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

Luke Kenneth Casson Leighton lkcl at lkcl.net
Fri Jan 5 07:44:17 GMT 2018

On Fri, Jan 5, 2018 at 7:32 AM, Richard Wilbur <richard.wilbur at gmail.com> wrote:

> Looks like you already addressed this in the latest gerbers!


> Any
> chance we could use another trace to even up the little dimples that
> are left in the edge facing the differential pairs?

 always best to screenshot / arrow-mark it, richard.  round-trip
delays getting critical here, we're up to 5th january already.
attached green arrows, i am guessing you mean, i remember you said
that causes... something-or-other... capacitance-related?

 there's a few more like that back at the source diff-pair vias, i'll
think about whether to drop a plain square keepout in place (to
preserve 15mil) or a straight manual track.  track would cut clearance
to around 12mil.  thoughts?

> I glanced at parts of the rest of the board but it would be much more
> straightforward with the schematics.

 not so concerned about the rest of the board, it's mainly the HDMI.
PDF version of schematics should be here

> Do you have a way to compare
> changes with previous versions of the board to see if PADS did
> anything surprising behind your back?

 the only way would be visual pdf diffs, and i've made several minor
changes as well that would show up and need to be reviewed, one by
one, and eliminated.  i've found it's easier just to go over the board
making minor tweaks, because each time i do so i find one more "little
thing" such as a place where there's a capacitor that doesn't have a
nearby GND via and so on.
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