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

[Richard Wilbur]

On Tue, Aug 1, 2017 at 7:51 AM, mike.valk at gmail.com <mike.valk at gmail.com> wrote:
> 2017-08-01 12:29 GMT+02:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net>:
>>  there's a lot of other stuff in here which is really good, such as
>> making sure that lengths on each *layer* are matched, and that even
>> when turning corners the lengths are matched.  and matching just after
>> VIAs *not* before... damn
>
> Between via's the length should be matched right? Length mismatch
> should be solved as soon as possible to accommodate eddy-currents
> right?

Correct on both counts.

> Found a nice post from TI
> https://e2e.ti.com/blogs_/b/analogwire/archive/2015/06/10/differential-pairs-four-things-you-need-to-know-about-vias

Thanks for the link to an interesting article.  Thankfully we are well
below 10GHz on this interface and have 0 stub length as our signals
traverse the via all the way from top to bottom or vice versa.  We do
have the option to specifically adjust the antipad or keepout sizes
around our vias.  More discussion of this topic in the upcoming
section on impedance.