Solving for 3dB frequency appproximations

  • Thread starter area5x1
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  • #1
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Homework Statement



I have the transfer function:

F(s) = s^3 / ((s+12)(s+550)(s+680))

Find the lower cutoff frequency (3dB point)

Homework Equations



s = jw

The Attempt at a Solution



I set the equation equal to 1/sqrt(2), use s = jw, and try to solve for the frequency. Now I'm just supposed to "Put it into your calculator and off I go", but what exactly do I put into my calculator? I have a Ti-84, is that able to solve these types of problems?

What's throwing me off is the imaginary term 'j', I'm not exactly sure what to do with it when solving this polynomial.
 

Answers and Replies

  • #2
rude man
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You need to find the magnitude of a complex number.

It's |a + jb| = sqrt(a^2 + b^2).

So find a and b for your transfer function and set the magnitude = 1/sqrt(2).
 

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