[SI-LIST] Re: DesignCon presentations posted

Bill, I assumed that you meant lines where some of them would have 
impedances substantially different than 50 Ohms. The discontinuity 
between the test trace and the VNA is going to do rude things to S11. I 
think that only complicates the picture. About the only way we might get 
around that is if we have some relatively long, but really good low-loss 
cables then we can push the resulting reflection effects down to a 
frequency that is both easily identifiable and more or less out of the way.

Steve.

Bill Dempsey wrote:
> Hi Steve -- 
>
> Multiple lines, not multiple widths on the same line -- sorry if that was not 
> clear.  That was to eliminate etching variations and weave effects through 
> averaging of different traces on the same glass weave.
>
> The various line widths won't throw off the VNA... so with that clearer, does 
> my method work before getting into the resonator method you suggest?  
> (Removal of copper loss from insertion loss)
>
> Bill
> --- On Tue, 2/16/10, steve weir <weirsi@xxxxxxxxxx> wrote:
>
> From: steve weir <weirsi@xxxxxxxxxx>
> Subject: Re: [SI-LIST] Re: DesignCon presentations posted
> To: "Bill Dempsey" <cadcocat@xxxxxxxxx>
> Cc: si-list@xxxxxxxxxxxxx, Istvan.Novak@xxxxxxx
> Date: Tuesday, February 16, 2010, 9:04 PM
>
> Bill, varying line widths will throw the line impedance off and make VNA 
> operation problematic. I think a better answer is to build a resonator 
> structure and derive the loss from Q.
>
> Steve.
> 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
>> Â  <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
>>
>>
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>
> -- Steve Weir
> IPBLOX, LLC 150 N. Center St. #211
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Steve Weir
IPBLOX, LLC 
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Reno, NV  89501 
www.ipblox.com

(775) 299-4236 Business
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