Memory effect in balanced Josephson comparators

• Balanced Josephson comparator decisions depend on previous decisions at high frequencies.
• The maximum effective data rate is lower than the clock frequency.
• Tradeoff between maximum effective data rate and minimum comparator gray-zone.

The performance of a balanced Josephson comparator is measured by its gray-zone and its maximum operation frequency. A typical effect at high clock frequencies is the correlation of output bits with their predecessors, the comparator develops a memory. This is undesirable, as it imposes an upper limit on the useful clock frequency at which the comparator can be operated.In this work, we describe and observe experimentally the memory effect of a Josephson comparator and study its influence on the gray zone width and the maximum effective data rate.