Re: [SI-LIST] : trace width for clock routing- wider/narrower?

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From: S. Weir (
Date: Sun Mar 12 2000 - 17:29:08 PST


Assuming stripline or microstrip construction, set the trace width to get
the required impedance and set the spacing to get the required crosstalk
isolation. The amount of attenuation for a given amount of spacing
required depends largely on the height to the nearest reflection plane, and
the parallelism to other traces. If 5/10 gives you 50 ohms, then 5/25 will
give roughly 6X the attenuation for any amount of parallelism beyond the
critical length that 5/10 gives you and still maintain 50 ohms.

The above does not hold true if you are using coplanar waveguide. There
were various discussions of CPW characteristics on this thread about a
month ago.


At 09:04 AM 3/13/2000 +0800, you wrote:

>Dear All SI experts,
>For clock routing, does wider trace width have more advantage than
>narrower one ,in term of better electrical properties, under the condition
>of same trace to space ratio and good match in impedance with source
>For example, 5 mils trace width with 10 mils trace spacing versus 10mils
>trace width with 20 mils trace spacing.
>Thank you for your helps in advance.
>John Lin
>SI Engineer
>Quanta Computer Inc.,Taiwan, R.O.C.
>Tel: 886+3+3979000 ext. 5183

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