I am reading page 205 of “power supply cookbook” by Marty Brown, 2nd ed.

It says that there are three main parameters in SMPS stability…
1..Gain margin
2…Phase margin
3…Excess phase {“this is the point of closest approach of the phase characteristic to -360 degrees anytime the gain is greater than one (0dB) }

The book says that “excess phase” is the most important of these three parameters.
I cant believe this to be true?…I am sure I have read in Dr Ridley notes that if the phase crosses the -180 degree line whilst the gain is >1 it doesn’t matter, as long as the gain is say 10dB above zero?