August 22, 2011 — JEDEC Solid State Technology Association shared selected elements of its Double Data Rate 4 (DDR4) standard, to be published in full in 2012. Reduced power usage, better performance, and faster operation are the main aims of DDR4 for servers, laptops, desktop PCs, and consumer products.
JEDEC says DDR4 memory speed, architecture, and voltage are being defined in a manner that simplifies migration and standard adoption.
The proposed DDR4 voltage roadmap will hold VDDQ constant at 1.2V and allow for a future reduction in the VDD supply voltage. Per-pin data rates, over time, will be 1.6 giga transfers per second to an initial maximum objective of 3.2 giga transfers per second. DDR4 can expect higher performance level proposals, since DDR3 exceeded its expected peak of 1.6 GT/s. Three data width offerings are under development: x4, x8 and x16. Also look for a new JEDEC POD12 interface standard for DDR4 (1.2V), differential signaling for the clock and strobes, a new termination scheme, nominal and dynamic ODT and a new Park Mode, burst length of 8 and burst chop of 4, data masking, DBI to help reduce power consumption and improve data signal integrity, new CRC for data bus, new CA parity for command/address bus, and DLL off mode supported. A pseudo open drain interface on the DQ bus, a geardown mode for 2667 Mhz data rates and beyond, internally generated VrefDQ, bank group architecture, and improved training modes are also slated for the JEDEC standard.
The DDR4 architecture is an 8n prefetch with bank groups, including the use of two or four selectable bank groups. DDR4 memory devices can have separate activation, read, write or refresh operations underway in each of the unique bank groups.
The next committee meeting will be held in Chicago in September 2011. When published, the new standard will be available for free download at www.jedec.org. JEDEC will host a DDR4 Technical Workshop following the publication of the standard.
JEDEC develops standards for the microelectronics industry. For more information, visit www.jedec.org.
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