Stats

  • Locked Locked
  • Replies 1
  • Subscribers 125
  • Views 14264
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Stability and transient analysis do not match

unSkilled

Hi all,

I'm using virtuoso subversion IC6.1.7-64b.500.21 and spectre subversion 18.1.0.143.isr1.

I'm verifying stability in a nested multiloop LDO design, so I've introduced several probes to analyze each of the existing loops individually. The location of poles varies with the load current so two runs are made, one for no load and one for max load condition. One of the loops is showing me -40 degrees PM at high load condition but the transient analysis shows no oscillatory behavior. I know the iprobes from analogLib do not open the loop and should not be affecting the operating point of the circuit, but I'm having a hard time understanding what's the root cause of the different results and how to reconcile them.

How to make sure that stb results are reliable?

Attached you can see the simulation results. Let me know if anything else is needed (I show only a zoom in the transient response from zero to max current and viceversa)

  • unSkilled

    Apologies, I meant to place this thread under custom IC design, not custom IC SKILL

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.