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How sinusoidal oscillators produce sinusoids?

  1. May 14, 2012 #1


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    Why/How does a linear oscillator give >>>sinusoidal<<< output?

    I am basically confused how the sinusoidal signal output generates from a random noise? Why sinusoidal and not something else?

    Can this be explained from the characteristic equation/circuit poles?
  2. jcsd
  3. May 14, 2012 #2
  4. Jun 2, 2012 #3


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    Staff: Mentor

    An oscillator is a second order system, an amplifier with a gain fractionally over 1 and a tiny bit of non-linearity to drop the gain at the peaks to 0.999. The natural response of a critically damped second order system to a step or impulse is the sinusoid. With a loop gain of just over unity, it would be a sinusoid of ever-increasing amplitude, but tiny non-linearities are incorporated to level it out at an amplitude appropriate to the circuit parameters.
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