[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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