Modern integrated circuits require a power delivery network capable of supplying large and rapidly changing currents while maintaining a stable local supply voltage. On-chip power grids use multiple metal layers, wide conductors, dense vias, and distributed supply connections to reduce resistance and support high current density. IR drop results from resistive current flow, while package and board inductance converts rapid current changes into L di/dt noise. Distributed decoupling capacitance supplies transient current close to switching circuits and reduces the high-frequency current demanded from package connections. Power delivery behavior is strongly frequency dependent. Board, package, and on-chip capacitors operate over different frequency ranges because capacitance, ESR, ESL, and interconnect inductance determine effective impedance. Power-network resonances can create large impedance peaks, while abrupt changes in chip activity can generate multiple supply droops as current support transfers from on-chip capacitance to package capacitance, board capacitance, and eventually the voltage regulator. Lumped and distributed network models provide complementary views of this beha...