4
reflected depends on the degree of impedance mismatch. The voltage reflection coefficient, (Z1-
Z0)/(Z1+Z0) is a measure of this mismatch:
Figure 2. Impedance reflection across a boundary.
Crosstalk
Crosstalk is undesired energy imparted to a transmission line due to signals in adjacent lines. Crosstalk
magnitude is dependent on risetime, signal line geometry and net configuration (type of terminations,
etc.).
Quantitatively, this energy results from mutual inductances and capacitances in the Telegrapher's
Equations:
Crosstalk is often discussed in terms of forward and backward crosstalk coefficients. These are
determined by the ratio of mutual capacitance to self-capacitance, and mutual inductance to self-
inductance. If a disturbing line j is coupled to a victim line i that is terminated in its characteristic
impedance, these coupling coefficients are
t
V
C
t
V
C GV
x
I
t
V
C
t
V
C GV
x
I
t
I
L
t
I
L RI
x
V
t
I
L
t
I
L RI
x
V
M
M
M
M
1 2
2
2
2 1
1
1
1 2
2
2
2 1
1
1
