The circuit uses negative feedback from the comparator to adjust the counter until the DAC's output is close enough to the input signal.
From the en.wikipedia.org
One is a negative feedback release on behavior, and that part of the circuit is always active when overall brain activity is reduced, Dr. Schiff says.
From the sciencedaily.com
One problem for amplifier designers who use negative feedback is that some of the components of the circuit will introduce phase shift in the feedback path.