Inductors and capacitors are often described in terms of the (1) inductance/capacitance
at a particular frequency, (2) quality factor and (3) self-resonant frequency (SRF). The
inductance/capacitance varies due to the non-ideal behavior of the component. For instance,
the intrinsic inductance may vary with frequency due to non-uniform current
ow (current
crowding) at high frequencies. More prominently, though, the inductance/capacitance varies
due to the complex parasitics associated with the component. Instead of specifying the
equivalent circuit model, many manufacturers simply specify these two or three numbers. If
the components are used well below their self-resonant frequency, these three numbers may
be sucient to characterize the structure.