CURRENT INJECTION TYPE LOGICAL GATE CIRCUIT USING JOSEPHSON EFFECT

摘要

PURPOSE:To execute the titled circuit by a wide gate current margin by connecting in series two pieces of resistances, respectively, between plural pieces of pre-stage logical gate circuits and next stage logical gate circuits, and connecting a Josephson junction between the respective connecting points and a ground. CONSTITUTION:Current injection type gate circuits 30, 31 and 32 consist of the same circuit structure as a logical gate circuit shown by an equivalent circuit (figure a). Between connecting points 37, 38 of a resistance and a ground, Josephson 35, 36 are connected. When a current inputted from the connecting points 37, 38 is denoted as Iin, and 2I0/3, (r), and R'L denote a critical current value of a junction 10, a resistance value of a resistance 16, and a resistance value of resistances 33, 34, respectively, a critical current value I1 of the junctions 35, 36 is selected so as to satisfy an expression I. When the circuit 30 is switched, an output current Iin flows into the junction 35, but by a condition of the expression I, the junction 35 is switched, the current Iin is injected from a input terminal 19, and the circuit 32 is switched. In the course of this operation, the junction 36 is in a zero voltage state by the condition of the expression I, and no leak current flows into the circuit 31. Accordingly, a gate current value can be raised to a gate current threshold value 2I0 of the time when no input current is applied.