Tablet and smartphone demand drives new trends in mobile memory

As the number of mobile devices worldwide surges, the need for better, cheaper memory for these devices soars. Numerous alternatives are available for mobile memory. Industry standards abound, and others are still in development. By all accounts, this market is on the upswing, so where do all of the memory technologies and form factors fit in, and what’s on the horizon for mobile memory?

According to estimates from IHS iSuppli Research, the growth of sales for smartphones and tablets will increase revenue in the mobile-memory market by 26% in 2011 to $16.4 billion, compared with $13 billion in 2010 and, iSuppli projects, $19.3 billion in 2012 (Reference 1). Gregory Wong, principal analyst at Forward Insights, agrees that consumer devices, particularly smartphones and tablets, are driving memory demands. He observes two basic types of memory available for these devices: e•MMC (embedded multimedia card), a low-power JEDEC (Joint Electron Device Engineering Council) Solid State Technology Association standard, and solid-state drives. Solid-state drives offer better IOPS (input/output operations per second) for tablets than does the JEDEC standard but at a higher cost and power consumption (Figure 1).




Increasing performance and maintaining low power are the major challenges for memory designers, and many see universal flash storage, which accomplishes these goals, as the next big thing. Vendor support is weaker than it was when JEDEC first proposed the standard, according to Wong. As such, a solid-state drive with a low-power SATA (serial-advanced-technology-attachment) interface could be an alternative. “For example, the idle power of the SATA PHY [physical layer] is quite large,” he says. “You could make it ‘low power’ by turning off the PHY when [it is] idle.”

Setting the standards
JEDEC, a volunteer organization, sets open standards for the microelectronics industry and recently hosted a standardization meeting in Vancouver, BC, Canada, focusing primarily on memory-related topics. “The ongoing standards-development work within the JEDEC committees, focused on mobile memory, has significant strategic value to the industry and will help make possible a wide range of innovative new products,” says Desi Rhoden, chairman of the JC-42 Committee for Solid State Memories. Published JEDEC standards that relate to mobile memory include LPDDR2 (low-power double data rate 2), universal flash storage, and e•MMC.

JEDEC designed the LPDDR2 JESD209-2E standard to enhance the design of mobile devices, such as smartphones, cell phones, PDAs (personal digital assistants), GPS (global-positioning-system) units, and handheld gaming consoles, by enabling increased memory density, improved performance, greater compactness, overall reduction in power consumption, and longer battery life. As a result, it offers advanced power-management features, a shared interface for nonvolatile and volatile memory, and a range of densities and speeds. The JC-42.6 Subcommittee for Low Power Memories published the standard in April 2009 and updated it in April 2011.

The JEDEC JESD220 universal-flash-storage standard targets both embedded and removable flash-memory-based storage in mobile devices that require high performance and low power consumption, such as smartphones and tablets. The standard uses the MIPI (Mobile Industry Processor Interface) Alliance’s M-PHY (MIPI-physical-layer) and UniPro (Unified Protocol) specifications to form its interconnect layer. Because it combines this advanced interface with low active-power level and a near-zero idle-power level, universal flash storage shows promise in achieving significant reductions in device power consumption. JEDEC first published the standard in February 2011.

In June, JEDEC announced the publication of the JESD84-B45 Embedded Multimedia Card Electrical Standard Version 4.5, a low-cost data-storage and communication standard that targets applications such as smartphones, cameras, organizers, PDAs, digital recorders, MP3 players, pagers, and electronic toys. The latest version of the standard increases interface bandwidth from 104 Mbytes to 200 Mbytes to achieve high mobility, high performance, low power consumption, and high data throughput. This free standard helps to improve the interaction between the host processor and the memory device at the interface, configuration, and protocol levels to gain system performance and reliability (Reference 2).

JEDEC is also developing LPDDR3 to meet the higher bandwidth requirements of next-generation smartphones and tablets. JEDEC LPDDR3 effectively extends the LPDDR2 standard’s bandwidth, reaching 6.4 Gbytes/sec and allowing 12.8 Gbytes/sec for a dual-channel configuration. It will support both POP (package-on-package) and discrete packaging types and preserve the power-efficient features and signaling interface of LPDDR2.

The JEDEC WideIO (wide-input/output) standard aims to satisfy industry demands for increased levels of integration and improved bandwidth, higher latency, lower power consumption, lower weight, and smaller form factor. JEDEC expects WideIO to provide performance, energy efficiency, and compactness for smartphones, tablets, handheld gaming consoles, and other high-performance mobile devices. WideIO mobile DRAM uses chip-level 3-D stacking with TSV (through-silicon-via) interconnects and memory chips on SOCs (systems on chips). WideIO will suit use in systems that require memory bandwidth as high as 12.8 Gbytes, including 3-D gaming, 180p high-definition video, and similar applications.

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Reference
1. Yang, Michael, “Mobile Memory to Proliferate to $16.4 Billion Market in 2011, Up 26 Percent,” IHS iSuppli, April 28, 2011.