Switching regulator with integrated resonant circuit for ripple filtering

摘要

A switching regulator IC contains both switching regulator circuitry and an inductor and a capacitor connected in parallel to form a resonant circuit having an associated notch filter frequency response arranged such that, when connected to receive the regulated output voltage, the resonant circuit attenuates the ripple component. This is accomplished by matching the resonant notch to the ripple's fundamental frequency, either manually or automatically. In addition, the resonant circuit's inductor and capacitor can act in concert with decoupling capacitors coupled to the load to form a low pass filter which attenuates harmonics of the ripple's fundamental frequency.

主权项

1. A switching regulator integrated circuit (IC), comprising:
switching regulator circuitry arranged to produce an output which, when coupled to a storage inductor and storage capacitor, form a switching voltage regulator which produces an output voltage when in use, said output voltage including a ripple component having an associated fundamental frequency that varies with a frequency of a clock signal of the switching regulator circuitry; an inductor and a capacitor connected in parallel to form a resonant circuit having an associated notch filter frequency response that includes a resonant notch, said switching regulator circuitry and said resonant circuit housed within a common IC package; means for automatically trimming said clock signal frequency such that the resonant notch in said notch filter frequency response and said fundamental frequency are matched; and said switching voltage regulator and said resonant circuit arranged such that, when connected to receive said output voltage, said resonant circuit attenuates said ripple component;means for automatically trimming said clock signal frequency such that the resonant notch in said notch filter frequency response and said fundamental frequency are matched.