Page 178 - Complete Wireless Design

Amplifier Design

Amplifier Design 177

6. Calculate I I /ß
B C
7. Calculate V V V
BB E BE
8. Give a value for I of 1.5 mA. (The larger in value I is, the more
BB BB
improved will be the stability, but power dissipation increases.)
9. Calculate R V /I
1 BB BB
V V
CC
BB
10. Calculate R
2 I I
BB B
11. X 1 ohm
CE
To design a moderately temperature stable collector feedback Class A or AB ampli-
fier for HF, VHF, UHF and above (Fig. 3.82):

1. Select a Q point for the transistor, such as: I 10 mA; V 12 V; ß 50;
C CC
V 6 V. (I and V should be the same as the available S-parameter files
C C C
for the active device, as found in *.S2P format.)
2. Calculate I I /ß
B C
V 0.7

C
3. Calculate R ß
F I
C
V V
CC
C
4. Calculate R
C I I
B C

Figure 3.82 A Class A high-frequency amplifier.

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