An emerging technology can supply up to 3,000A to a single XPU.
The designers of the accelerator cards used to perform computationally-intensive tasks like artificial intelligence (AI) and high-performance computing (HPC) are running into a major problem—powering processors in the form of XPUs (CPUs, GPUs, NPUs, TPUs, etc.).
Today’s high-end XPUs can contain 100+ billion transistors (next generation devices that are coming onto the market, like NVIDIA’s B200, will contain 200+ billion transistors). Some existing 100+ billion transistor XPUs are rated at 1,000W. Assuming a core voltage of 1.0V, this translates to 1,000A. As transistor counts rise and core voltages fall, it is expected that accelerator cards consuming 1,500A to 3,000A will start to appear in the not-so-distant future.
If you look at an example of an existing accelerator card (https://bit.ly/4ijV5Gg), you’ll see that the XPU (an NVIDIA H100, in this case), sits in the center of the upper side of the board consuming less than 25% of the board’s real estate. The rest of the upper side of the board is filled with DC-DC converters accompanied by inductors. The lower side of the board is populated by thousands of capacitors that essentially act as a large, medium-speed energy storage unit.
This scenario, which is known as lateral (or horizontal) power delivery, results in up to 20% of the energy being lost (much of which is dissipated as heat, as indicated by the red ripples in the diagram). Furthermore, having the power converters and inductors pushed out to the edges of the board results in voltage ripple and noise. XPUs hate voltage ripple and noise, which drives the need for all the capacitors under the board.
One of the main factors underlying existing power solutions is the relatively slow responses of the DC-DC converters to changes in power demands from the XPU. This results in the need for the large inductors and high numbers of capacitors.
A company called Empower Semiconductor has developed a novel solution that addresses all these problems. Standard FinFET transistors can operate at gigahertz speeds but at low power. Empower has developed special FinFETs that can handle high voltage, high current, and high power at gigahertz speed. When combined with sophisticated control logic, silicon capacitors, and advanced high-frequency magnetic materials, the resulting Crescendo power converters can respond to changing power demands 1,000X faster than conventional technologies, all with very low noise.
The Crescendo presents everything in a custom package that is optimized for high frequency and power, and that is only 6mm x 7mm in area and around 1.5mm thick (by comparison, a US quarter is 1.75mm thick).
Since there is no longer any need for external capacitors and inductors, and since the Crescendo is so thin (which means it doesn’t impinge on adjacent cards), this means multiple Crescendos can be mounted on the bottom side of the board under the XPU to provide vertical power delivery.
An array of Crescendos mounted under the XPU can deliver up to 3,000A. Furthermore, the freed-up real estate on the front side of the board can now be used to accommodate additional components, such as DDR memory or even more XPUs.
Last, but certainly not least, in the case of hyperscale data centers, the power savings offered by vertical delivery over lateral delivery can equate to tens of megawatts!