Poles and Zeros

Discussion in 'General Electronics Chat' started by Mazaag, Feb 20, 2008.

  1. Mazaag

    Thread Starter Senior Member

    Oct 23, 2004
    255
    0
    I know that a pole is the value of s at which the magnitude of the transfer functino goes to infinity...why is it that when we draw a bode plot, a pole is represented by a drop in magnitude with roll off = 20db/dec?

    thanks
     
  2. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    I found a pretty good lecture explaining poles and zeros, with bode plots.

    http://web.mit.edu/2.14/www/Handouts/PoleZero.pdf

    I was under the impression that the pole occurs at the -3dB point, then it drops off to its zero at a rate determined by the order. So, a 1st order will drop off at 20dB/decade, 2nd 40dB/decade, etc. It has been a while since I took control systems, just don't ask me to draw a root locus :p

    Steve
     
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