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Browse Prior Art Database

Low Temperature SLAVE Circuit

IP.com Disclosure Number: IPCOM000044524D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Heidel, DF: AUTHOR

Abstract

A SLAVE circuit in the Josephson latch is used to detect if current is stored in a superconducting storage loop during the transition time of the AC power supply. Previous SLAVE circuits used a single junction to sense the stored current; this design has poor operating margins and is relatively slow. This SLAVE circuit, shown in Fig. 1, substantially improves the operating margins by: (1) Using a double-turn low-inductance interferometer as one of the sensing gates to improve the circuit's ability to discriminate between a "1" and a "0" stored in the loop. Note that the low inductance device (Gate A) has a much lower "floor" to the threshold curve and therefore switches when current Ic is far from its threshold curve.

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Low Temperature SLAVE Circuit

A SLAVE circuit in the Josephson latch is used to detect if current is stored in a superconducting storage loop during the transition time of the AC power supply. Previous SLAVE circuits used a single junction to sense the stored current; this design has poor operating margins and is relatively slow. This SLAVE circuit, shown in Fig. 1, substantially improves the operating margins by: (1) Using a double-turn low-inductance interferometer as one of the sensing gates to improve the circuit's ability to discriminate between a "1" and a "0" stored in the loop. Note that the low inductance device (Gate A) has a much lower "floor" to the threshold curve and therefore switches when current Ic is far from its threshold curve. The better discrimination that is provided by using the low inductance device allows substantially larger variations in junction critical currents to be tolerated. (2) Using a single resistor to set all current levels in the critical path and thus reduce the sensitivity of the circuit to resistor variations. In this SLAVE circuit, the current Ia is determined only by resistor Ra. Thus, the competition between the switching of Gates A and C is independent of resistor variations. The operation of the circuit for the two cases of a "0" and a "1" in the storage loop of the latch is described below: "0" in LOOP Gate C switches before Gate A, then the amplifying Gate E switches. The output of these devices is used to switch G...