What is LEF?

LEF (Library Exchange Format) is an open, ASCII-based format used to describe the physical characteristics of standard cells, macro cells, and intellectual property (IP) blocks in integrated circuit design. It contains information about cell sizes, pin locations, metal layers, and via definitions. LEF files are essential for place and route tools to properly arrange and connect these cells during the physical design process of an integrated circuit. It is often paired with DEF (Design Exchange Format) to represent the complete layout.