively coupled with an AC input signal. The flux-shuttle loop includes a plurality of Josephson junctions spaced about the flux-shuttle loop and being configured, when activated, to sequentially trigger the plurality of Josephson junctions about the flux-shuttle loop in response to the AC input signal to generate a DC output current provided through an output inductor. The system also includes a flux injector that is configured to selectively activate and deactivate the flux-shuttle loop in response to an input signal to control an amplitude of the DC output current.