[SI-LIST] Re: tools for really high speed

Lynne,

Why are you interested in such high frequency harmonics for board and 
package applications? 300GHz harmonics won't even go through the package 
inductance before they are attenuated to nothing! 

At frequencies above 50GHz, I think the real limitation is not imposed 
by the tools' abilities. It's more of a challenge to obtain accurate 
material and geometrical parameters to use with those tools.

For example, I don't know of any package/board material vendor that 
publishes dielectric and loss tangent data for those very high 
frequencies. You'd be lucky to obtain parameters for anything above 
10GHz! And even if you do, you should take them with a huge grain of 
salt! We have that problem now for frequencies <10GHz!

Another problem is the unforgiving nature of those very high 
frequencies. For example, the transverse and longitudinal variation of 
material/geometrical properties (anisotropy) you neglected at lower 
frequencies can no longer be neglected. Even the linearity assumption 
may not hold. Another challenge is to accurately capture all needed 
geometrical details such as surface roughness and other board/package 
tolerances. "Wavy" and "rough"  PCB/package layers can give rise to 
substantial losses at such high frequencies.

In short, at those very high frequencies, the burden is more on the user 
of the tools than the tools themselves. One good thing though:  no one 
will be able to prove that your interconnect parameters you extracted at 
300GHz are wrong since there is absolutely no way (as of yet) to 
validate the results through measurements :-)

Hassan.


lgreen wrote:

>Please reply offline: 
>
>Does anyone have any recommendations for extraction and simulation tools for
>data rates at 40 GHz (harmonics to 300 GHz)?
>
>Interconnects for both board and package need to be extracted with the field
>solver; S-parameter models would be acceptable.
>
>SI simulation could be done in an SI simulator or in a SPICE-type simulator.
>However, the signals are already known to violate the quasi-static
>assumption (higher order modes carry significant signal energy).
>
>- Lynne
>
>
>
>"IBIS training when you need it, where you need it."
>
>Dr. Lynne Green
>Green Streak Programs
>http://www.greenstreakprograms.com
>425-788-0412
>lgreen22@xxxxxxxxxxxxxx
>
>  
>


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