Hi Charles,
Having a trace shorted to ground at one end and leaving open at the
other end creates a quarter-wave resonator.
If for sake of example the propagation delay on the particular layer is
160ps/", 250mils has 40ps and the period at the quarter-wave resonance
is 4*40ps=160ps, which is around 6GHz. At that frequency (and
increasingly as we approach that frequency) the insertion loss,
reflection and crosstalk will be higher. Whether this creates a problem,
depends on the signaling speed and signaling budget.
Best regards,
Istvan Novak
Samtec
On 11/29/2021 1:55 PM, Charles Grasso wrote:
Hello all and I hope your Thanksgiving went well!
I am seeking some guidance on the effect (detrimental or otherwise) on
adding short (say 250mils) ground fingers in between high speed
differential
pairs at their source. i.e at the IC pin field. The ground finger only
has a via
at the entrance to the pin field and not at the final destination 250
mils away.
Does anyone know of (or have experience of ) any issues this may cause?
--
Charles Grasso
Dish Technologies
(c) 303-204-2974
(h) 303-317-5530
(e ) charles.gra...@dish.com
(e2) chasgra...@gmail.com
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