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

Hrvoje Lasic lasich at gmail.com
Thu Aug 10 09:14:54 BST 2017

the case for GND around differential pairs cant hurt, maybe even can help.
But is it better to have GND in plane below that actually is doing same
things? If there is no clear path for signal to go back then I guess put
GND in parallel is good but if you have clean GND below than make it
somehow redundant. Or am I wrong? I am discussing these because most
probably there is tight space even without GND lines...

On 10 August 2017 at 10:01, mike.valk at gmail.com <mike.valk at gmail.com> wrote:

> 2017-08-09 15:23 GMT+02:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net>:
> > next set...
> >
> GND shielding parallel to the differentials is interrupted quite
> often. Those GND tracks act as shields, for emission and reception.
> I'd try to put as much parallel GND as possible.
> And trace the parallel GND around the via's, see attachment.
> Make sure the'res as much solid GND on the layer above and below the
> traces, again shielding.
> Also I'd personally not use curved wriggles. HF signals travel in a
> straight direction. With curves they start diffracting and start
> bouncing cross each other and might start to radiate or echo back. But
> I see that the community is divided on that stance.
> If tight for space you can use 90% corners with a chamfered outer
> edge. I suppose the chamfer acts like a mirror.

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