Re: [SI-LIST] : Characteristic impedance

Dennis Tomlinson (det@tellabs.com)
Fri, 29 May 1998 09:45:16 -0500

Hi Philippe,

As noted by others, your cable is neither simple nor controlled.
If you cannot adequately beat down this problem using series termination
(not really "termination", rather more like damping, I'd say)
and/or edge rate control, then you might need to look into a
controlled impedance cable/interconnect solution (plus
appropriate termination).

Check the depth of your pockets, then navigate to:

http://www.precisionint.com/new/ribbon.htm

This is an Amp site which shows a ribbonized miniature coax
interconnect.

For some controlled impedance interconnects using flexible
circuit techniques, see:

http:// www.parlex.com/hsi.htm

and

http://www.allflex.thomasregister.com/olc/allflex/whento.htm

and many more.

Good luck,

Dennis

Disclaimer: I have no monetary interest in any of the above companies.

-------------
Poulet P. wrote:

> I wonder if any body can tell me how to calculate the characteristic
> impedance ( if any ) of a very simple Harness we use in our products.
> The harness is as follow:
>
> Made of 24 cables. Each cable is 26 AWG stranding ( among the most
> common you can buy ). One cable is gnd, one is VCC, remaining are
> control signals and data bus. Length is 8". One connectors used SMT
> 0.050" centerline and the other is through hole 2mm centerline.
> We are experiencing a lot of problem due to ringing overshoot and so
> fourth ( no surprise ).
> My main goal is to try to terminate properly the lines and the problem
> is how to deal with this cable and the discontinuity PCB cable PCB.
>
> Thanks in advance
>
> --
> Philippe Poulet
> Hardware Engineer
> RICOH Corp
> 3001 Orchard Pkwy
> San Jose CA95134-2088
> Ph: (408) 944-3347
> Fax: (408) 434-5390
>
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