[SI-LIST] Re: Curve fitting of center-tapped inductor
- From: "Lars Juul" <write2larsj@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Tue, 18 Mar 2008 16:00:57 +0100
Good that you're attaching the lumped model of the inductor, that tends to
make the question easier to answer.
Could you shed some light on the fitting method and what tool you're using?
In network synthesis there are many ways of doing the realization of the
equivalent circuit, and some of them build on the idea of fixing some of the
lumped component values that you're relatively sure of, and fit the
remaining ones.
Do you have a rational function in the s-domain fitted to your s-parameters?
Assuming it's positive and real, then you pretty much have what you need to
make a manual realization, fixing some of the values you're pretty sure of.
That would be my take on it, any other suggestions?
Best regards,
Lars
2008/3/18, H B <neoflash2008@xxxxxxxxx>:
>
> Hi, folks:
>
> I come up with a strange thing when doing curve fitting for a differential
> center-tapped inductor.
>
> The original version of the inductor is a two-terminal differential
> inductor. I did curve fitting to find the equivalent circuit model. And the
> fitting seems good.
>
> The next step I added a center-tap and got a 3-port s-parameter from field
> solver. The problem is when I'm doing the curve fitting again. the mutual
> inductance in the circuit model was forced to zero by the fitting tool. The
> fitting seems OK but not as good as two-port one. The inductance and Q is ok
> but the s-parameter related with the third port are not well fitted.
>
> Any one ever experience same thing before? Any suggestions?
>
> Regards,
> Neoflash
>
> I've attached the link where the equivalent circuit model could be seen.
> http://www.designers-guide.org/Forum/YaBB.pl?num=1205764700
>
>
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