An alternative way of quantifying the stability of a negative-feedback system is via the gain margin gm, defi ned as gm 5 220 log uT( jf21808 )u, where f21808 represents the frequency at which ph T 5...

An alternative way of quantifying the stability of a negative-feedback system is via the gain margin gm, defi ned as gm 5 220 log uT( jf21808 )u, where f21808 represents the frequency at which ph T 5 21808. (As we know, for our system to be convincingly stable, we want uT( jf )u to have dropped well below 1 at f21808 ) (a) If an amplifi er with dc gain a0 5 105 and three pole frequencies f1 5 1 kHz, f2 5 1 MHz, and f3 5 10 MHz is to be operated in negative feedback, fi nd for m 5 608. What is the corresponding value of gm? (b) Find for gm 5 20 dB. What is the corresponding value of m?