Measurement and Data-Assisted Simulation of Bit Error Rate in RQL Circuits

  1. Quentin Herr,
  2. Alex Braun,
  3. Andrew Brownfield,
  4. Ed Rudman,
  5. Dan Dosch,
  6. Trent Josephsen,
  7. and Anna Herr
A circuit-simulation-based method is used to determine the thermally-induced bit error rate of superconducting logic circuits. Simulations are used to evaluate the multidimensional
Gaussian integral across noise current sources attached to the active devices. The method is data-assisted and has predictive power. Measurement determines the value of a single parameter, effective noise bandwidth, for each error mechanism. The errors in the distributed networks of comparator-free RQL logic nucleate across multiple Josephson junctions, so the effective critical current is about three times that of the individual devices. The effective noise bandwidth is only 6-23% of the junction plasma frequency at a modest clock rate of 3.4GHz, which is 1% of the plasma frequency. This analysis shows the ways measured bit error rate comes out so much lower than simplistic estimates based on isolated devices.