Analysis of phase noise of saturated ring oscillators

An in-depth review of the methods for phase noise analysis of saturated ring oscillators is presented. The assumption and limitation of the methods are investigated in detail. The framework of an efficient analysis method for the phase noise of saturated ring VCOs is presented. The method is based on the theory of periodically time-varying systems, in particular, the response of periodically time-varying systems to stochastic inputs. We show that both the up-conversion of low-frequency noise and down-conversion of broadband noise can be treated conveniently. The method provides an insight on how device noise is converted to the overall phase noise (timing jitter) of saturated oscillators.