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Compensated Memory Drive Technique

IP.com Disclosure Number: IPCOM000093796D
Original Publication Date: 1966-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Pugh, EW: AUTHOR [+2]

Abstract

In flat film memories where a magnetic memory element 10 is supported by a conductive ground plane 12, as shown at Al, the phenomena of image current disturbances occur. Specifically when a drive current is initially applied by driver 14 to memory drive line 16 image current 18 is transiently induced directly under element 10. Drawing B a sectional view illustrates the aiding effect on element 10 of the energizing field due to the current in line 16 and image current 18.

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Compensated Memory Drive Technique

In flat film memories where a magnetic memory element 10 is supported by a conductive ground plane 12, as shown at Al, the phenomena of image current disturbances occur. Specifically when a drive current is initially applied by driver 14 to memory drive line 16 image current 18 is transiently induced directly under element 10.

Drawing B a sectional view illustrates the aiding effect on element 10 of the energizing field due to the current in line 16 and image current 18.

The cumulative effect of these fields is to apply a double strength field to element 10. As in drawing C, this is only a transient phenomena and quickly decays due to the spreading of image current 18 in plane 12. The application of the transient double-strength field to the individual memory elements degrades overall memory operation.

From drawing C, it is determined that the transient field strength decay can be likened to an exponential phenomena in which the rate of decay of magnetic field under line 16 is dependent upon the combined drive line and ground plane inductances. As shown at A2, an equivalent circuit of this memory phenomena is represented by inductor 20 and resistor 22 connected across driver 14. Resistances Rs and Ro are, respectively, the internal impedance of driver 14 and the characteristic impedance resistance, of line 16.

To compensate for the transient characteristic of the inductance of plane 12 and line 16 a compensating RC network compr...