Nonlinear behavioral modeling and phase noise evaluation in phase locked loops

In this paper, a method is proposed for evaluating the phase noise spectrum of phase locked loops. Reliable loop simulations are based on a highly-accurate behavioral model for the voltage controlled oscillator. A verification is performed between the output spectrum of the VCO model and the transistor-level VCO spectrum as a function of the applied input voltage. This yields an accuracy better than 0.25 dBc/Hz. The phase noise spectrum of a phase locked loop is calculated. Simulation results are presented and compared with measurements.