PA new class A

134

02:16:33

The output power transistors keep turn-on status.

published 5 years ago

fatcat2

5 years ago

Wow, great design. Those resistors in series with the 4mA tail current sources reduce the open-loop gain and thus the feedback factor. Elimination of those resistors will prove to improve the circuit parameters. One question though; is a collector resistor needed at the collector of the Vbe multiplier stage? Normally, a low-value extra collector resistor is included in the Vbe multiplier so that the final voltage across it changes less according to the small tail current variations; a peaking mechanism with the slope minimum near the peak. Is such a resistor needed here?

benmo

5 years ago

Hi fatcat2, Do you mean the 100 and the 4.7k ohm resistors?

fatcat2

5 years ago

I only mean the 4.7k ohm resistors as the other 2 are for reducing the overall distortion.

benmo

5 years ago

Actually, the 4mA current source, I use a transistor 2SK30A to do. the Vcc to Vss almost 120VDC, using the 4.7k resistor for drop down the voltage protect the differential transistor and the current source transistors. that maybe not a good design. HaHaa..

fatcat2

5 years ago

Yeah

fatcat2

5 years ago

It decreases the open-loop gain and also increases the chance of clipping.

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