What is the effect of feedback on input and output impedances?

  • Thread starter Thread starter tanaygupta2000
  • Start date Start date
  • Tags Tags
    Feedback Impedance
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
4 replies · 2K views
tanaygupta2000
Messages
208
Reaction score
14
Homework Statement
An amplifier has a voltage gain Av = 1000 , input impedance 1 kΩ and output impedance 500Ω A
fraction βv = 0.1 of the output voltage is fed back in the series in opposition to the input voltage. The
input and output impedance after the feedback are given respectively by the approximate values ?
Relevant Equations
A' = A/(1-βA)
I know that when the feedback is connected, the voltage gain changes by the above formula. But I don't know how to find final values of input and output impedances.
 
Physics news on Phys.org
How do input and output impedance change when you apply feedback? Have you studied that point?
 
How would you measure the input impedance (i.e. what information about this circuit do you need to calculate this)? How would you measure the output impedance?
Have you drawn a schematic of this circuit yet?
 
  • Like
Likes   Reactions: berkeman
You have mentioned a formula for the gain A´ with feedback ...when you insert the mentioned value βv = 0.1 , will the gain be larger or smaller than A (without feedback)? What do you expect ?

(By the way: An answer to your question can be found in each relevant textbook...did you already spend some time for searchnig?)