Digital Signal Processing Reference
In-Depth Information
t
d
v
s
R
s
R
t
Z
0
C
L
Figure 3-40
Transmission line terminated in a parallel
RC
network.
between
C
L
and the parallel combination of
R
t
and
Z
0
:
C
L
Z
0
R
t
R
t
+
Z
0
=
τ
1
(3-109)
Reflection from an Inductive Load
In the real world, when a transmission line
is terminated, there is usually a series inductance caused by the physical connec-
tion between the transmission line and the resistor. Some common examples of
this inductive connection are bond wires, lead frames, and vias. When a series
inductor appears in the electrical pathway of a transmission-line termination, as
depicted in Figure 3-41a, it will also act as a time-dependent load. Initially, at
L
=
1 nH
τ
d
=
250
ps
v
s
R
s
=
50
Ω
A
Z
0
=
50
Ω
R
t
=
50
Ω
0-2
V
(a)
2
A
1.5
1
0.5
B
0
0.2
0.3
0.4
0.5
0.6
Time, ns
(b)
Figure 3-41
(a) Transmission line terminated with a series
LR
load; (b) step response
showing reflections from the inductor.
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