[SI-LIST] Re: PCB impedance coupon measurement

Kenny,
The standard coupon measurement is performed on a predefined topology =
located out of the actual board boundaries. The standard test equipment =
measures the reflected TDR wave and provides the average impedance. It =
normally checks if the value is within the accepted tolerance range and =
main result is 'pass/fail'.
Yet, TDR measurement can be taken on an actual trace within the PCB =
board boundaries (recommended). You will be required to define a new =
'pass/fail' criteria, unless you keep the same topology defined by the =
standard coupon test procedure.
 If the net is routed as a T-topology, then additional analysis should =
be done to separate the effect of each stub on the combined reflection =
back at the TDR tip. Note that if the stubs have about the similar =
length it will be very difficult to make the separation.   =20

- Dori Itzhaki
        Intel


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Kenny Frohlich
Sent: Thursday, August 24, 2006 8:00 AM
To: geethukarrthik@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: PCB impedance coupon measurement

Hi all,
  Since we're on the subject of PCB impedance coupon measurement, I have =
a question on TDR test.  I understand that TDR test is performed at the =
impedance coupon on the PCB.  Can a TDR measurement be taken on an =
actual trace on the PCB?  If a net is routed as a T-topology, can a TDR =
measurement take on this net?
  =20
  Thanks,
  Kenny
Geetha Balasubramanian <geethukarrthik@xxxxxxxxx> wrote:
  Dear Members,
Generally what is the frequency range for PCB impedance coupon =
measurement? Is it possible to measue the impedance of the coupon at a =
specific discrete frequency?
For better accuracy is it necessary to have 2 seperate bands one for USB =
full speed (12 Mbps) design and another for USB high speed (480 Mbps) =
design?

Thanking you all in anticipation

Geetha



---------------------------------
Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great =
rates starting at 1=A2/min.

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                        =09
---------------------------------
Want to be your own boss? Learn how on  Yahoo! Small Business.=20

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