Experiments on high speed bubble propagation

A high speed bubble drive circuit is proposed in which, by the application of an in-plane field, a bubble propagates at a speed higher than the saturation velocity with no in-plane field. The circuit consists of two meandering conductors. By the application of sine and cosine currents, the conductors of the optimum sizes produce a magnetic field which progresses at nearly a constant velocity. The operating bias margins of the circuit are improved by a permalloy rail which is placed along the center of the circuit. 42 mA is required to drive a bubble at 1 MHz. The current can be reduced to 10 mA, by applying a 100 Oe in-plane field. It is feasible to drive a bubble at 5 MHz with 20 mA current and a 200 Oe in-plane field. A major-minor independent chip organization in which the conductor circuit is used as a major line is described. The major line is linked to the conventional minor loops by a permalloyless transfer gate. The organization has the advantages of not only transfering bubbles at very high speed but also increasing the versatility of the memory chip function.