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Current Injection Josephson Interferometer With Magnetic Input Signal Coupling

IP.com Disclosure Number: IPCOM000052778D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Bachtold, W: AUTHOR [+3]

Abstract

This article describes a Josephson interferometer employing direct signal injection and magnetic coupling, e.g., as negative feedback, of the input signals to the interferometer loop. This results in a steep slope threshold characteristic permitting high input signal tolerances and makes the interferometer particularly suited for logic circuitry. The concept demonstrated for the specific example of an asymmetric 2-junction interferometer is applicable to any multi-junction interferometer structure.

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Current Injection Josephson Interferometer With Magnetic Input Signal Coupling

This article describes a Josephson interferometer employing direct signal injection and magnetic coupling, e.g., as negative feedback, of the input signals to the interferometer loop. This results in a steep slope threshold characteristic permitting high input signal tolerances and makes the interferometer particularly suited for logic circuitry. The concept demonstrated for the specific example of an asymmetric 2-junction interferometer is applicable to any multi-junction interferometer structure.

Fig. 1 shows the equivalent circuit of a 2-junction interferometer with input signals I(A) and I(B) injected at points A and B, respectively. These input signals are also magnetically coupled to the interferometer loop: signal I(A) through windings L'(1)/L(1), and signal I(B) through windings L'(2)/L(2). The amount of coupling is determined by the division of the total inductance L into L(1), L(2) and L(3). Negative feedback is obtained by proper arrangement of the windings L'(1)/L(1) and L'(2)/L(2). The interferometer of Fig. 1 is asymmetric in that the maximum Josephson currents I(j) of the junctions differ: I(j1).aI(o), I(j2).bI(o).

Fig. 2 shows, for the parameter values indicated, the threshold characteristic of a 2-junction interferometer.

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