hey all please help me with the (common emmiter-feedback resistor small signal analysis) i need the derivation of Rin and Ro and the gain pleasee
common emmiter-feedback resistor small signal analysis
- Thread starter mohammad.khatib
- Start date
You need to create small signal model of a amplifier and then find the unknown.
For example voltage gain is equal :
Au = Vout/Vin
Vin = Ib*H11 + Ie *Re
Ie = Ic + Ib = (hfe+1)*Ib
Vin = Ib*H11 + (hfe+1)*Ib *Re = Ib*(h11 + (hfe + 1)*Re)
Vout = -Ic*Rc = -Ib*hfe*Rc
Au = - ( Ib*hfe*Rc ) / ( Ib*(h11 + (hfe + 1)*Re) = - ( hfe*Rc ) / (h11 + (hfe + 1)*Re)
And h11 = (Hfe +1) * re = (Hfe +1) * 26mV/Ic
To find Rin you need to find
Rin = Vin /Iin
Rout = Vout/Iout
For example voltage gain is equal :
Au = Vout/Vin
Vin = Ib*H11 + Ie *Re
Ie = Ic + Ib = (hfe+1)*Ib
Vin = Ib*H11 + (hfe+1)*Ib *Re = Ib*(h11 + (hfe + 1)*Re)
Vout = -Ic*Rc = -Ib*hfe*Rc
Au = - ( Ib*hfe*Rc ) / ( Ib*(h11 + (hfe + 1)*Re) = - ( hfe*Rc ) / (h11 + (hfe + 1)*Re)
And h11 = (Hfe +1) * re = (Hfe +1) * 26mV/Ic
To find Rin you need to find
Rin = Vin /Iin
Rout = Vout/Iout
