Nonlinear Phase-Domain Macromodeling of Injection-Locked Frequency Dividers

This paper describes an original nonlinear phase-domain macromodel of Injection-Locked Frequency Dividers which are driven by a nonlinear input device that produces heavy harmonic distortion. These non-harmonic frequency dividers can provide wide lock ranges, however their analysis is complicated by the strong nonlinear behavior for which the hypothesis of weak injection does not apply. The proposed approach consists in adopting a nonlinear model for the input section of the divider and in combining it with a Perturbation-Projection-Vector-based macromodel for the linear-time-varying section of the oscillator. The proposed macromodel is employed to predict the synchronization regions of an ILFD driven by several types of injected waveforms. In addition, closed-form expressions for the output phase-noise spectrum are also provided.