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Square waves and nonlinear loads?

  1. Feb 28, 2012 #1
    Nonlinear loads produce odd harmonics which produce square waves.

    What will happen if a square wave is pulsed into a nonlinear load?

    Would the same square wave be seen across the load or would the nonlinear load change the square wave?

    If a capacitor is nonlinear (i.e. capacitance changes with applied voltage) and a square wave is applied to it what would occur?
  2. jcsd
  3. Feb 28, 2012 #2
    Define your non linear, it is such a general term. It's like saying the lens has distortion.....what?....barrel, pinch cushion, chromatic aberration or what?!!!
  4. Feb 29, 2012 #3


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    Staff: Mentor

    This is not a true generalization.
    Generally, the output will be a waveform altered in some way/s, i.e., it won't be a squarewave.
    A varactor? The result depends on the circuit.
  5. Feb 29, 2012 #4
    I think usually a nonlinear load is one that would have a non-linear "transfer function", where it can produce new frequencies not in the spectrum of its input signal. The problem with that is a transfer function is linear by definition, so it has to be described in other ways. An example would be considering a mixer as a nonlinear load. Basically, the system cannot be described by a set of linear equations, and so it cannot be solved to determine its output.

    Nonlinear loads don't necessarily produce odd harmonics (not sure if you're using odd in the mathematical sense or in the verbal sense), and odd harmonics don't necessarily produce square waves. Odd harmonics can produce an infinite family of waveforms that are not square waves.

    Your other questions give too general information to give you an answer, but its interesting to think about. A nonlinear load can look like a linear load within certain ranges, and so a square pulse in can be a square pulse out, but it wouldn't be true for all conditions. An example is a positive biased square pulse through a diode into a resistor, where its output would have the same frequency content as its input ideally. It is still a nonlinear system tho.
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