Current accessed magnetic bubble devices: Projections of performance

A critical analysis is made of the current accessed dual conductor perforated sheet magnetic bubble devices introduced by Bobeck, et al. First, the performance of the existing reported devices is considered. It is shown that although the average power dissipation to propagate one bit of data is relatively high, that with proper chip organization, the average on-chip power dissipation can be kept to tolerably low levels. However, certain components such as the nucleator and the bubble stretcher have such high power dissipation that they are expected to lead to local power dissipation problems on the chip. Assuming these local power dissipation problems can be solved, an analysis of the performance shows that these new devices potentially offer substantially higher data rates and substantially shorter access time than can be obtained with field accessed devices. Scaling rules are developed for the various components on current accessed devices. These scaling rules indicate that for most components, power dissipation per unit area will increase in inverse proportion to the circuit period. Power dissipation in the stretcher, on the other hand, increases even more rapidly with decreasing period and in a 1 Mbit device with 4 μm period would consume 80 percent of the on-chip power. Assuming the problems with power dissipation per unit area can be solved, the scaling rules suggest that the current accessed devices will enjoy an increasing performance advantage over field accessed devices as circuit period is reduced and the chip capacity is increased. This is because the data rate of current accessed devices is projected to increase in inverse proportion to circuit period, whereas the data rate of field accessed devices is dependent on the rotating field drivers and expected to remain constant.