The historic account of the Phase-Locked Loops can be traced back from the idea of designing an electromechanical system with the objective of controlling the oscillation of the pendulum of the bell Great George. The method is to contrast the phase of pendulum and the incoming telegraph signal phase using the electromechanical system. That generates the correction signal varying the pendulum oscillation. The idea was conceived as well as implemented by David Robertson, Professor of Electrical Engineering at the University of Bristol. The term Phase-Locked Loop was coined to this technique by later Researchers in 1932. Professor David Robertson is credited to the Phase-Locked Loop for pioneering the technique. In general setting, the Phase-Locked Loops are for synchronization purposes. The phase locked loops perspective hinges on the analysis, functions and applications.