Select 30nm CMOS processes already had fT (frequency at which transistor no longer has gain) of 300GHz, so the component-level limits are probably flirting with THz by now. Of course, you need to knock off an order of magnitude to build useful comparators/etc out of those, and that gives you... 100GHz, right about what we see on those high speed SerDes :)
One more thing: CMOS historically wasn't the fastest logic family. Bipolar ECL was faster, but it burned a ton of idle current, so it ran into power limitation long before CMOS.
In either case, thermal limits prevent you from using these speeds across the whole chip, but just because your thermal budget can't afford 10,000,000,000 speed demons doesn't mean it can't afford 1000 of them in a few SerDes :)
But yeah, decades of Moore's law have not gone to waste, and those discrete logic chips are frozen in time. It's a neat reminder of how far we have come!
One more thing: CMOS historically wasn't the fastest logic family. Bipolar ECL was faster, but it burned a ton of idle current, so it ran into power limitation long before CMOS.
In either case, thermal limits prevent you from using these speeds across the whole chip, but just because your thermal budget can't afford 10,000,000,000 speed demons doesn't mean it can't afford 1000 of them in a few SerDes :)
But yeah, decades of Moore's law have not gone to waste, and those discrete logic chips are frozen in time. It's a neat reminder of how far we have come!