The need for speed—DDR4 and LPDDR3
Whether the application is smart phones, PCs, or enterprise storage, the only memory characteristic more important than density is speed. September saw the official release of the DDR4 DRAM standard from JEDEC. The current version of the standard is based on a per-pin data rate of 1.6 GT/s, with an initial maximum objective of 3.2 GT/s. Now, there was some quibbling at the time of release about the fact that the starting data rate of 1.6 GT/s is already being delivered by DDR3 devices. That’s less a knock on DDR4 than a tribute to the work done by vendors and the standards team on DDR3, though—remember, when DDR3 debuted in 2007, its initial speed was 0.8 GT/s. The DDR4 team has loftier aims than 3.2 GT/s, so look for new versions of the standard to come out on a regular basis.
Recognizing the market shift toward portable devices, the DDR4 team focused much of their effort on adding refinements to reduce power consumption. The standard calls for a supply voltage of just 1.2 V compared to 1.8 V for DDR2.
Speaking of specifications for low-power devices, 2012 also saw the release of JEDEC’s latest low-power DRAM standard, LPDDR3
. With a focus on write-leveling, CA training, and on-die termination
, LPDDR3 gives the community the tools they need to develop memory products for the mobile device industry.
In the case of both standards, vendors like SK Hynix, Samsung, Cadence, and Micron Technologies had put out products well before the formal release of the documents. For now, DDR3 and LPDDR2 are still the workhorse technologies, but look for that to change.