Digital Signal Processing Reference
In-Depth Information
l 2
z 0
l 1
v s
Receiver 1
R s = Z 0
z 0
l 3
z 0
0-2 V
Receiver 2
T 3 T 2
Γ 1
Γ 2
Γ 3
Γ 4
Γ 5
0
250 ps
a
a
a
g
b
c
d
e
f
500 ps
A
b
B
750 ps
y
1000 ps
Figure 3-35 Lattice diagram of a T-topology when the leg lengths are not equal.
end of the long line (receiver 2). The initial voltage step launched onto line 1 is
Z 0
50
v i = v s
+ R s =
·
50 =
2
1
Z 0
50
+
The reflection and transmission coefficients looking from line 1 into the junc-
tion is
(Z 0 / 2 ) Z 0
(Z 0 / 2 ) + Z 0
25
50
1
3
2
=
=
50 =−
25
+
2
3
Consequently, the initial voltage launched into both legs (lines 2 and 3) is
=
+ 2
=
T 2
1
2
3
This voltage ( v a ) travels down each leg and doubles when it arrives at the open
circuit ( 4
v a =
T 2 v i
=
= 5
=
1 ) . Therefore, the voltage at receiver 1 ( v α ) occurs at t =
375
ps, which is the delay of line 1 plus line 2 (the short leg).
2
3
v α = v a + v b =
v b = v a 4
=
4
3
 
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