Modeling Dynamic Parasitic Loading Effects on Scan Network Timing Margins
Dynamic parasitic extraction during ATPG shift prevents false timing violations by accounting for state-dependent capacitance and power rail collapses.
Dynamic IR Drop
Voltage Deviation
Instantaneous voltage reductions occur across a power distribution network when large numbers of logic gates switch simultaneously. Engineers analyze dynamic ir drop to ensure that the supply voltage at the transistor level remains within the functional limits required for stable switching. This phenomenon accounts for the peak current demands that occur during a single clock cycle.
Power Analysis
Assessment begins by extracting the resistive and capacitive properties of the power and ground grids. When a clock edge triggers simultaneous transitions, the resulting dynamic ir drop is calculated by modeling the current draw of every active gate in the design. High frequency decoupling capacitors placed close to the device help to mitigate these transient spikes by providing local charge storage.
Sophisticated tools use vector-based activity files to pinpoint the exact time and location of the worst-case voltage sag. Failure to control these fluctuations leads to increased gate delays and potential logic errors.
Design Standards
Designers confirm compliance by running full-chip simulations under various switching scenarios. Results from a dynamic ir drop analysis identify regions of the grid that require additional metal width or more vias to handle the current density. The final report lists any instances where the local voltage falls below the minimum operating threshold specified for the semiconductor process.