JEDEC Announces Publication of DDR4 Memory Standard
The JEDEC Solid State Technology Association today announced the initial publication of its widely-anticipated Synchronous DDR4 (Double Data Rate 4) standard. JEDEC DDR4 (JESD79-4) has been defined to provide higher performance, with improved reliability and reduced power, thereby representing a significant achievement relative to previous DRAM memory technologies. The new DDR4 standard is available for free download here.
The per-pin data rate for DDR4 is specified as 1.6 giga transfers per second to an initial maximum objective of 3.2 giga transfers per second. With DDR3 exceeding its original targeted performance of 1.6 GT/s, it is likely that higher performance speed grades will be added in a future DDR4 update. Other DDR4 attributes tightly intertwined with the planned speed grades, enabling device functionality as well as application adoption, include: a pseudo open drain interface on the DQ bus, a geardown mode for 2,667 MT/s per DQ and beyond, bank group architecture, internally generated VrefDQ and improved training modes.
The DDR4 architecture is an 8n prefetch with two or four selectable bank groups. This design will permit the DDR4 memory devices to have separate activation, read, write or refresh operations underway in each unique bank group.
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