Patrizio Vinciarelli
Analyst
Let me add a comment to that regarding thickness, right? So VR solutions with gearboxes and so on and so forth are quite thick, several millimeters, quite clumsy, thermally inept as opposed to that, very difficult to thermally manage, very costly, not [innately] reliable. There are IVRs, which are -- and are capable of up to about 1.5 amps per square millimeter current density. But they are challenging in other respects, which is in order to achieve the level of current density, they need to be supplied with 1.8-volt, which at high power levels implies a huge cost that need to get delivered at such a low voltage, very close to the point of load. And that was one of the points that Phil in his prepared remarks made. So the predicament for any customer seeking a VPD solution and looking at conventional approaches ranging from traditional VRs to IVRs, which is, in a way, a renewed attempt at that which Intel did with fiber many, many, many years ago, right, with very mixed results. They have relative to one another, certain advantages and disadvantages in particular. The VRs are typically powered nowadays from 5 or 6 volts. So power delivery to a VR is not quite as challenged as 1.8 volt. But then the VRs are thicker in terms of [indiscernible] solution, they must run at a much lower frequency, they've poor duty cycle. So that's Phil's point with respect to peak your poison. If you want to raise the intermediate bus voltage in order to get somewhat more efficient power distribution, your challenge in the voltage regulator, which works on an average in principle, is dividing a voltage by fundamentally mixing that voltage source with ground. And as you raise the level of voltage source as the upper voltage gets close to ground, you have to operate with a very low duty cycle, which is inefficient. Or in the alternative, you make the duty cycle efficient, 50% or so by going to an IVR, but then the problem is you can't efficiently feed the IVR. And fundamentally, the issue is that whether it's VR or IVRs, they don't have car game. And they insert a loss in the case of IVRs, which is upwards of 10%. And for that loss, you only get a factor or 2 car game which is nothing if the GPU, TPU needs thousands of amperes, right? I think it's been noted that the typical house power inlet is 150 amps. Obviously, it's a much higher voltage and that you can power whole house. But the challenges of distributing a 1,000 amp, or 1.8-volt are a significant handicap with respect to IVR. So they all have their trade-offs. They're all fundamentally constrained by the same laws of physics, which are lacking car game, make them somewhat handicap with respect to keeping up with processor road maps and processor current density requirements.