Combination of field and current access magnetic bubble circuits

A high-frequency current-access output gate is applied to a field-access memory operating at lower frequencies. This takes advantage of materials whose maximum velocity is not reached at the obtainable rotating-field frequency. The access and cycle times can decrease easily by a factor of 2 to 6. A number of elements has been designed, necessary to perform a combination of field-access and current-access circuits. Conductor propagation structures and field-current transfer gates have been tested on high mobility 7μm-bubble La, Ga-YIG. These elements, though not optimised, already have overlapping margins. Single-mask conductors consisting entirely of permalloy or a sandwich of permalloy on gold both propagate bubbles up to about 1 MHz frequency.