(Almost) half of any circuit´s operating points are unstable

This paper presents new results concerning the stability of operating points of dc circuits. The authors define two classes of unstable operating points and develop criteria for identifying the class to which a given operating point belongs. They also show, by employing results from degree theory, that if a circuit possesses n structurally stable operating points (n has been shown previously to be odd), then ½(n-1) of these operating points must be unstable and hence physically unobservable. A special case of this result proves that any bistable circuit must possess at least three operating points