feedback loop compensation in error amplifier

[--BawA--]

Why there is a need of feedback loop compensation in error amplifier?
What's the purpose of using it? and how does it solve the purpose?

 

[chris.mourad]

Hi

This question is a nice one. I remember having entire courses at university on feedback loop compensation. I'll try to make it short though

Feedback loop compensation for an op-amp is a must have, in order to get a stable transient response.
Not having a feedback loop compensated leads to unstabilities, because you do not compensate for the huge gain of your amplifier.
The feedback loop compensation is in fact "slowing your amplifier", in order to have a phase difference between input and output lower than 180 degrees (This is where the concept of phase margin appears)
In other words, you don't want your opa's output to have a phase difference bigger than half a period with respect to the input, otherwise your amplifier never gets a stable response.