On slide 4, what is the difference between the top graph in the Bode diagram and the bottom right graph? What are they graphing such that one is at 20dB and the other is at 0dB?

Tim Chung, 18 Nov 02

The top graph shows the open-loop gain, also called the loop-gain. This is equal to PC (P=plant, C=controller).

The bottom graph shows the closed-loop system, which is equivalent to: H = L/(1+L).