Bit-line interaction in magnetic-film memories

The noise generated in the bit-sense lines of a magnetic-film memory during the write operation consists of two components: the drive noise due to energizing the line under consideration, and the interaction noise caused by coupling between the bit-sense lines. The latter component is the subject of this paper. By an analysis of pulse propagation in a transmission system consisting of two identical parallel strip lines above a stratified ground plate, it is shown that the relative significance of the interaction noise increases with line-to-ground spacing and that its time derivative at read time can be made to vanish by an appropriate stratification of the ground plate. The stratification which achieves this is close to the one for which the time derivative of the drive noise has a minimum. Hence the time derivative of the write noise, which should be as small as possible for best rejection by the sense system, can be reduced by ground-plate stratification. It can also be reduced by keeping the ground plate at a low temperature.