AMD Pivots From HBM to LPDDR5X For New Versal Premium Gen 2 Memory on Package Chips

Versal Premium Gen 2 Memory on Package

Absent the ability to use HBM, AMD’s third generation of memory on package programmable logic chips are taking a different tack by incorporating LPDDR5X memory instead.

From a hardware perspective this is very much a trade-off that gives up memory performance in favor of availability. But it is one that AMD believes is a better fit for their customers’ needs, as well as the company’s own supply chains. After all, the company still sees a need for the more highly integrated chips, even if they cannot justify using HBM in their construction any longer.

From a production and supply standpoint, the switch to LPDDR5X brings two distinct benefits. The first, of course, is that LPDDR5X memory should be around for far longer than HBM3e will be. It is used in a far wider variety of products, the big three memory manufacturers are expected to keep it in production for much longer. Eventually, production should also be picked up by second-tier boutique vendors like Nanya and Winbond (not to mention Chinese suppliers like CXMT).

The second production benefit is that this makes chip assembly easier for AMD. Whereas the HBM chips required advanced packaging techniques to assemble the chips – namely, chip-on-wafer-on-substrate (CoWoS) production for the silicon interposer – the Versal Premium chips with LPDDR5X placed on-package can be assembled with traditional organic packaging. This is a bit of a cheaper process for AMD, but it also lets their adaptive SoC offerings bypass another bottleneck in advanced packaging availability.

Meanwhile, though it is not quite as much of a customer-facing benefit, AMD’s existing high-end Versal Premium Gen 2 silicon already has a 256-bit DDR5/LPDDR5X memory controller on it. This means that AMD is able to produce the memory on package variant of the chips without needing to fab a separate die. Which further means that AMD does not have to keep producing additional die variations for years (and years) to come.

The performance trade-off, then, is primarily memory bandwidth. With AMD’s Versal HBM products, the company was able to offer up to 32GB of memory with 819GB/second of memory bandwidth; meanwhile the new Versal Gen 2 Memory on Package chips will offer 32GB of LPDDR5X with just 288GB/second of memory bandwidth. In practice it is a sidegrade in terms of memory capacity, and a step back in terms of memory bandwidth.

But the switch to LPDDR5X also brings some notable benefits, as well. Availability is obviously the big one here, as AMD expects to be able to offer their Versal Gen 2 Memory on Package parts for at least 15 years as both the fabs and memory needed to produce it should be available for many years to come. And if LPDDR5X memory continues to be available past 2040, then AMD would even have the ability to extend the chips’ availability past 15 years, as evidenced by their recent extension. Suffice it to say, this alone is a massive change from even the initial projected availability of the earlier HBM parts.

The other major feature benefit here is that there are LPDDR5X memory chips rated to run at industrial temperature grades, something that HBM chips could never do. Consequently, whereas the Versal HBM chips were only rated to operate at an extended temperature range of 0°C to 95°C (and short excursions to 105°C), the Versal Premium Gen 2 Memory on Package chips can operate from -40 all the way to 110°C, making them uniquely suitable for use in sub-zero conditions.

Target Use Cases: Compact Products & Turn-Key Hardware Designs

Memory technologies aside, the target market for their memory on package Versal Premium Gen 2 chips largely overlaps with the broader market for the Versal chips, but with a much stronger emphasis on compact products and a faster time-to-market.

On the form factor front, thanks to the use of just four 64-bit LPDDR5X memory chips, the Versal Premium Gen 2 Memory on Package chips measure just 55mm x 57.5mm. Comparatively, a traditional 8x32b setup with off-package memory takes up roughly 2.5 times the board area, and requires the hardware vendor to lay down the traces for a 256-bit memory bus.

With its more compact form factor, AMD is particularly keen to chase the add-in card market with the Versal Premium Gen 2 Memory on Package chips. The chips are small enough to be placed on OCP NIC form factor cards, as well as HHHL PCIe cards and EDSFF NICs. Meanwhile in a more niche application, the chips also fit into the 3U version of the VPX form factor used in military applications.

The other key market for AMD is customers who need a shorter time to market. Because the Versal Premium Gen 2 Memory on Package is largely self-contained, implementing the chips only requires building all of the power and I/O connections around it, but not routing memory buses or placing LPDDR5X memory chips. Which is a routine enough task in product designs that are already implementing multiple lanes of PCIe 6 connectivity and 600Gb Ethernet, but it can be a time-consuming part of the design process all the same. The memory on package version of the Versal, in contrast, is much closer to being a turn-key solution.

Past that, because both the regular and memory on package versions of the Versal Premium Gen 2 chips are based on the same silicon, the feature sets between the two are otherwise identical. The memory on package version is exactly what it says on the tin: a version of the high-end adaptive SoC with on-package memory.

Most notably, that includes PCIe Gen6 and CXL 3.1 support, which are hard IPs on the chips and introduced in the Versal Gen 2 chips. And indeed, I/O bandwidth is the premiere feature of the entire Gen2 range, as these are AMD’s adaptive SoCs with the largest allocation of I/O PHYs, SerDes, and pins.

Altogether, AMD is offering three MoP SKUs, all with 32GB of memory: the 2VP3422, 2VP3522, and 2VP3622. These are all based on the 2VP3402, 2VP3502, and 2VP3602 respectively, just with the addition of on-package memory.

As an aside, the memory on package versions will have a slight edge in memory bandwidth. While the standalone Versal Gen 2 chips are only rated to run at up to LPDDR5X-8533, the MoP versions are rated to run at LPDDR5X-9000, owing the shorter memory traces between the memory and SoC.

Ultimately, AMD expects the Versal Premium Gen 2 Memory on Package to be applicable to a large number of markets. Similar to the standard chips, AMD is targeting a mix of networking, data centers, broadcast, and the defense markets – all long-time and regular customers of FPGAs/adaptive SoCs and need the high-bandwidth chips.