Voltage area (power-domain area)
Beginner
A fenced-off part of a chip that can run on less power, or be switched off, apart from the rest.
Novice
A fenced region of the chip for one power domain: a group of logic that runs at its own supply voltage or can be switched off on its own. The domain’s cells must sit inside the fence, and its power wiring connects to that domain’s supply.
Expert
Implemented as an exclusive region (OpenROAD set_domain_area; a FENCE region in DEF). Its boundary is where level shifters and isolation cells go, and a domain that switches off also needs room for its power-switch cells.
Explained in Floorplanning (Design Flow).
See also: UPF, Level shifter, isolation cell.