An engineering change order alters a nearly finished design. Changes range from replacing a cell by another with the same footprint, which leaves placement and routing alone, to restructuring logic, which changes function-level structure and needs equivalence checking. The more a change disturbs, the more must be re-verified. This topic covers each rung of that ladder with numbers.
Lesson | After it you can... |
|---|---|
Choose swaps by delay gained per leakage added. | |
Pick the number of buffers and compare with a layer change. | |
Restructure a logic cone using arrival times. | |
Say which checks each kind of change forces you to rerun. |
A swap keeps the netlist connectivity and the placement; a restructuring changes connectivity, so it needs new placement, new routing and a proof that function is unchanged.