<p>Embodiments of the present invention provide a system that controls noise in a power system that includes a power rail and a ground rail. The system includes a MOS transistor coupled in series with a decoupling capacitor between the power rail and the ground rail and an inductive packaging connection coupled to the power rail in parallel with the MOS transistor and the decoupling capacitor. The combination of MOS transistor, decoupling capacitor, and inductive packaging connection form a resonant circuit. During operation, the system determines if there is noise in a Vdd signal on the power rail. Based on the noise present in the Vdd signal, the system adjusts the impedance of the MOS transistor to reduce the noise in a frequency range near a frequency of interest (?interest) of the resonant circuit without causing an unnecessary increase in switching noise at other frequencies.</p>
