SRF (Self -resonant frequency)

An inductor has low distributed capacitance between terminal electrodes or the turns of a wire-wound conductor, and its inductance with such distributed capacitance resonates at a certain frequency. This frequency is called the self-resonant frequency, and the inductor does not function as an inductor beyond the self-resonant frequency. At the SRF the impedance becomes high and the inductor can be used as a choke to attenuate signals near at the SRF.

When selecting an inductor for high frequency circuits and modules, it is not enough to simply consider the required inductance. You need to take into account that the self-resonant frequency must be sufficiently higher than the usage frequency.

Digi-key has a filter for the fixed inductors where you can pick the self-resonant frequency. This will help narrow down your search if SRF is a factor you need to worry about.

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For other information on how to filter and find parts on our website you can read this article: How to Use Digi-Key’s Part Search More Efficiently or the Part search help.