Difference between Class a and a/b


Hi,

I have been reading alot about class a and class a/b biased amps, but I am not really clear on what the difference is. I understand that it has to do with circuit providing power through the entire cycle. But I was hoping that someone may be able to explain it in simpler terms.

Any help is greatly appreciated.

Thanks

Craig
species253

Showing 1 response by nhtran

zoya,

your explaination is incorrect. Your description of class A is actually a single ended design(i.e. one output device handling the entire signal). class A can also use two output devices, one handling each phase. however both devices stay powered up at all times, even when not used to drive the speakers (i.e. each device stays powered up for the entire 360 degrees).

your description of class a/b is actually a description of class b (i.e. the out device powers down at zero crossing or at 180 degrees). In class a/b each device stays powered up beyond zero crossing, but not for the entire signal (say 200 to 300 degrees). when you hear manufacturers claim a "high class a bias", they are talking about how far past zero crossing the output device stays on.