stability fundamental--- help needed

[pbs681]

hi all,

need help to answer below questions:

1) for stability analysis, which gain that we plot: open loop gain or loop gain?

2) Is phase margin and UGF will change after we close the loop?

Thanks

 

[saro_k_82]

1. Loop gain (A*beta)., Only this reveals the PM, GM, UGB in all cases
2. PM and UGF will be same., as you have accounted for the closed-loop gain in the beta term