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AM Detector simulation problem

Discussion in 'General Electronics Discussion' started by ektel, Jul 2, 2013.

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  1. ektel


    Jan 12, 2013

    I am doing a AM demodulator circuit simulation(envelope detector with precision rectifier). The circuit pic and output waveform pic are attached. The problem is the output waveform result after the diode(D1) labelled Vdiode.

    Are these waveform correct? I don't think the output waveform of the diode is correct. The diode D1 output and LPF output is same, whats wrong?

    Please comment and suggest


    Attached Files:

  2. duke37


    Jan 9, 2011
    The active rectifier circuit looks correct.

    The waveforms are a bit fuzzy, perhaps the time steps are too high.

    The diode output is connected to the circuit output so the waveforms will be the same.
  3. ektel


    Jan 12, 2013
    hi duke,

    the opamp output is rectified, as shown by the buttom graph, Is that ok? because opamp is performing the rectification not the diode or is it because the precision rectifier works this way and the signal get feedbacked, I don't know

    the output of diode shows like filter behaviour(as far as I know, not so sure)

    the filter output should be differ at least by some amount from the output of the diode otherwise the lpf has no meaning.

    I expected the signal just to have amplified by the opamp, and the rectified waveform to appear after the diode not in front of it, then some filtering of the high frequencies after the LPF.

    I am not so sure though as I am not good in circuit simulation and real world circuit implementation.

    Looking forward for comments

    Last edited: Jul 2, 2013
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