EXPERIMENTAL INVESTIGATION OF A HIGH-FREQUENCY SAMPLING SYSTEM BASED ON SHUNTED JOSEPHSON-JUNCTIONS

We propose a new type of sampler design based on shunted junctions (beta(c) = 1). The sampler is to be used for the investigation of single flux quantum devices (RSFQ) employing similar junctions (Kaplunenko et al 1989, Filippenko et al 1991). We measure the time resolution of the sampler and delay time of the shunted Josephson junction array. The circuit was manufactured on a single chip and was DC powered. We employed Nb-AlOx-Nb tunnel junctions of 300 A m-2 critical current density and observed Josephson oscillations of the output junction at frequencies from 6 to 50 GHz. Despite a long plasma period of 20 ps the time resolution was 5 ps. The transmission line of 27 Josephson junctions (critical current 165-mu-A each) demonstrated time delay of 0.5 ps mu-A-1.