Download Muddiest Points Week 8 2016

Muddiest Points Week 8 (Op Amps)
Question: My muddiest week point this week is what negative feedback is in an op-amp and how
it really works.
Answer: Negative feedback is connecting the output of the op amp back into the negative input
terminal, effectively creating a difference between the negative and positive voltage that is close
to 0, but not quite. In doing so the output voltage can be controlled and is usually equal to the
input voltage.
Question: How to find out the values of Vs and Rs when a complicated circuit is connected to a
Basic Inv Op Am Design.
Answer: According to the example in class today, what I need to do is just to calculate the
Thevenin Equivalent circuit and my Vs and Rs will be V(thevenin) and R(thevenin) respectively.
Question: The most confusing concept this week was that of input resistance and output
resistance. I had a hard time differentiating between the two. I understand why they matter, but
I didn't understand how to find them when just looking at parts of circuits. I also didn't
understand the difference between the two.
Answer: A good way I found to think about this concept was "looking into the circuit". If we
have inputs on the left and outputs on the right, the input resistance is the resistance encountered
when looking in from the left, and the output resistance is the resistance encountered when
looking into the right. Also, the output resistance is the Thevenin resistance, Rth.