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kliker
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[PLAIN]http://img43.imageshack.us/img43/9491/47613590.jpg
find Aus which is Vout/Vs = Vout/Vi * Vi/Vs
where Vi = ib*β*re and Vout = VL in this case
also we know that
Rc=2kΩ , Rb=430kΩ , Rs=1kΩ, RL=4kΩ, Vcc=10V, β=100.
MY ATTEMPT FOR A SOLUTION
Vout = ic*rL
where rL = RL||Rc
also Vi = ib*β*re
but we know that ic = β*ib
hence
Au = Vout/Vi = (β*ib*rL)/ib*β*re = rL/re
as i said rL = RL||Rc = 8000/6000 = 1.34 KΩ
I need to find re know, we know that re = 25mV/IE
BUT we don't know IE, I should analyze the dc circuit in order to find IE
in the DC circuit we have
10 - 0.7 = Ib*430000
hence Ic = β*(9.3/430000) = 2.15mA which is almost equals to IE since β is large enough
we know IE now
so
re = 25mV / 2.16mA = 11.57 Ω
hence Au = rL/re = 1340/11.57 = 115.8
now I need to find Vi/Vs
taking the ac circuit I get that Rs is in series with β*re||Rb
hence we have a voltage devider here and
Vi = Vs*(β*re||Rb)/(β*re||Rb+Rs)
hence
Vi/Vs = (β*re||Rb)/(β*re||Rb+Rs)
β*re||Rb = 1157||430000 = 1153 Ω
hence Vi/Vs = 1153/(1153+1000) = 0.53
so Aus = 0.53*115.8 = 62
am I correct?
thanks in advance
find Aus which is Vout/Vs = Vout/Vi * Vi/Vs
where Vi = ib*β*re and Vout = VL in this case
also we know that
Rc=2kΩ , Rb=430kΩ , Rs=1kΩ, RL=4kΩ, Vcc=10V, β=100.
MY ATTEMPT FOR A SOLUTION
Vout = ic*rL
where rL = RL||Rc
also Vi = ib*β*re
but we know that ic = β*ib
hence
Au = Vout/Vi = (β*ib*rL)/ib*β*re = rL/re
as i said rL = RL||Rc = 8000/6000 = 1.34 KΩ
I need to find re know, we know that re = 25mV/IE
BUT we don't know IE, I should analyze the dc circuit in order to find IE
in the DC circuit we have
10 - 0.7 = Ib*430000
hence Ic = β*(9.3/430000) = 2.15mA which is almost equals to IE since β is large enough
we know IE now
so
re = 25mV / 2.16mA = 11.57 Ω
hence Au = rL/re = 1340/11.57 = 115.8
now I need to find Vi/Vs
taking the ac circuit I get that Rs is in series with β*re||Rb
hence we have a voltage devider here and
Vi = Vs*(β*re||Rb)/(β*re||Rb+Rs)
hence
Vi/Vs = (β*re||Rb)/(β*re||Rb+Rs)
β*re||Rb = 1157||430000 = 1153 Ω
hence Vi/Vs = 1153/(1153+1000) = 0.53
so Aus = 0.53*115.8 = 62
am I correct?
thanks in advance
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