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LC Resonance and Harmonics

  1. Jun 4, 2013 #1
    I'm trying to better understand this circuit:
    and how the added inductors (L3, and L4) and Capacitor create a harmonic. I fully understand how to calculate the resonance for the main circuit but how would I calculate the harmonic that the added circuit creates?
  2. jcsd
  3. Jun 4, 2013 #2
    What are the input and output nodes of the circuit?
  4. Jun 4, 2013 #3


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    Science Advisor

    This circuit cannot generate anything. It can react to input signals and give different results depending on the input frequency.

    The result also depends on where you feed an input signal in, and where you look at the output.

    Roughly, this is a series tuned circuit resonant at about 6 MHz in parallel with a parallel resonant circuit at 6 MHz.

    I added a sinewave signal source in series with a 10K resistor across the series tuned circuit and got a parallel resonance (a peak) at about 3.2 MHz and a series resonance (a null) at about 6.2 MHz measured in the same place.
    This was using LTSpice, a free program which I urge you to get familiar with.
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