A PLL is a difficult circuit to simulate using active and passive device models on a circuit simulator. Specially if it is a fast PLL. The signals are fast but the time constants of the filter are slow. The circuit simulator can have problems following both fast and slow signals. In addition it usually takes quite a few cycles of frequency to get a reasonable solution. (However if one is prepared to wait then the results can be very accurate at times.) A reasonable solution to  problems of simulation time and circuit simulator issues, is to use behavioral models which tend to very fast in simulation,  but not as accurate. A methodology that employs a mixture of MATLAB analysis, behavioral models and finally detailed circuit simulation is a practical one. Use MATLAB and behavioral models to get close to a solution and then fine tune using circuit simulation. Please vist the Signal Processing Group Inc.’s website for more technical information and ways to engage with us or simply ask questions or insert comments.