why the BW can't design to 20KHz in classd audio amplifer.

[rocky_pol]

I am designing class D audio amplifer with 3W,I find it hard to design BW to 20KHz,It need better THD and PSRR,so the Au of system is large, that result in smaller BW that can't design to 20K,who can help me about it? thanks!!!

 

[dick_freebird]

What is holding you back? Switching frequency and the loop BW
needed to filter that out?

 

[rocky_pol]

Re: why the BW can't design to 20KHz in classd audio amplife

What is holding you back? Switching frequency and the loop BW
needed to filter that out?

first of all, Thank you for quick responding.
The frequency is 250KHz,Beause range of audio is 20H~20KH,so I feel that the loop BW should be designed to 20k above, right?

 

[watersky]

I think the loop BW should not be 20KHz, what is the effection of loop? perhaps you should search some patents about pole and zero of audio loop. It is related with loop configuration, such as single loop or double loop.

 

[rocky_pol]

Re: why the BW can't design to 20KHz in classd audio amplife

Thank you for replying above, I don't always clear ,who can interpret it for me, thanks!

 

[mengcy]

do you mean the bw of the integrator?
I think if you design the bw to 20k, in the audio frequency range you can't obtain a uniform phase shift.
however,if you want to get a better THD,you should enlarge the bw.