Transistor Count vs. Die Size vs. Process Technology

[imported_Ged]

My real question is 'does transistor count scale linearly with respect to die size?'

For instance: if I had a 100mm^2 die area on 130 nm process with n number of transistors, I could have Xn the number of transistors with the same 100mm^2 die area on a 90 nm process?

I understand that scaling like this isn't exact, but there seems to be a general way to figure it out.

The reason why I ask is because of a thread from the Video portion of the forums.

NVIDIA's NV40 GPU is said to contain roughly 223 million transistors and have roughly a 300mm^2 die size on, I believe, IBM's 130 nm process.

NVIDIA's G70 GPU is said to contain roughly 304 million transistors and have roughly a 300mm^2 die size on TSMC's 110 nm process.

If NVIDIA were to use a 90 nm process, how many more transistors could NVIDIA add to their GPU assuming the same 300mm^2 die size?

Thanks in advance.

 

[Calin]

Transistor count would scale with the square of linear dimension, or proportional with the area.
Transistor count would increase with the square of the decrease in "process technology" (if a 100mm^2 die made in 180nm process has 20 millions transistors, a 100mm^2 die made on a 90nm process will have 4 times as much (80 millions), and an older 100mm^2 die in a process of 540nm would have a ninth of 20 millions transistors).
This is assuming the core (silicon) has the same number of layers, if you use more layers you can increase the transistor count on the same area. However, this is a problem because Si isn't so good at transferring heat, and you will have pockets very hot in an otherwise cool processor (too much power density).

Now about your question, the number of transistors would be increased by the inverse square of the process.
Taking it in another way, number of transistors multiplied by their area must be proportional to the surface:
223 (millions pieces) * 130 (nm) * 130 (nm) = 3768700 (something)
304 (millions pieces) * 110 (nm) * 110 (nm) = 3678400 (something)
(it is a 3% variation, I feel this can be ignored for our teaching demonstration)
For a 90nm process, you'd have transistor count around 3700000 / 90 / 90, or some 450 millions

 

[iwantanewcomputer]

F that shyt

 

[imported_Ged]

Appreciate your reply Calin. Thanks.

 

[Calin]

Glad to help