1.   Observe, however, that negative and positive feedback respectively correspond to the loop gain being positive and negative in equation.

2.   The analysis of this section culminating in equations -- establishes that the magnitude of the effect of feedback always depends on the appropriate loop gain.

3.   Conversely, for oscillation to occur, the plot of the loop gain must enclose the point as the frequency changes.

4.   Recall that parasitic oscillation takes place if the magnitude of the loop gain is greater than or equal to unity at the frequency at which the phase shift becomes.