Time-to-digital converters based on RSFQ digital counters

A time-to-digital converter was designed, fabricated and tested. The converter circuit features superconductive counters based on toggle flip-flops with destructive readout, pulse detectors, parallel-to-serial converters and shift registers. HYPRES' library of standard RSFQ cells was used for the implementation of the circuits in HYPRES' standard Nb process with a 1.0 kA/cm2 critical current density.