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kartino 2nd August 2006 02:13 AM

My all discrete prefilter class-D
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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.

kartino 2nd August 2006 02:14 AM

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This is the filmuation file in LTSpice

kartino 2nd August 2006 02:19 AM

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Gate driver... on-off

classd4sure 2nd August 2006 02:21 AM


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?

kartino 2nd August 2006 02:36 AM

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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..

kartino 2nd August 2006 03:03 AM

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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.

kartino 2nd August 2006 03:05 AM

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in PDF

kartino 2nd August 2006 05:22 AM

Does any guide to design zobel network for full range?

kartino 7th August 2006 04:15 AM

changing feedbak loop
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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.

kartino 7th August 2006 04:23 AM

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

Still no comment?

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