Abstract
In this paper we deal with the sampled-data feedback systems with a class of nonlinearities modeled as the parallel connection of a memoryless time-invariant nonlinearity and a dynamical time-varying nonlinearity. We derive a stability criterion for such systems, which includes as special cases the stability criteria of Popov type and circle-criterion type, and which corresponds to the shifted Popov criterion in the continuous-time case. We also show that checking the stability condition of this criterion reduces to a convex problem in the frequency domain.
