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

[Richard Wilbur]

On Mon, Dec 18, 2017 at 3:02 AM, Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:
> On Mon, Dec 18, 2017 at 7:02 AM, Richard Wilbur
> <richard.wilbur at gmail.com> wrote:
>> On Sun, Dec 17, 2017 at 11:34 PM, Luke Kenneth Casson Leighton
>> <lkcl at lkcl.net> wrote:
>>> On Mon, Dec 18, 2017 at 6:31 AM, Richard Wilbur
>>> <richard.wilbur at gmail.com> wrote:
>>>> 1.  Ground keepout under whole ESD component(s) on adjacent reference
>>>> ground plane (layer 2 for ESD on layer 1, layer 5 for ESD on layer 6),
>>>> ground fill on deeper layer (layer 3 for ESD on layer 1, layer 4 for
>>>> ESD on layer 6).  Ground fills connected as always using vias (some
>>>> probably already adjacent).
>
>>>
>>>  clear... except which one to actually deploy :)
>>
>> Well, I read about #2 in the TI High-Speed Layout but I like #1 better
>> because we have high-frequency signals in parallel on both sides of
>> the board and I'd feel better because I expect less cross-talk with
>> #1.  #1 is a hybrid where we double the distance to the reference
>> ground plane but still have ground shield between high-frequency
>> signals that would otherwise want to radiate/couple.
>
>  yehyeh, makes sense to me.  okay!  it's also much more straightforward.

After sleeping on it, I'd recommend making the new, deeper ground fill
slightly larger (~5mil? margin) than the ground keepout on the
original reference plane--as long as that's not too hard to
accomplish.