Bjt CE amplifier

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06:45:34

Bjt common emitter amplifier.

We want a gain Av and a collector current Ic, and we have a Vcc supply and a typical hFE. So:
Ve = Vcc/(2Av+1)
Re=Ve/IC
Rc=Av*Re
Then to bias the base:
Rb = Re*hFE/10
Vb=Rb*IC/hFE+0.65+Ve
and  so:
Rh=Vcc*Rb/Vb
Rl=Rhb*Rb/(Rhb-Rb)

Vout swings between Vcc and 2*Ve.

Zin=Re*hFE//Rh//Rl.
Cin=1/(2πZin*f)
Power dissipated by transistor is (Vcc-Ve)*Ic.

Re makes transistor less dependent on beta and fixes thermal issues also:
k=-2.5mV/°C,
∆T=Ve/(20*k).

Enjoy

published 4 years ago

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