Timing-driven placement

Timing-driven placement. Some nets are on the critical path (drawn bold) and must stay under a tight delay budget, which here means a short wire. Placing for raw wirelength is not enough: the critical nets have to be short even if it crowds other cells.

The cells start scattered, so the critical nets are long and red.

• Timing closes - pull the cells on each bold critical net tightly together (and next to its pin) so its wire comes under budget.
• Legality - cells inside the die, not overlapping.

Close every critical net, then Submit design. Shorter wire scores higher.