Effect of additional loop time delay on the performance of a nonlinear amplifier-based PLL with and without phase modulator

The paper shows, with the help of numerical simulation and hardware experiments, that the tracking response of a NLA-based second order PLL would be affected in the presence of additional loop time delay. The inclusion of a phase modulator in the system structure can reduce the adverse effects to some extent, but the design parameters should have to be properly chosen to pet a stable system.