We fabricated single flux quantum RS flip-flop circuits by using ramp-edge
Josephson junctions and tested their performance. The junctions were constr
ucted with two Y1Ba2Cu3O7-x (YBCO) electrodes and a barrier layer, As barri
er materials we used cobalt-doped YBCO, To insulate between YBCO layers we
used Sr2AlTaO6(SAT) thin films. We also fabricated RS flip-flop circuits by
using YBCO ground planes to reduce the inductance of YBCO film. The fabric
ated Josephson junctions showed typical RSJ-like current-voltage (I-V) char
acteristics above 50K. We could successfully demonstrate the correct operat
ion of the RS flip-flop circuits at the temperatures near 50K, We used a co
mputer controlled digital measurement set-up to test the circuits, The RS f
lip-flop circuit fabricated on a ground plane showed more definite set and
reset states on the voltage-flux(V-phi) modulation corves of the read SQUID
than those of the circuit made without ground plane, This may be attribute
d to the shielding effect by a YBCO ground plane.