Positive feedback (or regenerative feedback) occurs in a feedback loop when the mathematical sign of the net gain around the feedback loop (sometimes called the loop gain) is positive. That is, positive feedback is in phase with the input, in the sense that it adds to make the input larger. Positive feedback is a process in which the effects of a small disturbance on a system can include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system that has negative gain around the loop has negative feedback.