Digital Signal Processing Reference
In-Depth Information
5
5
S
=
10
1.3
A
V
0.5
V
4
A
=
aggressor
V
A
,
A
+
0
V
=
victim
(a)
0.5
V
A
−
ε
r
=
4.5, tan
δ =
0.017
0
V
100 ps
5
5
5
5
4
4
S
=
10
A
+
A
−
V
+
V
−
4
(b)
5
5
S
=
28
A
V
4
(c)
Figure 7-5
Cross sections used to compare differential versus single-ended crosstalk:
(a) two single-ended signals; (b) two differential pairs with the same pair spacing as that
of the single-ended signals in (a); (c) two widely spaced single-ended signals that occupy
the same board area as the differential pairs (dimensions in mils).
0.25
v
differential
=
(
V
+
)
−
(
V
−
)
0.2
Single-ended
S
0.15
28
mils
(
Figure
7
-
5
c
)
=
Differential
S
0.1
10
mils
(
Figure
7
-
5
b
)
=
0.05
0
−
0.05
Single-ended
S
−
0.1
10
mils
(
Figure
7
-
5
a
)
=
−
0.15
−
0.2
−
0.25
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
Time, ns
Figure 7-6
Crosstalk for the cross sections in Figure 7-5 demonstrating that differential
signaling does not reduce crosstalk compared to single-ended signaling if the same board
area is used. However, if the spacing between differential pairs is similar to the spacing
between single-ended signals, crosstalk in reduced (5-in. microstrip).
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