From: Brad Underwood ([email protected])
Date: Wed Oct 18 2000 - 15:23:39 PDT
I have a question concerning k, the coupling coefficient described as:
1 / 1 + ( D^2 / H1 * H2 )
in the board geometry:
| D | pitch of traces
----- ----- trace1,trace2
H1 H2 Height
------------------------- Ref
When used to describe the coupling between single transmission lines
this 'unwanted' effect is called crosstalk and the target value of k
should low. When used to describe the coupling between paired traces of
a diff pair it seems that some value of coupling would be desired to
enhance common mode rejection at the receiver. If there were to litte or
no coupling then currents injected into one trace would not necessarily
also couple into the other trace of the pair. What is the target value
of this coupling coefficient. And what are the ramifications of values
greater than or less than ideal?
Regards,
Brad
....................................................
Brad Underwood
Hardware Engineer phone: (469) 330-1765
Metera Networks, Inc. cell: (214) 642-0769
1202 Richardson Dr, Suit 100 fax: (469) 330-1762
Richardson, Tx 75080
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