From: Mike Jenkins ([email protected])
Date: Thu Jun 22 2000 - 13:46:46 PDT
Martyn,
Just one more caveat on crosshatched planes. If the return
currents are forced to take a non-straight-line path under
the trace, the effective velocity of propagation will be
slower. (This actually happened a number of years ago to
some folks trying to make their signals faster by lowering
capacitance. They used a 45 degree crosshatch and got
slower signals instead.)
Mike
Martyn Gaudion wrote:
>
> 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: <[email protected]>
> ----------------------------------------------------------
> Download your FREE evaluation
> PCB controlled impedance calculator
> "CITS25" from www.polar.co.uk
> ----------------------------------------------------------
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mike Jenkins Phone: 408.433.7901 _____ LSI Logic Corp, ms/G715 Fax: 408.433.7461 LSI|LOGIC| (R) 1525 McCarthy Blvd. mailto:[email protected] | | Milpitas, CA 95035 http://www.lsilogic.com |_____| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~**** To unsubscribe from si-list or si-list-digest: send e-mail to [email protected]. In the BODY of message put: UNSUBSCRIBE si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu ****
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