Re: [SI-LIST] : Physcially-small far-end LVDS terminations?

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From: Jim Freeman (freeman@broadcom.com)
Date: Thu Dec 16 1999 - 13:33:20 PST


Hi Eric,
    Another answer would be to ensure that the differential impedance of the board between the differential pairs is 100 ohms. Then you wouldn't need the resistors. I have performed Hspice sims on this and it works fine if the stackup/trace spacing is correct.

Jim Freeman

Eric Goodill wrote:

> Hi,
>
> I want to use the typical LVDS termination where you have two 50-ohm resistors in series placed between the two lines of the LVDS diff. pair and also have a cap at the junction of the resistors to ground. I have a jillion LVDS pairs to terminate at a high-pin-count ASIC, and I'm looking to squeeze more terminations per square inch. (There's no hope of putting the terminations inside the ASIC at this point.) I'm hoping some company makes a single three-pin part the has those two resistors and a cap even if not specifically for termination use.
>
> How about any other ideas for even higher density?
>
> Regards, Eric
> --
> Eric Goodill
> Siara Systems, ericg@siara.com
>
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