Voltage Regulators - Problem 4.b

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,755
Ok, Ib may not be IR1 + IRz but this Ib is not the same Ib as before, right?

Edited;

Because in the previous circuit, IB was never flowing through R1 or Rz and now it is! Is my reasoning correct?
 
Last edited:

Jony130

Joined Feb 17, 2009
5,487
I don't know what to say. To find ro you have draw a small-signal model circuit. And now based on this new circuit you need to find ro by using network analysis.
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,755
@Jony130 ok, about your post #18, the equation for Ib, suggests that Ib is the totall current of the equivalent circuit I attached, right?

After calculating the equivalent resistance, the total current will be the voltage applied to the equivalent resistance, right?

So in the attached circuit, Itotal is your Ib, correct?

4.b.png
 

Jony130

Joined Feb 17, 2009
5,487
The dependant current source has only influence on Ix. The "base" current is constant and always equal to Vx/(Rs+hie).
 
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