Re: [BP] SDD21 Concern

["Stephen D. Anderson" <Steve.Anderson@xxxxxxxxxx>]

 

    Joel, all:

    I think that people focussed on the very high frequency region of my proposed SDD21 magnitude.  This isn't what I intended.  I was focussing mainly on the region from 50 MHz to 5 GHz.  However, when I saw that the equation coefficients I picked created a curve that was below most of the measurements we had, I stopped and didn't go any further.

    John D'Ambrosia pointed out to us that this doesn't allow for an upper-layer ATCA QuadRoute channel, which happens to have a null in the region of 10 GHz.  (My guess is that it probably doesn't allow for any upper-layer channel that doesn't use backdrilling.)

    We (Xilinx) think that most signaling methods are probably not very dependent on what happens at 10 GHz.  So, in the interest of resolving this, Brian Seemann and I are re-evaluating Xilinx' proposed curve.

    One question I would ask:  If the curve is to be formulated primarily on the basis of whether or not backdrilling is done, then why have we paid so much attention to Dk,Df?  Whether the curve moves up or down by a dB is probably 90% dependent on backdrilling and 10% on material.

    Regards,

    Steve A.
 

Joel Goergen wrote:

Hi Everyone.

I'm really concerned that no one has agreed or disagreed with any of my personal observations on the SDD21 mask.  I'm hoping everyone received what was sent.

Further, I was hoping for discussion and I don't see any at all.

????
-joel

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