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

[Richard Wilbur]

On Wed, Aug 23, 2017 at 5:27 AM, Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
> damn.  i just noticed:  the via transition here is at 90 degrees.
> i've been switching off except 1 layer at a time so didn't notice.
> arse.
>
> i'll need to shift all but the TX2 via set down a fixed amount so i
> can get a second wiggle in the right-hand one one layer 1, to make the
> track come in to the top right corner (1 o clock). rather than as they
> do now: from right side (3 o clock).

Not necessarily bad on the same scale as you might think.  Our board
is ~47mil thick while the copper is ~1mil thick, so when a signal
plunges into a via from top to bottom it's already making a 90 degree
turn into and out of the via.

I'm not criticizing your attempt to straighten out some corners we
have control over in the signal path, just pointing out that vias
themselves present the signal with a couple 90 degree turns.