Tighter limit cycle bounds for digital filters

A procedure for obtaining tighter bounds on zero-input limit cycles is presented. The proposed new bounds are applicable to digital filters of arbitrary order, described in state-space formulation and implemented with fixed-point arithmetic. For the most part, we obtain smaller bounds than those reported in the literature, using a computationally efficient algorithm that is easy to implement and has a comparatively short execution time. Simulation results show the validity of the proposed theory.