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Superconducting Memory Array using Weak Links

IP.com Disclosure Number: IPCOM000075510D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 19K

Publishing Venue

IBM

Related People

Anacker, W: AUTHOR [+2]

Abstract

Superconducting memory loops, each including a current-limiting weak link, such as a Josephson current device, have particular geometries in order to provide one flux quantum operation.

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Superconducting Memory Array using Weak Links

Superconducting memory loops, each including a current-limiting weak link, such as a Josephson current device, have particular geometries in order to provide one flux quantum operation.

Superconducting ring 12 has at least one Josephson current device 14, e.g., a thin film planar device, a point contact junction, a thin film bridge or a constriction-type weak link. For one flux quantum operation, where a single flux quantum represents a binary one and the absence of a quantum a binary 0, the inductance L, capacitance C and damping R must meet the requirements 3/4 QO < or = L 10 < or = 7/4 QO 1/R/2/ - 4C/L > 0. where IO is the loop current and QO the flux quantum of 2.10/-15/ Weber. Without this requirement no flux quantum or multiple flux quanta would be trapped in the loop, or oscillations would occur.

The memory cells 10 in an array are accessed by coincident currents on X and Y lines, causing sufficient flux linking the memory cell to either trap one flux quantum in the cell (write 1) or no flux quantum (write 0).

The sum of coincident currents Ix and Iy required to switch the state of any cell is at least equal to the maximum Josephson current in the memory loop. Writing a binary 1, is accomplished by pulsing both X and Y conductors; to write a binary 0 either X or Y is pulsed. For all writing operations, coincident cleaning pulses are applied to an X and Y conductor to ensure that selected memory cells are in the...