AbstractThe systems to be considered consist of linear and nonlinear elements and are driven bya prioriknown periodic signals (carriers). The present theory deals with small perturbations from the periodic steady state. Use has been made of the ‘amplitude‐phase’ representation of the perturbations. The operator (jω0+ λ) is used, in which jω0indicates the time differentiation of the carrier components and the operator λ ( = d/dt) affects the perturbation only. The perturbations will be related by a ‘sensitivity’ matrixH. In order to illustrate the applicability of this theory, the performance of the dynamic limiter of Zaalberg van Zelst wi