RE: [SI-LIST] : Crosshatched ground planes

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From: Mark Gill (gillmf@nortelnetworks.com)
Date: Thu Jun 22 2000 - 03:42:19 PDT


Martyn -

I saw something along these lines (but not completely crosshatched) in a
paper from Design Supercon96 by Henri Merkelo and Dimitri Grabbe. If I
recall correctly, methodically modifying the return plane with apertures
increases the inductance and decreases the capacitance (should be viewed as
per unit length changes, and relative to the rise time for the signal at
hand), thus increasing Zo relative to the impedance of the transmission line
in its unmodified state. I'm not sure if it is exactly what your are
looking for, but the name of the paper was "Advances in High Speed Signal
Management Techniques and Technologies". There may have been updates since
that time, but I am not specifically aware of any.

Regards,

Mark Gill, P.E.
EMC/Safety/NEBS Design
Nortel Networks - RTP, NC, USA

> -----Original Message-----
> From: Martyn Gaudion [SMTP:martyn@gaudionm.freeserve.co.uk]
> Sent: Wednesday, June 21, 2000 6:46 PM
> To: si-list@silab.eng.sun.com
> Subject: [SI-LIST] : Crosshatched ground planes
>
> Dear all...
>
> Can anyone help me with regard to crosshatching of ground
> planes.
>
> There does seem to be a practice of crosshatching to
> increase trace impedance whilst keeping impedance controlled
> lines at a manufacturable width, I would guess though that at
> higher frequencies the crosshatching looks like a large
> number of impedance discontinuities.
>
> Does anyone have any guidelines on this?
>
>
> Kind regards
>
>
> Martyn Gaudion
> Marketing Manager
> Polar Instruments
> Tel: + 44 1481 253081
> Fax: + 44 1481 252476
>
> www.polar.co.uk
> email: <martyn.gaudion@polar.co.uk>
> ----------------------------------------------------------
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