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HAM Radio 1
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1983-10-04
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57 lines
here by placing a small inductor between the drain and the
gate. We will also add some tuning and matching circuitry to
the input and output, the result being a stable, tuned ampli-
fier for 50-51 MHz (the 6-meter amateur band). The value of
the inductor (5.518 uH) is derived by way of using Cgd as part
of a tank circuit. We add a 1000 ohm resistor at the gate to
enhance the stability and make the matching easier, and the
three-element matching circuitry on the input and output is
derived by the use of a Smith chart. We can afford to be a
little sloppy here, as this amplifier is to be used later as
an example for optimization in a later chapter on that subject.
Our circuit is:
ELEMENT PARAMETER
TYPE NUM #1 #2 #3
1 INP 1 177
2 INS 2 462
3 CRP 3 1000 14
4 CPP 5 8.59
5 INS 6 1114
6 INP 7 177
7 INS 8 5518
8 TWO 9 FILE NAME = J309
9 PAR 4 8 9
10 CAX 10 1 7
11 END 10
Note that element 4 is actually in line 9. It is not
necessary that the elements be arranged in ascending order
for the CAX instruction, only that they appear before it.
Now, our amplifier has the following characteristics:
FREQ S11 S21 S12 S22
in GHz in dB in dB in dB in dB
0.05 -12.1 25.58 -36.83 -13.75
0.0502 -18.11 25.71 -41.15 -17.17
0.0504 -31.35 25.53 -50.88 -12.72
0.0506 -17.61 25.07 -51.38 -8.77
0.0508 -12.61 24.41 -42.51 -6.33
0.051 -9.95 23.63 -38.87 -4.79
FREQ INPUT STABILITY CIRCLES
in GHz DIST ANGLE RADIUS I/O K
0.05 325.14 160.86 326.9 I 1.75
0.0502 18.92 156.91 22.04 I 2.92
0.0504 18.01 89.01 28.79 I 8.78
0.0506 8.58 -168.8 3.45 O 8.82
0.0508 5.9 -173.3 3.58 O 2.94
0.051 4.65 -173.0 3.1 O 1.77
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