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Current Steering Logic with Two Phase Reset

IP.com Disclosure Number: IPCOM000085724D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Schuenemann, C.: AUTHOR

Abstract

Logic circuits with Josephson junctions can be designed using the concept of steering a current from one path to another. For resetting the logic circuits, current has to be retransferred into the original path. Erroneous hanging up of Josephson junctions in their voltage states could possibly occur if logic control input signals A ... E have not properly been removed before the reset operation starts with the application of a reset pulse R to the respective junction in the second path. To overcome that problem a forced commutation is now achieved by providing an additional Josephson junction T bridging the logic junctions within the first path.

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Current Steering Logic with Two Phase Reset

Logic circuits with Josephson junctions can be designed using the concept of steering a current from one path to another. For resetting the logic circuits, current has to be retransferred into the original path. Erroneous hanging up of Josephson junctions in their voltage states could possibly occur if logic control input signals A ... E have not properly been removed before the reset operation starts with the application of a reset pulse R to the respective junction in the second path. To overcome that problem a forced commutation is now achieved by providing an additional Josephson junction T bridging the logic junctions within the first path.

At the end of a clock cycle, e.g., defined by clock pulses C1, C2, the control current of junction T is first removed by a negative pulse so that junction T transiently assumes the superconducting state. Now it can draw current. In a second phase the reset pulse is applied to reset junction R, overlapping with negative pulse T. Consequently all current is being transferred to junction T. After termination of pulse T, junction T reswitches into the voltage state, and the loop current is taken over by the logic junctions to render them ready for the next cycle. Thus current is definitely transferred to the loop branch containing the logic junctions. Loop inductances L1, L2 have to be adjusted such that this current transfer occurs in the desired order.

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