Stability of state-delayed digital filters with overflow nonlinearities

Abstract

In this work, stability of digital filters in the presence of overflow nonlinearities and time-varying delay is investigated with/without external disturbance. Two new lemmas related to characterization of overflow nonlinearities are developed. The first lemma is established with better utilization of system information which includes overflow nonlinearities, previous and current states of the digital filter. The second lemma associated with overflow nonlinearities is developed with lesser constraints. Furthermore, by utilizing the established lemmas and a new Lyapunov functional, an asymptotic stability condition is presented for the digital filter with time-varying delay and overflow nonlinearities. The developed condition is shown to be more relaxed and computationally less demanding than the existing criteria. In addition to that, a sufficient condition is derived under which the digital filter with external disturbance, overflow nonlinearities, and time-varying delay has a prescribed noise attenuation level. To show the efficacy of the proposed approach, numerical examples are presented.