A SUPERCONDUCTING MONOLITHIC FLASH A/D CONVERTER

HYPRES PROPOSES TO DEVELOP A HIGH-SPEED FLASH ANALOG-TO-DIGITAL CONVERTER IN LOW TC SUPERCONDUCTOR TECHNOLOGY (NIOBIUM). CIRCUIT SIMULATIONS HAVE SHOWN THAT THE PROPOSED CIRCUIT IS CAPABLE OF DIGITIZING INPUT BANDWIDTHS UP TO 10 GHZ WITH 4-BITS OF ACCURACY OF HIGHER RESOLUTION AT LOWER BANDWIDTHS (SEE ATTACHED PAPER BY HERBERT KO, 1988 APPLIED SUPERCONDUCTIVITY CONFERENCE PROCEEDINGS, P.826). IN PHASE I WE INTEND TO DEMONSTRATE THE FEASIBILITY OF OUR APPROACH AND TEST INDIVIDUAL COMPARATORS ALREADY FABRICATED BY HYPRES ON AN INTERNALLY FUNDED PROCESS RUN. WE ALSO INTEND TO SIMULATE AND LAY OUT THE NEXT GENERATION OF CIRCUITS FOR DC AND HIGH - SPEED TESTING OF FULL A/D CONVERTERS. LOOKING AHEAD, THIS PARTICULAR CIRCUIT IS EXPECTED TO BE THE MOST AMENABLE TO IMPLEMENTATION IN NBN TECHNOLOGY SINCE THE CIRCUIT IS EXTREMELY FORGIVING OF PROCESS VARIATION AND WOULD TOLERATE MUCH GREATER DEVIATIONS IN JUNCTION CRITICAL CURRENTS FROM NOMINAL VALUES THAN ANY OTHER SUPERCONDUCTIVE DESIGN. THIS SHOULD ENSURE A HIGH CIRCUIT YIELD FOR THIS A/D DESIGN. IN PHASE II, A COMPLETE FLASH A/D SYSTEM WITH DATA REGISTER,CONTROL GATES AND OUTPUT DRIVERS TO INTERFACE WITH ROOM TEMPERATURE ECL SEMICONDUCTOR CIRCUITRY, VME BUS COMPATIBLE WOULD BE DESIGNED, FABRICATED, TESTED AND CHARACTERIZED.