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PWM to Sine Wave Converter

Discussion in 'General Electronics Discussion' started by vinit2100, Jul 23, 2014.

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  1. vinit2100

    vinit2100

    100
    1
    Oct 21, 2013
    How can we get a Sine Wave from PWM Sugnal. I read somewhere that RC filtering does this conversion. So how will we design the R and C values ? I am attaching a waveform that i want to get in Sine wave. Please help me in this
     

    Attached Files:

  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Are you sure your screen shot is PWM, it looks more like PPM. The pulses seem to be the same width with differing timing shift.

    A PWM signal that represents a sine wave can be turned into a shaggy sine wave by using an RC filter. You would put the corner frequency just above the frequency of the sine wave, which is hopefully about two decades below the PWM frequency (100 points in the sine period). Then the PWM frequency will be suppressed by 40dB.

    Bob
     
    KrisBlueNZ likes this.
  3. vinit2100

    vinit2100

    100
    1
    Oct 21, 2013
    The width of the signal is same !!!
     
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Yes, that is the point. PWM means Pulse Width Modulation. The width of the pulses changes. PPM means pulse position modulation, where the width of the pulse stays the same but the space between pulses changes, which is what your signal looks like. Where does the signal come from?

    Bob
     
  5. vinit2100

    vinit2100

    100
    1
    Oct 21, 2013
    The signal comes from an audio codec IC called AIC 111
     
  6. vinit2100

    vinit2100

    100
    1
    Oct 21, 2013
    Hi I am attaching a snapshot of AIC 111 output(VOUT_P of AIC 111) .. actually this is the output of H bridge amplifier. VOUT_P and there is another signal Called VOUT_M which is just the complement of the attached image. I want to covert this signal into a Sine wave. How will i design the filter circuit ?
     

    Attached Files:

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