A four ihput-and-gate with five asymmetric interferometers

Abstract

The static and dynamic behavior of a four input-AHD-gate for a parallel fan out of three has heen simulated. Only asymmetric interferometers with two unequal Josephson junctions as input devices are used instead of interferometers with three junctions in order to save circuit area and to improve performance. The input devices have a characteristic phase X = 2.1 and a ratio of the maximum Josephson-currents of 3:1. The AND-function of each pair of inputs is performed in a similar manner as described by Klein and Herrell. The AND-function of the two input pairs is realized with a nonlinear injection gate. The number of interferometers used in this AND-gate is reduced by two compared with known proposals. With tolerances of the maximum Josephson currents of ± 10 % and additional tolerances of ± 9 % of the input and supply currents the worst case and average nominal logic delays are about 170 ps and 60 ps. © 1981 IEEE