Ask HN: In modern CPUs how many μs to flip a NAND (or other) logic gate? - josh-wrale
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nicholas73
For logic gates there is a "setup" and "hold" time (logic level prior to gate
flip, then hold that level) for an operation to be successfully performed and
transmitted to the next stage. It should be in the chip's datasheet (if you
wanted a precise and specific number). If you don't care about logic
transmission and just want "flip" then look at the rise/fall time.

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samfisher83
It depends on PVT. Process, Voltage, and Temperature. When chips are being
synthesized all this is characterized for each logic cell like and gates, flip
flops, etc. They are in .lib files that is sent into the synthesis tools. If
you can get one of those files it will tell you all the numbers.

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Majster
Can you be a bit more specific? You mean how long a NAND gates takes to
"execute" a NAND operation? It's somewhere around 20 nano seconds.

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alain94040
20ns corresponds to 50 MHz. Recent CPUs run at over 1 GHz, so 20ns is
completely off. And the clock frequency includes many gates on its critical
path.

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josh-wrale
I suspect it's actually better measured in femtosceonds, but either way is
good.

