Stripe-line coil for magnetic-field generation in bubble memory devices
Coil etched from conductive film has better field uniformity than wire-wound coils and less coil loss at high-frequency operation.
Chen, T. T.↗
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Low-loss stripe-line coil for magnetic bubble memory
Stripe-line pattern is etched on both sides of double-sided film. Since conductor thickness is only half that of single-sided film, problems in wrapping and etching are greatly reduced.
Chen, T. T.↗
Open coil structure for bubble-memory-device packaging
Concept has several important advantages over close-wound system: memory and coil chips are separate and interchangeable; interconnections in coil level are eliminated by packing memory chip and electronics in single structure; and coil size can be adjusted to optimum value in terms of power dissipation and field uniformity.
Chen, T. T.↗
Variable-gap bias structure for magnetic bubble memory package
Size and thickness of field adjusting plate can be varied. Memory chip specification is relaxed, since chips in structure need not be matched in bias margin.
Chen, T. T.↗
Bubble memory module
Design, fabrication and test of partially populated prototype recorder using 100 kilobit serial chips is described. Electrical interface, operating modes, and mechanical design of several module configurations are discussed. Fabrication and test of the module demonstrated the practicality of multiplexing resulting in lower power, weight, and volume. This effort resulted in the completion of a module consisting of a fully engineered printed circuit storage board populated with 5 of 8 possible cells and a wire wrapped electronics board. Interface of the module is 16 bits parallel at a maximum of 1.33 megabits per second data rate on either of two interface buses.
Bohning, O. D.↗
Bubble domain technology for spacecraft onboard memory
Bubble device technologies for spacecraft onboard memory offer improved reliability and memory functional characteristics. Recent advances include Permalloy gap devices (commercially available) whose improved performance and higher density are attributable to an asymmetric chevron pattern. Secondly, an order of magnitude increase in density at less power than the Permalloy technology is possible with the ion implant technology. A third technology, the self-structured current access system, offers another order of magnitude improvement in density and data rate, and is being studied. Capacity estimates for Permalloy gap, ion implant, and self-structured current access systems are, respectively, 10 to the 8th, 10 to the 9th, and 10 to the 10th bits, and power per unit data rate efficiencies are 140, 60, and 2 W/Mbps. A flexible modular organization system, compatible with all of these device technologies, is analyzed, and, as the system is contained in a bubble, relatively simple retrofitting is foreseen.
Hayes, P. J.↗
Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 2: The optimization of material-device parameters for application in bubble domain memory elements for spacecraft data recorders
Bubble domain materials and devices are discussed. One of the materials development goals was a materials system suitable for operation of 16 micrometer period bubble domain devices at 150 kHz over the temperature range -10 C to +60 C. Several material compositions and hard bubble suppression techniques were characterized and the most promising candidates were evaluated in device structures. The technique of pulsed laser stroboscopic microscopy was used to characterize bubble dynamic properties and device performance at 150 kHz. Techniques for large area LPE film growth were developed as a separate task. Device studies included detector optimization, passive replicator design and test and on-chip bridge evaluation. As a technology demonstration an 8 chip memory cell was designed, tested and delivered. The memory elements used in the cell were 10 kilobit serial registers.
Besser, P. J.↗
Magnetic bubble domain memories
Some attractive features of Bubble Domain Memory and its relation to existing technologies are discussed. Two promising applications are block access mass memory and tape recorder replacement. The required chip capabilities for these uses are listed, and the specifications for a block access mass memory designed to fit between core and HPT disk are presented. A feasibility model for a tape recorder replacement is introduced.
Ypma, J. E.↗
A current access, self-structured, multilayered bubble domain memory
Preliminary experimental results are reported on a self-structured, multilayer bubble memory with buried data layer. Stripe domains are used to move carrier bubbles by magnetostatic coupling. An expression is derived for that coupling as a function of thickness of the GGG separation layer. Experimental values of coupling are given as a function of bias field. An expression for stripe curvature as a function of bias field is derived. The performance of seven different current access stripe propagation circuits is reported.
Stermer, R. L., Jr.↗
Feasibility of self-structured current accessed bubble devices in spacecraft recording systems
The self-structured, current aperture approach to magnetic bubble memory is described. Key results include: (1) demonstration that self-structured bubbles (a lattice of strongly interacting bubbles) will slip by one another in a storage loop at spacings of 2.5 bubble diameters, (2) the ability of self-structured bubbles to move past international fabrication defects (missing apertures) in the propagation conductors (defeat tolerance), and (3) moving bubbles at mobility limited speeds. Milled barriers in the epitaxial garnet are discussed for containment of the bubble lattice. Experimental work on input/output tracks, storage loops, gates, generators, and magneto-resistive detectors for a prototype device are discussed. Potential final device architectures are described with modeling of power consumption, data rates, and access times. Appendices compare the self-structured bubble memory from the device and system perspectives with other non-volatile memory technologies.
Nelson, G. L.↗
Uniform rotating field network structure to efficiently package a magnetic bubble domain memory
A unique and compact open coil rotating magnetic field network structure to efficiently package an array of bubble domain devices is disclosed. The field network has a configuration which effectively enables selected bubble domain devices from the array to be driven in a vertical magnetic field and in an independent and uniform horizontal rotating magnetic field. The field network is suitably adapted to minimize undesirable inductance effects, improve capabilities of heat dissipation, and facilitate repair or replacement of a bubble device.
Wolfshagen, Ronald G.↗
Investigation of chemical vapor deposition of garnet films for bubble domain memories
The important process parameters and control required to grow reproducible device quality ferrimagnetic films by chemical vapor deposition (CVD) were studied. The investigation of the critical parameters in the CVD growth process led to the conclusion that the required reproducibility of film properties cannot be achieved with individually controlled separate metal halide sources. Therefore, the CVD growth effort was directed toward replacement of the halide sources with metallic sources with the ultimate goal being the reproducible growth of complex garnet compositions utilizing a single metal alloy source. The characterization of the YGdGaIG films showed that certain characteristics of this material, primarily the low domain wall energy and the large temperature sensitivity, severely limited its potential as a useful material for bubble domain devices. Consequently, at the time of the change from halide to metallic sources, the target film compositions were shifted to more useful materials such as YGdTmGaIG, YEuGaIG and YSmGaIG.
Besser, P. J.↗
Redundancy approaches in bubble domain memories
Fabrication of integrated circuit chips to compensate for faulty memory elements is discussed. Procedure for testing chips to determine extent of redundancy and faults is described. Mathematical model to define operation is presented. Schematic circuit diagram of test equipment is provided.
Almasi, G. S.↗
Development of a high capacity bubble domain memory element and related epitaxial garnet materials for application in spacecraft data recorders. Item 1: Development of a high capacity memory element
Several versions of the 100K bit chip, which is configured as a single serial loop, were designed, fabricated and evaluated. Design and process modifications were introduced into each succeeding version to increase device performance and yield. At an intrinsic field rate of 150 KHz the final design operates from -10 C to +60 C with typical bias margins of 12 and 8 percent, respectively, for continuous operation. Asynchronous operation with first bit detection on start-up produces essentially the same margins over the temperature range. Cost projections made from fabrication yield runs on the 100K bit devices indicate that the memory element cost will be less than 10 millicents/bit in volume production.
Besser, P. J.↗
Improved Reading Gate For Vertical-Bloch-Line Memory
Improved design for reading gate of vertical-Bloch-line magnetic-bubble memory increases reliability of discrimination between binary ones and zeros. Magnetic bubbles that signify binary "1" and "0" produced by applying sufficiently large chopping currents to memory stripes. Bubbles then propagated differentially in bubble sorter. Method of discriminating between ones and zeros more reliable.
Wu, Jiin-Chuan↗
Continuous-data FIFO bubble shift register
Simple loop first-in-first-out (FIFO) bubble memory shift register has continuous storage capability. Bubble shift register simplifies chip-control electronics by enabling all control functions to be alined at same bit. FIFO shift register is constructed from passive replicator and annihilator combinations.
Chen, T. T.↗
A magnetic bubble domain flight recorder
A feasibility model of an all-electronic bubble memory system has been constructed. It uses a small 60k bit bubble recorder consisting of 6 chips of 10k bits each mounted in three separate packages operating as a FIFO at a 150 KHz bubble data rate. In addition to serving as a direct tape recorder replacement, the bubble recorder can be programmed for random access to each individual chip for ranom block access operation or for self-checking or by-passing any malfunctioning memory chip. Read and write operations can be performed asynchronously from very low frequency up to basic recording field frequency. A large 50M bit prototype is planned.
Chen, T. T.↗
Three-Dimensional Vertical-Bloch-Line Memory System
In proposed magnetic memory system without moving parts, data is stored in stack of two-dimensional vertical-Bloch-line (VBL) memory chips or modules. System similar to one described in "Three-Dimensional Magnetic-Bubble Memory System" (NPO-18533). Each VBL module in this memory system silimar to module described in "Vertical-Bloch-Line Memory" (NPO-18467). Advantages include high storage density, high speed, nonvolatility, and insensitivity to ionizing radiation.
Katti, Romney R.↗