# Physical arguments to determine frequency behavior

Discussion in 'Homework Help' started by tquiva, Feb 16, 2011.

1. ### tquiva Thread Starter Member

Oct 19, 2010
176
1
Hi could someone please help me with this problem. My teacher designated the class to use Matlab to solve this problem. I'm currently having trouble with the first one. How would I go about using physical arguments to determine the very high and very low frequency behavior of the circuit?

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2. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
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What have you got for work so far?

Hint for number 1: If the input frequency is a huge number, say 1Ghz, what is the output? If the input frequency is a low number, say 1, what is the output. The answers to those questions by "inspection" let you know what type of filter you are working with.

For the rest, use the normal op-amp formulas, though taking the AC aspect of capacitors into account when deriving the characteristic equation.

3. ### tquiva Thread Starter Member

Oct 19, 2010
176
1
What if their is no input indicated on the circuit?

4. ### tquiva Thread Starter Member

Oct 19, 2010
176
1
At a low frequency, the capacitor becomes an open circuit. At a high frequency, the capacitor becomes a short. Does this mean it's a band-pass filter?

5. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
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You'll notice that if you completely remove the capacitors, the circuit will still have some gain under DC conditions. Since the circuit will pass DC, in that regard it is not a band pass type.

6. ### Georacer Moderator

Nov 25, 2009
5,142
1,266
I don't know how Matlab could really help you here. Maybe if you setup your equation system and then let it do the solving...