My all discrete prefilter class-D
 

Hi,

I am interested in all discrete class D because I can make them with cheap parts, and availability.

During I redesign the UcD DIY I found that the my new design is good also for prefilter feedback. Actually I use two feedback prefilter for positive feedback oscillation and post filter to control gain.

But this time I just works on simulation. But the result from simulation seems good.

This is the filmuation file in LTSpice

Gate driver... on-off

Hi,

I'm no pro when it comes to feedback networks but usually when you have a mix of pre-post you end up with a load dependant amp that requires a zobel network. How does yours fair in this regard?

Hi Chris,

Of course I am not a pro too.... I need comments from this forum.

This is output plot...

I have no time to try on real circuit, I shall apply visa to Aussie..

Hi Chris,

This is post-filter feedback simulation that use same circuit from above pre-filter feedback.

I didn't see so much difference from the both simulation result. Please check and maybe you will find the difference.

in PDF

Does any guide to design zobel network for full range?

changing feedbak loop
 

Hi,

I just remove the feedback from post filter output. The gain control is done by control the voltage feedback signal from prefilter itself. Simply, if the feedback is higher than the gain is lower vice versa. So no matter for the gain control.

Simpler feedback loop than post filter indeed.

the output looks symmetric, again, frequency controlled easily just change value of C11, lower faster, vice versa.

Still no comment?