Comment on "How to identify unstable DC operating points"

For original paper see M.M. Green and A.N. Willson, Jr., ibid., vol.39, pp.820-32 (1992). The modeling of capacitors and inductors in nonlinear circuits is discussed. In a previous paper by the author a theorem stated that all dependent current (voltage) sources must be terminated by a positive-valued capacitor (inductor). In this letter it is shown that this requirement can be relaxed so that only ports that contain controlling signals are required to be terminated by reactive elements.