[SI-LIST] Re: DesignCon presentations posted

  • From: Istvan Novak <istvan.novak@xxxxxxx>
  • To: Bill Dempsey <cadcocat@xxxxxxxxx>
  • Date: Tue, 16 Feb 2010 23:02:32 -0500

Hi Bill,

Yes, all those things you mention are doable, but the challenge is that 
eventually we need a trusted model to fit to, because beyond a few 
hundred MHz there is no direct way to measure the contributing factors 
separately. AND the more cross-correlation we do (for instance different 
line trace length, different line widths, etc) the more we rely on the 
elusive assumption that everything else stays the same except the single 
parameter we intend to change.


Istvan Novak

Bill Dempsey wrote:
> <second posting...apologies>
> Hi Istvan,
> I just read the DesignCon paper on the loss tangent measurement and had a 
> question with regards to other possible techniques to measure Df (and 
> similarly Dk).
> Previously you built a stripline test board for measuring glass weave 
> effect.  The cool thing about this board was that you launched from "inside" 
> the board and minimized the effects of the launch structure.   Couldn't you 
> build a similar test board with various copper line widths and measure 
> insertion loss on a VNA?  Once you have the insertion loss, couldn't you 
> then subtract out the Rdc+Rac component from the overall insertion loss to 
> give you a loss curve from which you could derive Df?  Use the various line 
> widths to minimize any weave effect.
> Using this same board, can you not look at group delay to also measure the Dk 
> over frequency?
> I know your paper talks about cured and uncured resin variations but in the 
> end, isn't it just the cured value we need?  Most tools don't address a 
> frequency dependent Df/Dk at this time so what do we do once we get a 
> frequency dependent Dk/Df anyway? I'm curious to see how others are 
> addressing this issue and how much their lab measurements have been off from 
> simulations.
> And I'd like to see some posts from tool vendors who are addressing the 
> frequency dependence of these values.
> Regards,
> Bill
> From: istvan Novak <Istvan.Novak@xxxxxxx>
> To: SI-List
>  <si-list@xxxxxxxxxxxxx>
> Sent: Mon, February 15, 2010 10:52:42 PM
> Subject: [SI-LIST] DesignCon presentations posted
> FYI:
> For those of you who could not make it to DesignCon, the Oracle-SUN 
> presentations are posted at http://www.electrical-integrity.com/
> For the three Best Paper Award winner presentations, both the written 
> materials and the slides are posted:
> “Introduction and Comparison of an Alternate Methodology for Measuring 
> Loss Tangent of PCB Laminates�
> “Additional Trace Losses due to Glass-Weave Periodic Loading�
> “Accuracy Improvements of PDN Impedance Measurements in the Low to 
> Middle Frequency Range�
> Also posted are the slides for the panel discussion "Making Sense out of 
> Dielectric Loss Numbers, Specifications and Test Methods"
> Regards,
> Istvan Novak
> Oracle-SUN

To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List technical documents are available at:

List archives are viewable at:     
Old (prior to June 6, 2001) list archives are viewable at:

Other related posts: