Hi there,
in a common emitter circuit, I calculate the RE ( Emitter Resistor) and RC with
Ib = Ic / BF
R3 = (Vcc - Uce - Ure) / Ic
RE = Ure / (Ic + Ib)
But these Formulas do not consider the internal resistors rb and rc.
A comparison with Qucs and LTSpice confirms this. ,The BJT Model in this case is
.model myNPN NPN
+ IS=2e-16
+ BF=140
.ENDS
If RE is attached to the model (0.4 for example), the calculates RE is wrong.
Does anyone know the exact formulas?
THX
Guenter
in a common emitter circuit, I calculate the RE ( Emitter Resistor) and RC with
Ib = Ic / BF
R3 = (Vcc - Uce - Ure) / Ic
RE = Ure / (Ic + Ib)
But these Formulas do not consider the internal resistors rb and rc.
A comparison with Qucs and LTSpice confirms this. ,The BJT Model in this case is
.model myNPN NPN
+ IS=2e-16
+ BF=140
.ENDS
If RE is attached to the model (0.4 for example), the calculates RE is wrong.
Does anyone know the exact formulas?
THX
Guenter