(a) Consider a negative-feedback loop with dc gain T0 5 103 , a dominant pole at 1 kHz, and a pair of coincident poles at 250 kHz. Using trial and error, fi nd the crossover frequency fx and, hence,...

(a) Consider a negative-feedback loop with dc gain T0 5 103 , a dominant pole at 1 kHz, and a pair of coincident poles at 250 kHz. Using trial and error, fi nd the crossover frequency fx and, hence, the phase margin m, and verify that this loop is unstable. (b) One way of stabilizing it is to reduce T0 so that the ensuing downward shift of the magnitude plot will lower fx to a frequency region of less phase lag. Find the value to which T0 must be reduced for m 5 458. Hint: since the dominant-pole contribution to x is 2908, the coincident poles must contribute about 245y2 5 222.58 each. (c) As we know, another way is to reduce f1. To what value must f1 be reduced for m 5 458? (d) Repeat (b) and (c), but for m 5 608.