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Fast Two Stage Josephson Logic

IP.com Disclosure Number: IPCOM000085725D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Schuenemann, C: AUTHOR

Abstract

A Josephson technology logic block is made of a cascade unit combining an input state including several series connected Josephson logic gates with a complementary circuit output stage.

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Fast Two Stage Josephson Logic

A Josephson technology logic block is made of a cascade unit combining an input state including several series connected Josephson logic gates with a complementary circuit output stage.

Gate current I is supplied via a regulator (and inverter) Josephson junction R. Then it runs through several series connected Josephson junctions as logic gates having respective logic inputs A, B, C. The true output current I1 of the first stage is sent through both antiseries connected control lines of a self- resetting complementary circuit. The latter stage comprises two series connected Josephson junctions which are clamped to a voltage corresponding to the gap voltage. Therefore, only one out of both junctions can be in the voltage state at a time.

A bias applied to one of the junctions creates the necessary asymmetry to make the circuit self-resetting or it defines the operating point, respectively. Normally in the voltage state, an additional Josephson junction provides the supply of V-GAP. The true output current F of the second stage can be taken from the top between both junctions, or the complement output current F can be taken from the upper end of the not-grounded junction.

This basic block can be modified in different ways. The complementary output stage e.g., can be designed as a flip-flop circuit or latch. An appropriate external reset pulse then has to be applied to one of both junctions. Also more than one logic input stages operat...