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Learnphysics
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Homework Statement
http://imgur.com/tJEPgbA
http://imgur.com/tJEPgbA
Homework Equations
The Attempt at a Solution
I started by focusing on the left Op-amp provided.
My methodology to solve this question was essentially to assume a virtual short circuit so that the negative input terminal of the op-amp goes to Vi. Using Vi, we can find current through C1.
Current through C1 is also the current through the parallel connection of resistances and capacitances.
Once we know the current between Vi and Vo, and we know the total resistance (impedence) we can solve for the voltage difference between Vi and Vo...
and also Vo/Vi. (which is the transfer function).
From that point I believe I need to get great the break frequency, (I'm not too sure how to do this, could anyone help?).
After I get the break frequency i can simply find the magnitude of the transfer function, express that on a logarithmic scale, and play around with the component values to get a 500radiens/sec break frequency. (Another question, how do I get my design to produce the 20db/decade (6per octave) rise? I mean all of the components fall into 'fb', and fb is 500. So what determines the gradient of the transfer function past the break frequency?)
Then, once I have that, I can repeat with the other circuit to get an idea how that one operates generally...
Then play around cascading them until I can create a 6db gain, and a 12db fall acting at the specific frequencies.
So i suppose what I'm asking is, once I get the transfer function, how do I go about pulling a break frequency out of it?
Il'l post working for this shortly (let me neaten it up a bit)
http://imgur.com/mZRJuyS
This is my attempt at the solution
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