MOS Power Amp -My Design

[Bob Scott]

Here's a simple MOSfet amp I designed. No bothersome bias adjustments!

Bob

[soekris]

.... Just bothersome handselecting parts as those mosfets have VGS(th) from 2V to 4V....

Soren

[nigelwright7557]

It will suffer badly from crossover distortion without a proper bias circuit.

[Bob Scott]

Originally Posted by soekris

.... Just bothersome handselecting parts as those mosfets have VGS(th) from 2V to 4V....

Soren

Ah, I see that now in the data sheet. Thanks for the tip. I see in IR's app notes, they do not recommend their MOSFETs use in analog amplifers due to the non-linearity. I say cure it with massive feedback. I think I'll add a unity gain op-amp just to linearize the output. Full speed ahead!

I will test a few Z44s with a 15V source and a 1K resistor. With the two in series and the gate connected to the drain, we'll see how much the gate voltages differ. Will the currents vary ~ 13-15mA? We'll see.

I don't think it will be much to worry about. I see MOSFETs wired in parallel all the time without regard to "turn-on voltage".

[ontoaba]

Is this class A?

[Bob Scott]

Originally Posted by onto aban

Is this class A?

AB