/diy/ - Do It Yourself

I don't understand how to implement negative feedback, at least not outside of op-amp circuits where it's really straightforward. So what are the different ways to implement negative feedback in BJT and JFET amplifiers and other circuits with control loops and how exactly is degeneration negative feedback (you don't appear to be feeding back signal from the output to the input)?

I made a basic common emitter amp and tried to apply some current feedback by taking some current from the output and feeding it back to the emitter node and likewise taking some from the output and feeding it to the base. I'm not sure either of these are negative feedback or not though the latter also provides bias.

Also when you use an active current source instead of a resistor for a fixed bias design does that help eliminate the disadvantages of that topology (variable collector current as temp and power supply voltage varies, variation in Vbe and beta, and susceptibility to thermal runaway?)

Sorry for like the 900 different questions.