Crosstalk noise onto a floating line

<prev| up |next>


An active line-1 is terminated by resistances at both ends, and a passive line-2 is floating.

The voltage on active line is the same in the case of a single line:

where

The voltage on passive line is proportional to that on active line:

where ξ is the crosstalk coefficient:

An example waveform for a rising step input v01(t) with rise time tr=τ/2:

We will calculate the crosstalk voltage onto a floating line.

***

We start from the general solutions in even and odd mode:

Transforming the variables of even and odd mode to those of each line:

we obtain the general solutions for each line:

where we have assumed that the propagation speeds are equal in even and odd mode.

For convenience, expressing (3),(4) in terms of Z0 and parameter ξ

,we have

***

We are now ready to calculate the crosstalk noise onto a floating line.

Boundary conditions are:

then Laplace transformed boundary conditions are

***

First, inserting the general solutions (1),(3') into the boundary conditions of line-1:

Eliminating the pair of Va2,Vb2:

After some manipulation we obtain:

where τ is the propagation time from x=0 to x=l, and ΓST are reflection coefficients at source and termination end.

This result is the same in the case of a single line. (Multiple reflection in a terminated line)

***

Next, inserting the general solutions (2),(4') into the boundary conditions of line-2:

Eliminating the pair of Vb1,Vb2 or Va1,Va2:

We find that the voltage on passive line-2 is proportional to that on active line-1.

This parameter ξ indicates the ratio of amplitude between passive and active line, so it is called crosstalk coefficient.


<prev| up |next>