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A comment on Apple introduces M4 chip. Parent comment

Re:Apple introduces M4 chip by sroussey on Tuesday May 07, 2024 @01:09PM (#40288498)
SRAM has really stalled. I don’t think 5nm was much better than 7nm. On ever smaller nodes, sram will be taking up a larger and larger percent of the entire chip. But the cost is much higher on the smaller nodes even if the performance is not better.

I can see why AMD started putting the SRAM on top.

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Re:Apple introduces M4 chip by magicalhippo on Tuesday May 07, 2024 @01:39PM (#40288955)
It wasn't immediately clear to me why SRAM wouldn't scale like logic. This[1] article and this[2] paper sheds some light.

From what I can gather the key aspects are that decreased feature sizes lead to more variability between transistors, but also to less margin between on-state and off-state. Thus a kind of double-whammy. In logic circuits you're constantly overwriting with new values regardless of what was already there, so they're not as sensitive to this, while the entire point of a memory circuit is to reliably keep values around.

Alternate transistor designs such as FinFET, Gate-all-around and such can provide mitigation of some of this, say by reducing transistor-to-transistor variability by a factor, but can't get around root issue.

[1]: https://semiengineering.com/sram-scaling-issues-and-what-com...

[2]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9416021/

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