i have a question about the voltage gain of a CE transistor
i know that Av = -Rc / Re
but in some websites i read that it's equal to Av = Beta * Rc /Rb
why is it different ? and what is the right one ? and why is there no - in the one i found ? is it just ignored or for a reason ?
i tried to figure it out by my self and i got :
Av = Vout / Vin
Av = Iout * Rout / Iin * Rin
as Iout = ic , Iin = ib and Rout = the resistor connected in series with the output then
Rout = Rc and Rin = the resistor connected in series with the input then Rin = RE
so we get Av = ic*rc / ib*re
Av = βib*rc / ib*re
then Av = β rc / re
and i got a new equation which is not exist anywhere
can u help me to know what is the right equation for Av and how to get it ?
i know that Av = -Rc / Re
but in some websites i read that it's equal to Av = Beta * Rc /Rb
why is it different ? and what is the right one ? and why is there no - in the one i found ? is it just ignored or for a reason ?
i tried to figure it out by my self and i got :
Av = Vout / Vin
Av = Iout * Rout / Iin * Rin
as Iout = ic , Iin = ib and Rout = the resistor connected in series with the output then
Rout = Rc and Rin = the resistor connected in series with the input then Rin = RE
so we get Av = ic*rc / ib*re
Av = βib*rc / ib*re
then Av = β rc / re
and i got a new equation which is not exist anywhere
can u help me to know what is the right equation for Av and how to get it ?