What is SRF and where is it important?

SRF or self-resonant frequency is related to the parasitics of the component. An inductor has parasitic capaticance between its windings, a capacitor has series inductance due to the leads. The frequency at which the parasitic resonates with the component itself is the SRF.

The SRF is an important factor to have in mind when desiging, especially at RF. It can be used to your benefit. The capacitor has minimum impedance and inductance maximum impedance at its SRF, which is useful for decoupling and RF choke respectively (although the tolerance on the SRF is quite high). For any other application the operation frequency should be lower than the SRF.

Thank you very much.
So, for capacitor and inductor i must look for SRF when i design.

may i know how many time high should be the SRF form operating freq?