Calculation and avoidance of jump resonance in feedback amplifier circuits

A describing-function analysis, taking into account d.c. conditions, of a feedback structure containing a single asymmetrical nonlinearity representative of those occurring in solid-state and thermionic feedback amplifiers is used to calculate the closed-loop frequency response of such amplifiers. From this analysis, general conditions governing the shape of the open-loop frequency response for the avoidance of jump resonance are derived. It is shown that, when such shaping is not possible, a critical input amplitude exists below which jump resonance is absent, and a general expression for this amplitude is developed. Experimental work on a solid-state integrated-circuit amplifier having inherent jump resonance confirms the accuracy of the analysis and the conditions for jump avoidance.