Placement of decoupling capacitor on packages based on effective decoupling radius

A modeling method is presented based on the resonant cavity for the power/ground plane with decoupling capacitors in the high speed packages. Due to the high operating frequency of the package, decoupling capacitors behave locally. The algorithm for the effective decoupling radius of a decoupling capacitor is presented to characterize the limited decoupling region within which the impedance is smaller than the target impedance. Based on the decoupling radii of the decoupling capacitors, a method for the placement of the decoupling capacitors is presented to realize the decoupling task for the power distribution network in the packages.