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@gmail.com mike.valk@gmail.com wrote:
2017-08-09 15:23 GMT+02:00 Luke Kenneth Casson Leighton lkcl@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.