I have fabricate spiral inductor and measure the inductance value using LCR meter (Agilent 20-1MHz). But I notice the measured inductance value is not same with my simulation (I use CST to simulate planar spiral inductor). What is the best frequency range to accurately measure the inductor? Is it because I measure at low frequency (below 1 MHz) then it caused the measurement is not accurate?
In general, if your LCR meter allows it, measure the impedance ( and L value) at the application frequency if you can.
In the simplest description, the inductance will have a parallel capacitance because of the way it is built. This becomes more significant at higher frequencies, so the "inductance" varies with frequency, up to the resonant frequency, past which it behaves like a capacitor.
Norliana,
Your planar spiral inductor has parasitic resistance and capacitance as noted by Malcolm. From my point of view, you have to choose the frequency such that wL>> r where w is the frequency, L is the inductance value and r its self resistance.
On the other side you must choose the frequency to much smaller than the the self resonance frequency w0.
In fact L is independent of frequency but the problem is with the accuracy of measurement of very small inducers.
Best wishes
Thank You very much for all the responses. I think I should redesign my inductor since r value (parasitic) value is high.
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