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Digital Waves and Class D Amp

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)

>> My first problem is output of Class D amp. I have been simulating (I use

Cadence PSpice) a Class D Amp. I can't give a clear signal. I think Something is wrong about LPF. I can't convert PWM (FET output) to Analog signal clearly. 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

Reply to
icegray
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Cadence PSpice) a Class D Amp. I can't give a clear signal. I think Something is wrong about LPF. I can't convert PWM (FET output) to Analog signal clearly.

I have tried to draw a diagram!!!

Reply to
icegray

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.

--
 JosephKK
 Gegen dummheit kampfen die Gotter Selbst, vergebens.  
  --Schiller
Reply to
joseph2k

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