Routing

• Routing is the process of establishing physical connections between various components in the design.
• The different stages in routing are :-

• Global routing
• Track assignment
• Detail routing.

For routing, chip is divided into small blocks. These small blocks are called as routing bin. It is also known as g-cell. Each g-cell has a finite number of horizontal and vertical tracks.

• Global Routing: The first stage of routing is the global routing; it is done in the placement stage. In Global routing, the core area is divided into Global Routing Cells. In this stage only routing resources are allocated. Global routing assigns nets to specific GRC but it does not define the specific tracks for each of them.

• Track Assignment: Tracks will be assigning to all metal layers through each GRC. Routing will be done but pin to pin connection will not be there.

• Detail Routing: In Detail routing, the actual routing takes place the physical connections are made i. e. it will create actual metal and via connections.

The checks to be performed after routing are crosstalk analysis, DRC, LVS, ERC, EM, Antenna violations.