Level shifter
Beginner
A small part that acts like a translator for a signal passing between two areas that run at different power levels.
Novice
A small cell placed on a signal that crosses from logic running at one supply voltage to logic running at another. Without it, a low-voltage signal may not switch a higher-voltage receiver cleanly.
Expert
Required where a low-voltage domain drives a high-voltage one; otherwise the receiver can suffer short-circuit current and leakage. Specified in the UPF, placed near the domain boundary and powered from one or both supplies, so the floorplan reserves room for them.
Explained in Floorplanning (Design Flow).
See also: Voltage area (power-domain area), isolation cell.