Kunthrandum - OpAmp biased MOSFET amp

[ronybc]

Hello again...

please share your valuable opinions and advice about this amp.

http://www.ronybc.8k.com/kunthrandum.htm

 

[mikeks]

Interesting design....

 

[ronybc]

There is minor changes to the page

I didn't construct this amp yet. Please check my design and let me know whether there is anything to be added, avoided or altered.

Please share your knowledge and experience over this circuit.

Thank you...

 

[darkfenriz]

check it for cross-conduction at 10kHz

 

[ronybc]

The simulated currents at both mosfet sources are shown in the figure. Using 1Vp-p, 10kHz at input, I found no problems. Please give me more details about the cross-conduction problem. I'm using LTspice here. What was the voltage across bias capacitor..?

Sometimes I get starting problems which could be eliminated by starting the 'quiescent current adj.' voltage from zero.

 

[darkfenriz]

Very nice then. I thought a non-inverting opamp driving a lower BJT may have some phase shift and cause output stage mosfets to switch in wrong moments. But it looks OK.
regards

 

[ronybc]

Version 1.2

Heyyy...

SORRY... I saw high cross conduction when I simulated the circuit with High gate capacitance mosfets, feed with a High-High signal (30Vp-p@200kHz). The circuit will smoke.

I've modified the circuit and posted it on my website. Now it is OK in such conditions. Using current mirrors instead R15 & R16 in the previous circuit works also.

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