Work out voltage droop instantly with clear inputs, formula shown and shareable results.
Supply droop has two parts: L di/dt from the power delivery inductance and I x Z from the resistive impedance of the decoupling network. A 25 A step in 2 ns through 120 pH gives 1.5 V of inductive droop unless on-die capacitance supplies the transient locally.
Voltage droop
droop = L x di/dt + I x Z_decap
Because L di/dt scales inversely with rise time. A nanosecond-scale current step sees inductance that is invisible at DC.
On-die capacitance, which has negligible inductance to the load. Package and board capacitors handle progressively slower droop events.