Narrow 512-bit interface enables dropping expensive interposers for organic substrates
JEDEC has released its new specification that aims to push down the pricing of the ultra-expensive HBM that powers the fastest AI processors. While the new standard will not help relieve the DRAM shortage as it uses large HBM4 DRAM devices, it can make high-bandwidth memory a bit cheaper as it enables attaching SPHBM4 memory stacks without advanced packaging and using inexpensive organic substrates.
The standard’s body published the specification of SPHBM4, Standard Package High Bandwidth Memory (JESD330-4), that combines HBM4 DRAM ICs with standard packaging and a fast ‘narrow’ 512-bit interface. Here are the details.
HBM4 performance with a 512-bit wide interface
Although 1024-bit and 2048-bit interfaces used by HBM3 and HBM4 memory deliver unbeatable performance, their wide interfaces consume significant silicon area inside processors, they require expensive interposers, and advanced packaging technologies with limited capacity, such as TSMC’s CoWoS, for integration with host processors. The upcoming SPHBM4 memory continues to use the same HBM4 DRAM stacks as JESD270-4, but swaps the conventional HBM base die for a new SPHBM4 PHY/buffer die featuring a narrower 512-bit interface that enables mounting on standard organic substrates without using sophisticated packaging methods for integration. To offset the effect of the narrower interface, SPHBM4 supports considerably higher data transfer rates ranging from 22.4 GT/s to 46.0 GT/s.
READ MORE Source: Tom’s Hardware>>
