Failure of Barkhausen oscillation building up criterion: Further evidence

Abstract

It has been suggested in many textbooks that, given a closed-loop system, oscillation will commence and build up therein if the magnitude of loop gain is greater than unity at the frequency at which the angle of loop gain is zero degree. A novel ideal op-amp based counterexample to this suggestion is presented. The Letter serves to substantiate the findings in a recent Letter. A discussion relating to the finite gain of op-amp is included.