Subranging Superconductor ADC

Using magnetic flux quantum as a unit of conversion, and coupled with on-chip ultrafast rapid single flux quantum digital circuits, cryogenic superconductor analog-to-digital converter (ADC) technology offers discriminating performance advantages over competing technologies in sensitivity, linearity, and sampling rate. Extension of the single modulator design with an innovative subranging architecture has a potential performance leap (>30dB) in signal-to-noise ratio and spur-free-dynamic range that will exceed the stated requirements. The subranging ADC concatenates the ranges of a coarse and a fine ADC through an inter-range interface, which presents implementation challenges due to its inherent complexity. Recent advances in mixed-signal design concepts for the inter-range interface, propelled by the imminent transition to the faster and denser next generation Josephson junction circuit fabrication, now enable realization of the proposed subranging architecture. In Phase I, we will not only design the inter-range interface circuitry but also investigate two new ADCs to reduce the interface complexity. The first realization of the subranging ADC in Phase II will be followed by construction and delivery of complete receivers in Phase III. Recently, we have made significant advances in demonstrating and delivering complete receiver systems by combining superconductor chips with other cooled and un-cooled electronics to Navy laboratories.