标题： 交流偏置移位寄存器沟槽中通量捕获影响的提取与仿真 显示英文标题

标题： Extraction and Simulation of the Impact of Flux Trapping in Moats of AC-Biased Shift Registers

摘要： 超导接地平面中的沟槽用于将磁通量从超导集成电路的敏感部分隔离出来。 我们模拟了在沟槽中捕获的磁通量对交流偏置的SFQ移位寄存器（ShReg）的操作裕度的影响，考虑了各种相容的沟槽几何形状、沟槽尺寸、在ShReg单元中的位置、捕获的通量子的数量和极性。 使用电感提取器InductEx，我们提取了沟槽与ShReg电感之间的互耦合，并将其包含在优化后的网表中。 然后，我们使用JoSim模拟电路操作，并找到使寄存器开始正确操作的交流时钟幅度阈值。 该阈值的相对变化用于表征磁通捕获对电路操作的影响。 蒙特卡罗模拟用于研究电路参数变化对阈值统计特性的影响，使用从制造工艺控制监控中提取的约瑟夫森结临界电流和电路电感的标准偏差。 获得的分布与独立测量的具有108,500个约瑟夫森结的交流偏置移位寄存器各单元的阈值幅度分布进行比较。 结果表明，设计合理的沟槽中的磁通捕获对大规模移位寄存器的操作裕度影响非常小，而阈值的单元间变化主要来自结的临界电流的变化。 显示英文摘要

摘要： Moats in superconducting ground planes are used to trap magnetic flux away from sensitive parts of superconductor integrated circuits. We simulate the effect of magnetic flux trapped in moats on the operating margins of ac-biased SFQ shift registers (ShReg) with two ground planes for various congruent moat geometries, moat sizes, locations in the ShReg cells, number and polarity of the trapped of fluxons. Using inductance extractor InductEx, we extract mutual couplings between the moats and the ShReg inductors and include them in the refined netlist. Then, we use JoSim to simulate the circuit operation and find the threshold ac clock amplitude above which the register starts to operate correctly. The relative change in this threshold is used to characterize the influence of flux trapping on the circuit operation. Monte-Carlo simulations are used to investigate the effect of the circuit parameter variations on the statistics of the threshold, using the standard deviation of the Josephson junction critical current and of the circuit inductance extracted from the fabrication process control monitors. The obtained distributions are compared with the independently measured distributions of the threshold amplitude for the individual cells of ac-biased shift registers with 108,500 Josephson junctions. The results show that flux trapping in properly designed moats have a very small effect on the operation margins of the large-scale shift registers whereas the main contribution to the cell-to-cell variation of the threshold comes from the variation of the junctions' critical currents.