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You're basically right. Nobody doing actual chip design cares about process nm numbers. Process selection done right is a fairly tedious comparison of dynamic
by variaga 6y ago
You're basically right. Nobody doing actual chip design cares about process nm numbers. Process selection done right is a fairly tedious comparison of dynamic power consumption, static power consumption, achievable operating frequencies, wafer cost, SRAM density, IP availability, process maturity/yeild, fab capacity/ availability and about a dozen other factors.
There will be a large-ish excel spreadsheet somewhere to do the comparison.
The nm number is for press releases and non-technical investors.
- imtringued 6y agoIt's basically a version number.
- variaga 6y agoYes, that's a good analogy, although the nm number by itself isn't the full version e.g for 28nm alone, TSMC had 28HP, 28HPL, 28HPM, 28HPC and 28HPC+ variants, of which only HPM and HPC (but not HPC+!) are at all compatible. 28HPC+ and 28HP have very different performance, even if they're both "28nm". And if you really want to specify a process you also need to know the metal stack (lots of options there), Vt selection(s) (most processes have 2-5 options) & high-voltage device support option.