Ferrite beads are lossy at the frequencies they are intended to filter so that the noise energy is dissipated as heat. App notes caution against blindly using them with capacitors lest a resonance peak make things worse than better. The app note says that the resonance peaks occurs if the LC resonant frequency between the bead and capacitor is below the crossover frequency of the bead (the frequency where resistance = reactance).
However, I was wondering then...what happens to this noise energy in an LC filter that uses an inductor? The noise energy in the inductor isn't be dissipated so where does it go? I always always kind of under the impression that the inductor stores the noise energy and releases it over time as a lower frequency than the original noise. Why is would dissipating it as heat, as is done in a ferrite bead, be more desirable?
And given that an inductor doesn't have a crossover frequency in it's operating range by design, LC filters using inductors would always suffer from resonant peaking, no? Why do I never see that issue discussed with LC filters that use inductors and only with LC filters that use ferrite beads?
However, I was wondering then...what happens to this noise energy in an LC filter that uses an inductor? The noise energy in the inductor isn't be dissipated so where does it go? I always always kind of under the impression that the inductor stores the noise energy and releases it over time as a lower frequency than the original noise. Why is would dissipating it as heat, as is done in a ferrite bead, be more desirable?
And given that an inductor doesn't have a crossover frequency in it's operating range by design, LC filters using inductors would always suffer from resonant peaking, no? Why do I never see that issue discussed with LC filters that use inductors and only with LC filters that use ferrite beads?