Am I on the right track in solving this OpAmp problem?

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1. Mar 31, 2016

Aristotle

1. The problem statement, all variables and given/known data

2. Relevant equations
H(s)= Vo / Vi
Ideal op amp:
V+ = V-
Vo = V-

3. The attempt at a solution
To simplify the circuit, I noticed that the 200 ohm resistor and 60 microFarad capacitor are in parallel so:
Zp = (R/sC) / [(1+sRC)/(sC)] = R / [(1+sRC)]

Seeing that the Zp is in series with the 5 ohm resistor, I went ahead and used the voltage divider in search of Vo / Vin for the transfer function:

V- = 5 / [ 5 + (200/1+s(200)(60^-6)) ] * Vo

This is the part where I stopped since I'm not quite certain on how I can relate this to Vin. Can somebody lead me to the right track?
Thank you!

2. Mar 31, 2016

Staff: Mentor

For an OP-AMP with very high gain (ideally infinite), it causes V+ = V-

For your configuration here, V+ = Vin

3. Mar 31, 2016

Aristotle

Okay cool, I get an answer of:

H(s) = 5 / [ 5 + (200/1+s(200)(60^-6)) ]

Does this look correct?

4. Mar 31, 2016

Staff: Mentor

A little clumsy; it is usually written in a more standard form. I think you'd be needing more parentheses there, to make it universally correct.

5. Mar 31, 2016

Aristotle

H(s) = 5 / [ 5 + 200 / (1+s(200)(60^-6)) ]

And yes I know I have to make it in standard form, but am just verifying

Last edited: Mar 31, 2016