I. Introduction
Nonlinear microwave circuits under periodic excitation can exhibit a variety of nonstandard behaviors, including [1]–[3] multiple steady states (typically with different stability properties), hysteresis and jump phenomena with respect to variation of a parameter (such as bias voltage) [4], [5], subharmonic solutions [6], parametric oscillations, quasi-periodic solutions [7], and finally chaotic solutions [8]. Practicing RF designers have a variety of colorful jargon names for such behaviors; however, the modern language of dynamical systems theory [8]–[11] allows for a much more precise description of such phenomena.