Hi I need help with my homework for school.
I've solved 2 stage BJT cascade amplifier before but this one is different because you have to consider the temperature. Unfortunately this type of problem was not discussed to us yet. So I posted it here to get some help.
Disregarding the temperature this is how I would solve it.
DC analysis
VE = VB - VBE = 0.82 - 0.7 = 0.12V
IE = VE/RE = 0.12V/1k = 0.12mA
re = 26mv/IE = 216Ω
AC analysis
Avtotal = Vo/Vi
Vo = β2Ib2(1K)
Vi = Ib1β1re + β1Ib1(100Ω)
Expressing Ib2 in terms of Ib1
Using Current Divider theorem
Ib1 = -β1Ib1(5k)/5K + (β2re2+β2(1k)
thus,
Avtotal = [β(1K)[-βIb1(5K)/5K +β(re2 + 1K)]/[Ibβ1(re1 + 100)
Avtotal = -12.75
Vo = Avtotal X Vi
Vo = -12.75 X 0.1 sin1000t
Vo = -1.275 sin1000t, but the real answer should be Vo = -4.08 sin100t V
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