Well, that's interesting. I hadn't known that Intel was including a hardware RNG. In Linux, the kernel still gathers entropy:
The random number generator gathers environmental noise from device drivers and other sources into an entropy pool. The generator also keeps an estimate of the number of bits of noise in the entropy pool. From this entropy pool random numbers are created. (from man random)
Probably some reason for doing it. Maybe, for some purposes, only a few hundred kilobits of random numbers a second
isn't enough? I have no idea.
Looking at the simplified drawing (without knowing it was that) I thought, hey, I have inverter ICs, I could try that. But then comes the rub:
To keep the inverters in balance, we built a feedback loop into the new hardware. The circuitry in that loop performs some targeted fiddling until the two possible output values, 0 and 1, each occur roughly half the time.
And they're using IGFETS -- maybe I could subsitute MOSFETs, or something else, as long as I don't care about how fast the switching is. I don't have the knowledge to know whether there's some reason an insulated gate FET is needed here. And, even without the feedback loop, there's more to it than drawn -- VCC and ground, e.g.