Signal sensing and magnetic film memory array design

A signal-to-noise analysis is presented to show its influence on the design of magnetic film memory arrays. The device geometry and array dimensions are varied independently to find the design limits within which reliable signal detection can be performed, that is, the range within which adequate signal-to-noise ratio is obtained at the sense amplifier. The result is a plot of the required number of READ pulses for any combination of line width and line length in the range of interest. Line widths between 1/2- and 4-Mil and array sizes up to 4096 × 4096 bits were investigated. Multipulse readout is required for line widths less than 1.5-mils. A 256 × 256 array of 1/2-mil lines on 1-mil centers requires 12 signal pulses of 3-ns duration each, whereas a 1024 × 1024 array of 1-mil lines on 2-mil centers requires 7 signal pulses. It should be noted that in addition to adequate signal-to-noise ratio, a minimum of signal is needed (not obtainable through multiple READs) commensurate with the gain of the sense amplifier. These considerations are all combined in a set of design curves which can be used to make design tradeoffs between device size, array size, and cycle time.