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

[Luke Kenneth Casson Leighton]

On Fri, Aug 18, 2017 at 5:51 PM, Richard Wilbur
<richard.wilbur at gmail.com> wrote:

> You bring up an interesting point:  what other current return paths are in the same vicinity?  I have not analyzed that in any detail.  At least there are no other lines from signal source to signal sink that I know of that cross the region of the board where the high-frequency HDMI signals are routed.  Also, to my knowledge we don't have segmented or restricted ground planes that would isolate regions with a higher-impedance reference.

 CEC etc. all follow roughly the same path, on layer 3 (separated by GND).

 i just noticed that SD0 runs round the back of the HDMI 1st set of
VIAS (with no GND separation) on layer 3 - i've removed the SATA power
(not being used) so i can shift them up a bit

 some GPIOs cross on layer 3 as well, just near the GND shielding near
those first vias...

 not much.

l.