The current duration is 20 years.
But companies with sophisticated IP lawyers, like FPGA vendors, can create "evergreen" patents by tweaking existing ones to last 100 years or more.
Also, small companies generally cannot afford patent litigation, so most fold after just receiving a letter.
Hollywood is located in LA because East Coast companies didn't want to pay Edison patent royalties. Moving to another state is less likely to work these days.
The laser patent killed commercial laser products until it expired, since nobody wanted to pay the 4% or 5% royalty. (I'm guessing that it wasn't that one royalty that was the concern, but the likely additional demands that would come out of the woodwork.)
Same thing with the Wright Brothers airplane patents. It took war for the Wright Brothers and Curtis to work together, which is why Europe got so far ahead of the US in aviation at the time.
Would these patents apply in the EU?
I suspect that US evergreen patents would be annoying to the EU if pointed out, though.
I don't really get the desire to make your own FPGAs though. They will probably end up being slower and more expensive. It makes more sense to me to work on toolchain software.