i urgently need solution for this sinewave generator problem

Discussion in 'Homework Help' started by chintu84, Oct 18, 2006.

  1. chintu84

    Thread Starter New Member

    Oct 18, 2006
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    0
    The circuit below has been designed as a simple sine wave generator, to produce an output voltage with an amplitude of 5.9 V at a frequency of 1 kHz. The low-pass filter has been designed to have a low-frequency gain of -1 and a cutoff frequency of 1.5 kHz. What is the magnitude of the undesired frequency component in the output waveform at 5 kHz ?
    Express your answer in V, with an accuracy of 1 mV.

    i attwched the circuit diagram.
    i have tried this problem but i was not able get it.
    i have got the wrong answer.
    i have got it to be 0.2873.
    but the actual answer is 0.081
    i have tried it many times but i was not able to get it.
    can anyone help me urgently.
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,144
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    What is the slope of the filter response in dB/octave or dB/decade?
     
  3. chintu84

    Thread Starter New Member

    Oct 18, 2006
    6
    0
    nothing was given except for this data.
    can anyone help its urgent
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,791
    You cannot succeed in making this calculation until you can determine the order of the RC filter and what the slope of the rolloff is. That's the whole point of the problem.
     
  5. chintu84

    Thread Starter New Member

    Oct 18, 2006
    6
    0
    order of the filter is 1st and its slope is 20db/decade.
    can you help me fast.
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,791
    On a plot of gain versus frequency, the DC gain of -1 stands for 0 dB. The corner frequency of 1.5 kHz is where the actual response is 3 db down. It is from this point that you draw a straight line with a slope of 20 dB/decade. So the points are
    (1.5kHz, 0 dB) and (15 kHz, -20 dB)
    Now with a little bit of elementary algebra you should be able to figure out the attenuation at 5 kHz. Right?

    Once you have the attenuation factor in dB you can compute the actual level.
     
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