Stability-dependent spare cell insertion

摘要

Spare cells are placed in an IC design using stability values associated with logic cones of the design. A desired spare cell utilization rate is assigned to a cone based on its stability value, and an actual spare cell utilization rate for the cone bounding box is calculated. If the actual utilization rate is less than the desired utilization rate, additional spare cells are inserted as needed to attain the desired utilization rate. The stability value is provided by a logic or circuit designer, or derived from historical information regarding the logic cone in a previous design iteration. Spare cells are placed for each logic cone in the design until a global spare cell utilization target is exceeded. The spare cell placement method can be an integrated part of a placement directed synthesis which is followed by early mode padding and design routing.