Write noise in magnetic-film memories due to current diffusion in the ground plate

Abstract

In magnetic-film memories which have the bit current returning through a ground plate, the write noise, i.e., the sense-line voltage caused by the bit-current pulse, contains a slowly decaying component. Theoretical and experimental results show that the time derivative of this component, which should be as small as possible for best rejection by the sense system, can be reduced by 1) appropriately stratifying the ground plate, 2) keeping the ground plate at a low temperature, or 3) terminating the bit-sense line with a suitable RC network. The experiments were carried out using a scale model of the bit-sense line, with the physical dimensions, the time scale, and the resistivity of the conductors all being increased by the same factor. Electrical properties of such a scale model are identical to those of the simulated system.