Direct measurements of propagation delay of single-flux-quantum circuits by time-to-digital converters

Abstract

Direct measurements of propagation delay of single-fluxquantum (SFQ) circuits were performed using SFQ double-oscillator time-to-digital converters. The propagation delay of several SFQ logic gates in our cell library named CONNECT were measured in picosecond resolution. Small discrepancy in the propagation delay of picosecond level was observed between measurement and circuit simulation results. The discrepancy is well explained assuming the parasitic inductance around shunt resistors of Josephson junctions. Keywords: SFQ circuits, superconducting devices, TDC, Josephson junctions, superconducting integrated circuits, propagation delay Classification: Superconductivity References

Impedance Matching of Microstrip Inductors in Digital Superconductive Electronics

“…The obtained reduction of jitter is in the range of 20 % and can also be observed in circuit simulation for larger values of the junction capacitance. The timing parameters of a JTL depend much more significant on the loop inductance and recent measurements on the switching delay confirmed also the influence of the parasitic inductance [11]. To analyse the small storing loop, we estimated all capacitances to ground for an existing layout of a delay-flip-flop (DFF) and included microstrip line models into our circuit simulation.…”