AN ANALOG TO DIGITAL CONVERTER WITH VERY HIGH SPEED, BASED ON SUPERCONDUCTING

THIS PROJECT AIMS TO DEVELOP A HIGH SPEED FLASH ANALOG-TO-DIGITAL CONVERTER (ADC) IN LOW CRITICAL TEMPERATURE SUPERCONDUCTOR TECHNOLOGY (NIOBIUM). CIRCUIT SIMULATIONS HAVE SHOWN THAT THE PLANNED CIRCUIT IS CAPABLE OF DIGITIZING INPUT BANDWIDTHS UP TO 10 GHZ WITH 6 BITS OF ACCURACY OR HIGHER RESOLUTION AT LOWER BANDWIDTHS. THE SLOWSPEED OPERATION OF A 4-BIT FLASH HAS ALREADY BEEN DEMONSTRATED, AND THE DYNAMIC RANGE REQUIRED FOR 8-BIT OPERATION HAS BEEN SHOWN. FURTHERMORE, INDIVIDUAL COMPARATORS WERE TESTED AT 2 GHZ, 5 GHZ, AND 10 GHZ, AND PERFORMANCE UP TO THE LIMITS OF THESE TYPES OF TEST EQUIPMENT WAS DEMONSTRATED. PHASE I, INCLUDES THE DESIGN, FABRICATION, AND TESTING OF INDIVIDUAL COMPARATORS AND A COMPLETE 4-BIT FLASH USING FULL BANDWIDTH INPUT SIGNALS (1 TO 5 GHZ). THE PHASE I GOAL IS TO DEMONSTRATE THE SUBPICOSECOND APERTURE UNCERTAINTY OF THE FLASH DESIGN AND HENCE THE ABILITY TO DIGITIZE VERY HIGH BANDWIDTH SIGNALS. THE FLASH ADC CIRCUIT IS EXPECTED TO BE THE MOST AMENABLE TOIMPLEMENTATION IN NIOBIUM NITRIDE TECHNOLOGY BECAUSE THE CIRCUIT IS EXTREMELY FORGIVING OF PROCESS VARIATION AND TOLERATES MUCH GREATER DEVIATION FROM NOMINAL VALUES IN JUNCTION CRITICAL CURRENTS THAN ANY OTHER SUPERCONDUCTIVE DESIGN. THIS FACT SHOULD ENSURE A HIGH CIRCUIT YIELD FOR THIS ADC DESIGN.