[SI-LIST] Re: mode conversion myth
- From: liuluping 41830 <liuluping@xxxxxxxxxx>
- To: shlepnev@xxxxxxxxxxxxx
- Date: Wed, 07 Jan 2009 15:38:01 +0800
Yuriy :
Yes,the compensation method in the papaer is not perfect.
Just as Istvan said "None of our actual designs is perfect" :(
Best Regards,
LIU Luping
Msg: #5 in digest
From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: ??:RE: Re: mode conversion myth
Date: Mon, 5 Jan 2009 10:48:03 -0800
Liu,
Thank you for the reference.
The paper may be helpful. Though it requires some caution in interpreting
the results. The geometries selected for the experiments are oversized (1.75
mm strips with 0.75 mm separation on 1.5 mm dielectric). The results may be
appropriately scaled to a normal PCB size, though a new analysis would be
much easier to do. Considering the compensation with the capacitors at the
bend, the paper shows that the mode transformation can be reduced indeed,
but it leads to a larger differential return loss. At least, graphs on Fig.
13 can be interpreted in that way. Though, it is hard to do such analysis
because of the differential line impedance was selected to be around 94 Ohm,
that causes reflection from the ports with 100 Ohm differential termination
and obfuscates the effects of the capacitance on the transformation and on
the return loss. Note that we did similar investigation for traces with
dimensions more typical for PCB interconnects and the conclusion was to
stick with the structures with lower differential return loss and do
compensation with the complimentary symmetrical bends.
Best regards,
Yuriy Shlepnev
www.simberian.com
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