Design limitations and its effect in the performance of ZC1-DPLL

The paper studies the dynamics of a conventional positive going zero crossing type digital phase locked loop (ZC1-DPLL) taking non-ideal responses of the loop constituent blocks into account. The finite width of the sampling pulses and the finite propagation delay of the loop subsystems are properly modeled mathematically and the system dynamics is found to change because of their inf luence considered separately. However, when these two are taken simultaneously, the system dynamics can be made nearly equivalent to that of the ideal system. Through an extensive numerical simulation a set of optimum parameters to overcome design limitations have been obtained.