Estimating Phase Noise Using a Phase-Domain PLL Model

 Learn how to leverage a phase-domain PLL model in Simulink® to estimate phase noise. The linearization capability in Simulink Control Design™ is used to compute a coupled set of transfer functions in the form of a state-space object. The phase-domain model is treated as a multi-input single-output (MISO) system. The inputs model perturbations at various nodes in the PLL. The effect of noise disturbances on the reference input, charge pump, loop filter, and VCO is analyzed to see what effect such noises have on the PLL’s overall phase noise. The advantage of this approach is that no transfer functions need to be manually computed. Further, all system connections can be described quickly in graphical form making the model easy to create, modify, and share across teams.