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Digital Waves and Class D Amp

I

icegray

Jan 1, 1970
0
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
 
I

icegray

Jan 1, 1970
0
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

I have tried to draw a diagram!!!
 
J

joseph2k

Jan 1, 1970
0
icegray said:
I have tried to draw a diagram!!!
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.
 

neon

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