Hello,
Im working at dc biasing circuit which included RF chip inductor.
in the attached pic. L versus Frequency 0402HP Surface Mount Inductors. what are values (68nH,51nH,39nH,......) means? it appear out of the scale ?
thank you
Hi Alaa,
the values inside the graph are the nominal values of the inductors. So, if you buy an inductor with, say, 39 nH then the curve denoted 39 nH shows the typical behavior of your inductor, dependent on the frequency.
As you can see, the inductance is higher than the nominal value at low frequencies; it reaches the nominal value above 200 MHz.
While the vertical axis in the graph is denoted "inductance", I don't believe that the inductance is really increasing beyond 600 .. 1000 MHz. Rather, the impedance was measured, and the inductance was calculated using the equation L = sqrt(Z2 - R2) / (2 pi f), which is approximately true at frequencies well below the resonance frequency. The disproportionate increase of impedance (and hence of the now erroneously calculated inductance) at high frequencies is an indication that we are approaching the resonance frequency of the respective inductor.
nH = nano Henries. A Henry is a (very big) measure of inductance). It is the SI unit.
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