Class D amp Working

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Now I have my Class D Amp ready. And it is a wooopping 650W of real power to drive my 2 HUNGRY Little Subs @ 2Ohms Load. I have powered it at 70V driving P150N Mosfets, and the amp is quite cool even at high power levels. As I have used it for my subs, I have used a active Linkwitz crossover, and it has a real base.
I have'nt used any feedback but have made short circuit & Overload circuit which works perfect.
There is only one problem that i have there is a 150Kz sine wave of 3V PP showing on my oscilloscope on the output, with no input to the amp, is it due to the dead time between the pulses.
I have used a Filter inductor of 550uH with .68uf Caps, which is not a perfect calculation.
Can anybody guide me to get a spread sheet for filter Calculation.

Regards,
Sonu.
 
There is only one problem that i have there is a 150Kz sine wave of 3V PP showing on my oscilloscope on the output, with no input to the amp, is it due to the dead time between the pulses.

Isn't this simply the residual of the switching frequency ? In this case I wouldn't care about it for sub use unless you use very long cables (and you might therefore be a source of RFI).

Regards

Charles
 
It was a problem with LC Filter, now it is solved,
I have also made 1500W RMS Amp to 2 Ohms Load working Perfectly OK, little heating in the Inductors.

Only thing i am concerned is still i have to perfectly design the LC Filter. I am not getting proper info on Butterworth Filter design.

Regards,
Sonu.
 
Only thing i am concerned is still i have to perfectly design the LC Filter. I am not getting proper info on Butterworth Filter design.

What do you mean by "perfectly" ?

Do you want to get rid of ALL the ripple ?

If so, I wouldn't recommend doing it ! While it was always recommended to suppress the carrier as much as possible in older texts, there is now a general agreement that you sacrifice less audio quality when using less steeper filters with higher cutoff frequencies.

Regards

Charles
 
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