CE Amplifier Gain Question

Thread Starter

eis4497

Joined Jul 6, 2019
16
Hi:

I am looking at a simple CE amplifier. With no emitter resistor bypass capacitor the
voltage gain is Av = rc / r'e + re = 286Ω / (2.57Ω + 100Ω) =2.78 which agrees to the
Spice sim.

However, if I fully bypass the emitter resistor the gain (based on the output voltage)
is like 74. If I calculate the gain it is Av = rc / r'e = 286Ω / 2.57Ω = 111.

I must be missing a piece of the puzzle.

Thanks

John
 

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SamR

Joined Mar 19, 2019
1,174
Typical due to variances in manufacturing tolerances in the components from exact as marked. When I breadboard I use multiturn resistor pots and you can use a cap decade box or variable caps to tweak it with and try to get max gain, remove clipping and waveshape a bit.
 

ci139

Joined Jul 11, 2016
725
you must know your signal source output impedance . . . driving the amplifier from ideal source gives you a surprise when connecting to the real one
 
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