Howdie Alexis:

Sounds like you need series resistive terminations.  Do you have access to PSpice?  This will help you pin
down the correct values to use at the load through simulation.  Also, what layout s/w are you using?  PADS
POWERPCB allows you to control impedance with design rules that are passed directly to the Cadence SPECCTRA
route engine?

Good Luck.

Meehan, Alexis wrote:

> I have a data sheet for a part which requires the TD+ and TD- signals to
> be routed as matched length and
> with "a characteristic single-ended impedance of 50 ohms". I understand
> the matched length part, and I
> know how to attain an impedance of 50 ohms on the entire PCB, but what
> do I need to do to insure 50
> ohms impedance on just 4 traces? I'm using 6 mil traces with 6 mil
> spacing.
> Thanks in advance for any advice on this.
>
> **********************************************************
> Alexis Meehan            WaveSpan Corporation
> Engineering Services     500 N. Bernardo Avenue
> Tel: 650-237-8365        Mountain View, CA 94043
> Fax: 650-919-0191        http://www.wavespan.com
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