class AB APA crossover distortion

[armity]

I am designing class AB CMOS audio power amplifier,now I meet a problem.
There is a crossover distortion at OUTPUT.
MOS bias current is 1.2 mA,load RES=3 ohm
if load res >16 ohm,corossover distortion disapper.
I don't know how remove crossover distortion.
please help! thanks

 

[Verba]

may be you'll need to increase bias current, that will decrease the distortion

 

[armity]

thanks
Do you have anyway to remove the crossover distortion without increasing bias current.

 

[armity]

who would help me?

 

[Ave_Rapina]

Hello
You need a bias current that floats with the output charge that you connect
Example
Q6/ R8 / led +R9 Impose the bias courrent.
Regard that the bias courrent is connected to the charge.
When the charge is disconected there is no bias courrent that cam be important in portatil divise using bateries and you can fload a few mili amp in bias courrent when the charge is low.
Of course you nedd to project the bias corrent to create an 1.3 volt on D1 to polarize the output stage and elimitate de crossover courrent.
If one is not enought you can put 2 diodes or use an transistor to impose the bias corrent.
Any question please contact

Regards

 

[bigkitty]

you can try to increase the openloop bandwidth and phasemargin. The distortion at crossover maybe caused by insufficient phasemargin and bandwidth.