Design Exchange Format (DEF) – SiliconVLSI

VLSI (Very Large Scale Integration) design uses the DEF (Design Exchange Format) file format to express the actual layout of a chip. It includes details on the placement, dimensions, and interconnections of each component on the chip. After the physical layout has been developed and the logical design (such as RTL or netlist) has been verified, DEF files are often utilized in the last phases of chip design.

Data Exchange Format(DEF) Contains the following Information.

HEADER: Contains information about the DEF file version and the units used in the file.

COMPONENTS: Lists all the components on the chip, including their name, type, and location.

PINS: Lists all the pins on the components, including their name and location.

NETS: Lists all the connections (nets) on the chip, including the names of the pins they connect and the components they connect to.

ROUTES: Lists the routing information of the chip including the layer, width, and shape of the route.

Various VLSI design tools, including place and route tools, verification tools, and DRC/LVS (Design rule check/Layout vs Schematic) tools, among others, may import and export data using DEF files. The majority of EDA (Electronic Design Automation) tools employ the DEF file, one of the industry standard file formats.

Data Exchange Format example in VLSI

VERSION 5.8 ;
DIVIDERCHAR “/” ;
BUSBITCHARS “[]” ;
DESIGN TEST_DESIGN ;
UNITS DISTANCE MICRONS 1000 ;

COMPONENTS 5 ;
– NAMETYPE “INV” ;
– “inv1”
– “inv2”
– “inv3”
– “inv4”
– “inv5” ;

PINS 10 ;
– NET “VCC” DIRECTION INPUT ;
– “inv1/A”
– “inv2/A”
– “inv3/A”
– “inv4/A”
– “inv5/A” ;
– NET “GND” DIRECTION INPUT ;
– “inv1/Z”
– “inv2/Z”
– “inv3/Z”
– “inv4/Z”
– “inv5/Z” ;

NETS 2 ;
– NET “VCC” ;
– NET “GND” ;

END DESIGN