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Hello Helmut:

Thanks so much. I downloaded your model and tried in my circuit model. I think it worked. Of course the expression needs to be refined.
So I take it that for inductance, if it's L=4u*(freq/2.5e6)^(-0.5),
then when I use G2 (voltage controlled current),
I should define the value as Laplace=1/(S*L),
is it correct?
In a similar way, capacitance can be defined as well.

Best regards

Summer

--- In LTspice@..., "Helmut" <helmutsennewald@> wrote:

--- In LTspice@..., "coldcolor0317" <coldcolor0317@> wrote:

Vlad:

Thanks so much for the response. I do want to simulate an AC analysis from 100Hz to 10MHz. The coil is essentially an inductor with a certain value. There's AC resistance too. SO R is increasing with freq, and L is decreasing with freq. I need to model this behavior.
Would you please specify more on how to do it?

Many thanks,

Summer

Hello Summer,

The formula with FREQ doesn't work. You should use a Laplace
function. Below is an example using a G-source.

Laplace=1/(0.95*(s/(2*pi*2.5e6))**0.3+0.1)

I have uploaded an example.

Files > Temp > freq_dep_res.asc

Best regards,
Helmut

--- In LTspice@..., "imbvlad" <imbvlad@> wrote:

Hello

R=0.95*(FREQ/2.5e6)^(0.3)+0.1.

This is the way to do it in LTspice, too, unless you want an .AC analysis. If "freq" is some external source, v(freq), it will work. You may need to add curled braces, though.


Good luck,
Vlad