What is the phase margin and gain margin for this circuit?

[Cocoleia]

Homework Statement

The Attempt at a Solution

I am having trouble visualizing this. So I know that the phase margin is how much phase lag it would take to make -180 phase at the 0 dB gain frequency. I am just having trouble placing this on the plot. It isn't a homework question I am preparing for an exam. I would think the answer is 45 degrees ?

 

[rude man]

Homework Statement

View attachment 224055

The Attempt at a Solution

I am having trouble visualizing this. So I know that the phase margin is how much phase lag it would take to make -180 phase at the 0 dB gain frequency. I am just having trouble placing this on the plot. It isn't a homework question I am preparing for an exam. I would think the answer is 45 degrees ?

Notice that at 180 deg phase shift the gain is still > 0dB!

 

[Cocoleia]

Notice that at 180 deg phase shift the gain is still > 0dB!

I'm not sure what I am supposed to looking at to figure this out then

 

[rude man]

If gain margin is negative, so must phase margin be, making what your answer?

 

[Cocoleia]

If gain margin is negative, so must phase margin be, making what your answer?

So then my answer would be none of the above so it can be negative ?

 

[rude man]

So then my answer would be none of the above so it can be negative ?

That's my vote.