ldo stability analysis
Dear neter,
A phase margin of about 40 degrees is more than enough with the settling in a LDO with a switching load. It is mighty difficult to use a PMOS drop out transistor or a very low drop out and get a very high stability in a 60 degree phase margin. Also, ESR of the load capacitance can also determine the phase margin.
When you test the stability, you should do the loop gain test and not the open loop test in order to ascertain the phase margin.
I hope this note helps