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