JEDEC has launched an up to date model of its JESD235 specification this week describing HBM and HBM2 DRAM. With the brand new model of the usual, reminiscence producers can enhance the capability of future HBM stacks to 24 GB and enhance their bandwidth to 307 GB / s per stack.
On the capability entrance, the brand new model of the specification, JESD235B, has been added to help 12-Hello-Chipstacks. With 4 layers greater than the earlier restrict of Eight hi-stacks, reminiscence producers can produce 12 Gb stacks with present densities and 24 Gb stacks sooner or later when 16 Gb layers can be found. Though 12 Hello-Stacks at the moment are a part of the HBM specification, the group nonetheless lists the bodily dimensions of a 12-Hello KGSD ("Good Good Stacked Die") as "TBD", so it’s not instantly clear for the time being Whether or not 12-Hello stacks observe the identical guidelines for the utmost stacking peak of 720μm / 745μm as the present 2/four/Eight-Hello configurations. In any other case, the configuration of the stack itself stays unchanged; The brand new KGSDs will proceed to incorporate as much as eight 128-bit channels and a 1024-bit bodily interface.
By way of efficiency, the HBM normal now additionally helps knowledge switch charges of as much as 2.four Gbps per pin (i.e., 307 GB / s per stack), in comparison with 2 Gbps supported by the JESD235A. It’s noteworthy that Samsung's HBM2 reminiscence chips from Aquabolt and SK Hynix already help 1.2Gbps 1.2V speeds, so the brand new specification is not going to considerably change efficiency. Nonetheless, with this replace, the two.four Gbps knowledge charge can lastly be integrated into the official normal, and the brand new specification will permit different DRAM distributors to additionally launch 2.four Gbps merchandise.
Total, the up to date specification signifies that a completely built-in 4096-bit HBM reminiscence subsystem in response to the JESD235B specification can now comprise 96 GB of reminiscence with a peak bandwidth of 1.228 TB / s.
Nonetheless, it stays to be seen when reminiscence producers are prepared with their 12 Hello HBM reminiscence chips. To this point no one has introduced 12-Hello merchandise. Nonetheless, I might not count on JEDEC so as to add even greater stacks to the usual except somebody was constructing that reminiscence.