Class A Amplifier from China

302

06:30:14

The 150k and 180R resistors control the current and output voltage with no input. The 2.2k is for gain.

published 8 years ago

hurz

8 years ago

I like this kind of amp and its simplicity were an PNP takes over the differential error amplifier for the outer feedback. Seen from input its a common emitter and seen from output to emitter its a common base input stage. I like that.

bryanthehacker

8 years ago

thebugger

8 years ago

Nice circuit, but it's not really a pure class A amp. Pure class A amps have a constant current source connected to the load and the active load transistor. Basically a class A amp can't be viewed as a push pull topology because both the pushing and pulling is handled by one active device. Your circuit is somewhat close to the death of zen topology, but with a class AB output stage.

hurz

8 years ago

With 590mV which is in this configuration the maximum input voltage, the current of the upper transistor is from 1.55A down to 0.43A and never close to zero. So for me it a good enough indication of a class A amplifier.

thebugger

8 years ago

In general a perfect current source at a few amps with a complex load is hard to accomplish, so a little deviation from ideal is ok, but I don't know, the current change big

hurz

8 years ago

Dont get what you saying buggzy, the load current is a little below the top BJT max current which is 1.55A. The load current is +-1.485Apeak. So what is your statement about " its not class A" now?

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