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Applied Superconductivity, IEEE Transactions on

Issue 4 • Date Dec. 1991

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Displaying Results 1 - 7 of 7
  • Josephson-Junction driven submillimeter wave microstrip resonator

    Page(s): 145 - 149
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (423 KB)  

    A microstrip resonator driven by a resistively shunted Josephson junction has been used for submillimeter-wave surface resistance measurements to about 400 GHz. A simple, analytical analysis of the resonator-induced structure in the junction's I-V characteristic gives the resonator surface resistance in the range of 2-160 m Omega with an accuracy of better than 30%.<> View full abstract»

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  • Modeling of a quasi-optical Josephson oscillator

    Page(s): 150 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (601 KB)  

    The authors have developed a computer model of a Josephson tunnel junction embedded in a general circuit with frequency-dependent impedance using the harmonic balance method. This model has been applied to the analysis of a two-dimensional Josephson junction array with integrated coupling structures, called a quasi-optical Josephson oscillator. Simulations are done for a junction with dipole, slotline, and bow-tie antennas. The results show that the junction with a bow-tie antenna gives the best performance, and the output power from an array of 4000 junctions can reach 25.7 mu W at a frequency as high as 1091 GHz for niobium junctions deposited on a 0.207-mm-thick quartz substrate.<> View full abstract»

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  • Margins and yield in single flux quantum logic

    Page(s): 157 - 163
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    Simulations are used to optimize the design of simple rapid single flux quantum (RSFQ) logic gates and to determine their margins. Optimizations based on maximizing the smallest (critical) margin result in critical margins in the range of 19-50%. A Monte Carlo approach is used to illustrate the relationship between margins and process yield. Based on single gate simulations, the results show that 1 sigma parameter spreads of less than about +or-5% will be required to make medium- or large-scale integrated RSFQ logic circuits. A single-bit full adder using five RSFQ gates and a local self-timing network are simulated with discrete components. The full adder used 2000-A/cm/sup 2/ junctions with a specific capacitance of 0.04 pF/ mu /sup 2/ and had a logic delay of 87 ps and a worst-case margin of +or-19%. A small margin reduction which is not present in the individual gate simulations results from loading.<> View full abstract»

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  • A subnanosecond clock cryogenic system for Josephson computers

    Page(s): 164 - 169
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (545 KB)  

    Using Josephson chips maintained at 4.4 K by a closed-cycle 3-W desk-size refrigerator, the authors verified the correct operation of a 4-b Josephson microprocessor up to 1.1 GHz. Room temperature and liquid He temperature regions are connected with a 130-ps delay using I/O cables passing through sidewalls of a vacuum vessel. It is proposed that both semiconductor and Josephson devices can coexist on circuit boards that constitute the equivalent of a single board.<> View full abstract»

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  • Analysis of the threshold characteristics of the uniform Josephson flux shuttle

    Page(s): 170 - 174
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    A general method for calculating the mode boundaries of a uniform flux shuttle and numerical techniques for computing these thresholds are presented. A number of examples of practical interest are given, including the current distribution in a shuttle due to a single vortex, and static margins of directly injected two-phase shift registers and magnetically clocked three-phase shift registers. Comparison with dynamic circuit simulations shows that the static thresholds are good approximations over a wide range of junction parameters.<> View full abstract»

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  • DC transport measurements at 77 K of high J/sub c/ cryostabilized melt processed YBCO monofilament

    Page(s): 175 - 178
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    DC transport critical current density measurements, with J/sub c/ values up to 1.4*10/sup 5/ A/cm/sup 2/ in zero field and 4.4*10/sup 4/ A/cm/sup 2/ in 1 T, performed in liquid nitrogen on melt-processed YBCO fiber from 0 to 1 T, are reported. The measurement technique is described, and the effects of contact heating and cryostabilization are discussed.<> View full abstract»

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  • Coaxial line configuration for microwave power transmission study of YBa/sub 2/Cu/sub 3/O/sub 7- delta / thin films

    Page(s): 178 - 180
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (271 KB)  

    Microwave transmission measurements through YBa/sub 2/Cu/sub 3/O/sub 7- delta / (YBCO) high-transition-temperature superconducting thin films on lanthanum aluminate (LaAlO/sub 3/) have been performed in a coaxial line at 10 GHz. LaAlO/sub 3/ substrates were ultrasonically machined into washer-shaped discs, polished, and coated with laser-ablated YBCO. These samples were mounted in a 50- Omega coaxial air line to form a short circuit. The power transmitted through the films as a function of temperature was used to calculate the normal state conductivity and the magnetic penetration depth for the films.<> View full abstract»

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Aims & Scope

IEEE Transactions on Applied Superconductivity contains articles on the applications of superconductivity and other relevant technology.

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Meet Our Editors

Editor-in-Chief
Britton L. T. Plourde
Syracuse University
bplourde@syr.edu
http://www.phy.syr.edu/~bplourde