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HAM Radio 1
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1983-10-06
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57 lines
ond changed very little. This serves to demonstrate the use-
fulness of sensitivity analysis. The filter now has the fol-
lowing characteristics:
FREQ S11 S21 S12 S22
in GHz in dB in dB in dB in dB
0.3 -32.71 0 0 -32.71
0.6 -17.3 -0.08 -0.08 -17.3
0.9 -13.18 -0.21 -0.21 -13.18
1.4 -0.04 -19.99 -19.99 -0.04
1.7 0 -29.98 -29.98 0
We see here that the filter behaves almost exactly as we
had requested with very minor exceptions. Now, this becomes a
good starting point for realizing the filter in hardware.
b. FEEDBACK AMPLIFIER
Now, let's try something a little more difficult. Let's
take the feedback amplifier on page 21 and smooth out the re-
sponse. This is going to require that we make certain judge-
ments in the optimization elements this time, as we have eight
that we can select from. We choose the following objectives:
FREQ OBJECTIVES
in GHz S11 WGT S22 WGT S21 WGT
0.05 -15 10 -15 10 25 10
0.0505 -15 10 -15 10 25 10
0.051 -15 10 -15 10 25 10
These objectives are derived from the observations made
from the previous response analysis. 25 dB of gain was readily
attainable, but the return losses left quite a bit to be de-
sired. Therefore, an idealistic -15 dB for the return losses
was chosen in an attempt to improve on these two parameters.
In choosing optimization elements, it is important that we
first note that the value of the neutralization inductor, INS 8,
was chosen so as to enhance the stability of the amplifier, as
was the parallel resistor at the gate (the first parameter of
CRP 3). This leaves us with six candidates for optimization.
An initial stability analysis shows:
ELEMENT PARAMETER GRADIENT
TYPE NUM NUM VALUE
1 INP 1 1 177 -2.143
2 INS 2 1 462 1.818
3 CRP 3 2 14 10.482
4 CPP 5 1 8.59 1031.067
5 INS 6 1 1114 7.457
6 INP 7 1 177 -0.731
ITERATION #0 ERROR = 540.8
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