Inductance extraction: L reduce with frequency?

Hi:

In some papers, they reported their extracted inductance. And the inductance decrease with the increase of frequency.

However, according to some other papers, the inductance increased. What's the difference in their used method of extraction?

I knows only attached one which L increase with F.

Thanks.

You can't see, that L decreases with frequency. It's just a method to calculate inductance from admittance measurements. The behaviour is simply from Y = 1/jωL.

I think the resonant will make Y = 0, then L will increase in Fres.

Let's take a finite-length coaxial cable as an example. The coax cable stretches from point A to point B. The coax consists of inner core and outer core which are both made of metal.

Now, let's agree that the inductance is associated with magnetic flux. Imagine there is a magnetic flux entering the inner core at point A and goes out at point B and enters the outer core at point B and goes out at point A and enters again the inner core at point A. Thus, we have a loop here.

At high frequency, skin-effect will occur, meaning the current will tend to approach the surface of the metal (of course exponentially), which is in this case getting closer to each other. The current inside the inner core will go outward and the current inside the outer core will go inward, causing the magnetic flux loop become smaller, hence, smaller inductance.

I hope this will explain.

regards,
wlcsp

I understand its physical origin.

However, any way to obtain this decreasing L curve from S/Y/Z parameters?

Will inductance decrease with frequency? I only know it increases with frequency.