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Amplifier circuits

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As I'm studying for my 3rd class Amateur radio certificate[1] in Japan[2], I wanted to write down some notes on amplifier circuits.

Amplifier types

Common emitter amplifier

Common emitter amplifier in the Falstad circuit simulator

In Japanese, this called エミッタ接地増幅回路[3].

Falstad circuit emulator text[4]:

$ 1 0.000005 13.097415321081861 66 5 50 5e-11
t 208 208 288 208 0 1 -6.335290598254659 0.6267237961459291 100 default
r 288 192 288 96 0 1200
r 208 208 208 96 0 20000
w 208 96 288 96 0
v 96 352 96 208 16 1 100 1 0 0 0.5
c 208 208 96 208 4 0.000003 1.3999061550528193 0.001 0
w 96 352 208 352 0
c 336 224 336 352 4 0.0000022999999999999996 1.0340239322574427 0.001 0
w 336 352 416 352 0
p 416 192 416 352 3 0 0 10000000
R 416 96 448 96 0 0 40 12 0 0 0.5
w 288 96 416 96 0
207 416 192 448 192 4 Vout
g 288 352 288 384 0 0
w 416 192 288 192 0
w 336 352 288 352 0
r 288 224 288 352 0 220
w 288 224 336 224 0
207 416 352 448 352 4 0v
r 208 208 208 352 0 3600
w 208 352 288 352 0
o 4 64 0 x281012 8.250148878587748 0.0001 0 3 0 20 0 4 3 Infinity 0 9 0 500 0

Observations:

  • The output voltage is 180 degrees out of phase with the input voltage.
  • Increasing the AC frequency from 100 Hz to 1000 Hz introduces clipping on the output.

Notes

  1. 国家試験 受験案内 www.nichimu.org.jp
  2. I realize writing this resembles "Photo of X -> :|, Photo of X in Japan :O"
  3. 第3級ハム国試要点マスター 2026年版発行 CQ出版社 ISBN978-4-7898-1932-9
  4. Circuit Simulator Applet www.falstad.com/circuit