FD-TLM Simulation of Josephson Junction Logic Circuits.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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Josephson junction integrated circuits are capable of operating at clock frequencies from 1 to 100 GHz. At these frequencies, analysis of signal propagation delay, crosstalk, dispersions, radiation, and reflections must be included to determine proper response of the circuit. Much effort is required in simulating high frequency behavior, where the cross sectional dimensions of conductors are comparable to the signal wavelength, with conventional circuit simulation methods as SPICE. A simulation method capable of modeling high frequency behavior by solving Maxwells curl equations, the finite difference transmission line matrix method FD-TLM, is modified to model JJ logic circuits and provide simultaneous time domain three dimensional full wave electromagnetic field and JJ device analysis. The FD-TLM method is further extended to model superconducting quantum interference devices SQUIDs. Techniques for simulation and simulation results for a Josephson Atto-Weber switch JAWS, a two-junction superconducting quantum interference device SQUID, and a modified variable threshold logic MvTL gate are provided. Interconnection lengths are kept intentionally short so the FD-TLM simulations can be validated by conventional, low frequency, quasi-static analysis. The general behavior observed in FD-TLM simulation and good agreement with quasistatic conventional circuit simulation validate the FD-TLM method.
- Electricity and Magnetism
- Electrical and Electronic Equipment