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 Parasitic Extraction
Parameter Calculation
Computational processes calculate the effective resistance, capacitance, and inductance of interconnects by considering the instantaneous state of neighboring nets. Using dynamic parasitic extraction allows for an accurate representation of circuit behavior compared to static models that assume constant coupling values. This method is used for high speed designs where the switching of one wire alters the electrical characteristics of its neighbors.
Extraction Mechanism
Field solvers analyze the three-dimensional geometry of the traces and the dielectric properties of the surrounding materials to generate a netlist. During dynamic parasitic extraction, the tool accounts for the feedback effects and the relative timing of transitions on adjacent lines. Designers rely on these results to perform precise timing and power simulations that account for real-world interactions.
The software produces a detailed model of the parasitics that is then back-annotated into the circuit simulation environment. Accurate modeling of these transient properties is required for circuits operating above the gigahertz range.
Verification Integrity
Reliability of the final timing sign-off depends on the accuracy of these extracted values. If the dynamic parasitic extraction process underestimates the coupling capacitance, the circuit may fail to meet its timing requirements in the physical hardware. Regular calibration against known test structures ensures that the extraction engine remains consistent with the manufacturing process.