transient simulation for feedback stability

[love_analog]

Say I have a feedback loop and I want to check stability of it through transients.

How do I figure out what transient amplitude (ie step input amplitude) and rise time do I put as stimulus.

do I put 5mV? 20mV ? 100mV
Is the rise time 5ps? 20ps? 100ps?

 

[dick_freebird]

I don't think it matters too much, the details - as long as you
drive it out of its small signal "comfort zone". That is, fully steer
the input diff pair so that it has railed the next stage (be sure
to do both directions).

Be sure you have good load models, such as ESR/ESL on output
caps of regulators, package and fixture inductances and so on.
These are often a way to make a niminally-stable part go un-.