The properties of X-bar bubble memory chips

The properties of a 16-kbit bubble memory chip having a conventional major-minor loop organization are described. The chip can be operated up to a shift rate of 300 kHz which corresponds to a mean access time of 0.5 ms to blocks of 128 bits. Overall bias field margins of 13 percent were obtained, especially as the result of an appropriately selected layout of the transfer gates which is described in detail. Additional data are given concerning the influence of ambient temperature and of the number of propagation steps. The possibility of fabricating X-bar transfer gates using a single photomask step is demonstrated.