[Arm-netbook] HDMI High-Frequency Layout: Recommendations--Taper

[Luke Kenneth Casson Leighton]

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On Tue, Dec 12, 2017 at 2:54 PM, mike.valk at gmail.com
<mike.valk at gmail.com> wrote:

> We'll I'm not convinced on the reflections in inter pair matching. But
> indeed my "linear" might not be the best and results in unequal
> impedance transitions and thus in signal degradation. But you can stil
> do gradual corners. See the "transitioned" attachment.

 yes.  the issue i have with the 45-degree thing is that it has to be
staggered (you can't make the transitions on *exactly* the same
X-distance along the axis because the pairs, during the 45 degree
turn, would actually come *too close* by a factor of pow(2,0.5) *
5mil.

 a non-45-degree variant - exactly as you draw - would not have that
same problem.  *but*.... at the same time, 8 steps would not be
anything like enough, because of the risk of inaccuracies in the
distance between the tracks, perhaps going to 4.95mil separation at
the exact point where each track turns.  all a pain.

 and that's why i said that 100s of such steps would be needed...
which i'm not going to do right now, as i would need the actual
formulae from the 1956 paper as opposed to richard's hand-calculated 8
steps.

> But without a, 3d, simulation or a real world test this is all very theoretical.

 the theory - which has had quite some time to mature and be
demonstrated to be accurate both in complex electrical simulations
(papers doing this were referenced on arxiv.org in the original
message that richard sent a few months back) and the real world - has
matured over the past 60 years and that's why i'm trusting richard's
assessment.

l.