Switching delay of a nonlatching Josephson gate evaluated from ring oscillator operation

The authors present the experimental results for the switching delay of a dc-biased nonlatching Josephson gate (a coupled-superconducting quantum interference device gate). The measurement is executed by the use of a ring oscillator (RO) method. A frequency-to-voltage converter is used to evaluate the oscillation frequency of the RO. The circuit is designed and fabricated using a 2.5-kA/cm/sup 2/ Nb/AlO/sub x//Nb Josephson junction technology. The results show the minimum switching delay of 18 ps.