[SI-LIST] Re: SwItChING FREQUENCY IN SPECCTRA QUEST

Thanks Bill.

 The simulation failed to deliver the results I
had expected.

I was trying to do some post route simulations to verify signal integrity
and
timing for busses particularly.  The simulation either failed to deliver the
expected results or the results
were all NAs. Usually the resulted signal is nonmonotonic.

regards



----- Original Message ----- 
From: "Bill Wurst" <billw@xxxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Friday, April 22, 2005 8:45 PM
Subject: [SI-LIST] Re: SwItChING FREQUENCY IN SPECCTRA QUEST


> Race,
>
> Your best bet is to get the model from the manufacturer.  However, if
> the manufacturer's datasheet contains a plot of Z vs. frequency, then
> you have enough information to develop your own model.  Ferrite beads
> generally follow the impedance of a parallel LRC circuit.  If a
> single-stage parallel LRC gets you reasonably close to the published Z
> vs. f curve, then you're done.  If not, try adding additional parallel
> LRC stages in series with the original, adjusting the impedance of each
> to give the desired result.  Admittedly, this is a somewhat heuristic
> approach, but I have used it before with success.  Regarding the
> switching frequency, you will want to make sure that your model
> accurately represents the impedance of the bead from the fundamental of
> the switching frequency to the highest harmonic of interest, which will
> depend upon your application.
>
> When you say that the simulation failed, was it that SPICE failed to
> execute, or was it that the simulation failed to deliver the results you
> had expected?
>
>     -Bill
>
>
>       /************************************
>      /        billw@xxxxxxxxxxx /
>     / /
>    / Advanced Electronic Concepts, LLC /
>   /           www.aec-lab.com       /
>   ************************************
>
> ==============================
> race wrote:
>
> >>hello to all,
> >>
> >>GOod afternoon!
> >>
> >>I am an SI trainee. I was tasked to do some simulations on one of our
> >>boards.
> >>
> >>Im looking for a ferrite bead espice model from murata;
> >>PART NAME: BGLM18AG121SN1D. I have tried sending inquiries to murata but
> >>
> >>
> >got
> >
> >
> >>no reply regarding on the espice model.
> >>I need the model for my bus simulations.
> >>I have tried replacing the bead with a 100 ohm resistor at 100 MHz but
the
> >>simulation failed. And
> >>by the way, how will the switching frequency affect my simulations?
> >>
> >>Could someone help me on this.
> >>
> >>ANy help is really appreciated.
> >>regards,
> >>race
> >>
> >>
> >>
> >>
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