Loop finder analysis for analog circuits

The loop finder (LF) analysis is a newly developed method for automatic loop identification and full chip stability analysis. It allows designers to find local and potentially problematic return loops in their analog circuits. Node impedance transfer functions in pole-residue format are utilized to generate second-order continuous-time systems that approximate the loops. This method was implemented in our in-house Spice-like simulator and has been very helpful identifying instability problems.