From: Nirmal Jain (email@example.com)
Date: Mon Jan 10 2000 - 17:33:02 PST
Long Wang wrote:
> I have a couple questions about backward crosstalk. In Ansoft 2D tool,
> the backward crosstalk coefficient can be calculated. My questions are :
> Assuming to consider 2 lines parallel each other, one line is active and
> the other is a victim.
> 1. In the result matrix of Ansoft 2D tool, the diagonal element is 0.5.
> What does that mean?
In this analysis, your near end is connected to a source with a source resistance of Zo, where Zo is the characteristic impedance of the transmission
line. Due to the voltage divider action, you have 0.5*Vs across the transmission line where Vs is the source voltage.
> 2. The off-diagonal element, for instance, is 0.01. Does it mean 1%
> coupling from the active line? Does the backward crosstalk depend on
> rise-time of a signal? If no, can you explain it?
Yes you are right, if the off-diagonal element is 0.01, it would mean you would have maximum 1% coupling from the active line. The picture below depicts
how backward crosstalk behaves. "a" is for a smaller rise time than "b"
| the crosstalk would saturate at Length = Vprop * Tr/2
| where Vprop is the propagation velocity and the Tr is the rise time
| /*/*************************** maximum near end xtalk
| a / /b
| / /
Hence the slope of the line (a, b) would change if your rise time changes.
Hope it makes sense. Feel free to give me a call if you have any further questions.
> Thanks a lot!
> Get Your Private, Free Email at http://www.hotmail.com
> **** To unsubscribe from si-list: send e-mail to firstname.lastname@example.org. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.
> si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list
-- Nirmal Jain Senior Application Engineer Signal Integrity Products
Ansoft Corp. 2560 Oak Rd. #322 Walnut Creek, CA 94596 (925) 938-6490 (Tel) (925) 215-2477 (Fax)
Four Station Square Pittsburgh, PA 15219 (412) 261-3200 (Tel) (412) 471-9427 (Fax)
**** To unsubscribe from si-list: send e-mail to email@example.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****
This archive was generated by hypermail 2b29 : Thu Apr 20 2000 - 11:34:33 PDT