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Title: Switching speed of DCL-gates with high-J /SUB c/ Josephson junctions

Abstract

Switching speed and bias current margin of DCL-gates composed of high-J /SUB c/ junctions are investigated by both numerical calculation and experimental measurement. It is shown that switching speed is improved by increasing J /SUB c/ . However, the switching speed and bias current margin of DCL-gates are restricted by the increase in the minimum resetting current for the high-J /SUB c/ junction. The theoretical J /SUB c/ limit for a Nb oxide barrier junction is found to be about 7 X 10/sup 8/ A/m/sup 2/ from numerical results, and the J /SUB c/ values that produce bias current margins of greater than 20 % are found by both numerical and experimental results to be less than 2 about 3 X 10/sup 8/ A/m/sup 2/. The switching delay obtained experimentally for a DCL-gate with a J /SUB c/ value of 2 X 10/sup 8/ A/m/sup 2/ is 5.6 ps, which is in good agreement with the numerical result.

Authors:
; ; ;
Publication Date:
Research Org.:
Central Research Laboratory, Hitachi, Ltd., Kokubunji 185, Tokyo
OSTI Identifier:
6485609
Report Number(s):
CONF-840937-
Journal ID: CODEN: IEMGA
Resource Type:
Conference
Resource Relation:
Journal Name: IEEE Trans. Magn.; (United States); Journal Volume: MAG-21:2; Conference: Applied superconductivity conference, San Diego, CA, USA, 9 Sep 1984
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; GATING CIRCUITS; PERFORMANCE; TIMING PROPERTIES; LOGIC CIRCUITS; JOSEPHSON JUNCTIONS; SWITCHING CIRCUITS; ELECTRONIC CIRCUITS; JUNCTIONS; SUPERCONDUCTING JUNCTIONS 420201* -- Engineering-- Cryogenic Equipment & Devices

Citation Formats

Nishino, T., Hatano, Y., Kawabe, U., and Tarutani, Y.. Switching speed of DCL-gates with high-J /SUB c/ Josephson junctions. United States: N. p., 1985. Web.
Nishino, T., Hatano, Y., Kawabe, U., & Tarutani, Y.. Switching speed of DCL-gates with high-J /SUB c/ Josephson junctions. United States.
Nishino, T., Hatano, Y., Kawabe, U., and Tarutani, Y.. 1985. "Switching speed of DCL-gates with high-J /SUB c/ Josephson junctions". United States. doi:.
@article{osti_6485609,
title = {Switching speed of DCL-gates with high-J /SUB c/ Josephson junctions},
author = {Nishino, T. and Hatano, Y. and Kawabe, U. and Tarutani, Y.},
abstractNote = {Switching speed and bias current margin of DCL-gates composed of high-J /SUB c/ junctions are investigated by both numerical calculation and experimental measurement. It is shown that switching speed is improved by increasing J /SUB c/ . However, the switching speed and bias current margin of DCL-gates are restricted by the increase in the minimum resetting current for the high-J /SUB c/ junction. The theoretical J /SUB c/ limit for a Nb oxide barrier junction is found to be about 7 X 10/sup 8/ A/m/sup 2/ from numerical results, and the J /SUB c/ values that produce bias current margins of greater than 20 % are found by both numerical and experimental results to be less than 2 about 3 X 10/sup 8/ A/m/sup 2/. The switching delay obtained experimentally for a DCL-gate with a J /SUB c/ value of 2 X 10/sup 8/ A/m/sup 2/ is 5.6 ps, which is in good agreement with the numerical result.},
doi = {},
journal = {IEEE Trans. Magn.; (United States)},
number = ,
volume = MAG-21:2,
place = {United States},
year = 1985,
month = 3
}

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  • The use of Josephson devices as switching components for computer circuits was investigated including a study of the switching properties of the superconductor-semiconductor-superconductor junction. The switching speeds of a single junction and a basic memory cell computed by numerical methods are comparable with the corresponding values for oxide-barrier junctions. Having a much lower Q than the conventional oxide-barrier junction, the junction should not show the previously experienced difficulties caused by junction resonances. The damping of plasma oscillations in the semiconductor junction is also more effective, leading to a shorter switching time. A new type of logic gate employing Josephson devicesmore » was investigated. This circuit would automatically unlatch after each operation, thus requiring no external means for resetting. Numerical analysis predicts subnanosecond switch-reset operation for appropriate parameter choices. The qualitative behavior of the circuit was also shown with a mechanical analog. (auth)« less
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  • A single Josephson tunnel junction rapidly switches from zero voltage to the gas voltage of a few millivolts when the current bias exceeds the critical current. This paper describes a circuit which allows at least 400 junctions connected in series to be synchronously switched. Instead of a few millivolts for a single junction, an array of 400 junctions switches directly to one volt. The junctions, integrated into a stripline circuit similar to that described for series array voltage standards, are commonly biased by a dc current source. When the dc bias is increased the junction with the smallest critical currentmore » first switches to the normal state. This causes a pulse to propagate along normal state. The maximum number of junctions to be switched is proportional to the average critical current of the circuit. The switching time is mainly determined by the signal speed of the pulse in the stripline.« less