Digital Signal Processing Reference
In-Depth Information
TABLE 4-1. Summary of Effective Capacitance and Inductance for a Couple Pair
Mode
Line 1
Line 2
C
effective
L
effective
hi
hi
lo
lo
Even
C
g
L
0
+
L
M
hi
hi
lo
lo
hi
hi
lo
lo
Odd
C
g
+
2
C
M
L
0
−
L
M
hi
hi
lo
lo
hi
lo
lo lo
hi
lo
lo lo
Quiet
C
g
+
C
M
L
0
hi
hi hi
lo
hi hi
lo
L
0
−
L
M
C
g
+
Z
0
,
odd
=
(4-37)
2
C
M
1
L
0
(C
g
+
C
M
)
ν
p,
isolated
=
(4-38)
1
=
ν
p,
even
√
(L
0
(4-39)
+
L
M
)C
0
1
ν
p,
odd
=
(L
0
(4-40)
−
L
M
)(C
g
+
2
C
M
)
Equations (4-35) through (4-40) are exact for the two-line case, and they give us
a simple way to analyze a coupled pair via a lattice diagram or simulation of a
single line using the effective characteristic impedance and effective propagation
velocity. We call the models created using this method single-line equivalent
models (SLEMs) [Hall et al., 2000].
It is interesting to note that the mutual inductance is always added or sub-
tracted in the opposite manner as the mutual capacitance for odd- and even-mode
propagation. The fields in Figure 4-9 help us understand why this is true. Con-
sidering odd-mode propagation as an example, the effect of mutual capacitance
must be added because the conductors are at different potentials. Additionally,
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