The stability analysis of sampled-data systems with averaging samplers and time delays

Abstract

An exact analysis of the stability of a sampled-data feedback loop, involving an averaging sampler and continuous-time delays, is presented. An equivalent discrete-time model is derived and it is shown that the continuous-time behaviour at frequencies greater than the sample frequency can significantly affect the system stability, leading to counterintuitive analysis results. An optical fiber link synchronization application is studied with these methods. It is shown that the gain margin of the system increases with the addition of a small continuous-time delay and this effect is predicted only by the sampled-data approach.