aamar wrote on Jun 22nd, 2007, 2:01am: Hallo Frank,
I accept your answers no problems, the two poles could be on the left hand side, and even the zero, but I was replying to the original question where dandelion said
"At the point A, the phase obviously reaches -180'C while the gain is larger than one, what's the impact to the performance at thsi freq?"
and I think he means the step response nothing else or at least what will happen if you applied a signal with exactly this frequency to the system.
Any how it is good to mention that the problem can have a different face if we look to it in another domain.
Thanks and best regards,
aamar
yes, just as aamar said, what I mean is i wonder if the step response or other injection will induce ring even they will not oscillate eventurally.
Here lead to my another question. In many design spec, it will always give the phase margin spec, e.g., it is needed to be larger than ~60 degrees. I want to know, here, if the phase margin >60'C is needed to guarantee the circuit will not oscillate by itsself eventuarlly?. Or 60'C is needed to guarantee good setting behavior, i.e., 60'C can have good step response which has no rings?
I found the word "stabilty" made many people puzzle.
So, would you pls. give me some commnets?
Thanks