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Clockwise-Counterclockwise Josephson NDRO Cache Write Operation

IP.com Disclosure Number: IPCOM000042011D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Kadlec, J: AUTHOR

Abstract

Sequencing a WRITE-operation for a Josephson NDRO cache with both clockwise (CW) and counterclockwise (CCW) flux quanta minimizes the need for damping. The mode structure of a NDRO cache memory cell (Fig. 1A) in the Ic-Ig current plane contains regions of operating points with uniquely defined quantum states (Fig. 1B) as well as regions where more than one state can exist. The investigations so far are inconclusive as to the question whether a design may utilize the more-than-one-state regions (in addition to the unique regions) for a reliable WRITE-operation with a predetermined number of flux quanta. The results of a detailed analysis of the memory cell lead to the following conclusions: 1) The quantum states of the cell in the phase space are successive and may change only by 1do at a time.

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Clockwise-Counterclockwise Josephson NDRO Cache Write Operation

Sequencing a WRITE-operation for a Josephson NDRO cache with both clockwise (CW) and counterclockwise (CCW) flux quanta minimizes the need for damping. The mode structure of a NDRO cache memory cell (Fig. 1A) in the Ic-Ig current plane contains regions of operating points with uniquely defined quantum states (Fig. 1B) as well as regions where more than one state can exist. The investigations so far are inconclusive as to the question whether a design may utilize the more-than-one-state regions (in addition to the unique regions) for a reliable WRITE-operation with a predetermined number of flux quanta. The results of a detailed analysis of the memory cell lead to the following conclusions:
1) The quantum states of the cell in the phase space are successive and may change only by 1do at a time. In order to write the mdo-state coming from the initial ndo-state into a rather heavily damped cell, it is necessary to place the operating point in the existence region of the mdo-state and to cross the upper boundary of the (m-1)do-state if n<m; or to cross the lower boundary of the (m+1)do-state if n>m . In particular, an appropriately damped 2do-cell may utilize the (2/3)+(2) - regions for WRITE-1 and the (-1/0)+(0) - regions for WRITE-0 (Fig. 1B). 2) The energetic considerations imply that the dependence of the WRITE-operation on damping can practically be eliminated by changing the sequence of the current...