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The charge pump phase-locked loops with a digital sequential phase frequency detector are analyzed using linear and nonlinear models. Nonlinear analytical maps are derived. The stability analysis results agree with linear analysis results, with higher order corrections. The effects of the ioop delay are also discussed. [ABSTRACT FROM AUTHOR]

Current-driven dynamics of superconducting phases of Josephson junction networks in magnetic fields are studied numerically. We here consider two-dimensional arrays (Josephson junction arrays, JJAs) with positional disorder. In the presence of strong disorder and driving bias currents, the nucleation of vortex–antivortex pairs causes the plastic flow and elastic flow of phases in JJAs. We focus on two threshold currents that characterize the boundaries of these flow regimes. We analyze the threshold currents on the basis of the scaling theory of pinning due to random potentials. It is found that the threshold currents show scaling behaviors characterized by scaling exponents in one dimension. [Copyright &y& Elsevier]