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50 II 2.6548 16.594
Bandpass Network Transfonnations 209
12.058
3.6534
10.356
4.2536
51.722
II
Figure 6.32.
, ,
pF and nH
Unnormalized bandpass network for Example 6.15.
previously described. Entering g3 =0.5046 and pressing key 0 yields the value
of the scaled bandpass input shunt (C =3.6534 pF); pressing key E displays its
resonating shunt (L= 12.058 nH). Similarly, key C is used with g2 and key 0
again with g,. The load resistor is 51.722 ohms. The load still is not in the
originally specified RC values, because the dependent Fano source resistance
has yet to be compensated. The resulting scaled bandpass network is shown in
Figure 6.32.
6.5.3. Norton Transformations. Example 6.16 in the previous section
showed that there is a need for introducing an ideal transformer somewhere in
the matching network to provide independence of input and output impedance
levels. An easy way to see how this might be accomplished is to derive
one case from the set of Norton transformations.
Consider the two networks and the expressions for their open-circuit
impedance parameters shown in Figure 6.33. The objective is to equate the
sets of z parameters and thus be able to replace the left-hand network with the
right-hand network. A case in point is seen in Figure 6.31. There are two
adjacent inductors. Incorporating an ideal transformer immediately to their
right (and impedance scaling to the right of that) would create a subsection
"
I
L,
l:n
"
2 1
"
L. L,
+ + + +
v, • L, V, V, L, v,
r
Z11 = sL 2
Z21 = ~; (1 2
=0 =snLz
" 2
Figure 6.33.
(right).
Z12 '" ~1 I =snLz
2 11 = 0
2 72 = sn 2 (L, + L z )
Inductive Norton
Z:n = s(L c + L b
}
transformation from a type-B L section (left) to a T section