Hello there,
I meant to post this sooner but some problems came up at home with the car that i have to attend to. It's been a problem because it is an electrical item and i dont have a schematic so i have to make one myself. Quite a challenge with many parts and many are SMD parts hard to identify.
Anyway, here are the drawings and the solutions to the DC bias point and AC gain. Some are with 're' and some are without.
I hope to do more with this as time goes on.
First the equations, then the drawings will be attached. See what you think and if you can reconcile 're' or 'gm' with the solutions.
Note R5 represents the notorious 're'. In the top diagram 're' is zero, in the bottom 're' is non zero and calculated from VT and the emitter current 'ie'.
Also note E3 in the solutions is Vbe in the drawings.
** Vdc out with R5=0:
Vc=(B*E2*R3*R6+E2*R3*R6+B*E2*R2*R6+E2*R2*R6+B*E3*R3*R4B*E2*R3*R4+B*E3*R2*R4+E2*R2*R3)/(B*R3*R6+R3*R6+B*R2*R6+R2*R6+R2*R3)
** Vdc out with R5=non zero (Vbe as shown in the drawing):
Vc=(B*E2*R3*R6+E2*R3*R6+B*E2*R2*R6+E2*R2*R6+B*E2*R3*R5+E2*R3*R5+B*E2*R2*R5+E2*R2*R5
+B*E3*R3*R4B*E2*R3*R4+B*E3*R2*R4+E2*R2*R3)/(B*R3*R6+R3*R6+B*R2*R6+R2*R6+B*R3*R5+R3*R5+B*
R2*R5+R2*R5+R2*R3)
** for AC only, R5=0:
(AC gain)=(s^2*B*C1*C2*R2*R3*R4*R7)/((s*B*C1*R2*R3*R6+s*C1*R2*R3*R6+s*B*C1*R1*R3*R6+s*C1*R1*
R3*R6+B*R3*R6+R3*R6+s*B*C1*R1*R2*R6+s*C1*R1*R2*R6+B*R2*R6+R2*R6+s*C1*R1*R2*R3+R2*R3)*
(s*C2*R7+s*C2*R4+1))
** for AC only, R5 included:
(AC gain)=(s^2*B*C1*C2*R2*R3*R4*R7)/((s*B*C1*R2*R3*R6+s*C1*R2*R3*R6+s*B*C1*R1*R3*R6+s*C1*R1*
R3*R6+B*R3*R6+R3*R6+s*B*C1*R1*R2*R6+s*C1*R1*R2*R6+B*R2*R6+R2*R6+s*B*C1*R2*R3*R5+s*C1*R2*R3*R5
+s*B*C1*R1*R3*R5+s*C1*R1*R3*R5+B*R3*R5+R3*R5+s*B*C1*R1*R2*R5+s*C1*R1*R2*R5+B*R2*R5+R2*R5+s*C1*
R1*R2*R3+R2*R3)*(s*C2*R7+s*C2*R4+1))
I meant to post this sooner but some problems came up at home with the car that i have to attend to. It's been a problem because it is an electrical item and i dont have a schematic so i have to make one myself. Quite a challenge with many parts and many are SMD parts hard to identify.
Anyway, here are the drawings and the solutions to the DC bias point and AC gain. Some are with 're' and some are without.
I hope to do more with this as time goes on.
First the equations, then the drawings will be attached. See what you think and if you can reconcile 're' or 'gm' with the solutions.
Note R5 represents the notorious 're'. In the top diagram 're' is zero, in the bottom 're' is non zero and calculated from VT and the emitter current 'ie'.
Also note E3 in the solutions is Vbe in the drawings.
** Vdc out with R5=0:
Vc=(B*E2*R3*R6+E2*R3*R6+B*E2*R2*R6+E2*R2*R6+B*E3*R3*R4B*E2*R3*R4+B*E3*R2*R4+E2*R2*R3)/(B*R3*R6+R3*R6+B*R2*R6+R2*R6+R2*R3)
** Vdc out with R5=non zero (Vbe as shown in the drawing):
Vc=(B*E2*R3*R6+E2*R3*R6+B*E2*R2*R6+E2*R2*R6+B*E2*R3*R5+E2*R3*R5+B*E2*R2*R5+E2*R2*R5
+B*E3*R3*R4B*E2*R3*R4+B*E3*R2*R4+E2*R2*R3)/(B*R3*R6+R3*R6+B*R2*R6+R2*R6+B*R3*R5+R3*R5+B*
R2*R5+R2*R5+R2*R3)
** for AC only, R5=0:
(AC gain)=(s^2*B*C1*C2*R2*R3*R4*R7)/((s*B*C1*R2*R3*R6+s*C1*R2*R3*R6+s*B*C1*R1*R3*R6+s*C1*R1*
R3*R6+B*R3*R6+R3*R6+s*B*C1*R1*R2*R6+s*C1*R1*R2*R6+B*R2*R6+R2*R6+s*C1*R1*R2*R3+R2*R3)*
(s*C2*R7+s*C2*R4+1))
** for AC only, R5 included:
(AC gain)=(s^2*B*C1*C2*R2*R3*R4*R7)/((s*B*C1*R2*R3*R6+s*C1*R2*R3*R6+s*B*C1*R1*R3*R6+s*C1*R1*
R3*R6+B*R3*R6+R3*R6+s*B*C1*R1*R2*R6+s*C1*R1*R2*R6+B*R2*R6+R2*R6+s*B*C1*R2*R3*R5+s*C1*R2*R3*R5
+s*B*C1*R1*R3*R5+s*C1*R1*R3*R5+B*R3*R5+R3*R5+s*B*C1*R1*R2*R5+s*C1*R1*R2*R5+B*R2*R5+R2*R5+s*C1*
R1*R2*R3+R2*R3)*(s*C2*R7+s*C2*R4+1))
Attachments

36.9 KB Views: 38