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Digital Waves and Class D Amp

Discussion in 'Electronic Design' started by icegray, Jun 7, 2007.

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  1. icegray

    icegray Guest

    Hi,
    I need to design sinewave generator or wave generator (3V to 50V
    amplitute and 50Hz to 2KHz).
    This is my design idea;
    I create a wave by FPGA as PWM signal (10bit PWM resolution and 500KHz
    PWM freq.) and adjust frequency. Then I can adjust voltage by changing
    output voltage of Step-Up Regulators or Gain of Class D amp. And Class
    D amplifier increase or decrease wave amplitude. All of system can
    control with FPGA.

    PWM Controlled Step-Up Reg (+3V to
    +50V)

    -----------------------------------------------------------------
    |

    --------------------------------------
    Digital Wave (as PWM) ----- Class D Amp (Half Bridge) ------- LPF
    ----- Amplified Wave

    --------------------------------------
    |

    ---------------------------------------------------------------
    PWM Controlled Step-Up Reg (-3V to
    -50V)
    I use LC low pass filter. I don't understand when calculating L and C
    value Which frequency should i use for clear output signal?
    What is your idea?

    Thanks in Advance
     
  2. icegray

    icegray Guest

    I have tried to draw a diagram!!!
     
  3. joseph2k

    joseph2k Guest

    Just design a direct PWM source fed from the variable PS. As if PWM was the
    be all and end all. Some smart people did some startling things with 20
    years ago, but it is just one tool. BTW proper PWM for that output
    frequency range has about '100x the highest frequency of interest' base
    pulse rate.
     
  4. neon

    neon

    1,325
    0
    Oct 21, 2006
    just an dif. amp can do all that triagle sine square
     
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