David Curtis wrote:
>
> Hi there,
>
> Can anyone comment on the validity of a stripline Zo calculation when
> the layer in question resides between a plane and another signal layer
> and then a plane, instead of between two planes?  The intent of the
> designer was to ignore the adjacent signal layer. Fab guys: is this
> acceptable when you have to meet a certain spec?
>
> Thanks,
>
> Dave
>
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Hi Dave,

   That configuration sounds a heck of a lot like me to a dual stripline
which is a different calculation.

   The additional signal layer will have an effect on the impedance of
the desired signal layer. If the dielectrics between each circuit layer
to ground are even you will definitely want to use a dual stripline
calculation. If the dielectrics between each circuit layer to ground are
not equal you will need to use an offset dual stripline calculation.

                                                Regards,
                                            David G. Pacheco

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